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net: ntb_netdev: Support ethtool channels for multi-queue

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Support dynamic queue pair addition/removal via ethtool channels.
Use the combined channel count to control the number of netdev TX/RX
queues, each corresponding to a ntb_transport queue pair.

When the number of queues is reduced, tear down and free the removed
ntb_transport queue pairs (not just deactivate them) so other
ntb_transport clients can reuse the freed resources.

When the number of queues is increased, create additional queue pairs up
to NTB_NETDEV_MAX_QUEUES (=64). The effective limit is determined by the
underlying ntb_transport implementation and NTB hardware resources (the
number of MWs), so set_channels may return -ENOSPC if no more QPs can be
allocated.

Keep the default at one queue pair to preserve the previous behavior.

Signed-off-by: Koichiro Den <den@valinux.co.jp>
Link: https://patch.msgid.link/20260305155639.1885517-5-den@valinux.co.jp
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Koichiro Den
2026-03-06 00:56:39 +09:00
committed by Jakub Kicinski
parent b83bf617dc
commit 24d9e73c7e
1 changed files with 151 additions and 6 deletions
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157
drivers/net/ntb_netdev.c
View File

@@ -284,6 +284,12 @@ static void ntb_netdev_tx_handler(struct ntb_transport_qp *qp, void *qp_data,
}
}
static const struct ntb_queue_handlers ntb_netdev_handlers = {
.tx_handler = ntb_netdev_tx_handler,
.rx_handler = ntb_netdev_rx_handler,
.event_handler = ntb_netdev_event_handler,
};
static netdev_tx_t ntb_netdev_start_xmit(struct sk_buff *skb,
struct net_device *ndev)
{
@@ -492,16 +498,155 @@ static int ntb_get_link_ksettings(struct net_device *dev,
return 0;
}
static void ntb_get_channels(struct net_device *ndev,
struct ethtool_channels *channels)
{
struct ntb_netdev *dev = netdev_priv(ndev);
channels->combined_count = dev->num_queues;
channels->max_combined = ndev->num_tx_queues;
}
static int ntb_inc_channels(struct net_device *ndev,
unsigned int old, unsigned int new)
{
struct ntb_netdev *dev = netdev_priv(ndev);
bool running = netif_running(ndev);
struct ntb_netdev_queue *queue;
unsigned int q, created;
int rc;
created = old;
for (q = old; q < new; q++) {
queue = &dev->queues[q];
queue->ntdev = dev;
queue->qid = q;
queue->qp = ntb_transport_create_queue(queue, dev->client_dev,
&ntb_netdev_handlers);
if (!queue->qp) {
rc = -ENOSPC;
goto err_new;
}
created++;
if (!running)
continue;
timer_setup(&queue->tx_timer, ntb_netdev_tx_timer, 0);
rc = ntb_netdev_queue_rx_fill(ndev, queue);
if (rc)
goto err_new;
/*
* Carrier may already be on due to other QPs. Keep the new
* subqueue stopped until we get a Link Up event for this QP.
*/
netif_stop_subqueue(ndev, q);
}
rc = netif_set_real_num_queues(ndev, new, new);
if (rc)
goto err_new;
dev->num_queues = new;
if (running)
for (q = old; q < new; q++)
ntb_transport_link_up(dev->queues[q].qp);
return 0;
err_new:
if (running) {
unsigned int rollback = created;
while (rollback-- > old) {
queue = &dev->queues[rollback];
ntb_transport_link_down(queue->qp);
ntb_netdev_queue_rx_drain(queue);
timer_delete_sync(&queue->tx_timer);
}
}
while (created-- > old) {
queue = &dev->queues[created];
ntb_transport_free_queue(queue->qp);
queue->qp = NULL;
}
return rc;
}
static int ntb_dec_channels(struct net_device *ndev,
unsigned int old, unsigned int new)
{
struct ntb_netdev *dev = netdev_priv(ndev);
bool running = netif_running(ndev);
struct ntb_netdev_queue *queue;
unsigned int q;
int rc;
if (running)
for (q = new; q < old; q++)
netif_stop_subqueue(ndev, q);
rc = netif_set_real_num_queues(ndev, new, new);
if (rc)
goto err;
/* Publish new queue count before invalidating QP pointers */
dev->num_queues = new;
for (q = new; q < old; q++) {
queue = &dev->queues[q];
if (running) {
ntb_transport_link_down(queue->qp);
ntb_netdev_queue_rx_drain(queue);
timer_delete_sync(&queue->tx_timer);
}
ntb_transport_free_queue(queue->qp);
queue->qp = NULL;
}
/*
* It might be the case that the removed queues are the only queues that
* were up, so see if the global carrier needs to change.
*/
ntb_netdev_update_carrier(dev);
return 0;
err:
if (running) {
for (q = new; q < old; q++)
netif_wake_subqueue(ndev, q);
}
return rc;
}
static int ntb_set_channels(struct net_device *ndev,
struct ethtool_channels *channels)
{
struct ntb_netdev *dev = netdev_priv(ndev);
unsigned int new = channels->combined_count;
unsigned int old = dev->num_queues;
if (new == old)
return 0;
if (new < old)
return ntb_dec_channels(ndev, old, new);
else
return ntb_inc_channels(ndev, old, new);
}
static const struct ethtool_ops ntb_ethtool_ops = {
.get_drvinfo = ntb_get_drvinfo,
.get_link = ethtool_op_get_link,
.get_link_ksettings = ntb_get_link_ksettings,
};
static const struct ntb_queue_handlers ntb_netdev_handlers = {
.tx_handler = ntb_netdev_tx_handler,
.rx_handler = ntb_netdev_rx_handler,
.event_handler = ntb_netdev_event_handler,
.get_channels = ntb_get_channels,
.set_channels = ntb_set_channels,
};
static int ntb_netdev_probe(struct device *client_dev)