Re: [PATCH 1/1] tcp: Replace constants with #define macros

   to record the state of SACK/FACK and DSACK for better readability and maintenance.

Signed-off-by: Vijay Subramanian <redacted>
---
 include/linux/tcp.h   |    5 +++++
 include/net/tcp.h     |    4 ++--
 net/ipv4/syncookies.c |    2 +-
 net/ipv4/tcp_input.c  |    6 +++---
 4 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 7f59ee9..874b043 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h

@@ -238,6 +238,11 @@ struct tcp_sack_block {

       u32     end_seq;
 };

+/*These are used to set the sack_ok field in struct tcp_options_received */
+#define SACK_SEEN     (1 << 0)   /*1 = peer is SACK capable, */
+#define FACK_ENABLED  (1 << 1)   /*1 = FACK is enabled locally*/
+#define DSACK_SEEN    (1 << 2)   /*1 = DSACK was received from peer*/
+
 struct tcp_options_received {
 /*     PAWS/RTTM data  */
       long    ts_recent_stamp;/* Time we stored ts_recent (for aging) */

diff --git a/include/net/tcp.h b/include/net/tcp.h
index a4f52e1..cbb943e 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h

@@ -773,12 +773,12 @@ static inline int tcp_is_reno(const struct tcp_sock *tp)

 static inline int tcp_is_fack(const struct tcp_sock *tp)
 {
-       return tp->rx_opt.sack_ok & 2;
+       return tp->rx_opt.sack_ok & FACK_ENABLED;
 }

 static inline void tcp_enable_fack(struct tcp_sock *tp)
 {
-       tp->rx_opt.sack_ok |= 2;
+       tp->rx_opt.sack_ok |= FACK_ENABLED;
 }

 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)

diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 90f6544..dfba6a5 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c

@@ -245,7 +245,7 @@ bool cookie_check_timestamp(struct tcp_options_received *tcp_opt, bool *ecn_ok)

       if (!sysctl_tcp_timestamps)
               return false;

-       tcp_opt->sack_ok = (options >> 4) & 0x1;
+       tcp_opt->sack_ok = (options >> 4) & SACK_SEEN;
       *ecn_ok = (options >> 5) & 1;
       if (*ecn_ok && !sysctl_tcp_ecn)
               return false;

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index f131d92..5cbc788 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c

@@ -865,13 +865,13 @@ static void tcp_disable_fack(struct tcp_sock *tp)

       /* RFC3517 uses different metric in lost marker => reset on change */
       if (tcp_is_fack(tp))
               tp->lost_skb_hint = NULL;
-       tp->rx_opt.sack_ok &= ~2;
+       tp->rx_opt.sack_ok &= ~FACK_ENABLED;
 }

 /* Take a notice that peer is sending D-SACKs */
 static void tcp_dsack_seen(struct tcp_sock *tp)
 {
-       tp->rx_opt.sack_ok |= 4;
+       tp->rx_opt.sack_ok |= DSACK_SEEN;
 }

 /* Initialize metrics on socket. */

@@ -3878,7 +3878,7 @@ void tcp_parse_options(const struct sk_buff *skb, struct tcp_options_received *o

                       case TCPOPT_SACK_PERM:
                               if (opsize == TCPOLEN_SACK_PERM && th->syn &&
                                   !estab && sysctl_tcp_sack) {
-                                       opt_rx->sack_ok = 1;
+                                       opt_rx->sack_ok = SACK_SEEN;
                                       tcp_sack_reset(opt_rx);
                               }
                               break;
--
1.7.0.4