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Message-ID: <1377784669-28140-10-git-send-email-huawei.libin@huawei.com>
Date: Thu, 29 Aug 2013 21:57:44 +0800
From: Libin <huawei.libin@...wei.com>
To: <akpm@...ux-foundation.org>, <tj@...nel.org>,
<viro@...iv.linux.org.uk>, <eparis@...hat.com>,
<tglx@...utronix.de>, <rusty@...tcorp.com.au>,
<ebiederm@...ssion.com>, <paulmck@...ux.vnet.ibm.com>,
<john.stultz@...aro.org>, <mingo@...hat.com>,
<peterz@...radead.org>, <gregkh@...uxfoundation.org>
CC: <linux-kernel@...r.kernel.org>, <lizefan@...wei.com>,
<jovi.zhangwei@...wei.com>, <guohanjun@...wei.com>,
<zhangdianfang@...wei.com>, <wangyijing@...wei.com>,
<huawei.libin@...wei.com>
Subject: [PATCH 09/14] rcutree: Fix invalid wakeup in rcu_wait
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 <huawei.libin@...wei.com>
---
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
--
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