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 <eduma...@google.com>
Reported-by: Andrey Vagin <ava...@openvz.org>
Acked-by: Soheil Hassas Yeganeh <soh...@google.com>
Acked-by: Neal Cardwell <ncardw...@google.com>
---
net/ipv4/tcp_output.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index
d212e4cbc68902e873afb4a12b43b467ccd6069b..c07990a35ff3bd9438d32c82863ef207c93bdb9e
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 (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);
+ /* "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);
+
cwnd_quota = tcp_cwnd_test(tp, skb);
if (!cwnd_quota) {
if (push_one == 2)
--
2.19.1.331.ge82ca0e54c-goog
