[PATCH net-next 7/8] tcp: new helper tcp_rack_skb_timeout

[Yuchung Cheng <ycheng@google.com>]

Create and export a new helper tcp_rack_skb_timeout and move tcp_is_rack
to prepare the final RTO change.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Priyaranjan Jha <priyarjha@google.com>
---
 include/net/tcp.h       |  2 ++
 net/ipv4/tcp_input.c    | 10 +++++-----
 net/ipv4/tcp_recovery.c |  9 +++++++--
 3 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 402484ed9b57..b46d0f9adbdb 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1880,6 +1880,8 @@ void tcp_init(void);
 /* tcp_recovery.c */
 void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb);
 void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced);
+extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,
+				u32 reo_wnd);
 extern void tcp_rack_mark_lost(struct sock *sk);
 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
 			     u64 xmit_time);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 1ccc97b368c7..ba8a8e3464aa 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1917,6 +1917,11 @@ static inline void tcp_init_undo(struct tcp_sock *tp)
 	tp->undo_retrans = tp->retrans_out ? : -1;
 }
 
+static bool tcp_is_rack(const struct sock *sk)
+{
+	return sock_net(sk)->ipv4.sysctl_tcp_recovery & TCP_RACK_LOSS_DETECTION;
+}
+
 /* If we detect SACK reneging, forget all SACK information
  * and reset tags completely, otherwise preserve SACKs. If receiver
  * dropped its ofo queue, we will know this due to reneging detection.
@@ -2031,11 +2036,6 @@ static inline int tcp_dupack_heuristics(const struct tcp_sock *tp)
 	return tp->sacked_out + 1;
 }
 
-static bool tcp_is_rack(const struct sock *sk)
-{
-	return sock_net(sk)->ipv4.sysctl_tcp_recovery & TCP_RACK_LOSS_DETECTION;
-}
-
 /* Linux NewReno/SACK/ECN state machine.
  * --------------------------------------
  *
diff --git a/net/ipv4/tcp_recovery.c b/net/ipv4/tcp_recovery.c
index b2f9be388bf3..30cbfb69b1de 100644
--- a/net/ipv4/tcp_recovery.c
+++ b/net/ipv4/tcp_recovery.c
@@ -47,6 +47,12 @@ u32 tcp_rack_reo_wnd(const struct sock *sk)
 		   tp->srtt_us >> 3);
 }
 
+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);
+}
+
 /* RACK loss detection (IETF draft draft-ietf-tcpm-rack-01):
  *
  * Marks a packet lost, if some packet sent later has been (s)acked.
@@ -92,8 +98,7 @@ static void tcp_rack_detect_loss(struct sock *sk, u32 *reo_timeout)
 		/* A packet is lost if it has not been s/acked beyond
 		 * the recent RTT plus the reordering window.
 		 */
-		remaining = tp->rack.rtt_us + reo_wnd -
-			    tcp_stamp_us_delta(tp->tcp_mstamp, skb->skb_mstamp);
+		remaining = tcp_rack_skb_timeout(tp, skb, reo_wnd);
 		if (remaining <= 0) {
 			tcp_mark_skb_lost(sk, skb);
 			list_del_init(&skb->tcp_tsorted_anchor);
-- 
2.17.0.441.gb46fe60e1d-goog