nl80211: Emit a SET_INTERFACE on iftype change

Let userspace learn about iftype changes by sending a notification
when handling the NL80211_CMD_SET_INTERFACE command.  There seems
to be no other place where the iftype can change: nl80211_set_interface
is the only caller of cfg80211_change_iface which is the only caller of
ops->change_virtual_intf.
Signed-off-by: Andrew Zaborowski <andrew.zaborowski@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -2977,14 +2977,15 @@ static int nl80211_send_chandef(struct sk_buff *msg,
 
 static int nl80211_send_iface(struct sk_buff *msg, u32 portid, u32 seq, int flags,
 			      struct cfg80211_registered_device *rdev,
-			      struct wireless_dev *wdev, bool removal)
+			      struct wireless_dev *wdev,
+			      enum nl80211_commands cmd)
 {
 	struct net_device *dev = wdev->netdev;
-	u8 cmd = NL80211_CMD_NEW_INTERFACE;
 	void *hdr;
 
-	if (removal)
-		cmd = NL80211_CMD_DEL_INTERFACE;
+	WARN_ON(cmd != NL80211_CMD_NEW_INTERFACE &&
+		cmd != NL80211_CMD_DEL_INTERFACE &&
+		cmd != NL80211_CMD_SET_INTERFACE);
 
 	hdr = nl80211hdr_put(msg, portid, seq, flags, cmd);
 	if (!hdr)
@@ -3132,7 +3133,8 @@ static int nl80211_dump_interface(struct sk_buff *skb, struct netlink_callback *
 			}
 			if (nl80211_send_iface(skb, NETLINK_CB(cb->skb).portid,
 					       cb->nlh->nlmsg_seq, NLM_F_MULTI,
-					       rdev, wdev, false) < 0) {
+					       rdev, wdev,
+					       NL80211_CMD_NEW_INTERFACE) < 0) {
 				goto out;
 			}
 			if_idx++;
@@ -3162,7 +3164,7 @@ static int nl80211_get_interface(struct sk_buff *skb, struct genl_info *info)
 		return -ENOMEM;
 
 	if (nl80211_send_iface(msg, info->snd_portid, info->snd_seq, 0,
-			       rdev, wdev, false) < 0) {
+			       rdev, wdev, NL80211_CMD_NEW_INTERFACE) < 0) {
 		nlmsg_free(msg);
 		return -ENOBUFS;
 	}
@@ -3352,6 +3354,12 @@ static int nl80211_set_interface(struct sk_buff *skb, struct genl_info *info)
 	if (!err && params.use_4addr != -1)
 		dev->ieee80211_ptr->use_4addr = params.use_4addr;
 
+	if (change && !err) {
+		struct wireless_dev *wdev = dev->ieee80211_ptr;
+
+		nl80211_notify_iface(rdev, wdev, NL80211_CMD_SET_INTERFACE);
+	}
+
 	return err;
 }
 
@@ -3443,7 +3451,7 @@ static int nl80211_new_interface(struct sk_buff *skb, struct genl_info *info)
 	}
 
 	if (nl80211_send_iface(msg, info->snd_portid, info->snd_seq, 0,
-			       rdev, wdev, false) < 0) {
+			       rdev, wdev, NL80211_CMD_NEW_INTERFACE) < 0) {
 		nlmsg_free(msg);
 		return -ENOBUFS;
 	}
@@ -14097,15 +14105,11 @@ void nl80211_notify_iface(struct cfg80211_registered_device *rdev,
 {
 	struct sk_buff *msg;
 
-	WARN_ON(cmd != NL80211_CMD_NEW_INTERFACE &&
-		cmd != NL80211_CMD_DEL_INTERFACE);
-
 	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 	if (!msg)
 		return;
 
-	if (nl80211_send_iface(msg, 0, 0, 0, rdev, wdev,
-			       cmd == NL80211_CMD_DEL_INTERFACE) < 0) {
+	if (nl80211_send_iface(msg, 0, 0, 0, rdev, wdev, cmd) < 0) {
 		nlmsg_free(msg);
 		return;
 	}