From: zhenggy zhenggy@chinatelecom.cn
commit 4f884f3962767877d7aabbc1ec124d2c307a4257 upstream.
Commit 10d3be569243 ("tcp-tso: do not split TSO packets at retransmit time") may directly retrans a multiple segments TSO/GSO packet without split, Since this commit, we can no longer assume that a retransmitted packet is a single segment.
This patch fixes the tp->undo_retrans accounting in tcp_sacktag_one() that use the actual segments(pcount) of the retransmitted packet.
Before that commit (10d3be569243), the assumption underlying the tp->undo_retrans-- seems correct.
Fixes: 10d3be569243 ("tcp-tso: do not split TSO packets at retransmit time") Signed-off-by: zhenggy zhenggy@chinatelecom.cn Reviewed-by: Eric Dumazet edumazet@google.com Acked-by: Yuchung Cheng ycheng@google.com Acked-by: Neal Cardwell ncardwell@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/tcp_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1220,7 +1220,7 @@ static u8 tcp_sacktag_one(struct sock *s if (dup_sack && (sacked & TCPCB_RETRANS)) { if (tp->undo_marker && tp->undo_retrans > 0 && after(end_seq, tp->undo_marker)) - tp->undo_retrans--; + tp->undo_retrans = max_t(int, 0, tp->undo_retrans - pcount); if (sacked & TCPCB_SACKED_ACKED) state->reord = min(fack_count, state->reord); }