Untangle the net.inet.tcp.log_in_vain and net.inet.tcp.log_debug

sysctl's and remove any side effects.

Both sysctl's share the same backend infrastructure and due to the
way it was implemented enabling net.inet.tcp.log_in_vain would also
cause log_debug output to be generated.  This was surprising and
eventually annoying to the user.

The log output backend is kept the same but a little shim is inserted
to properly separate log_in_vain and log_debug and to remove any side
effects.

PR:		kern/137317
MFC after:	1 week

1 files changed, 26 insertions, 4 deletions

diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
index f23a540..fe8f79a 100644
--- a/sys/netinet/tcp_subr.c
+++ b/sys/netinet/tcp_subr.c
@@ -268,6 +268,8 @@ VNET_DEFINE(uma_zone_t, sack_hole_zone);
 
 static struct inpcb *tcp_notify(struct inpcb *, int);
 static void	tcp_isn_tick(void *);
+static char *	tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th,
+		    void *ip4hdr, const void *ip6hdr);
 
 /*
  * Target size of TCP PCB hash tables. Must be a power of two.
@@ -2234,9 +2236,33 @@ SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop,
  * and ip6_hdr pointers have to be passed as void pointers.
  */
 char *
+tcp_log_vain(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
+    const void *ip6hdr)
+{
+
+	/* Is logging enabled? */
+	if (tcp_log_in_vain == 0)
+		return (NULL);
+
+	return (tcp_log_addr(inc, th, ip4hdr, ip6hdr));
+}
+
+char *
 tcp_log_addrs(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
     const void *ip6hdr)
 {
+
+	/* Is logging enabled? */
+	if (tcp_log_debug == 0)
+		return (NULL);
+
+	return (tcp_log_addr(inc, th, ip4hdr, ip6hdr));
+}
+
+static char *
+tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
+    const void *ip6hdr)
+{
 	char *s, *sp;
 	size_t size;
 	struct ip *ip;
@@ -2259,10 +2285,6 @@ tcp_log_addrs(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
 	    2 * INET_ADDRSTRLEN;
 #endif /* INET6 */
 
-	/* Is logging enabled? */
-	if (tcp_log_debug == 0 && tcp_log_in_vain == 0)
-		return (NULL);
-
 	s = malloc(size, M_TCPLOG, M_ZERO|M_NOWAIT);
 	if (s == NULL)
 		return (NULL);