Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755447Ab3H2ODR (ORCPT ); Thu, 29 Aug 2013 10:03:17 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:20538 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754253Ab3H2OBv (ORCPT ); Thu, 29 Aug 2013 10:01:51 -0400 From: Libin To: , , , , , , , , , , , CC: , , , , , , Subject: [PATCH 09/14] rcutree: Fix invalid wakeup in rcu_wait Date: Thu, 29 Aug 2013 21:57:44 +0800 Message-ID: <1377784669-28140-10-git-send-email-huawei.libin@huawei.com> X-Mailer: git-send-email 1.8.1.msysgit.1 In-Reply-To: <1377784669-28140-1-git-send-email-huawei.libin@huawei.com> References: <1377784669-28140-1-git-send-email-huawei.libin@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.135.74.57] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1429 Lines: 45 If thread is preempted before calling set_current_state(TASK_INTERRUPTIBLE), and the other thread set the condition followed with wake_up_process. After that when this thread is re-scheduled, calling set_current_state to set itself as state TASK_INTERRUPTIBLE, if it is preempted again after that and before __set_current_state(TASK_RUNNING), it triggers the invalid wakeup problem. To solve this problem, using preempt_disable() to bound the operaion that setting the task state and the conditions(set by the wake thread) validation. Signed-off-by: Libin --- kernel/rcutree.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/rcutree.h b/kernel/rcutree.h index b383258..e3f1278 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -357,13 +357,17 @@ struct rcu_data { #define rcu_wait(cond) \ do { \ + preempt_disable(); \ for (;;) { \ set_current_state(TASK_INTERRUPTIBLE); \ if (cond) \ break; \ + preempt_enable(); \ schedule(); \ + preempt_disable(); \ } \ __set_current_state(TASK_RUNNING); \ + preempt_enable(); \ } while (0) /* -- 1.8.2.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/