From: Amit Shah <amit.shah@redhat.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Virtualization List <virtualization@lists.linux-foundation.org>,
miche@google.com, "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH 1/2] virtio: console: Serialise control work
Date: Mon, 9 Jan 2012 09:23:53 +0530 [thread overview]
Message-ID: <20120109035353.GC29012@amit.redhat.com> (raw)
In-Reply-To: <87lipha9k8.fsf@rustcorp.com.au>
On (Mon) 09 Jan 2012 [13:03:59], Rusty Russell wrote:
> On Fri, 6 Jan 2012 16:19:07 +0530, Amit Shah <amit.shah@redhat.com> wrote:
> > We currently allow multiple instances of the control work handler to run
> > in parallel. This isn't expected to work; serialise access by disabling
> > interrupts on new packets from the Host and enable them when all the
> > existing ones are consumed.
> >
> > Testcase: hot-plug/unplug a port in a loop. Without this patch, some
> > sysfs warnings are seen along with freezes. With the patch, all works
> > fine.
>
> Wait a sec... This might *work*, but it's not correct. Remember that
> disabling callbacks is a hint, and it's cetainly not synchronous.
>
> You need something else to explicitly prevent reentry.
OK, right. I'll use the nrt workqueue to synchronise then.
Amit
next prev parent reply other threads:[~2012-01-09 3:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-06 10:49 [PATCH 0/2] virtio: console: control queue race fixes Amit Shah
2012-01-06 10:49 ` [PATCH 1/2] virtio: console: Serialise control work Amit Shah
2012-01-09 2:33 ` Rusty Russell
2012-01-09 3:53 ` Amit Shah [this message]
2012-01-06 10:49 ` [PATCH 2/2] virtio: console: Disable callbacks for virtqueues at start of S4 freeze Amit Shah
2012-01-09 2:31 ` [PATCH 0/2] virtio: console: control queue race fixes Rusty Russell
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