[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, 3 insertions, 3 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index a92fad55cd3..a3679174e78 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -737,7 +737,7 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss
 
                 if (diff > 0) {
                         /* Adjust Reno SACK estimate. */
-                        if (!tp->rx_opt.sack_ok) {
+                        if (tcp_is_reno(tp)) {
                                 tcp_dec_pcount_approx_int(&tp->sacked_out, diff);
                                 tcp_verify_left_out(tp);
                         }
@@ -1728,7 +1728,7 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int m
                 if (TCP_SKB_CB(next_skb)->sacked&TCPCB_LOST)
                         tp->lost_out -= tcp_skb_pcount(next_skb);
                 /* Reno case is special. Sigh... */
-                if (!tp->rx_opt.sack_ok && tp->sacked_out)
+                if (tcp_is_reno(tp) && tp->sacked_out)
                         tcp_dec_pcount_approx(&tp->sacked_out, next_skb);
 
                 /* Not quite right: it can be > snd.fack, but
@@ -1976,7 +1976,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
                 return;
 
         /* No forward retransmissions in Reno are possible. */
-        if (!tp->rx_opt.sack_ok)
+        if (tcp_is_reno(tp))
                 return;
 
         /* Yeah, we have to make difficult choice between forward transmission