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>

1 files changed, 1 insertions, 4 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index dad026fcfd09..b9ba8d55d8b8 100644
--- 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.
                          */