Messages in this thread | | | Subject | Re: [PATCH net] virtio-net: unbreak cusmed packet for small buffer XDP | From | Jason Wang <> | Date | Wed, 28 Jun 2017 10:45:18 +0800 |
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On 2017年06月28日 10:17, Michael S. Tsirkin wrote: > On Wed, Jun 28, 2017 at 10:14:34AM +0800, Jason Wang wrote: >> >> On 2017年06月28日 10:02, Michael S. Tsirkin wrote: >>> On Wed, Jun 28, 2017 at 09:54:03AM +0800, Jason Wang wrote: >>>> We should allow csumed packet for small buffer, otherwise XDP_PASS >>>> won't work correctly. >>>> >>>> Fixes commit bb91accf2733 ("virtio-net: XDP support for small buffers") >>>> Signed-off-by: Jason Wang <jasowang@redhat.com> >>> The issue would be VIRTIO_NET_HDR_F_DATA_VALID might be set. >>> What do you think? >> I think it's safe. For XDP_PASS, it work like in the past. > That's the part I don't get. With DATA_VALID csum in packet is wrong, XDP > tools assume it's value.
DATA_VALID is CHECKSUM_UNCESSARY on the host, and according to the comment in skbuff.h
" * The hardware you're dealing with doesn't calculate the full checksum * (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums * for specific protocols. For such packets it will set CHECKSUM_UNNECESSARY * if their checksums are okay. skb->csum is still undefined in this case * though. A driver or device must never modify the checksum field in the * packet even if checksum is verified. "
The csum is correct I believe?
Thanks
> >> For XDP_TX, we >> zero the vnet header. > Again TX offload is disabled, so packets will go out with an invalid > checksum. > >> For adjusting header, XDP prog should deal with csum. >> >> Thanks > That part seems right. > >>>> --- >>>> The patch is needed for -stable. >>>> --- >>>> drivers/net/virtio_net.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >>>> index 143d8a9..499fcc9 100644 >>>> --- a/drivers/net/virtio_net.c >>>> +++ b/drivers/net/virtio_net.c >>>> @@ -413,7 +413,7 @@ static struct sk_buff *receive_small(struct net_device *dev, >>>> void *orig_data; >>>> u32 act; >>>> - if (unlikely(hdr->hdr.gso_type || hdr->hdr.flags)) >>>> + if (unlikely(hdr->hdr.gso_type)) >>>> goto err_xdp; >>>> xdp.data_hard_start = buf + VIRTNET_RX_PAD + vi->hdr_len; >>>> -- >>>> 2.7.4
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