On Sun, Jan 02, 2011 at 09:46:16PM -0800, John Fastabend wrote:

On 12/31/2010 1:25 AM, Jarek Poplawski wrote:

quoted

On 2010-12-21 20:29, John Fastabend wrote:

quoted

+static int mclass_parse_opt(struct net_device *dev, struct tc_mclass_qopt *qopt)
+{
+	int i, j;
+
+	/* Verify TC offset and count are sane */

if (qopt->num_tc > TC_MAX_QUEUE) ?
	return -EINVAL;

This would be caught later when netdev_set_num_tc() fails although probably best to catch all failures in this function as early as possible.

Plus reading beyond the table range wouldn't look nice.

quoted

quoted

+	for (i = 0; i < qopt->num_tc; i++) {
+		int last = qopt->offset[i] + qopt->count[i];
+		if (last > dev->num_tx_queues)

if (last >= dev->num_tx_queues) ?

quoted

+			return -EINVAL;
+		for (j = i + 1; j < qopt->num_tc; j++) {
+			if (last > qopt->offset[j])

if (last >= qopt->offset[j]) ?

	
I believe the below works as expected. The offset needs to be verified (this I missed) but offset+count can be equal to num_tx_queue indicating the last queue is in use. With 8 tx queues and num_tc=2 a valid configuration is, tc1 offset of 0 and a count of 7 with tc2 offset of 7 and count of 1.


        /* Verify num_tc is in max range */
        if (qopt->num_tc > TC_MAX_QUEUE)
                return -EINVAL;

        for (i = 0; i < qopt->num_tc; i++) {
                /* Verify the queue offset is in the num tx range */
                if (qopt->offset[i] >= dev->num_tx_queues)
                        return -EINVAL;
                /* Verify the queue count is in tx range being equal to the
                 * num_tx_queues indicates the last queue is in use.
                 */
                else if (qopt->offset[i] + qopt->count[i] > dev->num_tx_queues)
                        return -EINVAL;

                /* Verify that the offset and counts do not overlap */
                for (j = i + 1; j < qopt->num_tc; j++) {
                        if (last > qopt->offset[j])
                                return -EINVAL;
                }
        }

Yes, after assigning the 'last' it should work OK ;-)

Thanks,
Jarek P.