futex: Drop refcount if requeue_pi() acquired the rtmutex

If the proxy lock in the requeue loop acquires the rtmutex for a waiter then it acquired also refcount on the pi_state related to the futex, but the waiter side does not drop the reference count. Add the missing free_pi_state() call. Signed-off-by: Thomas Gleixner <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Darren Hart <[email protected]> Cc: Davidlohr Bueso <[email protected]> Cc: [email protected] Cc: Andy Lowe <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Thomas Gleixner <[email protected]> Cc: [email protected]
beagleboard · Dec 20, 2015 · fb75a42 · fb75a42
1 parent 2d142e5
commit fb75a42
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/kernel/futex.c b/kernel/futex.c
@@ -2755,6 +2755,11 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 		if (q.pi_state && (q.pi_state->owner != current)) {
 			spin_lock(q.lock_ptr);
 			ret = fixup_pi_state_owner(uaddr2, &q, current);
+			/*
+			 * Drop the reference to the pi state which
+			 * the requeue_pi() code acquired for us.
+			 */
+			free_pi_state(q.pi_state);
 			spin_unlock(q.lock_ptr);
 		}
 	} else {