tcp: introduce tcp_skb_timestamp_us() helper

There are few places where TCP reads skb->skb_mstamp expecting
a value in usec unit.

skb->tstamp (aka skb->skb_mstamp) will soon store CLOCK_TAI nsec value.

Add tcp_skb_timestamp_us() to provide proper conversion when needed.

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

5 files changed, 19 insertions, 16 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index d9034073138c..d703a0b3b6a2 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1305,7 +1305,7 @@ static bool tcp_shifted_skb(struct sock *sk, struct sk_buff *prev,
          */
         tcp_sacktag_one(sk, state, TCP_SKB_CB(skb)->sacked,
                         start_seq, end_seq, dup_sack, pcount,
-                        skb->skb_mstamp);
+                        tcp_skb_timestamp_us(skb));
         tcp_rate_skb_delivered(sk, skb, state->rate);
 
         if (skb == tp->lost_skb_hint)
@@ -1580,7 +1580,7 @@ static struct sk_buff *tcp_sacktag_walk(struct sk_buff *skb, struct sock *sk,
                                                 TCP_SKB_CB(skb)->end_seq,
                                                 dup_sack,
                                                 tcp_skb_pcount(skb),
-                                                skb->skb_mstamp);
+                                                tcp_skb_timestamp_us(skb));
                         tcp_rate_skb_delivered(sk, skb, state->rate);
                         if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)
                                 list_del_init(&skb->tcp_tsorted_anchor);
@@ -3103,7 +3103,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, u32 prior_fack,
                                 tp->retrans_out -= acked_pcount;
                         flag |= FLAG_RETRANS_DATA_ACKED;
                 } else if (!(sacked & TCPCB_SACKED_ACKED)) {
-                        last_ackt = skb->skb_mstamp;
+                        last_ackt = tcp_skb_timestamp_us(skb);
                         WARN_ON_ONCE(last_ackt == 0);
                         if (!first_ackt)
                                 first_ackt = last_ackt;
@@ -3121,7 +3121,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, u32 prior_fack,
                         tp->delivered += acked_pcount;
                         if (!tcp_skb_spurious_retrans(tp, skb))
                                 tcp_rack_advance(tp, sacked, scb->end_seq,
-                                                 skb->skb_mstamp);
+                                                 tcp_skb_timestamp_us(skb));
                 }
                 if (sacked & TCPCB_LOST)
                         tp->lost_out -= acked_pcount;
@@ -3215,7 +3215,8 @@ static int tcp_clean_rtx_queue(struct sock *sk, u32 prior_fack,
                         tp->lost_cnt_hint -= min(tp->lost_cnt_hint, delta);
                 }
         } else if (skb && rtt_update && sack_rtt_us >= 0 &&
-                   sack_rtt_us > tcp_stamp_us_delta(tp->tcp_mstamp, skb->skb_mstamp)) {
+                   sack_rtt_us > tcp_stamp_us_delta(tp->tcp_mstamp,
+                                                    tcp_skb_timestamp_us(skb))) {
                 /* Do not re-arm RTO if the sack RTT is measured from data sent
                  * after when the head was last (re)transmitted. Otherwise the
                  * timeout may continue to extend in loss recovery.
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 09547ef9c4c6..1f2496e8620d 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -544,7 +544,7 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
                 BUG_ON(!skb);
 
                 tcp_mstamp_refresh(tp);
-                delta_us = (u32)(tp->tcp_mstamp - skb->skb_mstamp);
+                delta_us = (u32)(tp->tcp_mstamp - tcp_skb_timestamp_us(skb));
                 remaining = icsk->icsk_rto -
                             usecs_to_jiffies(delta_us);
 
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 597dbd749f05..b95aa72d8823 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1966,7 +1966,7 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
         head = tcp_rtx_queue_head(sk);
         if (!head)
                 goto send_now;
-        age = tcp_stamp_us_delta(tp->tcp_mstamp, head->skb_mstamp);
+        age = tcp_stamp_us_delta(tp->tcp_mstamp, tcp_skb_timestamp_us(head));
         /* If next ACK is likely to come too late (half srtt), do not defer */
         if (age < (tp->srtt_us >> 4))
                 goto send_now;
diff --git a/net/ipv4/tcp_rate.c b/net/ipv4/tcp_rate.c
index 4dff40dad4dc..baed2186c7c6 100644
--- a/net/ipv4/tcp_rate.c
+++ b/net/ipv4/tcp_rate.c
@@ -55,8 +55,10 @@ void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb)
           * bandwidth estimate.
           */
         if (!tp->packets_out) {
-                tp->first_tx_mstamp  = skb->skb_mstamp;
-                tp->delivered_mstamp = skb->skb_mstamp;
+                u64 tstamp_us = tcp_skb_timestamp_us(skb);
+
+                tp->first_tx_mstamp  = tstamp_us;
+                tp->delivered_mstamp = tstamp_us;
         }
 
         TCP_SKB_CB(skb)->tx.first_tx_mstamp     = tp->first_tx_mstamp;
@@ -88,13 +90,12 @@ void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
                 rs->is_app_limited   = scb->tx.is_app_limited;
                 rs->is_retrans       = scb->sacked & TCPCB_RETRANS;
 
+                /* Record send time of most recently ACKed packet: */
+                tp->first_tx_mstamp  = tcp_skb_timestamp_us(skb);
                 /* Find the duration of the "send phase" of this window: */
-                rs->interval_us      = tcp_stamp_us_delta(
-                                                skb->skb_mstamp,
-                                                scb->tx.first_tx_mstamp);
+                rs->interval_us = tcp_stamp_us_delta(tp->first_tx_mstamp,
+                                                     scb->tx.first_tx_mstamp);
 
-                /* Record send time of most recently ACKed packet: */
-                tp->first_tx_mstamp  = skb->skb_mstamp;
         }
         /* Mark off the skb delivered once it's sacked to avoid being
          * used again when it's cumulatively acked. For acked packets
diff --git a/net/ipv4/tcp_recovery.c b/net/ipv4/tcp_recovery.c
index c81aadff769b..fdb715bdd2d1 100644
--- a/net/ipv4/tcp_recovery.c
+++ b/net/ipv4/tcp_recovery.c
@@ -50,7 +50,7 @@ static u32 tcp_rack_reo_wnd(const struct sock *sk)
 s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb, u32 reo_wnd)
 {
         return tp->rack.rtt_us + reo_wnd -
-               tcp_stamp_us_delta(tp->tcp_mstamp, skb->skb_mstamp);
+               tcp_stamp_us_delta(tp->tcp_mstamp, tcp_skb_timestamp_us(skb));
 }
 
 /* RACK loss detection (IETF draft draft-ietf-tcpm-rack-01):
@@ -91,7 +91,8 @@ static void tcp_rack_detect_loss(struct sock *sk, u32 *reo_timeout)
                     !(scb->sacked & TCPCB_SACKED_RETRANS))
                         continue;
 
-                if (!tcp_rack_sent_after(tp->rack.mstamp, skb->skb_mstamp,
+                if (!tcp_rack_sent_after(tp->rack.mstamp,
+                                         tcp_skb_timestamp_us(skb),
                                          tp->rack.end_seq, scb->end_seq))
                         break;