tcp: add tcp_rtt_tsopt_us()

Before adding usec TS support, add tcp_rtt_tsopt_us() helper
to factorize code.

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

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index e7e38fc1d62ff16d7afd7f2ba58a1990f01e17b6..5666f61371678ce1c7bf466e0d54c0b7a396841b 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -693,6 +693,21 @@ new_measure:
        tp->rcv_rtt_est.time = tp->tcp_mstamp;
 }
 
+static s32 tcp_rtt_tsopt_us(const struct tcp_sock *tp)
+{
+       u32 delta, delta_us;
+
+       delta = tcp_time_stamp_ts(tp) - tp->rx_opt.rcv_tsecr;
+
+       if (likely(delta < INT_MAX / (USEC_PER_SEC / TCP_TS_HZ))) {
+               if (!delta)
+                       delta = 1;
+               delta_us = delta * (USEC_PER_SEC / TCP_TS_HZ);
+               return delta_us;
+       }
+       return -1;
+}
+
 static inline void tcp_rcv_rtt_measure_ts(struct sock *sk,
                                          const struct sk_buff *skb)
 {
@@ -704,15 +719,10 @@ static inline void tcp_rcv_rtt_measure_ts(struct sock *sk,
 
        if (TCP_SKB_CB(skb)->end_seq -
            TCP_SKB_CB(skb)->seq >= inet_csk(sk)->icsk_ack.rcv_mss) {
-               u32 delta = tcp_time_stamp_ts(tp) - tp->rx_opt.rcv_tsecr;
-               u32 delta_us;
-
-               if (likely(delta < INT_MAX / (USEC_PER_SEC / TCP_TS_HZ))) {
-                       if (!delta)
-                               delta = 1;
-                       delta_us = delta * (USEC_PER_SEC / TCP_TS_HZ);
-                       tcp_rcv_rtt_update(tp, delta_us, 0);
-               }
+               s32 delta = tcp_rtt_tsopt_us(tp);
+
+               if (delta >= 0)
+                       tcp_rcv_rtt_update(tp, delta, 0);
        }
 }
 
@@ -3146,17 +3156,10 @@ static bool tcp_ack_update_rtt(struct sock *sk, const int flag,
         * left edge of the send window.
         * See draft-ietf-tcplw-high-performance-00, section 3.3.
         */
-       if (seq_rtt_us < 0 && tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
-           flag & FLAG_ACKED) {
-               u32 delta = tcp_time_stamp_ts(tp) - tp->rx_opt.rcv_tsecr;
-
-               if (likely(delta < INT_MAX / (USEC_PER_SEC / TCP_TS_HZ))) {
-                       if (!delta)
-                               delta = 1;
-                       seq_rtt_us = delta * (USEC_PER_SEC / TCP_TS_HZ);
-                       ca_rtt_us = seq_rtt_us;
-               }
-       }
+       if (seq_rtt_us < 0 && tp->rx_opt.saw_tstamp &&
+           tp->rx_opt.rcv_tsecr && flag & FLAG_ACKED)
+               seq_rtt_us = ca_rtt_us = tcp_rtt_tsopt_us(tp);
+
        rs->rtt_us = ca_rtt_us; /* RTT of last (S)ACKed packet (or -1) */
        if (seq_rtt_us < 0)
                return false;