Index: head/sys/net/if_bridge.c
===================================================================
--- head/sys/net/if_bridge.c
+++ head/sys/net/if_bridge.c
@@ -909,14 +909,18 @@
 		mask &= bif->bif_savedcaps;
 	}
 
+	BRIDGE_XLOCK(sc);
 	LIST_FOREACH(bif, &sc->sc_iflist, bif_next) {
 		enabled = bif->bif_ifp->if_capenable;
 		enabled &= ~BRIDGE_IFCAPS_STRIP;
 		/* strip off mask bits and enable them again if allowed */
 		enabled &= ~BRIDGE_IFCAPS_MASK;
 		enabled |= mask;
+		BRIDGE_UNLOCK(sc);
 		bridge_set_ifcap(sc, bif, enabled);
+		BRIDGE_LOCK(sc);
 	}
+	BRIDGE_XDROP(sc);
 
 }
 
@@ -927,6 +931,8 @@
 	struct ifreq ifr;
 	int error;
 
+	BRIDGE_UNLOCK_ASSERT(sc);
+
 	bzero(&ifr, sizeof(ifr));
 	ifr.ifr_reqcap = set;
 
Index: head/sys/net/if_bridgevar.h
===================================================================
--- head/sys/net/if_bridgevar.h
+++ head/sys/net/if_bridgevar.h
@@ -280,6 +280,7 @@
 #define BRIDGE_LOCK(_sc)		mtx_lock(&(_sc)->sc_mtx)
 #define BRIDGE_UNLOCK(_sc)		mtx_unlock(&(_sc)->sc_mtx)
 #define BRIDGE_LOCK_ASSERT(_sc)		mtx_assert(&(_sc)->sc_mtx, MA_OWNED)
+#define BRIDGE_UNLOCK_ASSERT(_sc)	mtx_assert(&(_sc)->sc_mtx, MA_NOTOWNED)
 #define	BRIDGE_LOCK2REF(_sc, _err)	do {	\
 	mtx_assert(&(_sc)->sc_mtx, MA_OWNED);	\
 	if ((_sc)->sc_iflist_xcnt > 0)		\