linux/fs/sysfs/bin.c

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/*
* fs/sysfs/bin.c - sysfs binary file implementation
*
* Copyright (c) 2003 Patrick Mochel
* Copyright (c) 2003 Matthew Wilcox
* Copyright (c) 2004 Silicon Graphics, Inc.
* Copyright (c) 2007 SUSE Linux Products GmbH
* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
*
* This file is released under the GPLv2.
*
* Please see Documentation/filesystems/sysfs.txt for more information.
*/
#undef DEBUG
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/mm.h>
#include <asm/uaccess.h>
#include "sysfs.h"
/*
* There's one bin_buffer for each open file.
*
* filp->private_data points to bin_buffer and
* sysfs_dirent->s_bin_attr.buffers points to a the bin_buffer s
* sysfs_dirent->s_bin_attr.buffers is protected by sysfs_bin_lock
*/
static DEFINE_MUTEX(sysfs_bin_lock);
struct bin_buffer {
struct mutex mutex;
void *buffer;
int mmapped;
const struct vm_operations_struct *vm_ops;
struct file *file;
struct hlist_node list;
};
static int
fill_read(struct file *file, char *buffer, loff_t off, size_t count)
{
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
int rc;
/* need attr_sd for attr, its parent for kobj */
if (!sysfs_get_active(attr_sd))
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
return -ENODEV;
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
rc = -EIO;
if (attr->read)
rc = attr->read(file, kobj, attr, buffer, off, count);
sysfs_put_active(attr_sd);
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
return rc;
}
static ssize_t
read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
{
struct bin_buffer *bb = file->private_data;
int size = file->f_path.dentry->d_inode->i_size;
loff_t offs = *off;
int count = min_t(size_t, bytes, PAGE_SIZE);
sysfs: fix deadlock On Thu, Sep 11, 2008 at 10:27:10AM +0200, Ingo Molnar wrote: > and it's working fine on most boxes. One testbox found this new locking > scenario: > > PM: Adding info for No Bus:vcsa7 > EDAC DEBUG: MC0: i82860_check() > > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.27-rc6-tip #1 > ------------------------------------------------------- > X/4873 is trying to acquire lock: > (&bb->mutex){--..}, at: [<c020ba20>] mmap+0x40/0xa0 > > but task is already holding lock: > (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #1 (&mm->mmap_sem){----}: > [<c017dc96>] validate_chain+0xa96/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c01aa8fb>] might_fault+0x6b/0x90 > [<c040b618>] copy_to_user+0x38/0x60 > [<c020bcfb>] read+0xfb/0x170 > [<c01c09a5>] vfs_read+0x95/0x110 > [<c01c1443>] sys_pread64+0x63/0x80 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > -> #0 (&bb->mutex){--..}: > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > other info that might help us debug this: > > 1 lock held by X/4873: > #0: (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > stack backtrace: > Pid: 4873, comm: X Not tainted 2.6.27-rc6-tip #1 > [<c017cd09>] print_circular_bug_tail+0x79/0xc0 > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017a5b5>] ? trace_hardirqs_off_caller+0x15/0xb0 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01afb88>] ? arch_get_unmapped_area_topdown+0xf8/0x160 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<c0120000>] ? __switch_to+0x130/0x220 > ======================= > evbug.c: Event. Dev: input3, Type: 20, Code: 0, Value: 500 > warning: `sudo' uses deprecated v2 capabilities in a way that may be insecure. > > i've attached the config. > > at first sight it looks like a genuine bug in fs/sysfs/bin.c? Yes, it is a real bug by the looks. bin.c takes bb->mutex under mmap_sem when it is mmapped, and then does its copy_*_user under bb->mutex too. Here is a basic fix for the sysfs lor. From: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-09-12 11:24:11 +02:00
char *temp;
if (!bytes)
return 0;
if (size) {
if (offs > size)
return 0;
if (offs + count > size)
count = size - offs;
}
sysfs: fix deadlock On Thu, Sep 11, 2008 at 10:27:10AM +0200, Ingo Molnar wrote: > and it's working fine on most boxes. One testbox found this new locking > scenario: > > PM: Adding info for No Bus:vcsa7 > EDAC DEBUG: MC0: i82860_check() > > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.27-rc6-tip #1 > ------------------------------------------------------- > X/4873 is trying to acquire lock: > (&bb->mutex){--..}, at: [<c020ba20>] mmap+0x40/0xa0 > > but task is already holding lock: > (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #1 (&mm->mmap_sem){----}: > [<c017dc96>] validate_chain+0xa96/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c01aa8fb>] might_fault+0x6b/0x90 > [<c040b618>] copy_to_user+0x38/0x60 > [<c020bcfb>] read+0xfb/0x170 > [<c01c09a5>] vfs_read+0x95/0x110 > [<c01c1443>] sys_pread64+0x63/0x80 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > -> #0 (&bb->mutex){--..}: > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > other info that might help us debug this: > > 1 lock held by X/4873: > #0: (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > stack backtrace: > Pid: 4873, comm: X Not tainted 2.6.27-rc6-tip #1 > [<c017cd09>] print_circular_bug_tail+0x79/0xc0 > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017a5b5>] ? trace_hardirqs_off_caller+0x15/0xb0 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01afb88>] ? arch_get_unmapped_area_topdown+0xf8/0x160 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<c0120000>] ? __switch_to+0x130/0x220 > ======================= > evbug.c: Event. Dev: input3, Type: 20, Code: 0, Value: 500 > warning: `sudo' uses deprecated v2 capabilities in a way that may be insecure. > > i've attached the config. > > at first sight it looks like a genuine bug in fs/sysfs/bin.c? Yes, it is a real bug by the looks. bin.c takes bb->mutex under mmap_sem when it is mmapped, and then does its copy_*_user under bb->mutex too. Here is a basic fix for the sysfs lor. From: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-09-12 11:24:11 +02:00
temp = kmalloc(count, GFP_KERNEL);
if (!temp)
return -ENOMEM;
mutex_lock(&bb->mutex);
count = fill_read(file, bb->buffer, offs, count);
sysfs: fix deadlock On Thu, Sep 11, 2008 at 10:27:10AM +0200, Ingo Molnar wrote: > and it's working fine on most boxes. One testbox found this new locking > scenario: > > PM: Adding info for No Bus:vcsa7 > EDAC DEBUG: MC0: i82860_check() > > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.27-rc6-tip #1 > ------------------------------------------------------- > X/4873 is trying to acquire lock: > (&bb->mutex){--..}, at: [<c020ba20>] mmap+0x40/0xa0 > > but task is already holding lock: > (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #1 (&mm->mmap_sem){----}: > [<c017dc96>] validate_chain+0xa96/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c01aa8fb>] might_fault+0x6b/0x90 > [<c040b618>] copy_to_user+0x38/0x60 > [<c020bcfb>] read+0xfb/0x170 > [<c01c09a5>] vfs_read+0x95/0x110 > [<c01c1443>] sys_pread64+0x63/0x80 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > -> #0 (&bb->mutex){--..}: > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > other info that might help us debug this: > > 1 lock held by X/4873: > #0: (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > stack backtrace: > Pid: 4873, comm: X Not tainted 2.6.27-rc6-tip #1 > [<c017cd09>] print_circular_bug_tail+0x79/0xc0 > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017a5b5>] ? trace_hardirqs_off_caller+0x15/0xb0 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01afb88>] ? arch_get_unmapped_area_topdown+0xf8/0x160 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<c0120000>] ? __switch_to+0x130/0x220 > ======================= > evbug.c: Event. Dev: input3, Type: 20, Code: 0, Value: 500 > warning: `sudo' uses deprecated v2 capabilities in a way that may be insecure. > > i've attached the config. > > at first sight it looks like a genuine bug in fs/sysfs/bin.c? Yes, it is a real bug by the looks. bin.c takes bb->mutex under mmap_sem when it is mmapped, and then does its copy_*_user under bb->mutex too. Here is a basic fix for the sysfs lor. From: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-09-12 11:24:11 +02:00
if (count < 0) {
mutex_unlock(&bb->mutex);
goto out_free;
}
sysfs: fix deadlock On Thu, Sep 11, 2008 at 10:27:10AM +0200, Ingo Molnar wrote: > and it's working fine on most boxes. One testbox found this new locking > scenario: > > PM: Adding info for No Bus:vcsa7 > EDAC DEBUG: MC0: i82860_check() > > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.27-rc6-tip #1 > ------------------------------------------------------- > X/4873 is trying to acquire lock: > (&bb->mutex){--..}, at: [<c020ba20>] mmap+0x40/0xa0 > > but task is already holding lock: > (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #1 (&mm->mmap_sem){----}: > [<c017dc96>] validate_chain+0xa96/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c01aa8fb>] might_fault+0x6b/0x90 > [<c040b618>] copy_to_user+0x38/0x60 > [<c020bcfb>] read+0xfb/0x170 > [<c01c09a5>] vfs_read+0x95/0x110 > [<c01c1443>] sys_pread64+0x63/0x80 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > -> #0 (&bb->mutex){--..}: > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > other info that might help us debug this: > > 1 lock held by X/4873: > #0: (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > stack backtrace: > Pid: 4873, comm: X Not tainted 2.6.27-rc6-tip #1 > [<c017cd09>] print_circular_bug_tail+0x79/0xc0 > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017a5b5>] ? trace_hardirqs_off_caller+0x15/0xb0 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01afb88>] ? arch_get_unmapped_area_topdown+0xf8/0x160 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<c0120000>] ? __switch_to+0x130/0x220 > ======================= > evbug.c: Event. Dev: input3, Type: 20, Code: 0, Value: 500 > warning: `sudo' uses deprecated v2 capabilities in a way that may be insecure. > > i've attached the config. > > at first sight it looks like a genuine bug in fs/sysfs/bin.c? Yes, it is a real bug by the looks. bin.c takes bb->mutex under mmap_sem when it is mmapped, and then does its copy_*_user under bb->mutex too. Here is a basic fix for the sysfs lor. From: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-09-12 11:24:11 +02:00
memcpy(temp, bb->buffer, count);
mutex_unlock(&bb->mutex);
if (copy_to_user(userbuf, temp, count)) {
count = -EFAULT;
sysfs: fix deadlock On Thu, Sep 11, 2008 at 10:27:10AM +0200, Ingo Molnar wrote: > and it's working fine on most boxes. One testbox found this new locking > scenario: > > PM: Adding info for No Bus:vcsa7 > EDAC DEBUG: MC0: i82860_check() > > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.27-rc6-tip #1 > ------------------------------------------------------- > X/4873 is trying to acquire lock: > (&bb->mutex){--..}, at: [<c020ba20>] mmap+0x40/0xa0 > > but task is already holding lock: > (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #1 (&mm->mmap_sem){----}: > [<c017dc96>] validate_chain+0xa96/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c01aa8fb>] might_fault+0x6b/0x90 > [<c040b618>] copy_to_user+0x38/0x60 > [<c020bcfb>] read+0xfb/0x170 > [<c01c09a5>] vfs_read+0x95/0x110 > [<c01c1443>] sys_pread64+0x63/0x80 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > -> #0 (&bb->mutex){--..}: > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > other info that might help us debug this: > > 1 lock held by X/4873: > #0: (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > stack backtrace: > Pid: 4873, comm: X Not tainted 2.6.27-rc6-tip #1 > [<c017cd09>] print_circular_bug_tail+0x79/0xc0 > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017a5b5>] ? trace_hardirqs_off_caller+0x15/0xb0 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01afb88>] ? arch_get_unmapped_area_topdown+0xf8/0x160 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<c0120000>] ? __switch_to+0x130/0x220 > ======================= > evbug.c: Event. Dev: input3, Type: 20, Code: 0, Value: 500 > warning: `sudo' uses deprecated v2 capabilities in a way that may be insecure. > > i've attached the config. > > at first sight it looks like a genuine bug in fs/sysfs/bin.c? Yes, it is a real bug by the looks. bin.c takes bb->mutex under mmap_sem when it is mmapped, and then does its copy_*_user under bb->mutex too. Here is a basic fix for the sysfs lor. From: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-09-12 11:24:11 +02:00
goto out_free;
}
pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);
*off = offs + count;
sysfs: fix deadlock On Thu, Sep 11, 2008 at 10:27:10AM +0200, Ingo Molnar wrote: > and it's working fine on most boxes. One testbox found this new locking > scenario: > > PM: Adding info for No Bus:vcsa7 > EDAC DEBUG: MC0: i82860_check() > > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.27-rc6-tip #1 > ------------------------------------------------------- > X/4873 is trying to acquire lock: > (&bb->mutex){--..}, at: [<c020ba20>] mmap+0x40/0xa0 > > but task is already holding lock: > (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #1 (&mm->mmap_sem){----}: > [<c017dc96>] validate_chain+0xa96/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c01aa8fb>] might_fault+0x6b/0x90 > [<c040b618>] copy_to_user+0x38/0x60 > [<c020bcfb>] read+0xfb/0x170 > [<c01c09a5>] vfs_read+0x95/0x110 > [<c01c1443>] sys_pread64+0x63/0x80 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > -> #0 (&bb->mutex){--..}: > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > other info that might help us debug this: > > 1 lock held by X/4873: > #0: (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > stack backtrace: > Pid: 4873, comm: X Not tainted 2.6.27-rc6-tip #1 > [<c017cd09>] print_circular_bug_tail+0x79/0xc0 > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017a5b5>] ? trace_hardirqs_off_caller+0x15/0xb0 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01afb88>] ? arch_get_unmapped_area_topdown+0xf8/0x160 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<c0120000>] ? __switch_to+0x130/0x220 > ======================= > evbug.c: Event. Dev: input3, Type: 20, Code: 0, Value: 500 > warning: `sudo' uses deprecated v2 capabilities in a way that may be insecure. > > i've attached the config. > > at first sight it looks like a genuine bug in fs/sysfs/bin.c? Yes, it is a real bug by the looks. bin.c takes bb->mutex under mmap_sem when it is mmapped, and then does its copy_*_user under bb->mutex too. Here is a basic fix for the sysfs lor. From: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-09-12 11:24:11 +02:00
out_free:
kfree(temp);
return count;
}
static int
flush_write(struct file *file, char *buffer, loff_t offset, size_t count)
{
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
int rc;
/* need attr_sd for attr, its parent for kobj */
if (!sysfs_get_active(attr_sd))
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
return -ENODEV;
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
rc = -EIO;
if (attr->write)
rc = attr->write(file, kobj, attr, buffer, offset, count);
sysfs_put_active(attr_sd);
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
return rc;
}
static ssize_t write(struct file *file, const char __user *userbuf,
size_t bytes, loff_t *off)
{
struct bin_buffer *bb = file->private_data;
int size = file->f_path.dentry->d_inode->i_size;
loff_t offs = *off;
int count = min_t(size_t, bytes, PAGE_SIZE);
sysfs: fix deadlock On Thu, Sep 11, 2008 at 10:27:10AM +0200, Ingo Molnar wrote: > and it's working fine on most boxes. One testbox found this new locking > scenario: > > PM: Adding info for No Bus:vcsa7 > EDAC DEBUG: MC0: i82860_check() > > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.27-rc6-tip #1 > ------------------------------------------------------- > X/4873 is trying to acquire lock: > (&bb->mutex){--..}, at: [<c020ba20>] mmap+0x40/0xa0 > > but task is already holding lock: > (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #1 (&mm->mmap_sem){----}: > [<c017dc96>] validate_chain+0xa96/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c01aa8fb>] might_fault+0x6b/0x90 > [<c040b618>] copy_to_user+0x38/0x60 > [<c020bcfb>] read+0xfb/0x170 > [<c01c09a5>] vfs_read+0x95/0x110 > [<c01c1443>] sys_pread64+0x63/0x80 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > -> #0 (&bb->mutex){--..}: > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > other info that might help us debug this: > > 1 lock held by X/4873: > #0: (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > stack backtrace: > Pid: 4873, comm: X Not tainted 2.6.27-rc6-tip #1 > [<c017cd09>] print_circular_bug_tail+0x79/0xc0 > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017a5b5>] ? trace_hardirqs_off_caller+0x15/0xb0 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01afb88>] ? arch_get_unmapped_area_topdown+0xf8/0x160 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<c0120000>] ? __switch_to+0x130/0x220 > ======================= > evbug.c: Event. Dev: input3, Type: 20, Code: 0, Value: 500 > warning: `sudo' uses deprecated v2 capabilities in a way that may be insecure. > > i've attached the config. > > at first sight it looks like a genuine bug in fs/sysfs/bin.c? Yes, it is a real bug by the looks. bin.c takes bb->mutex under mmap_sem when it is mmapped, and then does its copy_*_user under bb->mutex too. Here is a basic fix for the sysfs lor. From: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-09-12 11:24:11 +02:00
char *temp;
if (!bytes)
return 0;
if (size) {
if (offs > size)
return 0;
if (offs + count > size)
count = size - offs;
}
temp = memdup_user(userbuf, count);
if (IS_ERR(temp))
return PTR_ERR(temp);
sysfs: fix deadlock On Thu, Sep 11, 2008 at 10:27:10AM +0200, Ingo Molnar wrote: > and it's working fine on most boxes. One testbox found this new locking > scenario: > > PM: Adding info for No Bus:vcsa7 > EDAC DEBUG: MC0: i82860_check() > > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.27-rc6-tip #1 > ------------------------------------------------------- > X/4873 is trying to acquire lock: > (&bb->mutex){--..}, at: [<c020ba20>] mmap+0x40/0xa0 > > but task is already holding lock: > (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #1 (&mm->mmap_sem){----}: > [<c017dc96>] validate_chain+0xa96/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c01aa8fb>] might_fault+0x6b/0x90 > [<c040b618>] copy_to_user+0x38/0x60 > [<c020bcfb>] read+0xfb/0x170 > [<c01c09a5>] vfs_read+0x95/0x110 > [<c01c1443>] sys_pread64+0x63/0x80 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > -> #0 (&bb->mutex){--..}: > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > other info that might help us debug this: > > 1 lock held by X/4873: > #0: (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > stack backtrace: > Pid: 4873, comm: X Not tainted 2.6.27-rc6-tip #1 > [<c017cd09>] print_circular_bug_tail+0x79/0xc0 > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017a5b5>] ? trace_hardirqs_off_caller+0x15/0xb0 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01afb88>] ? arch_get_unmapped_area_topdown+0xf8/0x160 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<c0120000>] ? __switch_to+0x130/0x220 > ======================= > evbug.c: Event. Dev: input3, Type: 20, Code: 0, Value: 500 > warning: `sudo' uses deprecated v2 capabilities in a way that may be insecure. > > i've attached the config. > > at first sight it looks like a genuine bug in fs/sysfs/bin.c? Yes, it is a real bug by the looks. bin.c takes bb->mutex under mmap_sem when it is mmapped, and then does its copy_*_user under bb->mutex too. Here is a basic fix for the sysfs lor. From: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-09-12 11:24:11 +02:00
mutex_lock(&bb->mutex);
memcpy(bb->buffer, temp, count);
count = flush_write(file, bb->buffer, offs, count);
sysfs: fix deadlock On Thu, Sep 11, 2008 at 10:27:10AM +0200, Ingo Molnar wrote: > and it's working fine on most boxes. One testbox found this new locking > scenario: > > PM: Adding info for No Bus:vcsa7 > EDAC DEBUG: MC0: i82860_check() > > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.27-rc6-tip #1 > ------------------------------------------------------- > X/4873 is trying to acquire lock: > (&bb->mutex){--..}, at: [<c020ba20>] mmap+0x40/0xa0 > > but task is already holding lock: > (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #1 (&mm->mmap_sem){----}: > [<c017dc96>] validate_chain+0xa96/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c01aa8fb>] might_fault+0x6b/0x90 > [<c040b618>] copy_to_user+0x38/0x60 > [<c020bcfb>] read+0xfb/0x170 > [<c01c09a5>] vfs_read+0x95/0x110 > [<c01c1443>] sys_pread64+0x63/0x80 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > -> #0 (&bb->mutex){--..}: > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<ffffffff>] 0xffffffff > > other info that might help us debug this: > > 1 lock held by X/4873: > #0: (&mm->mmap_sem){----}, at: [<c0125a1e>] sys_mmap2+0x8e/0xc0 > > stack backtrace: > Pid: 4873, comm: X Not tainted 2.6.27-rc6-tip #1 > [<c017cd09>] print_circular_bug_tail+0x79/0xc0 > [<c017d8b7>] validate_chain+0x6b7/0xf50 > [<c017a5b5>] ? trace_hardirqs_off_caller+0x15/0xb0 > [<c017ef2b>] __lock_acquire+0x2cb/0x5b0 > [<c017f299>] lock_acquire+0x89/0xc0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f2ab>] __mutex_lock_common+0xab/0x3c0 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c0d6f698>] mutex_lock_nested+0x38/0x50 > [<c020ba20>] ? mmap+0x40/0xa0 > [<c020ba20>] mmap+0x40/0xa0 > [<c01b111e>] mmap_region+0x14e/0x450 > [<c01afb88>] ? arch_get_unmapped_area_topdown+0xf8/0x160 > [<c01b170f>] do_mmap_pgoff+0x2ef/0x310 > [<c0125a3d>] sys_mmap2+0xad/0xc0 > [<c012146f>] sysenter_do_call+0x12/0x43 > [<c0120000>] ? __switch_to+0x130/0x220 > ======================= > evbug.c: Event. Dev: input3, Type: 20, Code: 0, Value: 500 > warning: `sudo' uses deprecated v2 capabilities in a way that may be insecure. > > i've attached the config. > > at first sight it looks like a genuine bug in fs/sysfs/bin.c? Yes, it is a real bug by the looks. bin.c takes bb->mutex under mmap_sem when it is mmapped, and then does its copy_*_user under bb->mutex too. Here is a basic fix for the sysfs lor. From: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-09-12 11:24:11 +02:00
mutex_unlock(&bb->mutex);
if (count > 0)
*off = offs + count;
kfree(temp);
return count;
}
static void bin_vma_open(struct vm_area_struct *vma)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
if (!bb->vm_ops)
return;
if (!sysfs_get_active(attr_sd))
return;
if (bb->vm_ops->open)
bb->vm_ops->open(vma);
sysfs_put_active(attr_sd);
}
static int bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
int ret;
if (!bb->vm_ops)
return VM_FAULT_SIGBUS;
if (!sysfs_get_active(attr_sd))
return VM_FAULT_SIGBUS;
ret = VM_FAULT_SIGBUS;
if (bb->vm_ops->fault)
ret = bb->vm_ops->fault(vma, vmf);
sysfs_put_active(attr_sd);
return ret;
}
static int bin_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
int ret;
if (!bb->vm_ops)
return VM_FAULT_SIGBUS;
if (!sysfs_get_active(attr_sd))
return VM_FAULT_SIGBUS;
ret = 0;
if (bb->vm_ops->page_mkwrite)
ret = bb->vm_ops->page_mkwrite(vma, vmf);
sysfs_put_active(attr_sd);
return ret;
}
static int bin_access(struct vm_area_struct *vma, unsigned long addr,
void *buf, int len, int write)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
int ret;
if (!bb->vm_ops)
return -EINVAL;
if (!sysfs_get_active(attr_sd))
return -EINVAL;
ret = -EINVAL;
if (bb->vm_ops->access)
ret = bb->vm_ops->access(vma, addr, buf, len, write);
sysfs_put_active(attr_sd);
return ret;
}
#ifdef CONFIG_NUMA
static int bin_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
int ret;
if (!bb->vm_ops)
return 0;
if (!sysfs_get_active(attr_sd))
return -EINVAL;
ret = 0;
if (bb->vm_ops->set_policy)
ret = bb->vm_ops->set_policy(vma, new);
sysfs_put_active(attr_sd);
return ret;
}
static struct mempolicy *bin_get_policy(struct vm_area_struct *vma,
unsigned long addr)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct mempolicy *pol;
if (!bb->vm_ops)
return vma->vm_policy;
if (!sysfs_get_active(attr_sd))
return vma->vm_policy;
pol = vma->vm_policy;
if (bb->vm_ops->get_policy)
pol = bb->vm_ops->get_policy(vma, addr);
sysfs_put_active(attr_sd);
return pol;
}
static int bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
const nodemask_t *to, unsigned long flags)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
int ret;
if (!bb->vm_ops)
return 0;
if (!sysfs_get_active(attr_sd))
return 0;
ret = 0;
if (bb->vm_ops->migrate)
ret = bb->vm_ops->migrate(vma, from, to, flags);
sysfs_put_active(attr_sd);
return ret;
}
#endif
static const struct vm_operations_struct bin_vm_ops = {
.open = bin_vma_open,
.fault = bin_fault,
.page_mkwrite = bin_page_mkwrite,
.access = bin_access,
#ifdef CONFIG_NUMA
.set_policy = bin_set_policy,
.get_policy = bin_get_policy,
.migrate = bin_migrate,
#endif
};
static int mmap(struct file *file, struct vm_area_struct *vma)
{
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
int rc;
mutex_lock(&bb->mutex);
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
/* need attr_sd for attr, its parent for kobj */
rc = -ENODEV;
if (!sysfs_get_active(attr_sd))
goto out_unlock;
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
rc = -EINVAL;
if (!attr->mmap)
goto out_put;
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
rc = attr->mmap(file, kobj, attr, vma);
if (rc)
goto out_put;
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
/*
* PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
* to satisfy versions of X which crash if the mmap fails: that
* substitutes a new vm_file, and we don't then want bin_vm_ops.
*/
if (vma->vm_file != file)
goto out_put;
rc = -EINVAL;
if (bb->mmapped && bb->vm_ops != vma->vm_ops)
goto out_put;
/*
* It is not possible to successfully wrap close.
* So error if someone is trying to use close.
*/
rc = -EINVAL;
if (vma->vm_ops && vma->vm_ops->close)
goto out_put;
rc = 0;
bb->mmapped = 1;
bb->vm_ops = vma->vm_ops;
vma->vm_ops = &bin_vm_ops;
out_put:
sysfs_put_active(attr_sd);
out_unlock:
mutex_unlock(&bb->mutex);
return rc;
}
static int open(struct inode * inode, struct file * file)
{
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
struct bin_buffer *bb = NULL;
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
int error;
/* binary file operations requires both @sd and its parent */
if (!sysfs_get_active(attr_sd))
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
return -ENODEV;
error = -EACCES;
if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
goto err_out;
if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
goto err_out;
error = -ENOMEM;
bb = kzalloc(sizeof(*bb), GFP_KERNEL);
if (!bb)
goto err_out;
bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!bb->buffer)
goto err_out;
mutex_init(&bb->mutex);
bb->file = file;
file->private_data = bb;
mutex_lock(&sysfs_bin_lock);
hlist_add_head(&bb->list, &attr_sd->s_bin_attr.buffers);
mutex_unlock(&sysfs_bin_lock);
/* open succeeded, put active references */
sysfs_put_active(attr_sd);
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
return 0;
err_out:
sysfs_put_active(attr_sd);
sysfs: implement sysfs_dirent active reference and immediate disconnect sysfs: implement sysfs_dirent active reference and immediate disconnect Opening a sysfs node references its associated kobject, so userland can arbitrarily prolong lifetime of a kobject which complicates lifetime rules in drivers. This patch implements active reference and makes the association between kobject and sysfs immediately breakable. Now each sysfs_dirent has two reference counts - s_count and s_active. s_count is a regular reference count which guarantees that the containing sysfs_dirent is accessible. As long as s_count reference is held, all sysfs internal fields in sysfs_dirent are accessible including s_parent and s_name. The newly added s_active is active reference count. This is acquired by invoking sysfs_get_active() and it's the caller's responsibility to ensure sysfs_dirent itself is accessible (should be holding s_count one way or the other). Dereferencing sysfs_dirent to access objects out of sysfs proper requires active reference. This includes access to the associated kobjects, attributes and ops. The active references can be drained and denied by calling sysfs_deactivate(). All active sysfs_dirents must be deactivated after deletion but before the default reference is dropped. This enables immediate disconnect of sysfs nodes. Once a sysfs_dirent is deleted, it won't access any entity external to sysfs proper. Because attr/bin_attr ops access both the node itself and its parent for kobject, they need to hold active references to both. sysfs_get/put_active_two() helpers are provided to help grabbing both references. Parent's is acquired first and released last. Unlike other operations, mmapped area lingers on after mmap() is finished and the module implement implementing it and kobj need to stay referenced till all the mapped pages are gone. This is accomplished by holding one set of active references to the bin_attr and its parent if there have been any mmap during lifetime of an openfile. The references are dropped when the openfile is released. This change makes sysfs lifetime rules independent from both kobject's and module's. It not only fixes several race conditions caused by sysfs not holding onto the proper module when referencing kobject, but also helps fixing and simplifying lifetime management in driver model and drivers by taking sysfs out of the equation. Please read the following message for more info. http://article.gmane.org/gmane.linux.kernel/510293 Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-13 20:45:16 +02:00
kfree(bb);
return error;
}
static int release(struct inode * inode, struct file * file)
{
struct bin_buffer *bb = file->private_data;
mutex_lock(&sysfs_bin_lock);
hlist_del(&bb->list);
mutex_unlock(&sysfs_bin_lock);
kfree(bb->buffer);
kfree(bb);
return 0;
}
const struct file_operations bin_fops = {
.read = read,
.write = write,
.mmap = mmap,
.llseek = generic_file_llseek,
.open = open,
.release = release,
};
void unmap_bin_file(struct sysfs_dirent *attr_sd)
{
struct bin_buffer *bb;
struct hlist_node *tmp;
if (sysfs_type(attr_sd) != SYSFS_KOBJ_BIN_ATTR)
return;
mutex_lock(&sysfs_bin_lock);
hlist_for_each_entry(bb, tmp, &attr_sd->s_bin_attr.buffers, list) {
struct inode *inode = bb->file->f_path.dentry->d_inode;
unmap_mapping_range(inode->i_mapping, 0, 0, 1);
}
mutex_unlock(&sysfs_bin_lock);
}
/**
* sysfs_create_bin_file - create binary file for object.
* @kobj: object.
* @attr: attribute descriptor.
*/
int sysfs_create_bin_file(struct kobject *kobj,
const struct bin_attribute *attr)
{
BUG_ON(!kobj || !kobj->sd || !attr);
return sysfs_add_file(kobj->sd, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
}
/**
* sysfs_remove_bin_file - remove binary file for object.
* @kobj: object.
* @attr: attribute descriptor.
*/
void sysfs_remove_bin_file(struct kobject *kobj,
const struct bin_attribute *attr)
{
sysfs: Implement sysfs tagged directory support. The problem. When implementing a network namespace I need to be able to have multiple network devices with the same name. Currently this is a problem for /sys/class/net/*, /sys/devices/virtual/net/*, and potentially a few other directories of the form /sys/ ... /net/*. What this patch does is to add an additional tag field to the sysfs dirent structure. For directories that should show different contents depending on the context such as /sys/class/net/, and /sys/devices/virtual/net/ this tag field is used to specify the context in which those directories should be visible. Effectively this is the same as creating multiple distinct directories with the same name but internally to sysfs the result is nicer. I am calling the concept of a single directory that looks like multiple directories all at the same path in the filesystem tagged directories. For the networking namespace the set of directories whose contents I need to filter with tags can depend on the presence or absence of hotplug hardware or which modules are currently loaded. Which means I need a simple race free way to setup those directories as tagged. To achieve a reace free design all tagged directories are created and managed by sysfs itself. Users of this interface: - define a type in the sysfs_tag_type enumeration. - call sysfs_register_ns_types with the type and it's operations - sysfs_exit_ns when an individual tag is no longer valid - Implement mount_ns() which returns the ns of the calling process so we can attach it to a sysfs superblock. - Implement ktype.namespace() which returns the ns of a syfs kobject. Everything else is left up to sysfs and the driver layer. For the network namespace mount_ns and namespace() are essentially one line functions, and look to remain that. Tags are currently represented a const void * pointers as that is both generic, prevides enough information for equality comparisons, and is trivial to create for current users, as it is just the existing namespace pointer. The work needed in sysfs is more extensive. At each directory or symlink creating I need to check if the directory it is being created in is a tagged directory and if so generate the appropriate tag to place on the sysfs_dirent. Likewise at each symlink or directory removal I need to check if the sysfs directory it is being removed from is a tagged directory and if so figure out which tag goes along with the name I am deleting. Currently only directories which hold kobjects, and symlinks are supported. There is not enough information in the current file attribute interfaces to give us anything to discriminate on which makes it useless, and there are no potential users which makes it an uninteresting problem to solve. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Benjamin Thery <benjamin.thery@bull.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-03-30 20:31:26 +02:00
sysfs_hash_and_remove(kobj->sd, NULL, attr->attr.name);
}
EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);