Eric Lee / smarc-ti-linux-kernel

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Commit 91f30a17024ff0d8345e11228af33ee938b13426

Authored by Chuansheng Liu
Committed by Ingo Molnar
1 parent bb799d3b98
Exists in master and in 16 other branches dlt-processor-sdk-linux-03.00.00.04, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

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>

Showing 1 changed file with 6 additions and 1 deletions Side-by-side Diff

kernel/locking/mutex-debug.c
Diff comments   View file @ 91f30a1
... ... @@ -75,7 +75,12 @@
75 75 return;
76 76  
77 77 DEBUG_LOCKS_WARN_ON(lock->magic != lock);
78   - DEBUG_LOCKS_WARN_ON(lock->owner != current);
  78 +
  79 + if (!lock->owner)
  80 + DEBUG_LOCKS_WARN_ON(!lock->owner);
  81 + else
  82 + DEBUG_LOCKS_WARN_ON(lock->owner != current);
  83 +
79 84 DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
80 85 mutex_clear_owner(lock);
81 86 }