netdev - Re: [Xen-devel] xen-netback notify DomU to send ARP.

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Message-ID: <50ED6255.7020006@oracle.com>
Date:	Wed, 09 Jan 2013 20:28:05 +0800
From:	jianhai luan <jianhai.luan@...cle.com>
To:	Jan Beulich <JBeulich@...e.com>
CC:	xen-devel@...ts.xensource.com, netdev@...r.kernel.org,
	Jan Beulich <JBeulich@...e.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: Re: [Xen-devel] xen-netback notify DomU to send ARP.


On 2013-1-9 18:06, Jan Beulich wrote:
>>>> On 09.01.13 at 08:39, jianhai luan <jianhai.luan@...cle.com> wrote:
>> @@ -34,11 +35,42 @@ static void connect(struct backend_info *);
>> static void backend_create_xenvif(struct backend_info *be);
>> static void unregister_hotplug_status_watch(struct backend_info *be);
>>
>> +#define nb_to_backend(nb) container_of(nb, struct backend_info, vif_notifier)
>> +/**
>> + * When network condition of vif change, notify the frontend.
>> + */
>> +static int netback_netdev_event(struct notifier_block *this,
>> +				unsigned long event, void *ptr)
>> +{
>> +	struct net_device *event_dev = (struct net_device *)ptr;
> Pointless cast.
>
>> +	struct backend_info *be = nb_to_backend(this);
>> +
>> +	pr_debug("event_dev: %s, event: %lx\n",
>> +		 event_dev ? event_dev->name : "None", event);
>> +
>> +	if (!be->vif)
>> +		goto out;
>> +
>> +	switch (event) {
>> +	case NETDEV_NOTIFY_PEERS:
>> +		/* Notify frontend to Send gratuitous ARP */
>> +		xenbus_switch_state(be->dev, XenbusStateInitialised);
>> +		xenbus_switch_state(be->dev, );
> This is the sort of change that clearly isn't acceptable, as I don't
> think you have ways to check _all_ existing frontends for their
> compatibility with this. A connected -> connected transition
> might be acceptable (that was done in the block frontend too, for
> implementing dynamic resize), but will likely need to be
> accompanied by a frontend side patch to handle that (which so
> far should be a no-op).
The latest xen net-frontent driver have handled the condition. State 
XenbusStateInitialised will do nothing,
but change to XenbusStateConnected will trigger 
netdev_notify_peers(netdev) to send ARP.
>
>> +		break;
>> +	default:
>> +		break;
> Pointless default case.
>
>> +	}
>> +
>> +out:
> I don't think you really need the label (and the goto above) - just
> put a return there.
>
>> +	return NOTIFY_DONE;
>> +}
>> +
>> static int netback_remove(struct xenbus_device *dev)
>> {
>> 	struct backend_info *be = dev_get_drvdata(&dev->dev);
>>
>> 	unregister_hotplug_status_watch(be);
>> +	unregister_netdevice_notifier(&be->vif_notifier);
>> 	if (be->vif) {
>> 		kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
>> 		xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
>> @@ -129,6 +161,10 @@ static int netback_probe(struct xenbus_device *dev,
>> 	/* This kicks hotplug scripts, so do it immediately. */
>> 	backend_create_xenvif(be);
>>
>> +	/*   Event Notify */
>> +	(be->vif_notifier).notifier_call = netback_netdev_event;
> Pointless parentheses.
>
> Jan
>
>> +	register_netdevice_notifier(&be->vif_notifier);
>> +
>> 	return 0;
>>
>> abort_transaction:
>


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