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From: Jason Baron <jbaron@akamai.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: waitqueue lockdep annotation
Date: Fri, 1 Dec 2017 17:34:50 -0500	[thread overview]
Message-ID: <2fd9dc6b-9201-67db-b81e-a783daf0ce50@akamai.com> (raw)
In-Reply-To: <20171201220239.GA32542@lst.de>

On 12/01/2017 05:02 PM, Christoph Hellwig wrote:
> On Fri, Dec 01, 2017 at 02:00:33PM -0500, Jason Baron wrote:
>> You could leave the annotation and do something like:
>> s/ep->lock/ep->wq->lock. And then that would remove the ep->lock saving
>> a bit of space.
> 
> Looks like this isn't going to work due to ep_poll_safewake taking
> another waitqueue lock.  If we had a strict lock order it might work,
> but the mess in ep_call_nested makes me fear it doesn't.
> 

hmmm...I'm not sure how this suggestion would change the locking rules
from what we currently have. Right now, we use ep->lock, if we remove
that and use ep->wq->lock instead, there is just a 1-to-1 mapping there
that has not changed, since ep->wq->lock currently is completely not
being used.

Thanks,

-Jason

  reply	other threads:[~2017-12-01 22:35 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-30 14:20 waitqueue lockdep annotation Christoph Hellwig
2017-11-30 14:20 ` [PATCH 1/2] sched/wait: assert the wait_queue_head lock is held in __wake_up_common Christoph Hellwig
2017-11-30 14:20 ` [PATCH 2/2] epoll: use proper wake_up variant in ep_poll_callback Christoph Hellwig
2017-11-30 20:50 ` waitqueue lockdep annotation Andrew Morton
2017-11-30 21:38   ` Jason Baron
2017-11-30 22:11     ` Christoph Hellwig
2017-11-30 22:18       ` Jason Baron
2017-12-01 17:11         ` Christoph Hellwig
2017-12-01 19:00           ` Jason Baron
2017-12-01 22:02             ` Christoph Hellwig
2017-12-01 22:34               ` Jason Baron [this message]
2017-12-01 23:03                 ` Christoph Hellwig
2017-12-05 15:24                   ` Jason Baron
2017-12-05 15:36                     ` Davidlohr Bueso
2017-12-06 23:51                     ` Christoph Hellwig
2017-12-06 23:52 Christoph Hellwig

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