| Message ID | 1398780591-10644-2-git-send-email-vyasevic@redhat.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On 04/29/2014 10:09 PM, Vlad Yasevich wrote: > The following is a problematic configuration: > > VM1: virtio-net device connected to macvtap0@eth0 > VM2: e1000 device connect to macvtap1@eth0 > > The problem is is that virtio-net supports checksum offloading > and thus sends the packets to the host with CHECKSUM_PARTIAL set. > On the other hand, e1000 does not support any acceleration. > > For small TCP packets (and this includes the 3-way handshake), > e1000 ends up receiving packets that only have a partial checksum > set. This causes TCP to fail checksum validation and to drop > packets. As a result tcp connections can not be established. > > Commit 3e4f8b787370978733ca6cae452720a4f0c296b8 > macvtap: Perform GSO on forwarding path. > fixes this issue for large packets wthat will end up undergoing GSO. > This commit adds a check for the non-GSO case and attempts to > compute the checksum for partially checksummed packets in the > non-GSO case. > > CC: Daniel Lezcano <daniel.lezcano@free.fr> > CC: Patrick McHardy <kaber@trash.net> > CC: Andrian Nord <nightnord@gmail.com> > CC: Eric Dumazet <eric.dumazet@gmail.com> > CC: Michael S. Tsirkin <mst@redhat.com> > CC: Jason Wang <jasowang@redhat.com> > Signed-off-by: Vlad Yasevich <vyasevic@redhat.com> > --- > drivers/net/macvtap.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c > index ff111a8..3381c4f 100644 > --- a/drivers/net/macvtap.c > +++ b/drivers/net/macvtap.c > @@ -322,6 +322,15 @@ static rx_handler_result_t macvtap_handle_frame(struct sk_buff **pskb) > segs = nskb; > } > } else { > + /* If we receive a partial checksum and the tap side > + * doesn't support checksum offload, compute the checksum. > + * Note: it doesn't matter which checksum feature to > + * check, we either support them all or none. > + */ > + if (skb->ip_summed == CHECKSUM_PARTIAL && > + !(features & NETIF_F_ALL_CSUM) && > + skb_checksum_help(skb)) > + goto drop; > skb_queue_tail(&q->sk.sk_receive_queue, skb); > } > Acked-by: Jason Wang <jasowang@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index ff111a8..3381c4f 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -322,6 +322,15 @@ static rx_handler_result_t macvtap_handle_frame(struct sk_buff **pskb) segs = nskb; } } else { + /* If we receive a partial checksum and the tap side + * doesn't support checksum offload, compute the checksum. + * Note: it doesn't matter which checksum feature to + * check, we either support them all or none. + */ + if (skb->ip_summed == CHECKSUM_PARTIAL && + !(features & NETIF_F_ALL_CSUM) && + skb_checksum_help(skb)) + goto drop; skb_queue_tail(&q->sk.sk_receive_queue, skb); }
The following is a problematic configuration: VM1: virtio-net device connected to macvtap0@eth0 VM2: e1000 device connect to macvtap1@eth0 The problem is is that virtio-net supports checksum offloading and thus sends the packets to the host with CHECKSUM_PARTIAL set. On the other hand, e1000 does not support any acceleration. For small TCP packets (and this includes the 3-way handshake), e1000 ends up receiving packets that only have a partial checksum set. This causes TCP to fail checksum validation and to drop packets. As a result tcp connections can not be established. Commit 3e4f8b787370978733ca6cae452720a4f0c296b8 macvtap: Perform GSO on forwarding path. fixes this issue for large packets wthat will end up undergoing GSO. This commit adds a check for the non-GSO case and attempts to compute the checksum for partially checksummed packets in the non-GSO case. CC: Daniel Lezcano <daniel.lezcano@free.fr> CC: Patrick McHardy <kaber@trash.net> CC: Andrian Nord <nightnord@gmail.com> CC: Eric Dumazet <eric.dumazet@gmail.com> CC: Michael S. Tsirkin <mst@redhat.com> CC: Jason Wang <jasowang@redhat.com> Signed-off-by: Vlad Yasevich <vyasevic@redhat.com> --- drivers/net/macvtap.c | 9 +++++++++ 1 file changed, 9 insertions(+)