[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.c b/net/ipv4/tcp.c
index 7e740112b238..aff31427f525 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2014,7 +2014,7 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
 
 	if (tp->rx_opt.tstamp_ok)
 		info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
-	if (tp->rx_opt.sack_ok)
+	if (tcp_is_sack(tp))
 		info->tcpi_options |= TCPI_OPT_SACK;
 	if (tp->rx_opt.wscale_ok) {
 		info->tcpi_options |= TCPI_OPT_WSCALE;