linux-kernel - Re: [GIT PULL] dlm fix for 2.6.38

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Message-ID: <20110212155100.GR3770@htj.dyndns.org>
Date:	Sat, 12 Feb 2011 16:51:00 +0100
From:	Tejun Heo <tj@...nel.org>
To:	Steven Whitehouse <swhiteho@...hat.com>
Cc:	David Teigland <teigland@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [GIT PULL] dlm fix for 2.6.38

Hello,

On Sat, Feb 12, 2011 at 03:44:35PM +0000, Steven Whitehouse wrote:
> > diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
> > index 9c64ae9..2d8c87b 100644
> > --- a/fs/dlm/lowcomms.c
> > +++ b/fs/dlm/lowcomms.c
> > @@ -1468,15 +1468,13 @@ static void work_stop(void)
> >  
> >  static int work_start(void)
> >  {
> > -	recv_workqueue = alloc_workqueue("dlm_recv", WQ_MEM_RECLAIM |
> > -					 WQ_HIGHPRI | WQ_FREEZEABLE, 0);
> > +	recv_workqueue = create_singlethread_workqueue("dlm_recv");

recv_workqueue was multithread one even before the conversion.  It
probably is best to leave this part alone.

> > -	send_workqueue = alloc_workqueue("dlm_send", WQ_MEM_RECLAIM |
> > -					 WQ_HIGHPRI | WQ_FREEZEABLE, 0);
> > +	send_workqueue = create_singlethread_workqueue("dlm_send");

send_workqueue was converted from ST to MT but the correct way at this
point would be,

	alloc_ordered_workqueue("dlm_send",
				WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_FREEZEABLE);

> >  	if (!send_workqueue) {
> >  		log_print("can't start dlm_send");
> >  		destroy_workqueue(recv_workqueue);
> > 
> > 
> 
> What is the issue here? If there is a problem with the workqueues then
> we should ask Tejun about it,

Yeah, what kind of problem was it?  There's only one work per
connection so reordering is not a problem.  All the workqueue
operations use proper locking, so the conversion seemed safe to me.
What am I missing?

Thanks.

-- 
tejun
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