Fix an rtmutex missed-wakeup bug.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-urgent-2023-02-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking fix from Ingo Molnar:
 "Fix an rtmutex missed-wakeup bug"

* tag 'locking-urgent-2023-02-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rtmutex: Ensure that the top waiter is always woken up
This commit is contained in:
Linus Torvalds 2023-02-11 11:11:18 -08:00
commit 338c847304

View file

@ -901,8 +901,9 @@ static int __sched rt_mutex_adjust_prio_chain(struct task_struct *task,
* then we need to wake the new top waiter up to try
* to get the lock.
*/
if (prerequeue_top_waiter != rt_mutex_top_waiter(lock))
wake_up_state(waiter->task, waiter->wake_state);
top_waiter = rt_mutex_top_waiter(lock);
if (prerequeue_top_waiter != top_waiter)
wake_up_state(top_waiter->task, top_waiter->wake_state);
raw_spin_unlock_irq(&lock->wait_lock);
return 0;
}