Do not check if found IPv4 rte is dynamic if net.inet.icmp.drop_redirect is

enabled. This eliminates one mtx_lock() per each routing lookup thus improving
performance in several cases (routing to directly connected interface or routing
to default gateway).

Icmp redirects should not be used to provide routing direction nowadays, even
for end hosts. Routers should not use them too (and this is explicitly restricted
in IPv6, see RFC 4861, clause 8.2).

Current commit changes rnh_machaddr function to 'stock' rn_match (and back) for every
AF_INET routing table in given VNET instance on drop_redirect sysctl change.

This change is part of bigger patch eliminating rte locking.

Sponsored by:	Yandex LLC
MFC after:	2 weeks

1 files changed, 10 insertions, 1 deletions

diff --git a/sys/netinet/in_rmx.c b/sys/netinet/in_rmx.c
index 1389873..80ec096 100644
--- a/sys/netinet/in_rmx.c
+++ b/sys/netinet/in_rmx.c
@@ -58,6 +58,8 @@ __FBSDID("$FreeBSD$");
 
 #include <netinet/in.h>
 #include <netinet/in_var.h>
+#include <netinet/ip.h>
+#include <netinet/ip_icmp.h>
 #include <netinet/ip_var.h>
 
 extern int	in_inithead(void **head, int off);
@@ -340,6 +342,13 @@ in_rtqdrain(void)
 	VNET_LIST_RUNLOCK_NOSLEEP();
 }
 
+void
+in_setmatchfunc(struct radix_node_head *rnh, int val)
+{
+
+	rnh->rnh_matchaddr = (val != 0) ? rn_match : in_matroute;
+}
+
 static int _in_rt_was_here;
 /*
  * Initialize our routing tree.
@@ -365,7 +374,7 @@ in_inithead(void **head, int off)
 
 	rnh = *head;
 	rnh->rnh_addaddr = in_addroute;
-	rnh->rnh_matchaddr = in_matroute;
+	in_setmatchfunc(rnh, V_drop_redirect);
 	rnh->rnh_close = in_clsroute;
 	if (_in_rt_was_here == 0 ) {
 		callout_init(&V_rtq_timer, CALLOUT_MPSAFE);