netdev - Re: [Xen-devel] [PATCH net-next 1/2] xen-netback: split event channels feature support

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Message-ID: <20130521143357.GO32007@zion.uk.xensource.com>
Date:	Tue, 21 May 2013 15:33:57 +0100
From:	Wei Liu <wei.liu2@...rix.com>
To:	David Vrabel <david.vrabel@...rix.com>
CC:	Wei Liu <wei.liu2@...rix.com>, <xen-devel@...ts.xen.org>,
	<netdev@...r.kernel.org>, <ian.campbell@...rix.com>,
	<konrad.wilk@...cle.com>
Subject: Re: [Xen-devel] [PATCH net-next 1/2] xen-netback: split event
 channels feature support

On Tue, May 21, 2013 at 02:34:19PM +0100, David Vrabel wrote:
> > +
> > +static irqreturn_t xenvif_rx_interrupt(int irq, void *dev_id)
> > +{
> > +	struct xenvif *vif = dev_id;
> > +
> > +	if (vif->netbk == NULL)
> > +		return IRQ_NONE;
> 
> I know the original code had this but this looks suspect to me.  Event
> channels are never shared so it does not make sense to ever return IRQ_NONE.
> 
> Suggest making this return IRQ_HANDLED instead (and similarly in
> xenvif_tx_interrupt()) and...
> 

Fixed.

> > +static irqreturn_t xenvif_interrupt(int irq, void *dev_id)
> > +{
> > +	struct xenvif *vif = dev_id;
> > +
> > +	if (vif->netbk == NULL)
> > +		return IRQ_NONE;
> 
> ... then you can remove this test.

Fixed.

> 
> > --- a/drivers/net/xen-netback/xenbus.c
> > +++ b/drivers/net/xen-netback/xenbus.c
> > @@ -114,6 +114,15 @@ static int netback_probe(struct xenbus_device *dev,
> >  			goto abort_transaction;
> >  		}
> >  
> > +		/* Split event channels support */
> > +		err = xenbus_printf(xbt, dev->nodename,
> > +				"feature-split-event-channels",
> > +				"%u", 1);
> > +		if (err) {
> > +			message = "writing feature-split-event-channels";
> > +			goto abort_transaction;
> > +		}
> > +
> 
> Event channels are currently a limited resource.  Do we want to have a
> knob to disable this feature?

Knob feature_split_event_channels added.


Wei.
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