Re: [Xen-devel] [PATCH net-next V3 2/3] xen-netfront: split event channels support for Xen frontend driver

[annie li <annie.li@xxxxxxxxxx>]

On 2013-5-23 9:46, Wei Liu wrote:
> On Wed, May 22, 2013 at 09:38:20PM +0100, Wei Liu wrote:
> > On Wed, May 22, 2013 at 9:35 PM, annie li <annie.li@xxxxxxxxxx> wrote:
> > > On 2013-5-22 16:20, Wei Liu wrote:
> > > > On Wed, May 22, 2013 at 8:32 PM, annie li <annie.li@xxxxxxxxxx> wrote:
> > > > > Originally, netfront protects access to rx shared-ring with tx_lock, you
> > > > > remove this protection here. It is better to protect the ring access by a
> > > > > sperate rx_lock then.
> > > > TX ring and RX ring are separate rings. I don't think that comment / code
> > > > makes sense any more. My stress test confirms that.
> > > Yes, they are separate rings. Actually I am not sure why
> > > RING_HAS_UNCONSUMED_RESPONSES(&np->rx) is protected by any tx_lock
> > > originally. But for xennet_rx_interrupt, it is better to use rx_lock to
> > > protect RING_HAS_UNCONSUMED_RESPONSES(&np->rx).
> > This doesn't make sense to me either. Xen ring protocol is designed to
> > be lock-free.
> > And in netfront's case there is no concurrent access to the ring.
> Annie, did I answer your questions / relieve your concern?
Yes, I think you are correct.

Thanks
Annie

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