lkml.org 
[lkml]   [2014]   [Mar]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH] cifs: Fix possible deadlock with cifs and work queues
On Fri, 21 Mar 2014 08:17:06 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Fri, 21 Mar 2014 12:32:12 +0400
> Pavel Shilovsky <piastry@etersoft.ru> wrote:
>
>
> > Read and write codepaths both obtain lock_sem for read and then wait
> > for cifsiod_wq to complete and release lock_sem. They don't do any
> > lock_sem operations inside their work task queued to cifsiod_wq. But
> > oplock code can obtain/release lock_sem in its work task. So, that's
> > why I agree with Jeff and suggest to move the oplock code to a
> > different work queue (cifsioopd_wq?) but leave read and write
> > codepaths use cifsiod_wq.
>
> OK, how about I submit a second patch that moves the reader and writer
> to its own "safe" workqueue?
>
> -- Steve
>

That'd probably work fine too. The main point is to make sure oplock
breaks run on a different workqueue from where read or write completion
jobs run since they are operating on the lock_sem. The other jobs that
get queued to cifsiod_wq don't touch the lock_sem and shouldn't be a
problem.

--
Jeff Layton <jlayton@redhat.com>


\
 
 \ /
  Last update: 2014-03-21 14:21    [W:0.077 / U:47.548 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site