net: mac802154: Introduce a synchronous API for MLME commands

This is the slow path, we need to wait for each command to be processed
before continuing so let's introduce an helper which does the
transmission and blocks until it gets notified of its asynchronous
completion. This helper is going to be used when introducing scan
support.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20220519150516.443078-10-miquel.raynal@bootlin.com
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>

net/mac802154/ieee802154_i.h

@@ -125,6 +125,10 @@ extern struct ieee802154_mlme_ops mac802154_mlme_wpan;
 void ieee802154_rx(struct ieee802154_local *local, struct sk_buff *skb);
 void ieee802154_xmit_sync_worker(struct work_struct *work);
 int ieee802154_sync_and_hold_queue(struct ieee802154_local *local);
+int ieee802154_mlme_op_pre(struct ieee802154_local *local);
+int ieee802154_mlme_tx(struct ieee802154_local *local, struct sk_buff *skb);
+void ieee802154_mlme_op_post(struct ieee802154_local *local);
+int ieee802154_mlme_tx_one(struct ieee802154_local *local, struct sk_buff *skb);
 netdev_tx_t
 ieee802154_monitor_start_xmit(struct sk_buff *skb, struct net_device *dev);
 netdev_tx_t

net/mac802154/tx.c

@@ -128,6 +128,50 @@ int ieee802154_sync_and_hold_queue(struct ieee802154_local *local)
 	return ieee802154_sync_queue(local);
 }
 
+int ieee802154_mlme_op_pre(struct ieee802154_local *local)
+{
+	return ieee802154_sync_and_hold_queue(local);
+}
+
+int ieee802154_mlme_tx(struct ieee802154_local *local, struct sk_buff *skb)
+{
+	int ret;
+
+	/* Avoid possible calls to ->ndo_stop() when we asynchronously perform
+	 * MLME transmissions.
+	 */
+	rtnl_lock();
+
+	/* Ensure the device was not stopped, otherwise error out */
+	if (!local->open_count) {
+		rtnl_unlock();
+		return -ENETDOWN;
+	}
+
+	ieee802154_tx(local, skb);
+	ret = ieee802154_sync_queue(local);
+
+	rtnl_unlock();
+
+	return ret;
+}
+
+void ieee802154_mlme_op_post(struct ieee802154_local *local)
+{
+	ieee802154_release_queue(local);
+}
+
+int ieee802154_mlme_tx_one(struct ieee802154_local *local, struct sk_buff *skb)
+{
+	int ret;
+
+	ieee802154_mlme_op_pre(local);
+	ret = ieee802154_mlme_tx(local, skb);
+	ieee802154_mlme_op_post(local);
+
+	return ret;
+}
+
 static netdev_tx_t
 ieee802154_hot_tx(struct ieee802154_local *local, struct sk_buff *skb)
 {