From: Tejun Heo <tj@kernel.org>
Date: Mon, 21 Nov 2011 20:32:24 +0000 (-0800)
Subject: freezer: test freezable conditions while holding freezer_lock
X-Git-Tag: v3.3-rc1~148^2~24^2~14
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=85f1d476653f52c97ca75466b2494e67c1cbd25d;p=pandora-kernel.git

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>
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