From c24f691b56107feeba076616982093ee2d3c8fb5 Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Mon, 7 Feb 2011 12:57:04 +0000 Subject: tcp: undo_retrans counter fixes MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Fix a bug that undo_retrans is incorrectly decremented when undo_marker is not set or undo_retrans is already 0. This happens when sender receives more DSACK ACKs than packets retransmitted during the current undo phase. This may also happen when sender receives DSACK after the undo operation is completed or cancelled. Fix another bug that undo_retrans is incorrectly incremented when sender retransmits an skb and tcp_skb_pcount(skb) > 1 (TSO). This case is rare but not impossible. Signed-off-by: Yuchung Cheng Acked-by: Ilpo Järvinen Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'net/ipv4/tcp_input.c') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index eb7f82ebf4a..65f6c040624 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1222,7 +1222,7 @@ static int tcp_check_dsack(struct sock *sk, struct sk_buff *ack_skb, } /* D-SACK for already forgotten data... Do dumb counting. */ - if (dup_sack && + if (dup_sack && tp->undo_marker && tp->undo_retrans && !after(end_seq_0, prior_snd_una) && after(end_seq_0, tp->undo_marker)) tp->undo_retrans--; @@ -1299,7 +1299,8 @@ static u8 tcp_sacktag_one(struct sk_buff *skb, struct sock *sk, /* Account D-SACK for retransmitted packet. */ if (dup_sack && (sacked & TCPCB_RETRANS)) { - if (after(TCP_SKB_CB(skb)->end_seq, tp->undo_marker)) + if (tp->undo_marker && tp->undo_retrans && + after(TCP_SKB_CB(skb)->end_seq, tp->undo_marker)) tp->undo_retrans--; if (sacked & TCPCB_SACKED_ACKED) state->reord = min(fack_count, state->reord); -- cgit v1.2.3-70-g09d2