From 94d3b1e586f6d4c7150501bde284c544ce99073c Mon Sep 17 00:00:00 2001 From: Ryousei Takano Date: Fri, 26 Oct 2007 04:27:59 -0700 Subject: [PATCH] [TCP]: fix D-SACK cwnd handling MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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: Ryousei Takano Signed-off-by: Ilpo Järvinen Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 457697a043d..69d8c38ccd3 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -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; -- 2.41.1