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Date:   Wed, 23 Mar 2022 21:04:57 +0800
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From:   Jianguo Wu <wujianguo106@163.com>
Subject: [PATCH net-next] tcp: make tcp_rcv_state_process() drop monitor
 friendly
To:     dsahern@kernel.org, Jakub Kicinski <kuba@kernel.org>,
        menglong8.dong@gmail.com
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        edumazet@google.com
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From: Jianguo Wu <wujianguo@chinatelecom.cn>

In tcp_rcv_state_process(), should not call tcp_drop() for same case,
like after process ACK packet in TCP_LAST_ACK state, it should call
consume_skb() instead of tcp_drop() to be drop monitor friendly,
otherwise every last ack will be report as dropped packet by drop monitor.

Signed-off-by: Jianguo Wu <wujianguo@chinatelecom.cn>
---
 net/ipv4/tcp_input.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 2088f93..feb6f83 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6574,7 +6574,8 @@ 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;
+			consume_skb(skb);
+			return 0;
 		}
 		break;
 	}
@@ -6582,7 +6583,8 @@ 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;
+			consume_skb(skb);
+			return 0;
 		}
 		break;

@@ -6590,7 +6592,8 @@ 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;
+			consume_skb(skb);
+			return 0;
 		}
 		break;
 	}
-- 
1.8.3.1