For the gso of sctp over udp packets, sctp_gso_segment() will be called in
skb_udp_tunnel_segment(), we need to set transport_header to sctp header.
As all the current HWs can't handle both crc checksum and udp checksum at
the same time, the crc checksum has to be done in sctp_gso_segment() by
removing the NETIF_F_SCTP_CRC flag from the features.
Meanwhile, if the HW can't do udp checksum, csum and csum_start has to be
set correctly, and udp checksum will be done in __skb_udp_tunnel_segment()
by calling gso_make_checksum().
Thanks to Paolo, Marcelo and Guillaume for helping with this one.
v1->v2:
- no change.
v2->v3:
- remove the he NETIF_F_SCTP_CRC flag from the features.
- set csum and csum_start in sctp_gso_make_checksum().
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
---
net/ipv4/udp_offload.c | 3 +++
net/sctp/offload.c | 6 +++++-
2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index e67a66f..4d31255 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -49,6 +49,7 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
__skb_pull(skb, tnl_hlen);
skb_reset_mac_header(skb);
skb_set_network_header(skb, skb_inner_network_offset(skb));
+ skb_set_transport_header(skb, skb_inner_transport_offset(skb));
skb->mac_len = skb_inner_network_offset(skb);
skb->protocol = new_protocol;
@@ -67,6 +68,8 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
(NETIF_F_HW_CSUM | NETIF_F_IP_CSUM))));
features &= skb->dev->hw_enc_features;
+ /* CRC checksum can't be handled by HW when it's a udp tunneling packet. */
+ features &= ~NETIF_F_SCTP_CRC;
/* The only checksum offload we care about from here on out is the
* outer one so strip the existing checksum feature flags and
diff --git a/net/sctp/offload.c b/net/sctp/offload.c
index 74847d6..9f6f818 100644
--- a/net/sctp/offload.c
+++ b/net/sctp/offload.c
@@ -27,7 +27,11 @@ static __le32 sctp_gso_make_checksum(struct sk_buff *skb)
{
skb->ip_summed = CHECKSUM_NONE;
skb->csum_not_inet = 0;
- gso_reset_checksum(skb, ~0);
+ /* csum and csum_start in gso cb may be needed to do the udp
+ * checksum when it's a udp tunneling packet.
+ */
+ SKB_GSO_CB(skb)->csum = (__force __wsum)~0;
+ SKB_GSO_CB(skb)->csum_start = skb_headroom(skb) + skb->len;
return sctp_compute_cksum(skb, skb_transport_offset(skb));
}
--
2.1.0
