tree a1839143272cc4e6593e5d4c97e8a3c39aed08ff
parent 6907483b4e803a20f0b48cc9afa3817420ce61c5
author Tejun Heo <tj@kernel.org> 1321907544 -0800
committer Tejun Heo <tj@kernel.org> 1321907544 -0800

freezer: test freezable conditions while holding freezer_lock

try_to_freeze_tasks() and thaw_processes() use freezable() and
frozen() as preliminary tests before initiating operations on a task.
These are done without any synchronization and hinder with
synchronization cleanup without any real performance benefits.

In try_to_freeze_tasks(), open code self test and move PF_NOFREEZE and
frozen() tests inside freezer_lock in freeze_task().

thaw_processes() can simply drop freezable() test as frozen() test in
__thaw_task() is enough.

Note: This used to be a part of larger patch to fix set_freezable()
      race.  Separated out to satisfy ordering among dependent fixes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>