Commit-ID: a63b03e2d2477586440741677ecac45bcf28d7b1 Gitweb: http://git.kernel.org/tip/a63b03e2d2477586440741677ecac45bcf28d7b1 Author: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> AuthorDate: Tue, 6 Jan 2015 10:29:35 +0000 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Fri, 9 Jan 2015 11:20:39 +0100 mutex: Always clear owner field upon mutex_unlock() 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 <chris@xxxxxxxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Acked-by: Davidlohr Bueso <dave@xxxxxxxxxxxx> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/1420540175-30204-1-git-send-email-chris@xxxxxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- 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 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); } -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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