commit 1b190aef79b0e83bd8fccdc267a1761968f4a20a
Author: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Date:   Tue Apr 16 03:30:56 2019 +0200

    Revert "futex,rt_mutex: Restructure rt_mutex_finish_proxy_lock()"
    
    This reverts commit ce813552312bfbb28bae32064d65afff3c0e7c82.

diff --git a/kernel/futex.c b/kernel/futex.c
index 30fe0432c46d..053d7be08be5 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2966,13 +2966,10 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 		 */
 		WARN_ON(!q.pi_state);
 		pi_mutex = &q.pi_state->pi_mutex;
-		ret = rt_mutex_wait_proxy_lock(pi_mutex, to, &rt_waiter);
+		ret = rt_mutex_finish_proxy_lock(pi_mutex, to, &rt_waiter);
+		debug_rt_mutex_free_waiter(&rt_waiter);
 
 		spin_lock(q.lock_ptr);
-		if (ret && !rt_mutex_cleanup_proxy_lock(pi_mutex, &rt_waiter))
-			ret = 0;
-
-		debug_rt_mutex_free_waiter(&rt_waiter);
 		/*
 		 * Fixup the pi_state owner and possibly acquire the lock if we
 		 * haven't already.
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 7615e7722258..196cc460e38d 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1746,23 +1746,21 @@ struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock)
 }
 
 /**
- * rt_mutex_wait_proxy_lock() - Wait for lock acquisition
+ * rt_mutex_finish_proxy_lock() - Complete lock acquisition
  * @lock:		the rt_mutex we were woken on
  * @to:			the timeout, null if none. hrtimer should already have
  *			been started.
  * @waiter:		the pre-initialized rt_mutex_waiter
  *
- * Wait for the the lock acquisition started on our behalf by
- * rt_mutex_start_proxy_lock(). Upon failure, the caller must call
- * rt_mutex_cleanup_proxy_lock().
+ * Complete the lock acquisition started our behalf by another thread.
  *
  * Returns:
  *  0 - success
  * <0 - error, one of -EINTR, -ETIMEDOUT
  *
- * Special API call for PI-futex support
+ * Special API call for PI-futex requeue support
  */
-int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
+int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
 			       struct hrtimer_sleeper *to,
 			       struct rt_mutex_waiter *waiter)
 {
@@ -1775,6 +1773,9 @@ int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
 	/* sleep on the mutex */
 	ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter);
 
+	if (unlikely(ret))
+		remove_waiter(lock, waiter);
+
 	/*
 	 * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
 	 * have to fix that up.
@@ -1785,42 +1786,3 @@ int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
 
 	return ret;
 }
-
-/**
- * rt_mutex_cleanup_proxy_lock() - Cleanup failed lock acquisition
- * @lock:		the rt_mutex we were woken on
- * @waiter:		the pre-initialized rt_mutex_waiter
- *
- * Attempt to clean up after a failed rt_mutex_wait_proxy_lock().
- *
- * Unless we acquired the lock; we're still enqueued on the wait-list and can
- * in fact still be granted ownership until we're removed. Therefore we can
- * find we are in fact the owner and must disregard the
- * rt_mutex_wait_proxy_lock() failure.
- *
- * Returns:
- *  true  - did the cleanup, we done.
- *  false - we acquired the lock after rt_mutex_wait_proxy_lock() returned,
- *          caller should disregards its return value.
- *
- * Special API call for PI-futex support
- */
-bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
-				 struct rt_mutex_waiter *waiter)
-{
-	bool cleanup = false;
-
-	raw_spin_lock_irq(&lock->wait_lock);
-	/*
-	 * Unless we're the owner; we're still enqueued on the wait_list.
-	 * So check if we became owner, if not, take us off the wait_list.
-	 */
-	if (rt_mutex_owner(lock) != current) {
-		remove_waiter(lock, waiter);
-		fixup_rt_mutex_waiters(lock);
-		cleanup = true;
-	}
-	raw_spin_unlock_irq(&lock->wait_lock);
-
-	return cleanup;
-}
diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
index 14cbafed0014..50848b460851 100644
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -107,11 +107,9 @@ extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
 extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
 				     struct rt_mutex_waiter *waiter,
 				     struct task_struct *task);
-extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
-			       struct hrtimer_sleeper *to,
-			       struct rt_mutex_waiter *waiter);
-extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
-				 struct rt_mutex_waiter *waiter);
+extern int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
+				      struct hrtimer_sleeper *to,
+				      struct rt_mutex_waiter *waiter);
 extern int rt_mutex_timed_futex_lock(struct rt_mutex *l, struct hrtimer_sleeper *to);
 extern bool rt_mutex_futex_unlock(struct rt_mutex *lock,
 				  struct wake_q_head *wqh);