Chris Wilson 226e5ae9e5 drm/i915: Fix mutex->owner inspection race under DEBUG_MUTEXES ... If CONFIG_DEBUG_MUTEXES is set, the mutex->owner field is only cleared if the mutex debugging is enabled which introduces a race in our mutex_is_locked_by() - i.e. we may inspect the old owner value before it is acquired by the new task. This is the root cause of this error: diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c index 5cf6731..3ef3736 100644 --- a/kernel/locking/mutex-debug.c +++ b/kernel/locking/mutex-debug.c @@ -80,13 +80,13 @@ void debug_mutex_unlock(struct mutex *lock) DEBUG_LOCKS_WARN_ON(lock->owner != current); 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 * mutexes so that we can do it here after we've verified state. */ + mutex_clear_owner(lock); atomic_set(&lock->count, 1); } Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=87955 Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: stable@vger.kernel.org Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Jani Nikula <jani.nikula@intel.com>		2015-01-12 10:53:02 +02:00
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drm	drm/i915: Fix mutex->owner inspection race under DEBUG_MUTEXES	2015-01-12 10:53:02 +02:00
host1x	gpu: host1x: mipi: Set MIPI_CAL_BIAS_PAD_CFG1 register	2014-11-13 16:11:57 +01:00
ipu-v3	[media] gpu: ipu-v3: Make use of media_bus_format enum	2014-11-14 17:55:27 -02:00
vga	Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2014-10-13 16:23:15 +02:00
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