turn the linkstate hooks into a task list, like the detach hooks.

this is largely mechanical, except for carp. this moves the addition
of the carp link state hook after we're committed to using the new
interface as a carpdev. because the add can't fail, we avoid a
complicated unwind dance. also, this tweaks the carp linkstate hook
so it only updates the relevant carp interface, not all of the
carpdevs on the parent.

hrvoje popovski has tested an early version of this diff and it's
generally ok, but there's some splasserts that this diff fires that
i'll fix in an upcoming diff.

ok claudio@

1 files changed, 23 insertions, 8 deletions

diff --git a/sys/net/if.c b/sys/net/if.c
index 0f3e07a53d8..0c96e305224 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if.c,v 1.589 2019/11/06 03:51:26 dlg Exp $	*/
+/*	$OpenBSD: if.c,v 1.590 2019/11/07 07:36:31 dlg Exp $	*/
 /*	$NetBSD: if.c,v 1.35 1996/05/07 05:26:04 thorpej Exp $	*/
 
 /*
@@ -629,9 +629,7 @@ if_attach_common(struct ifnet *ifp)
 	ifp->if_addrhooks = malloc(sizeof(*ifp->if_addrhooks),
 	    M_TEMP, M_WAITOK);
 	TAILQ_INIT(ifp->if_addrhooks);
-	ifp->if_linkstatehooks = malloc(sizeof(*ifp->if_linkstatehooks),
-	    M_TEMP, M_WAITOK);
-	TAILQ_INIT(ifp->if_linkstatehooks);
+	TAILQ_INIT(&ifp->if_linkstatehooks);
 	TAILQ_INIT(&ifp->if_detachhooks);
 
 	if (ifp->if_rtrequest == NULL)
@@ -1055,8 +1053,6 @@ if_deactivate(struct ifnet *ifp)
 	NET_LOCK();
 	TAILQ_FOREACH_SAFE(t, &ifp->if_detachhooks, t_entry, nt)
 		(*t->t_func)(t->t_arg);
-
-	KASSERT(TAILQ_EMPTY(&ifp->if_detachhooks));
 	NET_UNLOCK();
 }
 
@@ -1148,7 +1144,8 @@ if_detach(struct ifnet *ifp)
 	}
 
 	free(ifp->if_addrhooks, M_TEMP, sizeof(*ifp->if_addrhooks));
-	free(ifp->if_linkstatehooks, M_TEMP, sizeof(*ifp->if_linkstatehooks));
+	KASSERT(TAILQ_EMPTY(&ifp->if_linkstatehooks));
+	KASSERT(TAILQ_EMPTY(&ifp->if_detachhooks));
 
 	for (i = 0; (dp = domains[i]) != NULL; i++) {
 		if (dp->dom_ifdetach && ifp->if_afdata[dp->dom_family])
@@ -1646,11 +1643,29 @@ if_linkstate_task(void *xifidx)
 void
 if_linkstate(struct ifnet *ifp)
 {
+	struct task *t, *nt;
+
 	NET_ASSERT_LOCKED();
 
 	rtm_ifchg(ifp);
 	rt_if_track(ifp);
-	dohooks(ifp->if_linkstatehooks, 0);
+
+	TAILQ_FOREACH_SAFE(t, &ifp->if_linkstatehooks, t_entry, nt)
+		(*t->t_func)(t->t_arg);
+}
+
+void
+if_linkstatehook_add(struct ifnet *ifp, struct task *t)
+{
+	NET_ASSERT_LOCKED();
+	TAILQ_INSERT_TAIL(&ifp->if_linkstatehooks, t, t_entry);
+}
+
+void
+if_linkstatehook_del(struct ifnet *ifp, struct task *t)
+{
+	NET_ASSERT_LOCKED();
+	TAILQ_REMOVE(&ifp->if_linkstatehooks, t, t_entry);
 }
 
 /*