netdev - [PATCH 7/9] [TCP]: Correct fastpath entrypoint below high

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Date:	Sat, 26 May 2007 11:36:00 +0300
From:	"Ilpo Järvinen" <ilpo.jarvinen@...sinki.fi>
To:	netdev@...r.kernel.org
Cc:	David Miller <davem@...emloft.net>,
	"Ilpo Järvinen" <ilpo.jarvinen@...sinki.fi>
Subject: [PATCH 7/9] [TCP]: Correct fastpath entrypoint below high_seq

From: =?ISO-8859-1?q?Ilpo_J=E4rvinen?= <ilpo.jarvinen@...sinki.fi>

In addition, implemented find_below using minus one. Some
reorganization was necessary to make code efficient again.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...sinki.fi>
---
 net/ipv4/tcp_input.c |   31 +++++++++++++++++++++----------
 1 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index fbce87f..8c1e38a 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1913,22 +1913,33 @@ struct sk_buff *tcp_update_scoreboard_fack(struct sock *sk, u32 entry_seq,
 	struct sk_buff *skb;
 	unsigned int holes_seen = 0;
 
-	skb = tcp_write_queue_find(sk, entry_seq);
-	/* If this ever becomes expensive, it can be delayed */
-	timedout_continue = tcp_write_queue_next(sk, skb);
 	if (entry_seq != tp->highest_sack) {
-		/* Not interested in "the last" SACKed one we got */
-		/* RFC: find_below could help here too */
-		skb = tcp_write_queue_prev(sk, skb);
+		/* Look for skb below min_seq(entry_seq, tp->high_seq) */
+		if (!after(entry_seq, tp->high_seq)) {
+			skb = tcp_write_queue_find(sk, entry_seq - 1);
+		} else {
+			BUG_ON(tp->snd_una == tp->high_seq);
+			skb = tcp_write_queue_find(sk, tp->high_seq - 1);
+		}
+
+		timedout_continue = NULL;
 		if (IsFack(tp) && tcp_skb_timedout(sk, skb) &&
 		    (tp->fackets_out < tp->packets_out)) {
-			timedout_continue = tcp_write_queue_find(sk, tp->highest_sack);
-			timedout_continue = tcp_write_queue_next(sk, timedout_continue);
-		} else
-			timedout_continue = NULL;
+			timedout_continue = tcp_write_queue_next(sk, skb);
+		    	if (!after(entry_seq, tp->high_seq)) {
+				/* Use latest SACK info in skipping past skbs */
+				timedout_continue = tcp_write_queue_find(sk, tp->highest_sack);
+				timedout_continue = tcp_write_queue_next(sk, timedout_continue);
+			}
+		}
+
 	} else {
 		unsigned int reord_count = IsFack(tp) ? 0 : 1;
 
+		skb = tcp_write_queue_find(sk, entry_seq);
+		/* If this ever becomes expensive, it can be delayed */
+		timedout_continue = tcp_write_queue_next(sk, skb);
+
 		/* Phase I: Search until TCP can mark */
 		tcp_for_write_queue_backwards_from(skb, sk) {
 			if ((tp->fackets_out <= tp->sacked_out + tp->lost_out +
-- 
1.5.0.6

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