commit dc6e0760fd72e3cafecc358e66690f6e0b97deee
Author: Ryota Ozaki <ozaki-r@iij.ad.jp>
Date:   Mon Jan 4 14:40:52 2016 +0900

    Apply a patch from mlelstv@
    
    Conflicts:
    	sys/net/if.c
    	sys/net/if.h

diff --git a/sys/net/if.c b/sys/net/if.c
index bd158bd..f047c00 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -200,6 +200,7 @@ static void if_attachdomain1(struct ifnet *);
 static int ifconf(u_long, void *);
 static int if_clone_create(const char *);
 static int if_clone_destroy(const char *);
+static void if_link_state_change_si(void *);
 
 struct if_percpuq {
 	struct ifnet	*ipq_ifp;
@@ -602,6 +603,7 @@ if_initialize(ifnet_t *ifp)
 	ifp->if_broadcastaddr = 0; /* reliably crash if used uninitialized */
 
 	ifp->if_link_state = LINK_STATE_UNKNOWN;
+	ifp->if_old_link_state = LINK_STATE_UNKNOWN;
 
 	ifp->if_capenable = 0;
 	ifp->if_csum_flags_tx = 0;
@@ -627,6 +629,10 @@ if_initialize(ifnet_t *ifp)
 
 	IF_AFDATA_LOCK_INIT(ifp);
 
+	ifp->if_link_si = softint_establish(SOFTINT_NET, if_link_state_change_si, ifp);
+	if (ifp->if_link_si == NULL)
+		panic("%s: softint_establish() failed", __func__);
+
 	if_getindex(ifp);
 }
 
@@ -1045,6 +1051,9 @@ again:
 
 	IF_AFDATA_LOCK_DESTROY(ifp);
 
+	softint_disestablish(ifp->if_link_si);
+	ifp->if_link_si = NULL;
+
 	/*
 	 * remove packets that came from ifp, from software interrupt queues.
 	 */
@@ -1562,8 +1571,6 @@ void
 if_link_state_change(struct ifnet *ifp, int link_state)
 {
 	int s;
-	int old_link_state;
-	struct domain *dp;
 
 	s = splnet();
 	if (ifp->if_link_state == link_state) {
@@ -1571,8 +1578,26 @@ if_link_state_change(struct ifnet *ifp, int link_state)
 		return;
 	}
 
-	old_link_state = ifp->if_link_state;
 	ifp->if_link_state = link_state;
+	softint_schedule(ifp->if_link_si);
+
+	splx(s);
+}
+
+
+static void
+if_link_state_change_si(void *arg)
+{
+	struct ifnet *ifp = arg;
+	int s;
+	int link_state, old_link_state;
+	struct domain *dp;
+
+	s = splnet();
+	link_state = ifp->if_link_state;
+	old_link_state = ifp->if_old_link_state;
+	ifp->if_old_link_state = ifp->if_link_state;
+
 #ifdef DEBUG
 	log(LOG_DEBUG, "%s: link state %s (was %s)\n", ifp->if_xname,
 		link_state == LINK_STATE_UP ? "UP" :
diff --git a/sys/net/if.h b/sys/net/if.h
index e85b29c..b0789de2 100644
--- a/sys/net/if.h
+++ b/sys/net/if.h
@@ -358,6 +358,8 @@ typedef struct ifnet {
 	struct krwlock	*if_afdata_lock;
 #endif
 	struct if_percpuq	*if_percpuq; /* We should remove it in the future */
+	void	*if_link_si;		/* softint to handle link state changes */
+	int	if_old_link_state;	/* previous link state */
 #endif
 } ifnet_t;