[Ocfs2-devel] FW: [PATCH] workqueue: cancel_delayed_work() should return %NULL if work item is idle

[Dan Magenheimer]

> From: Joel Becker [mailto:jlbec at evilplan.org]
> Sent: Tuesday, October 23, 2012 2:51 AM
> To: Dan Magenheimer
> Cc: ocfs2-devel at oss.oracle.com
> Subject: Re: [Ocfs2-devel] FW: [PATCH] workqueue: cancel_delayed_work() should return %NULL if work
> item is idle
> 
> Help me understand the issue.  Who broke this?  Do I need to push this
> patch, or is someone else?

Tejun's new workqueue implementation which was just merged in 3.7
had a bug in it.  See this thread:

https://lkml.org/lkml/2012/10/18/592 

It appears the patch didn't get into 3.7-rc2.  Cc'ing Tejun.
Hopefully it will be merged for -rc3 since
ramster is completely broken without the patch because a reference
counter on a socket gets miscounted.  I expect the same to be
true of ocfs2... Srini was going to check.

Dan

> On Fri, Oct 19, 2012 at 10:56:42AM -0700, Dan Magenheimer wrote:
> > FYI, it is likely that ocfs2 will not work on 3.7-rcN until
> > the following one-line patch is merged, as the code in ramster
> > that provoked it is directly leveraged from ocfs2 o2net.
> >
> > > From: Tejun Heo [mailto:tj at kernel.org]
> > > Sent: Thursday, October 18, 2012 5:39 PM
> > > To: Dan Magenheimer
> > > Cc: linux-kernel at vger.kernel.org; Konrad Wilk
> > > Subject: [PATCH] workqueue: cancel_delayed_work() should return %NULL if work item is idle
> > >
> > > From e65120fcfc1cb9697655d29ecd7982451c05d3c2 Mon Sep 17 00:00:00 2001
> > > From: Dan Magenheimer <dan.magenheimer at oracle.com>
> > > Date: Thu, 18 Oct 2012 16:31:37 -0700
> > >
> > > 57b30ae77b ("workqueue: reimplement cancel_delayed_work() using
> > > try_to_grab_pending()") made cancel_delayed_work() always return %true
> > > unless someone else is also trying to cancel the work item, which is
> > > broken - if the target work item is idle, the return value should be
> > > %false.
> > >
> > > try_to_grab_pending() indicates that the target work item was idle by
> > > zero return value.  Use it for return.  Note that this brings
> > > cancel_delayed_work() in line with __cancel_work_timer() in return
> > > value handling.
> > >
> > > Signed-off-by: Dan Magenheimer <dan.magenheimer at oracle.com>
> > > Signed-off-by: Tejun Heo <tj at kernel.org>
> > > LKML-Reference: <444a6439-b1a4-4740-9e7e-bc37267cfe73 at default>
> > > ---
> > >  kernel/workqueue.c |    2 +-
> > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > >
> > > diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> > > index d951daa..042d221 100644
> > > --- a/kernel/workqueue.c
> > > +++ b/kernel/workqueue.c
> > > @@ -2982,7 +2982,7 @@ bool cancel_delayed_work(struct delayed_work *dwork)
> > >
> > >  	set_work_cpu_and_clear_pending(&dwork->work, work_cpu(&dwork->work));
> > >  	local_irq_restore(flags);
> > > -	return true;
> > > +	return ret;
> > >  }
> > >  EXPORT_SYMBOL(cancel_delayed_work);
> > >
> > > --
> > > 1.7.7.3
> > >
> >
> > _______________________________________________
> > Ocfs2-devel mailing list
> > Ocfs2-devel at oss.oracle.com
> > https://oss.oracle.com/mailman/listinfo/ocfs2-devel
> 
> --
> 
> Life's Little Instruction Book #139
> 
> 	"Never deprive someone of hope; it might be all they have."
> 
> 			http://www.jlbec.org/
> 			jlbec at evilplan.org