[dpdk-dev] [PATCH] virtio: fix virtio_net_hdr desc pointing to the same buffer

Xie, Huawei huawei.xie at intel.com
Mon Dec 14 14:38:39 CET 2015



> -----Original Message-----
> From: Yuanhan Liu [mailto:yuanhan.liu at linux.intel.com]
> Sent: Monday, December 14, 2015 9:10 PM
> To: Thomas Monjalon
> Cc: Xie, Huawei; dev at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] virtio: fix virtio_net_hdr desc pointing to
> the same buffer
> 
> On Mon, Dec 14, 2015 at 01:44:54PM +0100, Thomas Monjalon wrote:
> > 2015-12-14 19:47, Yuanhan Liu:
> > > On Mon, Dec 14, 2015 at 10:32:24AM +0100, Thomas Monjalon wrote:
> > > > 2015-12-14 11:01, Yuanhan Liu:
> > > > > On Fri, Dec 11, 2015 at 12:07:32AM +0800, Huawei at dpdk.org wrote:
> > > > > > The virtio_net_hdr desc all pointed to the same buffer. It
> doesn't cause
> > > > > > issue because in the simple TX mode we don't use the header. This
> patch
> > > > > > makes the header desc point to different buffer.
> > > > > >
> > > > > > Signed-off-by: Huawei Xie <huawei.xie at intel.com>
> > > > >
> > > > > Acked-by: Yuanhan Liu <yuanhan.liu at linux.intel.com>
> > > >
> > > > Does it fix something in the current behaviour?
> > >
> > > It's more like a logic fixing to me.
> > >
> > > > I have the feeling it may wait for 2.3.
> > >
> > > It's been introduced in v2.2, with Huawei's simple tx patchset.
> > > Therefore, I guess 2.2 is good to go?
> >
> > The vhost driver has been validated without with patch.
> 
> Huawei stated in the commit log that "It doesn't cause issue because in
> the simple TX mode we don't use the header".
> 
> > Merging it would be taking the risk of breaking something
> > (or just reduce performance) for no clear benefit.
> > Am I missing something?
> 
Thomas, there is no risk at all with this patch, and it will not affect performance.
I prefer to integrate this patch, so that we have a good looking vhost library. :).
> I know your concerns: we really should be cagy about making any changes
> when a release is close, especially when all stuff are validated. From
> this point of view, I agree with you we could delay it to v2.3.
> 
> Maybe huawei have more inputs here?
> 
> 	--yliu


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