tcp: replace tcp_time_stamp_raw()

In preparation of usec TCP TS support, remove tcp_time_stamp_raw()
in favor of tcp_clock_ts() helper. This helper will return a suitable
32bit result to feed TS values, depending on a socket field.

Also add tcp_tw_tsval() and tcp_rsk_tsval() helpers to factorize
the details.

We do not yet support usec timestamps.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/tcp.h

@@ -803,6 +803,16 @@ static inline u64 tcp_clock_ms(void)
 	return div_u64(tcp_clock_ns(), NSEC_PER_MSEC);
 }
 
+/* TCP Timestamp included in TS option (RFC 1323) can either use ms
+ * or usec resolution. Each socket carries a flag to select one or other
+ * resolution, as the route attribute could change anytime.
+ * Each flow must stick to initial resolution.
+ */
+static inline u32 tcp_clock_ts(bool usec_ts)
+{
+	return usec_ts ? tcp_clock_us() : tcp_clock_ms();
+}
+
 /* This should only be used in contexts where tp->tcp_mstamp is up to date */
 static inline u32 tcp_time_stamp(const struct tcp_sock *tp)
 {
@@ -820,12 +830,6 @@ static inline u64 tcp_ns_to_ts(u64 ns)
 	return div_u64(ns, NSEC_PER_SEC / TCP_TS_HZ);
 }
 
-/* Could use tcp_clock_us() / 1000, but this version uses a single divide */
-static inline u32 tcp_time_stamp_raw(void)
-{
-	return tcp_ns_to_ts(tcp_clock_ns());
-}
-
 void tcp_mstamp_refresh(struct tcp_sock *tp);
 
 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
@@ -844,6 +848,15 @@ static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb)
 	return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC);
 }
 
+static inline u32 tcp_tw_tsval(const struct tcp_timewait_sock *tcptw)
+{
+	return tcp_clock_ts(false) + tcptw->tw_ts_offset;
+}
+
+static inline u32 tcp_rsk_tsval(const struct tcp_request_sock *treq)
+{
+	return tcp_clock_ts(false) + treq->ts_off;
+}
 
 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
 

net/ipv4/tcp.c

@@ -3632,7 +3632,7 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
 		if (!tp->repair)
 			err = -EPERM;
 		else
-			WRITE_ONCE(tp->tsoffset, val - tcp_time_stamp_raw());
+			WRITE_ONCE(tp->tsoffset, val - tcp_clock_ts(false));
 		break;
 	case TCP_REPAIR_WINDOW:
 		err = tcp_repair_set_window(tp, optval, optlen);
@@ -4143,7 +4143,7 @@ int do_tcp_getsockopt(struct sock *sk, int level,
 		break;
 
 	case TCP_TIMESTAMP:
-		val = tcp_time_stamp_raw() + READ_ONCE(tp->tsoffset);
+		val = tcp_clock_ts(false) + READ_ONCE(tp->tsoffset);
 		break;
 	case TCP_NOTSENT_LOWAT:
 		val = READ_ONCE(tp->notsent_lowat);

net/ipv4/tcp_ipv4.c

@@ -954,7 +954,7 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
 	tcp_v4_send_ack(sk, skb,
 			tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
 			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
-			tcp_time_stamp_raw() + tcptw->tw_ts_offset,
+			tcp_tw_tsval(tcptw),
 			tcptw->tw_ts_recent,
 			tw->tw_bound_dev_if,
 			tcp_twsk_md5_key(tcptw),
@@ -988,7 +988,7 @@ static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 	tcp_v4_send_ack(sk, skb, seq,
 			tcp_rsk(req)->rcv_nxt,
 			req->rsk_rcv_wnd >> inet_rsk(req)->rcv_wscale,
-			tcp_time_stamp_raw() + tcp_rsk(req)->ts_off,
+			tcp_rsk_tsval(tcp_rsk(req)),
 			READ_ONCE(req->ts_recent),
 			0,
 			tcp_md5_do_lookup(sk, l3index, addr, AF_INET),

net/ipv6/tcp_ipv6.c

@@ -1096,7 +1096,7 @@ static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
 
 	tcp_v6_send_ack(sk, skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
 			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
-			tcp_time_stamp_raw() + tcptw->tw_ts_offset,
+			tcp_tw_tsval(tcptw),
 			tcptw->tw_ts_recent, tw->tw_bound_dev_if, tcp_twsk_md5_key(tcptw),
 			tw->tw_tclass, cpu_to_be32(tw->tw_flowlabel), tw->tw_priority,
 			tw->tw_txhash);
@@ -1123,7 +1123,7 @@ static void tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 			tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
 			tcp_rsk(req)->rcv_nxt,
 			req->rsk_rcv_wnd >> inet_rsk(req)->rcv_wscale,
-			tcp_time_stamp_raw() + tcp_rsk(req)->ts_off,
+			tcp_rsk_tsval(tcp_rsk(req)),
 			READ_ONCE(req->ts_recent), sk->sk_bound_dev_if,
 			tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->saddr, l3index),
 			ipv6_get_dsfield(ipv6_hdr(skb)), 0,