Messages in this thread Patch in this message | | | Date | Wed, 16 Aug 2023 17:22:31 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 0/6] locking/rtmutex: Avoid PI state recursion through sched_submit_work() |
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On Wed, Aug 16, 2023 at 04:58:18PM +0200, Peter Zijlstra wrote:
> I've ended up with the below, but it is quite horrible.. but let me go > stare at the futex wreckage before trying to clean things up.
OK, I think the below covers the simple case, now lets see if I can make sense of futex_wait_requeue_pi()... :/
--- --- a/kernel/futex/pi.c +++ b/kernel/futex/pi.c @@ -1002,6 +1002,12 @@ int futex_lock_pi(u32 __user *uaddr, uns goto no_block; } + /* + * Must be done before we enqueue the waiter, here is unfortunately + * under the hb lock, but that *should* work. + */ + rt_mutex_pre_schedule(); + rt_mutex_init_waiter(&rt_waiter); /* @@ -1052,6 +1058,10 @@ int futex_lock_pi(u32 __user *uaddr, uns if (ret && !rt_mutex_cleanup_proxy_lock(&q.pi_state->pi_mutex, &rt_waiter)) ret = 0; + /* + * Waiter is unqueued. + */ + rt_mutex_post_schedule(); no_block: /* * Fixup the pi_state owner and possibly acquire the lock if we
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