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Commit 94d3b1e5 authored by Ryousei Takano's avatar Ryousei Takano Committed by David S. Miller
Browse files

[TCP]: fix D-SACK cwnd handling 

In the current net-2.6 kernel, handling FLAG_DSACKING_ACK is broken.
The flag is cleared to 1 just after FLAG_DSACKING_ACK is set.

        if (found_dup_sack)
                flag |= FLAG_DSACKING_ACK;
	:
	flag = 1;

To fix it, this patch introduces a part of the tcp_sacktag_state patch:
	http://marc.info/?l=linux-netdev&m=119210560431519&w=2



Signed-off-by: default avatarRyousei Takano <takano-ryousei@aist.go.jp>
Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 43cc7380

net/ipv4/tcp_input.c

+5 −7
Original line number Diff line number Diff line
@@ -1248,6 +1248,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ 
	int cached_fack_count;

	int i;

	int first_sack_index;

	int force_one_sack;



	if (!tp->sacked_out) {

		if (WARN_ON(tp->fackets_out))
@@ -1272,18 +1273,18 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ 
	 * if the only SACK change is the increase of the end_seq of

	 * the first block then only apply that SACK block

	 * and use retrans queue hinting otherwise slowpath */

	flag = 1;

	force_one_sack = 1;

	for (i = 0; i < num_sacks; i++) {

		__be32 start_seq = sp[i].start_seq;

		__be32 end_seq = sp[i].end_seq;



		if (i == 0) {

			if (tp->recv_sack_cache[i].start_seq != start_seq)

				flag = 0;

				force_one_sack = 0;

		} else {

			if ((tp->recv_sack_cache[i].start_seq != start_seq) ||

			    (tp->recv_sack_cache[i].end_seq != end_seq))

				flag = 0;

				force_one_sack = 0;

		}

		tp->recv_sack_cache[i].start_seq = start_seq;

		tp->recv_sack_cache[i].end_seq = end_seq;
@@ -1295,7 +1296,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ 
	}



	first_sack_index = 0;

	if (flag)

	if (force_one_sack)

		num_sacks = 1;

	else {

		int j;
@@ -1321,9 +1322,6 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ 
		}

	}



	/* clear flag as used for different purpose in following code */

	flag = 0;



	/* Use SACK fastpath hint if valid */

	cached_skb = tp->fastpath_skb_hint;

	cached_fack_count = tp->fastpath_cnt_hint;