PERFORCE change 129005 for review

[Marko Zec]

http://perforce.freebsd.org/chv.cgi?CH=129005

Change 129005 by zec at zec_tpx32 on 2007/11/13 00:24:48

	When detaching an ifnet, attempt to detach from any vlan,
	bridge, lagg or similar ifnets linked to us as early as
	possible.
	
	This fixes a panic that can be provoked as follows:
	
	ngctl mkpeer eiface ether ether
	ifconfig vlan create
	ifconfig vlan0 vlan 1 vlandev ngeth0
	ifconfig vlan0 10.0.0.1 up
	ngctl shut ngeth0:
	
	The panic is reproducible both in HEAD and vimage branch.
	
	Reported by: Nikos Vassiliadis <nvass at teledomenet.gr>

Affected files ...

.. //depot/projects/vimage/src/sys/net/if.c#22 edit

Differences ...

==== //depot/projects/vimage/src/sys/net/if.c#22 (text+ko) ====

@@ -766,6 +766,14 @@
  	struct ifnet *iter;
  	int found = 0;
 
+	/*
+	 * Detach from any vlan, bridge or lagg ifnets linked to us.
+	 * A small though unlikely window for a race from here to ifp
+	 * unlinking from ifnet list is possible, hence we repeat the
+	 * procedure once again further bellow.  XXX.
+	 */
+	EVENTHANDLER_INVOKE(ifnet_departure_event, ifp);
+
 	IFNET_WLOCK();
 	TAILQ_FOREACH(iter, &V_ifnet, if_link)
 		if (iter == ifp) {