netdev - [RFC PATCHv5 2/5] [TCP]: Extracted rexmit hint clearing from the LOST marking code

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Date:	Fri, 16 Mar 2007 20:41:03 +0200
From:	"Ilpo JÃ¤rvinen" <ilpo.jarvinen@...sinki.fi>
To:	netdev@...r.kernel.org
Cc:	David Miller <davem@...emloft.net>,
	"Ilpo JÃ¤rvinen" <ilpo.jarvinen@...sinki.fi>
Subject: [RFC PATCHv5 2/5] [TCP]: Extracted rexmit hint clearing from the LOST marking code

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...sinki.fi>
---
 net/ipv4/tcp_input.c |   31 ++++++++++++++++---------------
 1 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index dbc98ce..870404b 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1733,6 +1733,20 @@ static inline void tcp_reset_reno_sack(s
 	tp->left_out = tp->lost_out;
 }
 
+/* RFC: This is from the original, I doubt that this is necessary at all:
+ * clear xmit_retrans hint if seq of this skb is beyond hint. How could we
+ * retransmitted past LOST markings in the first place? I'm not fully sure
+ * about undo and end of connection cases, which can cause R without L?
+ */
+static void tcp_verify_retransmit_hint(struct tcp_sock *tp,
+				       struct sk_buff *skb)
+{
+	if ((tp->retransmit_skb_hint != NULL) &&
+	    before(TCP_SKB_CB(skb)->seq,
+	    TCP_SKB_CB(tp->retransmit_skb_hint)->seq))
+		tp->retransmit_skb_hint = skb;
+}
+
 /* Mark head of queue up as lost. */
 static void tcp_mark_head_lost(struct sock *sk, struct tcp_sock *tp,
 			       int packets, u32 high_seq)
@@ -1762,14 +1776,7 @@ static void tcp_mark_head_lost(struct so
 		if (!(TCP_SKB_CB(skb)->sacked&TCPCB_TAGBITS)) {
 			TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
 			tp->lost_out += tcp_skb_pcount(skb);
-
-			/* clear xmit_retransmit_queue hints
-			 *  if this is beyond hint */
-			if (tp->retransmit_skb_hint != NULL &&
-			    before(TCP_SKB_CB(skb)->seq,
-				   TCP_SKB_CB(tp->retransmit_skb_hint)->seq))
-				tp->retransmit_skb_hint = NULL;
-
+			tcp_verify_retransmit_hint(tp, skb);
 		}
 	}
 	tcp_sync_left_out(tp);
@@ -1808,13 +1815,7 @@ static void tcp_update_scoreboard(struct
 			if (!(TCP_SKB_CB(skb)->sacked&TCPCB_TAGBITS)) {
 				TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
 				tp->lost_out += tcp_skb_pcount(skb);
-
-				/* clear xmit_retrans hint */
-				if (tp->retransmit_skb_hint &&
-				    before(TCP_SKB_CB(skb)->seq,
-					   TCP_SKB_CB(tp->retransmit_skb_hint)->seq))
-
-					tp->retransmit_skb_hint = NULL;
+				tcp_verify_retransmit_hint(tp, skb);
 			}
 		}
 
-- 
1.4.2

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