netdev - [PATCH net-next 1/4] tcp: consistently check retransmit hint

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Message-Id: <20200925170431.1099943-2-ycheng@google.com>
Date:   Fri, 25 Sep 2020 10:04:28 -0700
From:   Yuchung Cheng <ycheng@...gle.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, edumazet@...gle.com, ncardwell@...gle.com,
        Yuchung Cheng <ycheng@...gle.com>
Subject: [PATCH net-next 1/4] tcp: consistently check retransmit hint

tcp_simple_retransmit() used for path MTU discovery may not adjust
the retransmit hint properly by deducting retrans_out before checking
it to adjust the hint. This patch fixes this by a correct routine
tcp_mark_skb_lost() already used by the RACK loss detection.

Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
Signed-off-by: Neal Cardwell <ncardwell@...gle.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/tcp_input.c    | 9 ++-------
 net/ipv4/tcp_recovery.c | 2 +-
 2 files changed, 3 insertions(+), 8 deletions(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 50834e7f958e..f84420dc7d37 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2675,13 +2675,8 @@ void tcp_simple_retransmit(struct sock *sk)
 
 	skb_rbtree_walk(skb, &sk->tcp_rtx_queue) {
 		if (tcp_skb_seglen(skb) > mss &&
-		    !(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) {
-			if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) {
-				TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
-				tp->retrans_out -= tcp_skb_pcount(skb);
-			}
-			tcp_skb_mark_lost_uncond_verify(tp, skb);
-		}
+		    !(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))
+			tcp_mark_skb_lost(sk, skb);
 	}
 
 	tcp_clear_retrans_hints_partial(tp);
diff --git a/net/ipv4/tcp_recovery.c b/net/ipv4/tcp_recovery.c
index fdb715bdd2d1..26a42289a870 100644
--- a/net/ipv4/tcp_recovery.c
+++ b/net/ipv4/tcp_recovery.c
@@ -246,6 +246,6 @@ void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced)
 			tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb,
 				     mss, mss, GFP_ATOMIC);
 
-		tcp_skb_mark_lost_uncond_verify(tp, skb);
+		tcp_mark_skb_lost(sk, skb);
 	}
 }
-- 
2.28.0.681.g6f77f65b4e-goog