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

[Waiman Long]

On 08/17/2017 05:30 PM, Steven Rostedt wrote:
> On Thu, 17 Aug 2017 17:10:07 -0400
> Steven Rostedt <rostedt@xxxxxxxxxxx> 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

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