Re: [PATCH v3 7/7] locking/rtmutex: Acquire the hb lock via trylock after wait-proxylock.

[Jiri Slaby]

On 15. 01. 24, 19:33, Sebastian Andrzej Siewior wrote:
> This duct tape at the end waits until the pi-state leaves or we get a
> waiter. So this works but is not a fix.

FWIW, it indeed avoids the problem.

> --- a/kernel/futex/pi.c
> +++ b/kernel/futex/pi.c
> @@ -1182,6 +1182,9 @@ int futex_unlock_pi(u32 __user *uaddr, unsigned int flags)
>   		rt_waiter = rt_mutex_top_waiter(&pi_state->pi_mutex);
>   		if (!rt_waiter) {
>   			raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
> +			spin_unlock(&hb->lock);
> +			cpu_relax();
> +			goto retry;
>   			goto do_uncontended;
>   		}

thanks,
--
js
suse labs