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authorOleg Nesterov <oleg@redhat.com>2011-11-23 09:28:17 -0800
committerTejun Heo <tj@kernel.org>2011-11-23 09:28:17 -0800
commit24b7ead3fb0bae267c2ee50898eb4c13aedd1e9f (patch)
tree899a48d29daebb6e2eb9398797304985e5961fc8 /include/linux/freezer.h
parent34b087e48367c252e343c2f8de65676a78af1e4a (diff)
freezer: fix wait_event_freezable/__thaw_task races
wait_event_freezable() and friends stop the waiting if try_to_freeze() fails. This is not right, we can race with __thaw_task() and in this case - wait_event_freezable() returns the wrong ERESTARTSYS - wait_event_freezable_timeout() can return the positive value while condition == F Change the code to always check __retval/condition before return. Note: with or without this patch the timeout logic looks strange, probably we should recalc timeout if try_to_freeze() returns T. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'include/linux/freezer.h')
-rw-r--r--include/linux/freezer.h18
1 files changed, 10 insertions, 8 deletions
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index a33550fc05c5..09570ac22be6 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -122,28 +122,30 @@ static inline int freezer_should_skip(struct task_struct *p)
#define wait_event_freezable(wq, condition) \
({ \
int __retval; \
- do { \
+ for (;;) { \
__retval = wait_event_interruptible(wq, \
(condition) || freezing(current)); \
- if (__retval && !freezing(current)) \
+ if (__retval || (condition)) \
break; \
- else if (!(condition)) \
- __retval = -ERESTARTSYS; \
- } while (try_to_freeze()); \
+ try_to_freeze(); \
+ } \
__retval; \
})
-
#define wait_event_freezable_timeout(wq, condition, timeout) \
({ \
long __retval = timeout; \
- do { \
+ for (;;) { \
__retval = wait_event_interruptible_timeout(wq, \
(condition) || freezing(current), \
__retval); \
- } while (try_to_freeze()); \
+ if (__retval <= 0 || (condition)) \
+ break; \
+ try_to_freeze(); \
+ } \
__retval; \
})
+
#else /* !CONFIG_FREEZER */
static inline bool frozen(struct task_struct *p) { return false; }
static inline bool freezing(struct task_struct *p) { return false; }