On Mon, Sep 23, 2019 at 09:01:13AM -0400, Willem de Bruijn wrote:

On Fri, Sep 20, 2019 at 12:49 AM Steffen Klassert
[off-list ref] wrote:

quoted

This patch extends UDP GRO to support fraglist GRO/GSO
by using the previously introduced infrastructure.
All UDP packets that are not targeted to a GRO capable
UDP sockets are going to fraglist GRO now (local input
and forward).

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

quoted

@@ -538,6 +579,15 @@ INDIRECT_CALLABLE_SCOPE int udp4_gro_complete(struct sk_buff *skb, int nhoff)
        const struct iphdr *iph = ip_hdr(skb);
        struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);

+       if (NAPI_GRO_CB(skb)->is_flist) {
+               uh->len = htons(skb->len - nhoff);
+
+               skb_shinfo(skb)->gso_type |= (SKB_GSO_FRAGLIST|SKB_GSO_UDP_L4);
+               skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
+
+               return 0;
+       }
+
        if (uh->check)
                uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
                                          iph->daddr, 0);

diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
index 435cfbadb6bd..8836f2b69ef3 100644
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c

@@ -150,6 +150,15 @@ INDIRECT_CALLABLE_SCOPE int udp6_gro_complete(struct sk_buff *skb, int nhoff)
        const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
        struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);

+       if (NAPI_GRO_CB(skb)->is_flist) {
+               uh->len = htons(skb->len - nhoff);
+
+               skb_shinfo(skb)->gso_type |= (SKB_GSO_FRAGLIST|SKB_GSO_UDP_L4);
+               skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
+
+               return 0;
+       }
+

This is the same logic as in udp4_gro_complete. Can it be deduplicated
in udp_gro_complete?

The code below would mess up the checksum then. We did not change
the packets, so the checksum is still correct.

quoted

        if (uh->check)
                uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
                                          &ipv6h->daddr, 0);