user/sven/linux.git/kernel/locking/mutex-debug.c, branch v4.4.2

mutex: Always clear owner field upon mutex_unlock()

2015-01-09T10:20:39Z

Currently if DEBUG_MUTEXES is enabled, the mutex->owner field is only cleared iff debug_locks is active. This exposes a race to other users of the field where the mutex->owner may be still set to a stale value, potentially upsetting mutex_spin_on_owner() among others. References: https://bugs.freedesktop.org/show_bug.cgi?id=87955 Signed-off-by: Chris Wilson Signed-off-by: Peter Zijlstra (Intel) Acked-by: Davidlohr Bueso Cc: Daniel Vetter Cc: Linus Torvalds Link: http://lkml.kernel.org/r/1420540175-30204-1-git-send-email-chris@chris-wilson.co.uk Signed-off-by: Ingo Molnar

locking/mutex: Fix debug_mutexes

2014-04-11T08:40:35Z

debug_mutex_unlock() would bail when !debug_locks and forgets to actually unlock. Reported-by: "Michael L. Semon" Reported-by: "Kirill A. Shutemov" Reported-by: Valdis Kletnieks Fixes: 6f008e72cd11 ("locking/mutex: Fix debug checks") Tested-by: Dave Jones Cc: Jason Low Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20140410141559.GE13658@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar

locking/mutex: Fix debug checks

2014-03-12T12:49:47Z

OK, so commit: 1d8fe7dc8078 ("locking/mutexes: Unlock the mutex without the wait_lock") generates this boot warning when CONFIG_DEBUG_MUTEXES=y: WARNING: CPU: 0 PID: 139 at /usr/src/linux-2.6/kernel/locking/mutex-debug.c:82 debug_mutex_unlock+0x155/0x180() DEBUG_LOCKS_WARN_ON(lock->owner != current) And that makes sense, because as soon as we release the lock a new owner can come in... One would think that !__mutex_slowpath_needs_to_unlock() implementations suffer the same, but for DEBUG we fall back to mutex-null.h which has an unconditional 1 for that. The mutex debug code requires the mutex to be unlocked after doing the debug checks, otherwise it can find inconsistent state. Reported-by: Ingo Molnar Signed-off-by: Peter Zijlstra Cc: jason.low2@hp.com Link: http://lkml.kernel.org/r/20140312122442.GB27965@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar

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

2013-12-17T14:35:10Z

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 Signed-off-by: Peter Zijlstra Cc: Linus Torvalds Cc: Andrew Morton Cc: Thomas Gleixner Cc: Paul E. McKenney 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

locking: Move the mutex code to kernel/locking/

2013-11-06T06:55:07Z

Suggested-by: Ingo Molnar Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/n/tip-1ditvncg30dgbpvrz2bxfmke@git.kernel.org Signed-off-by: Ingo Molnar