Messages in this thread Patch in this message | | | Date | Fri, 20 Jun 2008 17:21:24 +0200 | From | Ingo Molnar <> | Subject | Re: wait_for_completion_timeout() spurious failure under heavy load? |
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* Oleg Nesterov <oleg@tv-sign.ru> wrote:
> > IOW, how about the patch below? this also makes the code a bit > > simpler because we factor out __remove_wait_queue(). > > Even better, we can kill the first __remove_wait_queue() as well.
nice, thanks - applied it in the form below to tip/sched/urgent.
Ingo
------------------> commit 6b8464474776dccf619283ee5510b0b795382dfb Author: Oleg Nesterov <oleg@tv-sign.ru> Date: Fri Jun 20 18:32:20 2008 +0400
sched: refactor wait_for_completion_timeout() Simplify the code and fix the boundary condition of wait_for_completion_timeout(,0). We can kill the first __remove_wait_queue() as well. Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched.c b/kernel/sched.c index 577f160..bebf978 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4398,32 +4398,20 @@ do_wait_for_common(struct completion *x, long timeout, int state) signal_pending(current)) || (state == TASK_KILLABLE && fatal_signal_pending(current))) { - __remove_wait_queue(&x->wait, &wait); - return -ERESTARTSYS; + timeout = -ERESTARTSYS; + break; } __set_current_state(state); spin_unlock_irq(&x->wait.lock); timeout = schedule_timeout(timeout); spin_lock_irq(&x->wait.lock); - - /* - * If the completion has arrived meanwhile - * then return 1 jiffy time left: - */ - if (x->done && !timeout) { - timeout = 1; - break; - } - - if (!timeout) { - __remove_wait_queue(&x->wait, &wait); - return timeout; - } - } while (!x->done); + } while (!x->done && timeout); __remove_wait_queue(&x->wait, &wait); + if (!x->done) + return timeout; } x->done--; - return timeout; + return timeout ?: 1; } static long __sched
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