Commit 66cddf10 authored by Julian Wiedmann's avatar Julian Wiedmann Committed by David S. Miller
Browse files

s390/qeth: allow configuration of TX queues for IQD devices 



Similar to the support for z/VM NICs, but we need to take extra care
about the dedicated mcast queue:

1. netdev_pick_tx() is unaware of this limitation and might select the
   mcast txq. Catch this.
2. require at least _two_ TX queues - one for ucast, one for mcast.
3. when reducing the number of TX queues, there's a potential race
   where netdev_cap_txqueue() over-rules the selected txq index and
   falls back to index 0. This would place ucast traffic on the mcast
   queue, and result in TX errors.
   So for IQD, reject a reduction while the interface is running.

Signed-off-by: default avatarJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent fcc2df8b

drivers/s390/net/qeth_core_main.c

+5 −1
Original line number Diff line number Diff line
@@ -6644,9 +6644,13 @@ EXPORT_SYMBOL_GPL(qeth_get_stats64); 
u16 qeth_iqd_select_queue(struct net_device *dev, struct sk_buff *skb,

			  u8 cast_type, struct net_device *sb_dev)

{

	u16 txq;



	if (cast_type != RTN_UNICAST)

		return QETH_IQD_MCAST_TXQ;

	return QETH_IQD_MIN_UCAST_TXQ;



	txq = netdev_pick_tx(dev, skb, sb_dev);

	return (txq == QETH_IQD_MCAST_TXQ) ? QETH_IQD_MIN_UCAST_TXQ : txq;

}

EXPORT_SYMBOL_GPL(qeth_iqd_select_queue);

drivers/s390/net/qeth_ethtool.c

+16 −3
Original line number Diff line number Diff line
@@ -180,14 +180,27 @@ static int qeth_set_channels(struct net_device *dev, 
{

	struct qeth_card *card = dev->ml_priv;



	if (IS_IQD(card) || !IS_VM_NIC(card))

		return -EOPNOTSUPP;



	if (channels->rx_count == 0 || channels->tx_count == 0)

		return -EINVAL;

	if (channels->tx_count > card->qdio.no_out_queues)

		return -EINVAL;



	if (IS_IQD(card)) {

		if (channels->tx_count < QETH_IQD_MIN_TXQ)

			return -EINVAL;



		/* Reject downgrade while running. It could push displaced

		 * ucast flows onto txq0, which is reserved for mcast.

		 */

		if (netif_running(dev) &&

		    channels->tx_count < dev->real_num_tx_queues)

			return -EPERM;

	} else {

		/* OSA still uses the legacy prio-queue mechanism: */

		if (!IS_VM_NIC(card))

			return -EOPNOTSUPP;

	}



	return netif_set_real_num_tx_queues(dev, channels->tx_count);

}

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