mac802154: Keep track of the channel when changed

Two sections checked whether the current channel != the new channel
without ever setting the current channel variables.

1. net/mac802154/tx.c: Prevent set_channel() from getting called every
time a packet is sent.

2. net/mac802154/mib.c: Lock (pib_lock) accesses to current_channel and
current_page and make sure they are updated when the channel has been
changed.

Signed-off-by: Alan Ott <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/mac802154/mib.c

···
 	struct mac802154_sub_if_data *priv = netdev_priv(nw->dev);
 	int res;
 
+	mutex_lock(&priv->hw->phy->pib_lock);
 	res = hw->ops->set_channel(&hw->hw, priv->page, priv->chan);
 	if (res)
 		pr_debug("set_channel failed\n");
+	else {
+		priv->hw->phy->current_channel = priv->chan;
+		priv->hw->phy->current_page = priv->page;
+	}
+	mutex_unlock(&priv->hw->phy->pib_lock);
 
 	kfree(nw);
 }
···
 	priv->chan = chan;
 	spin_unlock_bh(&priv->mib_lock);
 
+	mutex_lock(&priv->hw->phy->pib_lock);
 	if (priv->hw->phy->current_channel != priv->chan ||
 	    priv->hw->phy->current_page != priv->page) {
+		mutex_unlock(&priv->hw->phy->pib_lock);
+
 		work = kzalloc(sizeof(*work), GFP_ATOMIC);
 		if (!work)
 			return;
···
 		INIT_WORK(&work->work, phy_chan_notify);
 		work->dev = dev;
 		queue_work(priv->hw->dev_workqueue, &work->work);
-	}
+	} else
+		mutex_unlock(&priv->hw->phy->pib_lock);
 }

net/mac802154/tx.c

···
 			pr_debug("set_channel failed\n");
 			goto out;
 		}
+
+		xw->priv->phy->current_channel = xw->chan;
+		xw->priv->phy->current_page = xw->page;
 	}
 
 	res = xw->priv->ops->xmit(&xw->priv->hw, xw->skb);