linux-kernel - Re: [PATCH] NLM: Add lockd reference counting and clean up lockd startup and shutdown

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Date:	Thu, 13 Dec 2007 10:24:49 -0500
From:	Trond Myklebust <trond.myklebust@....uio.no>
To:	Jeff Layton <jlayton@...hat.com>
Cc:	Christoph Hellwig <hch@...radead.org>, linux-nfs@...r.kernel.org,
	nfsv4@...ux-nfs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] NLM: Add lockd reference counting and clean up lockd
	startup and shutdown


On Thu, 2007-12-13 at 09:40 -0500, Jeff Layton wrote:
> On Sat, 8 Dec 2007 14:07:47 +0000
> Christoph Hellwig <hch@...radead.org> wrote:
> 
> > > +	mutex_lock(&nlmsvc_mutex);
> > > +	while (atomic_read(&nlmsvc_ref) != 0) {
> > 
> > might be better to do the refcounting outside the thread and use the
> > kthread api, which is something we still need to do for lockd anyway.
> > 
> 
> I took a swipe at doing this, and have a set of patches that make lockd
> use kthreads. It works well, but there's a problem once I add in the
> reference counting.
> 
> In the situation that prompted this whole thing, the last nlmsvc_ref
> gets put by lockd itself. A kthread can't call kthread_stop on itself
> since it will deadlock.
> 
> Is there a way to gracefully allow a kthread to shut itself down?
> Alternately, I suppose I could schedule_work() the kthread_stop, though
> that seems sort of ugly...

How about just 'return'? :-)

You shouldn't need to signal yourself to stop.

Cheers
  Trond

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