From: Peter Zijlstra <peterz@infradead.org>
To: Jan Stancek <jstancek@redhat.com>
Cc: Will Deacon <will@kernel.org>, Waiman Long <longman@redhat.com>,
linux-kernel@vger.kernel.org, dbueso@suse.de, mingo@redhat.com,
jade alglave <jade.alglave@arm.com>,
paulmck@linux.vnet.ibm.com
Subject: Re: [PATCH v2] locking/rwsem: add acquire barrier to read_slowpath exit when queue is empty
Date: Thu, 18 Jul 2019 13:09:28 +0200 [thread overview]
Message-ID: <20190718110928.GT3463@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190718110446.GC3419@hirez.programming.kicks-ass.net>
It's simpler like so:
On Thu, Jul 18, 2019 at 01:04:46PM +0200, Peter Zijlstra wrote:
> X = 0;
>
> rwsem_down_read()
> for (;;) {
> set_current_state(TASK_UNINTERRUPTIBLE);
>
> X = 1;
> rwsem_up_write();
> rwsem_mark_wake()
> atomic_long_add(adjustment, &sem->count);
> smp_store_release(&waiter->task, NULL);
>
> if (!waiter.task)
> break;
>
> ...
> }
>
> r = X;
>
next prev parent reply other threads:[~2019-07-18 11:09 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-16 16:04 [PATCH] locking/rwsem: use read_acquire in read_slowpath exit when queue is empty Jan Stancek
2019-07-16 16:53 ` Waiman Long
2019-07-16 18:34 ` Jan Stancek
2019-07-16 18:58 ` Peter Zijlstra
2019-07-16 19:09 ` Waiman Long
2019-07-17 12:02 ` [PATCH v2] locking/rwsem: add acquire barrier to " Jan Stancek
2019-07-17 13:13 ` Will Deacon
2019-07-17 14:19 ` Waiman Long
2019-07-17 19:22 ` Jan Stancek
2019-07-17 19:39 ` Waiman Long
2019-07-18 8:51 ` [PATCH v3] " Jan Stancek
2019-07-25 16:00 ` [tip:locking/core] locking/rwsem: Add missing ACQUIRE " tip-bot for Jan Stancek
2019-07-18 9:26 ` [PATCH v2] locking/rwsem: add acquire barrier " Will Deacon
2019-07-18 10:50 ` Jan Stancek
2019-07-18 11:04 ` Peter Zijlstra
2019-07-18 11:09 ` Peter Zijlstra [this message]
2019-07-18 11:36 ` Jan Stancek
2019-07-18 12:12 ` Paul E. McKenney
2019-07-18 10:58 ` Peter Zijlstra
2019-07-18 11:45 ` Will Deacon
2019-07-18 12:23 ` Peter Zijlstra
2019-07-17 15:33 ` Waiman Long
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