net/route: Add an eventhandler for rt_numfibs changes

The multicast routing code will start implementing per-FIB routing
tables.  As a part of this, it needs to be notified when the number of
FIBs changes, so that it can expand its tables.

Add an eventhandler for this purpose.

MFC after:	2 weeks
Sponsored by:	Stormshield
Sponsored by:	Klara, Inc.
Differential Revision:	https://reviews.freebsd.org/D55239

2 files changed, 9 insertions, 1 deletions

diff --git a/sys/net/route.h b/sys/net/route.h
index 49bb7abd9726..34df3297d6d4 100644
--- a/sys/net/route.h
+++ b/sys/net/route.h
@@ -32,6 +32,9 @@
 #ifndef _NET_ROUTE_H_
 #define _NET_ROUTE_H_
 
+#ifdef _KERNEL
+#include <sys/_eventhandler.h>
+#endif
 #include <net/vnet.h>
 
 /*
@@ -124,6 +127,9 @@ VNET_DECLARE(u_int, rt_add_addr_allfibs); /* Announce interfaces to all fibs */
 #define	V_fib_hash_outbound	VNET(fib_hash_outbound)
 VNET_DECLARE(u_int, fib_hash_outbound);
 
+typedef void (*rtnumfibs_change_t)(void *, uint32_t);
+EVENTHANDLER_DECLARE(rtnumfibs_change, rtnumfibs_change_t);
+
 /* Outbound flowid generation rules */
 #ifdef RSS
 #define fib4_calc_packet_hash		xps_proto_software_hash_v4
diff --git a/sys/net/route/route_tables.c b/sys/net/route/route_tables.c
index 749ef063e125..571f1db9c40d 100644
--- a/sys/net/route/route_tables.c
+++ b/sys/net/route/route_tables.c
@@ -33,10 +33,10 @@
  * Which is the new name for an in kernel routing (next hop) table.	*
  ***********************************************************************/
 
-#include <sys/cdefs.h>
 #include "opt_route.h"
 
 #include <sys/param.h>
+#include <sys/eventhandler.h>
 #include <sys/socket.h>
 #include <sys/systm.h>
 #include <sys/malloc.h>
@@ -268,6 +268,8 @@ grow_rtables(uint32_t num_tables)
 	old_rt_tables = V_rt_tables;
 	V_rt_tables = new_rt_tables;
 
+	EVENTHANDLER_INVOKE(rtnumfibs_change, num_tables);
+
 	/* Wait till all cpus see new pointers */
 	atomic_thread_fence_rel();
 	NET_EPOCH_WAIT();