linux-kernel - [tip:core/urgent] locking/mutex: Fix debug

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Message-ID: <tip-a227960fe0cafcc229a8d6bb8b454a3a0b33719d@git.kernel.org>
Date:	Mon, 14 Apr 2014 00:22:17 -0700
From:	tip-bot for Peter Zijlstra <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Valdis.Kletnieks@...edu,
	mlsemon35@...il.com, hpa@...or.com, mingo@...nel.org,
	peterz@...radead.org, jason.low2@...com, davej@...hat.com,
	tglx@...utronix.de, kirill@...temov.name
Subject: [tip:core/urgent] locking/mutex: Fix debug_mutexes

Commit-ID:  a227960fe0cafcc229a8d6bb8b454a3a0b33719d
Gitweb:     http://git.kernel.org/tip/a227960fe0cafcc229a8d6bb8b454a3a0b33719d
Author:     Peter Zijlstra <peterz@...radead.org>
AuthorDate: Thu, 10 Apr 2014 16:15:59 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 11 Apr 2014 10:40:35 +0200

locking/mutex: Fix debug_mutexes

debug_mutex_unlock() would bail when !debug_locks and forgets to
actually unlock.

Reported-by: "Michael L. Semon" <mlsemon35@...il.com>
Reported-by: "Kirill A. Shutemov" <kirill@...temov.name>
Reported-by: Valdis Kletnieks <Valdis.Kletnieks@...edu>
Fixes: 6f008e72cd11 ("locking/mutex: Fix debug checks")
Tested-by: Dave Jones <davej@...hat.com>
Cc: Jason Low <jason.low2@...com>
Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Link: http://lkml.kernel.org/r/20140410141559.GE13658@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/locking/mutex-debug.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c
index e1191c9..5cf6731 100644
--- a/kernel/locking/mutex-debug.c
+++ b/kernel/locking/mutex-debug.c
@@ -71,18 +71,17 @@ void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
 
 void debug_mutex_unlock(struct mutex *lock)
 {
-	if (unlikely(!debug_locks))
-		return;
+	if (likely(debug_locks)) {
+		DEBUG_LOCKS_WARN_ON(lock->magic != lock);
 
-	DEBUG_LOCKS_WARN_ON(lock->magic != lock);
+		if (!lock->owner)
+			DEBUG_LOCKS_WARN_ON(!lock->owner);
+		else
+			DEBUG_LOCKS_WARN_ON(lock->owner != current);
 
-	if (!lock->owner)
-		DEBUG_LOCKS_WARN_ON(!lock->owner);
-	else
-		DEBUG_LOCKS_WARN_ON(lock->owner != current);
-
-	DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
-	mutex_clear_owner(lock);
+		DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
+		mutex_clear_owner(lock);
+	}
 
 	/*
 	 * __mutex_slowpath_needs_to_unlock() is explicitly 0 for debug
--
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