virtio-net: restrict build_skb() use to some arches

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build_skb() is supposed to be followed by
skb_reserve(skb, NET_IP_ALIGN), so that IP headers are word-aligned.
(Best practice is to reserve NET_IP_ALIGN+NET_SKB_PAD, but the NET_SKB_PAD
part is only a performance optimization if tunnel encaps are added.)

Unfortunately virtio_net has not provisioned this reserve.
We can only use build_skb() for arches where NET_IP_ALIGN == 0

We might refine this later, with enough testing.

Fixes: fb32856b16 ("virtio-net: page_to_skb() use build_skb when there's sufficient tailroom")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: David S. Miller <davem@davemloft.net>

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Eric Dumazet 2021-04-20 13:01:44 -07:00 • committed by David S. Miller

parent b8c55ce266

commit f5d7872a8b

1 changed files with 1 additions and 1 deletions

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drivers/net/virtio_net.c

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