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authorGautham R Shenoy <ego@in.ibm.com>2007-05-23 13:57:28 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-23 20:14:11 -0700
commit5fcc57f2d5d558056668159f9153bf21d2c53d16 (patch)
treeaa81c453b093f051bf775cd8fb557df9d2f79543 /include
parenta076e4bca2fdabb9e45d86722cc72c0944da5f94 (diff)
downloadop-kernel-dev-5fcc57f2d5d558056668159f9153bf21d2c53d16.zip
op-kernel-dev-5fcc57f2d5d558056668159f9153bf21d2c53d16.tar.gz
freezer: fix PF_NOFREEZE vs freezeable race
This patch fixes the race pointed out by Oleg Nesterov. * Freezer marks a thread as freezeable. * The thread now marks itself PF_NOFREEZE, but it will be frozen on on calling try_to_freeze(). Thus the task is frozen, even though it doesn't want to. * Subsequent thaw_processes() will also fail to thaw the task since it is marked PF_NOFREEZE. Avoid this problem by checking the task's PF_NOFREEZE status in frozen_processes() before marking the task as frozen. Signed-off-by: Gautham R Shenoy <ego@in.ibm.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Pavel Machek <pavel@ucw.cz> 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>
Diffstat (limited to 'include')
-rw-r--r--include/linux/freezer.h6
1 files changed, 4 insertions, 2 deletions
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index c943525..1045ee9 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -63,8 +63,10 @@ static inline int thaw_process(struct task_struct *p)
*/
static inline void frozen_process(struct task_struct *p)
{
- p->flags |= PF_FROZEN;
- wmb();
+ if (!unlikely(p->flags & PF_NOFREEZE)) {
+ p->flags |= PF_FROZEN;
+ wmb();
+ }
clear_tsk_thread_flag(p, TIF_FREEZE);
}
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