tcp: keepalive cleanups

Introduce keepalive_probes(tp) helper, and use it, like 
keepalive_time_when(tp) and keepalive_intvl_when(tp)
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/tcp.h

@@ -1007,6 +1007,11 @@ static inline int keepalive_time_when(const struct tcp_sock *tp)
 	return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
 }
 
+static inline int keepalive_probes(const struct tcp_sock *tp)
+{
+	return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
+}
+
 static inline int tcp_fin_time(const struct sock *sk)
 {
 	int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;

net/ipv4/tcp.c

@@ -2336,13 +2336,13 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
 		val = !!(tp->nonagle&TCP_NAGLE_CORK);
 		break;
 	case TCP_KEEPIDLE:
-		val = (tp->keepalive_time ? : sysctl_tcp_keepalive_time) / HZ;
+		val = keepalive_time_when(tp) / HZ;
 		break;
 	case TCP_KEEPINTVL:
-		val = (tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl) / HZ;
+		val = keepalive_intvl_when(tp) / HZ;
 		break;
 	case TCP_KEEPCNT:
-		val = tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
+		val = keepalive_probes(tp);
 		break;
 	case TCP_SYNCNT:
 		val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;

net/ipv4/tcp_timer.c

@@ -499,8 +499,7 @@ static void tcp_keepalive_timer (unsigned long data)
 	elapsed = tcp_time_stamp - tp->rcv_tstamp;
 
 	if (elapsed >= keepalive_time_when(tp)) {
-		if ((!tp->keepalive_probes && icsk->icsk_probes_out >= sysctl_tcp_keepalive_probes) ||
-		     (tp->keepalive_probes && icsk->icsk_probes_out >= tp->keepalive_probes)) {
+		if (icsk->icsk_probes_out >= keepalive_probes(tp)) {
 			tcp_send_active_reset(sk, GFP_ATOMIC);
 			tcp_write_err(sk);
 			goto out;