Re: [PATCH v3] tcp: fix tp->undo_retrans accounting in tcp_sacktag_one()
flat view
From: Eric Dumazet <hidden>
Date: 2021-09-13 15:52:21
On Mon, Sep 13, 2021 at 3:51 AM zhenggy [off-list ref] wrote:
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")nit: We normally do not add an empty line between Fixes: tag and others. Reviewed-by: Eric Dumazet <redacted>
quoted hunk ↗ jump to hunk
Signed-off-by: zhenggy <redacted> --- net/ipv4/tcp_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 3f7bd7a..141e85e 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c@@ -1346,7 +1346,7 @@ static u8 tcp_sacktag_one(struct sock *sk, 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) && before(start_seq, state->reord)) state->reord = start_seq; --1.8.3.1