linux-kernel - [ 34/72] tcp: fix tcp_shifted_skb() adjustment of lost_cnt

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Message-Id: <20120228010432.406804561@linuxfoundation.org>
Date:	Mon, 27 Feb 2012 17:05:03 -0800
From:	Greg KH <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Neal Cardwell <ncardwell@...gle.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [ 34/72] tcp: fix tcp_shifted_skb() adjustment of lost_cnt_hint for FACK

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Neal Cardwell <ncardwell@...gle.com>

[ Upstream commit 0af2a0d0576205dda778d25c6c344fc6508fc81d ]

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>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv4/tcp_input.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1406,6 +1406,10 @@ static int tcp_shifted_skb(struct sock *
 
 	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;
 


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