Avoid INVARIANTS panic destroying an in-use tap(4)

The requirement (implied by the KASSERT in tap_destroy) that the tap is
closed isn't valid; destroy_dev will block in devdrn while other threads
are in d_* functions.

Note: if_tun had the same issue, addressed in SVN revisions r186391,
r186483 and r186497.  The use of the condvar there appears to be
redundant with the functionality provided by destroy_dev.

Sponsored by:	ADARA Networks
Reviewed by:	dwhite
MFC after:	2 weeks

1 files changed, 1 insertions, 5 deletions

diff --git a/sys/net/if_tap.c b/sys/net/if_tap.c
index 201f976..7052fea 100644
--- a/sys/net/if_tap.c
+++ b/sys/net/if_tap.c
@@ -213,14 +213,10 @@ tap_destroy(struct tap_softc *tp)
 {
 	struct ifnet *ifp = tp->tap_ifp;
 
-	/* Unlocked read. */
-	KASSERT(!(tp->tap_flags & TAP_OPEN),
-		("%s flags is out of sync", ifp->if_xname));
-
 	CURVNET_SET(ifp->if_vnet);
+	destroy_dev(tp->tap_dev);
 	seldrain(&tp->tap_rsel);
 	knlist_destroy(&tp->tap_rsel.si_note);
-	destroy_dev(tp->tap_dev);
 	ether_ifdetach(ifp);
 	if_free(ifp);