From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>,
kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
virtualization@lists.linux-foundation.org, khoa@us.ibm.com,
Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH v2] virtio_blk: unlock vblk->lock during kick
Date: Mon, 04 Jun 2012 08:02:16 +0200 [thread overview]
Message-ID: <4FCC4F68.4020304@de.ibm.com> (raw)
In-Reply-To: <877gvn3kks.fsf@rustcorp.com.au>
On 04/06/12 03:57, Rusty Russell wrote:
> Unfortunately, this conflicts with Asias He's deadlock fix, which has
> us just using the block-layer-supplied spinlock.
>
> If we drop the lock around the kick as you suggest, we're playing with
> fire. All the virtio backends have an atomic notify, so they're OK,
> and the block layer *looks* safe at a glance, but there's no assurances.
Well, the kick itself returns early, but in the host every other action
is already asynchronously running - not caring about the guest locks at all.
So if removing the lock around the kick causes a problem, then the problem
is already present, no?
Christian
next prev parent reply other threads:[~2012-06-04 6:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1338383963-17910-1-git-send-email-stefanha@linux.vnet.ibm.com>
2012-05-30 13:39 ` [PATCH v2] virtio_blk: unlock vblk->lock during kick Christian Borntraeger
2012-06-04 1:57 ` Rusty Russell
2012-06-04 5:29 ` Michael S. Tsirkin
2012-06-04 6:02 ` Christian Borntraeger [this message]
2012-06-04 8:27 ` Stefan Hajnoczi
2012-06-04 8:35 ` Asias He
2012-06-04 8:57 ` Asias He
2012-06-01 4:38 ` Asias He
2012-06-01 7:58 ` Stefan Hajnoczi
2012-05-30 13:19 Stefan Hajnoczi
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