From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH RFC] virtio_net: fix refill related races
Date: Tue, 13 Dec 2011 13:05:11 +1030
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References: <20111207152120.GA23417@redhat.com>
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Amit Shah <amit.shah@redhat.com>, netdev@vger.kernel.org, Tejun Heo <tj@kernel.org>, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org
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On Mon, 12 Dec 2011 13:54:06 +0200, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> On Mon, Dec 12, 2011 at 09:25:07AM +1030, Rusty Russell wrote:
> > Orthogonally, the refill-stop code is still buggy, as you noted.
> 
> Sorry I don't understand how it's still buggy.

Both places where we call:

	cancel_delayed_work_sync(&vi->refill);

Do not actually guarantee that vi->refill isn't running, because it
can requeue itself.  A 'bool no_more_refill' field seems like the
simplest fix for this, but I don't think it's sufficient.

Tejun, is this correct?  What's the correct way to synchronously stop a
delayed_work which can "schedule_delayed_work(&vi->refill, HZ/2);" on
itself?

Thanks,
Rusty.