netdev - [PATCH net-next] tcp: small optimization when TCP_TW

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Message-ID: <20240411082530.907113-1-edumazet@google.com>
Date: Thu, 11 Apr 2024 08:25:29 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>, Neal Cardwell <ncardwell@...gle.com>
Subject: [PATCH net-next] tcp: small optimization when TCP_TW_SYN is processed

When TCP_TW_SYN is processed, we perform a lookup to find
a listener and jump back in tcp_v6_rcv() and tcp_v4_rcv()

Paolo suggested that we do not have to check if the
found socket is a TIME_WAIT or NEW_SYN_RECV one.

Suggested-by: Paolo Abeni <pabeni@...hat.com>
Link: https://lore.kernel.org/netdev/68085c8a84538cacaac991415e4ccc72f45e76c2.camel@redhat.com/
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Neal Cardwell <ncardwell@...gle.com>
---
 net/ipv4/tcp_ipv4.c | 2 +-
 net/ipv6/tcp_ipv6.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 1e650ec71d2fe5198b9dad9e6ea9c5eaf868277f..88c83ac4212957f19efad0f967952d2502bdbc7f 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2205,7 +2205,6 @@ int tcp_v4_rcv(struct sk_buff *skb)
 	if (!sk)
 		goto no_tcp_socket;
 
-process:
 	if (sk->sk_state == TCP_TIME_WAIT)
 		goto do_time_wait;
 
@@ -2285,6 +2284,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
 		}
 	}
 
+process:
 	if (static_branch_unlikely(&ip4_min_ttl)) {
 		/* min_ttl can be changed concurrently from do_ip_setsockopt() */
 		if (unlikely(iph->ttl < READ_ONCE(inet_sk(sk)->min_ttl))) {
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 3aa9da5c9a669d2754b421cfb704ad28def5a748..bb7c3caf4f8536dabdcb3dbe7c90aff9c8985c90 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1794,7 +1794,6 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
 	if (!sk)
 		goto no_tcp_socket;
 
-process:
 	if (sk->sk_state == TCP_TIME_WAIT)
 		goto do_time_wait;
 
@@ -1871,6 +1870,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
 		}
 	}
 
+process:
 	if (static_branch_unlikely(&ip6_min_hopcount)) {
 		/* min_hopcount can be changed concurrently from do_ipv6_setsockopt() */
 		if (unlikely(hdr->hop_limit < READ_ONCE(tcp_inet6_sk(sk)->min_hopcount))) {
-- 
2.44.0.478.gd926399ef9-goog