bridge: vlan: use proper rcu for the vlgrp member

The bridge and port's vlgrp member is already used in RCU way, currently
we rely on the fact that it cannot disappear while the port exists but
that is error-prone and we might miss places with improper locking
(either RCU or RTNL must be held to walk the vlan_list). So make it
official and use RCU for vlgrp to catch offenders. Introduce proper vlgrp
accessors and use them consistently throughout the code.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 66 insertions, 41 deletions

diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
index ad7e4f6b6d6b..ffaa6d986505 100644
--- a/net/bridge/br_vlan.c
+++ b/net/bridge/br_vlan.c
@@ -54,9 +54,9 @@ static void __vlan_add_flags(struct net_bridge_vlan *v, u16 flags)
 	struct net_bridge_vlan_group *vg;
 
 	if (br_vlan_is_master(v))
-		vg = v->br->vlgrp;
+		vg = br_vlan_group(v->br);
 	else
-		vg = v->port->vlgrp;
+		vg = nbp_vlan_group(v->port);
 
 	if (flags & BRIDGE_VLAN_INFO_PVID)
 		__vlan_add_pvid(vg, v->vid);
@@ -91,11 +91,16 @@ static int __vlan_vid_add(struct net_device *dev, struct net_bridge *br,
 
 static void __vlan_add_list(struct net_bridge_vlan *v)
 {
+	struct net_bridge_vlan_group *vg;
 	struct list_head *headp, *hpos;
 	struct net_bridge_vlan *vent;
 
-	headp = br_vlan_is_master(v) ? &v->br->vlgrp->vlan_list :
-				       &v->port->vlgrp->vlan_list;
+	if (br_vlan_is_master(v))
+		vg = br_vlan_group(v->br);
+	else
+		vg = nbp_vlan_group(v->port);
+
+	headp = &vg->vlan_list;
 	list_for_each_prev(hpos, headp) {
 		vent = list_entry(hpos, struct net_bridge_vlan, vlist);
 		if (v->vid < vent->vid)
@@ -137,14 +142,16 @@ static int __vlan_vid_del(struct net_device *dev, struct net_bridge *br,
  */
 static struct net_bridge_vlan *br_vlan_get_master(struct net_bridge *br, u16 vid)
 {
+	struct net_bridge_vlan_group *vg;
 	struct net_bridge_vlan *masterv;
 
-	masterv = br_vlan_find(br->vlgrp, vid);
+	vg = br_vlan_group(br);
+	masterv = br_vlan_find(vg, vid);
 	if (!masterv) {
 		/* missing global ctx, create it now */
 		if (br_vlan_add(br, vid, 0))
 			return NULL;
-		masterv = br_vlan_find(br->vlgrp, vid);
+		masterv = br_vlan_find(vg, vid);
 		if (WARN_ON(!masterv))
 			return NULL;
 	}
@@ -155,11 +162,14 @@ static struct net_bridge_vlan *br_vlan_get_master(struct net_bridge *br, u16 vid
 
 static void br_vlan_put_master(struct net_bridge_vlan *masterv)
 {
+	struct net_bridge_vlan_group *vg;
+
 	if (!br_vlan_is_master(masterv))
 		return;
 
+	vg = br_vlan_group(masterv->br);
 	if (atomic_dec_and_test(&masterv->refcnt)) {
-		rhashtable_remove_fast(&masterv->br->vlgrp->vlan_hash,
+		rhashtable_remove_fast(&vg->vlan_hash,
 				       &masterv->vnode, br_vlan_rht_params);
 		__vlan_del_list(masterv);
 		kfree_rcu(masterv, rcu);
@@ -189,12 +199,12 @@ static int __vlan_add(struct net_bridge_vlan *v, u16 flags)
 	if (br_vlan_is_master(v)) {
 		br = v->br;
 		dev = br->dev;
-		vg = br->vlgrp;
+		vg = br_vlan_group(br);
 	} else {
 		p = v->port;
 		br = p->br;
 		dev = p->dev;
-		vg = p->vlgrp;
+		vg = nbp_vlan_group(p);
 	}
 
 	if (p) {
@@ -266,10 +276,10 @@ static int __vlan_del(struct net_bridge_vlan *v)
 	int err = 0;
 
 	if (br_vlan_is_master(v)) {
-		vg = v->br->vlgrp;
+		vg = br_vlan_group(v->br);
 	} else {
 		p = v->port;
-		vg = v->port->vlgrp;
+		vg = nbp_vlan_group(v->port);
 		masterv = v->brvlan;
 	}
 
@@ -305,7 +315,7 @@ static void __vlan_flush(struct net_bridge_vlan_group *vlgrp)
 	list_for_each_entry_safe(vlan, tmp, &vlgrp->vlan_list, vlist)
 		__vlan_del(vlan);
 	rhashtable_destroy(&vlgrp->vlan_hash);
-	kfree(vlgrp);
+	kfree_rcu(vlgrp, rcu);
 }
 
 struct sk_buff *br_handle_vlan(struct net_bridge *br,
@@ -467,7 +477,7 @@ bool br_should_learn(struct net_bridge_port *p, struct sk_buff *skb, u16 *vid)
 	if (!br->vlan_enabled)
 		return true;
 
-	vg = p->vlgrp;
+	vg = nbp_vlan_group(p);
 	if (!vg || !vg->num_vlans)
 		return false;
 
@@ -493,12 +503,14 @@ bool br_should_learn(struct net_bridge_port *p, struct sk_buff *skb, u16 *vid)
  */
 int br_vlan_add(struct net_bridge *br, u16 vid, u16 flags)
 {
+	struct net_bridge_vlan_group *vg;
 	struct net_bridge_vlan *vlan;
 	int ret;
 
 	ASSERT_RTNL();
 
-	vlan = br_vlan_find(br->vlgrp, vid);
+	vg = br_vlan_group(br);
+	vlan = br_vlan_find(vg, vid);
 	if (vlan) {
 		if (!br_vlan_is_brentry(vlan)) {
 			/* Trying to change flags of non-existent bridge vlan */
@@ -513,7 +525,7 @@ int br_vlan_add(struct net_bridge *br, u16 vid, u16 flags)
 			}
 			atomic_inc(&vlan->refcnt);
 			vlan->flags |= BRIDGE_VLAN_INFO_BRENTRY;
-			br->vlgrp->num_vlans++;
+			vg->num_vlans++;
 		}
 		__vlan_add_flags(vlan, flags);
 		return 0;
@@ -541,11 +553,13 @@ int br_vlan_add(struct net_bridge *br, u16 vid, u16 flags)
  */
 int br_vlan_delete(struct net_bridge *br, u16 vid)
 {
+	struct net_bridge_vlan_group *vg;
 	struct net_bridge_vlan *v;
 
 	ASSERT_RTNL();
 
-	v = br_vlan_find(br->vlgrp, vid);
+	vg = br_vlan_group(br);
+	v = br_vlan_find(vg, vid);
 	if (!v || !br_vlan_is_brentry(v))
 		return -ENOENT;
 
@@ -626,6 +640,7 @@ int __br_vlan_set_proto(struct net_bridge *br, __be16 proto)
 	int err = 0;
 	struct net_bridge_port *p;
 	struct net_bridge_vlan *vlan;
+	struct net_bridge_vlan_group *vg;
 	__be16 oldproto;
 
 	if (br->vlan_proto == proto)
@@ -633,7 +648,8 @@ int __br_vlan_set_proto(struct net_bridge *br, __be16 proto)
 
 	/* Add VLANs for the new proto to the device filter. */
 	list_for_each_entry(p, &br->port_list, list) {
-		list_for_each_entry(vlan, &p->vlgrp->vlan_list, vlist) {
+		vg = nbp_vlan_group(p);
+		list_for_each_entry(vlan, &vg->vlan_list, vlist) {
 			err = vlan_vid_add(p->dev, proto, vlan->vid);
 			if (err)
 				goto err_filt;
@@ -647,19 +663,23 @@ int __br_vlan_set_proto(struct net_bridge *br, __be16 proto)
 	br_recalculate_fwd_mask(br);
 
 	/* Delete VLANs for the old proto from the device filter. */
-	list_for_each_entry(p, &br->port_list, list)
-		list_for_each_entry(vlan, &p->vlgrp->vlan_list, vlist)
+	list_for_each_entry(p, &br->port_list, list) {
+		vg = nbp_vlan_group(p);
+		list_for_each_entry(vlan, &vg->vlan_list, vlist)
 			vlan_vid_del(p->dev, oldproto, vlan->vid);
+	}
 
 	return 0;
 
 err_filt:
-	list_for_each_entry_continue_reverse(vlan, &p->vlgrp->vlan_list, vlist)
+	list_for_each_entry_continue_reverse(vlan, &vg->vlan_list, vlist)
 		vlan_vid_del(p->dev, proto, vlan->vid);
 
-	list_for_each_entry_continue_reverse(p, &br->port_list, list)
-		list_for_each_entry(vlan, &p->vlgrp->vlan_list, vlist)
+	list_for_each_entry_continue_reverse(p, &br->port_list, list) {
+		vg = nbp_vlan_group(p);
+		list_for_each_entry(vlan, &vg->vlan_list, vlist)
 			vlan_vid_del(p->dev, proto, vlan->vid);
+	}
 
 	return err;
 }
@@ -703,11 +723,11 @@ static void br_vlan_disable_default_pvid(struct net_bridge *br)
 	/* Disable default_pvid on all ports where it is still
 	 * configured.
 	 */
-	if (vlan_default_pvid(br->vlgrp, pvid))
+	if (vlan_default_pvid(br_vlan_group(br), pvid))
 		br_vlan_delete(br, pvid);
 
 	list_for_each_entry(p, &br->port_list, list) {
-		if (vlan_default_pvid(p->vlgrp, pvid))
+		if (vlan_default_pvid(nbp_vlan_group(p), pvid))
 			nbp_vlan_delete(p, pvid);
 	}
 
@@ -717,6 +737,7 @@ static void br_vlan_disable_default_pvid(struct net_bridge *br)
 int __br_vlan_set_default_pvid(struct net_bridge *br, u16 pvid)
 {
 	const struct net_bridge_vlan *pvent;
+	struct net_bridge_vlan_group *vg;
 	struct net_bridge_port *p;
 	u16 old_pvid;
 	int err = 0;
@@ -737,8 +758,9 @@ int __br_vlan_set_default_pvid(struct net_bridge *br, u16 pvid)
 	/* Update default_pvid config only if we do not conflict with
 	 * user configuration.
 	 */
-	pvent = br_vlan_find(br->vlgrp, pvid);
-	if ((!old_pvid || vlan_default_pvid(br->vlgrp, old_pvid)) &&
+	vg = br_vlan_group(br);
+	pvent = br_vlan_find(vg, pvid);
+	if ((!old_pvid || vlan_default_pvid(vg, old_pvid)) &&
 	    (!pvent || !br_vlan_should_use(pvent))) {
 		err = br_vlan_add(br, pvid,
 				  BRIDGE_VLAN_INFO_PVID |
@@ -754,9 +776,10 @@ int __br_vlan_set_default_pvid(struct net_bridge *br, u16 pvid)
 		/* Update default_pvid config only if we do not conflict with
 		 * user configuration.
 		 */
+		vg = nbp_vlan_group(p);
 		if ((old_pvid &&
-		     !vlan_default_pvid(p->vlgrp, old_pvid)) ||
-		    br_vlan_find(p->vlgrp, pvid))
+		     !vlan_default_pvid(vg, old_pvid)) ||
+		    br_vlan_find(vg, pvid))
 			continue;
 
 		err = nbp_vlan_add(p, pvid,
@@ -825,17 +848,19 @@ unlock:
 
 int br_vlan_init(struct net_bridge *br)
 {
+	struct net_bridge_vlan_group *vg;
 	int ret = -ENOMEM;
 
-	br->vlgrp = kzalloc(sizeof(struct net_bridge_vlan_group), GFP_KERNEL);
-	if (!br->vlgrp)
+	vg = kzalloc(sizeof(*vg), GFP_KERNEL);
+	if (!vg)
 		goto out;
-	ret = rhashtable_init(&br->vlgrp->vlan_hash, &br_vlan_rht_params);
+	ret = rhashtable_init(&vg->vlan_hash, &br_vlan_rht_params);
 	if (ret)
 		goto err_rhtbl;
-	INIT_LIST_HEAD(&br->vlgrp->vlan_list);
+	INIT_LIST_HEAD(&vg->vlan_list);
 	br->vlan_proto = htons(ETH_P_8021Q);
 	br->default_pvid = 1;
+	rcu_assign_pointer(br->vlgrp, vg);
 	ret = br_vlan_add(br, 1,
 			  BRIDGE_VLAN_INFO_PVID | BRIDGE_VLAN_INFO_UNTAGGED |
 			  BRIDGE_VLAN_INFO_BRENTRY);
@@ -846,9 +871,9 @@ out:
 	return ret;
 
 err_vlan_add:
-	rhashtable_destroy(&br->vlgrp->vlan_hash);
+	rhashtable_destroy(&vg->vlan_hash);
 err_rhtbl:
-	kfree(br->vlgrp);
+	kfree(vg);
 
 	goto out;
 }
@@ -866,9 +891,7 @@ int nbp_vlan_init(struct net_bridge_port *p)
 	if (ret)
 		goto err_rhtbl;
 	INIT_LIST_HEAD(&vg->vlan_list);
-	/* Make sure everything's committed before publishing vg */
-	smp_wmb();
-	p->vlgrp = vg;
+	rcu_assign_pointer(p->vlgrp, vg);
 	if (p->br->default_pvid) {
 		ret = nbp_vlan_add(p, p->br->default_pvid,
 				   BRIDGE_VLAN_INFO_PVID |
@@ -897,7 +920,7 @@ int nbp_vlan_add(struct net_bridge_port *port, u16 vid, u16 flags)
 
 	ASSERT_RTNL();
 
-	vlan = br_vlan_find(port->vlgrp, vid);
+	vlan = br_vlan_find(nbp_vlan_group(port), vid);
 	if (vlan) {
 		__vlan_add_flags(vlan, flags);
 		return 0;
@@ -925,7 +948,7 @@ int nbp_vlan_delete(struct net_bridge_port *port, u16 vid)
 
 	ASSERT_RTNL();
 
-	v = br_vlan_find(port->vlgrp, vid);
+	v = br_vlan_find(nbp_vlan_group(port), vid);
 	if (!v)
 		return -ENOENT;
 	br_fdb_find_delete_local(port->br, port, port->dev->dev_addr, vid);
@@ -936,12 +959,14 @@ int nbp_vlan_delete(struct net_bridge_port *port, u16 vid)
 
 void nbp_vlan_flush(struct net_bridge_port *port)
 {
+	struct net_bridge_vlan_group *vg;
 	struct net_bridge_vlan *vlan;
 
 	ASSERT_RTNL();
 
-	list_for_each_entry(vlan, &port->vlgrp->vlan_list, vlist)
+	vg = nbp_vlan_group(port);
+	list_for_each_entry(vlan, &vg->vlan_list, vlist)
 		vlan_vid_del(port->dev, port->br->vlan_proto, vlan->vid);
 
-	__vlan_flush(nbp_vlan_group(port));
+	__vlan_flush(vg);
 }