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Tejun Heo 96d365e0b8 cgroup: make css_set_lock a rwsem and rename it to css_set_rwsem 
Currently there are two ways to walk tasks of a cgroup -
css_task_iter_start/next/end() and css_scan_tasks().  The latter
builds on the former but allows blocking while iterating.
Unfortunately, the way css_scan_tasks() is implemented is rather
nasty, it uses a priority heap of pointers to extract some number of
tasks in task creation order and loops over them invoking the callback
and repeats that until it reaches the end.  It requires either
preallocated heap or may fail under memory pressure, while unlikely to
be problematic, the complexity is O(N^2), and in general just nasty.

We're gonna convert all css_scan_users() to
css_task_iter_start/next/end() and remove css_scan_users().  As
css_scan_tasks() users may block, let's convert css_set_lock to a
rwsem so that tasks can block during css_task_iter_*() is in progress.

While this does increase the chance of possible deadlock scenarios,
given the current usage, the probability is relatively low, and even
if that happens, the right thing to do is updating the iteration in
the similar way to css iterators so that it can handle blocking.

Most conversions are trivial; however, task_cgroup_path() now expects
to be called with css_set_rwsem locked instead of locking itself.
This is because the function is called with RCU read lock held and
rwsem locking should nest outside RCU read lock.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
 		2014-02-13 06:58:40 -05:00
..
cpu sched/preempt: Fix up missed PREEMPT_NEED_RESCHED folding 2014-01-13 17:38:55 +01:00
debug kgdb/kdb: Fix no KDB config problem 2014-01-25 08:55:09 +01:00
events cgroup: improve css_from_dir() into css_tryget_from_dir() 2014-02-11 11:52:47 -05:00
gcov gcov: reuse kbasename helper 2013-11-13 12:09:34 +09:00
irq Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-12-02 10:15:39 -08:00
locking Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-01-20 10:42:08 -08:00
power arm, pm, vmpressure: add missing slab.h includes 2014-02-03 13:24:01 -05:00
printk printk: flush conflicting continuation line 2014-01-23 16:36:56 -08:00
rcu Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-01-28 08:38:04 -08:00
sched cgroup: remove cgroup->name 2014-02-12 09:29:50 -05:00
time Merge branch 'timers/core' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/urgent 2014-01-25 08:27:26 +01:00
trace Merge branch 'for-3.14/core' of git://git.kernel.dk/linux-block 2014-01-30 11:19:05 -08:00
.gitignore Ignore generated file kernel/x509_certificate_list 2013-12-10 18:21:34 +00:00
Kconfig.freezer
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Kconfig.hz kernel: remove CONFIG_USE_GENERIC_SMP_HELPERS 2013-11-15 09:32:22 +09:00
Kconfig.locks locking: Fix copy/paste errors of "ARCH_INLINE_*_UNLOCK_BH" 2013-05-28 08:50:00 +02:00
Kconfig.preempt
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Makefile KEYS: Remove files generated when SYSTEM_TRUSTED_KEYRING=y 2013-12-13 15:59:11 +00:00
acct.c fs: Fix hang with BSD accounting on frozen filesystem 2013-05-04 14:57:58 -04:00
async.c async: rename and redefine async_func_ptr 2013-03-12 13:59:14 -07:00
audit.c audit: fix location of __net_initdata for audit_net_ops 2014-01-17 17:14:32 -05:00
audit.h audit: Convert int limit uses to u32 2014-01-14 14:54:00 -05:00
audit_tree.c fsnotify: remove pointless NULL initializers 2014-01-21 16:19:41 -08:00
audit_watch.c fsnotify: remove pointless NULL initializers 2014-01-21 16:19:41 -08:00
auditfilter.c audit: log on errors from filter user rules 2014-01-13 22:32:31 -05:00
auditsc.c audit: fix dangling keywords in audit_log_set_loginuid() output 2014-01-13 22:32:38 -05:00
backtracetest.c
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bounds.c mm: do not allocate page->ptl dynamically, if spinlock_t fits to long 2013-12-20 12:25:45 -08:00
capability.c audit: Simplify and correct audit_log_capset 2014-01-13 22:26:48 -05:00
cgroup.c cgroup: make css_set_lock a rwsem and rename it to css_set_rwsem 2014-02-13 06:58:40 -05:00
cgroup_freezer.c cgroup: clean up cgroup_subsys names and initialization 2014-02-08 10:36:58 -05:00
compat.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal 2013-05-01 07:21:43 -07:00
configs.c proc: Supply PDE attribute setting accessor functions 2013-05-01 17:29:18 -04:00
context_tracking.c context_tracking: Wrap static key check into more intuitive function name 2013-12-02 20:43:14 +01:00
cpu.c Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-11-14 16:55:11 +09:00
cpu_pm.c
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cpuset.c cgroup: implement cgroup_has_tasks() and unexport cgroup_task_count() 2014-02-13 06:58:39 -05:00
crash_dump.c
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cred.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2012-12-18 10:55:28 -08:00
delayacct.c kernel/delayacct.c: remove redundant checking in __delayacct_add_tsk() 2013-11-13 12:09:12 +09:00
dma.c
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elfcore.c switch elf_core_write_extra_phdrs() to dump_emit() 2013-11-09 00:16:23 -05:00
exec_domain.c
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exit.c introduce for_each_thread() to replace the buggy while_each_thread() 2014-01-21 16:19:46 -08:00
extable.c kernel/extable: fix address-checks for core_kernel and init areas 2013-11-28 09:49:41 -08:00
fork.c exec: kill task_struct->did_exec 2014-01-23 16:37:02 -08:00
freezer.c libata, freezer: avoid block device removal while system is frozen 2013-12-19 13:50:32 -05:00
futex.c Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-01-20 10:42:08 -08:00
futex_compat.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal 2013-02-23 18:50:11 -08:00
groups.c userns: Kill nsown_capable it makes the wrong thing easy 2013-08-30 23:44:11 -07:00
hrtimer.c sched/deadline: Add SCHED_DEADLINE structures & implementation 2014-01-13 13:41:06 +01:00
hung_task.c hung_task: Display every hung task warning 2014-01-25 12:13:33 +01:00
irq_work.c Merge branch 'nohz/printk-v8' into irq/core 2013-02-05 00:48:46 +01:00
itimer.c
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jump_label.c static_key: WARN on usage before jump_label_init was called 2013-10-19 19:45:35 -04:00
kallsyms.c kernel: kallsyms: memory override issue, need check destination buffer length 2013-04-15 15:17:26 +09:30
kcmp.c kcmp: include linux/ptrace.h 2012-12-20 17:40:19 -08:00
kexec.c kernel/kexec.c: use vscnprintf() instead of vsnprintf() in vmcoreinfo_append_str() 2014-01-27 21:02:40 -08:00
kmod.c kernel/kmod.c: check for NULL in call_usermodehelper_exec() 2013-09-30 14:31:02 -07:00
kprobes.c kprobes: use KSYM_NAME_LEN to size identifier buffers 2013-11-13 12:09:26 +09:00
ksysfs.c kdump: fix exported size of vmcoreinfo note 2014-01-23 16:37:03 -08:00
kthread.c kthread: make kthread_create() killable 2013-11-13 12:08:59 +09:00
latencytop.c
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module-internal.h KEYS: Separate the kernel signature checking keyring from module signing 2013-09-25 17:17:01 +01:00
module.c module: Add missing newline in printk call. 2014-01-21 09:59:16 +10:30
module_signing.c keys: change asymmetric keys to use common hash definitions 2013-10-25 17:15:18 -04:00
notifier.c
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nsproxy.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2013-09-07 14:35:32 -07:00
padata.c padata: Fix wrong usage of rcu_dereference() 2013-12-05 21:28:42 +08:00
panic.c panic: Make panic_timeout configurable 2013-11-26 12:12:26 +01:00
params.c params: improve standard definitions 2013-12-04 14:09:46 +10:30
pid.c pidns: fix free_pid() to handle the first fork failure 2013-09-30 14:31:03 -07:00
pid_namespace.c pid_namespace: make freeing struct pid_namespace rcu-delayed 2013-10-24 23:43:29 -04:00
posix-cpu-timers.c posix-timers: Convert abuses of BUG_ON to WARN_ON 2013-12-09 16:56:29 +01:00
posix-timers.c posix-timers: Remove unused variable 2013-04-18 12:51:19 +02:00
profile.c kernel: delete __cpuinit usage from all core kernel files 2013-07-14 19:36:59 -04:00
ptrace.c exec/ptrace: fix get_dumpable() incorrect tests 2013-11-13 12:09:33 +09:00
range.c range: Do not add new blank slot with add_range_with_merge 2013-06-18 11:32:10 -05:00
reboot.c kexec: migrate to reboot cpu 2013-12-18 19:04:50 -08:00
relay.c kernel: delete __cpuinit usage from all core kernel files 2013-07-14 19:36:59 -04:00
res_counter.c memcg: reduce function dereference 2013-09-12 15:38:02 -07:00
resource.c kernel/resource.c: remove the unneeded assignment in function __find_resource 2013-07-03 16:08:06 -07:00
seccomp.c seccomp: allow BPF_XOR based ALU instructions. 2013-03-26 11:07:19 +11:00
signal.c kernel/signal.c: change do_signal_stop/do_sigaction to use while_each_thread() 2014-01-23 16:37:02 -08:00
smp.c kernel/smp.c: remove cpumask_ipi 2014-01-30 16:56:54 -08:00
smpboot.c kernel: delete __cpuinit usage from all core kernel files 2013-07-14 19:36:59 -04:00
smpboot.h
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softirq.c Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-01-31 09:02:51 -08:00
stacktrace.c
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stop_machine.c stop_machine: Fix race between stop_two_cpus() and stop_cpus() 2013-11-11 12:43:38 +01:00
sys.c kernel/sys.c: k_getrusage() can use while_each_thread() 2014-01-23 16:37:02 -08:00
sys_ni.c unify compat fanotify_mark(2), switch to COMPAT_SYSCALL_DEFINE 2013-05-09 13:46:38 -04:00
sysctl.c Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-01-31 08:59:46 -08:00
sysctl_binary.c kernel/sysctl_binary.c: use scnprintf() instead of snprintf() 2013-11-13 12:09:33 +09:00
system_certificates.S KEYS: correct alignment of system_certificate_list content in assembly file 2013-12-10 18:25:28 +00:00
system_keyring.c KEYS: correct alignment of system_certificate_list content in assembly file 2013-12-10 18:25:28 +00:00
task_work.c task_work: documentation 2013-09-11 15:58:27 -07:00
taskstats.c genetlink: only pass array to genl_register_family_with_ops() 2013-11-19 16:39:05 -05:00
test_kprobes.c kernel/: rename random32() to prandom_u32() 2013-04-29 18:28:42 -07:00
time.c sched: Rename sched.c as sched/core.c in comments and Documentation 2013-06-19 12:58:42 +02:00
timeconst.bc kernel: Replace timeconst.pl with a bc script 2013-02-16 23:17:25 +01:00
timer.c timer: Convert kmalloc_node(...GFP_ZERO...) to kzalloc_node(...) 2013-11-19 14:59:50 +01:00
tracepoint.c Tracing updates for Linux 3.10 2013-04-29 13:55:38 -07:00
tsacct.c cputime: Use accessors to read task cputime stats 2013-01-27 19:23:31 +01:00
uid16.c userns: Kill nsown_capable it makes the wrong thing easy 2013-08-30 23:44:11 -07:00
up.c kernel: provide a __smp_call_function_single stub for !CONFIG_SMP 2013-11-15 09:32:22 +09:00
user-return-notifier.c hlist: drop the node parameter from iterators 2013-02-27 19:10:24 -08:00
user.c KEYS: fix uninitialized persistent_keyring_register_sem 2013-12-13 15:59:11 +00:00
user_namespace.c KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches 2013-09-24 10:35:19 +01:00
utsname.c userns: Kill nsown_capable it makes the wrong thing easy 2013-08-30 23:44:11 -07:00
utsname_sysctl.c kernel/utsname_sysctl.c: put get/get_uts() into CONFIG_PROC_SYSCTL code block 2013-02-27 19:10:22 -08:00
watchdog.c watchdog: update watchdog_thresh properly 2013-09-24 17:00:25 -07:00
workqueue.c Merge branch 'for-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2014-01-21 17:46:31 -08:00
workqueue_internal.h sched: Rename sched.c as sched/core.c in comments and Documentation 2013-06-19 12:58:42 +02:00