From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753844Ab3JBJxE (ORCPT ); Wed, 2 Oct 2013 05:53:04 -0400 Received: from merlin.infradead.org ([205.233.59.134]:41085 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753464Ab3JBJvn (ORCPT ); Wed, 2 Oct 2013 05:51:43 -0400 Message-Id: <20131002092528.028892896@infradead.org> User-Agent: quilt/0.60-1 Date: Wed, 02 Oct 2013 11:22:19 +0200 From: Peter Zijlstra To: Ingo Molnar Cc: Oleg Nesterov , Paul McKenney , Linus Torvalds , Thomas Gleixner , Andrew Morton , linux-kernel@vger.kernel.org, Peter Zijlstra Subject: [PATCH 02/16] sched/wait: Change timeout logic References: <20131002092217.784439754@infradead.org> Content-Disposition: inline; filename=peterz-wait-change-sched-timo.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- include/linux/wait.h | 24 +++++++++++------------- 1 file changed, 11 insertions(+), 13 deletions(-) --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -179,6 +179,14 @@ wait_queue_head_t *bit_waitqueue(void *, #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)