batman-adv: replace non-atomic vlan config fields with (READ|WRITE)_ONCE

The vlan configuration values are only accessed as plain loads/stores and
do not require full atomic_t semantics. Convert these fields to native
integer types and replace their users with READ_ONCE()/WRITE_ONCE() to
avoid load/store tearing.

Signed-off-by: Sven Eckelmann <sven@narfation.org>

Author: ecsv

net/batman-adv/main.c

@@ -627,7 +627,7 @@ bool batadv_vlan_ap_isola_get(struct batadv_priv *bat_priv, unsigned short vid)
 	 */
 	vlan = batadv_meshif_vlan_get(bat_priv, vid);
 	if (vlan) {
-		ap_isolation_enabled = atomic_read(&vlan->ap_isolation);
+		ap_isolation_enabled = READ_ONCE(vlan->ap_isolation);
 		batadv_meshif_vlan_put(vlan);
 	}
 

net/batman-adv/mesh-interface.c

@@ -567,7 +567,7 @@ int batadv_meshif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid)
 	vlan->vid = vid;
 	kref_init(&vlan->refcount);
 
-	atomic_set(&vlan->ap_isolation, 0);
+	WRITE_ONCE(vlan->ap_isolation, 0);
 
 	kref_get(&vlan->refcount);
 	hlist_add_head_rcu(&vlan->list, &bat_priv->meshif_vlan_list);

net/batman-adv/netlink.c

@@ -181,7 +181,7 @@ static int batadv_netlink_mesh_fill_ap_isolation(struct sk_buff *msg,
 	if (!vlan)
 		return 0;
 
-	ap_isolation = atomic_read(&vlan->ap_isolation);
+	ap_isolation = READ_ONCE(vlan->ap_isolation);
 	batadv_meshif_vlan_put(vlan);
 
 	return nla_put_u8(msg, BATADV_ATTR_AP_ISOLATION_ENABLED,
@@ -204,7 +204,7 @@ static int batadv_netlink_set_mesh_ap_isolation(struct nlattr *attr,
 	if (!vlan)
 		return -ENOENT;
 
-	atomic_set(&vlan->ap_isolation, !!nla_get_u8(attr));
+	WRITE_ONCE(vlan->ap_isolation, !!nla_get_u8(attr));
 	batadv_meshif_vlan_put(vlan);
 
 	return 0;
@@ -1022,7 +1022,7 @@ static int batadv_netlink_vlan_fill(struct sk_buff *msg,
 		goto nla_put_failure;
 
 	if (nla_put_u8(msg, BATADV_ATTR_AP_ISOLATION_ENABLED,
-		       !!atomic_read(&vlan->ap_isolation)))
+		       !!READ_ONCE(vlan->ap_isolation)))
 		goto nla_put_failure;
 
 	genlmsg_end(msg, hdr);
@@ -1110,7 +1110,7 @@ static int batadv_netlink_set_vlan(struct sk_buff *skb, struct genl_info *info)
 	if (info->attrs[BATADV_ATTR_AP_ISOLATION_ENABLED]) {
 		attr = info->attrs[BATADV_ATTR_AP_ISOLATION_ENABLED];
 
-		atomic_set(&vlan->ap_isolation, !!nla_get_u8(attr));
+		WRITE_ONCE(vlan->ap_isolation, !!nla_get_u8(attr));
 	}
 
 	batadv_netlink_notify_vlan(bat_priv, vlan);

net/batman-adv/translation-table.c

@@ -3730,7 +3730,7 @@ bool batadv_is_ap_isolated(struct batadv_priv *bat_priv, u8 *src, u8 *dst,
 	if (!vlan)
 		return false;
 
-	if (!atomic_read(&vlan->ap_isolation))
+	if (!READ_ONCE(vlan->ap_isolation))
 		goto vlan_put;
 
 	tt_local_entry = batadv_tt_local_hash_find(bat_priv, dst, vid);

net/batman-adv/types.h

@@ -1459,7 +1459,7 @@ struct batadv_meshif_vlan {
 	unsigned short vid;
 
 	/** @ap_isolation: AP isolation state */
-	atomic_t ap_isolation;		/* boolean */
+	u8 ap_isolation;		/* boolean */
 
 	/** @tt: TT private attributes (VLAN specific) */
 	struct batadv_vlan_tt tt;