netdev - [PATCH] tcp: fix tcp_shifted_skb() adjustment of lost_cnt

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Message-Id: <1329200528-19718-1-git-send-email-ncardwell@google.com>
Date:	Tue, 14 Feb 2012 01:22:08 -0500
From:	Neal Cardwell <ncardwell@...gle.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, ilpo.jarvinen@...sinki.fi,
	Nandita Dukkipati <nanditad@...gle.com>,
	Yuchung Cheng <ycheng@...gle.com>,
	Tom Herbert <therbert@...gle.com>,
	Vijay Subramanian <subramanian.vijay@...il.com>,
	Neal Cardwell <ncardwell@...gle.com>
Subject: [PATCH] tcp: fix tcp_shifted_skb() adjustment of lost_cnt_hint for FACK

This commit ensures that lost_cnt_hint is correctly updated in
tcp_shifted_skb() for FACK TCP senders. The lost_cnt_hint adjustment
in tcp_sacktag_one() only applies to non-FACK senders, so FACK senders
need their own adjustment.

This applies the spirit of 1e5289e121372a3494402b1b131b41bfe1cf9b7f -
except now that the sequence range passed into tcp_sacktag_one() is
correct we need only have a special case adjustment for FACK.

Signed-off-by: Neal Cardwell <ncardwell@...gle.com>
---
 net/ipv4/tcp_input.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 8116d06..53c8ce4 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1403,6 +1403,10 @@ static int tcp_shifted_skb(struct sock *sk, struct sk_buff *skb,
 
 	BUG_ON(!pcount);
 
+	/* Adjust hint for FACK. Non-FACK is handled in tcp_sacktag_one(). */
+	if (tcp_is_fack(tp) && (skb == tp->lost_skb_hint))
+		tp->lost_cnt_hint += pcount;
+
 	TCP_SKB_CB(prev)->end_seq += shifted;
 	TCP_SKB_CB(skb)->seq += shifted;
 
-- 
1.7.7.3

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