linux-kernel - Re: [PATCH v3] blktrace: Fix potentail deadlock between delete & sysfs ops

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Message-ID: <e7767695-e0b3-17d5-f54e-88b9cf170e60@redhat.com>
Date:   Fri, 18 Aug 2017 15:55:13 -0400
From:   Waiman Long <longman@...hat.com>
To:     Bart Van Assche <Bart.VanAssche@....com>,
        "mingo@...nel.org" <mingo@...nel.org>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "axboe@...nel.dk" <axboe@...nel.dk>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>
Subject: Re: [PATCH v3] blktrace: Fix potentail deadlock between delete &
 sysfs ops

On 08/18/2017 02:07 PM, Bart Van Assche wrote:
> On Fri, 2017-08-18 at 13:54 -0400, Waiman Long wrote:
>> Instead, a global blktrace
>> mutex will be used to serialize the read/write of the blktrace sysfs
>> attributes.
> Hello Waiman,
>
> Using a mutex to serialize code is wrong. What is needed is exact
> documentation of what data structures and/or member variables are
> protected by bdev->bd_mutex and by blktrace_mutex.

Yes, I missed the blk_trace_ioctl(). I should have modified it to use
blktrace_mutex as well.

> Also, please spell "potential" correctly in the subject of this patch.

Will do.

Thanks,
Longman