[PATCH v4 net-next v4 3/6] net: add code for TCP fraglist GRO

Felix Fietkau
2024-04-27T18:23:16Z

This implements fraglist GRO similar to how it's handled in UDP, however
no functional changes are added yet. The next change adds a heuristic for
using fraglist GRO instead of regular GRO.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
net/ipv4/tcp_offload.c | 21 +++++++++++++++++++++
net/ipv6/tcpv6_offload.c | 9 +++++++++
2 files changed, 30 insertions(+)

diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index affd4ed28cfe..aa7508676315 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -334,6 +334,18 @@ struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb)
flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
flush |= skb_cmp_decrypted(p, skb);

+ if (unlikely(NAPI_GRO_CB(p)->is_flist)) {
+ flush |= (__force int)(flags ^ tcp_flag_word(th2));
+ flush |= skb->ip_summed != p->ip_summed;
+ flush |= skb->csum_level != p->csum_level;
+ flush |= NAPI_GRO_CB(p)->count >= 64;
+
+ if (flush || skb_gro_receive_list(p, skb))
+ mss = 1;
+
+ goto out_check_final;
+ }
+
if (flush || skb_gro_receive(p, skb)) {
mss = 1;
goto out_check_final;
@@ -400,6 +412,15 @@ INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff)
const struct iphdr *iph = ip_hdr(skb);
struct tcphdr *th = tcp_hdr(skb);

+ if (unlikely(NAPI_GRO_CB(skb)->is_flist)) {
+ skb_shinfo(skb)->gso_type |= SKB_GSO_FRAGLIST | SKB_GSO_TCPV4;
+ skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
+
+ __skb_incr_checksum_unnecessary(skb);
+
+ return 0;
+ }
+
th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
iph->daddr, 0);

diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c
index 7180c30dbbef..575e2743e331 100644
--- a/net/ipv6/tcpv6_offload.c
+++ b/net/ipv6/tcpv6_offload.c
@@ -32,6 +32,15 @@ INDIRECT_CALLABLE_SCOPE int tcp6_gro_complete(struct sk_buff *skb, int thoff)
const struct ipv6hdr *iph = ipv6_hdr(skb);
struct tcphdr *th = tcp_hdr(skb);

+ if (unlikely(NAPI_GRO_CB(skb)->is_flist)) {
+ skb_shinfo(skb)->gso_type |= SKB_GSO_FRAGLIST | SKB_GSO_TCPV6;
+ skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
+
+ __skb_incr_checksum_unnecessary(skb);
+
+ return 0;
+ }
+
th->check = ~tcp_v6_check(skb->len - thoff, &iph->saddr,
&iph->daddr, 0);
skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV6;
--
2.44.0