From: Chuansheng Liu <chuansheng.liu@intel.com>
Date: Wed, 4 Dec 2013 05:58:13 +0000 (+0800)
Subject: mutexes: Give more informative mutex warning in the !lock->owner case
X-Git-Tag: v3.14-rc1~175^2~11
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=91f30a17024ff0d8345e11228af33ee938b13426;p=pandora-kernel.git

mutexes: Give more informative mutex warning in the !lock->owner case

When mutex debugging is enabled and an imbalanced mutex_unlock()
is called, we get the following, slightly confusing warning:

  [  364.208284] DEBUG_LOCKS_WARN_ON(lock->owner != current)

But in that case the warning is due to an imbalanced mutex_unlock() call,
and the lock->owner is NULL - so the message is misleading.

So improve the message by testing for this case specifically:

   DEBUG_LOCKS_WARN_ON(!lock->owner)

Signed-off-by: Liu, Chuansheng <chuansheng.liu@intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1386136693.3650.48.camel@cliu38-desktop-build
[ Improved the changelog, changed the patch to use !lock->owner consistently. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

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