From mboxrd@z Thu Jan  1 00:00:00 1970
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Subject: Re: [PATCH v2] blktrace: Fix potentail deadlock between delete &
 sysfs ops
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Jens Axboe <axboe@kernel.dk>, Jeff Layton <jlayton@poochiereds.net>,
 "J. Bruce Fields" <bfields@fieldses.org>, Ingo Molnar <mingo@kernel.org>,
 linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
 linux-fsdevel@vger.kernel.org
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From: Waiman Long <longman@redhat.com>
Message-ID: <5a5d0743-d2db-89c8-59cc-542835baeccf@redhat.com>
Date: Fri, 18 Aug 2017 09:55:58 -0400
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On 08/17/2017 05:30 PM, Steven Rostedt wrote:
> On Thu, 17 Aug 2017 17:10:07 -0400
> Steven Rostedt <rostedt@goodmis.org> wrote:
>
>
>> Instead of playing games with taking the lock, the only way this race
>> is hit, is if the partition is being deleted and the sysfs attribute i=
s
>> being read at the same time, correct? In that case, just return
>> -ENODEV, and be done with it.
> Nevermind that wont work. Too bad there's not a mutex_lock_timeout()
> that we could use in a loop. It would solve the issue of forward
> progress with RT tasks, and will break after a timeout in case of
> deadlock.
>
> -- Steve

I think it will be useful to have mutex_timed_lock(). RT-mutex does have
a timed version, so I guess it shouldn't be hard to implement one for
mutex. I can take a shot at trying to do that.

Thanks,
Longman