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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Lai Jiangshan <laijs@cn.fujitsu.com>,
	Jason Low <jason.low2@hp.com>, Brad Mouring <bmouring@ni.com>
Subject: [patch V3 1/7] rtmutex: Deobfuscate chain walk
Date: Mon, 09 Jun 2014 20:28:06 -0000	[thread overview]
Message-ID: <20140609202335.980283946@linutronix.de> (raw)
In-Reply-To: <20140609201118.387571774@linutronix.de>

[-- Attachment #1: rtmutex-deobfuscate-chain-walk.patch --]
[-- Type: text/plain, Size: 1092 bytes --]

There is no point to keep the task ref across the check for lock
owner. Drop the ref before that, so the protection context is clear.

Found while documenting the chain walk.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/locking/rtmutex.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Index: tip/kernel/locking/rtmutex.c
===================================================================
--- tip.orig/kernel/locking/rtmutex.c
+++ tip/kernel/locking/rtmutex.c
@@ -411,6 +411,8 @@ static int rt_mutex_adjust_prio_chain(st
 
 	/* Release the task */
 	raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+	put_task_struct(task);
+
 	if (!rt_mutex_owner(lock)) {
 		/*
 		 * If the requeue above changed the top waiter, then we need
@@ -420,9 +422,8 @@ static int rt_mutex_adjust_prio_chain(st
 		if (top_waiter != rt_mutex_top_waiter(lock))
 			wake_up_process(rt_mutex_top_waiter(lock)->task);
 		raw_spin_unlock(&lock->wait_lock);
-		goto out_put_task;
+		return 0;
 	}
-	put_task_struct(task);
 
 	/* Grab the next task */
 	task = rt_mutex_owner(lock);



  reply	other threads:[~2014-06-09 20:28 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-06-09 20:28 [patch V3 0/7] rtmutex: Code clarification and optimization Thomas Gleixner
2014-06-09 20:28 ` Thomas Gleixner [this message]
2014-06-09 20:59   ` [patch V3 1/7] rtmutex: Deobfuscate chain walk Steven Rostedt
2014-06-10  3:52     ` Lai Jiangshan
2014-06-10  3:21   ` Jason Low
2014-06-10 13:57   ` Brad Mouring
2014-06-09 20:28 ` [patch V3 2/7] rtmutex: Clarify the boost/deboost part Thomas Gleixner
2014-06-10  0:37   ` Steven Rostedt
2014-06-10  3:22   ` Jason Low
2014-06-10 14:04   ` Brad Mouring
2014-06-09 20:28 ` [patch V3 3/7] rtmutex: Document pi chain walk Thomas Gleixner
2014-06-10  0:45   ` Steven Rostedt
2014-06-10  3:51     ` Lai Jiangshan
2014-06-10 14:21   ` Brad Mouring
2014-06-09 20:28 ` [patch V3 4/7] rtmutex: Siplify remove_waiter() Thomas Gleixner
2014-06-10  0:53   ` Steven Rostedt
2014-06-10  3:35     ` Lai Jiangshan
2014-06-10  3:44     ` Jason Low
2014-06-10 14:10   ` Brad Mouring
2014-06-09 20:28 ` [patch V3 5/7] rtmutex: Confine deadlock logic to futex Thomas Gleixner
2014-06-10  0:59   ` Steven Rostedt
2014-06-10  4:03     ` Lai Jiangshan
2014-06-10 17:39     ` Thomas Gleixner
2014-06-09 20:28 ` [patch V3 6/7] rtmutex: Cleanup deadlock detector debug logic Thomas Gleixner
2014-06-10  1:04   ` Steven Rostedt
2014-06-10 15:09   ` Brad Mouring
2014-06-09 20:28 ` [patch V3 7/7] rtmutex: Avoid pointless requeueing in the deadlock detection chain walk Thomas Gleixner
2014-06-10  1:20   ` Steven Rostedt
2014-06-10  3:48     ` Jason Low
2014-06-10 17:41     ` Thomas Gleixner
2014-06-10 17:47       ` Steven Rostedt
2014-06-10 20:45         ` Thomas Gleixner
2014-06-10 14:57   ` Brad Mouring
2014-06-10 15:19     ` Steven Rostedt
2014-06-10 17:43       ` Thomas Gleixner
2014-06-10 17:51         ` Steven Rostedt
2014-06-10 20:46           ` Thomas Gleixner
2014-06-10  0:27 ` [patch V3 0/7] rtmutex: Code clarification and optimization Steven Rostedt
2014-06-10  0:35   ` Steven Rostedt
2014-06-10  3:00     ` Lai Jiangshan

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