From 2953ef246b058989657e1e77b36b67566ac06f7b Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 2 Oct 2013 11:22:19 +0200 Subject: sched/wait: Change timeout logic Commit 4c663cf ("wait: fix false timeouts when using wait_event_timeout()") introduced an additional condition check after a timeout but there's a few issues; - it forgot one site - it put the check after the main loop; not at the actual timeout check. Cure both; by wrapping the condition (as suggested by Oleg), this avoids double evaluation of 'condition' which could be quite big. Reviewed-by: Oleg Nesterov Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20131002092528.028892896@infradead.org Signed-off-by: Ingo Molnar --- include/linux/wait.h | 24 +++++++++++------------- 1 file changed, 11 insertions(+), 13 deletions(-) (limited to 'include/linux/wait.h') diff --git a/include/linux/wait.h b/include/linux/wait.h index ccf0c529fd37..b2afd665e4ea 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -179,6 +179,14 @@ wait_queue_head_t *bit_waitqueue(void *, int); #define wake_up_interruptible_sync_poll(x, m) \ __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m)) +#define ___wait_cond_timeout(condition, ret) \ +({ \ + bool __cond = (condition); \ + if (__cond && !ret) \ + ret = 1; \ + __cond || !ret; \ +}) + #define __wait_event(wq, condition) \ do { \ DEFINE_WAIT(__wait); \ @@ -217,14 +225,10 @@ do { \ \ for (;;) { \ prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE); \ - if (condition) \ + if (___wait_cond_timeout(condition, ret)) \ break; \ ret = schedule_timeout(ret); \ - if (!ret) \ - break; \ } \ - if (!ret && (condition)) \ - ret = 1; \ finish_wait(&wq, &__wait); \ } while (0) @@ -299,18 +303,14 @@ do { \ \ for (;;) { \ prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \ - if (condition) \ + if (___wait_cond_timeout(condition, ret)) \ break; \ if (signal_pending(current)) { \ ret = -ERESTARTSYS; \ break; \ } \ ret = schedule_timeout(ret); \ - if (!ret) \ - break; \ } \ - if (!ret && (condition)) \ - ret = 1; \ finish_wait(&wq, &__wait); \ } while (0) @@ -815,7 +815,7 @@ do { \ \ for (;;) { \ prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \ - if (condition) \ + if (___wait_cond_timeout(condition, ret)) \ break; \ if (signal_pending(current)) { \ ret = -ERESTARTSYS; \ @@ -824,8 +824,6 @@ do { \ spin_unlock_irq(&lock); \ ret = schedule_timeout(ret); \ spin_lock_irq(&lock); \ - if (!ret) \ - break; \ } \ finish_wait(&wq, &__wait); \ } while (0) -- cgit v1.2.1