From: Ingo Molnar <mingo@kernel.org>
To: Andreas Dilger <adilger@dilger.ca>
Cc: Christoph Hellwig <hch@lst.de>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Jason Baron <jbaron@akamai.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] epoll: use the waitqueue lock to protect ep->wq
Date: Thu, 7 Dec 2017 07:12:13 +0100 [thread overview]
Message-ID: <20171207061213.nhm4p5pghfsglkgy@gmail.com> (raw)
In-Reply-To: <7AFB0C38-3D2E-45E8-9092-CA424BFD32B6@dilger.ca>
* Andreas Dilger <adilger@dilger.ca> wrote:
> > On Dec 6, 2017, at 17:49, Ingo Molnar <mingo@kernel.org> wrote:
> >
> > This exposes some waitqueue internals, but AFAICS the FUSE code already does a
> > similar trick with fiq->waitq.lock so there's precedent.
>
> What about waitqueue_lock() and waitqueue_unlock() helpers that
> lock and unlock, to avoid exposing the internals? Or would that add
> confusion by making users think they need their own waitqueue locking?
Right now there are just two users (FUSE and epoll), and both are well-maintained,
essentially core kernel code - I'd rather prefer the readability of explicitly
writing out the locking/unlocking pattern.
So while it's a mild layering violation, it's also a valid looking optimization.
Thanks,
Ingo
next prev parent reply other threads:[~2017-12-07 6:12 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-06 23:52 waitqueue lockdep annotation Christoph Hellwig
2017-12-06 23:52 ` [PATCH 1/2] epoll: use the waitqueue lock to protect ep->wq Christoph Hellwig
2017-12-07 0:49 ` Ingo Molnar
2017-12-07 2:38 ` Andreas Dilger
2017-12-07 6:12 ` Ingo Molnar [this message]
2017-12-14 13:06 ` Christoph Hellwig
2017-12-07 16:09 ` Jason Baron
2017-12-14 13:05 ` Christoph Hellwig
2017-12-06 23:52 ` [PATCH 2/2] sched/wait: assert the wait_queue_head lock is held in __wake_up_common Christoph Hellwig
2017-12-07 0:50 ` Ingo Molnar
2017-12-14 13:08 ` Christoph Hellwig
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