freezer: test freezable conditions while holding freezer_lock

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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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This commit is contained in:

Tejun Heo 2011-11-21 12:32:24 -08:00

parent 6907483b4e

commit 85f1d47665

2 changed files with 3 additions and 16 deletions

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3

kernel/freezer.c

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16

kernel/power/process.c

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