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 <ch...@chris-wilson.co.uk> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Ingo Molnar <mi...@redhat.com> Cc: Daniel Vetter <daniel.vet...@ffwll.ch> --- kernel/locking/mutex-debug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c index 5cf6731b98e9..3ef3736002d8 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); } -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
