tcp: provide earliest departure time in skb->tstamp

Switch internal TCP skb->skb_mstamp to skb->skb_mstamp_ns,
from usec units to nsec units.

Do not clear skb->tstamp before entering IP stacks in TX,
so that qdisc or devices can implement pacing based on the
earliest departure time instead of socket sk->sk_pacing_rate

Packets are fed with tcp_wstamp_ns, and following patch
will update tcp_wstamp_ns when both TCP and sch_fq switch to
the earliest departure time mechanism.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 7fdf222a0bdf..61023d50cd60 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -360,7 +360,7 @@ static void tcp_probe_timer(struct sock *sk)
          */
         start_ts = tcp_skb_timestamp(skb);
         if (!start_ts)
-                skb->skb_mstamp = tp->tcp_mstamp;
+                skb->skb_mstamp_ns = tp->tcp_wstamp_ns;
         else if (icsk->icsk_user_timeout &&
                  (s32)(tcp_time_stamp(tp) - start_ts) > icsk->icsk_user_timeout)
                 goto abort;