linux-kernel - Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops

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Message-ID: <20170817173004.263d2891@gandalf.local.home>
Date:   Thu, 17 Aug 2017 17:30:04 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Waiman Long <longman@...hat.com>
Cc:     Jens Axboe <axboe@...nel.dk>,
        Jeff Layton <jlayton@...chiereds.net>,
        "J. Bruce Fields" <bfields@...ldses.org>,
        Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
        linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v2] blktrace: Fix potentail deadlock between delete &
 sysfs ops

On Thu, 17 Aug 2017 17:10:07 -0400
Steven Rostedt <rostedt@...dmis.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 is
> 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