netdev - [PATCH v4 net-next v4 4/6] net: create tcp_gro

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Message-ID: <20240427182305.24461-5-nbd@nbd.name>
Date: Sat, 27 Apr 2024 20:23:00 +0200
From: Felix Fietkau <nbd@....name>
To: netdev@...r.kernel.org,
	Eric Dumazet <edumazet@...gle.com>,
	"David S. Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	David Ahern <dsahern@...nel.org>
Cc: willemdebruijn.kernel@...il.com,
	linux-kernel@...r.kernel.org
Subject: [PATCH v4 net-next v4 4/6] net: create tcp_gro_lookup helper function

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@...gle.com>
Signed-off-by: Felix Fietkau <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