On Fri, Jul 25, 2008 at 07:04:36PM +0200, Ingo Oeser wrote:
...

I'm sure as hell, I miss sth. but can't it be done by this pseudo-code:

...And I really doubt it can't be done like this.

Jarek P.

netif_tx_lock(device)
{
	mutex_lock(device->queue_entry_mutex);
	foreach_queue_entries(queue, device->queues)
	{
		spin_lock(queue->tx_lock);
		set_noop_tx_handler(queue);
		spin_unlock(queue->tx_lock);
	}
	mutex_unlock(device->queue_entry_mutex);
}

netif_tx_unlock(device)
{
	mutex_lock(device->queue_entry_mutex);
	foreach_queue_entries(queue, device->queues)
	{
		spin_lock(queue->tx_lock);
		set_useful_tx_handler(queue);
		spin_unlock(queue->tx_lock);
	}
	mutex_unlock(device->queue_entry_mutex);
}

Then protect use of the queues by queue->tx_lock in transmit path.
The first setup of the queue doesn't need to be protected, since no-one
knows the device. The final cleanup of the device doesn't need to be
protected either, because netif_tx_lock() and netif_tx_unlock() should
not be called after entering the final cleanup.

Some VM locking works this way...


Best Regards

Ingo Oeser

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