[TCP]: congestion control API pass RTT in microseconds

This patch changes the API for the callback that is done after an ACK is
received. It solves a couple of issues:

  * Some congestion controls want higher resolution value of RTT
    (controlled by TCP_CONG_RTT_SAMPLE flag). These don't really want a ktime, but
    all compute a RTT in microseconds.

  * Other congestion control could use RTT at jiffies resolution.

To keep API consistent the units should be the same for both cases, just the
resolution should change.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 3 deletions

diff --git a/net/ipv4/tcp_lp.c b/net/ipv4/tcp_lp.c
index 80e140e3ec2d..e7f5ef92cbd8 100644
--- a/net/ipv4/tcp_lp.c
+++ b/net/ipv4/tcp_lp.c
@@ -260,13 +260,13 @@ static void tcp_lp_rtt_sample(struct sock *sk, u32 rtt)
  * newReno in increase case.
  * We work it out by following the idea from TCP-LP's paper directly
  */
-static void tcp_lp_pkts_acked(struct sock *sk, u32 num_acked, ktime_t last)
+static void tcp_lp_pkts_acked(struct sock *sk, u32 num_acked, s32 rtt_us)
 {
         struct tcp_sock *tp = tcp_sk(sk);
         struct lp *lp = inet_csk_ca(sk);
 
-        if (!ktime_equal(last, net_invalid_timestamp()))
-                tcp_lp_rtt_sample(sk,  ktime_to_us(net_timedelta(last)));
+        if (rtt_us > 0)
+                tcp_lp_rtt_sample(sk, rtt_us);
 
         /* calc inference */
         if (tcp_time_stamp > tp->rx_opt.rcv_tsecr)