From 79861919b8896e14b8e5707242721f2312c57ae4 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 18 Oct 2018 09:12:19 -0700 Subject: [PATCH] tcp: fix TCP_REPAIR xmit queue setup Andrey reported the following warning triggered while running CRIU tests: tcp_clean_rtx_queue() ... last_ackt = tcp_skb_timestamp_us(skb); WARN_ON_ONCE(last_ackt == 0); This is caused by 5f6188a8003d ("tcp: do not change tcp_wstamp_ns in tcp_mstamp_refresh"), as we end up having skbs in retransmit queue with a zero skb->skb_mstamp_ns field. We could fix this bug in different ways, like making sure tp->tcp_wstamp_ns is not zero at socket creation, but as Neal pointed out, we also do not want that pacing status of a repaired socket could push tp->tcp_wstamp_ns far ahead in the future. So we prefer changing tcp_write_xmit() to not call tcp_update_skb_after_send() and instead do what is requested by TCP_REPAIR logic. Fixes: 5f6188a8003d ("tcp: do not change tcp_wstamp_ns in tcp_mstamp_refresh") Signed-off-by: Eric Dumazet Reported-by: Andrey Vagin Acked-by: Soheil Hassas Yeganeh Acked-by: Neal Cardwell Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index d212e4cbc689..c07990a35ff3 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2321,18 +2321,19 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, while ((skb = tcp_send_head(sk))) { unsigned int limit; + if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { + /* "skb_mstamp_ns" is used as a start point for the retransmit timer */ + skb->skb_mstamp_ns = tp->tcp_wstamp_ns = tp->tcp_clock_cache; + list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); + goto repair; /* Skip network transmission */ + } + if (tcp_pacing_check(sk)) break; tso_segs = tcp_init_tso_segs(skb, mss_now); BUG_ON(!tso_segs); - if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { - /* "skb_mstamp" is used as a start point for the retransmit timer */ - tcp_update_skb_after_send(sk, skb, tp->tcp_wstamp_ns); - goto repair; /* Skip network transmission */ - } - cwnd_quota = tcp_cwnd_test(tp, skb); if (!cwnd_quota) { if (push_one == 2)