Commit bf7a281b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'locking-urgent-2024-12-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull locking fix from Ingo Molnar:
 "Fix missed rtmutex wakeups causing sporadic boot hangs and other
  misbehavior"

* tag 'locking-urgent-2024-12-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/rtmutex: Make sure we wake anything on the wake_q when we release the lock->wait_lock
parents feffd35a 4a077914

kernel/locking/rtmutex.c

+16 −2
Original line number Diff line number Diff line
@@ -1292,7 +1292,13 @@ static int __sched task_blocks_on_rt_mutex(struct rt_mutex_base *lock, 
	 */

	get_task_struct(owner);



	preempt_disable();

	raw_spin_unlock_irq(&lock->wait_lock);

	/* wake up any tasks on the wake_q before calling rt_mutex_adjust_prio_chain */

	wake_up_q(wake_q);

	wake_q_init(wake_q);

	preempt_enable();





	res = rt_mutex_adjust_prio_chain(owner, chwalk, lock,

					 next_lock, waiter, task);
@@ -1596,6 +1602,7 @@ static void __sched remove_waiter(struct rt_mutex_base *lock, 
 *			 or TASK_UNINTERRUPTIBLE)

 * @timeout:		 the pre-initialized and started timer, or NULL for none

 * @waiter:		 the pre-initialized rt_mutex_waiter

 * @wake_q:		 wake_q of tasks to wake when we drop the lock->wait_lock

 *

 * Must be called with lock->wait_lock held and interrupts disabled

 */
@@ -1603,7 +1610,8 @@ static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock, 
					   struct ww_acquire_ctx *ww_ctx,

					   unsigned int state,

					   struct hrtimer_sleeper *timeout,

					   struct rt_mutex_waiter *waiter)

					   struct rt_mutex_waiter *waiter,

					   struct wake_q_head *wake_q)

	__releases(&lock->wait_lock) __acquires(&lock->wait_lock)

{

	struct rt_mutex *rtm = container_of(lock, struct rt_mutex, rtmutex);
@@ -1634,7 +1642,13 @@ static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock, 
			owner = rt_mutex_owner(lock);

		else

			owner = NULL;

		preempt_disable();

		raw_spin_unlock_irq(&lock->wait_lock);

		if (wake_q) {

			wake_up_q(wake_q);

			wake_q_init(wake_q);

		}

		preempt_enable();



		if (!owner || !rtmutex_spin_on_owner(lock, waiter, owner))

			rt_mutex_schedule();
@@ -1708,7 +1722,7 @@ static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock, 


	ret = task_blocks_on_rt_mutex(lock, waiter, current, ww_ctx, chwalk, wake_q);

	if (likely(!ret))

		ret = rt_mutex_slowlock_block(lock, ww_ctx, state, NULL, waiter);

		ret = rt_mutex_slowlock_block(lock, ww_ctx, state, NULL, waiter, wake_q);



	if (likely(!ret)) {

		/* acquired the lock */

kernel/locking/rtmutex_api.c

+1 −1
Original line number Diff line number Diff line
@@ -383,7 +383,7 @@ int __sched rt_mutex_wait_proxy_lock(struct rt_mutex_base *lock, 
	raw_spin_lock_irq(&lock->wait_lock);

	/* sleep on the mutex */

	set_current_state(TASK_INTERRUPTIBLE);

	ret = rt_mutex_slowlock_block(lock, NULL, TASK_INTERRUPTIBLE, to, waiter);

	ret = rt_mutex_slowlock_block(lock, NULL, TASK_INTERRUPTIBLE, to, waiter, NULL);

	/*

	 * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might

	 * have to fix that up.