]> git.baikalelectronics.ru Git - kernel.git/commit
freezer: close potential race between refrigerator and thaw_tasks
authorRafael J. Wysocki <rjw@sisk.pl>
Wed, 23 May 2007 20:57:24 +0000 (13:57 -0700)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Thu, 24 May 2007 03:14:10 +0000 (20:14 -0700)
commit1e6f2fba16e0d191556b6a14ad4265e05e805dbb
tree68837483316db1fa08bcb2b444cabae75d31a5b2
parent41e74b5cfdb0b934e6c0f03b3472a50f6c8f8f77
freezer: close potential race between refrigerator and thaw_tasks

If the freezing of tasks fails and a task is preempted in refrigerator()
before calling frozen_process(), then thaw_tasks() may run before this task is
frozen.  In that case the task will freeze and no one will thaw it.

To fix this race we can call freezing(current) in refrigerator() along with
frozen_process(current) under the task_lock() which also should be taken in
the error path of try_to_freeze_tasks() as well as in thaw_process().
Moreover, if thaw_process() additionally clears TIF_FREEZE for tasks that are
not frozen, we can be sure that all tasks are thawed and there are no pending
"freeze" requests after thaw_tasks() has run.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/freezer.h
kernel/power/process.c