netdev - Re: [net PATCH v5 1/6] virtio_net: use dev_kfree

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Date:   Tue, 24 Jan 2017 22:54:40 +0200
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     David Miller <davem@...emloft.net>
Cc:     john.fastabend@...il.com, jasowang@...hat.com,
        john.r.fastabend@...el.com, netdev@...r.kernel.org,
        alexei.starovoitov@...il.com, daniel@...earbox.net
Subject: Re: [net PATCH v5 1/6] virtio_net: use dev_kfree_skb for small
 buffer XDP receive

On Tue, Jan 24, 2017 at 03:11:39PM -0500, David Miller wrote:
> From: "Michael S. Tsirkin" <mst@...hat.com>
> Date: Tue, 24 Jan 2017 22:08:33 +0200
> 
> > On Tue, Jan 24, 2017 at 02:43:28PM -0500, David Miller wrote:
> >> From: "Michael S. Tsirkin" <mst@...hat.com>
> >> Date: Mon, 23 Jan 2017 23:08:35 +0200
> >> 
> >> > On Tue, Jan 17, 2017 at 02:19:50PM -0800, John Fastabend wrote:
> >> >> In the small buffer case during driver unload we currently use
> >> >> put_page instead of dev_kfree_skb. Resolve this by adding a check
> >> >> for virtnet mode when checking XDP queue type. Also name the
> >> >> function so that the code reads correctly to match the additional
> >> >> check.
> >> >> 
> >> >> Fixes: bb91accf2733 ("virtio-net: XDP support for small buffers")
> >> >> Signed-off-by: John Fastabend <john.r.fastabend@...el.com>
> >> >> Acked-by: Jason Wang <jasowang@...hat.com>
> >> > 
> >> > Acked-by: Michael S. Tsirkin <mst@...hat.com>
> >> > 
> >> > I think we definitely want this one in -net as it's
> >> > a bugfix.
> >> 
> >> This whole series is a bug fix, we must have adjust_header XDP
> >> support in the virtio_net driver before v4.10 goes out, it is
> >> a requires base feature for XDP.
> > 
> > I have to say device resets outside probe have a huge potential
> > to uncover hypervisor bugs. I am rather uncomfortable
> > doing that after -rc1.
> > 
> > How about a module option to disable it by default?
> > We can then ship a partial implementation in 4.10
> > and work on completing it in 4.11.
> 
> XDP programmers must be able to assume a base set of features being
> present, adjust_header is one of them.

Let's make all of XDP depend on this extra_headroom option then?

-- 
MST