Re: [PATCH 13/39]: pkt_sched: Add qdisc_all_tx_empty()

[Patrick McHardy <kaber@trash.net>]

David Miller wrote:
> As per comments, this isn't a foolproof implementation.  This is being
> added so that we can contain and isolate all the explicit ->tx_queue
> references in the tree.
> 
> +/* Are all TX queues of the device empty?  */
> +static inline bool qdisc_all_tx_empty(const struct net_device *dev)
> +{
> +	struct netdev_queue *txq = &dev->tx_queue;
> +
> +	/* XXX This is not correct but it is good enough for the
> +	 * XXX one place that wants this, IRDA.  If we wanted to
> +	 * XXX do this right, we'd need to add a qdisc op to
> +	 * XXX probe for the queue state.
> +	 */
> +	return skb_queue_empty(&txq->qdisc->q);
> +}


It this comment referring to the fact that its looking at
qdisc->q itself, while the qdisc might be using internal
queues? If so, just using txq->qdisc->q.qlen should be
fine since qdiscs are required to always update this value,
even if they're not using the queue itself.