From: Joel Fernandes <joel@joelfernandes.org>
To: Waiman Long <longman@redhat.com>
Cc: Connor O'Brien <connoro@google.com>,
linux-kernel@vger.kernel.org, kernel-team@android.com,
John Stultz <jstultz@google.com>,
Qais Yousef <qais.yousef@arm.com>, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Valentin Schneider <vschneid@redhat.com>,
Will Deacon <will@kernel.org>, Boqun Feng <boqun.feng@gmail.com>,
"Paul E . McKenney" <paulmck@kernel.org>
Subject: Re: [RFC PATCH 01/11] locking/ww_mutex: Remove wakeups from under mutex::wait_lock
Date: Wed, 12 Oct 2022 23:54:56 +0000 [thread overview]
Message-ID: <Y0dT0D3d/07mNHAK@google.com> (raw)
In-Reply-To: <73859883-78c4-1080-7846-e8d644ad397a@redhat.com>
On Tue, Oct 04, 2022 at 12:01:13PM -0400, Waiman Long wrote:
> On 10/3/22 17:44, Connor O'Brien wrote:
> > diff --git a/kernel/locking/ww_mutex.h b/kernel/locking/ww_mutex.h
> > index 56f139201f24..dfc174cd96c6 100644
> > --- a/kernel/locking/ww_mutex.h
> > +++ b/kernel/locking/ww_mutex.h
> > @@ -161,6 +161,11 @@ static inline void lockdep_assert_wait_lock_held(struct rt_mutex *lock)
> > #endif /* WW_RT */
> > +void ww_ctx_wake(struct ww_acquire_ctx *ww_ctx)
> > +{
> > + wake_up_q(&ww_ctx->wake_q);
> > +}
> > +
> > /*
> > * Wait-Die:
> > * The newer transactions are killed when:
> > @@ -284,7 +289,7 @@ __ww_mutex_die(struct MUTEX *lock, struct MUTEX_WAITER *waiter,
> > #ifndef WW_RT
> > debug_mutex_wake_waiter(lock, waiter);
> > #endif
> > - wake_up_process(waiter->task);
> > + wake_q_add(&ww_ctx->wake_q, waiter->task);
> > }
> > return true;
> > @@ -331,7 +336,7 @@ static bool __ww_mutex_wound(struct MUTEX *lock,
> > * wakeup pending to re-read the wounded state.
> > */
> > if (owner != current)
> > - wake_up_process(owner);
> > + wake_q_add(&ww_ctx->wake_q, owner);
> > return true;
> > }
> > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> > index ee28253c9ac0..617e737392be 100644
> > --- a/kernel/sched/core.c
> > +++ b/kernel/sched/core.c
> > @@ -1013,6 +1013,13 @@ void wake_up_q(struct wake_q_head *head)
> > wake_up_process(task);
> > put_task_struct(task);
> > }
> > + /*
> > + * XXX connoro: seems this is needed now that ww_ctx_wake() passes in a
> > + * wake_q_head that is embedded in struct ww_acquire_ctx rather than
> > + * declared locally.
> > + */
> > + head->first = node;
> > + head->lastp = &head->first;
> > }
>
> You shouldn't do wake_q_init() here in wake_up_q(). Instead, you should do
> it in ww_ctx_wake() right after the wake_up_q() call.
> :
Exactly, it is also mentioned in the wake_q.h header:
* The DEFINE_WAKE_Q macro declares and initializes the list head.
* wake_up_q() does NOT reinitialize the list; it's expected to be
* called near the end of a function. Otherwise, the list can be
* re-initialized for later re-use by wake_q_init().
*
Thanks.
next prev parent reply other threads:[~2022-10-12 23:55 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-03 21:44 [RFC PATCH 00/11] Reviving the Proxy Execution Series Connor O'Brien
2022-10-03 21:44 ` [RFC PATCH 01/11] locking/ww_mutex: Remove wakeups from under mutex::wait_lock Connor O'Brien
2022-10-04 16:01 ` Waiman Long
2022-10-12 23:54 ` Joel Fernandes [this message]
2022-10-20 18:43 ` Connor O'Brien
2022-10-03 21:44 ` [RFC PATCH 02/11] locking/mutex: Rework task_struct::blocked_on Connor O'Brien
2022-10-03 21:44 ` [RFC PATCH 03/11] kernel/locking: Add p->blocked_on wrapper Connor O'Brien
2022-10-03 21:44 ` [RFC PATCH 04/11] locking/mutex: make mutex::wait_lock irq safe Connor O'Brien
2022-10-13 4:30 ` Joel Fernandes
2022-10-03 21:44 ` [RFC PATCH 05/11] sched: Split scheduler execution context Connor O'Brien
2022-10-14 17:01 ` Joel Fernandes
2022-10-19 17:17 ` Valentin Schneider
2022-10-20 18:43 ` Connor O'Brien
2022-10-03 21:44 ` [RFC PATCH 06/11] kernel/locking: Expose mutex_owner() Connor O'Brien
2022-10-03 21:44 ` [RFC PATCH 07/11] sched: Add proxy execution Connor O'Brien
2022-10-12 1:54 ` Joel Fernandes
2022-10-12 9:46 ` Juri Lelli
2022-10-14 17:07 ` Joel Fernandes
2022-10-15 13:53 ` Peter Zijlstra
2022-10-16 20:48 ` Steven Rostedt
2022-10-17 4:03 ` Joel Fernandes
2022-10-17 7:26 ` Peter Zijlstra
2022-10-24 22:33 ` Qais Yousef
2022-10-25 11:19 ` Joel Fernandes
2022-10-25 22:10 ` Qais Yousef
2022-10-15 15:28 ` Peter Zijlstra
2022-10-15 15:08 ` Peter Zijlstra
2022-10-15 15:10 ` Peter Zijlstra
2022-10-15 15:47 ` Peter Zijlstra
2022-10-24 10:13 ` Dietmar Eggemann
2022-10-29 3:31 ` Joel Fernandes
2022-10-31 16:39 ` Dietmar Eggemann
2022-10-31 18:00 ` Joel Fernandes
2022-11-04 17:09 ` Dietmar Eggemann
2022-11-21 0:22 ` Joel Fernandes
2022-11-21 1:49 ` Joel Fernandes
2022-11-21 3:59 ` Joel Fernandes
2022-11-22 18:45 ` Joel Fernandes
2023-01-09 8:51 ` Chen Yu
2022-10-03 21:44 ` [RFC PATCH 08/11] sched: Fixup task CPUs for potential proxies Connor O'Brien
2022-10-03 21:44 ` [RFC PATCH 09/11] sched/rt: Fix proxy/current (push,pull)ability Connor O'Brien
2022-10-10 11:40 ` Valentin Schneider
2022-10-14 22:32 ` Connor O'Brien
2022-10-19 17:05 ` Valentin Schneider
2022-10-20 13:30 ` Juri Lelli
2022-10-20 16:14 ` Valentin Schneider
2022-10-21 2:22 ` Connor O'Brien
2022-10-03 21:45 ` [RFC PATCH 10/11] torture: support randomized shuffling for proxy exec testing Connor O'Brien
2022-11-12 16:54 ` Joel Fernandes
2022-11-14 20:44 ` Connor O'Brien
2022-11-15 16:02 ` Joel Fernandes
2022-10-03 21:45 ` [RFC PATCH 11/11] locktorture: support nested mutexes Connor O'Brien
2022-10-06 9:59 ` [RFC PATCH 00/11] Reviving the Proxy Execution Series Juri Lelli
2022-10-06 10:07 ` Peter Zijlstra
2022-10-06 12:14 ` Juri Lelli
2022-10-15 15:44 ` Peter Zijlstra
2022-10-17 2:23 ` Joel Fernandes
2022-10-19 11:43 ` Qais Yousef
2022-10-19 12:23 ` Joel Fernandes
2022-10-19 13:41 ` Juri Lelli
2022-10-19 13:51 ` Joel Fernandes
2022-10-19 19:30 ` Qais Yousef
2022-10-20 8:51 ` Joel Fernandes
2022-10-17 3:25 ` Chengming Zhou
2022-10-17 3:56 ` Joel Fernandes
2022-10-17 4:26 ` Chengming Zhou
2022-10-17 12:27 ` Joel Fernandes
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