[ 34/72] tcp: fix tcp_shifted_skb() adjustment of lost_cnt_hint for FACK

From: Greg KH
Date: Mon Feb 27 2012 - 20:19:35 EST


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

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


From: Neal Cardwell <ncardwell@xxxxxxxxxx>

[ 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@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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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