From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Mike Galbraith <efault@gmx.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
linux-rt-users <linux-rt-users@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [patch-rt] locking, rwlock-rt: do not save state multiple times in __write_rt_lock()
Date: Fri, 18 Aug 2017 11:06:27 +0200 [thread overview]
Message-ID: <20170818090626.5u5tm3hakhhntx5y@linutronix.de> (raw)
In-Reply-To: <1502280288.6441.3.camel@gmx.de>
On 2017-08-09 14:04:48 [+0200], Mike Galbraith wrote:
>
> Save state prior to entering the acquisition loop, otherwise we may
> initially see readers, but upon releasing ->wait_lock see none, loop
> back around, and having not slept, save TASK_UNINTERRUPTIBLE.
>
> Signed-off-by_ Mike Galbraith <efault@gmx.de>
applied but
> ---
> kernel/locking/rwlock-rt.c | 37 ++++++++++++++++++++-----------------
> 1 file changed, 20 insertions(+), 17 deletions(-)
>
> --- a/kernel/locking/rwlock-rt.c
> +++ b/kernel/locking/rwlock-rt.c
> @@ -190,30 +190,33 @@ void __sched __write_rt_lock(struct rt_r
…
>
> + for (;;) {
> /* Have all readers left the critical region? */
> - if (!atomic_read(&lock->readers)) {
> - atomic_set(&lock->readers, WRITER_BIAS);
> - raw_spin_lock(&self->pi_lock);
> - __set_current_state_no_track(self->saved_state);
> - self->saved_state = TASK_RUNNING;
> - raw_spin_unlock(&self->pi_lock);
> - raw_spin_unlock_irqrestore(&m->wait_lock, flags);
> - return;
I kept this part where it is so the diff is smaller.
> - }
> + if (!atomic_read(&lock->readers))
> + break;
> }
>
> int __write_rt_trylock(struct rt_rw_lock *lock)
Sebastian
next prev parent reply other threads:[~2017-08-18 9:06 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-04 17:38 [ANNOUNCE] v4.11.12-rt9 Sebastian Andrzej Siewior
2017-08-05 6:13 ` Mike Galbraith
2017-08-05 14:57 ` Mike Galbraith
2017-08-07 7:33 ` Sebastian Andrzej Siewior
2017-08-07 8:22 ` Mike Galbraith
2017-08-08 10:00 ` Mike Galbraith
2017-08-11 7:55 ` [patch-rt] hotplug, hrtimer: Migrate expired/deferred timers during cpu offline Mike Galbraith
2017-08-11 8:15 ` Mike Galbraith
2017-08-14 7:59 ` Mike Galbraith
2017-08-17 16:50 ` Sebastian Andrzej Siewior
2017-08-17 17:17 ` Sebastian Andrzej Siewior
2017-08-17 17:26 ` Mike Galbraith
2017-08-17 17:37 ` Mike Galbraith
2017-08-17 18:43 ` Mike Galbraith
2017-08-07 7:52 ` [ANNOUNCE] v4.11.12-rt9 Sebastian Andrzej Siewior
2017-08-07 8:38 ` Mike Galbraith
2017-08-09 12:04 ` [patch-rt] locking, rwlock-rt: do not save state multiple times in __write_rt_lock() Mike Galbraith
2017-08-18 9:06 ` Sebastian Andrzej Siewior [this message]
2017-08-07 9:10 ` [ANNOUNCE] v4.11.12-rt9 Mike Galbraith
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