netdev - [PATCH net-next 04/10] tcp: make tcp_rcv_state

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Message-Id: <20220416001048.2218911-5-eric.dumazet@gmail.com>
Date:   Fri, 15 Apr 2022 17:10:42 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH net-next 04/10] tcp: make tcp_rcv_state_process() drop monitor friendly

From: Eric Dumazet <edumazet@...gle.com>

tcp_rcv_state_process() incorrectly drops packets
instead of consuming it, making drop monitor very noisy,
if not unusable.

Calling tcp_time_wait() or tcp_done() is part
of standard behavior, packets triggering these actions
were not dropped.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/tcp_input.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 9a1cb3f48c3fb26beac4283001d38828ca15a4d9..f95a8368981d319400d0f46b81ced954d941f718 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6580,7 +6580,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 			inet_csk_reset_keepalive_timer(sk, tmo);
 		} else {
 			tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
-			goto discard;
+			goto consume;
 		}
 		break;
 	}
@@ -6588,7 +6588,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 	case TCP_CLOSING:
 		if (tp->snd_una == tp->write_seq) {
 			tcp_time_wait(sk, TCP_TIME_WAIT, 0);
-			goto discard;
+			goto consume;
 		}
 		break;
 
@@ -6596,7 +6596,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 		if (tp->snd_una == tp->write_seq) {
 			tcp_update_metrics(sk);
 			tcp_done(sk);
-			goto discard;
+			goto consume;
 		}
 		break;
 	}
@@ -6650,6 +6650,10 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 		tcp_drop(sk, skb);
 	}
 	return 0;
+
+consume:
+	__kfree_skb(skb);
+	return 0;
 }
 EXPORT_SYMBOL(tcp_rcv_state_process);
 
-- 
2.36.0.rc0.470.gd361397f0d-goog