From b7b0ed910cd8450db6d98cd4361c644bb1c88412 Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Mon, 18 May 2015 12:31:45 -0700 Subject: [PATCH] tcp: don't over-send F-RTO probes After sending the new data packets to probe (step 2), F-RTO may incorrectly send more probes if the next ACK advances SND_UNA and does not sack new packet. However F-RTO RFC 5682 probes at most once. This bug may cause sender to always send new data instead of repairing holes, inducing longer HoL blocking on the receiver for the application. Signed-off-by: Yuchung Cheng Signed-off-by: Neal Cardwell Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 9faf775a8c4a..243d674b3ef5 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2710,9 +2710,9 @@ static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack) tcp_try_undo_loss(sk, true)) return; - if (after(tp->snd_nxt, tp->high_seq) && - (flag & FLAG_DATA_SACKED || is_dupack)) { - tp->frto = 0; /* Loss was real: 2nd part of step 3.a */ + if (after(tp->snd_nxt, tp->high_seq)) { + if (flag & FLAG_DATA_SACKED || is_dupack) + tp->frto = 0; /* Step 3.a. loss was real */ } else if (flag & FLAG_SND_UNA_ADVANCED && !recovered) { tp->high_seq = tp->snd_nxt; __tcp_push_pending_frames(sk, tcp_current_mss(sk), -- 2.20.1