5815 lines
157 KiB
C
5815 lines
157 KiB
C
/*
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* Generic process-grouping system.
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*
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* Based originally on the cpuset system, extracted by Paul Menage
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* Copyright (C) 2006 Google, Inc
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*
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* Notifications support
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* Copyright (C) 2009 Nokia Corporation
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* Author: Kirill A. Shutemov
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*
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* Copyright notices from the original cpuset code:
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* --------------------------------------------------
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* Copyright (C) 2003 BULL SA.
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* Copyright (C) 2004-2006 Silicon Graphics, Inc.
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*
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* Portions derived from Patrick Mochel's sysfs code.
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* sysfs is Copyright (c) 2001-3 Patrick Mochel
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*
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* 2003-10-10 Written by Simon Derr.
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* 2003-10-22 Updates by Stephen Hemminger.
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* 2004 May-July Rework by Paul Jackson.
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* ---------------------------------------------------
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file COPYING in the main directory of the Linux
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* distribution for more details.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/cgroup.h>
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#include <linux/cred.h>
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#include <linux/ctype.h>
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#include <linux/errno.h>
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#include <linux/init_task.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/magic.h>
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#include <linux/mm.h>
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#include <linux/mutex.h>
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#include <linux/mount.h>
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#include <linux/pagemap.h>
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#include <linux/proc_fs.h>
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#include <linux/rcupdate.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/rwsem.h>
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#include <linux/percpu-rwsem.h>
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#include <linux/string.h>
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#include <linux/sort.h>
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#include <linux/kmod.h>
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#include <linux/delayacct.h>
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#include <linux/cgroupstats.h>
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#include <linux/hashtable.h>
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#include <linux/pid_namespace.h>
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#include <linux/idr.h>
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#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
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#include <linux/kthread.h>
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#include <linux/delay.h>
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#include <linux/atomic.h>
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/*
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* pidlists linger the following amount before being destroyed. The goal
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* is avoiding frequent destruction in the middle of consecutive read calls
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* Expiring in the middle is a performance problem not a correctness one.
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* 1 sec should be enough.
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*/
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#define CGROUP_PIDLIST_DESTROY_DELAY HZ
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#define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
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MAX_CFTYPE_NAME + 2)
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/*
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* cgroup_mutex is the master lock. Any modification to cgroup or its
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* hierarchy must be performed while holding it.
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*
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* css_set_rwsem protects task->cgroups pointer, the list of css_set
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* objects, and the chain of tasks off each css_set.
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*
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* These locks are exported if CONFIG_PROVE_RCU so that accessors in
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* cgroup.h can use them for lockdep annotations.
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*/
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#ifdef CONFIG_PROVE_RCU
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DEFINE_MUTEX(cgroup_mutex);
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DECLARE_RWSEM(css_set_rwsem);
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EXPORT_SYMBOL_GPL(cgroup_mutex);
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EXPORT_SYMBOL_GPL(css_set_rwsem);
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#else
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static DEFINE_MUTEX(cgroup_mutex);
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static DECLARE_RWSEM(css_set_rwsem);
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#endif
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/*
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* Protects cgroup_idr and css_idr so that IDs can be released without
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* grabbing cgroup_mutex.
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*/
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static DEFINE_SPINLOCK(cgroup_idr_lock);
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/*
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* Protects cgroup_subsys->release_agent_path. Modifying it also requires
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* cgroup_mutex. Reading requires either cgroup_mutex or this spinlock.
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*/
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static DEFINE_SPINLOCK(release_agent_path_lock);
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struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
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#define cgroup_assert_mutex_or_rcu_locked() \
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RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
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!lockdep_is_held(&cgroup_mutex), \
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"cgroup_mutex or RCU read lock required");
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/*
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* cgroup destruction makes heavy use of work items and there can be a lot
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* of concurrent destructions. Use a separate workqueue so that cgroup
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* destruction work items don't end up filling up max_active of system_wq
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* which may lead to deadlock.
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*/
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static struct workqueue_struct *cgroup_destroy_wq;
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/*
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* pidlist destructions need to be flushed on cgroup destruction. Use a
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* separate workqueue as flush domain.
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*/
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static struct workqueue_struct *cgroup_pidlist_destroy_wq;
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/* generate an array of cgroup subsystem pointers */
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#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
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static struct cgroup_subsys *cgroup_subsys[] = {
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#include <linux/cgroup_subsys.h>
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};
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#undef SUBSYS
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/* array of cgroup subsystem names */
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#define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
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static const char *cgroup_subsys_name[] = {
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#include <linux/cgroup_subsys.h>
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};
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#undef SUBSYS
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/* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */
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#define SUBSYS(_x) \
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DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \
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DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \
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EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \
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EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key);
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#include <linux/cgroup_subsys.h>
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#undef SUBSYS
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#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key,
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static struct static_key_true *cgroup_subsys_enabled_key[] = {
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#include <linux/cgroup_subsys.h>
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};
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#undef SUBSYS
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#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key,
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static struct static_key_true *cgroup_subsys_on_dfl_key[] = {
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#include <linux/cgroup_subsys.h>
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};
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#undef SUBSYS
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/*
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* The default hierarchy, reserved for the subsystems that are otherwise
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* unattached - it never has more than a single cgroup, and all tasks are
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* part of that cgroup.
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*/
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struct cgroup_root cgrp_dfl_root;
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EXPORT_SYMBOL_GPL(cgrp_dfl_root);
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/*
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* The default hierarchy always exists but is hidden until mounted for the
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* first time. This is for backward compatibility.
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*/
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static bool cgrp_dfl_root_visible;
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/*
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* Set by the boot param of the same name and makes subsystems with NULL
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* ->dfl_files to use ->legacy_files on the default hierarchy.
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*/
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static bool cgroup_legacy_files_on_dfl;
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/* some controllers are not supported in the default hierarchy */
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static unsigned long cgrp_dfl_root_inhibit_ss_mask;
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/* The list of hierarchy roots */
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static LIST_HEAD(cgroup_roots);
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static int cgroup_root_count;
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/* hierarchy ID allocation and mapping, protected by cgroup_mutex */
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static DEFINE_IDR(cgroup_hierarchy_idr);
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/*
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* Assign a monotonically increasing serial number to csses. It guarantees
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* cgroups with bigger numbers are newer than those with smaller numbers.
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* Also, as csses are always appended to the parent's ->children list, it
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* guarantees that sibling csses are always sorted in the ascending serial
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* number order on the list. Protected by cgroup_mutex.
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*/
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static u64 css_serial_nr_next = 1;
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/*
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* These bitmask flags indicate whether tasks in the fork and exit paths have
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* fork/exit handlers to call. This avoids us having to do extra work in the
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* fork/exit path to check which subsystems have fork/exit callbacks.
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*/
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static unsigned long have_fork_callback __read_mostly;
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static unsigned long have_exit_callback __read_mostly;
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/* Ditto for the can_fork callback. */
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static unsigned long have_canfork_callback __read_mostly;
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static struct cftype cgroup_dfl_base_files[];
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static struct cftype cgroup_legacy_base_files[];
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static int rebind_subsystems(struct cgroup_root *dst_root,
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unsigned long ss_mask);
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static int cgroup_destroy_locked(struct cgroup *cgrp);
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static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,
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bool visible);
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static void css_release(struct percpu_ref *ref);
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static void kill_css(struct cgroup_subsys_state *css);
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static int cgroup_addrm_files(struct cgroup_subsys_state *css,
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struct cgroup *cgrp, struct cftype cfts[],
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bool is_add);
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/**
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* cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID
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* @ssid: subsys ID of interest
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*
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* cgroup_subsys_enabled() can only be used with literal subsys names which
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* is fine for individual subsystems but unsuitable for cgroup core. This
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* is slower static_key_enabled() based test indexed by @ssid.
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*/
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static bool cgroup_ssid_enabled(int ssid)
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{
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return static_key_enabled(cgroup_subsys_enabled_key[ssid]);
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}
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/**
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* cgroup_on_dfl - test whether a cgroup is on the default hierarchy
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* @cgrp: the cgroup of interest
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*
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* The default hierarchy is the v2 interface of cgroup and this function
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* can be used to test whether a cgroup is on the default hierarchy for
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* cases where a subsystem should behave differnetly depending on the
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* interface version.
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*
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* The set of behaviors which change on the default hierarchy are still
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* being determined and the mount option is prefixed with __DEVEL__.
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*
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* List of changed behaviors:
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*
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* - Mount options "noprefix", "xattr", "clone_children", "release_agent"
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* and "name" are disallowed.
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*
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* - When mounting an existing superblock, mount options should match.
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*
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* - Remount is disallowed.
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*
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* - rename(2) is disallowed.
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*
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* - "tasks" is removed. Everything should be at process granularity. Use
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* "cgroup.procs" instead.
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*
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* - "cgroup.procs" is not sorted. pids will be unique unless they got
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* recycled inbetween reads.
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*
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* - "release_agent" and "notify_on_release" are removed. Replacement
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* notification mechanism will be implemented.
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*
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* - "cgroup.clone_children" is removed.
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*
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* - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
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* and its descendants contain no task; otherwise, 1. The file also
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* generates kernfs notification which can be monitored through poll and
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* [di]notify when the value of the file changes.
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*
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* - cpuset: tasks will be kept in empty cpusets when hotplug happens and
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* take masks of ancestors with non-empty cpus/mems, instead of being
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* moved to an ancestor.
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*
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* - cpuset: a task can be moved into an empty cpuset, and again it takes
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* masks of ancestors.
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*
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* - memcg: use_hierarchy is on by default and the cgroup file for the flag
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* is not created.
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*
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* - blkcg: blk-throttle becomes properly hierarchical.
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*
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* - debug: disallowed on the default hierarchy.
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*/
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static bool cgroup_on_dfl(const struct cgroup *cgrp)
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{
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return cgrp->root == &cgrp_dfl_root;
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}
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/* IDR wrappers which synchronize using cgroup_idr_lock */
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static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end,
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gfp_t gfp_mask)
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{
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int ret;
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idr_preload(gfp_mask);
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spin_lock_bh(&cgroup_idr_lock);
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ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_WAIT);
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spin_unlock_bh(&cgroup_idr_lock);
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idr_preload_end();
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return ret;
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}
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static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id)
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{
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void *ret;
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spin_lock_bh(&cgroup_idr_lock);
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ret = idr_replace(idr, ptr, id);
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spin_unlock_bh(&cgroup_idr_lock);
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return ret;
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}
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static void cgroup_idr_remove(struct idr *idr, int id)
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{
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spin_lock_bh(&cgroup_idr_lock);
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idr_remove(idr, id);
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spin_unlock_bh(&cgroup_idr_lock);
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}
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static struct cgroup *cgroup_parent(struct cgroup *cgrp)
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{
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struct cgroup_subsys_state *parent_css = cgrp->self.parent;
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if (parent_css)
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return container_of(parent_css, struct cgroup, self);
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return NULL;
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}
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/**
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* cgroup_css - obtain a cgroup's css for the specified subsystem
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* @cgrp: the cgroup of interest
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* @ss: the subsystem of interest (%NULL returns @cgrp->self)
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*
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* Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
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* function must be called either under cgroup_mutex or rcu_read_lock() and
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* the caller is responsible for pinning the returned css if it wants to
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* keep accessing it outside the said locks. This function may return
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* %NULL if @cgrp doesn't have @subsys_id enabled.
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*/
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static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
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struct cgroup_subsys *ss)
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{
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if (ss)
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return rcu_dereference_check(cgrp->subsys[ss->id],
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lockdep_is_held(&cgroup_mutex));
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else
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return &cgrp->self;
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}
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/**
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* cgroup_e_css - obtain a cgroup's effective css for the specified subsystem
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* @cgrp: the cgroup of interest
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* @ss: the subsystem of interest (%NULL returns @cgrp->self)
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*
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* Similar to cgroup_css() but returns the effective css, which is defined
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* as the matching css of the nearest ancestor including self which has @ss
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* enabled. If @ss is associated with the hierarchy @cgrp is on, this
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* function is guaranteed to return non-NULL css.
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*/
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static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp,
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struct cgroup_subsys *ss)
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{
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lockdep_assert_held(&cgroup_mutex);
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if (!ss)
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return &cgrp->self;
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if (!(cgrp->root->subsys_mask & (1 << ss->id)))
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return NULL;
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/*
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* This function is used while updating css associations and thus
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* can't test the csses directly. Use ->child_subsys_mask.
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*/
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while (cgroup_parent(cgrp) &&
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!(cgroup_parent(cgrp)->child_subsys_mask & (1 << ss->id)))
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cgrp = cgroup_parent(cgrp);
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return cgroup_css(cgrp, ss);
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}
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/**
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* cgroup_get_e_css - get a cgroup's effective css for the specified subsystem
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* @cgrp: the cgroup of interest
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* @ss: the subsystem of interest
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*
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* Find and get the effective css of @cgrp for @ss. The effective css is
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* defined as the matching css of the nearest ancestor including self which
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* has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
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* the root css is returned, so this function always returns a valid css.
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* The returned css must be put using css_put().
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*/
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struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
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struct cgroup_subsys *ss)
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{
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struct cgroup_subsys_state *css;
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rcu_read_lock();
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do {
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css = cgroup_css(cgrp, ss);
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if (css && css_tryget_online(css))
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goto out_unlock;
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cgrp = cgroup_parent(cgrp);
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} while (cgrp);
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css = init_css_set.subsys[ss->id];
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css_get(css);
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out_unlock:
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rcu_read_unlock();
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return css;
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}
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/* convenient tests for these bits */
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static inline bool cgroup_is_dead(const struct cgroup *cgrp)
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{
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return !(cgrp->self.flags & CSS_ONLINE);
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}
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struct cgroup_subsys_state *of_css(struct kernfs_open_file *of)
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{
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struct cgroup *cgrp = of->kn->parent->priv;
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struct cftype *cft = of_cft(of);
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/*
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* This is open and unprotected implementation of cgroup_css().
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* seq_css() is only called from a kernfs file operation which has
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* an active reference on the file. Because all the subsystem
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* files are drained before a css is disassociated with a cgroup,
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* the matching css from the cgroup's subsys table is guaranteed to
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* be and stay valid until the enclosing operation is complete.
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*/
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if (cft->ss)
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return rcu_dereference_raw(cgrp->subsys[cft->ss->id]);
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else
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return &cgrp->self;
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}
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EXPORT_SYMBOL_GPL(of_css);
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|
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/**
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* cgroup_is_descendant - test ancestry
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* @cgrp: the cgroup to be tested
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* @ancestor: possible ancestor of @cgrp
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*
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* Test whether @cgrp is a descendant of @ancestor. It also returns %true
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* if @cgrp == @ancestor. This function is safe to call as long as @cgrp
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* and @ancestor are accessible.
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*/
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bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor)
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{
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while (cgrp) {
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if (cgrp == ancestor)
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return true;
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cgrp = cgroup_parent(cgrp);
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}
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return false;
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}
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static int notify_on_release(const struct cgroup *cgrp)
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{
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return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
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}
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|
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/**
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* for_each_css - iterate all css's of a cgroup
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* @css: the iteration cursor
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* @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
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* @cgrp: the target cgroup to iterate css's of
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*
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* Should be called under cgroup_[tree_]mutex.
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*/
|
|
#define for_each_css(css, ssid, cgrp) \
|
|
for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
|
|
if (!((css) = rcu_dereference_check( \
|
|
(cgrp)->subsys[(ssid)], \
|
|
lockdep_is_held(&cgroup_mutex)))) { } \
|
|
else
|
|
|
|
/**
|
|
* for_each_e_css - iterate all effective css's of a cgroup
|
|
* @css: the iteration cursor
|
|
* @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
|
|
* @cgrp: the target cgroup to iterate css's of
|
|
*
|
|
* Should be called under cgroup_[tree_]mutex.
|
|
*/
|
|
#define for_each_e_css(css, ssid, cgrp) \
|
|
for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
|
|
if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \
|
|
; \
|
|
else
|
|
|
|
/**
|
|
* for_each_subsys - iterate all enabled cgroup subsystems
|
|
* @ss: the iteration cursor
|
|
* @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
|
|
*/
|
|
#define for_each_subsys(ss, ssid) \
|
|
for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \
|
|
(((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
|
|
|
|
/**
|
|
* for_each_subsys_which - filter for_each_subsys with a bitmask
|
|
* @ss: the iteration cursor
|
|
* @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
|
|
* @ss_maskp: a pointer to the bitmask
|
|
*
|
|
* The block will only run for cases where the ssid-th bit (1 << ssid) of
|
|
* mask is set to 1.
|
|
*/
|
|
#define for_each_subsys_which(ss, ssid, ss_maskp) \
|
|
if (!CGROUP_SUBSYS_COUNT) /* to avoid spurious gcc warning */ \
|
|
(ssid) = 0; \
|
|
else \
|
|
for_each_set_bit(ssid, ss_maskp, CGROUP_SUBSYS_COUNT) \
|
|
if (((ss) = cgroup_subsys[ssid]) && false) \
|
|
break; \
|
|
else
|
|
|
|
/* iterate across the hierarchies */
|
|
#define for_each_root(root) \
|
|
list_for_each_entry((root), &cgroup_roots, root_list)
|
|
|
|
/* iterate over child cgrps, lock should be held throughout iteration */
|
|
#define cgroup_for_each_live_child(child, cgrp) \
|
|
list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \
|
|
if (({ lockdep_assert_held(&cgroup_mutex); \
|
|
cgroup_is_dead(child); })) \
|
|
; \
|
|
else
|
|
|
|
static void cgroup_release_agent(struct work_struct *work);
|
|
static void check_for_release(struct cgroup *cgrp);
|
|
|
|
/*
|
|
* A cgroup can be associated with multiple css_sets as different tasks may
|
|
* belong to different cgroups on different hierarchies. In the other
|
|
* direction, a css_set is naturally associated with multiple cgroups.
|
|
* This M:N relationship is represented by the following link structure
|
|
* which exists for each association and allows traversing the associations
|
|
* from both sides.
|
|
*/
|
|
struct cgrp_cset_link {
|
|
/* the cgroup and css_set this link associates */
|
|
struct cgroup *cgrp;
|
|
struct css_set *cset;
|
|
|
|
/* list of cgrp_cset_links anchored at cgrp->cset_links */
|
|
struct list_head cset_link;
|
|
|
|
/* list of cgrp_cset_links anchored at css_set->cgrp_links */
|
|
struct list_head cgrp_link;
|
|
};
|
|
|
|
/*
|
|
* The default css_set - used by init and its children prior to any
|
|
* hierarchies being mounted. It contains a pointer to the root state
|
|
* for each subsystem. Also used to anchor the list of css_sets. Not
|
|
* reference-counted, to improve performance when child cgroups
|
|
* haven't been created.
|
|
*/
|
|
struct css_set init_css_set = {
|
|
.refcount = ATOMIC_INIT(1),
|
|
.cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links),
|
|
.tasks = LIST_HEAD_INIT(init_css_set.tasks),
|
|
.mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks),
|
|
.mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node),
|
|
.mg_node = LIST_HEAD_INIT(init_css_set.mg_node),
|
|
};
|
|
|
|
static int css_set_count = 1; /* 1 for init_css_set */
|
|
|
|
/**
|
|
* cgroup_update_populated - updated populated count of a cgroup
|
|
* @cgrp: the target cgroup
|
|
* @populated: inc or dec populated count
|
|
*
|
|
* @cgrp is either getting the first task (css_set) or losing the last.
|
|
* Update @cgrp->populated_cnt accordingly. The count is propagated
|
|
* towards root so that a given cgroup's populated_cnt is zero iff the
|
|
* cgroup and all its descendants are empty.
|
|
*
|
|
* @cgrp's interface file "cgroup.populated" is zero if
|
|
* @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt
|
|
* changes from or to zero, userland is notified that the content of the
|
|
* interface file has changed. This can be used to detect when @cgrp and
|
|
* its descendants become populated or empty.
|
|
*/
|
|
static void cgroup_update_populated(struct cgroup *cgrp, bool populated)
|
|
{
|
|
lockdep_assert_held(&css_set_rwsem);
|
|
|
|
do {
|
|
bool trigger;
|
|
|
|
if (populated)
|
|
trigger = !cgrp->populated_cnt++;
|
|
else
|
|
trigger = !--cgrp->populated_cnt;
|
|
|
|
if (!trigger)
|
|
break;
|
|
|
|
cgroup_file_notify(&cgrp->events_file);
|
|
|
|
cgrp = cgroup_parent(cgrp);
|
|
} while (cgrp);
|
|
}
|
|
|
|
/*
|
|
* hash table for cgroup groups. This improves the performance to find
|
|
* an existing css_set. This hash doesn't (currently) take into
|
|
* account cgroups in empty hierarchies.
|
|
*/
|
|
#define CSS_SET_HASH_BITS 7
|
|
static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS);
|
|
|
|
static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
|
|
{
|
|
unsigned long key = 0UL;
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
for_each_subsys(ss, i)
|
|
key += (unsigned long)css[i];
|
|
key = (key >> 16) ^ key;
|
|
|
|
return key;
|
|
}
|
|
|
|
static void put_css_set_locked(struct css_set *cset)
|
|
{
|
|
struct cgrp_cset_link *link, *tmp_link;
|
|
struct cgroup_subsys *ss;
|
|
int ssid;
|
|
|
|
lockdep_assert_held(&css_set_rwsem);
|
|
|
|
if (!atomic_dec_and_test(&cset->refcount))
|
|
return;
|
|
|
|
/* This css_set is dead. unlink it and release cgroup refcounts */
|
|
for_each_subsys(ss, ssid)
|
|
list_del(&cset->e_cset_node[ssid]);
|
|
hash_del(&cset->hlist);
|
|
css_set_count--;
|
|
|
|
list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) {
|
|
struct cgroup *cgrp = link->cgrp;
|
|
|
|
list_del(&link->cset_link);
|
|
list_del(&link->cgrp_link);
|
|
|
|
/* @cgrp can't go away while we're holding css_set_rwsem */
|
|
if (list_empty(&cgrp->cset_links)) {
|
|
cgroup_update_populated(cgrp, false);
|
|
check_for_release(cgrp);
|
|
}
|
|
|
|
kfree(link);
|
|
}
|
|
|
|
kfree_rcu(cset, rcu_head);
|
|
}
|
|
|
|
static void put_css_set(struct css_set *cset)
|
|
{
|
|
/*
|
|
* Ensure that the refcount doesn't hit zero while any readers
|
|
* can see it. Similar to atomic_dec_and_lock(), but for an
|
|
* rwlock
|
|
*/
|
|
if (atomic_add_unless(&cset->refcount, -1, 1))
|
|
return;
|
|
|
|
down_write(&css_set_rwsem);
|
|
put_css_set_locked(cset);
|
|
up_write(&css_set_rwsem);
|
|
}
|
|
|
|
/*
|
|
* refcounted get/put for css_set objects
|
|
*/
|
|
static inline void get_css_set(struct css_set *cset)
|
|
{
|
|
atomic_inc(&cset->refcount);
|
|
}
|
|
|
|
/**
|
|
* compare_css_sets - helper function for find_existing_css_set().
|
|
* @cset: candidate css_set being tested
|
|
* @old_cset: existing css_set for a task
|
|
* @new_cgrp: cgroup that's being entered by the task
|
|
* @template: desired set of css pointers in css_set (pre-calculated)
|
|
*
|
|
* Returns true if "cset" matches "old_cset" except for the hierarchy
|
|
* which "new_cgrp" belongs to, for which it should match "new_cgrp".
|
|
*/
|
|
static bool compare_css_sets(struct css_set *cset,
|
|
struct css_set *old_cset,
|
|
struct cgroup *new_cgrp,
|
|
struct cgroup_subsys_state *template[])
|
|
{
|
|
struct list_head *l1, *l2;
|
|
|
|
/*
|
|
* On the default hierarchy, there can be csets which are
|
|
* associated with the same set of cgroups but different csses.
|
|
* Let's first ensure that csses match.
|
|
*/
|
|
if (memcmp(template, cset->subsys, sizeof(cset->subsys)))
|
|
return false;
|
|
|
|
/*
|
|
* Compare cgroup pointers in order to distinguish between
|
|
* different cgroups in hierarchies. As different cgroups may
|
|
* share the same effective css, this comparison is always
|
|
* necessary.
|
|
*/
|
|
l1 = &cset->cgrp_links;
|
|
l2 = &old_cset->cgrp_links;
|
|
while (1) {
|
|
struct cgrp_cset_link *link1, *link2;
|
|
struct cgroup *cgrp1, *cgrp2;
|
|
|
|
l1 = l1->next;
|
|
l2 = l2->next;
|
|
/* See if we reached the end - both lists are equal length. */
|
|
if (l1 == &cset->cgrp_links) {
|
|
BUG_ON(l2 != &old_cset->cgrp_links);
|
|
break;
|
|
} else {
|
|
BUG_ON(l2 == &old_cset->cgrp_links);
|
|
}
|
|
/* Locate the cgroups associated with these links. */
|
|
link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link);
|
|
link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link);
|
|
cgrp1 = link1->cgrp;
|
|
cgrp2 = link2->cgrp;
|
|
/* Hierarchies should be linked in the same order. */
|
|
BUG_ON(cgrp1->root != cgrp2->root);
|
|
|
|
/*
|
|
* If this hierarchy is the hierarchy of the cgroup
|
|
* that's changing, then we need to check that this
|
|
* css_set points to the new cgroup; if it's any other
|
|
* hierarchy, then this css_set should point to the
|
|
* same cgroup as the old css_set.
|
|
*/
|
|
if (cgrp1->root == new_cgrp->root) {
|
|
if (cgrp1 != new_cgrp)
|
|
return false;
|
|
} else {
|
|
if (cgrp1 != cgrp2)
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* find_existing_css_set - init css array and find the matching css_set
|
|
* @old_cset: the css_set that we're using before the cgroup transition
|
|
* @cgrp: the cgroup that we're moving into
|
|
* @template: out param for the new set of csses, should be clear on entry
|
|
*/
|
|
static struct css_set *find_existing_css_set(struct css_set *old_cset,
|
|
struct cgroup *cgrp,
|
|
struct cgroup_subsys_state *template[])
|
|
{
|
|
struct cgroup_root *root = cgrp->root;
|
|
struct cgroup_subsys *ss;
|
|
struct css_set *cset;
|
|
unsigned long key;
|
|
int i;
|
|
|
|
/*
|
|
* Build the set of subsystem state objects that we want to see in the
|
|
* new css_set. while subsystems can change globally, the entries here
|
|
* won't change, so no need for locking.
|
|
*/
|
|
for_each_subsys(ss, i) {
|
|
if (root->subsys_mask & (1UL << i)) {
|
|
/*
|
|
* @ss is in this hierarchy, so we want the
|
|
* effective css from @cgrp.
|
|
*/
|
|
template[i] = cgroup_e_css(cgrp, ss);
|
|
} else {
|
|
/*
|
|
* @ss is not in this hierarchy, so we don't want
|
|
* to change the css.
|
|
*/
|
|
template[i] = old_cset->subsys[i];
|
|
}
|
|
}
|
|
|
|
key = css_set_hash(template);
|
|
hash_for_each_possible(css_set_table, cset, hlist, key) {
|
|
if (!compare_css_sets(cset, old_cset, cgrp, template))
|
|
continue;
|
|
|
|
/* This css_set matches what we need */
|
|
return cset;
|
|
}
|
|
|
|
/* No existing cgroup group matched */
|
|
return NULL;
|
|
}
|
|
|
|
static void free_cgrp_cset_links(struct list_head *links_to_free)
|
|
{
|
|
struct cgrp_cset_link *link, *tmp_link;
|
|
|
|
list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) {
|
|
list_del(&link->cset_link);
|
|
kfree(link);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* allocate_cgrp_cset_links - allocate cgrp_cset_links
|
|
* @count: the number of links to allocate
|
|
* @tmp_links: list_head the allocated links are put on
|
|
*
|
|
* Allocate @count cgrp_cset_link structures and chain them on @tmp_links
|
|
* through ->cset_link. Returns 0 on success or -errno.
|
|
*/
|
|
static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links)
|
|
{
|
|
struct cgrp_cset_link *link;
|
|
int i;
|
|
|
|
INIT_LIST_HEAD(tmp_links);
|
|
|
|
for (i = 0; i < count; i++) {
|
|
link = kzalloc(sizeof(*link), GFP_KERNEL);
|
|
if (!link) {
|
|
free_cgrp_cset_links(tmp_links);
|
|
return -ENOMEM;
|
|
}
|
|
list_add(&link->cset_link, tmp_links);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* link_css_set - a helper function to link a css_set to a cgroup
|
|
* @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
|
|
* @cset: the css_set to be linked
|
|
* @cgrp: the destination cgroup
|
|
*/
|
|
static void link_css_set(struct list_head *tmp_links, struct css_set *cset,
|
|
struct cgroup *cgrp)
|
|
{
|
|
struct cgrp_cset_link *link;
|
|
|
|
BUG_ON(list_empty(tmp_links));
|
|
|
|
if (cgroup_on_dfl(cgrp))
|
|
cset->dfl_cgrp = cgrp;
|
|
|
|
link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link);
|
|
link->cset = cset;
|
|
link->cgrp = cgrp;
|
|
|
|
if (list_empty(&cgrp->cset_links))
|
|
cgroup_update_populated(cgrp, true);
|
|
list_move(&link->cset_link, &cgrp->cset_links);
|
|
|
|
/*
|
|
* Always add links to the tail of the list so that the list
|
|
* is sorted by order of hierarchy creation
|
|
*/
|
|
list_add_tail(&link->cgrp_link, &cset->cgrp_links);
|
|
}
|
|
|
|
/**
|
|
* find_css_set - return a new css_set with one cgroup updated
|
|
* @old_cset: the baseline css_set
|
|
* @cgrp: the cgroup to be updated
|
|
*
|
|
* Return a new css_set that's equivalent to @old_cset, but with @cgrp
|
|
* substituted into the appropriate hierarchy.
|
|
*/
|
|
static struct css_set *find_css_set(struct css_set *old_cset,
|
|
struct cgroup *cgrp)
|
|
{
|
|
struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { };
|
|
struct css_set *cset;
|
|
struct list_head tmp_links;
|
|
struct cgrp_cset_link *link;
|
|
struct cgroup_subsys *ss;
|
|
unsigned long key;
|
|
int ssid;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
/* First see if we already have a cgroup group that matches
|
|
* the desired set */
|
|
down_read(&css_set_rwsem);
|
|
cset = find_existing_css_set(old_cset, cgrp, template);
|
|
if (cset)
|
|
get_css_set(cset);
|
|
up_read(&css_set_rwsem);
|
|
|
|
if (cset)
|
|
return cset;
|
|
|
|
cset = kzalloc(sizeof(*cset), GFP_KERNEL);
|
|
if (!cset)
|
|
return NULL;
|
|
|
|
/* Allocate all the cgrp_cset_link objects that we'll need */
|
|
if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) {
|
|
kfree(cset);
|
|
return NULL;
|
|
}
|
|
|
|
atomic_set(&cset->refcount, 1);
|
|
INIT_LIST_HEAD(&cset->cgrp_links);
|
|
INIT_LIST_HEAD(&cset->tasks);
|
|
INIT_LIST_HEAD(&cset->mg_tasks);
|
|
INIT_LIST_HEAD(&cset->mg_preload_node);
|
|
INIT_LIST_HEAD(&cset->mg_node);
|
|
INIT_HLIST_NODE(&cset->hlist);
|
|
|
|
/* Copy the set of subsystem state objects generated in
|
|
* find_existing_css_set() */
|
|
memcpy(cset->subsys, template, sizeof(cset->subsys));
|
|
|
|
down_write(&css_set_rwsem);
|
|
/* Add reference counts and links from the new css_set. */
|
|
list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) {
|
|
struct cgroup *c = link->cgrp;
|
|
|
|
if (c->root == cgrp->root)
|
|
c = cgrp;
|
|
link_css_set(&tmp_links, cset, c);
|
|
}
|
|
|
|
BUG_ON(!list_empty(&tmp_links));
|
|
|
|
css_set_count++;
|
|
|
|
/* Add @cset to the hash table */
|
|
key = css_set_hash(cset->subsys);
|
|
hash_add(css_set_table, &cset->hlist, key);
|
|
|
|
for_each_subsys(ss, ssid)
|
|
list_add_tail(&cset->e_cset_node[ssid],
|
|
&cset->subsys[ssid]->cgroup->e_csets[ssid]);
|
|
|
|
up_write(&css_set_rwsem);
|
|
|
|
return cset;
|
|
}
|
|
|
|
static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
|
|
{
|
|
struct cgroup *root_cgrp = kf_root->kn->priv;
|
|
|
|
return root_cgrp->root;
|
|
}
|
|
|
|
static int cgroup_init_root_id(struct cgroup_root *root)
|
|
{
|
|
int id;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL);
|
|
if (id < 0)
|
|
return id;
|
|
|
|
root->hierarchy_id = id;
|
|
return 0;
|
|
}
|
|
|
|
static void cgroup_exit_root_id(struct cgroup_root *root)
|
|
{
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
if (root->hierarchy_id) {
|
|
idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
|
|
root->hierarchy_id = 0;
|
|
}
|
|
}
|
|
|
|
static void cgroup_free_root(struct cgroup_root *root)
|
|
{
|
|
if (root) {
|
|
/* hierarchy ID should already have been released */
|
|
WARN_ON_ONCE(root->hierarchy_id);
|
|
|
|
idr_destroy(&root->cgroup_idr);
|
|
kfree(root);
|
|
}
|
|
}
|
|
|
|
static void cgroup_destroy_root(struct cgroup_root *root)
|
|
{
|
|
struct cgroup *cgrp = &root->cgrp;
|
|
struct cgrp_cset_link *link, *tmp_link;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
BUG_ON(atomic_read(&root->nr_cgrps));
|
|
BUG_ON(!list_empty(&cgrp->self.children));
|
|
|
|
/* Rebind all subsystems back to the default hierarchy */
|
|
rebind_subsystems(&cgrp_dfl_root, root->subsys_mask);
|
|
|
|
/*
|
|
* Release all the links from cset_links to this hierarchy's
|
|
* root cgroup
|
|
*/
|
|
down_write(&css_set_rwsem);
|
|
|
|
list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) {
|
|
list_del(&link->cset_link);
|
|
list_del(&link->cgrp_link);
|
|
kfree(link);
|
|
}
|
|
up_write(&css_set_rwsem);
|
|
|
|
if (!list_empty(&root->root_list)) {
|
|
list_del(&root->root_list);
|
|
cgroup_root_count--;
|
|
}
|
|
|
|
cgroup_exit_root_id(root);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
kernfs_destroy_root(root->kf_root);
|
|
cgroup_free_root(root);
|
|
}
|
|
|
|
/* look up cgroup associated with given css_set on the specified hierarchy */
|
|
static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
|
|
struct cgroup_root *root)
|
|
{
|
|
struct cgroup *res = NULL;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
lockdep_assert_held(&css_set_rwsem);
|
|
|
|
if (cset == &init_css_set) {
|
|
res = &root->cgrp;
|
|
} else {
|
|
struct cgrp_cset_link *link;
|
|
|
|
list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
|
|
struct cgroup *c = link->cgrp;
|
|
|
|
if (c->root == root) {
|
|
res = c;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
BUG_ON(!res);
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* Return the cgroup for "task" from the given hierarchy. Must be
|
|
* called with cgroup_mutex and css_set_rwsem held.
|
|
*/
|
|
static struct cgroup *task_cgroup_from_root(struct task_struct *task,
|
|
struct cgroup_root *root)
|
|
{
|
|
/*
|
|
* No need to lock the task - since we hold cgroup_mutex the
|
|
* task can't change groups, so the only thing that can happen
|
|
* is that it exits and its css is set back to init_css_set.
|
|
*/
|
|
return cset_cgroup_from_root(task_css_set(task), root);
|
|
}
|
|
|
|
/*
|
|
* A task must hold cgroup_mutex to modify cgroups.
|
|
*
|
|
* Any task can increment and decrement the count field without lock.
|
|
* So in general, code holding cgroup_mutex can't rely on the count
|
|
* field not changing. However, if the count goes to zero, then only
|
|
* cgroup_attach_task() can increment it again. Because a count of zero
|
|
* means that no tasks are currently attached, therefore there is no
|
|
* way a task attached to that cgroup can fork (the other way to
|
|
* increment the count). So code holding cgroup_mutex can safely
|
|
* assume that if the count is zero, it will stay zero. Similarly, if
|
|
* a task holds cgroup_mutex on a cgroup with zero count, it
|
|
* knows that the cgroup won't be removed, as cgroup_rmdir()
|
|
* needs that mutex.
|
|
*
|
|
* A cgroup can only be deleted if both its 'count' of using tasks
|
|
* is zero, and its list of 'children' cgroups is empty. Since all
|
|
* tasks in the system use _some_ cgroup, and since there is always at
|
|
* least one task in the system (init, pid == 1), therefore, root cgroup
|
|
* always has either children cgroups and/or using tasks. So we don't
|
|
* need a special hack to ensure that root cgroup cannot be deleted.
|
|
*
|
|
* P.S. One more locking exception. RCU is used to guard the
|
|
* update of a tasks cgroup pointer by cgroup_attach_task()
|
|
*/
|
|
|
|
static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
|
|
static const struct file_operations proc_cgroupstats_operations;
|
|
|
|
static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
|
|
char *buf)
|
|
{
|
|
struct cgroup_subsys *ss = cft->ss;
|
|
|
|
if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) &&
|
|
!(cgrp->root->flags & CGRP_ROOT_NOPREFIX))
|
|
snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s",
|
|
cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name,
|
|
cft->name);
|
|
else
|
|
strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
|
|
return buf;
|
|
}
|
|
|
|
/**
|
|
* cgroup_file_mode - deduce file mode of a control file
|
|
* @cft: the control file in question
|
|
*
|
|
* S_IRUGO for read, S_IWUSR for write.
|
|
*/
|
|
static umode_t cgroup_file_mode(const struct cftype *cft)
|
|
{
|
|
umode_t mode = 0;
|
|
|
|
if (cft->read_u64 || cft->read_s64 || cft->seq_show)
|
|
mode |= S_IRUGO;
|
|
|
|
if (cft->write_u64 || cft->write_s64 || cft->write) {
|
|
if (cft->flags & CFTYPE_WORLD_WRITABLE)
|
|
mode |= S_IWUGO;
|
|
else
|
|
mode |= S_IWUSR;
|
|
}
|
|
|
|
return mode;
|
|
}
|
|
|
|
static void cgroup_get(struct cgroup *cgrp)
|
|
{
|
|
WARN_ON_ONCE(cgroup_is_dead(cgrp));
|
|
css_get(&cgrp->self);
|
|
}
|
|
|
|
static bool cgroup_tryget(struct cgroup *cgrp)
|
|
{
|
|
return css_tryget(&cgrp->self);
|
|
}
|
|
|
|
static void cgroup_put(struct cgroup *cgrp)
|
|
{
|
|
css_put(&cgrp->self);
|
|
}
|
|
|
|
/**
|
|
* cgroup_calc_child_subsys_mask - calculate child_subsys_mask
|
|
* @cgrp: the target cgroup
|
|
* @subtree_control: the new subtree_control mask to consider
|
|
*
|
|
* On the default hierarchy, a subsystem may request other subsystems to be
|
|
* enabled together through its ->depends_on mask. In such cases, more
|
|
* subsystems than specified in "cgroup.subtree_control" may be enabled.
|
|
*
|
|
* This function calculates which subsystems need to be enabled if
|
|
* @subtree_control is to be applied to @cgrp. The returned mask is always
|
|
* a superset of @subtree_control and follows the usual hierarchy rules.
|
|
*/
|
|
static unsigned long cgroup_calc_child_subsys_mask(struct cgroup *cgrp,
|
|
unsigned long subtree_control)
|
|
{
|
|
struct cgroup *parent = cgroup_parent(cgrp);
|
|
unsigned long cur_ss_mask = subtree_control;
|
|
struct cgroup_subsys *ss;
|
|
int ssid;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
if (!cgroup_on_dfl(cgrp))
|
|
return cur_ss_mask;
|
|
|
|
while (true) {
|
|
unsigned long new_ss_mask = cur_ss_mask;
|
|
|
|
for_each_subsys_which(ss, ssid, &cur_ss_mask)
|
|
new_ss_mask |= ss->depends_on;
|
|
|
|
/*
|
|
* Mask out subsystems which aren't available. This can
|
|
* happen only if some depended-upon subsystems were bound
|
|
* to non-default hierarchies.
|
|
*/
|
|
if (parent)
|
|
new_ss_mask &= parent->child_subsys_mask;
|
|
else
|
|
new_ss_mask &= cgrp->root->subsys_mask;
|
|
|
|
if (new_ss_mask == cur_ss_mask)
|
|
break;
|
|
cur_ss_mask = new_ss_mask;
|
|
}
|
|
|
|
return cur_ss_mask;
|
|
}
|
|
|
|
/**
|
|
* cgroup_refresh_child_subsys_mask - update child_subsys_mask
|
|
* @cgrp: the target cgroup
|
|
*
|
|
* Update @cgrp->child_subsys_mask according to the current
|
|
* @cgrp->subtree_control using cgroup_calc_child_subsys_mask().
|
|
*/
|
|
static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp)
|
|
{
|
|
cgrp->child_subsys_mask =
|
|
cgroup_calc_child_subsys_mask(cgrp, cgrp->subtree_control);
|
|
}
|
|
|
|
/**
|
|
* cgroup_kn_unlock - unlocking helper for cgroup kernfs methods
|
|
* @kn: the kernfs_node being serviced
|
|
*
|
|
* This helper undoes cgroup_kn_lock_live() and should be invoked before
|
|
* the method finishes if locking succeeded. Note that once this function
|
|
* returns the cgroup returned by cgroup_kn_lock_live() may become
|
|
* inaccessible any time. If the caller intends to continue to access the
|
|
* cgroup, it should pin it before invoking this function.
|
|
*/
|
|
static void cgroup_kn_unlock(struct kernfs_node *kn)
|
|
{
|
|
struct cgroup *cgrp;
|
|
|
|
if (kernfs_type(kn) == KERNFS_DIR)
|
|
cgrp = kn->priv;
|
|
else
|
|
cgrp = kn->parent->priv;
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
kernfs_unbreak_active_protection(kn);
|
|
cgroup_put(cgrp);
|
|
}
|
|
|
|
/**
|
|
* cgroup_kn_lock_live - locking helper for cgroup kernfs methods
|
|
* @kn: the kernfs_node being serviced
|
|
*
|
|
* This helper is to be used by a cgroup kernfs method currently servicing
|
|
* @kn. It breaks the active protection, performs cgroup locking and
|
|
* verifies that the associated cgroup is alive. Returns the cgroup if
|
|
* alive; otherwise, %NULL. A successful return should be undone by a
|
|
* matching cgroup_kn_unlock() invocation.
|
|
*
|
|
* Any cgroup kernfs method implementation which requires locking the
|
|
* associated cgroup should use this helper. It avoids nesting cgroup
|
|
* locking under kernfs active protection and allows all kernfs operations
|
|
* including self-removal.
|
|
*/
|
|
static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn)
|
|
{
|
|
struct cgroup *cgrp;
|
|
|
|
if (kernfs_type(kn) == KERNFS_DIR)
|
|
cgrp = kn->priv;
|
|
else
|
|
cgrp = kn->parent->priv;
|
|
|
|
/*
|
|
* We're gonna grab cgroup_mutex which nests outside kernfs
|
|
* active_ref. cgroup liveliness check alone provides enough
|
|
* protection against removal. Ensure @cgrp stays accessible and
|
|
* break the active_ref protection.
|
|
*/
|
|
if (!cgroup_tryget(cgrp))
|
|
return NULL;
|
|
kernfs_break_active_protection(kn);
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
if (!cgroup_is_dead(cgrp))
|
|
return cgrp;
|
|
|
|
cgroup_kn_unlock(kn);
|
|
return NULL;
|
|
}
|
|
|
|
static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
|
|
{
|
|
char name[CGROUP_FILE_NAME_MAX];
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name));
|
|
}
|
|
|
|
/**
|
|
* css_clear_dir - remove subsys files in a cgroup directory
|
|
* @css: taget css
|
|
* @cgrp_override: specify if target cgroup is different from css->cgroup
|
|
*/
|
|
static void css_clear_dir(struct cgroup_subsys_state *css,
|
|
struct cgroup *cgrp_override)
|
|
{
|
|
struct cgroup *cgrp = cgrp_override ?: css->cgroup;
|
|
struct cftype *cfts;
|
|
|
|
list_for_each_entry(cfts, &css->ss->cfts, node)
|
|
cgroup_addrm_files(css, cgrp, cfts, false);
|
|
}
|
|
|
|
/**
|
|
* css_populate_dir - create subsys files in a cgroup directory
|
|
* @css: target css
|
|
* @cgrp_overried: specify if target cgroup is different from css->cgroup
|
|
*
|
|
* On failure, no file is added.
|
|
*/
|
|
static int css_populate_dir(struct cgroup_subsys_state *css,
|
|
struct cgroup *cgrp_override)
|
|
{
|
|
struct cgroup *cgrp = cgrp_override ?: css->cgroup;
|
|
struct cftype *cfts, *failed_cfts;
|
|
int ret;
|
|
|
|
if (!css->ss) {
|
|
if (cgroup_on_dfl(cgrp))
|
|
cfts = cgroup_dfl_base_files;
|
|
else
|
|
cfts = cgroup_legacy_base_files;
|
|
|
|
return cgroup_addrm_files(&cgrp->self, cgrp, cfts, true);
|
|
}
|
|
|
|
list_for_each_entry(cfts, &css->ss->cfts, node) {
|
|
ret = cgroup_addrm_files(css, cgrp, cfts, true);
|
|
if (ret < 0) {
|
|
failed_cfts = cfts;
|
|
goto err;
|
|
}
|
|
}
|
|
return 0;
|
|
err:
|
|
list_for_each_entry(cfts, &css->ss->cfts, node) {
|
|
if (cfts == failed_cfts)
|
|
break;
|
|
cgroup_addrm_files(css, cgrp, cfts, false);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static int rebind_subsystems(struct cgroup_root *dst_root,
|
|
unsigned long ss_mask)
|
|
{
|
|
struct cgroup *dcgrp = &dst_root->cgrp;
|
|
struct cgroup_subsys *ss;
|
|
unsigned long tmp_ss_mask;
|
|
int ssid, i, ret;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
for_each_subsys_which(ss, ssid, &ss_mask) {
|
|
/* if @ss has non-root csses attached to it, can't move */
|
|
if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss)))
|
|
return -EBUSY;
|
|
|
|
/* can't move between two non-dummy roots either */
|
|
if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root)
|
|
return -EBUSY;
|
|
}
|
|
|
|
/* skip creating root files on dfl_root for inhibited subsystems */
|
|
tmp_ss_mask = ss_mask;
|
|
if (dst_root == &cgrp_dfl_root)
|
|
tmp_ss_mask &= ~cgrp_dfl_root_inhibit_ss_mask;
|
|
|
|
for_each_subsys_which(ss, ssid, &tmp_ss_mask) {
|
|
struct cgroup *scgrp = &ss->root->cgrp;
|
|
int tssid;
|
|
|
|
ret = css_populate_dir(cgroup_css(scgrp, ss), dcgrp);
|
|
if (!ret)
|
|
continue;
|
|
|
|
/*
|
|
* Rebinding back to the default root is not allowed to
|
|
* fail. Using both default and non-default roots should
|
|
* be rare. Moving subsystems back and forth even more so.
|
|
* Just warn about it and continue.
|
|
*/
|
|
if (dst_root == &cgrp_dfl_root) {
|
|
if (cgrp_dfl_root_visible) {
|
|
pr_warn("failed to create files (%d) while rebinding 0x%lx to default root\n",
|
|
ret, ss_mask);
|
|
pr_warn("you may retry by moving them to a different hierarchy and unbinding\n");
|
|
}
|
|
continue;
|
|
}
|
|
|
|
for_each_subsys_which(ss, tssid, &tmp_ss_mask) {
|
|
if (tssid == ssid)
|
|
break;
|
|
css_clear_dir(cgroup_css(scgrp, ss), dcgrp);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Nothing can fail from this point on. Remove files for the
|
|
* removed subsystems and rebind each subsystem.
|
|
*/
|
|
for_each_subsys_which(ss, ssid, &ss_mask) {
|
|
struct cgroup_root *src_root = ss->root;
|
|
struct cgroup *scgrp = &src_root->cgrp;
|
|
struct cgroup_subsys_state *css = cgroup_css(scgrp, ss);
|
|
struct css_set *cset;
|
|
|
|
WARN_ON(!css || cgroup_css(dcgrp, ss));
|
|
|
|
css_clear_dir(css, NULL);
|
|
|
|
RCU_INIT_POINTER(scgrp->subsys[ssid], NULL);
|
|
rcu_assign_pointer(dcgrp->subsys[ssid], css);
|
|
ss->root = dst_root;
|
|
css->cgroup = dcgrp;
|
|
|
|
down_write(&css_set_rwsem);
|
|
hash_for_each(css_set_table, i, cset, hlist)
|
|
list_move_tail(&cset->e_cset_node[ss->id],
|
|
&dcgrp->e_csets[ss->id]);
|
|
up_write(&css_set_rwsem);
|
|
|
|
src_root->subsys_mask &= ~(1 << ssid);
|
|
scgrp->subtree_control &= ~(1 << ssid);
|
|
cgroup_refresh_child_subsys_mask(scgrp);
|
|
|
|
/* default hierarchy doesn't enable controllers by default */
|
|
dst_root->subsys_mask |= 1 << ssid;
|
|
if (dst_root == &cgrp_dfl_root) {
|
|
static_branch_enable(cgroup_subsys_on_dfl_key[ssid]);
|
|
} else {
|
|
dcgrp->subtree_control |= 1 << ssid;
|
|
cgroup_refresh_child_subsys_mask(dcgrp);
|
|
static_branch_disable(cgroup_subsys_on_dfl_key[ssid]);
|
|
}
|
|
|
|
if (ss->bind)
|
|
ss->bind(css);
|
|
}
|
|
|
|
kernfs_activate(dcgrp->kn);
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_show_options(struct seq_file *seq,
|
|
struct kernfs_root *kf_root)
|
|
{
|
|
struct cgroup_root *root = cgroup_root_from_kf(kf_root);
|
|
struct cgroup_subsys *ss;
|
|
int ssid;
|
|
|
|
if (root != &cgrp_dfl_root)
|
|
for_each_subsys(ss, ssid)
|
|
if (root->subsys_mask & (1 << ssid))
|
|
seq_show_option(seq, ss->legacy_name, NULL);
|
|
if (root->flags & CGRP_ROOT_NOPREFIX)
|
|
seq_puts(seq, ",noprefix");
|
|
if (root->flags & CGRP_ROOT_XATTR)
|
|
seq_puts(seq, ",xattr");
|
|
|
|
spin_lock(&release_agent_path_lock);
|
|
if (strlen(root->release_agent_path))
|
|
seq_show_option(seq, "release_agent",
|
|
root->release_agent_path);
|
|
spin_unlock(&release_agent_path_lock);
|
|
|
|
if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
|
|
seq_puts(seq, ",clone_children");
|
|
if (strlen(root->name))
|
|
seq_show_option(seq, "name", root->name);
|
|
return 0;
|
|
}
|
|
|
|
struct cgroup_sb_opts {
|
|
unsigned long subsys_mask;
|
|
unsigned int flags;
|
|
char *release_agent;
|
|
bool cpuset_clone_children;
|
|
char *name;
|
|
/* User explicitly requested empty subsystem */
|
|
bool none;
|
|
};
|
|
|
|
static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
|
|
{
|
|
char *token, *o = data;
|
|
bool all_ss = false, one_ss = false;
|
|
unsigned long mask = -1UL;
|
|
struct cgroup_subsys *ss;
|
|
int nr_opts = 0;
|
|
int i;
|
|
|
|
#ifdef CONFIG_CPUSETS
|
|
mask = ~(1U << cpuset_cgrp_id);
|
|
#endif
|
|
|
|
memset(opts, 0, sizeof(*opts));
|
|
|
|
while ((token = strsep(&o, ",")) != NULL) {
|
|
nr_opts++;
|
|
|
|
if (!*token)
|
|
return -EINVAL;
|
|
if (!strcmp(token, "none")) {
|
|
/* Explicitly have no subsystems */
|
|
opts->none = true;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "all")) {
|
|
/* Mutually exclusive option 'all' + subsystem name */
|
|
if (one_ss)
|
|
return -EINVAL;
|
|
all_ss = true;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "__DEVEL__sane_behavior")) {
|
|
opts->flags |= CGRP_ROOT_SANE_BEHAVIOR;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "noprefix")) {
|
|
opts->flags |= CGRP_ROOT_NOPREFIX;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "clone_children")) {
|
|
opts->cpuset_clone_children = true;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "xattr")) {
|
|
opts->flags |= CGRP_ROOT_XATTR;
|
|
continue;
|
|
}
|
|
if (!strncmp(token, "release_agent=", 14)) {
|
|
/* Specifying two release agents is forbidden */
|
|
if (opts->release_agent)
|
|
return -EINVAL;
|
|
opts->release_agent =
|
|
kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
|
|
if (!opts->release_agent)
|
|
return -ENOMEM;
|
|
continue;
|
|
}
|
|
if (!strncmp(token, "name=", 5)) {
|
|
const char *name = token + 5;
|
|
/* Can't specify an empty name */
|
|
if (!strlen(name))
|
|
return -EINVAL;
|
|
/* Must match [\w.-]+ */
|
|
for (i = 0; i < strlen(name); i++) {
|
|
char c = name[i];
|
|
if (isalnum(c))
|
|
continue;
|
|
if ((c == '.') || (c == '-') || (c == '_'))
|
|
continue;
|
|
return -EINVAL;
|
|
}
|
|
/* Specifying two names is forbidden */
|
|
if (opts->name)
|
|
return -EINVAL;
|
|
opts->name = kstrndup(name,
|
|
MAX_CGROUP_ROOT_NAMELEN - 1,
|
|
GFP_KERNEL);
|
|
if (!opts->name)
|
|
return -ENOMEM;
|
|
|
|
continue;
|
|
}
|
|
|
|
for_each_subsys(ss, i) {
|
|
if (strcmp(token, ss->legacy_name))
|
|
continue;
|
|
if (!cgroup_ssid_enabled(i))
|
|
continue;
|
|
|
|
/* Mutually exclusive option 'all' + subsystem name */
|
|
if (all_ss)
|
|
return -EINVAL;
|
|
opts->subsys_mask |= (1 << i);
|
|
one_ss = true;
|
|
|
|
break;
|
|
}
|
|
if (i == CGROUP_SUBSYS_COUNT)
|
|
return -ENOENT;
|
|
}
|
|
|
|
if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) {
|
|
pr_warn("sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n");
|
|
if (nr_opts != 1) {
|
|
pr_err("sane_behavior: no other mount options allowed\n");
|
|
return -EINVAL;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* If the 'all' option was specified select all the subsystems,
|
|
* otherwise if 'none', 'name=' and a subsystem name options were
|
|
* not specified, let's default to 'all'
|
|
*/
|
|
if (all_ss || (!one_ss && !opts->none && !opts->name))
|
|
for_each_subsys(ss, i)
|
|
if (cgroup_ssid_enabled(i))
|
|
opts->subsys_mask |= (1 << i);
|
|
|
|
/*
|
|
* We either have to specify by name or by subsystems. (So all
|
|
* empty hierarchies must have a name).
|
|
*/
|
|
if (!opts->subsys_mask && !opts->name)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Option noprefix was introduced just for backward compatibility
|
|
* with the old cpuset, so we allow noprefix only if mounting just
|
|
* the cpuset subsystem.
|
|
*/
|
|
if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
|
|
return -EINVAL;
|
|
|
|
/* Can't specify "none" and some subsystems */
|
|
if (opts->subsys_mask && opts->none)
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
|
|
{
|
|
int ret = 0;
|
|
struct cgroup_root *root = cgroup_root_from_kf(kf_root);
|
|
struct cgroup_sb_opts opts;
|
|
unsigned long added_mask, removed_mask;
|
|
|
|
if (root == &cgrp_dfl_root) {
|
|
pr_err("remount is not allowed\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/* See what subsystems are wanted */
|
|
ret = parse_cgroupfs_options(data, &opts);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
|
|
pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
|
|
task_tgid_nr(current), current->comm);
|
|
|
|
added_mask = opts.subsys_mask & ~root->subsys_mask;
|
|
removed_mask = root->subsys_mask & ~opts.subsys_mask;
|
|
|
|
/* Don't allow flags or name to change at remount */
|
|
if ((opts.flags ^ root->flags) ||
|
|
(opts.name && strcmp(opts.name, root->name))) {
|
|
pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
|
|
opts.flags, opts.name ?: "", root->flags, root->name);
|
|
ret = -EINVAL;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* remounting is not allowed for populated hierarchies */
|
|
if (!list_empty(&root->cgrp.self.children)) {
|
|
ret = -EBUSY;
|
|
goto out_unlock;
|
|
}
|
|
|
|
ret = rebind_subsystems(root, added_mask);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
rebind_subsystems(&cgrp_dfl_root, removed_mask);
|
|
|
|
if (opts.release_agent) {
|
|
spin_lock(&release_agent_path_lock);
|
|
strcpy(root->release_agent_path, opts.release_agent);
|
|
spin_unlock(&release_agent_path_lock);
|
|
}
|
|
out_unlock:
|
|
kfree(opts.release_agent);
|
|
kfree(opts.name);
|
|
mutex_unlock(&cgroup_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* To reduce the fork() overhead for systems that are not actually using
|
|
* their cgroups capability, we don't maintain the lists running through
|
|
* each css_set to its tasks until we see the list actually used - in other
|
|
* words after the first mount.
|
|
*/
|
|
static bool use_task_css_set_links __read_mostly;
|
|
|
|
static void cgroup_enable_task_cg_lists(void)
|
|
{
|
|
struct task_struct *p, *g;
|
|
|
|
down_write(&css_set_rwsem);
|
|
|
|
if (use_task_css_set_links)
|
|
goto out_unlock;
|
|
|
|
use_task_css_set_links = true;
|
|
|
|
/*
|
|
* We need tasklist_lock because RCU is not safe against
|
|
* while_each_thread(). Besides, a forking task that has passed
|
|
* cgroup_post_fork() without seeing use_task_css_set_links = 1
|
|
* is not guaranteed to have its child immediately visible in the
|
|
* tasklist if we walk through it with RCU.
|
|
*/
|
|
read_lock(&tasklist_lock);
|
|
do_each_thread(g, p) {
|
|
WARN_ON_ONCE(!list_empty(&p->cg_list) ||
|
|
task_css_set(p) != &init_css_set);
|
|
|
|
/*
|
|
* We should check if the process is exiting, otherwise
|
|
* it will race with cgroup_exit() in that the list
|
|
* entry won't be deleted though the process has exited.
|
|
* Do it while holding siglock so that we don't end up
|
|
* racing against cgroup_exit().
|
|
*/
|
|
spin_lock_irq(&p->sighand->siglock);
|
|
if (!(p->flags & PF_EXITING)) {
|
|
struct css_set *cset = task_css_set(p);
|
|
|
|
list_add(&p->cg_list, &cset->tasks);
|
|
get_css_set(cset);
|
|
}
|
|
spin_unlock_irq(&p->sighand->siglock);
|
|
} while_each_thread(g, p);
|
|
read_unlock(&tasklist_lock);
|
|
out_unlock:
|
|
up_write(&css_set_rwsem);
|
|
}
|
|
|
|
static void init_cgroup_housekeeping(struct cgroup *cgrp)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int ssid;
|
|
|
|
INIT_LIST_HEAD(&cgrp->self.sibling);
|
|
INIT_LIST_HEAD(&cgrp->self.children);
|
|
INIT_LIST_HEAD(&cgrp->self.files);
|
|
INIT_LIST_HEAD(&cgrp->cset_links);
|
|
INIT_LIST_HEAD(&cgrp->pidlists);
|
|
mutex_init(&cgrp->pidlist_mutex);
|
|
cgrp->self.cgroup = cgrp;
|
|
cgrp->self.flags |= CSS_ONLINE;
|
|
|
|
for_each_subsys(ss, ssid)
|
|
INIT_LIST_HEAD(&cgrp->e_csets[ssid]);
|
|
|
|
init_waitqueue_head(&cgrp->offline_waitq);
|
|
INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent);
|
|
}
|
|
|
|
static void init_cgroup_root(struct cgroup_root *root,
|
|
struct cgroup_sb_opts *opts)
|
|
{
|
|
struct cgroup *cgrp = &root->cgrp;
|
|
|
|
INIT_LIST_HEAD(&root->root_list);
|
|
atomic_set(&root->nr_cgrps, 1);
|
|
cgrp->root = root;
|
|
init_cgroup_housekeeping(cgrp);
|
|
idr_init(&root->cgroup_idr);
|
|
|
|
root->flags = opts->flags;
|
|
if (opts->release_agent)
|
|
strcpy(root->release_agent_path, opts->release_agent);
|
|
if (opts->name)
|
|
strcpy(root->name, opts->name);
|
|
if (opts->cpuset_clone_children)
|
|
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags);
|
|
}
|
|
|
|
static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask)
|
|
{
|
|
LIST_HEAD(tmp_links);
|
|
struct cgroup *root_cgrp = &root->cgrp;
|
|
struct css_set *cset;
|
|
int i, ret;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL);
|
|
if (ret < 0)
|
|
goto out;
|
|
root_cgrp->id = ret;
|
|
|
|
ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, 0,
|
|
GFP_KERNEL);
|
|
if (ret)
|
|
goto out;
|
|
|
|
/*
|
|
* We're accessing css_set_count without locking css_set_rwsem here,
|
|
* but that's OK - it can only be increased by someone holding
|
|
* cgroup_lock, and that's us. The worst that can happen is that we
|
|
* have some link structures left over
|
|
*/
|
|
ret = allocate_cgrp_cset_links(css_set_count, &tmp_links);
|
|
if (ret)
|
|
goto cancel_ref;
|
|
|
|
ret = cgroup_init_root_id(root);
|
|
if (ret)
|
|
goto cancel_ref;
|
|
|
|
root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops,
|
|
KERNFS_ROOT_CREATE_DEACTIVATED,
|
|
root_cgrp);
|
|
if (IS_ERR(root->kf_root)) {
|
|
ret = PTR_ERR(root->kf_root);
|
|
goto exit_root_id;
|
|
}
|
|
root_cgrp->kn = root->kf_root->kn;
|
|
|
|
ret = css_populate_dir(&root_cgrp->self, NULL);
|
|
if (ret)
|
|
goto destroy_root;
|
|
|
|
ret = rebind_subsystems(root, ss_mask);
|
|
if (ret)
|
|
goto destroy_root;
|
|
|
|
/*
|
|
* There must be no failure case after here, since rebinding takes
|
|
* care of subsystems' refcounts, which are explicitly dropped in
|
|
* the failure exit path.
|
|
*/
|
|
list_add(&root->root_list, &cgroup_roots);
|
|
cgroup_root_count++;
|
|
|
|
/*
|
|
* Link the root cgroup in this hierarchy into all the css_set
|
|
* objects.
|
|
*/
|
|
down_write(&css_set_rwsem);
|
|
hash_for_each(css_set_table, i, cset, hlist)
|
|
link_css_set(&tmp_links, cset, root_cgrp);
|
|
up_write(&css_set_rwsem);
|
|
|
|
BUG_ON(!list_empty(&root_cgrp->self.children));
|
|
BUG_ON(atomic_read(&root->nr_cgrps) != 1);
|
|
|
|
kernfs_activate(root_cgrp->kn);
|
|
ret = 0;
|
|
goto out;
|
|
|
|
destroy_root:
|
|
kernfs_destroy_root(root->kf_root);
|
|
root->kf_root = NULL;
|
|
exit_root_id:
|
|
cgroup_exit_root_id(root);
|
|
cancel_ref:
|
|
percpu_ref_exit(&root_cgrp->self.refcnt);
|
|
out:
|
|
free_cgrp_cset_links(&tmp_links);
|
|
return ret;
|
|
}
|
|
|
|
static struct dentry *cgroup_mount(struct file_system_type *fs_type,
|
|
int flags, const char *unused_dev_name,
|
|
void *data)
|
|
{
|
|
struct super_block *pinned_sb = NULL;
|
|
struct cgroup_subsys *ss;
|
|
struct cgroup_root *root;
|
|
struct cgroup_sb_opts opts;
|
|
struct dentry *dentry;
|
|
int ret;
|
|
int i;
|
|
bool new_sb;
|
|
|
|
/*
|
|
* The first time anyone tries to mount a cgroup, enable the list
|
|
* linking each css_set to its tasks and fix up all existing tasks.
|
|
*/
|
|
if (!use_task_css_set_links)
|
|
cgroup_enable_task_cg_lists();
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/* First find the desired set of subsystems */
|
|
ret = parse_cgroupfs_options(data, &opts);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
/* look for a matching existing root */
|
|
if (opts.flags & CGRP_ROOT_SANE_BEHAVIOR) {
|
|
cgrp_dfl_root_visible = true;
|
|
root = &cgrp_dfl_root;
|
|
cgroup_get(&root->cgrp);
|
|
ret = 0;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/*
|
|
* Destruction of cgroup root is asynchronous, so subsystems may
|
|
* still be dying after the previous unmount. Let's drain the
|
|
* dying subsystems. We just need to ensure that the ones
|
|
* unmounted previously finish dying and don't care about new ones
|
|
* starting. Testing ref liveliness is good enough.
|
|
*/
|
|
for_each_subsys(ss, i) {
|
|
if (!(opts.subsys_mask & (1 << i)) ||
|
|
ss->root == &cgrp_dfl_root)
|
|
continue;
|
|
|
|
if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
msleep(10);
|
|
ret = restart_syscall();
|
|
goto out_free;
|
|
}
|
|
cgroup_put(&ss->root->cgrp);
|
|
}
|
|
|
|
for_each_root(root) {
|
|
bool name_match = false;
|
|
|
|
if (root == &cgrp_dfl_root)
|
|
continue;
|
|
|
|
/*
|
|
* If we asked for a name then it must match. Also, if
|
|
* name matches but sybsys_mask doesn't, we should fail.
|
|
* Remember whether name matched.
|
|
*/
|
|
if (opts.name) {
|
|
if (strcmp(opts.name, root->name))
|
|
continue;
|
|
name_match = true;
|
|
}
|
|
|
|
/*
|
|
* If we asked for subsystems (or explicitly for no
|
|
* subsystems) then they must match.
|
|
*/
|
|
if ((opts.subsys_mask || opts.none) &&
|
|
(opts.subsys_mask != root->subsys_mask)) {
|
|
if (!name_match)
|
|
continue;
|
|
ret = -EBUSY;
|
|
goto out_unlock;
|
|
}
|
|
|
|
if (root->flags ^ opts.flags)
|
|
pr_warn("new mount options do not match the existing superblock, will be ignored\n");
|
|
|
|
/*
|
|
* We want to reuse @root whose lifetime is governed by its
|
|
* ->cgrp. Let's check whether @root is alive and keep it
|
|
* that way. As cgroup_kill_sb() can happen anytime, we
|
|
* want to block it by pinning the sb so that @root doesn't
|
|
* get killed before mount is complete.
|
|
*
|
|
* With the sb pinned, tryget_live can reliably indicate
|
|
* whether @root can be reused. If it's being killed,
|
|
* drain it. We can use wait_queue for the wait but this
|
|
* path is super cold. Let's just sleep a bit and retry.
|
|
*/
|
|
pinned_sb = kernfs_pin_sb(root->kf_root, NULL);
|
|
if (IS_ERR(pinned_sb) ||
|
|
!percpu_ref_tryget_live(&root->cgrp.self.refcnt)) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
if (!IS_ERR_OR_NULL(pinned_sb))
|
|
deactivate_super(pinned_sb);
|
|
msleep(10);
|
|
ret = restart_syscall();
|
|
goto out_free;
|
|
}
|
|
|
|
ret = 0;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/*
|
|
* No such thing, create a new one. name= matching without subsys
|
|
* specification is allowed for already existing hierarchies but we
|
|
* can't create new one without subsys specification.
|
|
*/
|
|
if (!opts.subsys_mask && !opts.none) {
|
|
ret = -EINVAL;
|
|
goto out_unlock;
|
|
}
|
|
|
|
root = kzalloc(sizeof(*root), GFP_KERNEL);
|
|
if (!root) {
|
|
ret = -ENOMEM;
|
|
goto out_unlock;
|
|
}
|
|
|
|
init_cgroup_root(root, &opts);
|
|
|
|
ret = cgroup_setup_root(root, opts.subsys_mask);
|
|
if (ret)
|
|
cgroup_free_root(root);
|
|
|
|
out_unlock:
|
|
mutex_unlock(&cgroup_mutex);
|
|
out_free:
|
|
kfree(opts.release_agent);
|
|
kfree(opts.name);
|
|
|
|
if (ret)
|
|
return ERR_PTR(ret);
|
|
|
|
dentry = kernfs_mount(fs_type, flags, root->kf_root,
|
|
CGROUP_SUPER_MAGIC, &new_sb);
|
|
if (IS_ERR(dentry) || !new_sb)
|
|
cgroup_put(&root->cgrp);
|
|
|
|
/*
|
|
* If @pinned_sb, we're reusing an existing root and holding an
|
|
* extra ref on its sb. Mount is complete. Put the extra ref.
|
|
*/
|
|
if (pinned_sb) {
|
|
WARN_ON(new_sb);
|
|
deactivate_super(pinned_sb);
|
|
}
|
|
|
|
return dentry;
|
|
}
|
|
|
|
static void cgroup_kill_sb(struct super_block *sb)
|
|
{
|
|
struct kernfs_root *kf_root = kernfs_root_from_sb(sb);
|
|
struct cgroup_root *root = cgroup_root_from_kf(kf_root);
|
|
|
|
/*
|
|
* If @root doesn't have any mounts or children, start killing it.
|
|
* This prevents new mounts by disabling percpu_ref_tryget_live().
|
|
* cgroup_mount() may wait for @root's release.
|
|
*
|
|
* And don't kill the default root.
|
|
*/
|
|
if (!list_empty(&root->cgrp.self.children) ||
|
|
root == &cgrp_dfl_root)
|
|
cgroup_put(&root->cgrp);
|
|
else
|
|
percpu_ref_kill(&root->cgrp.self.refcnt);
|
|
|
|
kernfs_kill_sb(sb);
|
|
}
|
|
|
|
static struct file_system_type cgroup_fs_type = {
|
|
.name = "cgroup",
|
|
.mount = cgroup_mount,
|
|
.kill_sb = cgroup_kill_sb,
|
|
};
|
|
|
|
/**
|
|
* task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
|
|
* @task: target task
|
|
* @buf: the buffer to write the path into
|
|
* @buflen: the length of the buffer
|
|
*
|
|
* Determine @task's cgroup on the first (the one with the lowest non-zero
|
|
* hierarchy_id) cgroup hierarchy and copy its path into @buf. This
|
|
* function grabs cgroup_mutex and shouldn't be used inside locks used by
|
|
* cgroup controller callbacks.
|
|
*
|
|
* Return value is the same as kernfs_path().
|
|
*/
|
|
char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
|
|
{
|
|
struct cgroup_root *root;
|
|
struct cgroup *cgrp;
|
|
int hierarchy_id = 1;
|
|
char *path = NULL;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
down_read(&css_set_rwsem);
|
|
|
|
root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id);
|
|
|
|
if (root) {
|
|
cgrp = task_cgroup_from_root(task, root);
|
|
path = cgroup_path(cgrp, buf, buflen);
|
|
} else {
|
|
/* if no hierarchy exists, everyone is in "/" */
|
|
if (strlcpy(buf, "/", buflen) < buflen)
|
|
path = buf;
|
|
}
|
|
|
|
up_read(&css_set_rwsem);
|
|
mutex_unlock(&cgroup_mutex);
|
|
return path;
|
|
}
|
|
EXPORT_SYMBOL_GPL(task_cgroup_path);
|
|
|
|
/* used to track tasks and other necessary states during migration */
|
|
struct cgroup_taskset {
|
|
/* the src and dst cset list running through cset->mg_node */
|
|
struct list_head src_csets;
|
|
struct list_head dst_csets;
|
|
|
|
/*
|
|
* Fields for cgroup_taskset_*() iteration.
|
|
*
|
|
* Before migration is committed, the target migration tasks are on
|
|
* ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of
|
|
* the csets on ->dst_csets. ->csets point to either ->src_csets
|
|
* or ->dst_csets depending on whether migration is committed.
|
|
*
|
|
* ->cur_csets and ->cur_task point to the current task position
|
|
* during iteration.
|
|
*/
|
|
struct list_head *csets;
|
|
struct css_set *cur_cset;
|
|
struct task_struct *cur_task;
|
|
};
|
|
|
|
/**
|
|
* cgroup_taskset_first - reset taskset and return the first task
|
|
* @tset: taskset of interest
|
|
*
|
|
* @tset iteration is initialized and the first task is returned.
|
|
*/
|
|
struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset)
|
|
{
|
|
tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node);
|
|
tset->cur_task = NULL;
|
|
|
|
return cgroup_taskset_next(tset);
|
|
}
|
|
|
|
/**
|
|
* cgroup_taskset_next - iterate to the next task in taskset
|
|
* @tset: taskset of interest
|
|
*
|
|
* Return the next task in @tset. Iteration must have been initialized
|
|
* with cgroup_taskset_first().
|
|
*/
|
|
struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset)
|
|
{
|
|
struct css_set *cset = tset->cur_cset;
|
|
struct task_struct *task = tset->cur_task;
|
|
|
|
while (&cset->mg_node != tset->csets) {
|
|
if (!task)
|
|
task = list_first_entry(&cset->mg_tasks,
|
|
struct task_struct, cg_list);
|
|
else
|
|
task = list_next_entry(task, cg_list);
|
|
|
|
if (&task->cg_list != &cset->mg_tasks) {
|
|
tset->cur_cset = cset;
|
|
tset->cur_task = task;
|
|
return task;
|
|
}
|
|
|
|
cset = list_next_entry(cset, mg_node);
|
|
task = NULL;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* cgroup_task_migrate - move a task from one cgroup to another.
|
|
* @old_cgrp: the cgroup @tsk is being migrated from
|
|
* @tsk: the task being migrated
|
|
* @new_cset: the new css_set @tsk is being attached to
|
|
*
|
|
* Must be called with cgroup_mutex, threadgroup and css_set_rwsem locked.
|
|
*/
|
|
static void cgroup_task_migrate(struct cgroup *old_cgrp,
|
|
struct task_struct *tsk,
|
|
struct css_set *new_cset)
|
|
{
|
|
struct css_set *old_cset;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
lockdep_assert_held(&css_set_rwsem);
|
|
|
|
/*
|
|
* We are synchronized through cgroup_threadgroup_rwsem against
|
|
* PF_EXITING setting such that we can't race against cgroup_exit()
|
|
* changing the css_set to init_css_set and dropping the old one.
|
|
*/
|
|
WARN_ON_ONCE(tsk->flags & PF_EXITING);
|
|
old_cset = task_css_set(tsk);
|
|
|
|
get_css_set(new_cset);
|
|
rcu_assign_pointer(tsk->cgroups, new_cset);
|
|
|
|
/*
|
|
* Use move_tail so that cgroup_taskset_first() still returns the
|
|
* leader after migration. This works because cgroup_migrate()
|
|
* ensures that the dst_cset of the leader is the first on the
|
|
* tset's dst_csets list.
|
|
*/
|
|
list_move_tail(&tsk->cg_list, &new_cset->mg_tasks);
|
|
|
|
/*
|
|
* We just gained a reference on old_cset by taking it from the
|
|
* task. As trading it for new_cset is protected by cgroup_mutex,
|
|
* we're safe to drop it here; it will be freed under RCU.
|
|
*/
|
|
put_css_set_locked(old_cset);
|
|
}
|
|
|
|
/**
|
|
* cgroup_migrate_finish - cleanup after attach
|
|
* @preloaded_csets: list of preloaded css_sets
|
|
*
|
|
* Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See
|
|
* those functions for details.
|
|
*/
|
|
static void cgroup_migrate_finish(struct list_head *preloaded_csets)
|
|
{
|
|
struct css_set *cset, *tmp_cset;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
down_write(&css_set_rwsem);
|
|
list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) {
|
|
cset->mg_src_cgrp = NULL;
|
|
cset->mg_dst_cset = NULL;
|
|
list_del_init(&cset->mg_preload_node);
|
|
put_css_set_locked(cset);
|
|
}
|
|
up_write(&css_set_rwsem);
|
|
}
|
|
|
|
/**
|
|
* cgroup_migrate_add_src - add a migration source css_set
|
|
* @src_cset: the source css_set to add
|
|
* @dst_cgrp: the destination cgroup
|
|
* @preloaded_csets: list of preloaded css_sets
|
|
*
|
|
* Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin
|
|
* @src_cset and add it to @preloaded_csets, which should later be cleaned
|
|
* up by cgroup_migrate_finish().
|
|
*
|
|
* This function may be called without holding cgroup_threadgroup_rwsem
|
|
* even if the target is a process. Threads may be created and destroyed
|
|
* but as long as cgroup_mutex is not dropped, no new css_set can be put
|
|
* into play and the preloaded css_sets are guaranteed to cover all
|
|
* migrations.
|
|
*/
|
|
static void cgroup_migrate_add_src(struct css_set *src_cset,
|
|
struct cgroup *dst_cgrp,
|
|
struct list_head *preloaded_csets)
|
|
{
|
|
struct cgroup *src_cgrp;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
lockdep_assert_held(&css_set_rwsem);
|
|
|
|
src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root);
|
|
|
|
if (!list_empty(&src_cset->mg_preload_node))
|
|
return;
|
|
|
|
WARN_ON(src_cset->mg_src_cgrp);
|
|
WARN_ON(!list_empty(&src_cset->mg_tasks));
|
|
WARN_ON(!list_empty(&src_cset->mg_node));
|
|
|
|
src_cset->mg_src_cgrp = src_cgrp;
|
|
get_css_set(src_cset);
|
|
list_add(&src_cset->mg_preload_node, preloaded_csets);
|
|
}
|
|
|
|
/**
|
|
* cgroup_migrate_prepare_dst - prepare destination css_sets for migration
|
|
* @dst_cgrp: the destination cgroup (may be %NULL)
|
|
* @preloaded_csets: list of preloaded source css_sets
|
|
*
|
|
* Tasks are about to be moved to @dst_cgrp and all the source css_sets
|
|
* have been preloaded to @preloaded_csets. This function looks up and
|
|
* pins all destination css_sets, links each to its source, and append them
|
|
* to @preloaded_csets. If @dst_cgrp is %NULL, the destination of each
|
|
* source css_set is assumed to be its cgroup on the default hierarchy.
|
|
*
|
|
* This function must be called after cgroup_migrate_add_src() has been
|
|
* called on each migration source css_set. After migration is performed
|
|
* using cgroup_migrate(), cgroup_migrate_finish() must be called on
|
|
* @preloaded_csets.
|
|
*/
|
|
static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp,
|
|
struct list_head *preloaded_csets)
|
|
{
|
|
LIST_HEAD(csets);
|
|
struct css_set *src_cset, *tmp_cset;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
/*
|
|
* Except for the root, child_subsys_mask must be zero for a cgroup
|
|
* with tasks so that child cgroups don't compete against tasks.
|
|
*/
|
|
if (dst_cgrp && cgroup_on_dfl(dst_cgrp) && cgroup_parent(dst_cgrp) &&
|
|
dst_cgrp->child_subsys_mask)
|
|
return -EBUSY;
|
|
|
|
/* look up the dst cset for each src cset and link it to src */
|
|
list_for_each_entry_safe(src_cset, tmp_cset, preloaded_csets, mg_preload_node) {
|
|
struct css_set *dst_cset;
|
|
|
|
dst_cset = find_css_set(src_cset,
|
|
dst_cgrp ?: src_cset->dfl_cgrp);
|
|
if (!dst_cset)
|
|
goto err;
|
|
|
|
WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset);
|
|
|
|
/*
|
|
* If src cset equals dst, it's noop. Drop the src.
|
|
* cgroup_migrate() will skip the cset too. Note that we
|
|
* can't handle src == dst as some nodes are used by both.
|
|
*/
|
|
if (src_cset == dst_cset) {
|
|
src_cset->mg_src_cgrp = NULL;
|
|
list_del_init(&src_cset->mg_preload_node);
|
|
put_css_set(src_cset);
|
|
put_css_set(dst_cset);
|
|
continue;
|
|
}
|
|
|
|
src_cset->mg_dst_cset = dst_cset;
|
|
|
|
if (list_empty(&dst_cset->mg_preload_node))
|
|
list_add(&dst_cset->mg_preload_node, &csets);
|
|
else
|
|
put_css_set(dst_cset);
|
|
}
|
|
|
|
list_splice_tail(&csets, preloaded_csets);
|
|
return 0;
|
|
err:
|
|
cgroup_migrate_finish(&csets);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/**
|
|
* cgroup_migrate - migrate a process or task to a cgroup
|
|
* @cgrp: the destination cgroup
|
|
* @leader: the leader of the process or the task to migrate
|
|
* @threadgroup: whether @leader points to the whole process or a single task
|
|
*
|
|
* Migrate a process or task denoted by @leader to @cgrp. If migrating a
|
|
* process, the caller must be holding cgroup_threadgroup_rwsem. The
|
|
* caller is also responsible for invoking cgroup_migrate_add_src() and
|
|
* cgroup_migrate_prepare_dst() on the targets before invoking this
|
|
* function and following up with cgroup_migrate_finish().
|
|
*
|
|
* As long as a controller's ->can_attach() doesn't fail, this function is
|
|
* guaranteed to succeed. This means that, excluding ->can_attach()
|
|
* failure, when migrating multiple targets, the success or failure can be
|
|
* decided for all targets by invoking group_migrate_prepare_dst() before
|
|
* actually starting migrating.
|
|
*/
|
|
static int cgroup_migrate(struct cgroup *cgrp, struct task_struct *leader,
|
|
bool threadgroup)
|
|
{
|
|
struct cgroup_taskset tset = {
|
|
.src_csets = LIST_HEAD_INIT(tset.src_csets),
|
|
.dst_csets = LIST_HEAD_INIT(tset.dst_csets),
|
|
.csets = &tset.src_csets,
|
|
};
|
|
struct cgroup_subsys_state *css, *failed_css = NULL;
|
|
struct css_set *cset, *tmp_cset;
|
|
struct task_struct *task, *tmp_task;
|
|
int i, ret;
|
|
|
|
/*
|
|
* Prevent freeing of tasks while we take a snapshot. Tasks that are
|
|
* already PF_EXITING could be freed from underneath us unless we
|
|
* take an rcu_read_lock.
|
|
*/
|
|
down_write(&css_set_rwsem);
|
|
rcu_read_lock();
|
|
task = leader;
|
|
do {
|
|
/* @task either already exited or can't exit until the end */
|
|
if (task->flags & PF_EXITING)
|
|
goto next;
|
|
|
|
/* leave @task alone if post_fork() hasn't linked it yet */
|
|
if (list_empty(&task->cg_list))
|
|
goto next;
|
|
|
|
cset = task_css_set(task);
|
|
if (!cset->mg_src_cgrp)
|
|
goto next;
|
|
|
|
/*
|
|
* cgroup_taskset_first() must always return the leader.
|
|
* Take care to avoid disturbing the ordering.
|
|
*/
|
|
list_move_tail(&task->cg_list, &cset->mg_tasks);
|
|
if (list_empty(&cset->mg_node))
|
|
list_add_tail(&cset->mg_node, &tset.src_csets);
|
|
if (list_empty(&cset->mg_dst_cset->mg_node))
|
|
list_move_tail(&cset->mg_dst_cset->mg_node,
|
|
&tset.dst_csets);
|
|
next:
|
|
if (!threadgroup)
|
|
break;
|
|
} while_each_thread(leader, task);
|
|
rcu_read_unlock();
|
|
up_write(&css_set_rwsem);
|
|
|
|
/* methods shouldn't be called if no task is actually migrating */
|
|
if (list_empty(&tset.src_csets))
|
|
return 0;
|
|
|
|
/* check that we can legitimately attach to the cgroup */
|
|
for_each_e_css(css, i, cgrp) {
|
|
if (css->ss->can_attach) {
|
|
ret = css->ss->can_attach(css, &tset);
|
|
if (ret) {
|
|
failed_css = css;
|
|
goto out_cancel_attach;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Now that we're guaranteed success, proceed to move all tasks to
|
|
* the new cgroup. There are no failure cases after here, so this
|
|
* is the commit point.
|
|
*/
|
|
down_write(&css_set_rwsem);
|
|
list_for_each_entry(cset, &tset.src_csets, mg_node) {
|
|
list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list)
|
|
cgroup_task_migrate(cset->mg_src_cgrp, task,
|
|
cset->mg_dst_cset);
|
|
}
|
|
up_write(&css_set_rwsem);
|
|
|
|
/*
|
|
* Migration is committed, all target tasks are now on dst_csets.
|
|
* Nothing is sensitive to fork() after this point. Notify
|
|
* controllers that migration is complete.
|
|
*/
|
|
tset.csets = &tset.dst_csets;
|
|
|
|
for_each_e_css(css, i, cgrp)
|
|
if (css->ss->attach)
|
|
css->ss->attach(css, &tset);
|
|
|
|
ret = 0;
|
|
goto out_release_tset;
|
|
|
|
out_cancel_attach:
|
|
for_each_e_css(css, i, cgrp) {
|
|
if (css == failed_css)
|
|
break;
|
|
if (css->ss->cancel_attach)
|
|
css->ss->cancel_attach(css, &tset);
|
|
}
|
|
out_release_tset:
|
|
down_write(&css_set_rwsem);
|
|
list_splice_init(&tset.dst_csets, &tset.src_csets);
|
|
list_for_each_entry_safe(cset, tmp_cset, &tset.src_csets, mg_node) {
|
|
list_splice_tail_init(&cset->mg_tasks, &cset->tasks);
|
|
list_del_init(&cset->mg_node);
|
|
}
|
|
up_write(&css_set_rwsem);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
|
|
* @dst_cgrp: the cgroup to attach to
|
|
* @leader: the task or the leader of the threadgroup to be attached
|
|
* @threadgroup: attach the whole threadgroup?
|
|
*
|
|
* Call holding cgroup_mutex and cgroup_threadgroup_rwsem.
|
|
*/
|
|
static int cgroup_attach_task(struct cgroup *dst_cgrp,
|
|
struct task_struct *leader, bool threadgroup)
|
|
{
|
|
LIST_HEAD(preloaded_csets);
|
|
struct task_struct *task;
|
|
int ret;
|
|
|
|
/* look up all src csets */
|
|
down_read(&css_set_rwsem);
|
|
rcu_read_lock();
|
|
task = leader;
|
|
do {
|
|
cgroup_migrate_add_src(task_css_set(task), dst_cgrp,
|
|
&preloaded_csets);
|
|
if (!threadgroup)
|
|
break;
|
|
} while_each_thread(leader, task);
|
|
rcu_read_unlock();
|
|
up_read(&css_set_rwsem);
|
|
|
|
/* prepare dst csets and commit */
|
|
ret = cgroup_migrate_prepare_dst(dst_cgrp, &preloaded_csets);
|
|
if (!ret)
|
|
ret = cgroup_migrate(dst_cgrp, leader, threadgroup);
|
|
|
|
cgroup_migrate_finish(&preloaded_csets);
|
|
return ret;
|
|
}
|
|
|
|
static int cgroup_procs_write_permission(struct task_struct *task,
|
|
struct cgroup *dst_cgrp,
|
|
struct kernfs_open_file *of)
|
|
{
|
|
const struct cred *cred = current_cred();
|
|
const struct cred *tcred = get_task_cred(task);
|
|
int ret = 0;
|
|
|
|
/*
|
|
* even if we're attaching all tasks in the thread group, we only
|
|
* need to check permissions on one of them.
|
|
*/
|
|
if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
|
|
!uid_eq(cred->euid, tcred->uid) &&
|
|
!uid_eq(cred->euid, tcred->suid))
|
|
ret = -EACCES;
|
|
|
|
if (!ret && cgroup_on_dfl(dst_cgrp)) {
|
|
struct super_block *sb = of->file->f_path.dentry->d_sb;
|
|
struct cgroup *cgrp;
|
|
struct inode *inode;
|
|
|
|
down_read(&css_set_rwsem);
|
|
cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
|
|
up_read(&css_set_rwsem);
|
|
|
|
while (!cgroup_is_descendant(dst_cgrp, cgrp))
|
|
cgrp = cgroup_parent(cgrp);
|
|
|
|
ret = -ENOMEM;
|
|
inode = kernfs_get_inode(sb, cgrp->procs_file.kn);
|
|
if (inode) {
|
|
ret = inode_permission(inode, MAY_WRITE);
|
|
iput(inode);
|
|
}
|
|
}
|
|
|
|
put_cred(tcred);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Find the task_struct of the task to attach by vpid and pass it along to the
|
|
* function to attach either it or all tasks in its threadgroup. Will lock
|
|
* cgroup_mutex and threadgroup.
|
|
*/
|
|
static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
|
|
size_t nbytes, loff_t off, bool threadgroup)
|
|
{
|
|
struct task_struct *tsk;
|
|
struct cgroup *cgrp;
|
|
pid_t pid;
|
|
int ret;
|
|
|
|
if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
|
|
return -EINVAL;
|
|
|
|
cgrp = cgroup_kn_lock_live(of->kn);
|
|
if (!cgrp)
|
|
return -ENODEV;
|
|
|
|
percpu_down_write(&cgroup_threadgroup_rwsem);
|
|
rcu_read_lock();
|
|
if (pid) {
|
|
tsk = find_task_by_vpid(pid);
|
|
if (!tsk) {
|
|
ret = -ESRCH;
|
|
goto out_unlock_rcu;
|
|
}
|
|
} else {
|
|
tsk = current;
|
|
}
|
|
|
|
if (threadgroup)
|
|
tsk = tsk->group_leader;
|
|
|
|
/*
|
|
* Workqueue threads may acquire PF_NO_SETAFFINITY and become
|
|
* trapped in a cpuset, or RT worker may be born in a cgroup
|
|
* with no rt_runtime allocated. Just say no.
|
|
*/
|
|
if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) {
|
|
ret = -EINVAL;
|
|
goto out_unlock_rcu;
|
|
}
|
|
|
|
get_task_struct(tsk);
|
|
rcu_read_unlock();
|
|
|
|
ret = cgroup_procs_write_permission(tsk, cgrp, of);
|
|
if (!ret)
|
|
ret = cgroup_attach_task(cgrp, tsk, threadgroup);
|
|
|
|
put_task_struct(tsk);
|
|
goto out_unlock_threadgroup;
|
|
|
|
out_unlock_rcu:
|
|
rcu_read_unlock();
|
|
out_unlock_threadgroup:
|
|
percpu_up_write(&cgroup_threadgroup_rwsem);
|
|
cgroup_kn_unlock(of->kn);
|
|
return ret ?: nbytes;
|
|
}
|
|
|
|
/**
|
|
* cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
|
|
* @from: attach to all cgroups of a given task
|
|
* @tsk: the task to be attached
|
|
*/
|
|
int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
|
|
{
|
|
struct cgroup_root *root;
|
|
int retval = 0;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
for_each_root(root) {
|
|
struct cgroup *from_cgrp;
|
|
|
|
if (root == &cgrp_dfl_root)
|
|
continue;
|
|
|
|
down_read(&css_set_rwsem);
|
|
from_cgrp = task_cgroup_from_root(from, root);
|
|
up_read(&css_set_rwsem);
|
|
|
|
retval = cgroup_attach_task(from_cgrp, tsk, false);
|
|
if (retval)
|
|
break;
|
|
}
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
return retval;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
|
|
|
|
static ssize_t cgroup_tasks_write(struct kernfs_open_file *of,
|
|
char *buf, size_t nbytes, loff_t off)
|
|
{
|
|
return __cgroup_procs_write(of, buf, nbytes, off, false);
|
|
}
|
|
|
|
static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
|
|
char *buf, size_t nbytes, loff_t off)
|
|
{
|
|
return __cgroup_procs_write(of, buf, nbytes, off, true);
|
|
}
|
|
|
|
static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
|
|
char *buf, size_t nbytes, loff_t off)
|
|
{
|
|
struct cgroup *cgrp;
|
|
|
|
BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
|
|
|
|
cgrp = cgroup_kn_lock_live(of->kn);
|
|
if (!cgrp)
|
|
return -ENODEV;
|
|
spin_lock(&release_agent_path_lock);
|
|
strlcpy(cgrp->root->release_agent_path, strstrip(buf),
|
|
sizeof(cgrp->root->release_agent_path));
|
|
spin_unlock(&release_agent_path_lock);
|
|
cgroup_kn_unlock(of->kn);
|
|
return nbytes;
|
|
}
|
|
|
|
static int cgroup_release_agent_show(struct seq_file *seq, void *v)
|
|
{
|
|
struct cgroup *cgrp = seq_css(seq)->cgroup;
|
|
|
|
spin_lock(&release_agent_path_lock);
|
|
seq_puts(seq, cgrp->root->release_agent_path);
|
|
spin_unlock(&release_agent_path_lock);
|
|
seq_putc(seq, '\n');
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
|
|
{
|
|
seq_puts(seq, "0\n");
|
|
return 0;
|
|
}
|
|
|
|
static void cgroup_print_ss_mask(struct seq_file *seq, unsigned long ss_mask)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
bool printed = false;
|
|
int ssid;
|
|
|
|
for_each_subsys_which(ss, ssid, &ss_mask) {
|
|
if (printed)
|
|
seq_putc(seq, ' ');
|
|
seq_printf(seq, "%s", ss->name);
|
|
printed = true;
|
|
}
|
|
if (printed)
|
|
seq_putc(seq, '\n');
|
|
}
|
|
|
|
/* show controllers which are currently attached to the default hierarchy */
|
|
static int cgroup_root_controllers_show(struct seq_file *seq, void *v)
|
|
{
|
|
struct cgroup *cgrp = seq_css(seq)->cgroup;
|
|
|
|
cgroup_print_ss_mask(seq, cgrp->root->subsys_mask &
|
|
~cgrp_dfl_root_inhibit_ss_mask);
|
|
return 0;
|
|
}
|
|
|
|
/* show controllers which are enabled from the parent */
|
|
static int cgroup_controllers_show(struct seq_file *seq, void *v)
|
|
{
|
|
struct cgroup *cgrp = seq_css(seq)->cgroup;
|
|
|
|
cgroup_print_ss_mask(seq, cgroup_parent(cgrp)->subtree_control);
|
|
return 0;
|
|
}
|
|
|
|
/* show controllers which are enabled for a given cgroup's children */
|
|
static int cgroup_subtree_control_show(struct seq_file *seq, void *v)
|
|
{
|
|
struct cgroup *cgrp = seq_css(seq)->cgroup;
|
|
|
|
cgroup_print_ss_mask(seq, cgrp->subtree_control);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy
|
|
* @cgrp: root of the subtree to update csses for
|
|
*
|
|
* @cgrp's child_subsys_mask has changed and its subtree's (self excluded)
|
|
* css associations need to be updated accordingly. This function looks up
|
|
* all css_sets which are attached to the subtree, creates the matching
|
|
* updated css_sets and migrates the tasks to the new ones.
|
|
*/
|
|
static int cgroup_update_dfl_csses(struct cgroup *cgrp)
|
|
{
|
|
LIST_HEAD(preloaded_csets);
|
|
struct cgroup_subsys_state *css;
|
|
struct css_set *src_cset;
|
|
int ret;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
percpu_down_write(&cgroup_threadgroup_rwsem);
|
|
|
|
/* look up all csses currently attached to @cgrp's subtree */
|
|
down_read(&css_set_rwsem);
|
|
css_for_each_descendant_pre(css, cgroup_css(cgrp, NULL)) {
|
|
struct cgrp_cset_link *link;
|
|
|
|
/* self is not affected by child_subsys_mask change */
|
|
if (css->cgroup == cgrp)
|
|
continue;
|
|
|
|
list_for_each_entry(link, &css->cgroup->cset_links, cset_link)
|
|
cgroup_migrate_add_src(link->cset, cgrp,
|
|
&preloaded_csets);
|
|
}
|
|
up_read(&css_set_rwsem);
|
|
|
|
/* NULL dst indicates self on default hierarchy */
|
|
ret = cgroup_migrate_prepare_dst(NULL, &preloaded_csets);
|
|
if (ret)
|
|
goto out_finish;
|
|
|
|
list_for_each_entry(src_cset, &preloaded_csets, mg_preload_node) {
|
|
struct task_struct *last_task = NULL, *task;
|
|
|
|
/* src_csets precede dst_csets, break on the first dst_cset */
|
|
if (!src_cset->mg_src_cgrp)
|
|
break;
|
|
|
|
/*
|
|
* All tasks in src_cset need to be migrated to the
|
|
* matching dst_cset. Empty it process by process. We
|
|
* walk tasks but migrate processes. The leader might even
|
|
* belong to a different cset but such src_cset would also
|
|
* be among the target src_csets because the default
|
|
* hierarchy enforces per-process membership.
|
|
*/
|
|
while (true) {
|
|
down_read(&css_set_rwsem);
|
|
task = list_first_entry_or_null(&src_cset->tasks,
|
|
struct task_struct, cg_list);
|
|
if (task) {
|
|
task = task->group_leader;
|
|
WARN_ON_ONCE(!task_css_set(task)->mg_src_cgrp);
|
|
get_task_struct(task);
|
|
}
|
|
up_read(&css_set_rwsem);
|
|
|
|
if (!task)
|
|
break;
|
|
|
|
/* guard against possible infinite loop */
|
|
if (WARN(last_task == task,
|
|
"cgroup: update_dfl_csses failed to make progress, aborting in inconsistent state\n"))
|
|
goto out_finish;
|
|
last_task = task;
|
|
|
|
ret = cgroup_migrate(src_cset->dfl_cgrp, task, true);
|
|
|
|
put_task_struct(task);
|
|
|
|
if (WARN(ret, "cgroup: failed to update controllers for the default hierarchy (%d), further operations may crash or hang\n", ret))
|
|
goto out_finish;
|
|
}
|
|
}
|
|
|
|
out_finish:
|
|
cgroup_migrate_finish(&preloaded_csets);
|
|
percpu_up_write(&cgroup_threadgroup_rwsem);
|
|
return ret;
|
|
}
|
|
|
|
/* change the enabled child controllers for a cgroup in the default hierarchy */
|
|
static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
|
|
char *buf, size_t nbytes,
|
|
loff_t off)
|
|
{
|
|
unsigned long enable = 0, disable = 0;
|
|
unsigned long css_enable, css_disable, old_sc, new_sc, old_ss, new_ss;
|
|
struct cgroup *cgrp, *child;
|
|
struct cgroup_subsys *ss;
|
|
char *tok;
|
|
int ssid, ret;
|
|
|
|
/*
|
|
* Parse input - space separated list of subsystem names prefixed
|
|
* with either + or -.
|
|
*/
|
|
buf = strstrip(buf);
|
|
while ((tok = strsep(&buf, " "))) {
|
|
unsigned long tmp_ss_mask = ~cgrp_dfl_root_inhibit_ss_mask;
|
|
|
|
if (tok[0] == '\0')
|
|
continue;
|
|
for_each_subsys_which(ss, ssid, &tmp_ss_mask) {
|
|
if (!cgroup_ssid_enabled(ssid) ||
|
|
strcmp(tok + 1, ss->name))
|
|
continue;
|
|
|
|
if (*tok == '+') {
|
|
enable |= 1 << ssid;
|
|
disable &= ~(1 << ssid);
|
|
} else if (*tok == '-') {
|
|
disable |= 1 << ssid;
|
|
enable &= ~(1 << ssid);
|
|
} else {
|
|
return -EINVAL;
|
|
}
|
|
break;
|
|
}
|
|
if (ssid == CGROUP_SUBSYS_COUNT)
|
|
return -EINVAL;
|
|
}
|
|
|
|
cgrp = cgroup_kn_lock_live(of->kn);
|
|
if (!cgrp)
|
|
return -ENODEV;
|
|
|
|
for_each_subsys(ss, ssid) {
|
|
if (enable & (1 << ssid)) {
|
|
if (cgrp->subtree_control & (1 << ssid)) {
|
|
enable &= ~(1 << ssid);
|
|
continue;
|
|
}
|
|
|
|
/* unavailable or not enabled on the parent? */
|
|
if (!(cgrp_dfl_root.subsys_mask & (1 << ssid)) ||
|
|
(cgroup_parent(cgrp) &&
|
|
!(cgroup_parent(cgrp)->subtree_control & (1 << ssid)))) {
|
|
ret = -ENOENT;
|
|
goto out_unlock;
|
|
}
|
|
} else if (disable & (1 << ssid)) {
|
|
if (!(cgrp->subtree_control & (1 << ssid))) {
|
|
disable &= ~(1 << ssid);
|
|
continue;
|
|
}
|
|
|
|
/* a child has it enabled? */
|
|
cgroup_for_each_live_child(child, cgrp) {
|
|
if (child->subtree_control & (1 << ssid)) {
|
|
ret = -EBUSY;
|
|
goto out_unlock;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!enable && !disable) {
|
|
ret = 0;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/*
|
|
* Except for the root, subtree_control must be zero for a cgroup
|
|
* with tasks so that child cgroups don't compete against tasks.
|
|
*/
|
|
if (enable && cgroup_parent(cgrp) && !list_empty(&cgrp->cset_links)) {
|
|
ret = -EBUSY;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/*
|
|
* Update subsys masks and calculate what needs to be done. More
|
|
* subsystems than specified may need to be enabled or disabled
|
|
* depending on subsystem dependencies.
|
|
*/
|
|
old_sc = cgrp->subtree_control;
|
|
old_ss = cgrp->child_subsys_mask;
|
|
new_sc = (old_sc | enable) & ~disable;
|
|
new_ss = cgroup_calc_child_subsys_mask(cgrp, new_sc);
|
|
|
|
css_enable = ~old_ss & new_ss;
|
|
css_disable = old_ss & ~new_ss;
|
|
enable |= css_enable;
|
|
disable |= css_disable;
|
|
|
|
/*
|
|
* Because css offlining is asynchronous, userland might try to
|
|
* re-enable the same controller while the previous instance is
|
|
* still around. In such cases, wait till it's gone using
|
|
* offline_waitq.
|
|
*/
|
|
for_each_subsys_which(ss, ssid, &css_enable) {
|
|
cgroup_for_each_live_child(child, cgrp) {
|
|
DEFINE_WAIT(wait);
|
|
|
|
if (!cgroup_css(child, ss))
|
|
continue;
|
|
|
|
cgroup_get(child);
|
|
prepare_to_wait(&child->offline_waitq, &wait,
|
|
TASK_UNINTERRUPTIBLE);
|
|
cgroup_kn_unlock(of->kn);
|
|
schedule();
|
|
finish_wait(&child->offline_waitq, &wait);
|
|
cgroup_put(child);
|
|
|
|
return restart_syscall();
|
|
}
|
|
}
|
|
|
|
cgrp->subtree_control = new_sc;
|
|
cgrp->child_subsys_mask = new_ss;
|
|
|
|
/*
|
|
* Create new csses or make the existing ones visible. A css is
|
|
* created invisible if it's being implicitly enabled through
|
|
* dependency. An invisible css is made visible when the userland
|
|
* explicitly enables it.
|
|
*/
|
|
for_each_subsys(ss, ssid) {
|
|
if (!(enable & (1 << ssid)))
|
|
continue;
|
|
|
|
cgroup_for_each_live_child(child, cgrp) {
|
|
if (css_enable & (1 << ssid))
|
|
ret = create_css(child, ss,
|
|
cgrp->subtree_control & (1 << ssid));
|
|
else
|
|
ret = css_populate_dir(cgroup_css(child, ss),
|
|
NULL);
|
|
if (ret)
|
|
goto err_undo_css;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* At this point, cgroup_e_css() results reflect the new csses
|
|
* making the following cgroup_update_dfl_csses() properly update
|
|
* css associations of all tasks in the subtree.
|
|
*/
|
|
ret = cgroup_update_dfl_csses(cgrp);
|
|
if (ret)
|
|
goto err_undo_css;
|
|
|
|
/*
|
|
* All tasks are migrated out of disabled csses. Kill or hide
|
|
* them. A css is hidden when the userland requests it to be
|
|
* disabled while other subsystems are still depending on it. The
|
|
* css must not actively control resources and be in the vanilla
|
|
* state if it's made visible again later. Controllers which may
|
|
* be depended upon should provide ->css_reset() for this purpose.
|
|
*/
|
|
for_each_subsys(ss, ssid) {
|
|
if (!(disable & (1 << ssid)))
|
|
continue;
|
|
|
|
cgroup_for_each_live_child(child, cgrp) {
|
|
struct cgroup_subsys_state *css = cgroup_css(child, ss);
|
|
|
|
if (css_disable & (1 << ssid)) {
|
|
kill_css(css);
|
|
} else {
|
|
css_clear_dir(css, NULL);
|
|
if (ss->css_reset)
|
|
ss->css_reset(css);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The effective csses of all the descendants (excluding @cgrp) may
|
|
* have changed. Subsystems can optionally subscribe to this event
|
|
* by implementing ->css_e_css_changed() which is invoked if any of
|
|
* the effective csses seen from the css's cgroup may have changed.
|
|
*/
|
|
for_each_subsys(ss, ssid) {
|
|
struct cgroup_subsys_state *this_css = cgroup_css(cgrp, ss);
|
|
struct cgroup_subsys_state *css;
|
|
|
|
if (!ss->css_e_css_changed || !this_css)
|
|
continue;
|
|
|
|
css_for_each_descendant_pre(css, this_css)
|
|
if (css != this_css)
|
|
ss->css_e_css_changed(css);
|
|
}
|
|
|
|
kernfs_activate(cgrp->kn);
|
|
ret = 0;
|
|
out_unlock:
|
|
cgroup_kn_unlock(of->kn);
|
|
return ret ?: nbytes;
|
|
|
|
err_undo_css:
|
|
cgrp->subtree_control = old_sc;
|
|
cgrp->child_subsys_mask = old_ss;
|
|
|
|
for_each_subsys(ss, ssid) {
|
|
if (!(enable & (1 << ssid)))
|
|
continue;
|
|
|
|
cgroup_for_each_live_child(child, cgrp) {
|
|
struct cgroup_subsys_state *css = cgroup_css(child, ss);
|
|
|
|
if (!css)
|
|
continue;
|
|
|
|
if (css_enable & (1 << ssid))
|
|
kill_css(css);
|
|
else
|
|
css_clear_dir(css, NULL);
|
|
}
|
|
}
|
|
goto out_unlock;
|
|
}
|
|
|
|
static int cgroup_events_show(struct seq_file *seq, void *v)
|
|
{
|
|
seq_printf(seq, "populated %d\n",
|
|
(bool)seq_css(seq)->cgroup->populated_cnt);
|
|
return 0;
|
|
}
|
|
|
|
static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf,
|
|
size_t nbytes, loff_t off)
|
|
{
|
|
struct cgroup *cgrp = of->kn->parent->priv;
|
|
struct cftype *cft = of->kn->priv;
|
|
struct cgroup_subsys_state *css;
|
|
int ret;
|
|
|
|
if (cft->write)
|
|
return cft->write(of, buf, nbytes, off);
|
|
|
|
/*
|
|
* kernfs guarantees that a file isn't deleted with operations in
|
|
* flight, which means that the matching css is and stays alive and
|
|
* doesn't need to be pinned. The RCU locking is not necessary
|
|
* either. It's just for the convenience of using cgroup_css().
|
|
*/
|
|
rcu_read_lock();
|
|
css = cgroup_css(cgrp, cft->ss);
|
|
rcu_read_unlock();
|
|
|
|
if (cft->write_u64) {
|
|
unsigned long long v;
|
|
ret = kstrtoull(buf, 0, &v);
|
|
if (!ret)
|
|
ret = cft->write_u64(css, cft, v);
|
|
} else if (cft->write_s64) {
|
|
long long v;
|
|
ret = kstrtoll(buf, 0, &v);
|
|
if (!ret)
|
|
ret = cft->write_s64(css, cft, v);
|
|
} else {
|
|
ret = -EINVAL;
|
|
}
|
|
|
|
return ret ?: nbytes;
|
|
}
|
|
|
|
static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos)
|
|
{
|
|
return seq_cft(seq)->seq_start(seq, ppos);
|
|
}
|
|
|
|
static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos)
|
|
{
|
|
return seq_cft(seq)->seq_next(seq, v, ppos);
|
|
}
|
|
|
|
static void cgroup_seqfile_stop(struct seq_file *seq, void *v)
|
|
{
|
|
seq_cft(seq)->seq_stop(seq, v);
|
|
}
|
|
|
|
static int cgroup_seqfile_show(struct seq_file *m, void *arg)
|
|
{
|
|
struct cftype *cft = seq_cft(m);
|
|
struct cgroup_subsys_state *css = seq_css(m);
|
|
|
|
if (cft->seq_show)
|
|
return cft->seq_show(m, arg);
|
|
|
|
if (cft->read_u64)
|
|
seq_printf(m, "%llu\n", cft->read_u64(css, cft));
|
|
else if (cft->read_s64)
|
|
seq_printf(m, "%lld\n", cft->read_s64(css, cft));
|
|
else
|
|
return -EINVAL;
|
|
return 0;
|
|
}
|
|
|
|
static struct kernfs_ops cgroup_kf_single_ops = {
|
|
.atomic_write_len = PAGE_SIZE,
|
|
.write = cgroup_file_write,
|
|
.seq_show = cgroup_seqfile_show,
|
|
};
|
|
|
|
static struct kernfs_ops cgroup_kf_ops = {
|
|
.atomic_write_len = PAGE_SIZE,
|
|
.write = cgroup_file_write,
|
|
.seq_start = cgroup_seqfile_start,
|
|
.seq_next = cgroup_seqfile_next,
|
|
.seq_stop = cgroup_seqfile_stop,
|
|
.seq_show = cgroup_seqfile_show,
|
|
};
|
|
|
|
/*
|
|
* cgroup_rename - Only allow simple rename of directories in place.
|
|
*/
|
|
static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
|
|
const char *new_name_str)
|
|
{
|
|
struct cgroup *cgrp = kn->priv;
|
|
int ret;
|
|
|
|
if (kernfs_type(kn) != KERNFS_DIR)
|
|
return -ENOTDIR;
|
|
if (kn->parent != new_parent)
|
|
return -EIO;
|
|
|
|
/*
|
|
* This isn't a proper migration and its usefulness is very
|
|
* limited. Disallow on the default hierarchy.
|
|
*/
|
|
if (cgroup_on_dfl(cgrp))
|
|
return -EPERM;
|
|
|
|
/*
|
|
* We're gonna grab cgroup_mutex which nests outside kernfs
|
|
* active_ref. kernfs_rename() doesn't require active_ref
|
|
* protection. Break them before grabbing cgroup_mutex.
|
|
*/
|
|
kernfs_break_active_protection(new_parent);
|
|
kernfs_break_active_protection(kn);
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
ret = kernfs_rename(kn, new_parent, new_name_str);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
kernfs_unbreak_active_protection(kn);
|
|
kernfs_unbreak_active_protection(new_parent);
|
|
return ret;
|
|
}
|
|
|
|
/* set uid and gid of cgroup dirs and files to that of the creator */
|
|
static int cgroup_kn_set_ugid(struct kernfs_node *kn)
|
|
{
|
|
struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID,
|
|
.ia_uid = current_fsuid(),
|
|
.ia_gid = current_fsgid(), };
|
|
|
|
if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) &&
|
|
gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID))
|
|
return 0;
|
|
|
|
return kernfs_setattr(kn, &iattr);
|
|
}
|
|
|
|
static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
|
|
struct cftype *cft)
|
|
{
|
|
char name[CGROUP_FILE_NAME_MAX];
|
|
struct kernfs_node *kn;
|
|
struct lock_class_key *key = NULL;
|
|
int ret;
|
|
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
key = &cft->lockdep_key;
|
|
#endif
|
|
kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name),
|
|
cgroup_file_mode(cft), 0, cft->kf_ops, cft,
|
|
NULL, key);
|
|
if (IS_ERR(kn))
|
|
return PTR_ERR(kn);
|
|
|
|
ret = cgroup_kn_set_ugid(kn);
|
|
if (ret) {
|
|
kernfs_remove(kn);
|
|
return ret;
|
|
}
|
|
|
|
if (cft->file_offset) {
|
|
struct cgroup_file *cfile = (void *)css + cft->file_offset;
|
|
|
|
kernfs_get(kn);
|
|
cfile->kn = kn;
|
|
list_add(&cfile->node, &css->files);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroup_addrm_files - add or remove files to a cgroup directory
|
|
* @css: the target css
|
|
* @cgrp: the target cgroup (usually css->cgroup)
|
|
* @cfts: array of cftypes to be added
|
|
* @is_add: whether to add or remove
|
|
*
|
|
* Depending on @is_add, add or remove files defined by @cfts on @cgrp.
|
|
* For removals, this function never fails.
|
|
*/
|
|
static int cgroup_addrm_files(struct cgroup_subsys_state *css,
|
|
struct cgroup *cgrp, struct cftype cfts[],
|
|
bool is_add)
|
|
{
|
|
struct cftype *cft, *cft_end = NULL;
|
|
int ret;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
restart:
|
|
for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) {
|
|
/* does cft->flags tell us to skip this file on @cgrp? */
|
|
if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
|
|
continue;
|
|
if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp))
|
|
continue;
|
|
if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp))
|
|
continue;
|
|
if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp))
|
|
continue;
|
|
|
|
if (is_add) {
|
|
ret = cgroup_add_file(css, cgrp, cft);
|
|
if (ret) {
|
|
pr_warn("%s: failed to add %s, err=%d\n",
|
|
__func__, cft->name, ret);
|
|
cft_end = cft;
|
|
is_add = false;
|
|
goto restart;
|
|
}
|
|
} else {
|
|
cgroup_rm_file(cgrp, cft);
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add)
|
|
{
|
|
LIST_HEAD(pending);
|
|
struct cgroup_subsys *ss = cfts[0].ss;
|
|
struct cgroup *root = &ss->root->cgrp;
|
|
struct cgroup_subsys_state *css;
|
|
int ret = 0;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
/* add/rm files for all cgroups created before */
|
|
css_for_each_descendant_pre(css, cgroup_css(root, ss)) {
|
|
struct cgroup *cgrp = css->cgroup;
|
|
|
|
if (cgroup_is_dead(cgrp))
|
|
continue;
|
|
|
|
ret = cgroup_addrm_files(css, cgrp, cfts, is_add);
|
|
if (ret)
|
|
break;
|
|
}
|
|
|
|
if (is_add && !ret)
|
|
kernfs_activate(root->kn);
|
|
return ret;
|
|
}
|
|
|
|
static void cgroup_exit_cftypes(struct cftype *cfts)
|
|
{
|
|
struct cftype *cft;
|
|
|
|
for (cft = cfts; cft->name[0] != '\0'; cft++) {
|
|
/* free copy for custom atomic_write_len, see init_cftypes() */
|
|
if (cft->max_write_len && cft->max_write_len != PAGE_SIZE)
|
|
kfree(cft->kf_ops);
|
|
cft->kf_ops = NULL;
|
|
cft->ss = NULL;
|
|
|
|
/* revert flags set by cgroup core while adding @cfts */
|
|
cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL);
|
|
}
|
|
}
|
|
|
|
static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
|
|
{
|
|
struct cftype *cft;
|
|
|
|
for (cft = cfts; cft->name[0] != '\0'; cft++) {
|
|
struct kernfs_ops *kf_ops;
|
|
|
|
WARN_ON(cft->ss || cft->kf_ops);
|
|
|
|
if (cft->seq_start)
|
|
kf_ops = &cgroup_kf_ops;
|
|
else
|
|
kf_ops = &cgroup_kf_single_ops;
|
|
|
|
/*
|
|
* Ugh... if @cft wants a custom max_write_len, we need to
|
|
* make a copy of kf_ops to set its atomic_write_len.
|
|
*/
|
|
if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) {
|
|
kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL);
|
|
if (!kf_ops) {
|
|
cgroup_exit_cftypes(cfts);
|
|
return -ENOMEM;
|
|
}
|
|
kf_ops->atomic_write_len = cft->max_write_len;
|
|
}
|
|
|
|
cft->kf_ops = kf_ops;
|
|
cft->ss = ss;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_rm_cftypes_locked(struct cftype *cfts)
|
|
{
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
if (!cfts || !cfts[0].ss)
|
|
return -ENOENT;
|
|
|
|
list_del(&cfts->node);
|
|
cgroup_apply_cftypes(cfts, false);
|
|
cgroup_exit_cftypes(cfts);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroup_rm_cftypes - remove an array of cftypes from a subsystem
|
|
* @cfts: zero-length name terminated array of cftypes
|
|
*
|
|
* Unregister @cfts. Files described by @cfts are removed from all
|
|
* existing cgroups and all future cgroups won't have them either. This
|
|
* function can be called anytime whether @cfts' subsys is attached or not.
|
|
*
|
|
* Returns 0 on successful unregistration, -ENOENT if @cfts is not
|
|
* registered.
|
|
*/
|
|
int cgroup_rm_cftypes(struct cftype *cfts)
|
|
{
|
|
int ret;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
ret = cgroup_rm_cftypes_locked(cfts);
|
|
mutex_unlock(&cgroup_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* cgroup_add_cftypes - add an array of cftypes to a subsystem
|
|
* @ss: target cgroup subsystem
|
|
* @cfts: zero-length name terminated array of cftypes
|
|
*
|
|
* Register @cfts to @ss. Files described by @cfts are created for all
|
|
* existing cgroups to which @ss is attached and all future cgroups will
|
|
* have them too. This function can be called anytime whether @ss is
|
|
* attached or not.
|
|
*
|
|
* Returns 0 on successful registration, -errno on failure. Note that this
|
|
* function currently returns 0 as long as @cfts registration is successful
|
|
* even if some file creation attempts on existing cgroups fail.
|
|
*/
|
|
static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
|
|
{
|
|
int ret;
|
|
|
|
if (!cgroup_ssid_enabled(ss->id))
|
|
return 0;
|
|
|
|
if (!cfts || cfts[0].name[0] == '\0')
|
|
return 0;
|
|
|
|
ret = cgroup_init_cftypes(ss, cfts);
|
|
if (ret)
|
|
return ret;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
list_add_tail(&cfts->node, &ss->cfts);
|
|
ret = cgroup_apply_cftypes(cfts, true);
|
|
if (ret)
|
|
cgroup_rm_cftypes_locked(cfts);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy
|
|
* @ss: target cgroup subsystem
|
|
* @cfts: zero-length name terminated array of cftypes
|
|
*
|
|
* Similar to cgroup_add_cftypes() but the added files are only used for
|
|
* the default hierarchy.
|
|
*/
|
|
int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
|
|
{
|
|
struct cftype *cft;
|
|
|
|
for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
|
|
cft->flags |= __CFTYPE_ONLY_ON_DFL;
|
|
return cgroup_add_cftypes(ss, cfts);
|
|
}
|
|
|
|
/**
|
|
* cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies
|
|
* @ss: target cgroup subsystem
|
|
* @cfts: zero-length name terminated array of cftypes
|
|
*
|
|
* Similar to cgroup_add_cftypes() but the added files are only used for
|
|
* the legacy hierarchies.
|
|
*/
|
|
int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
|
|
{
|
|
struct cftype *cft;
|
|
|
|
/*
|
|
* If legacy_flies_on_dfl, we want to show the legacy files on the
|
|
* dfl hierarchy but iff the target subsystem hasn't been updated
|
|
* for the dfl hierarchy yet.
|
|
*/
|
|
if (!cgroup_legacy_files_on_dfl ||
|
|
ss->dfl_cftypes != ss->legacy_cftypes) {
|
|
for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
|
|
cft->flags |= __CFTYPE_NOT_ON_DFL;
|
|
}
|
|
|
|
return cgroup_add_cftypes(ss, cfts);
|
|
}
|
|
|
|
/**
|
|
* cgroup_task_count - count the number of tasks in a cgroup.
|
|
* @cgrp: the cgroup in question
|
|
*
|
|
* Return the number of tasks in the cgroup.
|
|
*/
|
|
static int cgroup_task_count(const struct cgroup *cgrp)
|
|
{
|
|
int count = 0;
|
|
struct cgrp_cset_link *link;
|
|
|
|
down_read(&css_set_rwsem);
|
|
list_for_each_entry(link, &cgrp->cset_links, cset_link)
|
|
count += atomic_read(&link->cset->refcount);
|
|
up_read(&css_set_rwsem);
|
|
return count;
|
|
}
|
|
|
|
/**
|
|
* css_next_child - find the next child of a given css
|
|
* @pos: the current position (%NULL to initiate traversal)
|
|
* @parent: css whose children to walk
|
|
*
|
|
* This function returns the next child of @parent and should be called
|
|
* under either cgroup_mutex or RCU read lock. The only requirement is
|
|
* that @parent and @pos are accessible. The next sibling is guaranteed to
|
|
* be returned regardless of their states.
|
|
*
|
|
* If a subsystem synchronizes ->css_online() and the start of iteration, a
|
|
* css which finished ->css_online() is guaranteed to be visible in the
|
|
* future iterations and will stay visible until the last reference is put.
|
|
* A css which hasn't finished ->css_online() or already finished
|
|
* ->css_offline() may show up during traversal. It's each subsystem's
|
|
* responsibility to synchronize against on/offlining.
|
|
*/
|
|
struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
|
|
struct cgroup_subsys_state *parent)
|
|
{
|
|
struct cgroup_subsys_state *next;
|
|
|
|
cgroup_assert_mutex_or_rcu_locked();
|
|
|
|
/*
|
|
* @pos could already have been unlinked from the sibling list.
|
|
* Once a cgroup is removed, its ->sibling.next is no longer
|
|
* updated when its next sibling changes. CSS_RELEASED is set when
|
|
* @pos is taken off list, at which time its next pointer is valid,
|
|
* and, as releases are serialized, the one pointed to by the next
|
|
* pointer is guaranteed to not have started release yet. This
|
|
* implies that if we observe !CSS_RELEASED on @pos in this RCU
|
|
* critical section, the one pointed to by its next pointer is
|
|
* guaranteed to not have finished its RCU grace period even if we
|
|
* have dropped rcu_read_lock() inbetween iterations.
|
|
*
|
|
* If @pos has CSS_RELEASED set, its next pointer can't be
|
|
* dereferenced; however, as each css is given a monotonically
|
|
* increasing unique serial number and always appended to the
|
|
* sibling list, the next one can be found by walking the parent's
|
|
* children until the first css with higher serial number than
|
|
* @pos's. While this path can be slower, it happens iff iteration
|
|
* races against release and the race window is very small.
|
|
*/
|
|
if (!pos) {
|
|
next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling);
|
|
} else if (likely(!(pos->flags & CSS_RELEASED))) {
|
|
next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling);
|
|
} else {
|
|
list_for_each_entry_rcu(next, &parent->children, sibling)
|
|
if (next->serial_nr > pos->serial_nr)
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* @next, if not pointing to the head, can be dereferenced and is
|
|
* the next sibling.
|
|
*/
|
|
if (&next->sibling != &parent->children)
|
|
return next;
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* css_next_descendant_pre - find the next descendant for pre-order walk
|
|
* @pos: the current position (%NULL to initiate traversal)
|
|
* @root: css whose descendants to walk
|
|
*
|
|
* To be used by css_for_each_descendant_pre(). Find the next descendant
|
|
* to visit for pre-order traversal of @root's descendants. @root is
|
|
* included in the iteration and the first node to be visited.
|
|
*
|
|
* While this function requires cgroup_mutex or RCU read locking, it
|
|
* doesn't require the whole traversal to be contained in a single critical
|
|
* section. This function will return the correct next descendant as long
|
|
* as both @pos and @root are accessible and @pos is a descendant of @root.
|
|
*
|
|
* If a subsystem synchronizes ->css_online() and the start of iteration, a
|
|
* css which finished ->css_online() is guaranteed to be visible in the
|
|
* future iterations and will stay visible until the last reference is put.
|
|
* A css which hasn't finished ->css_online() or already finished
|
|
* ->css_offline() may show up during traversal. It's each subsystem's
|
|
* responsibility to synchronize against on/offlining.
|
|
*/
|
|
struct cgroup_subsys_state *
|
|
css_next_descendant_pre(struct cgroup_subsys_state *pos,
|
|
struct cgroup_subsys_state *root)
|
|
{
|
|
struct cgroup_subsys_state *next;
|
|
|
|
cgroup_assert_mutex_or_rcu_locked();
|
|
|
|
/* if first iteration, visit @root */
|
|
if (!pos)
|
|
return root;
|
|
|
|
/* visit the first child if exists */
|
|
next = css_next_child(NULL, pos);
|
|
if (next)
|
|
return next;
|
|
|
|
/* no child, visit my or the closest ancestor's next sibling */
|
|
while (pos != root) {
|
|
next = css_next_child(pos, pos->parent);
|
|
if (next)
|
|
return next;
|
|
pos = pos->parent;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* css_rightmost_descendant - return the rightmost descendant of a css
|
|
* @pos: css of interest
|
|
*
|
|
* Return the rightmost descendant of @pos. If there's no descendant, @pos
|
|
* is returned. This can be used during pre-order traversal to skip
|
|
* subtree of @pos.
|
|
*
|
|
* While this function requires cgroup_mutex or RCU read locking, it
|
|
* doesn't require the whole traversal to be contained in a single critical
|
|
* section. This function will return the correct rightmost descendant as
|
|
* long as @pos is accessible.
|
|
*/
|
|
struct cgroup_subsys_state *
|
|
css_rightmost_descendant(struct cgroup_subsys_state *pos)
|
|
{
|
|
struct cgroup_subsys_state *last, *tmp;
|
|
|
|
cgroup_assert_mutex_or_rcu_locked();
|
|
|
|
do {
|
|
last = pos;
|
|
/* ->prev isn't RCU safe, walk ->next till the end */
|
|
pos = NULL;
|
|
css_for_each_child(tmp, last)
|
|
pos = tmp;
|
|
} while (pos);
|
|
|
|
return last;
|
|
}
|
|
|
|
static struct cgroup_subsys_state *
|
|
css_leftmost_descendant(struct cgroup_subsys_state *pos)
|
|
{
|
|
struct cgroup_subsys_state *last;
|
|
|
|
do {
|
|
last = pos;
|
|
pos = css_next_child(NULL, pos);
|
|
} while (pos);
|
|
|
|
return last;
|
|
}
|
|
|
|
/**
|
|
* css_next_descendant_post - find the next descendant for post-order walk
|
|
* @pos: the current position (%NULL to initiate traversal)
|
|
* @root: css whose descendants to walk
|
|
*
|
|
* To be used by css_for_each_descendant_post(). Find the next descendant
|
|
* to visit for post-order traversal of @root's descendants. @root is
|
|
* included in the iteration and the last node to be visited.
|
|
*
|
|
* While this function requires cgroup_mutex or RCU read locking, it
|
|
* doesn't require the whole traversal to be contained in a single critical
|
|
* section. This function will return the correct next descendant as long
|
|
* as both @pos and @cgroup are accessible and @pos is a descendant of
|
|
* @cgroup.
|
|
*
|
|
* If a subsystem synchronizes ->css_online() and the start of iteration, a
|
|
* css which finished ->css_online() is guaranteed to be visible in the
|
|
* future iterations and will stay visible until the last reference is put.
|
|
* A css which hasn't finished ->css_online() or already finished
|
|
* ->css_offline() may show up during traversal. It's each subsystem's
|
|
* responsibility to synchronize against on/offlining.
|
|
*/
|
|
struct cgroup_subsys_state *
|
|
css_next_descendant_post(struct cgroup_subsys_state *pos,
|
|
struct cgroup_subsys_state *root)
|
|
{
|
|
struct cgroup_subsys_state *next;
|
|
|
|
cgroup_assert_mutex_or_rcu_locked();
|
|
|
|
/* if first iteration, visit leftmost descendant which may be @root */
|
|
if (!pos)
|
|
return css_leftmost_descendant(root);
|
|
|
|
/* if we visited @root, we're done */
|
|
if (pos == root)
|
|
return NULL;
|
|
|
|
/* if there's an unvisited sibling, visit its leftmost descendant */
|
|
next = css_next_child(pos, pos->parent);
|
|
if (next)
|
|
return css_leftmost_descendant(next);
|
|
|
|
/* no sibling left, visit parent */
|
|
return pos->parent;
|
|
}
|
|
|
|
/**
|
|
* css_has_online_children - does a css have online children
|
|
* @css: the target css
|
|
*
|
|
* Returns %true if @css has any online children; otherwise, %false. This
|
|
* function can be called from any context but the caller is responsible
|
|
* for synchronizing against on/offlining as necessary.
|
|
*/
|
|
bool css_has_online_children(struct cgroup_subsys_state *css)
|
|
{
|
|
struct cgroup_subsys_state *child;
|
|
bool ret = false;
|
|
|
|
rcu_read_lock();
|
|
css_for_each_child(child, css) {
|
|
if (child->flags & CSS_ONLINE) {
|
|
ret = true;
|
|
break;
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* css_advance_task_iter - advance a task itererator to the next css_set
|
|
* @it: the iterator to advance
|
|
*
|
|
* Advance @it to the next css_set to walk.
|
|
*/
|
|
static void css_advance_task_iter(struct css_task_iter *it)
|
|
{
|
|
struct list_head *l = it->cset_pos;
|
|
struct cgrp_cset_link *link;
|
|
struct css_set *cset;
|
|
|
|
/* Advance to the next non-empty css_set */
|
|
do {
|
|
l = l->next;
|
|
if (l == it->cset_head) {
|
|
it->cset_pos = NULL;
|
|
return;
|
|
}
|
|
|
|
if (it->ss) {
|
|
cset = container_of(l, struct css_set,
|
|
e_cset_node[it->ss->id]);
|
|
} else {
|
|
link = list_entry(l, struct cgrp_cset_link, cset_link);
|
|
cset = link->cset;
|
|
}
|
|
} while (list_empty(&cset->tasks) && list_empty(&cset->mg_tasks));
|
|
|
|
it->cset_pos = l;
|
|
|
|
if (!list_empty(&cset->tasks))
|
|
it->task_pos = cset->tasks.next;
|
|
else
|
|
it->task_pos = cset->mg_tasks.next;
|
|
|
|
it->tasks_head = &cset->tasks;
|
|
it->mg_tasks_head = &cset->mg_tasks;
|
|
}
|
|
|
|
/**
|
|
* css_task_iter_start - initiate task iteration
|
|
* @css: the css to walk tasks of
|
|
* @it: the task iterator to use
|
|
*
|
|
* Initiate iteration through the tasks of @css. The caller can call
|
|
* css_task_iter_next() to walk through the tasks until the function
|
|
* returns NULL. On completion of iteration, css_task_iter_end() must be
|
|
* called.
|
|
*
|
|
* Note that this function acquires a lock which is released when the
|
|
* iteration finishes. The caller can't sleep while iteration is in
|
|
* progress.
|
|
*/
|
|
void css_task_iter_start(struct cgroup_subsys_state *css,
|
|
struct css_task_iter *it)
|
|
__acquires(css_set_rwsem)
|
|
{
|
|
/* no one should try to iterate before mounting cgroups */
|
|
WARN_ON_ONCE(!use_task_css_set_links);
|
|
|
|
down_read(&css_set_rwsem);
|
|
|
|
it->ss = css->ss;
|
|
|
|
if (it->ss)
|
|
it->cset_pos = &css->cgroup->e_csets[css->ss->id];
|
|
else
|
|
it->cset_pos = &css->cgroup->cset_links;
|
|
|
|
it->cset_head = it->cset_pos;
|
|
|
|
css_advance_task_iter(it);
|
|
}
|
|
|
|
/**
|
|
* css_task_iter_next - return the next task for the iterator
|
|
* @it: the task iterator being iterated
|
|
*
|
|
* The "next" function for task iteration. @it should have been
|
|
* initialized via css_task_iter_start(). Returns NULL when the iteration
|
|
* reaches the end.
|
|
*/
|
|
struct task_struct *css_task_iter_next(struct css_task_iter *it)
|
|
{
|
|
struct task_struct *res;
|
|
struct list_head *l = it->task_pos;
|
|
|
|
/* If the iterator cg is NULL, we have no tasks */
|
|
if (!it->cset_pos)
|
|
return NULL;
|
|
res = list_entry(l, struct task_struct, cg_list);
|
|
|
|
/*
|
|
* Advance iterator to find next entry. cset->tasks is consumed
|
|
* first and then ->mg_tasks. After ->mg_tasks, we move onto the
|
|
* next cset.
|
|
*/
|
|
l = l->next;
|
|
|
|
if (l == it->tasks_head)
|
|
l = it->mg_tasks_head->next;
|
|
|
|
if (l == it->mg_tasks_head)
|
|
css_advance_task_iter(it);
|
|
else
|
|
it->task_pos = l;
|
|
|
|
return res;
|
|
}
|
|
|
|
/**
|
|
* css_task_iter_end - finish task iteration
|
|
* @it: the task iterator to finish
|
|
*
|
|
* Finish task iteration started by css_task_iter_start().
|
|
*/
|
|
void css_task_iter_end(struct css_task_iter *it)
|
|
__releases(css_set_rwsem)
|
|
{
|
|
up_read(&css_set_rwsem);
|
|
}
|
|
|
|
/**
|
|
* cgroup_trasnsfer_tasks - move tasks from one cgroup to another
|
|
* @to: cgroup to which the tasks will be moved
|
|
* @from: cgroup in which the tasks currently reside
|
|
*
|
|
* Locking rules between cgroup_post_fork() and the migration path
|
|
* guarantee that, if a task is forking while being migrated, the new child
|
|
* is guaranteed to be either visible in the source cgroup after the
|
|
* parent's migration is complete or put into the target cgroup. No task
|
|
* can slip out of migration through forking.
|
|
*/
|
|
int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
|
|
{
|
|
LIST_HEAD(preloaded_csets);
|
|
struct cgrp_cset_link *link;
|
|
struct css_task_iter it;
|
|
struct task_struct *task;
|
|
int ret;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/* all tasks in @from are being moved, all csets are source */
|
|
down_read(&css_set_rwsem);
|
|
list_for_each_entry(link, &from->cset_links, cset_link)
|
|
cgroup_migrate_add_src(link->cset, to, &preloaded_csets);
|
|
up_read(&css_set_rwsem);
|
|
|
|
ret = cgroup_migrate_prepare_dst(to, &preloaded_csets);
|
|
if (ret)
|
|
goto out_err;
|
|
|
|
/*
|
|
* Migrate tasks one-by-one until @form is empty. This fails iff
|
|
* ->can_attach() fails.
|
|
*/
|
|
do {
|
|
css_task_iter_start(&from->self, &it);
|
|
task = css_task_iter_next(&it);
|
|
if (task)
|
|
get_task_struct(task);
|
|
css_task_iter_end(&it);
|
|
|
|
if (task) {
|
|
ret = cgroup_migrate(to, task, false);
|
|
put_task_struct(task);
|
|
}
|
|
} while (task && !ret);
|
|
out_err:
|
|
cgroup_migrate_finish(&preloaded_csets);
|
|
mutex_unlock(&cgroup_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Stuff for reading the 'tasks'/'procs' files.
|
|
*
|
|
* Reading this file can return large amounts of data if a cgroup has
|
|
* *lots* of attached tasks. So it may need several calls to read(),
|
|
* but we cannot guarantee that the information we produce is correct
|
|
* unless we produce it entirely atomically.
|
|
*
|
|
*/
|
|
|
|
/* which pidlist file are we talking about? */
|
|
enum cgroup_filetype {
|
|
CGROUP_FILE_PROCS,
|
|
CGROUP_FILE_TASKS,
|
|
};
|
|
|
|
/*
|
|
* A pidlist is a list of pids that virtually represents the contents of one
|
|
* of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
|
|
* a pair (one each for procs, tasks) for each pid namespace that's relevant
|
|
* to the cgroup.
|
|
*/
|
|
struct cgroup_pidlist {
|
|
/*
|
|
* used to find which pidlist is wanted. doesn't change as long as
|
|
* this particular list stays in the list.
|
|
*/
|
|
struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
|
|
/* array of xids */
|
|
pid_t *list;
|
|
/* how many elements the above list has */
|
|
int length;
|
|
/* each of these stored in a list by its cgroup */
|
|
struct list_head links;
|
|
/* pointer to the cgroup we belong to, for list removal purposes */
|
|
struct cgroup *owner;
|
|
/* for delayed destruction */
|
|
struct delayed_work destroy_dwork;
|
|
};
|
|
|
|
/*
|
|
* The following two functions "fix" the issue where there are more pids
|
|
* than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
|
|
* TODO: replace with a kernel-wide solution to this problem
|
|
*/
|
|
#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
|
|
static void *pidlist_allocate(int count)
|
|
{
|
|
if (PIDLIST_TOO_LARGE(count))
|
|
return vmalloc(count * sizeof(pid_t));
|
|
else
|
|
return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
|
|
}
|
|
|
|
static void pidlist_free(void *p)
|
|
{
|
|
kvfree(p);
|
|
}
|
|
|
|
/*
|
|
* Used to destroy all pidlists lingering waiting for destroy timer. None
|
|
* should be left afterwards.
|
|
*/
|
|
static void cgroup_pidlist_destroy_all(struct cgroup *cgrp)
|
|
{
|
|
struct cgroup_pidlist *l, *tmp_l;
|
|
|
|
mutex_lock(&cgrp->pidlist_mutex);
|
|
list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
|
|
mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
|
|
mutex_unlock(&cgrp->pidlist_mutex);
|
|
|
|
flush_workqueue(cgroup_pidlist_destroy_wq);
|
|
BUG_ON(!list_empty(&cgrp->pidlists));
|
|
}
|
|
|
|
static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
|
|
{
|
|
struct delayed_work *dwork = to_delayed_work(work);
|
|
struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
|
|
destroy_dwork);
|
|
struct cgroup_pidlist *tofree = NULL;
|
|
|
|
mutex_lock(&l->owner->pidlist_mutex);
|
|
|
|
/*
|
|
* Destroy iff we didn't get queued again. The state won't change
|
|
* as destroy_dwork can only be queued while locked.
|
|
*/
|
|
if (!delayed_work_pending(dwork)) {
|
|
list_del(&l->links);
|
|
pidlist_free(l->list);
|
|
put_pid_ns(l->key.ns);
|
|
tofree = l;
|
|
}
|
|
|
|
mutex_unlock(&l->owner->pidlist_mutex);
|
|
kfree(tofree);
|
|
}
|
|
|
|
/*
|
|
* pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
|
|
* Returns the number of unique elements.
|
|
*/
|
|
static int pidlist_uniq(pid_t *list, int length)
|
|
{
|
|
int src, dest = 1;
|
|
|
|
/*
|
|
* we presume the 0th element is unique, so i starts at 1. trivial
|
|
* edge cases first; no work needs to be done for either
|
|
*/
|
|
if (length == 0 || length == 1)
|
|
return length;
|
|
/* src and dest walk down the list; dest counts unique elements */
|
|
for (src = 1; src < length; src++) {
|
|
/* find next unique element */
|
|
while (list[src] == list[src-1]) {
|
|
src++;
|
|
if (src == length)
|
|
goto after;
|
|
}
|
|
/* dest always points to where the next unique element goes */
|
|
list[dest] = list[src];
|
|
dest++;
|
|
}
|
|
after:
|
|
return dest;
|
|
}
|
|
|
|
/*
|
|
* The two pid files - task and cgroup.procs - guaranteed that the result
|
|
* is sorted, which forced this whole pidlist fiasco. As pid order is
|
|
* different per namespace, each namespace needs differently sorted list,
|
|
* making it impossible to use, for example, single rbtree of member tasks
|
|
* sorted by task pointer. As pidlists can be fairly large, allocating one
|
|
* per open file is dangerous, so cgroup had to implement shared pool of
|
|
* pidlists keyed by cgroup and namespace.
|
|
*
|
|
* All this extra complexity was caused by the original implementation
|
|
* committing to an entirely unnecessary property. In the long term, we
|
|
* want to do away with it. Explicitly scramble sort order if on the
|
|
* default hierarchy so that no such expectation exists in the new
|
|
* interface.
|
|
*
|
|
* Scrambling is done by swapping every two consecutive bits, which is
|
|
* non-identity one-to-one mapping which disturbs sort order sufficiently.
|
|
*/
|
|
static pid_t pid_fry(pid_t pid)
|
|
{
|
|
unsigned a = pid & 0x55555555;
|
|
unsigned b = pid & 0xAAAAAAAA;
|
|
|
|
return (a << 1) | (b >> 1);
|
|
}
|
|
|
|
static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid)
|
|
{
|
|
if (cgroup_on_dfl(cgrp))
|
|
return pid_fry(pid);
|
|
else
|
|
return pid;
|
|
}
|
|
|
|
static int cmppid(const void *a, const void *b)
|
|
{
|
|
return *(pid_t *)a - *(pid_t *)b;
|
|
}
|
|
|
|
static int fried_cmppid(const void *a, const void *b)
|
|
{
|
|
return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b);
|
|
}
|
|
|
|
static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
|
|
enum cgroup_filetype type)
|
|
{
|
|
struct cgroup_pidlist *l;
|
|
/* don't need task_nsproxy() if we're looking at ourself */
|
|
struct pid_namespace *ns = task_active_pid_ns(current);
|
|
|
|
lockdep_assert_held(&cgrp->pidlist_mutex);
|
|
|
|
list_for_each_entry(l, &cgrp->pidlists, links)
|
|
if (l->key.type == type && l->key.ns == ns)
|
|
return l;
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* find the appropriate pidlist for our purpose (given procs vs tasks)
|
|
* returns with the lock on that pidlist already held, and takes care
|
|
* of the use count, or returns NULL with no locks held if we're out of
|
|
* memory.
|
|
*/
|
|
static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
|
|
enum cgroup_filetype type)
|
|
{
|
|
struct cgroup_pidlist *l;
|
|
|
|
lockdep_assert_held(&cgrp->pidlist_mutex);
|
|
|
|
l = cgroup_pidlist_find(cgrp, type);
|
|
if (l)
|
|
return l;
|
|
|
|
/* entry not found; create a new one */
|
|
l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
|
|
if (!l)
|
|
return l;
|
|
|
|
INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
|
|
l->key.type = type;
|
|
/* don't need task_nsproxy() if we're looking at ourself */
|
|
l->key.ns = get_pid_ns(task_active_pid_ns(current));
|
|
l->owner = cgrp;
|
|
list_add(&l->links, &cgrp->pidlists);
|
|
return l;
|
|
}
|
|
|
|
/*
|
|
* Load a cgroup's pidarray with either procs' tgids or tasks' pids
|
|
*/
|
|
static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
|
|
struct cgroup_pidlist **lp)
|
|
{
|
|
pid_t *array;
|
|
int length;
|
|
int pid, n = 0; /* used for populating the array */
|
|
struct css_task_iter it;
|
|
struct task_struct *tsk;
|
|
struct cgroup_pidlist *l;
|
|
|
|
lockdep_assert_held(&cgrp->pidlist_mutex);
|
|
|
|
/*
|
|
* If cgroup gets more users after we read count, we won't have
|
|
* enough space - tough. This race is indistinguishable to the
|
|
* caller from the case that the additional cgroup users didn't
|
|
* show up until sometime later on.
|
|
*/
|
|
length = cgroup_task_count(cgrp);
|
|
array = pidlist_allocate(length);
|
|
if (!array)
|
|
return -ENOMEM;
|
|
/* now, populate the array */
|
|
css_task_iter_start(&cgrp->self, &it);
|
|
while ((tsk = css_task_iter_next(&it))) {
|
|
if (unlikely(n == length))
|
|
break;
|
|
/* get tgid or pid for procs or tasks file respectively */
|
|
if (type == CGROUP_FILE_PROCS)
|
|
pid = task_tgid_vnr(tsk);
|
|
else
|
|
pid = task_pid_vnr(tsk);
|
|
if (pid > 0) /* make sure to only use valid results */
|
|
array[n++] = pid;
|
|
}
|
|
css_task_iter_end(&it);
|
|
length = n;
|
|
/* now sort & (if procs) strip out duplicates */
|
|
if (cgroup_on_dfl(cgrp))
|
|
sort(array, length, sizeof(pid_t), fried_cmppid, NULL);
|
|
else
|
|
sort(array, length, sizeof(pid_t), cmppid, NULL);
|
|
if (type == CGROUP_FILE_PROCS)
|
|
length = pidlist_uniq(array, length);
|
|
|
|
l = cgroup_pidlist_find_create(cgrp, type);
|
|
if (!l) {
|
|
pidlist_free(array);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* store array, freeing old if necessary */
|
|
pidlist_free(l->list);
|
|
l->list = array;
|
|
l->length = length;
|
|
*lp = l;
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroupstats_build - build and fill cgroupstats
|
|
* @stats: cgroupstats to fill information into
|
|
* @dentry: A dentry entry belonging to the cgroup for which stats have
|
|
* been requested.
|
|
*
|
|
* Build and fill cgroupstats so that taskstats can export it to user
|
|
* space.
|
|
*/
|
|
int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
|
|
{
|
|
struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
|
|
struct cgroup *cgrp;
|
|
struct css_task_iter it;
|
|
struct task_struct *tsk;
|
|
|
|
/* it should be kernfs_node belonging to cgroupfs and is a directory */
|
|
if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
|
|
kernfs_type(kn) != KERNFS_DIR)
|
|
return -EINVAL;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/*
|
|
* We aren't being called from kernfs and there's no guarantee on
|
|
* @kn->priv's validity. For this and css_tryget_online_from_dir(),
|
|
* @kn->priv is RCU safe. Let's do the RCU dancing.
|
|
*/
|
|
rcu_read_lock();
|
|
cgrp = rcu_dereference(kn->priv);
|
|
if (!cgrp || cgroup_is_dead(cgrp)) {
|
|
rcu_read_unlock();
|
|
mutex_unlock(&cgroup_mutex);
|
|
return -ENOENT;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
css_task_iter_start(&cgrp->self, &it);
|
|
while ((tsk = css_task_iter_next(&it))) {
|
|
switch (tsk->state) {
|
|
case TASK_RUNNING:
|
|
stats->nr_running++;
|
|
break;
|
|
case TASK_INTERRUPTIBLE:
|
|
stats->nr_sleeping++;
|
|
break;
|
|
case TASK_UNINTERRUPTIBLE:
|
|
stats->nr_uninterruptible++;
|
|
break;
|
|
case TASK_STOPPED:
|
|
stats->nr_stopped++;
|
|
break;
|
|
default:
|
|
if (delayacct_is_task_waiting_on_io(tsk))
|
|
stats->nr_io_wait++;
|
|
break;
|
|
}
|
|
}
|
|
css_task_iter_end(&it);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
|
|
/*
|
|
* seq_file methods for the tasks/procs files. The seq_file position is the
|
|
* next pid to display; the seq_file iterator is a pointer to the pid
|
|
* in the cgroup->l->list array.
|
|
*/
|
|
|
|
static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
|
|
{
|
|
/*
|
|
* Initially we receive a position value that corresponds to
|
|
* one more than the last pid shown (or 0 on the first call or
|
|
* after a seek to the start). Use a binary-search to find the
|
|
* next pid to display, if any
|
|
*/
|
|
struct kernfs_open_file *of = s->private;
|
|
struct cgroup *cgrp = seq_css(s)->cgroup;
|
|
struct cgroup_pidlist *l;
|
|
enum cgroup_filetype type = seq_cft(s)->private;
|
|
int index = 0, pid = *pos;
|
|
int *iter, ret;
|
|
|
|
mutex_lock(&cgrp->pidlist_mutex);
|
|
|
|
/*
|
|
* !NULL @of->priv indicates that this isn't the first start()
|
|
* after open. If the matching pidlist is around, we can use that.
|
|
* Look for it. Note that @of->priv can't be used directly. It
|
|
* could already have been destroyed.
|
|
*/
|
|
if (of->priv)
|
|
of->priv = cgroup_pidlist_find(cgrp, type);
|
|
|
|
/*
|
|
* Either this is the first start() after open or the matching
|
|
* pidlist has been destroyed inbetween. Create a new one.
|
|
*/
|
|
if (!of->priv) {
|
|
ret = pidlist_array_load(cgrp, type,
|
|
(struct cgroup_pidlist **)&of->priv);
|
|
if (ret)
|
|
return ERR_PTR(ret);
|
|
}
|
|
l = of->priv;
|
|
|
|
if (pid) {
|
|
int end = l->length;
|
|
|
|
while (index < end) {
|
|
int mid = (index + end) / 2;
|
|
if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) {
|
|
index = mid;
|
|
break;
|
|
} else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid)
|
|
index = mid + 1;
|
|
else
|
|
end = mid;
|
|
}
|
|
}
|
|
/* If we're off the end of the array, we're done */
|
|
if (index >= l->length)
|
|
return NULL;
|
|
/* Update the abstract position to be the actual pid that we found */
|
|
iter = l->list + index;
|
|
*pos = cgroup_pid_fry(cgrp, *iter);
|
|
return iter;
|
|
}
|
|
|
|
static void cgroup_pidlist_stop(struct seq_file *s, void *v)
|
|
{
|
|
struct kernfs_open_file *of = s->private;
|
|
struct cgroup_pidlist *l = of->priv;
|
|
|
|
if (l)
|
|
mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
|
|
CGROUP_PIDLIST_DESTROY_DELAY);
|
|
mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
|
|
}
|
|
|
|
static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
|
|
{
|
|
struct kernfs_open_file *of = s->private;
|
|
struct cgroup_pidlist *l = of->priv;
|
|
pid_t *p = v;
|
|
pid_t *end = l->list + l->length;
|
|
/*
|
|
* Advance to the next pid in the array. If this goes off the
|
|
* end, we're done
|
|
*/
|
|
p++;
|
|
if (p >= end) {
|
|
return NULL;
|
|
} else {
|
|
*pos = cgroup_pid_fry(seq_css(s)->cgroup, *p);
|
|
return p;
|
|
}
|
|
}
|
|
|
|
static int cgroup_pidlist_show(struct seq_file *s, void *v)
|
|
{
|
|
seq_printf(s, "%d\n", *(int *)v);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
return notify_on_release(css->cgroup);
|
|
}
|
|
|
|
static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
|
|
struct cftype *cft, u64 val)
|
|
{
|
|
if (val)
|
|
set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
|
|
else
|
|
clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
|
|
return 0;
|
|
}
|
|
|
|
static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
|
}
|
|
|
|
static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
|
|
struct cftype *cft, u64 val)
|
|
{
|
|
if (val)
|
|
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
|
else
|
|
clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
|
return 0;
|
|
}
|
|
|
|
/* cgroup core interface files for the default hierarchy */
|
|
static struct cftype cgroup_dfl_base_files[] = {
|
|
{
|
|
.name = "cgroup.procs",
|
|
.file_offset = offsetof(struct cgroup, procs_file),
|
|
.seq_start = cgroup_pidlist_start,
|
|
.seq_next = cgroup_pidlist_next,
|
|
.seq_stop = cgroup_pidlist_stop,
|
|
.seq_show = cgroup_pidlist_show,
|
|
.private = CGROUP_FILE_PROCS,
|
|
.write = cgroup_procs_write,
|
|
},
|
|
{
|
|
.name = "cgroup.controllers",
|
|
.flags = CFTYPE_ONLY_ON_ROOT,
|
|
.seq_show = cgroup_root_controllers_show,
|
|
},
|
|
{
|
|
.name = "cgroup.controllers",
|
|
.flags = CFTYPE_NOT_ON_ROOT,
|
|
.seq_show = cgroup_controllers_show,
|
|
},
|
|
{
|
|
.name = "cgroup.subtree_control",
|
|
.seq_show = cgroup_subtree_control_show,
|
|
.write = cgroup_subtree_control_write,
|
|
},
|
|
{
|
|
.name = "cgroup.events",
|
|
.flags = CFTYPE_NOT_ON_ROOT,
|
|
.file_offset = offsetof(struct cgroup, events_file),
|
|
.seq_show = cgroup_events_show,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
/* cgroup core interface files for the legacy hierarchies */
|
|
static struct cftype cgroup_legacy_base_files[] = {
|
|
{
|
|
.name = "cgroup.procs",
|
|
.seq_start = cgroup_pidlist_start,
|
|
.seq_next = cgroup_pidlist_next,
|
|
.seq_stop = cgroup_pidlist_stop,
|
|
.seq_show = cgroup_pidlist_show,
|
|
.private = CGROUP_FILE_PROCS,
|
|
.write = cgroup_procs_write,
|
|
},
|
|
{
|
|
.name = "cgroup.clone_children",
|
|
.read_u64 = cgroup_clone_children_read,
|
|
.write_u64 = cgroup_clone_children_write,
|
|
},
|
|
{
|
|
.name = "cgroup.sane_behavior",
|
|
.flags = CFTYPE_ONLY_ON_ROOT,
|
|
.seq_show = cgroup_sane_behavior_show,
|
|
},
|
|
{
|
|
.name = "tasks",
|
|
.seq_start = cgroup_pidlist_start,
|
|
.seq_next = cgroup_pidlist_next,
|
|
.seq_stop = cgroup_pidlist_stop,
|
|
.seq_show = cgroup_pidlist_show,
|
|
.private = CGROUP_FILE_TASKS,
|
|
.write = cgroup_tasks_write,
|
|
},
|
|
{
|
|
.name = "notify_on_release",
|
|
.read_u64 = cgroup_read_notify_on_release,
|
|
.write_u64 = cgroup_write_notify_on_release,
|
|
},
|
|
{
|
|
.name = "release_agent",
|
|
.flags = CFTYPE_ONLY_ON_ROOT,
|
|
.seq_show = cgroup_release_agent_show,
|
|
.write = cgroup_release_agent_write,
|
|
.max_write_len = PATH_MAX - 1,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
/*
|
|
* css destruction is four-stage process.
|
|
*
|
|
* 1. Destruction starts. Killing of the percpu_ref is initiated.
|
|
* Implemented in kill_css().
|
|
*
|
|
* 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
|
|
* and thus css_tryget_online() is guaranteed to fail, the css can be
|
|
* offlined by invoking offline_css(). After offlining, the base ref is
|
|
* put. Implemented in css_killed_work_fn().
|
|
*
|
|
* 3. When the percpu_ref reaches zero, the only possible remaining
|
|
* accessors are inside RCU read sections. css_release() schedules the
|
|
* RCU callback.
|
|
*
|
|
* 4. After the grace period, the css can be freed. Implemented in
|
|
* css_free_work_fn().
|
|
*
|
|
* It is actually hairier because both step 2 and 4 require process context
|
|
* and thus involve punting to css->destroy_work adding two additional
|
|
* steps to the already complex sequence.
|
|
*/
|
|
static void css_free_work_fn(struct work_struct *work)
|
|
{
|
|
struct cgroup_subsys_state *css =
|
|
container_of(work, struct cgroup_subsys_state, destroy_work);
|
|
struct cgroup_subsys *ss = css->ss;
|
|
struct cgroup *cgrp = css->cgroup;
|
|
struct cgroup_file *cfile;
|
|
|
|
percpu_ref_exit(&css->refcnt);
|
|
|
|
list_for_each_entry(cfile, &css->files, node)
|
|
kernfs_put(cfile->kn);
|
|
|
|
if (ss) {
|
|
/* css free path */
|
|
int id = css->id;
|
|
|
|
if (css->parent)
|
|
css_put(css->parent);
|
|
|
|
ss->css_free(css);
|
|
cgroup_idr_remove(&ss->css_idr, id);
|
|
cgroup_put(cgrp);
|
|
} else {
|
|
/* cgroup free path */
|
|
atomic_dec(&cgrp->root->nr_cgrps);
|
|
cgroup_pidlist_destroy_all(cgrp);
|
|
cancel_work_sync(&cgrp->release_agent_work);
|
|
|
|
if (cgroup_parent(cgrp)) {
|
|
/*
|
|
* We get a ref to the parent, and put the ref when
|
|
* this cgroup is being freed, so it's guaranteed
|
|
* that the parent won't be destroyed before its
|
|
* children.
|
|
*/
|
|
cgroup_put(cgroup_parent(cgrp));
|
|
kernfs_put(cgrp->kn);
|
|
kfree(cgrp);
|
|
} else {
|
|
/*
|
|
* This is root cgroup's refcnt reaching zero,
|
|
* which indicates that the root should be
|
|
* released.
|
|
*/
|
|
cgroup_destroy_root(cgrp->root);
|
|
}
|
|
}
|
|
}
|
|
|
|
static void css_free_rcu_fn(struct rcu_head *rcu_head)
|
|
{
|
|
struct cgroup_subsys_state *css =
|
|
container_of(rcu_head, struct cgroup_subsys_state, rcu_head);
|
|
|
|
INIT_WORK(&css->destroy_work, css_free_work_fn);
|
|
queue_work(cgroup_destroy_wq, &css->destroy_work);
|
|
}
|
|
|
|
static void css_release_work_fn(struct work_struct *work)
|
|
{
|
|
struct cgroup_subsys_state *css =
|
|
container_of(work, struct cgroup_subsys_state, destroy_work);
|
|
struct cgroup_subsys *ss = css->ss;
|
|
struct cgroup *cgrp = css->cgroup;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
css->flags |= CSS_RELEASED;
|
|
list_del_rcu(&css->sibling);
|
|
|
|
if (ss) {
|
|
/* css release path */
|
|
cgroup_idr_replace(&ss->css_idr, NULL, css->id);
|
|
if (ss->css_released)
|
|
ss->css_released(css);
|
|
} else {
|
|
/* cgroup release path */
|
|
cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
|
|
cgrp->id = -1;
|
|
|
|
/*
|
|
* There are two control paths which try to determine
|
|
* cgroup from dentry without going through kernfs -
|
|
* cgroupstats_build() and css_tryget_online_from_dir().
|
|
* Those are supported by RCU protecting clearing of
|
|
* cgrp->kn->priv backpointer.
|
|
*/
|
|
RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL);
|
|
}
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
call_rcu(&css->rcu_head, css_free_rcu_fn);
|
|
}
|
|
|
|
static void css_release(struct percpu_ref *ref)
|
|
{
|
|
struct cgroup_subsys_state *css =
|
|
container_of(ref, struct cgroup_subsys_state, refcnt);
|
|
|
|
INIT_WORK(&css->destroy_work, css_release_work_fn);
|
|
queue_work(cgroup_destroy_wq, &css->destroy_work);
|
|
}
|
|
|
|
static void init_and_link_css(struct cgroup_subsys_state *css,
|
|
struct cgroup_subsys *ss, struct cgroup *cgrp)
|
|
{
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
cgroup_get(cgrp);
|
|
|
|
memset(css, 0, sizeof(*css));
|
|
css->cgroup = cgrp;
|
|
css->ss = ss;
|
|
INIT_LIST_HEAD(&css->sibling);
|
|
INIT_LIST_HEAD(&css->children);
|
|
INIT_LIST_HEAD(&css->files);
|
|
css->serial_nr = css_serial_nr_next++;
|
|
|
|
if (cgroup_parent(cgrp)) {
|
|
css->parent = cgroup_css(cgroup_parent(cgrp), ss);
|
|
css_get(css->parent);
|
|
}
|
|
|
|
BUG_ON(cgroup_css(cgrp, ss));
|
|
}
|
|
|
|
/* invoke ->css_online() on a new CSS and mark it online if successful */
|
|
static int online_css(struct cgroup_subsys_state *css)
|
|
{
|
|
struct cgroup_subsys *ss = css->ss;
|
|
int ret = 0;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
if (ss->css_online)
|
|
ret = ss->css_online(css);
|
|
if (!ret) {
|
|
css->flags |= CSS_ONLINE;
|
|
rcu_assign_pointer(css->cgroup->subsys[ss->id], css);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/* if the CSS is online, invoke ->css_offline() on it and mark it offline */
|
|
static void offline_css(struct cgroup_subsys_state *css)
|
|
{
|
|
struct cgroup_subsys *ss = css->ss;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
if (!(css->flags & CSS_ONLINE))
|
|
return;
|
|
|
|
if (ss->css_offline)
|
|
ss->css_offline(css);
|
|
|
|
css->flags &= ~CSS_ONLINE;
|
|
RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL);
|
|
|
|
wake_up_all(&css->cgroup->offline_waitq);
|
|
}
|
|
|
|
/**
|
|
* create_css - create a cgroup_subsys_state
|
|
* @cgrp: the cgroup new css will be associated with
|
|
* @ss: the subsys of new css
|
|
* @visible: whether to create control knobs for the new css or not
|
|
*
|
|
* Create a new css associated with @cgrp - @ss pair. On success, the new
|
|
* css is online and installed in @cgrp with all interface files created if
|
|
* @visible. Returns 0 on success, -errno on failure.
|
|
*/
|
|
static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,
|
|
bool visible)
|
|
{
|
|
struct cgroup *parent = cgroup_parent(cgrp);
|
|
struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss);
|
|
struct cgroup_subsys_state *css;
|
|
int err;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
css = ss->css_alloc(parent_css);
|
|
if (IS_ERR(css))
|
|
return PTR_ERR(css);
|
|
|
|
init_and_link_css(css, ss, cgrp);
|
|
|
|
err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL);
|
|
if (err)
|
|
goto err_free_css;
|
|
|
|
err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL);
|
|
if (err < 0)
|
|
goto err_free_percpu_ref;
|
|
css->id = err;
|
|
|
|
if (visible) {
|
|
err = css_populate_dir(css, NULL);
|
|
if (err)
|
|
goto err_free_id;
|
|
}
|
|
|
|
/* @css is ready to be brought online now, make it visible */
|
|
list_add_tail_rcu(&css->sibling, &parent_css->children);
|
|
cgroup_idr_replace(&ss->css_idr, css, css->id);
|
|
|
|
err = online_css(css);
|
|
if (err)
|
|
goto err_list_del;
|
|
|
|
if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
|
|
cgroup_parent(parent)) {
|
|
pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
|
|
current->comm, current->pid, ss->name);
|
|
if (!strcmp(ss->name, "memory"))
|
|
pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n");
|
|
ss->warned_broken_hierarchy = true;
|
|
}
|
|
|
|
return 0;
|
|
|
|
err_list_del:
|
|
list_del_rcu(&css->sibling);
|
|
css_clear_dir(css, NULL);
|
|
err_free_id:
|
|
cgroup_idr_remove(&ss->css_idr, css->id);
|
|
err_free_percpu_ref:
|
|
percpu_ref_exit(&css->refcnt);
|
|
err_free_css:
|
|
call_rcu(&css->rcu_head, css_free_rcu_fn);
|
|
return err;
|
|
}
|
|
|
|
static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
|
|
umode_t mode)
|
|
{
|
|
struct cgroup *parent, *cgrp;
|
|
struct cgroup_root *root;
|
|
struct cgroup_subsys *ss;
|
|
struct kernfs_node *kn;
|
|
int ssid, ret;
|
|
|
|
/* Do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable.
|
|
*/
|
|
if (strchr(name, '\n'))
|
|
return -EINVAL;
|
|
|
|
parent = cgroup_kn_lock_live(parent_kn);
|
|
if (!parent)
|
|
return -ENODEV;
|
|
root = parent->root;
|
|
|
|
/* allocate the cgroup and its ID, 0 is reserved for the root */
|
|
cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL);
|
|
if (!cgrp) {
|
|
ret = -ENOMEM;
|
|
goto out_unlock;
|
|
}
|
|
|
|
ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL);
|
|
if (ret)
|
|
goto out_free_cgrp;
|
|
|
|
/*
|
|
* Temporarily set the pointer to NULL, so idr_find() won't return
|
|
* a half-baked cgroup.
|
|
*/
|
|
cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_KERNEL);
|
|
if (cgrp->id < 0) {
|
|
ret = -ENOMEM;
|
|
goto out_cancel_ref;
|
|
}
|
|
|
|
init_cgroup_housekeeping(cgrp);
|
|
|
|
cgrp->self.parent = &parent->self;
|
|
cgrp->root = root;
|
|
|
|
if (notify_on_release(parent))
|
|
set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
|
|
|
|
if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags))
|
|
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
|
|
|
|
/* create the directory */
|
|
kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
|
|
if (IS_ERR(kn)) {
|
|
ret = PTR_ERR(kn);
|
|
goto out_free_id;
|
|
}
|
|
cgrp->kn = kn;
|
|
|
|
/*
|
|
* This extra ref will be put in cgroup_free_fn() and guarantees
|
|
* that @cgrp->kn is always accessible.
|
|
*/
|
|
kernfs_get(kn);
|
|
|
|
cgrp->self.serial_nr = css_serial_nr_next++;
|
|
|
|
/* allocation complete, commit to creation */
|
|
list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children);
|
|
atomic_inc(&root->nr_cgrps);
|
|
cgroup_get(parent);
|
|
|
|
/*
|
|
* @cgrp is now fully operational. If something fails after this
|
|
* point, it'll be released via the normal destruction path.
|
|
*/
|
|
cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id);
|
|
|
|
ret = cgroup_kn_set_ugid(kn);
|
|
if (ret)
|
|
goto out_destroy;
|
|
|
|
ret = css_populate_dir(&cgrp->self, NULL);
|
|
if (ret)
|
|
goto out_destroy;
|
|
|
|
/* let's create and online css's */
|
|
for_each_subsys(ss, ssid) {
|
|
if (parent->child_subsys_mask & (1 << ssid)) {
|
|
ret = create_css(cgrp, ss,
|
|
parent->subtree_control & (1 << ssid));
|
|
if (ret)
|
|
goto out_destroy;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* On the default hierarchy, a child doesn't automatically inherit
|
|
* subtree_control from the parent. Each is configured manually.
|
|
*/
|
|
if (!cgroup_on_dfl(cgrp)) {
|
|
cgrp->subtree_control = parent->subtree_control;
|
|
cgroup_refresh_child_subsys_mask(cgrp);
|
|
}
|
|
|
|
kernfs_activate(kn);
|
|
|
|
ret = 0;
|
|
goto out_unlock;
|
|
|
|
out_free_id:
|
|
cgroup_idr_remove(&root->cgroup_idr, cgrp->id);
|
|
out_cancel_ref:
|
|
percpu_ref_exit(&cgrp->self.refcnt);
|
|
out_free_cgrp:
|
|
kfree(cgrp);
|
|
out_unlock:
|
|
cgroup_kn_unlock(parent_kn);
|
|
return ret;
|
|
|
|
out_destroy:
|
|
cgroup_destroy_locked(cgrp);
|
|
goto out_unlock;
|
|
}
|
|
|
|
/*
|
|
* This is called when the refcnt of a css is confirmed to be killed.
|
|
* css_tryget_online() is now guaranteed to fail. Tell the subsystem to
|
|
* initate destruction and put the css ref from kill_css().
|
|
*/
|
|
static void css_killed_work_fn(struct work_struct *work)
|
|
{
|
|
struct cgroup_subsys_state *css =
|
|
container_of(work, struct cgroup_subsys_state, destroy_work);
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
offline_css(css);
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
css_put(css);
|
|
}
|
|
|
|
/* css kill confirmation processing requires process context, bounce */
|
|
static void css_killed_ref_fn(struct percpu_ref *ref)
|
|
{
|
|
struct cgroup_subsys_state *css =
|
|
container_of(ref, struct cgroup_subsys_state, refcnt);
|
|
|
|
INIT_WORK(&css->destroy_work, css_killed_work_fn);
|
|
queue_work(cgroup_destroy_wq, &css->destroy_work);
|
|
}
|
|
|
|
/**
|
|
* kill_css - destroy a css
|
|
* @css: css to destroy
|
|
*
|
|
* This function initiates destruction of @css by removing cgroup interface
|
|
* files and putting its base reference. ->css_offline() will be invoked
|
|
* asynchronously once css_tryget_online() is guaranteed to fail and when
|
|
* the reference count reaches zero, @css will be released.
|
|
*/
|
|
static void kill_css(struct cgroup_subsys_state *css)
|
|
{
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
/*
|
|
* This must happen before css is disassociated with its cgroup.
|
|
* See seq_css() for details.
|
|
*/
|
|
css_clear_dir(css, NULL);
|
|
|
|
/*
|
|
* Killing would put the base ref, but we need to keep it alive
|
|
* until after ->css_offline().
|
|
*/
|
|
css_get(css);
|
|
|
|
/*
|
|
* cgroup core guarantees that, by the time ->css_offline() is
|
|
* invoked, no new css reference will be given out via
|
|
* css_tryget_online(). We can't simply call percpu_ref_kill() and
|
|
* proceed to offlining css's because percpu_ref_kill() doesn't
|
|
* guarantee that the ref is seen as killed on all CPUs on return.
|
|
*
|
|
* Use percpu_ref_kill_and_confirm() to get notifications as each
|
|
* css is confirmed to be seen as killed on all CPUs.
|
|
*/
|
|
percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn);
|
|
}
|
|
|
|
/**
|
|
* cgroup_destroy_locked - the first stage of cgroup destruction
|
|
* @cgrp: cgroup to be destroyed
|
|
*
|
|
* css's make use of percpu refcnts whose killing latency shouldn't be
|
|
* exposed to userland and are RCU protected. Also, cgroup core needs to
|
|
* guarantee that css_tryget_online() won't succeed by the time
|
|
* ->css_offline() is invoked. To satisfy all the requirements,
|
|
* destruction is implemented in the following two steps.
|
|
*
|
|
* s1. Verify @cgrp can be destroyed and mark it dying. Remove all
|
|
* userland visible parts and start killing the percpu refcnts of
|
|
* css's. Set up so that the next stage will be kicked off once all
|
|
* the percpu refcnts are confirmed to be killed.
|
|
*
|
|
* s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
|
|
* rest of destruction. Once all cgroup references are gone, the
|
|
* cgroup is RCU-freed.
|
|
*
|
|
* This function implements s1. After this step, @cgrp is gone as far as
|
|
* the userland is concerned and a new cgroup with the same name may be
|
|
* created. As cgroup doesn't care about the names internally, this
|
|
* doesn't cause any problem.
|
|
*/
|
|
static int cgroup_destroy_locked(struct cgroup *cgrp)
|
|
__releases(&cgroup_mutex) __acquires(&cgroup_mutex)
|
|
{
|
|
struct cgroup_subsys_state *css;
|
|
bool empty;
|
|
int ssid;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
/*
|
|
* css_set_rwsem synchronizes access to ->cset_links and prevents
|
|
* @cgrp from being removed while put_css_set() is in progress.
|
|
*/
|
|
down_read(&css_set_rwsem);
|
|
empty = list_empty(&cgrp->cset_links);
|
|
up_read(&css_set_rwsem);
|
|
if (!empty)
|
|
return -EBUSY;
|
|
|
|
/*
|
|
* Make sure there's no live children. We can't test emptiness of
|
|
* ->self.children as dead children linger on it while being
|
|
* drained; otherwise, "rmdir parent/child parent" may fail.
|
|
*/
|
|
if (css_has_online_children(&cgrp->self))
|
|
return -EBUSY;
|
|
|
|
/*
|
|
* Mark @cgrp dead. This prevents further task migration and child
|
|
* creation by disabling cgroup_lock_live_group().
|
|
*/
|
|
cgrp->self.flags &= ~CSS_ONLINE;
|
|
|
|
/* initiate massacre of all css's */
|
|
for_each_css(css, ssid, cgrp)
|
|
kill_css(css);
|
|
|
|
/*
|
|
* Remove @cgrp directory along with the base files. @cgrp has an
|
|
* extra ref on its kn.
|
|
*/
|
|
kernfs_remove(cgrp->kn);
|
|
|
|
check_for_release(cgroup_parent(cgrp));
|
|
|
|
/* put the base reference */
|
|
percpu_ref_kill(&cgrp->self.refcnt);
|
|
|
|
return 0;
|
|
};
|
|
|
|
static int cgroup_rmdir(struct kernfs_node *kn)
|
|
{
|
|
struct cgroup *cgrp;
|
|
int ret = 0;
|
|
|
|
cgrp = cgroup_kn_lock_live(kn);
|
|
if (!cgrp)
|
|
return 0;
|
|
|
|
ret = cgroup_destroy_locked(cgrp);
|
|
|
|
cgroup_kn_unlock(kn);
|
|
return ret;
|
|
}
|
|
|
|
static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
|
|
.remount_fs = cgroup_remount,
|
|
.show_options = cgroup_show_options,
|
|
.mkdir = cgroup_mkdir,
|
|
.rmdir = cgroup_rmdir,
|
|
.rename = cgroup_rename,
|
|
};
|
|
|
|
static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early)
|
|
{
|
|
struct cgroup_subsys_state *css;
|
|
|
|
printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
idr_init(&ss->css_idr);
|
|
INIT_LIST_HEAD(&ss->cfts);
|
|
|
|
/* Create the root cgroup state for this subsystem */
|
|
ss->root = &cgrp_dfl_root;
|
|
css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss));
|
|
/* We don't handle early failures gracefully */
|
|
BUG_ON(IS_ERR(css));
|
|
init_and_link_css(css, ss, &cgrp_dfl_root.cgrp);
|
|
|
|
/*
|
|
* Root csses are never destroyed and we can't initialize
|
|
* percpu_ref during early init. Disable refcnting.
|
|
*/
|
|
css->flags |= CSS_NO_REF;
|
|
|
|
if (early) {
|
|
/* allocation can't be done safely during early init */
|
|
css->id = 1;
|
|
} else {
|
|
css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL);
|
|
BUG_ON(css->id < 0);
|
|
}
|
|
|
|
/* Update the init_css_set to contain a subsys
|
|
* pointer to this state - since the subsystem is
|
|
* newly registered, all tasks and hence the
|
|
* init_css_set is in the subsystem's root cgroup. */
|
|
init_css_set.subsys[ss->id] = css;
|
|
|
|
have_fork_callback |= (bool)ss->fork << ss->id;
|
|
have_exit_callback |= (bool)ss->exit << ss->id;
|
|
have_canfork_callback |= (bool)ss->can_fork << ss->id;
|
|
|
|
/* At system boot, before all subsystems have been
|
|
* registered, no tasks have been forked, so we don't
|
|
* need to invoke fork callbacks here. */
|
|
BUG_ON(!list_empty(&init_task.tasks));
|
|
|
|
BUG_ON(online_css(css));
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
}
|
|
|
|
/**
|
|
* cgroup_init_early - cgroup initialization at system boot
|
|
*
|
|
* Initialize cgroups at system boot, and initialize any
|
|
* subsystems that request early init.
|
|
*/
|
|
int __init cgroup_init_early(void)
|
|
{
|
|
static struct cgroup_sb_opts __initdata opts;
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
init_cgroup_root(&cgrp_dfl_root, &opts);
|
|
cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF;
|
|
|
|
RCU_INIT_POINTER(init_task.cgroups, &init_css_set);
|
|
|
|
for_each_subsys(ss, i) {
|
|
WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id,
|
|
"invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p name:id=%d:%s\n",
|
|
i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free,
|
|
ss->id, ss->name);
|
|
WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN,
|
|
"cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]);
|
|
|
|
ss->id = i;
|
|
ss->name = cgroup_subsys_name[i];
|
|
if (!ss->legacy_name)
|
|
ss->legacy_name = cgroup_subsys_name[i];
|
|
|
|
if (ss->early_init)
|
|
cgroup_init_subsys(ss, true);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroup_init - cgroup initialization
|
|
*
|
|
* Register cgroup filesystem and /proc file, and initialize
|
|
* any subsystems that didn't request early init.
|
|
*/
|
|
int __init cgroup_init(void)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
unsigned long key;
|
|
int ssid, err;
|
|
|
|
BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem));
|
|
BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files));
|
|
BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files));
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/* Add init_css_set to the hash table */
|
|
key = css_set_hash(init_css_set.subsys);
|
|
hash_add(css_set_table, &init_css_set.hlist, key);
|
|
|
|
BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0));
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
for_each_subsys(ss, ssid) {
|
|
if (ss->early_init) {
|
|
struct cgroup_subsys_state *css =
|
|
init_css_set.subsys[ss->id];
|
|
|
|
css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2,
|
|
GFP_KERNEL);
|
|
BUG_ON(css->id < 0);
|
|
} else {
|
|
cgroup_init_subsys(ss, false);
|
|
}
|
|
|
|
list_add_tail(&init_css_set.e_cset_node[ssid],
|
|
&cgrp_dfl_root.cgrp.e_csets[ssid]);
|
|
|
|
/*
|
|
* Setting dfl_root subsys_mask needs to consider the
|
|
* disabled flag and cftype registration needs kmalloc,
|
|
* both of which aren't available during early_init.
|
|
*/
|
|
if (!cgroup_ssid_enabled(ssid))
|
|
continue;
|
|
|
|
cgrp_dfl_root.subsys_mask |= 1 << ss->id;
|
|
|
|
if (cgroup_legacy_files_on_dfl && !ss->dfl_cftypes)
|
|
ss->dfl_cftypes = ss->legacy_cftypes;
|
|
|
|
if (!ss->dfl_cftypes)
|
|
cgrp_dfl_root_inhibit_ss_mask |= 1 << ss->id;
|
|
|
|
if (ss->dfl_cftypes == ss->legacy_cftypes) {
|
|
WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes));
|
|
} else {
|
|
WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes));
|
|
WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes));
|
|
}
|
|
|
|
if (ss->bind)
|
|
ss->bind(init_css_set.subsys[ssid]);
|
|
}
|
|
|
|
err = sysfs_create_mount_point(fs_kobj, "cgroup");
|
|
if (err)
|
|
return err;
|
|
|
|
err = register_filesystem(&cgroup_fs_type);
|
|
if (err < 0) {
|
|
sysfs_remove_mount_point(fs_kobj, "cgroup");
|
|
return err;
|
|
}
|
|
|
|
proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations);
|
|
return 0;
|
|
}
|
|
|
|
static int __init cgroup_wq_init(void)
|
|
{
|
|
/*
|
|
* There isn't much point in executing destruction path in
|
|
* parallel. Good chunk is serialized with cgroup_mutex anyway.
|
|
* Use 1 for @max_active.
|
|
*
|
|
* We would prefer to do this in cgroup_init() above, but that
|
|
* is called before init_workqueues(): so leave this until after.
|
|
*/
|
|
cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);
|
|
BUG_ON(!cgroup_destroy_wq);
|
|
|
|
/*
|
|
* Used to destroy pidlists and separate to serve as flush domain.
|
|
* Cap @max_active to 1 too.
|
|
*/
|
|
cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
|
|
0, 1);
|
|
BUG_ON(!cgroup_pidlist_destroy_wq);
|
|
|
|
return 0;
|
|
}
|
|
core_initcall(cgroup_wq_init);
|
|
|
|
/*
|
|
* proc_cgroup_show()
|
|
* - Print task's cgroup paths into seq_file, one line for each hierarchy
|
|
* - Used for /proc/<pid>/cgroup.
|
|
*/
|
|
int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
|
|
struct pid *pid, struct task_struct *tsk)
|
|
{
|
|
char *buf, *path;
|
|
int retval;
|
|
struct cgroup_root *root;
|
|
|
|
retval = -ENOMEM;
|
|
buf = kmalloc(PATH_MAX, GFP_KERNEL);
|
|
if (!buf)
|
|
goto out;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
down_read(&css_set_rwsem);
|
|
|
|
for_each_root(root) {
|
|
struct cgroup_subsys *ss;
|
|
struct cgroup *cgrp;
|
|
int ssid, count = 0;
|
|
|
|
if (root == &cgrp_dfl_root && !cgrp_dfl_root_visible)
|
|
continue;
|
|
|
|
seq_printf(m, "%d:", root->hierarchy_id);
|
|
if (root != &cgrp_dfl_root)
|
|
for_each_subsys(ss, ssid)
|
|
if (root->subsys_mask & (1 << ssid))
|
|
seq_printf(m, "%s%s", count++ ? "," : "",
|
|
ss->legacy_name);
|
|
if (strlen(root->name))
|
|
seq_printf(m, "%sname=%s", count ? "," : "",
|
|
root->name);
|
|
seq_putc(m, ':');
|
|
cgrp = task_cgroup_from_root(tsk, root);
|
|
path = cgroup_path(cgrp, buf, PATH_MAX);
|
|
if (!path) {
|
|
retval = -ENAMETOOLONG;
|
|
goto out_unlock;
|
|
}
|
|
seq_puts(m, path);
|
|
seq_putc(m, '\n');
|
|
}
|
|
|
|
retval = 0;
|
|
out_unlock:
|
|
up_read(&css_set_rwsem);
|
|
mutex_unlock(&cgroup_mutex);
|
|
kfree(buf);
|
|
out:
|
|
return retval;
|
|
}
|
|
|
|
/* Display information about each subsystem and each hierarchy */
|
|
static int proc_cgroupstats_show(struct seq_file *m, void *v)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
|
|
/*
|
|
* ideally we don't want subsystems moving around while we do this.
|
|
* cgroup_mutex is also necessary to guarantee an atomic snapshot of
|
|
* subsys/hierarchy state.
|
|
*/
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
for_each_subsys(ss, i)
|
|
seq_printf(m, "%s\t%d\t%d\t%d\n",
|
|
ss->legacy_name, ss->root->hierarchy_id,
|
|
atomic_read(&ss->root->nr_cgrps),
|
|
cgroup_ssid_enabled(i));
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
static int cgroupstats_open(struct inode *inode, struct file *file)
|
|
{
|
|
return single_open(file, proc_cgroupstats_show, NULL);
|
|
}
|
|
|
|
static const struct file_operations proc_cgroupstats_operations = {
|
|
.open = cgroupstats_open,
|
|
.read = seq_read,
|
|
.llseek = seq_lseek,
|
|
.release = single_release,
|
|
};
|
|
|
|
static void **subsys_canfork_priv_p(void *ss_priv[CGROUP_CANFORK_COUNT], int i)
|
|
{
|
|
if (CGROUP_CANFORK_START <= i && i < CGROUP_CANFORK_END)
|
|
return &ss_priv[i - CGROUP_CANFORK_START];
|
|
return NULL;
|
|
}
|
|
|
|
static void *subsys_canfork_priv(void *ss_priv[CGROUP_CANFORK_COUNT], int i)
|
|
{
|
|
void **private = subsys_canfork_priv_p(ss_priv, i);
|
|
return private ? *private : NULL;
|
|
}
|
|
|
|
/**
|
|
* cgroup_fork - initialize cgroup related fields during copy_process()
|
|
* @child: pointer to task_struct of forking parent process.
|
|
*
|
|
* A task is associated with the init_css_set until cgroup_post_fork()
|
|
* attaches it to the parent's css_set. Empty cg_list indicates that
|
|
* @child isn't holding reference to its css_set.
|
|
*/
|
|
void cgroup_fork(struct task_struct *child)
|
|
{
|
|
RCU_INIT_POINTER(child->cgroups, &init_css_set);
|
|
INIT_LIST_HEAD(&child->cg_list);
|
|
}
|
|
|
|
/**
|
|
* cgroup_can_fork - called on a new task before the process is exposed
|
|
* @child: the task in question.
|
|
*
|
|
* This calls the subsystem can_fork() callbacks. If the can_fork() callback
|
|
* returns an error, the fork aborts with that error code. This allows for
|
|
* a cgroup subsystem to conditionally allow or deny new forks.
|
|
*/
|
|
int cgroup_can_fork(struct task_struct *child,
|
|
void *ss_priv[CGROUP_CANFORK_COUNT])
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int i, j, ret;
|
|
|
|
for_each_subsys_which(ss, i, &have_canfork_callback) {
|
|
ret = ss->can_fork(child, subsys_canfork_priv_p(ss_priv, i));
|
|
if (ret)
|
|
goto out_revert;
|
|
}
|
|
|
|
return 0;
|
|
|
|
out_revert:
|
|
for_each_subsys(ss, j) {
|
|
if (j >= i)
|
|
break;
|
|
if (ss->cancel_fork)
|
|
ss->cancel_fork(child, subsys_canfork_priv(ss_priv, j));
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* cgroup_cancel_fork - called if a fork failed after cgroup_can_fork()
|
|
* @child: the task in question
|
|
*
|
|
* This calls the cancel_fork() callbacks if a fork failed *after*
|
|
* cgroup_can_fork() succeded.
|
|
*/
|
|
void cgroup_cancel_fork(struct task_struct *child,
|
|
void *ss_priv[CGROUP_CANFORK_COUNT])
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
for_each_subsys(ss, i)
|
|
if (ss->cancel_fork)
|
|
ss->cancel_fork(child, subsys_canfork_priv(ss_priv, i));
|
|
}
|
|
|
|
/**
|
|
* cgroup_post_fork - called on a new task after adding it to the task list
|
|
* @child: the task in question
|
|
*
|
|
* Adds the task to the list running through its css_set if necessary and
|
|
* call the subsystem fork() callbacks. Has to be after the task is
|
|
* visible on the task list in case we race with the first call to
|
|
* cgroup_task_iter_start() - to guarantee that the new task ends up on its
|
|
* list.
|
|
*/
|
|
void cgroup_post_fork(struct task_struct *child,
|
|
void *old_ss_priv[CGROUP_CANFORK_COUNT])
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
/*
|
|
* This may race against cgroup_enable_task_cg_lists(). As that
|
|
* function sets use_task_css_set_links before grabbing
|
|
* tasklist_lock and we just went through tasklist_lock to add
|
|
* @child, it's guaranteed that either we see the set
|
|
* use_task_css_set_links or cgroup_enable_task_cg_lists() sees
|
|
* @child during its iteration.
|
|
*
|
|
* If we won the race, @child is associated with %current's
|
|
* css_set. Grabbing css_set_rwsem guarantees both that the
|
|
* association is stable, and, on completion of the parent's
|
|
* migration, @child is visible in the source of migration or
|
|
* already in the destination cgroup. This guarantee is necessary
|
|
* when implementing operations which need to migrate all tasks of
|
|
* a cgroup to another.
|
|
*
|
|
* Note that if we lose to cgroup_enable_task_cg_lists(), @child
|
|
* will remain in init_css_set. This is safe because all tasks are
|
|
* in the init_css_set before cg_links is enabled and there's no
|
|
* operation which transfers all tasks out of init_css_set.
|
|
*/
|
|
if (use_task_css_set_links) {
|
|
struct css_set *cset;
|
|
|
|
down_write(&css_set_rwsem);
|
|
cset = task_css_set(current);
|
|
if (list_empty(&child->cg_list)) {
|
|
rcu_assign_pointer(child->cgroups, cset);
|
|
list_add(&child->cg_list, &cset->tasks);
|
|
get_css_set(cset);
|
|
}
|
|
up_write(&css_set_rwsem);
|
|
}
|
|
|
|
/*
|
|
* Call ss->fork(). This must happen after @child is linked on
|
|
* css_set; otherwise, @child might change state between ->fork()
|
|
* and addition to css_set.
|
|
*/
|
|
for_each_subsys_which(ss, i, &have_fork_callback)
|
|
ss->fork(child, subsys_canfork_priv(old_ss_priv, i));
|
|
}
|
|
|
|
/**
|
|
* cgroup_exit - detach cgroup from exiting task
|
|
* @tsk: pointer to task_struct of exiting process
|
|
*
|
|
* Description: Detach cgroup from @tsk and release it.
|
|
*
|
|
* Note that cgroups marked notify_on_release force every task in
|
|
* them to take the global cgroup_mutex mutex when exiting.
|
|
* This could impact scaling on very large systems. Be reluctant to
|
|
* use notify_on_release cgroups where very high task exit scaling
|
|
* is required on large systems.
|
|
*
|
|
* We set the exiting tasks cgroup to the root cgroup (top_cgroup). We
|
|
* call cgroup_exit() while the task is still competent to handle
|
|
* notify_on_release(), then leave the task attached to the root cgroup in
|
|
* each hierarchy for the remainder of its exit. No need to bother with
|
|
* init_css_set refcnting. init_css_set never goes away and we can't race
|
|
* with migration path - PF_EXITING is visible to migration path.
|
|
*/
|
|
void cgroup_exit(struct task_struct *tsk)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
struct css_set *cset;
|
|
bool put_cset = false;
|
|
int i;
|
|
|
|
/*
|
|
* Unlink from @tsk from its css_set. As migration path can't race
|
|
* with us, we can check cg_list without grabbing css_set_rwsem.
|
|
*/
|
|
if (!list_empty(&tsk->cg_list)) {
|
|
down_write(&css_set_rwsem);
|
|
list_del_init(&tsk->cg_list);
|
|
up_write(&css_set_rwsem);
|
|
put_cset = true;
|
|
}
|
|
|
|
/* Reassign the task to the init_css_set. */
|
|
cset = task_css_set(tsk);
|
|
RCU_INIT_POINTER(tsk->cgroups, &init_css_set);
|
|
|
|
/* see cgroup_post_fork() for details */
|
|
for_each_subsys_which(ss, i, &have_exit_callback) {
|
|
struct cgroup_subsys_state *old_css = cset->subsys[i];
|
|
struct cgroup_subsys_state *css = task_css(tsk, i);
|
|
|
|
ss->exit(css, old_css, tsk);
|
|
}
|
|
|
|
if (put_cset)
|
|
put_css_set(cset);
|
|
}
|
|
|
|
static void check_for_release(struct cgroup *cgrp)
|
|
{
|
|
if (notify_on_release(cgrp) && !cgroup_has_tasks(cgrp) &&
|
|
!css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
|
|
schedule_work(&cgrp->release_agent_work);
|
|
}
|
|
|
|
/*
|
|
* Notify userspace when a cgroup is released, by running the
|
|
* configured release agent with the name of the cgroup (path
|
|
* relative to the root of cgroup file system) as the argument.
|
|
*
|
|
* Most likely, this user command will try to rmdir this cgroup.
|
|
*
|
|
* This races with the possibility that some other task will be
|
|
* attached to this cgroup before it is removed, or that some other
|
|
* user task will 'mkdir' a child cgroup of this cgroup. That's ok.
|
|
* The presumed 'rmdir' will fail quietly if this cgroup is no longer
|
|
* unused, and this cgroup will be reprieved from its death sentence,
|
|
* to continue to serve a useful existence. Next time it's released,
|
|
* we will get notified again, if it still has 'notify_on_release' set.
|
|
*
|
|
* The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
|
|
* means only wait until the task is successfully execve()'d. The
|
|
* separate release agent task is forked by call_usermodehelper(),
|
|
* then control in this thread returns here, without waiting for the
|
|
* release agent task. We don't bother to wait because the caller of
|
|
* this routine has no use for the exit status of the release agent
|
|
* task, so no sense holding our caller up for that.
|
|
*/
|
|
static void cgroup_release_agent(struct work_struct *work)
|
|
{
|
|
struct cgroup *cgrp =
|
|
container_of(work, struct cgroup, release_agent_work);
|
|
char *pathbuf = NULL, *agentbuf = NULL, *path;
|
|
char *argv[3], *envp[3];
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
|
|
agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
|
|
if (!pathbuf || !agentbuf)
|
|
goto out;
|
|
|
|
path = cgroup_path(cgrp, pathbuf, PATH_MAX);
|
|
if (!path)
|
|
goto out;
|
|
|
|
argv[0] = agentbuf;
|
|
argv[1] = path;
|
|
argv[2] = NULL;
|
|
|
|
/* minimal command environment */
|
|
envp[0] = "HOME=/";
|
|
envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
|
|
envp[2] = NULL;
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
|
|
goto out_free;
|
|
out:
|
|
mutex_unlock(&cgroup_mutex);
|
|
out_free:
|
|
kfree(agentbuf);
|
|
kfree(pathbuf);
|
|
}
|
|
|
|
static int __init cgroup_disable(char *str)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
char *token;
|
|
int i;
|
|
|
|
while ((token = strsep(&str, ",")) != NULL) {
|
|
if (!*token)
|
|
continue;
|
|
|
|
for_each_subsys(ss, i) {
|
|
if (strcmp(token, ss->name) &&
|
|
strcmp(token, ss->legacy_name))
|
|
continue;
|
|
|
|
static_branch_disable(cgroup_subsys_enabled_key[i]);
|
|
printk(KERN_INFO "Disabling %s control group subsystem\n",
|
|
ss->name);
|
|
break;
|
|
}
|
|
}
|
|
return 1;
|
|
}
|
|
__setup("cgroup_disable=", cgroup_disable);
|
|
|
|
static int __init cgroup_set_legacy_files_on_dfl(char *str)
|
|
{
|
|
printk("cgroup: using legacy files on the default hierarchy\n");
|
|
cgroup_legacy_files_on_dfl = true;
|
|
return 0;
|
|
}
|
|
__setup("cgroup__DEVEL__legacy_files_on_dfl", cgroup_set_legacy_files_on_dfl);
|
|
|
|
/**
|
|
* css_tryget_online_from_dir - get corresponding css from a cgroup dentry
|
|
* @dentry: directory dentry of interest
|
|
* @ss: subsystem of interest
|
|
*
|
|
* If @dentry is a directory for a cgroup which has @ss enabled on it, try
|
|
* to get the corresponding css and return it. If such css doesn't exist
|
|
* or can't be pinned, an ERR_PTR value is returned.
|
|
*/
|
|
struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
|
|
struct cgroup_subsys *ss)
|
|
{
|
|
struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
|
|
struct cgroup_subsys_state *css = NULL;
|
|
struct cgroup *cgrp;
|
|
|
|
/* is @dentry a cgroup dir? */
|
|
if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
|
|
kernfs_type(kn) != KERNFS_DIR)
|
|
return ERR_PTR(-EBADF);
|
|
|
|
rcu_read_lock();
|
|
|
|
/*
|
|
* This path doesn't originate from kernfs and @kn could already
|
|
* have been or be removed at any point. @kn->priv is RCU
|
|
* protected for this access. See css_release_work_fn() for details.
|
|
*/
|
|
cgrp = rcu_dereference(kn->priv);
|
|
if (cgrp)
|
|
css = cgroup_css(cgrp, ss);
|
|
|
|
if (!css || !css_tryget_online(css))
|
|
css = ERR_PTR(-ENOENT);
|
|
|
|
rcu_read_unlock();
|
|
return css;
|
|
}
|
|
|
|
/**
|
|
* css_from_id - lookup css by id
|
|
* @id: the cgroup id
|
|
* @ss: cgroup subsys to be looked into
|
|
*
|
|
* Returns the css if there's valid one with @id, otherwise returns NULL.
|
|
* Should be called under rcu_read_lock().
|
|
*/
|
|
struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss)
|
|
{
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
return id > 0 ? idr_find(&ss->css_idr, id) : NULL;
|
|
}
|
|
|
|
#ifdef CONFIG_CGROUP_DEBUG
|
|
static struct cgroup_subsys_state *
|
|
debug_css_alloc(struct cgroup_subsys_state *parent_css)
|
|
{
|
|
struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
|
|
|
|
if (!css)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
return css;
|
|
}
|
|
|
|
static void debug_css_free(struct cgroup_subsys_state *css)
|
|
{
|
|
kfree(css);
|
|
}
|
|
|
|
static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
return cgroup_task_count(css->cgroup);
|
|
}
|
|
|
|
static u64 current_css_set_read(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
return (u64)(unsigned long)current->cgroups;
|
|
}
|
|
|
|
static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
u64 count;
|
|
|
|
rcu_read_lock();
|
|
count = atomic_read(&task_css_set(current)->refcount);
|
|
rcu_read_unlock();
|
|
return count;
|
|
}
|
|
|
|
static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
|
|
{
|
|
struct cgrp_cset_link *link;
|
|
struct css_set *cset;
|
|
char *name_buf;
|
|
|
|
name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
|
|
if (!name_buf)
|
|
return -ENOMEM;
|
|
|
|
down_read(&css_set_rwsem);
|
|
rcu_read_lock();
|
|
cset = rcu_dereference(current->cgroups);
|
|
list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
|
|
struct cgroup *c = link->cgrp;
|
|
|
|
cgroup_name(c, name_buf, NAME_MAX + 1);
|
|
seq_printf(seq, "Root %d group %s\n",
|
|
c->root->hierarchy_id, name_buf);
|
|
}
|
|
rcu_read_unlock();
|
|
up_read(&css_set_rwsem);
|
|
kfree(name_buf);
|
|
return 0;
|
|
}
|
|
|
|
#define MAX_TASKS_SHOWN_PER_CSS 25
|
|
static int cgroup_css_links_read(struct seq_file *seq, void *v)
|
|
{
|
|
struct cgroup_subsys_state *css = seq_css(seq);
|
|
struct cgrp_cset_link *link;
|
|
|
|
down_read(&css_set_rwsem);
|
|
list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
|
|
struct css_set *cset = link->cset;
|
|
struct task_struct *task;
|
|
int count = 0;
|
|
|
|
seq_printf(seq, "css_set %p\n", cset);
|
|
|
|
list_for_each_entry(task, &cset->tasks, cg_list) {
|
|
if (count++ > MAX_TASKS_SHOWN_PER_CSS)
|
|
goto overflow;
|
|
seq_printf(seq, " task %d\n", task_pid_vnr(task));
|
|
}
|
|
|
|
list_for_each_entry(task, &cset->mg_tasks, cg_list) {
|
|
if (count++ > MAX_TASKS_SHOWN_PER_CSS)
|
|
goto overflow;
|
|
seq_printf(seq, " task %d\n", task_pid_vnr(task));
|
|
}
|
|
continue;
|
|
overflow:
|
|
seq_puts(seq, " ...\n");
|
|
}
|
|
up_read(&css_set_rwsem);
|
|
return 0;
|
|
}
|
|
|
|
static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
|
|
{
|
|
return (!cgroup_has_tasks(css->cgroup) &&
|
|
!css_has_online_children(&css->cgroup->self));
|
|
}
|
|
|
|
static struct cftype debug_files[] = {
|
|
{
|
|
.name = "taskcount",
|
|
.read_u64 = debug_taskcount_read,
|
|
},
|
|
|
|
{
|
|
.name = "current_css_set",
|
|
.read_u64 = current_css_set_read,
|
|
},
|
|
|
|
{
|
|
.name = "current_css_set_refcount",
|
|
.read_u64 = current_css_set_refcount_read,
|
|
},
|
|
|
|
{
|
|
.name = "current_css_set_cg_links",
|
|
.seq_show = current_css_set_cg_links_read,
|
|
},
|
|
|
|
{
|
|
.name = "cgroup_css_links",
|
|
.seq_show = cgroup_css_links_read,
|
|
},
|
|
|
|
{
|
|
.name = "releasable",
|
|
.read_u64 = releasable_read,
|
|
},
|
|
|
|
{ } /* terminate */
|
|
};
|
|
|
|
struct cgroup_subsys debug_cgrp_subsys = {
|
|
.css_alloc = debug_css_alloc,
|
|
.css_free = debug_css_free,
|
|
.legacy_cftypes = debug_files,
|
|
};
|
|
#endif /* CONFIG_CGROUP_DEBUG */
|