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

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2015-12-14 13:38, Xie, Huawei:
> From: Yuanhan Liu [mailto:yuanhan.liu@linux.intel.com]
> > 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@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@intel.com>
> > > > > >
> > > > > > Acked-by: Yuanhan Liu <yuanhan.liu@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'm not sure that "good looking" is enough.
I'll wait for another opinion before merging, so we'll have 2 responsibles
in case of failure :)

> > 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