Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 774 insertions, 0 deletions

diff --git a/drivers/net/ntb_netdev.c b/drivers/net/ntb_netdev.c
new file mode 100644
index 000000000..7a0d5e892
--- /dev/null
+++ b/drivers/net/ntb_netdev.c
@@ -0,0 +1,774 @@
+// SPDX-License-Identifier: GPL-2.0-only OR BSD-3-Clause
+/*
+ * PCIe NTB Network Linux driver
+ */
+#include <linux/etherdevice.h>
+#include <linux/ethtool.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/ntb.h>
+#include <linux/ntb_transport.h>
+#include <linux/slab.h>
+
+#define NTB_NETDEV_VER	"0.7"
+
+MODULE_DESCRIPTION(KBUILD_MODNAME);
+MODULE_VERSION(NTB_NETDEV_VER);
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Intel Corporation");
+
+/* Time in usecs for tx resource reaper */
+static unsigned int tx_time = 1;
+
+/* Number of descriptors to free before resuming tx */
+static unsigned int tx_start = 10;
+
+/* Number of descriptors still available before stop upper layer tx */
+static unsigned int tx_stop = 5;
+
+#define NTB_NETDEV_MAX_QUEUES		64
+#define NTB_NETDEV_DEFAULT_QUEUES	1
+
+struct ntb_netdev;
+
+struct ntb_netdev_queue {
+	struct ntb_netdev *ntdev;
+	struct ntb_transport_qp *qp;
+	struct timer_list tx_timer;
+	u16 qid;
+};
+
+struct ntb_netdev {
+	struct pci_dev *pdev;
+	struct device *client_dev;
+	struct net_device *ndev;
+	unsigned int num_queues;
+	struct ntb_netdev_queue *queues;
+};
+
+#define	NTB_TX_TIMEOUT_MS	1000
+#define	NTB_RXQ_SIZE		100
+
+static void ntb_netdev_update_carrier(struct ntb_netdev *dev)
+{
+	struct net_device *ndev;
+	bool any_up = false;
+	unsigned int i;
+
+	ndev = dev->ndev;
+
+	for (i = 0; i < dev->num_queues; i++) {
+		if (ntb_transport_link_query(dev->queues[i].qp)) {
+			any_up = true;
+			break;
+		}
+	}
+
+	if (any_up)
+		netif_carrier_on(ndev);
+	else
+		netif_carrier_off(ndev);
+}
+
+static void ntb_netdev_queue_rx_drain(struct ntb_netdev_queue *queue)
+{
+	struct sk_buff *skb;
+	int len;
+
+	while ((skb = ntb_transport_rx_remove(queue->qp, &len)))
+		dev_kfree_skb(skb);
+}
+
+static int ntb_netdev_queue_rx_fill(struct net_device *ndev,
+				    struct ntb_netdev_queue *queue)
+{
+	struct sk_buff *skb;
+	int rc, i;
+
+	for (i = 0; i < NTB_RXQ_SIZE; i++) {
+		skb = netdev_alloc_skb(ndev, ndev->mtu + ETH_HLEN);
+		if (!skb)
+			return -ENOMEM;
+
+		rc = ntb_transport_rx_enqueue(queue->qp, skb, skb->data,
+					      ndev->mtu + ETH_HLEN);
+		if (rc) {
+			dev_kfree_skb(skb);
+			return rc;
+		}
+	}
+
+	return 0;
+}
+
+static void ntb_netdev_event_handler(void *data, int link_is_up)
+{
+	struct ntb_netdev_queue *q = data;
+	struct ntb_netdev *dev = q->ntdev;
+	struct net_device *ndev;
+
+	ndev = dev->ndev;
+
+	netdev_dbg(ndev, "Event %x, Link %x, qp %u\n", link_is_up,
+		   ntb_transport_link_query(q->qp), q->qid);
+
+	if (netif_running(ndev)) {
+		if (link_is_up)
+			netif_wake_subqueue(ndev, q->qid);
+		else
+			netif_stop_subqueue(ndev, q->qid);
+	}
+
+	ntb_netdev_update_carrier(dev);
+}
+
+static void ntb_netdev_rx_handler(struct ntb_transport_qp *qp, void *qp_data,
+				  void *data, int len)
+{
+	struct ntb_netdev_queue *q = qp_data;
+	struct ntb_netdev *dev = q->ntdev;
+	struct pcpu_sw_netstats *tstats;
+	struct sk_buff *skb, *new_skb;
+	struct net_device *ndev;
+	unsigned long flags;
+	int rc;
+
+	ndev = dev->ndev;
+	skb = data;
+	if (!skb)
+		return;
+
+	netdev_dbg(ndev, "%s: %d byte payload received\n", __func__, len);
+
+	if (len < 0) {
+		DEV_STATS_INC(ndev, rx_errors);
+		DEV_STATS_INC(ndev, rx_length_errors);
+		goto enqueue_again;
+	}
+
+	tstats = this_cpu_ptr(ndev->tstats);
+	flags = u64_stats_update_begin_irqsave(&tstats->syncp);
+	u64_stats_inc(&tstats->rx_packets);
+	u64_stats_add(&tstats->rx_bytes, len);
+	u64_stats_update_end_irqrestore(&tstats->syncp, flags);
+
+	new_skb = netdev_alloc_skb(ndev, ndev->mtu + ETH_HLEN);
+	if (!new_skb) {
+		DEV_STATS_INC(ndev, rx_dropped);
+		goto enqueue_again;
+	}
+
+	skb_put(skb, len);
+	skb->protocol = eth_type_trans(skb, ndev);
+	skb->ip_summed = CHECKSUM_NONE;
+	skb_record_rx_queue(skb, q->qid);
+
+	netif_rx(skb);
+
+	skb = new_skb;
+
+enqueue_again:
+	rc = ntb_transport_rx_enqueue(qp, skb, skb->data, ndev->mtu + ETH_HLEN);
+	if (rc) {
+		dev_kfree_skb_any(skb);
+		DEV_STATS_INC(ndev, rx_errors);
+		DEV_STATS_INC(ndev, rx_fifo_errors);
+	}
+}
+
+static int __ntb_netdev_maybe_stop_tx(struct net_device *netdev,
+				      struct ntb_netdev_queue *q, int size)
+{
+	netif_stop_subqueue(netdev, q->qid);
+
+	/* Make sure to see the latest value of ntb_transport_tx_free_entry()
+	 * since the queue was last started.
+	 */
+	smp_mb();
+
+	if (likely(ntb_transport_tx_free_entry(q->qp) < size)) {
+		mod_timer(&q->tx_timer, jiffies + usecs_to_jiffies(tx_time));
+		return -EBUSY;
+	}
+
+	/* The subqueue must be kept stopped if the link is down */
+	if (ntb_transport_link_query(q->qp))
+		netif_start_subqueue(netdev, q->qid);
+
+	return 0;
+}
+
+static int ntb_netdev_maybe_stop_tx(struct net_device *ndev,
+				    struct ntb_netdev_queue *q, int size)
+{
+	if (__netif_subqueue_stopped(ndev, q->qid))
+		return -EBUSY;
+
+	if (ntb_transport_tx_free_entry(q->qp) >= size)
+		return 0;
+
+	return __ntb_netdev_maybe_stop_tx(ndev, q, size);
+}
+
+static void ntb_netdev_tx_handler(struct ntb_transport_qp *qp, void *qp_data,
+				  void *data, int len)
+{
+	struct ntb_netdev_queue *q = qp_data;
+	struct ntb_netdev *dev = q->ntdev;
+	struct pcpu_sw_netstats *tstats;
+	struct net_device *ndev;
+	struct sk_buff *skb;
+	unsigned long flags;
+	bool registered;
+
+	ndev = dev->ndev;
+	skb = data;
+	if (!skb || !ndev)
+		return;
+
+	rcu_read_lock();
+	registered = READ_ONCE(ndev->reg_state) == NETREG_REGISTERED;
+	if (!registered)
+		goto free_skb;
+
+	if (len > 0) {
+		/* The memcpy kthread can migrate, so pin the per-CPU update. */
+		tstats = get_cpu_ptr(ndev->tstats);
+		flags = u64_stats_update_begin_irqsave(&tstats->syncp);
+		u64_stats_inc(&tstats->tx_packets);
+		u64_stats_add(&tstats->tx_bytes, skb->len);
+		u64_stats_update_end_irqrestore(&tstats->syncp, flags);
+		put_cpu_ptr(ndev->tstats);
+	} else {
+		DEV_STATS_INC(ndev, tx_errors);
+		DEV_STATS_INC(ndev, tx_aborted_errors);
+	}
+
+free_skb:
+	dev_kfree_skb_any(skb);
+
+	if (registered && ntb_transport_tx_free_entry(qp) >= tx_start) {
+		/* Make sure anybody stopping the queue after this sees the new
+		 * value of ntb_transport_tx_free_entry()
+		 */
+		smp_mb();
+		if (__netif_subqueue_stopped(ndev, q->qid) &&
+		    ntb_transport_link_query(q->qp))
+			netif_wake_subqueue(ndev, q->qid);
+	}
+	rcu_read_unlock();
+}
+
+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)
+{
+	struct ntb_netdev *dev = netdev_priv(ndev);
+	u16 qid = skb_get_queue_mapping(skb);
+	struct ntb_netdev_queue *q;
+	int rc;
+
+	q = &dev->queues[qid];
+
+	if (unlikely(ntb_netdev_maybe_stop_tx(ndev, q, tx_stop)))
+		return NETDEV_TX_BUSY;
+
+	rc = ntb_transport_tx_enqueue(q->qp, skb, skb->data, skb->len);
+	if (rc) {
+		if (rc == -EAGAIN || rc == -EBUSY) {
+			netif_stop_subqueue(ndev, q->qid);
+			mod_timer(&q->tx_timer,
+				  jiffies + usecs_to_jiffies(tx_time));
+			return NETDEV_TX_BUSY;
+		}
+
+		goto drop;
+	}
+
+	/* check for next submit */
+	ntb_netdev_maybe_stop_tx(ndev, q, tx_stop);
+
+	return NETDEV_TX_OK;
+
+drop:
+	dev_kfree_skb_any(skb);
+	DEV_STATS_INC(ndev, tx_dropped);
+	return NETDEV_TX_OK;
+}
+
+static void ntb_netdev_tx_timer(struct timer_list *t)
+{
+	struct ntb_netdev_queue *q = timer_container_of(q, t, tx_timer);
+	struct ntb_netdev *dev = q->ntdev;
+	struct net_device *ndev;
+
+	ndev = dev->ndev;
+
+	if (ntb_transport_tx_free_entry(q->qp) < tx_stop) {
+		mod_timer(&q->tx_timer, jiffies + usecs_to_jiffies(tx_time));
+	} else {
+		/* Make sure anybody stopping the queue after this sees the new
+		 * value of ntb_transport_tx_free_entry()
+		 */
+		smp_mb();
+
+		/* The subqueue must be kept stopped if the link is down */
+		if (__netif_subqueue_stopped(ndev, q->qid) &&
+		    ntb_transport_link_query(q->qp))
+			netif_wake_subqueue(ndev, q->qid);
+	}
+}
+
+static int ntb_netdev_open(struct net_device *ndev)
+{
+	struct ntb_netdev *dev = netdev_priv(ndev);
+	struct ntb_netdev_queue *queue;
+	unsigned int q;
+	int rc = 0;
+
+	/* Add some empty rx bufs for each queue */
+	for (q = 0; q < dev->num_queues; q++) {
+		queue = &dev->queues[q];
+
+		rc = ntb_netdev_queue_rx_fill(ndev, queue);
+		if (rc)
+			goto err;
+
+		timer_setup(&queue->tx_timer, ntb_netdev_tx_timer, 0);
+	}
+
+	netif_carrier_off(ndev);
+	netif_tx_stop_all_queues(ndev);
+
+	for (q = 0; q < dev->num_queues; q++)
+		ntb_transport_link_up(dev->queues[q].qp);
+
+	return 0;
+
+err:
+	for (q = 0; q < dev->num_queues; q++) {
+		queue = &dev->queues[q];
+		ntb_netdev_queue_rx_drain(queue);
+	}
+	return rc;
+}
+
+static int ntb_netdev_close(struct net_device *ndev)
+{
+	struct ntb_netdev *dev = netdev_priv(ndev);
+	struct ntb_netdev_queue *queue;
+	unsigned int q;
+
+	netif_tx_stop_all_queues(ndev);
+	netif_carrier_off(ndev);
+
+	for (q = 0; q < dev->num_queues; q++) {
+		queue = &dev->queues[q];
+
+		ntb_transport_link_down(queue->qp);
+		ntb_netdev_queue_rx_drain(queue);
+		timer_delete_sync(&queue->tx_timer);
+	}
+
+	return 0;
+}
+
+static int ntb_netdev_change_mtu(struct net_device *ndev, int new_mtu)
+{
+	struct ntb_netdev *dev = netdev_priv(ndev);
+	struct ntb_netdev_queue *queue;
+	struct sk_buff *skb;
+	unsigned int q, i;
+	int len, rc = 0;
+
+	if (new_mtu > ntb_transport_max_size(dev->queues[0].qp) - ETH_HLEN)
+		return -EINVAL;
+
+	if (!netif_running(ndev)) {
+		WRITE_ONCE(ndev->mtu, new_mtu);
+		return 0;
+	}
+
+	/* Bring down the link and dispose of posted rx entries */
+	for (q = 0; q < dev->num_queues; q++)
+		ntb_transport_link_down(dev->queues[q].qp);
+
+	if (ndev->mtu < new_mtu) {
+		for (q = 0; q < dev->num_queues; q++) {
+			queue = &dev->queues[q];
+
+			for (i = 0;
+			     (skb = ntb_transport_rx_remove(queue->qp, &len));
+			     i++)
+				dev_kfree_skb(skb);
+
+			for (; i; i--) {
+				skb = netdev_alloc_skb(ndev,
+						       new_mtu + ETH_HLEN);
+				if (!skb) {
+					rc = -ENOMEM;
+					goto err;
+				}
+
+				rc = ntb_transport_rx_enqueue(queue->qp, skb,
+							      skb->data,
+							      new_mtu +
+							      ETH_HLEN);
+				if (rc) {
+					dev_kfree_skb(skb);
+					goto err;
+				}
+			}
+		}
+	}
+
+	WRITE_ONCE(ndev->mtu, new_mtu);
+
+	for (q = 0; q < dev->num_queues; q++)
+		ntb_transport_link_up(dev->queues[q].qp);
+
+	return 0;
+
+err:
+	for (q = 0; q < dev->num_queues; q++) {
+		struct ntb_netdev_queue *queue = &dev->queues[q];
+
+		ntb_transport_link_down(queue->qp);
+
+		ntb_netdev_queue_rx_drain(queue);
+	}
+
+	netdev_err(ndev, "Error changing MTU, device inoperable\n");
+	return rc;
+}
+
+static const struct net_device_ops ntb_netdev_ops = {
+	.ndo_open = ntb_netdev_open,
+	.ndo_stop = ntb_netdev_close,
+	.ndo_start_xmit = ntb_netdev_start_xmit,
+	.ndo_change_mtu = ntb_netdev_change_mtu,
+	.ndo_set_mac_address = eth_mac_addr,
+};
+
+static void ntb_get_drvinfo(struct net_device *ndev,
+			    struct ethtool_drvinfo *info)
+{
+	struct ntb_netdev *dev = netdev_priv(ndev);
+
+	strscpy(info->driver, KBUILD_MODNAME, sizeof(info->driver));
+	strscpy(info->version, NTB_NETDEV_VER, sizeof(info->version));
+	strscpy(info->bus_info, pci_name(dev->pdev), sizeof(info->bus_info));
+}
+
+static int ntb_get_link_ksettings(struct net_device *dev,
+				  struct ethtool_link_ksettings *cmd)
+{
+	ethtool_link_ksettings_zero_link_mode(cmd, supported);
+	ethtool_link_ksettings_add_link_mode(cmd, supported, Backplane);
+	ethtool_link_ksettings_zero_link_mode(cmd, advertising);
+	ethtool_link_ksettings_add_link_mode(cmd, advertising, Backplane);
+
+	cmd->base.speed = SPEED_UNKNOWN;
+	cmd->base.duplex = DUPLEX_FULL;
+	cmd->base.port = PORT_OTHER;
+	cmd->base.phy_address = 0;
+	cmd->base.autoneg = AUTONEG_ENABLE;
+
+	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,
+	.get_channels = ntb_get_channels,
+	.set_channels = ntb_set_channels,
+};
+
+static int ntb_netdev_probe(struct device *client_dev)
+{
+	struct ntb_dev *ntb;
+	struct net_device *ndev;
+	struct pci_dev *pdev;
+	struct ntb_netdev *dev;
+	unsigned int q;
+	int rc;
+
+	ntb = dev_ntb(client_dev->parent);
+	pdev = ntb->pdev;
+	if (!pdev)
+		return -ENODEV;
+
+	ndev = alloc_etherdev_mq(sizeof(*dev), NTB_NETDEV_MAX_QUEUES);
+	if (!ndev)
+		return -ENOMEM;
+
+	SET_NETDEV_DEV(ndev, client_dev);
+
+	dev = netdev_priv(ndev);
+	dev->ndev = ndev;
+	dev->pdev = pdev;
+	dev->client_dev = client_dev;
+	dev->num_queues = 0;
+
+	dev->queues = kzalloc_objs(*dev->queues, NTB_NETDEV_MAX_QUEUES);
+	if (!dev->queues) {
+		rc = -ENOMEM;
+		goto err_free_netdev;
+	}
+
+	ndev->features = NETIF_F_HIGHDMA;
+	ndev->pcpu_stat_type = NETDEV_PCPU_STAT_TSTATS;
+
+	ndev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
+
+	ndev->hw_features = ndev->features;
+	ndev->watchdog_timeo = msecs_to_jiffies(NTB_TX_TIMEOUT_MS);
+
+	eth_random_addr(ndev->perm_addr);
+	dev_addr_set(ndev, ndev->perm_addr);
+
+	ndev->netdev_ops = &ntb_netdev_ops;
+	ndev->ethtool_ops = &ntb_ethtool_ops;
+
+	ndev->min_mtu = 0;
+	ndev->max_mtu = ETH_MAX_MTU;
+
+	for (q = 0; q < NTB_NETDEV_DEFAULT_QUEUES; q++) {
+		struct ntb_netdev_queue *queue = &dev->queues[q];
+
+		queue->ntdev = dev;
+		queue->qid = q;
+		queue->qp = ntb_transport_create_queue(queue, client_dev,
+						       &ntb_netdev_handlers);
+		if (!queue->qp)
+			break;
+
+		dev->num_queues++;
+	}
+
+	if (!dev->num_queues) {
+		rc = -EIO;
+		goto err_free_queues;
+	}
+
+	rc = netif_set_real_num_queues(ndev, dev->num_queues, dev->num_queues);
+	if (rc)
+		goto err_free_qps;
+
+	ndev->mtu = ntb_transport_max_size(dev->queues[0].qp) - ETH_HLEN;
+
+	rc = register_netdev(ndev);
+	if (rc)
+		goto err_free_qps;
+
+	dev_set_drvdata(client_dev, ndev);
+	dev_info(&pdev->dev, "%s created with %u queue pairs\n",
+		 ndev->name, dev->num_queues);
+	return 0;
+
+err_free_qps:
+	for (q = 0; q < dev->num_queues; q++)
+		ntb_transport_free_queue(dev->queues[q].qp);
+
+err_free_queues:
+	kfree(dev->queues);
+
+err_free_netdev:
+	free_netdev(ndev);
+	return rc;
+}
+
+static void ntb_netdev_remove(struct device *client_dev)
+{
+	struct net_device *ndev = dev_get_drvdata(client_dev);
+	struct ntb_netdev *dev = netdev_priv(ndev);
+	unsigned int q;
+
+	unregister_netdev(ndev);
+	for (q = 0; q < dev->num_queues; q++)
+		ntb_transport_free_queue(dev->queues[q].qp);
+
+	kfree(dev->queues);
+	free_netdev(ndev);
+}
+
+static struct ntb_transport_client ntb_netdev_client = {
+	.driver.name = KBUILD_MODNAME,
+	.driver.owner = THIS_MODULE,
+	.probe = ntb_netdev_probe,
+	.remove = ntb_netdev_remove,
+};
+
+static int __init ntb_netdev_init_module(void)
+{
+	int rc;
+
+	rc = ntb_transport_register_client_dev(KBUILD_MODNAME);
+	if (rc)
+		return rc;
+
+	rc = ntb_transport_register_client(&ntb_netdev_client);
+	if (rc) {
+		ntb_transport_unregister_client_dev(KBUILD_MODNAME);
+		return rc;
+	}
+
+	return 0;
+}
+late_initcall(ntb_netdev_init_module);
+
+static void __exit ntb_netdev_exit_module(void)
+{
+	ntb_transport_unregister_client(&ntb_netdev_client);
+	ntb_transport_unregister_client_dev(KBUILD_MODNAME);
+}
+module_exit(ntb_netdev_exit_module);