From mboxrd@z Thu Jan  1 00:00:00 1970
From: aq <aquynh@gmail.com>
Subject: Re: [PATCH] Convert balloon driver to xenstore
Date: Wed, 3 Aug 2005 17:02:09 +0900
Message-ID: <9cde8bff05080301022cf0d33@mail.gmail.com>
References: <m38xzllglg.fsf@theine.beaverton.ibm.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Return-path: <xen-devel-bounces@lists.xensource.com>
In-Reply-To: <m38xzllglg.fsf@theine.beaverton.ibm.com>
Content-Disposition: inline
List-Unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xensource.com>
List-Help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-Subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
Sender: xen-devel-bounces@lists.xensource.com
Errors-To: xen-devel-bounces@lists.xensource.com
To: Dan Smith <danms@us.ibm.com>
Cc: xen-devel@lists.xensource.com
List-Id: xen-devel@lists.xenproject.org

On 8/2/05, Dan Smith <danms@us.ibm.com> wrote:
> The attached patch converts the balloon driver and xend to use
> xenstore instead of control messages.
>=20
<snip>
> +static void watch_target(struct xenbus_watch *watch, const char *node)
> +{
> +    unsigned long new_target;
> +    int err;
> +
> +    if(watch =3D=3D &root_watch)
> +    {
> +        /* FIXME: This is part of a dom0 sequencing workaround */
> +        if(register_xenbus_watch(&xb_watch) =3D=3D 0)
> +        {
> +            /*
> +               We successfully set a watch on memory/target:
> +               now we can stop watching root
> +            */
> +            unregister_xenbus_watch(&root_watch);
> +            balloon_xenbus_init=3D1;
> +        }
> +        else
> +        {
> +            return;
> +        }
> +    }
> +
> +    err =3D xenbus_scanf("memory", "target", "%lu", &new_target);
> +
> +    if(err !=3D 1)
> +    {
> +        IPRINTK("Unable to read memory/target\n");
> +        return;
> +    }
> +
> +    set_new_target(new_target >> PAGE_SHIFT);

as under "memory"node, there probably are several nodes besides
"target" (that means what triggered this watch may be not balloon
request), i guess it is better to do some checking before calling
set_new_target, like this:


if (new_target !=3D target_pages)
    set_new_target(new_target >> PAGE_SHIFT);


regards,
aq