Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755580Ab3H2OEn (ORCPT ); Thu, 29 Aug 2013 10:04:43 -0400 Received: from szxga01-in.huawei.com ([119.145.14.64]:10159 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755511Ab3H2OEk (ORCPT ); Thu, 29 Aug 2013 10:04:40 -0400 From: Libin To: , , , , , , , , , , , CC: , , , , , , Subject: [PATCH 06/14] irq: Fix invalid wakeup in irq_wait_for_interrupt Date: Thu, 29 Aug 2013 21:57:41 +0800 Message-ID: <1377784669-28140-7-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: 2305 Lines: 76 If this thread is preempted at(or before) location a, and the other thread set the condition(kthread_stop). 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. ----------------------- irq_wait_for_interrupt() ----------------------- ... //location a set_current_state(TASK_INTERRUPTIBLE); //location b while (!kthread_should_stop()) { if (test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags)) { __set_current_state(TASK_RUNNING); return 0; } schedule();//location c set_current_state(TASK_INTERRUPTIBLE); //location d } __set_current_state(TASK_RUNNING); ... The following circumstance will also trigger this issue: At location c, consumer is scheduled out, and be preempted after calling set_current_state(TASK_INTERRUPTIBLE) when it be re-schdeuled. 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/irq/manage.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 514bcfd..09cb02f 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -655,6 +655,7 @@ static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id) static int irq_wait_for_interrupt(struct irqaction *action) { + preempt_disable(); set_current_state(TASK_INTERRUPTIBLE); while (!kthread_should_stop()) { @@ -662,12 +663,16 @@ static int irq_wait_for_interrupt(struct irqaction *action) if (test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags)) { __set_current_state(TASK_RUNNING); + preempt_enable(); return 0; } + preempt_enable(); schedule(); + preempt_disable(); set_current_state(TASK_INTERRUPTIBLE); } __set_current_state(TASK_RUNNING); + preempt_enable(); return -1; } -- 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/