From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Jan Beulich" <JBeulich@novell.com>
Subject: Re: [PATCH linux-2.6.18-xen] fix
	xenbus_transaction_start() hang caused by double
	xenbus_transaction_end()
Date: Fri, 13 May 2011 09:15:00 +0100
Message-ID: <4DCD04A402000078000412DD@vpn.id2.novell.com>
References: <4DCBB551.7000002@redhat.com>
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To: Laszlo Ersek <lersek@redhat.com>
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List-Id: xen-devel@lists.xenproject.org

>>> On 12.05.11 at 12:24, Laszlo Ersek <lersek@redhat.com> wrote:
> fix xenbus_transaction_start() hang caused by double xenbus_transaction_e=
nd()
>=20
> vbd_resize() up_read()'s xs_state.suspend_mutex twice in a row via =
double
> xenbus_transaction_end() calls. The next down_read() in
> xenbus_transaction_start() (at eg. the next resize attempt) hangs.
>=20
> See RHBZ#618317.
>=20
> Thanks for considering.
>=20
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>

Acked-by: Jan Beulich <jbeulich@novell.com>

(I wonder how this ever passed any testing.)

The same would be needed for pv-ops too afaics.

Jan

> ---
>  drivers/xen/blkback/vbd.c |    1 +
>  1 file changed, 1 insertion(+)
>=20
> diff --git a/drivers/xen/blkback/vbd.c b/drivers/xen/blkback/vbd.c
> --- a/drivers/xen/blkback/vbd.c
> +++ b/drivers/xen/blkback/vbd.c
> @@ -156,6 +156,7 @@
>  		goto again;
>  	if (err)
>  		printk(KERN_WARNING "Error ending transaction");
> +	return;
>  abort:
>  	xenbus_transaction_end(xbt, 1);
>  }
>=20
>=20
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