wait_event_freezable() and wait_event_freezable_timeout() 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@xxxxxxxxxx>
---
include/linux/freezer.h | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)
--- 3.1/include/linux/freezer.h~w_e_f 2011-09-04 20:23:30.000000000 +0200
+++ 3.1/include/linux/freezer.h 2011-09-07 20:00:27.000000000 +0200
@@ -107,32 +107,33 @@ static inline int freezer_should_skip(st
* Freezer-friendly wrappers around wait_event_interruptible() and
* wait_event_interruptible_timeout(), originally defined in <linux/wait.h>
*/
-
#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; }
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