1 files changed, 15 insertions, 62 deletions

diff --git a/kernel/futex.c b/kernel/futex.c
index a58af833bb77..1d9423914bf4 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2147,16 +2147,6 @@ retry_private:
 				requeue_pi_wake_futex(this, &key2, hb2);
 				drop_count++;
 				continue;
-			} else if (ret == -EAGAIN) {
-				/*
-				 * Waiter was woken by timeout or
-				 * signal and has set pi_blocked_on to
-				 * PI_WAKEUP_INPROGRESS before we
-				 * tried to enqueue it on the rtmutex.
-				 */
-				this->pi_state = NULL;
-				put_pi_state(pi_state);
-				continue;
 			} else if (ret) {
 				/*
 				 * rt_mutex_start_proxy_lock() detected a
@@ -3235,7 +3225,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 	struct hrtimer_sleeper timeout, *to = NULL;
 	struct futex_pi_state *pi_state = NULL;
 	struct rt_mutex_waiter rt_waiter;
-	struct futex_hash_bucket *hb, *hb2;
+	struct futex_hash_bucket *hb;
 	union futex_key key2 = FUTEX_KEY_INIT;
 	struct futex_q q = futex_q_init;
 	int res, ret;
@@ -3293,55 +3283,20 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 	/* Queue the futex_q, drop the hb lock, wait for wakeup. */
 	futex_wait_queue_me(hb, &q, to);
 
-	/*
-	 * On RT we must avoid races with requeue and trying to block
-	 * on two mutexes (hb->lock and uaddr2's rtmutex) by
-	 * serializing access to pi_blocked_on with pi_lock.
-	 */
-	raw_spin_lock_irq(&current->pi_lock);
-	if (current->pi_blocked_on) {
-		/*
-		 * We have been requeued or are in the process of
-		 * being requeued.
-		 */
-		raw_spin_unlock_irq(&current->pi_lock);
-	} else {
-		/*
-		 * Setting pi_blocked_on to PI_WAKEUP_INPROGRESS
-		 * prevents a concurrent requeue from moving us to the
-		 * uaddr2 rtmutex. After that we can safely acquire
-		 * (and possibly block on) hb->lock.
-		 */
-		current->pi_blocked_on = PI_WAKEUP_INPROGRESS;
-		raw_spin_unlock_irq(&current->pi_lock);
-
-		spin_lock(&hb->lock);
-
-		/*
-		 * Clean up pi_blocked_on. We might leak it otherwise
-		 * when we succeeded with the hb->lock in the fast
-		 * path.
-		 */
-		raw_spin_lock_irq(&current->pi_lock);
-		current->pi_blocked_on = NULL;
-		raw_spin_unlock_irq(&current->pi_lock);
-
-		ret = handle_early_requeue_pi_wakeup(hb, &q, &key2, to);
-		spin_unlock(&hb->lock);
-		if (ret)
-			goto out_put_keys;
-	}
+	spin_lock(&hb->lock);
+	ret = handle_early_requeue_pi_wakeup(hb, &q, &key2, to);
+	spin_unlock(&hb->lock);
+	if (ret)
+		goto out_put_keys;
 
 	/*
-	 * In order to be here, we have either been requeued, are in
-	 * the process of being requeued, or requeue successfully
-	 * acquired uaddr2 on our behalf.  If pi_blocked_on was
-	 * non-null above, we may be racing with a requeue.  Do not
-	 * rely on q->lock_ptr to be hb2->lock until after blocking on
-	 * hb->lock or hb2->lock. The futex_requeue dropped our key1
-	 * reference and incremented our key2 reference count.
+	 * In order for us to be here, we know our q.key == key2, and since
+	 * we took the hb->lock above, we also know that futex_requeue() has
+	 * completed and we no longer have to concern ourselves with a wakeup
+	 * race with the atomic proxy lock acquisition by the requeue code. The
+	 * futex_requeue dropped our key1 reference and incremented our key2
+	 * reference count.
 	 */
-	hb2 = hash_futex(&key2);
 
 	/* Check if the requeue code acquired the second futex for us. */
 	if (!q.rt_waiter) {
@@ -3350,8 +3305,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 		 * did a lock-steal - fix up the PI-state in that case.
 		 */
 		if (q.pi_state && (q.pi_state->owner != current)) {
-			spin_lock(&hb2->lock);
-			BUG_ON(&hb2->lock != q.lock_ptr);
+			spin_lock(q.lock_ptr);
 			ret = fixup_pi_state_owner(uaddr2, &q, current);
 			if (ret && rt_mutex_owner(&q.pi_state->pi_mutex) == current) {
 				pi_state = q.pi_state;
@@ -3362,7 +3316,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 			 * the requeue_pi() code acquired for us.
 			 */
 			put_pi_state(q.pi_state);
-			spin_unlock(&hb2->lock);
+			spin_unlock(q.lock_ptr);
 		}
 	} else {
 		struct rt_mutex *pi_mutex;
@@ -3376,8 +3330,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 		pi_mutex = &q.pi_state->pi_mutex;
 		ret = rt_mutex_wait_proxy_lock(pi_mutex, to, &rt_waiter);
 
-		spin_lock(&hb2->lock);
-		BUG_ON(&hb2->lock != q.lock_ptr);
+		spin_lock(q.lock_ptr);
 		if (ret && !rt_mutex_cleanup_proxy_lock(pi_mutex, &rt_waiter))
 			ret = 0;