[PATCH v4 net-next v4 4/6] net: create tcp_gro_lookup helper function

Felix Fietkau
2024-04-27T18:23:15Z

This pulls the flow port matching out of tcp_gro_receive, so that it can be
reused for the next change, which adds the TCP fraglist GRO heuristic.

Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
include/net/tcp.h | 1 +
net/ipv4/tcp_offload.c | 41 +++++++++++++++++++++++++----------------
2 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index a9eb21251195..9f08ecab26e0 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2199,6 +2199,7 @@ void tcp_v4_destroy_sock(struct sock *sk);

struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
netdev_features_t features);
+struct sk_buff *tcp_gro_lookup(struct list_head *head, struct tcphdr *th);
struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb);
INDIRECT_CALLABLE_DECLARE(int tcp4_gro_complete(struct sk_buff *skb, int thoff));
INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb));
diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index aa7508676315..4a194a9d36cd 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -245,6 +245,27 @@ struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
return segs;
}

+struct sk_buff *tcp_gro_lookup(struct list_head *head, struct tcphdr *th)
+{
+ struct tcphdr *th2;
+ struct sk_buff *p;
+
+ list_for_each_entry(p, head, list) {
+ if (!NAPI_GRO_CB(p)->same_flow)
+ continue;
+
+ th2 = tcp_hdr(p);
+ if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
+ NAPI_GRO_CB(p)->same_flow = 0;
+ continue;
+ }
+
+ return p;
+ }
+
+ return NULL;
+}
+
struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb)
{
struct sk_buff *pp = NULL;
@@ -282,24 +303,12 @@ struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb)
len = skb_gro_len(skb);
flags = tcp_flag_word(th);

- list_for_each_entry(p, head, list) {
- if (!NAPI_GRO_CB(p)->same_flow)
- continue;
-
- th2 = tcp_hdr(p);
-
- if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
- NAPI_GRO_CB(p)->same_flow = 0;
- continue;
- }
-
- goto found;
- }
- p = NULL;
- goto out_check_final;
+ p = tcp_gro_lookup(head, th);
+ if (!p)
+ goto out_check_final;

-found:
/* Include the IP ID check below from the inner most IP hdr */
+ th2 = tcp_hdr(p);
flush = NAPI_GRO_CB(p)->flush;
flush |= (__force int)(flags & TCP_FLAG_CWR);
flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
--
2.44.0