Implement reference counting for ifmultiaddr, in_multi, and in6_multi

structures. Detect when ifnet instances are detached from the network
stack and perform appropriate cleanup to prevent memory leaks.

This has been implemented in such a way as to be backwards ABI compatible.
Kernel consumers are changed to use if_delmulti_ifma(); in_delmulti()
is unable to detect interface removal by design, as it performs searches
on structures which are removed with the interface.

With this architectural change, the panics FreeBSD users have experienced
with carp and pfsync should be resolved.

Obtained from:	p4 branch bms_netdev
Reviewed by:	andre
Sponsored by:	Garance A Drosehn
Idea from:	NetBSD
MFC after:	1 month

1 files changed, 1 insertions, 1 deletions

diff --git a/sys/netinet/in_var.h b/sys/netinet/in_var.h
index 7d22844fe513..7605199c8d88 100644
--- a/sys/netinet/in_var.h
+++ b/sys/netinet/in_var.h
@@ -165,6 +165,7 @@ struct in_multi {
 	u_int	inm_timer;		/* IGMP membership report timer */
 	u_int	inm_state;		/*  state of the membership */
 	struct	router_info *inm_rti;	/* router info*/
+	u_int	inm_refcount;		/* reference count */
 };
 
 #ifdef _KERNEL
@@ -248,7 +249,6 @@ struct	route;
 struct	in_multi *in_addmulti(struct in_addr *, struct ifnet *);
 void	in_delmulti(struct in_multi *);
 void	in_delmulti_locked(struct in_multi *);
-void	in_delmulti_ifp(struct ifnet *ifp);
 int	in_control(struct socket *, u_long, caddr_t, struct ifnet *,
 	    struct thread *);
 void	in_rtqdrain(void);