Re: [PATCH 1/2] mac802154: add a software MAC 802.15.4 implementation

On Mon, Aug 10, 2009 at 10:28:43AM -0700, Paul E. McKenney wrote:

On Mon, Aug 10, 2009 at 06:16:39PM +0400, Dmitry Eremin-Solenikov wrote:

quoted

Some of available devices are just dump radios implementing IEEE 802.15.4
PHY layer. This commit adds a common library that acts like an intermediate
layer between our socket family and drivers for those dumb devices.

Currently this is data-only part (no commands, no beacons). Control
interfaces will follow up shortly.

Note this implementaion is neither certified, nor feature complete!

One question below, otherwise looks plausible.  (I am not entirely sure
which lists are which...)

							Thanx, Paul

[skipped]

quoted

+
+/*
+ * This is for hw unregistration only, as it doesn't do RCU locking

So this list is different than the RCU-protected one, and readers
always hold locks when traversing it?

I am not familiar with this code, so might be missing something, but
it looks to me like the same list that RCU readers traverse.  If so,
need list_del_rcu() and synchronize_rcu().

On the first glance, yes. On the second glance, list_del instead of
list_del_rcu should be safe as there should be now other list traversals
at the same time. I'll think about it however.

quoted

+ */
+void ieee802154_drop_slaves(struct ieee802154_dev *hw)
+{
+	struct ieee802154_priv *priv = ieee802154_to_priv(hw);
+	struct ieee802154_sub_if_data *sdata, *next;
+
+	ASSERT_RTNL();
+
+	list_for_each_entry_safe(sdata, next, &priv->slaves, list) {
+		mutex_lock(&sdata->hw->slaves_mtx);
+		list_del(&sdata->list);
+		mutex_unlock(&sdata->hw->slaves_mtx);
+
+		dev_put(sdata->hw->netdev);
+
+		unregister_netdevice(sdata->dev);
+	}
+}

-- 
With best wishes
Dmitry


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