move the if input handler list to an SRP list.

instead of having every driver that manipulates the ifih list
understand SRPLs, this moves that processing into if_ih_insert and
if_ih_remove functions.

we rely on the kernel lock to serialise the modifications to the
list.

tested by mpi@
ok mpi@ claudio@ mikeb@

8 files changed, 121 insertions, 83 deletions

diff --git a/sys/net/if.c b/sys/net/if.c
index 77791b35b1f..30c09edb91d 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if.c,v 1.365 2015/09/10 06:00:37 dlg Exp $	*/
+/*	$OpenBSD: if.c,v 1.366 2015/09/10 13:32:19 dlg Exp $	*/
 /*	$NetBSD: if.c,v 1.35 1996/05/07 05:26:04 thorpej Exp $	*/
 
 /*
@@ -80,6 +80,7 @@
 #include <sys/domain.h>
 #include <sys/sysctl.h>
 #include <sys/task.h>
+#include <sys/proc.h>
 #include <sys/atomic.h>
 
 #include <dev/rndvar.h>
@@ -388,7 +389,7 @@ if_attach_common(struct ifnet *ifp)
 	ifp->if_linkstatetask = malloc(sizeof(*ifp->if_linkstatetask),
 	    M_TEMP, M_WAITOK|M_ZERO);
 
-	SLIST_INIT(&ifp->if_inputs);
+	SRPL_INIT(&ifp->if_inputs);
 }
 
 void
@@ -485,6 +486,93 @@ if_input(struct ifnet *ifp, struct mbuf_list *ml)
 	task_add(softnettq, &if_input_task);
 }
 
+struct ifih {
+	struct srpl_entry	  ifih_next;
+	int			(*ifih_input)(struct ifnet *, struct mbuf *);
+	int			  ifih_refcnt;
+	int			  ifih_srpcnt;
+};
+
+void	if_ih_ref(void *, void *);
+void	if_ih_unref(void *, void *);
+
+struct srpl_rc ifih_rc = SRPL_RC_INITIALIZER(if_ih_ref, if_ih_unref, NULL);
+
+void
+if_ih_insert(struct ifnet *ifp, int (*input)(struct ifnet *, struct mbuf *))
+{
+	struct ifih *ifih;
+
+	/* the kernel lock guarantees serialised modifications to if_inputs */
+	KERNEL_ASSERT_LOCKED();
+
+	SRPL_FOREACH_LOCKED(ifih, &ifp->if_inputs, ifih_next) {
+		if (ifih->ifih_input == input) {
+			ifih->ifih_refcnt++;
+			break;
+		}
+	}
+
+	if (ifih == NULL) {
+		ifih = malloc(sizeof(*ifih), M_DEVBUF, M_WAITOK);
+
+		ifih->ifih_input = input;
+		ifih->ifih_refcnt = 1;
+		ifih->ifih_srpcnt = 0;
+		SRPL_INSERT_HEAD_LOCKED(&ifih_rc, &ifp->if_inputs,
+		    ifih, ifih_next);
+	}
+}
+
+void
+if_ih_ref(void *null, void *i)
+{
+	struct ifih *ifih = i;
+
+	atomic_inc_int(&ifih->ifih_srpcnt);
+}
+
+void
+if_ih_unref(void *null, void *i)
+{
+	struct ifih *ifih = i;
+
+	if (atomic_dec_int_nv(&ifih->ifih_srpcnt) == 0)
+		wakeup_one(&ifih->ifih_srpcnt);
+}
+
+void
+if_ih_remove(struct ifnet *ifp, int (*input)(struct ifnet *, struct mbuf *))
+{
+	struct sleep_state sls;
+	struct ifih *ifih;
+	int refs;
+
+	/* the kernel lock guarantees serialised modifications to if_inputs */
+	KERNEL_ASSERT_LOCKED();
+
+	SRPL_FOREACH_LOCKED(ifih, &ifp->if_inputs, ifih_next) {
+		if (ifih->ifih_input == input)
+			break;
+	}
+
+	KASSERT(ifih != NULL);
+
+	if (--ifih->ifih_refcnt == 0) {
+		SRPL_REMOVE_LOCKED(&ifih_rc, &ifp->if_inputs, ifih,
+		    ifih, ifih_next);
+
+		refs = ifih->ifih_srpcnt;
+		while (refs) {
+			sleep_setup(&sls, &ifih->ifih_srpcnt, PWAIT, "ifihrm");
+			refs = ifih->ifih_srpcnt;
+			sleep_finish(&sls, refs);
+		}
+
+		free(ifih, M_DEVBUF, sizeof(*ifih));
+	}
+}
+
 void
 if_input_process(void *xmq)
 {
@@ -493,6 +581,7 @@ if_input_process(void *xmq)
 	struct mbuf *m;
 	struct ifnet *ifp;
 	struct ifih *ifih;
+	struct srpl_iter i;
 	int s;
 
 	mq_delist(mq, &ml);
@@ -525,10 +614,12 @@ if_input_process(void *xmq)
 		 * Pass this mbuf to all input handlers of its
 		 * interface until it is consumed.
 		 */
-		SLIST_FOREACH(ifih, &ifp->if_inputs, ifih_next) {
+		SRPL_FOREACH(ifih, &ifp->if_inputs, &i, ifih_next) {
 			if ((*ifih->ifih_input)(ifp, m))
 				break;
 		}
+		SRPL_LEAVE(&i, ifih);
+
 		if (ifih == NULL)
 			m_freem(m);
 	}
diff --git a/sys/net/if_bridge.c b/sys/net/if_bridge.c
index 756fcb899d0..770cf32fe4d 100644
--- a/sys/net/if_bridge.c
+++ b/sys/net/if_bridge.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_bridge.c,v 1.261 2015/09/09 12:50:08 mpi Exp $	*/
+/*	$OpenBSD: if_bridge.c,v 1.262 2015/09/10 13:32:19 dlg Exp $	*/
 
 /*
  * Copyright (c) 1999, 2000 Jason L. Wright (jason@thought.net)
@@ -183,7 +183,6 @@ int
 bridge_clone_create(struct if_clone *ifc, int unit)
 {
 	struct bridge_softc *sc;
-	struct ifih *bridge_ifih;
 	struct ifnet *ifp;
 	int i;
 
@@ -191,15 +190,8 @@ bridge_clone_create(struct if_clone *ifc, int unit)
 	if (!sc)
 		return (ENOMEM);
 
-	bridge_ifih = malloc(sizeof(*bridge_ifih), M_DEVBUF, M_NOWAIT);
-	if (bridge_ifih == NULL) {
-		free(sc, M_DEVBUF, 0);
-		return (ENOMEM);
-	}
-
 	sc->sc_stp = bstp_create(&sc->sc_if);
 	if (!sc->sc_stp) {
-		free(bridge_ifih, M_DEVBUF, sizeof(*bridge_ifih));
 		free(sc, M_DEVBUF, 0);
 		return (ENOMEM);
 	}
@@ -231,8 +223,7 @@ bridge_clone_create(struct if_clone *ifc, int unit)
 	    DLT_EN10MB, ETHER_HDR_LEN);
 #endif
 
-	bridge_ifih->ifih_input = ether_input;
-	SLIST_INSERT_HEAD(&ifp->if_inputs, bridge_ifih, ifih_next);
+	if_ih_insert(ifp, ether_input);
 
 	return (0);
 }
@@ -242,7 +233,6 @@ bridge_clone_destroy(struct ifnet *ifp)
 {
 	struct bridge_softc *sc = ifp->if_softc;
 	struct bridge_iflist *bif;
-	struct ifih *bridge_ifih;
 
 	bridge_stop(sc);
 	bridge_rtflush(sc, IFBF_FLUSHALL);
@@ -258,12 +248,9 @@ bridge_clone_destroy(struct ifnet *ifp)
 	/* Undo pseudo-driver changes. */
 	if_deactivate(ifp);
 
-	bridge_ifih = SLIST_FIRST(&ifp->if_inputs);
-	SLIST_REMOVE_HEAD(&ifp->if_inputs, ifih_next);
-
-	KASSERT(SLIST_EMPTY(&ifp->if_inputs));
+	if_ih_remove(ifp, ether_input);
 
-	free(bridge_ifih, M_DEVBUF, sizeof(*bridge_ifih));
+	KASSERT(SRPL_EMPTY_LOCKED(&ifp->if_inputs));
 
 	if_detach(ifp);
 
diff --git a/sys/net/if_ethersubr.c b/sys/net/if_ethersubr.c
index f7845beeb80..eee6da9a2af 100644
--- a/sys/net/if_ethersubr.c
+++ b/sys/net/if_ethersubr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_ethersubr.c,v 1.221 2015/07/29 00:04:03 rzalamena Exp $	*/
+/*	$OpenBSD: if_ethersubr.c,v 1.222 2015/09/10 13:32:19 dlg Exp $	*/
 /*	$NetBSD: if_ethersubr.c,v 1.19 1996/05/07 02:40:30 thorpej Exp $	*/
 
 /*
@@ -492,7 +492,6 @@ void
 ether_ifattach(struct ifnet *ifp)
 {
 	struct arpcom *ac = (struct arpcom *)ifp;
-	struct ifih *ether_ifih;
 
 	/*
 	 * Any interface which provides a MAC address which is obviously
@@ -507,9 +506,7 @@ ether_ifattach(struct ifnet *ifp)
 	ifp->if_mtu = ETHERMTU;
 	ifp->if_output = ether_output;
 
-	ether_ifih = malloc(sizeof(*ether_ifih), M_DEVBUF, M_WAITOK);
-	ether_ifih->ifih_input = ether_input;
-	SLIST_INSERT_HEAD(&ifp->if_inputs, ether_ifih, ifih_next);
+	if_ih_insert(ifp, ether_input);
 
 	if (ifp->if_hardmtu == 0)
 		ifp->if_hardmtu = ETHERMTU;
@@ -526,18 +523,14 @@ void
 ether_ifdetach(struct ifnet *ifp)
 {
 	struct arpcom *ac = (struct arpcom *)ifp;
-	struct ifih *ether_ifih;
 	struct ether_multi *enm;
 
 	/* Undo pseudo-driver changes. */
 	if_deactivate(ifp);
 
-	ether_ifih = SLIST_FIRST(&ifp->if_inputs);
-	SLIST_REMOVE_HEAD(&ifp->if_inputs, ifih_next);
+	if_ih_remove(ifp, ether_input);
 
-	KASSERT(SLIST_EMPTY(&ifp->if_inputs));
-
-	free(ether_ifih, M_DEVBUF, sizeof(*ether_ifih));
+	KASSERT(SRPL_EMPTY_LOCKED(&ifp->if_inputs));
 
 	for (enm = LIST_FIRST(&ac->ac_multiaddrs);
 	    enm != NULL;
diff --git a/sys/net/if_mpw.c b/sys/net/if_mpw.c
index c92a3f90eff..b6fe8e6b9cc 100644
--- a/sys/net/if_mpw.c
+++ b/sys/net/if_mpw.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_mpw.c,v 1.3 2015/09/09 20:13:20 dlg Exp $ */
+/*	$OpenBSD: if_mpw.c,v 1.4 2015/09/10 13:32:19 dlg Exp $ */
 
 /*
  * Copyright (c) 2015 Rafael Zalamena <rzalamena@openbsd.org>
@@ -82,18 +82,11 @@ mpw_clone_create(struct if_clone *ifc, int unit)
 {
 	struct mpw_softc *sc;
 	struct ifnet *ifp;
-	struct ifih *ifih;
 
 	sc = malloc(sizeof(*sc), M_DEVBUF, M_NOWAIT | M_ZERO);
 	if (sc == NULL)
 		return (ENOMEM);
 
-	ifih = malloc(sizeof(*ifih), M_DEVBUF, M_NOWAIT | M_ZERO);
-	if (ifih == NULL) {
-		free(sc, M_DEVBUF, sizeof(*sc));
-		return (ENOMEM);
-	}
-
 	ifp = &sc->sc_if;
 	snprintf(ifp->if_xname, sizeof(ifp->if_xname), "mpw%d", unit);
 	ifp->if_softc = sc;
@@ -116,8 +109,7 @@ mpw_clone_create(struct if_clone *ifc, int unit)
 	sc->sc_smpls.smpls_len = sizeof(sc->sc_smpls);
 	sc->sc_smpls.smpls_family = AF_MPLS;
 
-	ifih->ifih_input = mpw_input;
-	SLIST_INSERT_HEAD(&ifp->if_inputs, ifih, ifih_next);
+	if_ih_insert(ifp, mpw_input);
 
 #if NBPFILTER > 0
 	bpfattach(&ifp->if_bpf, ifp, DLT_EN10MB, ETHER_HDR_LEN);
@@ -130,7 +122,6 @@ int
 mpw_clone_destroy(struct ifnet *ifp)
 {
 	struct mpw_softc *sc = ifp->if_softc;
-	struct ifih *ifih = SLIST_FIRST(&ifp->if_inputs);
 	int s;
 
 	ifp->if_flags &= ~IFF_RUNNING;
@@ -142,8 +133,7 @@ mpw_clone_destroy(struct ifnet *ifp)
 		splx(s);
 	}
 
-	SLIST_REMOVE(&ifp->if_inputs, ifih, ifih, ifih_next);
-	free(ifih, M_DEVBUF, sizeof(*ifih));
+	if_ih_remove(ifp, mpw_input);
 
 	if_detach(ifp);
 	free(sc, M_DEVBUF, sizeof(*sc));
diff --git a/sys/net/if_trunk.c b/sys/net/if_trunk.c
index f51d2c0d261..b55843328d8 100644
--- a/sys/net/if_trunk.c
+++ b/sys/net/if_trunk.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_trunk.c,v 1.109 2015/07/17 23:32:18 mpi Exp $	*/
+/*	$OpenBSD: if_trunk.c,v 1.110 2015/09/10 13:32:19 dlg Exp $	*/
 
 /*
  * Copyright (c) 2005, 2006, 2007 Reyk Floeter <reyk@openbsd.org>
@@ -344,8 +344,7 @@ trunk_port_create(struct trunk_softc *tr, struct ifnet *ifp)
 	ifp->if_type = IFT_IEEE8023ADLAG;
 
 	/* Change input handler of the physical interface. */
-	tp->tp_ifih.ifih_input = trunk_input;
-	SLIST_INSERT_HEAD(&ifp->if_inputs, &tp->tp_ifih, ifih_next);
+	if_ih_insert(ifp, trunk_input);
 
 	ifp->if_tp = (caddr_t)tp;
 	tp->tp_ioctl = ifp->if_ioctl;
@@ -438,7 +437,7 @@ trunk_port_destroy(struct trunk_port *tp)
 	ifp->if_type = tp->tp_iftype;
 
 	/* Restore previous input handler. */
-	SLIST_REMOVE(&ifp->if_inputs, &tp->tp_ifih, ifih, ifih_next);
+	if_ih_remove(ifp, trunk_input);
 
 	ifp->if_watchdog = tp->tp_watchdog;
 	ifp->if_ioctl = tp->tp_ioctl;
diff --git a/sys/net/if_trunk.h b/sys/net/if_trunk.h
index a5d1dea7774..e4eaffbd5da 100644
--- a/sys/net/if_trunk.h
+++ b/sys/net/if_trunk.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_trunk.h,v 1.23 2015/05/26 11:39:07 mpi Exp $	*/
+/*	$OpenBSD: if_trunk.h,v 1.24 2015/09/10 13:32:19 dlg Exp $	*/
 
 /*
  * Copyright (c) 2005, 2006, 2007 Reyk Floeter <reyk@openbsd.org>
@@ -137,7 +137,6 @@ struct trunk_port {
 	u_int32_t			tp_flags;	/* port flags */
 	void				*lh_cookie;	/* if state hook */
 	void				*dh_cookie;	/* if detach hook */
-	struct ifih			tp_ifih;	/* input handler */
 
 	/* Redirected callbacks */
 	void	(*tp_watchdog)(struct ifnet *);
diff --git a/sys/net/if_var.h b/sys/net/if_var.h
index ba57aa11514..69e6c2e9a21 100644
--- a/sys/net/if_var.h
+++ b/sys/net/if_var.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_var.h,v 1.35 2015/09/09 16:01:10 dlg Exp $	*/
+/*	$OpenBSD: if_var.h,v 1.36 2015/09/10 13:32:19 dlg Exp $	*/
 /*	$NetBSD: if.h,v 1.23 1996/05/07 02:40:27 thorpej Exp $	*/
 
 /*
@@ -110,15 +110,6 @@ struct	ifqueue {
 };
 
 /*
- * Interface input hooks.
- */
-struct ifih {
-	SLIST_ENTRY(ifih) ifih_next;
-	int		(*ifih_input)(struct ifnet *, struct mbuf *);
-	int		  ifih_refcnt;
-};
-
-/*
  * Structure defining a queue for a network interface.
  *
  * (Would like to call this struct ``if'', but C isn't PL/1.)
@@ -161,7 +152,7 @@ struct ifnet {				/* and the entries */
 	struct	task *if_linkstatetask; /* task to do route updates */
 
 	/* procedure handles */
-	SLIST_HEAD(, ifih) if_inputs;	/* input routines (dequeue) */
+	struct	srpl if_inputs;		/* input routines (dequeue) */
 
 					/* output routine (enqueue) */
 	int	(*if_output)(struct ifnet *, struct mbuf *, struct sockaddr *,
@@ -449,6 +440,9 @@ void	ifa_del(struct ifnet *, struct ifaddr *);
 void	ifa_update_broadaddr(struct ifnet *, struct ifaddr *,
 	    struct sockaddr *);
 
+void	if_ih_insert(struct ifnet *, int (*)(struct ifnet *, struct mbuf *));
+void	if_ih_remove(struct ifnet *, int (*)(struct ifnet *, struct mbuf *));
+
 void	if_rxr_init(struct if_rxring *, u_int, u_int);
 u_int	if_rxr_get(struct if_rxring *, u_int);
 
diff --git a/sys/net/if_vlan.c b/sys/net/if_vlan.c
index 633c5d9ea07..4329bf0c0f6 100644
--- a/sys/net/if_vlan.c
+++ b/sys/net/if_vlan.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_vlan.c,v 1.135 2015/07/20 22:16:41 rzalamena Exp $	*/
+/*	$OpenBSD: if_vlan.c,v 1.136 2015/09/10 13:32:19 dlg Exp $	*/
 
 /*
  * Copyright 1998 Massachusetts Institute of Technology
@@ -357,17 +357,6 @@ vlan_config(struct ifvlan *ifv, struct ifnet *p, u_int16_t tag)
 	if (ifv->ifv_p == p && ifv->ifv_tag == tag) /* noop */
 		return (0);
 
-	/* Can we share an ifih between multiple vlan(4) instances? */
-	ifv->ifv_ifih = SLIST_FIRST(&p->if_inputs);
-	if (ifv->ifv_ifih->ifih_input != vlan_input) {
-		ifv->ifv_ifih = malloc(sizeof(*ifv->ifv_ifih), M_DEVBUF,
-		    M_NOWAIT);
-		if (ifv->ifv_ifih == NULL)
-			return (ENOMEM);
-		ifv->ifv_ifih->ifih_input = vlan_input;
-		ifv->ifv_ifih->ifih_refcnt = 0;
-	}
-
 	/* Remember existing interface flags and reset the interface */
 	flags = ifv->ifv_flags;
 	vlan_unconfig(&ifv->ifv_if, p);
@@ -436,13 +425,12 @@ vlan_config(struct ifvlan *ifv, struct ifnet *p, u_int16_t tag)
 	tagh = ifv->ifv_type == ETHERTYPE_QINQ ? svlan_tagh : vlan_tagh;
 
 	s = splnet();
-	/* Change input handler of the physical interface. */
-	if (++ifv->ifv_ifih->ifih_refcnt == 1)
-		SLIST_INSERT_HEAD(&p->if_inputs, ifv->ifv_ifih, ifih_next);
-
 	LIST_INSERT_HEAD(&tagh[TAG_HASH(tag)], ifv, ifv_list);
 	splx(s);
 
+        /* Change input handler of the physical interface. */
+	if_ih_insert(p, vlan_input);
+
 	return (0);
 }
 
@@ -466,13 +454,10 @@ vlan_unconfig(struct ifnet *ifp, struct ifnet *newp)
 
 	s = splnet();
 	LIST_REMOVE(ifv, ifv_list);
-
-	/* Restore previous input handler. */
-	if (--ifv->ifv_ifih->ifih_refcnt == 0) {
-		SLIST_REMOVE(&p->if_inputs, ifv->ifv_ifih, ifih, ifih_next);
-		free(ifv->ifv_ifih, M_DEVBUF, sizeof(*ifv->ifv_ifih));
-	}
 	splx(s);
+ 
+	/* Restore previous input handler. */
+	if_ih_remove(p, vlan_input);
 
 	hook_disestablish(p->if_linkstatehooks, ifv->lh_cookie);
 	hook_disestablish(p->if_detachhooks, ifv->dh_cookie);