Change vlan interfaces to cope more usefully with the parent interface being

renamed.  Previously the vlan interfaces would lose their configuration as if
the parent interface had been physically removed.  Now vlan interfaces ignore
rename events.
- Add a new ifnet flag (IFF_RENAMING) that is set while an ifnet is being
  renamed.  This flag can be checked in ifnet departure/arrival event
  handlers to treat rename events differently.
- Change the ifnet departure event handler in the if_vlan(4) driver to
  ignore departure events due to a trunk interface being renamed.

Reviewed by:	brooks, rwatson
MFC after:	1 week

1 files changed, 10 insertions, 0 deletions

diff --git a/sys/net/if.c b/sys/net/if.c
index 003f3ea..7029b9c 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -2095,6 +2095,14 @@ ifhwioctl(u_long cmd, struct ifnet *ifp, caddr_t data, struct thread *td)
 			return (EINVAL);
 		if (ifunit(new_name) != NULL)
 			return (EEXIST);
+
+		/*
+		 * XXX: Locking.  Nothing else seems to lock if_flags,
+		 * and there are numerous other races with the
+		 * ifunit() checks not being atomic with namespace
+		 * changes (renames, vmoves, if_attach, etc).
+		 */
+		ifp->if_flags |= IFF_RENAMING;
 		
 		/* Announce the departure of the interface. */
 		rt_ifannouncemsg(ifp, IFAN_DEPARTURE);
@@ -2129,6 +2137,8 @@ ifhwioctl(u_long cmd, struct ifnet *ifp, caddr_t data, struct thread *td)
 		EVENTHANDLER_INVOKE(ifnet_arrival_event, ifp);
 		/* Announce the return of the interface. */
 		rt_ifannouncemsg(ifp, IFAN_ARRIVAL);
+
+		ifp->if_flags &= ~IFF_RENAMING;
 		break;
 
 #ifdef VIMAGE