tcp: introduce tcp_rto_delta_us() helper for xmit timer fix

Pure refactor. This helper will be required in the xmit timer fix
later in the patch series. (Because the TLP logic will want to make
this calculation.)

Fixes: 6ba8a3b19e76 ("tcp: Tail loss probe (TLP)")
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 70483296157f87acdf5acd5e96eaa910119ba220..ada65e767b28dfcabb662a7b08f65c6fc04f5b73 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1916,6 +1916,16 @@ extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
                             u64 xmit_time);
 extern void tcp_rack_reo_timeout(struct sock *sk);
 
+/* At how many usecs into the future should the RTO fire? */
+static inline s64 tcp_rto_delta_us(const struct sock *sk)
+{
+       const struct sk_buff *skb = tcp_write_queue_head(sk);
+       u32 rto = inet_csk(sk)->icsk_rto;
+       u64 rto_time_stamp_us = skb->skb_mstamp + jiffies_to_usecs(rto);
+
+       return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
+}
+
 /*
  * Save and compile IPv4 options, return a pointer to it
  */

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index dad026fcfd098a78aab373bae78dbf88a0c50df1..b9ba8d55d8b8ef3ec38274bcaac0c6500c199594 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3004,10 +3004,7 @@ void tcp_rearm_rto(struct sock *sk)
                /* Offset the time elapsed after installing regular RTO */
                if (icsk->icsk_pending == ICSK_TIME_REO_TIMEOUT ||
                    icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
-                       struct sk_buff *skb = tcp_write_queue_head(sk);
-                       u64 rto_time_stamp = skb->skb_mstamp +
-                                            jiffies_to_usecs(rto);
-                       s64 delta_us = rto_time_stamp - tp->tcp_mstamp;
+                       s64 delta_us = tcp_rto_delta_us(sk);
                        /* delta_us may not be positive if the socket is locked
                         * when the retrans timer fires and is rescheduled.
                         */