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| author | Oleg Nesterov <oleg@redhat.com> | 2011-11-23 09:28:17 -0800 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2011-11-23 09:28:17 -0800 |
| commit | 24b7ead3fb0bae267c2ee50898eb4c13aedd1e9f (patch) | |
| tree | 899a48d29daebb6e2eb9398797304985e5961fc8 | |
| parent | 34b087e48367c252e343c2f8de65676a78af1e4a (diff) | |
| download | olio-linux-3.10-24b7ead3fb0bae267c2ee50898eb4c13aedd1e9f.tar.xz olio-linux-3.10-24b7ead3fb0bae267c2ee50898eb4c13aedd1e9f.zip | |
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>
| -rw-r--r-- | include/linux/freezer.h | 18 |
1 files changed, 10 insertions, 8 deletions
diff --git a/include/linux/freezer.h b/include/linux/freezer.h index a33550fc05c..09570ac22be 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; } |