Revert "rtmutex: Handle the various new futex race conditions"

[ Upstream commit 9e0265c21af4d6388d47dcd5ce20f76ec3a2e468 ]

Drop the RT fixup, the futex code will be changed to avoid the need for
the workaround.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 6 insertions, 30 deletions

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 7f6f402e04ae..44a33057a83a 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -142,11 +142,6 @@ static void fixup_rt_mutex_waiters(struct rt_mutex *lock)
 		WRITE_ONCE(*p, owner & ~RT_MUTEX_HAS_WAITERS);
 }
 
-static int rt_mutex_real_waiter(struct rt_mutex_waiter *waiter)
-{
-	return waiter && waiter != PI_WAKEUP_INPROGRESS;
-}
-
 /*
  * We can speed up the acquire/release, if there's no debugging state to be
  * set up.
@@ -420,8 +415,7 @@ int max_lock_depth = 1024;
 
 static inline struct rt_mutex *task_blocked_on_lock(struct task_struct *p)
 {
-	return rt_mutex_real_waiter(p->pi_blocked_on) ?
-		p->pi_blocked_on->lock : NULL;
+	return p->pi_blocked_on ? p->pi_blocked_on->lock : NULL;
 }
 
 /*
@@ -557,7 +551,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
 	 * reached or the state of the chain has changed while we
 	 * dropped the locks.
 	 */
-	if (!rt_mutex_real_waiter(waiter))
+	if (!waiter)
 		goto out_unlock_pi;
 
 	/*
@@ -1327,22 +1321,6 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
 		return -EDEADLK;
 
 	raw_spin_lock(&task->pi_lock);
-	/*
-	 * In the case of futex requeue PI, this will be a proxy
-	 * lock. The task will wake unaware that it is enqueueed on
-	 * this lock. Avoid blocking on two locks and corrupting
-	 * pi_blocked_on via the PI_WAKEUP_INPROGRESS
-	 * flag. futex_wait_requeue_pi() sets this when it wakes up
-	 * before requeue (due to a signal or timeout). Do not enqueue
-	 * the task if PI_WAKEUP_INPROGRESS is set.
-	 */
-	if (task != current && task->pi_blocked_on == PI_WAKEUP_INPROGRESS) {
-		raw_spin_unlock(&task->pi_lock);
-		return -EAGAIN;
-	}
-
-       BUG_ON(rt_mutex_real_waiter(task->pi_blocked_on));
-
 	waiter->task = task;
 	waiter->lock = lock;
 	waiter->prio = task->prio;
@@ -1366,7 +1344,7 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
 		rt_mutex_enqueue_pi(owner, waiter);
 
 		rt_mutex_adjust_prio(owner);
-		if (rt_mutex_real_waiter(owner->pi_blocked_on))
+		if (owner->pi_blocked_on)
 			chain_walk = 1;
 	} else if (rt_mutex_cond_detect_deadlock(waiter, chwalk)) {
 		chain_walk = 1;
@@ -1466,7 +1444,7 @@ static void remove_waiter(struct rt_mutex *lock,
 {
 	bool is_top_waiter = (waiter == rt_mutex_top_waiter(lock));
 	struct task_struct *owner = rt_mutex_owner(lock);
-	struct rt_mutex *next_lock = NULL;
+	struct rt_mutex *next_lock;
 
 	lockdep_assert_held(&lock->wait_lock);
 
@@ -1492,8 +1470,7 @@ static void remove_waiter(struct rt_mutex *lock,
 	rt_mutex_adjust_prio(owner);
 
 	/* Store the lock on which owner is blocked or NULL */
-	if (rt_mutex_real_waiter(owner->pi_blocked_on))
-		next_lock = task_blocked_on_lock(owner);
+	next_lock = task_blocked_on_lock(owner);
 
 	raw_spin_unlock(&owner->pi_lock);
 
@@ -1529,8 +1506,7 @@ void rt_mutex_adjust_pi(struct task_struct *task)
 	raw_spin_lock_irqsave(&task->pi_lock, flags);
 
 	waiter = task->pi_blocked_on;
-	if (!rt_mutex_real_waiter(waiter) ||
-	    rt_mutex_waiter_equal(waiter, task_to_waiter(task))) {
+	if (!waiter || rt_mutex_waiter_equal(waiter, task_to_waiter(task))) {
 		raw_spin_unlock_irqrestore(&task->pi_lock, flags);
 		return;
 	}