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authorYuchung Cheng <ycheng@google.com>2011-02-07 12:57:04 +0000
committerDavid S. Miller <davem@davemloft.net>2011-02-21 11:31:18 -0800
commitc24f691b56107feeba076616982093ee2d3c8fb5 (patch)
tree90317e187a511635fdb8682384fc8eb99f1de21f /net/ipv4/tcp_input.c
parent5f04d5068a90602b93a7953e9a47c496705c6976 (diff)
tcp: undo_retrans counter fixes
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 <ycheng@google.com> Acked-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_input.c')
-rw-r--r--net/ipv4/tcp_input.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index eb7f82ebf4a3..65f6c0406245 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);