From: Holger Schurig <h.schurig@mn-solutions.de>
To: linux-wireless <linux-wireless@vger.kernel.org>
Subject: Question regarding netif_stop/wake queue and libertas
Date: Wed, 7 Oct 2009 09:50:52 +0200
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Message-Id: <200910070950.52196.h.schurig@mn-solutions.de>
Sender: linux-wireless-owner@vger.kernel.org

Hi !

In the libertas driver, we did the following before scanning:

	netif_stop_queue(priv->dev);
	netif_carrier_off(priv->dev);
	if (priv->mesh_dev) {
		netif_stop_queue(priv->mesh_dev);
		netif_carrier_off(priv->mesh_dev);
	}

and then, after scanning, we started the queues and carrier
again *IF* connected:

	if (priv->connect_status == LBS_CONNECTED) {
		netif_carrier_on(priv->dev);
		if (!priv->tx_pending_len)
			netif_wake_queue(priv->dev);
	}
	if (priv->mesh_dev && (priv->mesh_connect_status == LBS_CONNECTED)) {
		netif_carrier_on(priv->mesh_dev);
		if (!priv->tx_pending_len)
			netif_wake_queue(priv->mesh_dev);
	}

How should I do this in my CFG80211-based scanning? As I want
to move away from libertas' own association logic in assoc.c,
there will in future be no priv->connect_status.

I now plan to remember the running/carrier state of both the
"normal" and the "mesh" device:

	int running;
	int carrier;
	int mesh_running = false;
	int mesh_carrier = false;

	running = !netif_queue_stopped(priv->dev);
	carrier = netif_carrier_ok(priv->dev);
	if (running)
		netif_stop_queue(priv->dev);
	if (carrier)
		netif_carrier_off(priv->dev);
	if (priv->mesh_dev) {
		mesh_running = !netif_queue_stopped(priv->mesh_dev);
		mesh_carrier = netif_carrier_ok(priv->mesh_dev);
		if (mesh_running)
			netif_stop_queue(priv->mesh_dev);
		if (mesh_carrier)
			netif_carrier_off(priv->mesh_dev);
	}

And after scanning my four channels, I plan to turn them
on again (e.g. this can be 440 ms later when doing a passive
scan):

	if (carrier)
		netif_carrier_on(priv->dev);
	if (running && !priv->tx_pending_len)
		netif_wake_queue(priv->dev);
	if (mesh_carrier)
		netif_carrier_on(priv->mesh_dev);
	if (mesh_running %% !priv->tx_pending_len)
		netif_wake_queue(priv->mesh_dev)

Would I need some kind of locking ?

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