[TCP]: Move sack_ok access to obviously named funcs & cleanup

Previously code had IsReno/IsFack defined as macros that were
local to tcp_input.c though sack_ok field has user elsewhere too
for the same purpose. This changes them to static inlines as
preferred according the current coding style and unifies the
access to sack_ok across multiple files. Magic bitops of sack_ok
for FACK and DSACK are also abstracted to functions with
appropriate names.

Note:
- One sack_ok = 1 remains but that's self explanary, i.e., it
  enables sack
- Couple of !IsReno cases are changed to tcp_is_sack
- There were no users for IsDSack => I dropped it

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index e9b151b3a598..d8970ecfcfc8 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -315,7 +315,7 @@ static void tcp_retransmit_timer(struct sock *sk)
         if (icsk->icsk_retransmits == 0) {
                 if (icsk->icsk_ca_state == TCP_CA_Disorder ||
                     icsk->icsk_ca_state == TCP_CA_Recovery) {
-                        if (tp->rx_opt.sack_ok) {
+                        if (tcp_is_sack(tp)) {
                                 if (icsk->icsk_ca_state == TCP_CA_Recovery)
                                         NET_INC_STATS_BH(LINUX_MIB_TCPSACKRECOVERYFAIL);
                                 else