From 66cddf101901a6cfcd21c840f0535e8f1c8c5186 Mon Sep 17 00:00:00 2001 From: Julian Wiedmann Date: Wed, 18 Mar 2020 13:54:49 +0100 Subject: [PATCH] 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: Julian Wiedmann Signed-off-by: David S. Miller --- drivers/s390/net/qeth_core_main.c | 6 +++++- drivers/s390/net/qeth_ethtool.c | 19 ++++++++++++++++--- 2 files changed, 21 insertions(+), 4 deletions(-) diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c index f13495d9209b..aa493edc0082 100644 --- a/drivers/s390/net/qeth_core_main.c +++ b/drivers/s390/net/qeth_core_main.c @@ -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); diff --git a/drivers/s390/net/qeth_ethtool.c b/drivers/s390/net/qeth_ethtool.c index 19b9c8302d36..715ee0015847 100644 --- a/drivers/s390/net/qeth_ethtool.c +++ b/drivers/s390/net/qeth_ethtool.c @@ -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); } -- 2.11.0