From: Matthew Wilcox <willy@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Davidlohr Bueso <dave@stgolabs.net>,
"Theodore Y. Ts'o" <tytso@mit.edu>,
Oleg Nesterov <oleg@redhat.com>,
Amir Goldstein <amir73il@gmail.com>, Jan Kara <jack@suse.cz>
Subject: Re: [PATCH v4 1/2] locking/rwsem: Add a new RWSEM_ANONYMOUSLY_OWNED flag
Date: Wed, 16 May 2018 05:19:47 -0700 [thread overview]
Message-ID: <20180516121947.GE20670@bombadil.infradead.org> (raw)
In-Reply-To: <1526420991-21213-2-git-send-email-longman@redhat.com>
On Tue, May 15, 2018 at 05:49:50PM -0400, Waiman Long wrote:
> @@ -357,11 +357,8 @@ static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem)
>
> rcu_read_lock();
> owner = READ_ONCE(sem->owner);
> - if (!rwsem_owner_is_writer(owner)) {
> - /*
> - * Don't spin if the rwsem is readers owned.
> - */
> - ret = !rwsem_owner_is_reader(owner);
> + if (!owner || !is_rwsem_owner_spinnable(owner)) {
> + ret = !owner; /* !owner is spinnable */
> goto done;
> }
This is confusingly written. I think you mean ...
if (!owner)
goto done;
if (!is_rwsem_owner_spinnable(owner)) {
ret = false;
goto done;
}
next prev parent reply other threads:[~2018-05-16 12:19 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-15 21:49 [PATCH v4 0/2] locking/rwsem: Fix DEBUG_RWSEM warning from thaw_super() Waiman Long
2018-05-15 21:49 ` [PATCH v4 1/2] locking/rwsem: Add a new RWSEM_ANONYMOUSLY_OWNED flag Waiman Long
2018-05-16 10:48 ` Oleg Nesterov
2018-05-16 11:59 ` Peter Zijlstra
2018-05-16 13:11 ` Waiman Long
2018-05-16 15:27 ` Oleg Nesterov
2018-05-16 12:19 ` Matthew Wilcox [this message]
2018-05-18 7:02 ` Ingo Molnar
2018-05-18 8:41 ` Oleg Nesterov
2018-05-18 9:40 ` Ingo Molnar
2018-05-18 16:55 ` [PATCH] locking/rwsem: simplify the is-owner-spinnable checks Oleg Nesterov
2018-05-18 17:00 ` Waiman Long
2018-05-15 21:49 ` [PATCH v4 2/2] locking/percpu-rwsem: Annotate rwsem ownership transfer by setting RWSEM_OWNER_UNKNOWN Waiman Long
2018-05-16 5:37 ` Amir Goldstein
2018-05-16 13:17 ` Waiman Long
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