1 files changed, 652 insertions, 0 deletions

diff --git a/drivers/net/ethernet/sfc/falcon/tx.c b/drivers/net/ethernet/sfc/falcon/tx.c
new file mode 100644
index 000000000..3409bbf5b
--- /dev/null
+++ b/drivers/net/ethernet/sfc/falcon/tx.c
@@ -0,0 +1,652 @@
+/****************************************************************************
+ * Driver for Solarflare network controllers and boards
+ * Copyright 2005-2006 Fen Systems Ltd.
+ * Copyright 2005-2013 Solarflare Communications Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation, incorporated herein by reference.
+ */
+
+#include <linux/pci.h>
+#include <linux/tcp.h>
+#include <linux/ip.h>
+#include <linux/in.h>
+#include <linux/ipv6.h>
+#include <linux/slab.h>
+#include <net/ipv6.h>
+#include <linux/if_ether.h>
+#include <linux/highmem.h>
+#include <linux/cache.h>
+#include "net_driver.h"
+#include "efx.h"
+#include "io.h"
+#include "nic.h"
+#include "tx.h"
+#include "workarounds.h"
+
+static inline u8 *ef4_tx_get_copy_buffer(struct ef4_tx_queue *tx_queue,
+					 struct ef4_tx_buffer *buffer)
+{
+	unsigned int index = ef4_tx_queue_get_insert_index(tx_queue);
+	struct ef4_buffer *page_buf =
+		&tx_queue->cb_page[index >> (PAGE_SHIFT - EF4_TX_CB_ORDER)];
+	unsigned int offset =
+		((index << EF4_TX_CB_ORDER) + NET_IP_ALIGN) & (PAGE_SIZE - 1);
+
+	if (unlikely(!page_buf->addr) &&
+	    ef4_nic_alloc_buffer(tx_queue->efx, page_buf, PAGE_SIZE,
+				 GFP_ATOMIC))
+		return NULL;
+	buffer->dma_addr = page_buf->dma_addr + offset;
+	buffer->unmap_len = 0;
+	return (u8 *)page_buf->addr + offset;
+}
+
+u8 *ef4_tx_get_copy_buffer_limited(struct ef4_tx_queue *tx_queue,
+				   struct ef4_tx_buffer *buffer, size_t len)
+{
+	if (len > EF4_TX_CB_SIZE)
+		return NULL;
+	return ef4_tx_get_copy_buffer(tx_queue, buffer);
+}
+
+static void ef4_dequeue_buffer(struct ef4_tx_queue *tx_queue,
+			       struct ef4_tx_buffer *buffer,
+			       unsigned int *pkts_compl,
+			       unsigned int *bytes_compl)
+{
+	if (buffer->unmap_len) {
+		struct device *dma_dev = &tx_queue->efx->pci_dev->dev;
+		dma_addr_t unmap_addr = buffer->dma_addr - buffer->dma_offset;
+		if (buffer->flags & EF4_TX_BUF_MAP_SINGLE)
+			dma_unmap_single(dma_dev, unmap_addr, buffer->unmap_len,
+					 DMA_TO_DEVICE);
+		else
+			dma_unmap_page(dma_dev, unmap_addr, buffer->unmap_len,
+				       DMA_TO_DEVICE);
+		buffer->unmap_len = 0;
+	}
+
+	if (buffer->flags & EF4_TX_BUF_SKB) {
+		(*pkts_compl)++;
+		(*bytes_compl) += buffer->skb->len;
+		dev_consume_skb_any((struct sk_buff *)buffer->skb);
+		netif_vdbg(tx_queue->efx, tx_done, tx_queue->efx->net_dev,
+			   "TX queue %d transmission id %x complete\n",
+			   tx_queue->queue, tx_queue->read_count);
+	}
+
+	buffer->len = 0;
+	buffer->flags = 0;
+}
+
+unsigned int ef4_tx_max_skb_descs(struct ef4_nic *efx)
+{
+	/* This is probably too much since we don't have any TSO support;
+	 * it's a left-over from when we had Software TSO.  But it's safer
+	 * to leave it as-is than try to determine a new bound.
+	 */
+	/* Header and payload descriptor for each output segment, plus
+	 * one for every input fragment boundary within a segment
+	 */
+	unsigned int max_descs = EF4_TSO_MAX_SEGS * 2 + MAX_SKB_FRAGS;
+
+	/* Possibly one more per segment for the alignment workaround,
+	 * or for option descriptors
+	 */
+	if (EF4_WORKAROUND_5391(efx))
+		max_descs += EF4_TSO_MAX_SEGS;
+
+	/* Possibly more for PCIe page boundaries within input fragments */
+	if (PAGE_SIZE > EF4_PAGE_SIZE)
+		max_descs += max_t(unsigned int, MAX_SKB_FRAGS,
+				   DIV_ROUND_UP(GSO_MAX_SIZE, EF4_PAGE_SIZE));
+
+	return max_descs;
+}
+
+static void ef4_tx_maybe_stop_queue(struct ef4_tx_queue *txq1)
+{
+	/* We need to consider both queues that the net core sees as one */
+	struct ef4_tx_queue *txq2 = ef4_tx_queue_partner(txq1);
+	struct ef4_nic *efx = txq1->efx;
+	unsigned int fill_level;
+
+	fill_level = max(txq1->insert_count - txq1->old_read_count,
+			 txq2->insert_count - txq2->old_read_count);
+	if (likely(fill_level < efx->txq_stop_thresh))
+		return;
+
+	/* We used the stale old_read_count above, which gives us a
+	 * pessimistic estimate of the fill level (which may even
+	 * validly be >= efx->txq_entries).  Now try again using
+	 * read_count (more likely to be a cache miss).
+	 *
+	 * If we read read_count and then conditionally stop the
+	 * queue, it is possible for the completion path to race with
+	 * us and complete all outstanding descriptors in the middle,
+	 * after which there will be no more completions to wake it.
+	 * Therefore we stop the queue first, then read read_count
+	 * (with a memory barrier to ensure the ordering), then
+	 * restart the queue if the fill level turns out to be low
+	 * enough.
+	 */
+	netif_tx_stop_queue(txq1->core_txq);
+	smp_mb();
+	txq1->old_read_count = READ_ONCE(txq1->read_count);
+	txq2->old_read_count = READ_ONCE(txq2->read_count);
+
+	fill_level = max(txq1->insert_count - txq1->old_read_count,
+			 txq2->insert_count - txq2->old_read_count);
+	EF4_BUG_ON_PARANOID(fill_level >= efx->txq_entries);
+	if (likely(fill_level < efx->txq_stop_thresh)) {
+		smp_mb();
+		if (likely(!efx->loopback_selftest))
+			netif_tx_start_queue(txq1->core_txq);
+	}
+}
+
+static int ef4_enqueue_skb_copy(struct ef4_tx_queue *tx_queue,
+				struct sk_buff *skb)
+{
+	unsigned int min_len = tx_queue->tx_min_size;
+	unsigned int copy_len = skb->len;
+	struct ef4_tx_buffer *buffer;
+	u8 *copy_buffer;
+	int rc;
+
+	EF4_BUG_ON_PARANOID(copy_len > EF4_TX_CB_SIZE);
+
+	buffer = ef4_tx_queue_get_insert_buffer(tx_queue);
+
+	copy_buffer = ef4_tx_get_copy_buffer(tx_queue, buffer);
+	if (unlikely(!copy_buffer))
+		return -ENOMEM;
+
+	rc = skb_copy_bits(skb, 0, copy_buffer, copy_len);
+	EF4_WARN_ON_PARANOID(rc);
+	if (unlikely(copy_len < min_len)) {
+		memset(copy_buffer + copy_len, 0, min_len - copy_len);
+		buffer->len = min_len;
+	} else {
+		buffer->len = copy_len;
+	}
+
+	buffer->skb = skb;
+	buffer->flags = EF4_TX_BUF_SKB;
+
+	++tx_queue->insert_count;
+	return rc;
+}
+
+static struct ef4_tx_buffer *ef4_tx_map_chunk(struct ef4_tx_queue *tx_queue,
+					      dma_addr_t dma_addr,
+					      size_t len)
+{
+	const struct ef4_nic_type *nic_type = tx_queue->efx->type;
+	struct ef4_tx_buffer *buffer;
+	unsigned int dma_len;
+
+	/* Map the fragment taking account of NIC-dependent DMA limits. */
+	do {
+		buffer = ef4_tx_queue_get_insert_buffer(tx_queue);
+		dma_len = nic_type->tx_limit_len(tx_queue, dma_addr, len);
+
+		buffer->len = dma_len;
+		buffer->dma_addr = dma_addr;
+		buffer->flags = EF4_TX_BUF_CONT;
+		len -= dma_len;
+		dma_addr += dma_len;
+		++tx_queue->insert_count;
+	} while (len);
+
+	return buffer;
+}
+
+/* Map all data from an SKB for DMA and create descriptors on the queue.
+ */
+static int ef4_tx_map_data(struct ef4_tx_queue *tx_queue, struct sk_buff *skb)
+{
+	struct ef4_nic *efx = tx_queue->efx;
+	struct device *dma_dev = &efx->pci_dev->dev;
+	unsigned int frag_index, nr_frags;
+	dma_addr_t dma_addr, unmap_addr;
+	unsigned short dma_flags;
+	size_t len, unmap_len;
+
+	nr_frags = skb_shinfo(skb)->nr_frags;
+	frag_index = 0;
+
+	/* Map header data. */
+	len = skb_headlen(skb);
+	dma_addr = dma_map_single(dma_dev, skb->data, len, DMA_TO_DEVICE);
+	dma_flags = EF4_TX_BUF_MAP_SINGLE;
+	unmap_len = len;
+	unmap_addr = dma_addr;
+
+	if (unlikely(dma_mapping_error(dma_dev, dma_addr)))
+		return -EIO;
+
+	/* Add descriptors for each fragment. */
+	do {
+		struct ef4_tx_buffer *buffer;
+		skb_frag_t *fragment;
+
+		buffer = ef4_tx_map_chunk(tx_queue, dma_addr, len);
+
+		/* The final descriptor for a fragment is responsible for
+		 * unmapping the whole fragment.
+		 */
+		buffer->flags = EF4_TX_BUF_CONT | dma_flags;
+		buffer->unmap_len = unmap_len;
+		buffer->dma_offset = buffer->dma_addr - unmap_addr;
+
+		if (frag_index >= nr_frags) {
+			/* Store SKB details with the final buffer for
+			 * the completion.
+			 */
+			buffer->skb = skb;
+			buffer->flags = EF4_TX_BUF_SKB | dma_flags;
+			return 0;
+		}
+
+		/* Move on to the next fragment. */
+		fragment = &skb_shinfo(skb)->frags[frag_index++];
+		len = skb_frag_size(fragment);
+		dma_addr = skb_frag_dma_map(dma_dev, fragment,
+				0, len, DMA_TO_DEVICE);
+		dma_flags = 0;
+		unmap_len = len;
+		unmap_addr = dma_addr;
+
+		if (unlikely(dma_mapping_error(dma_dev, dma_addr)))
+			return -EIO;
+	} while (1);
+}
+
+/* Remove buffers put into a tx_queue.  None of the buffers must have
+ * an skb attached.
+ */
+static void ef4_enqueue_unwind(struct ef4_tx_queue *tx_queue)
+{
+	struct ef4_tx_buffer *buffer;
+
+	/* Work backwards until we hit the original insert pointer value */
+	while (tx_queue->insert_count != tx_queue->write_count) {
+		--tx_queue->insert_count;
+		buffer = __ef4_tx_queue_get_insert_buffer(tx_queue);
+		ef4_dequeue_buffer(tx_queue, buffer, NULL, NULL);
+	}
+}
+
+/*
+ * Add a socket buffer to a TX queue
+ *
+ * This maps all fragments of a socket buffer for DMA and adds them to
+ * the TX queue.  The queue's insert pointer will be incremented by
+ * the number of fragments in the socket buffer.
+ *
+ * If any DMA mapping fails, any mapped fragments will be unmapped,
+ * the queue's insert pointer will be restored to its original value.
+ *
+ * This function is split out from ef4_hard_start_xmit to allow the
+ * loopback test to direct packets via specific TX queues.
+ *
+ * Returns NETDEV_TX_OK.
+ * You must hold netif_tx_lock() to call this function.
+ */
+netdev_tx_t ef4_enqueue_skb(struct ef4_tx_queue *tx_queue, struct sk_buff *skb)
+{
+	bool data_mapped = false;
+	unsigned int skb_len;
+
+	skb_len = skb->len;
+	EF4_WARN_ON_PARANOID(skb_is_gso(skb));
+
+	if (skb_len < tx_queue->tx_min_size ||
+			(skb->data_len && skb_len <= EF4_TX_CB_SIZE)) {
+		/* Pad short packets or coalesce short fragmented packets. */
+		if (ef4_enqueue_skb_copy(tx_queue, skb))
+			goto err;
+		tx_queue->cb_packets++;
+		data_mapped = true;
+	}
+
+	/* Map for DMA and create descriptors if we haven't done so already. */
+	if (!data_mapped && (ef4_tx_map_data(tx_queue, skb)))
+		goto err;
+
+	/* Update BQL */
+	netdev_tx_sent_queue(tx_queue->core_txq, skb_len);
+
+	/* Pass off to hardware */
+	if (!skb->xmit_more || netif_xmit_stopped(tx_queue->core_txq)) {
+		struct ef4_tx_queue *txq2 = ef4_tx_queue_partner(tx_queue);
+
+		/* There could be packets left on the partner queue if those
+		 * SKBs had skb->xmit_more set. If we do not push those they
+		 * could be left for a long time and cause a netdev watchdog.
+		 */
+		if (txq2->xmit_more_available)
+			ef4_nic_push_buffers(txq2);
+
+		ef4_nic_push_buffers(tx_queue);
+	} else {
+		tx_queue->xmit_more_available = skb->xmit_more;
+	}
+
+	tx_queue->tx_packets++;
+
+	ef4_tx_maybe_stop_queue(tx_queue);
+
+	return NETDEV_TX_OK;
+
+
+err:
+	ef4_enqueue_unwind(tx_queue);
+	dev_kfree_skb_any(skb);
+	return NETDEV_TX_OK;
+}
+
+/* Remove packets from the TX queue
+ *
+ * This removes packets from the TX queue, up to and including the
+ * specified index.
+ */
+static void ef4_dequeue_buffers(struct ef4_tx_queue *tx_queue,
+				unsigned int index,
+				unsigned int *pkts_compl,
+				unsigned int *bytes_compl)
+{
+	struct ef4_nic *efx = tx_queue->efx;
+	unsigned int stop_index, read_ptr;
+
+	stop_index = (index + 1) & tx_queue->ptr_mask;
+	read_ptr = tx_queue->read_count & tx_queue->ptr_mask;
+
+	while (read_ptr != stop_index) {
+		struct ef4_tx_buffer *buffer = &tx_queue->buffer[read_ptr];
+
+		if (!(buffer->flags & EF4_TX_BUF_OPTION) &&
+		    unlikely(buffer->len == 0)) {
+			netif_err(efx, tx_err, efx->net_dev,
+				  "TX queue %d spurious TX completion id %x\n",
+				  tx_queue->queue, read_ptr);
+			ef4_schedule_reset(efx, RESET_TYPE_TX_SKIP);
+			return;
+		}
+
+		ef4_dequeue_buffer(tx_queue, buffer, pkts_compl, bytes_compl);
+
+		++tx_queue->read_count;
+		read_ptr = tx_queue->read_count & tx_queue->ptr_mask;
+	}
+}
+
+/* Initiate a packet transmission.  We use one channel per CPU
+ * (sharing when we have more CPUs than channels).  On Falcon, the TX
+ * completion events will be directed back to the CPU that transmitted
+ * the packet, which should be cache-efficient.
+ *
+ * Context: non-blocking.
+ * Note that returning anything other than NETDEV_TX_OK will cause the
+ * OS to free the skb.
+ */
+netdev_tx_t ef4_hard_start_xmit(struct sk_buff *skb,
+				struct net_device *net_dev)
+{
+	struct ef4_nic *efx = netdev_priv(net_dev);
+	struct ef4_tx_queue *tx_queue;
+	unsigned index, type;
+
+	EF4_WARN_ON_PARANOID(!netif_device_present(net_dev));
+
+	index = skb_get_queue_mapping(skb);
+	type = skb->ip_summed == CHECKSUM_PARTIAL ? EF4_TXQ_TYPE_OFFLOAD : 0;
+	if (index >= efx->n_tx_channels) {
+		index -= efx->n_tx_channels;
+		type |= EF4_TXQ_TYPE_HIGHPRI;
+	}
+	tx_queue = ef4_get_tx_queue(efx, index, type);
+
+	return ef4_enqueue_skb(tx_queue, skb);
+}
+
+void ef4_init_tx_queue_core_txq(struct ef4_tx_queue *tx_queue)
+{
+	struct ef4_nic *efx = tx_queue->efx;
+
+	/* Must be inverse of queue lookup in ef4_hard_start_xmit() */
+	tx_queue->core_txq =
+		netdev_get_tx_queue(efx->net_dev,
+				    tx_queue->queue / EF4_TXQ_TYPES +
+				    ((tx_queue->queue & EF4_TXQ_TYPE_HIGHPRI) ?
+				     efx->n_tx_channels : 0));
+}
+
+int ef4_setup_tc(struct net_device *net_dev, enum tc_setup_type type,
+		 void *type_data)
+{
+	struct ef4_nic *efx = netdev_priv(net_dev);
+	struct tc_mqprio_qopt *mqprio = type_data;
+	struct ef4_channel *channel;
+	struct ef4_tx_queue *tx_queue;
+	unsigned tc, num_tc;
+	int rc;
+
+	if (type != TC_SETUP_QDISC_MQPRIO)
+		return -EOPNOTSUPP;
+
+	num_tc = mqprio->num_tc;
+
+	if (ef4_nic_rev(efx) < EF4_REV_FALCON_B0 || num_tc > EF4_MAX_TX_TC)
+		return -EINVAL;
+
+	mqprio->hw = TC_MQPRIO_HW_OFFLOAD_TCS;
+
+	if (num_tc == net_dev->num_tc)
+		return 0;
+
+	for (tc = 0; tc < num_tc; tc++) {
+		net_dev->tc_to_txq[tc].offset = tc * efx->n_tx_channels;
+		net_dev->tc_to_txq[tc].count = efx->n_tx_channels;
+	}
+
+	if (num_tc > net_dev->num_tc) {
+		/* Initialise high-priority queues as necessary */
+		ef4_for_each_channel(channel, efx) {
+			ef4_for_each_possible_channel_tx_queue(tx_queue,
+							       channel) {
+				if (!(tx_queue->queue & EF4_TXQ_TYPE_HIGHPRI))
+					continue;
+				if (!tx_queue->buffer) {
+					rc = ef4_probe_tx_queue(tx_queue);
+					if (rc)
+						return rc;
+				}
+				if (!tx_queue->initialised)
+					ef4_init_tx_queue(tx_queue);
+				ef4_init_tx_queue_core_txq(tx_queue);
+			}
+		}
+	} else {
+		/* Reduce number of classes before number of queues */
+		net_dev->num_tc = num_tc;
+	}
+
+	rc = netif_set_real_num_tx_queues(net_dev,
+					  max_t(int, num_tc, 1) *
+					  efx->n_tx_channels);
+	if (rc)
+		return rc;
+
+	/* Do not destroy high-priority queues when they become
+	 * unused.  We would have to flush them first, and it is
+	 * fairly difficult to flush a subset of TX queues.  Leave
+	 * it to ef4_fini_channels().
+	 */
+
+	net_dev->num_tc = num_tc;
+	return 0;
+}
+
+void ef4_xmit_done(struct ef4_tx_queue *tx_queue, unsigned int index)
+{
+	unsigned fill_level;
+	struct ef4_nic *efx = tx_queue->efx;
+	struct ef4_tx_queue *txq2;
+	unsigned int pkts_compl = 0, bytes_compl = 0;
+
+	EF4_BUG_ON_PARANOID(index > tx_queue->ptr_mask);
+
+	ef4_dequeue_buffers(tx_queue, index, &pkts_compl, &bytes_compl);
+	tx_queue->pkts_compl += pkts_compl;
+	tx_queue->bytes_compl += bytes_compl;
+
+	if (pkts_compl > 1)
+		++tx_queue->merge_events;
+
+	/* See if we need to restart the netif queue.  This memory
+	 * barrier ensures that we write read_count (inside
+	 * ef4_dequeue_buffers()) before reading the queue status.
+	 */
+	smp_mb();
+	if (unlikely(netif_tx_queue_stopped(tx_queue->core_txq)) &&
+	    likely(efx->port_enabled) &&
+	    likely(netif_device_present(efx->net_dev))) {
+		txq2 = ef4_tx_queue_partner(tx_queue);
+		fill_level = max(tx_queue->insert_count - tx_queue->read_count,
+				 txq2->insert_count - txq2->read_count);
+		if (fill_level <= efx->txq_wake_thresh)
+			netif_tx_wake_queue(tx_queue->core_txq);
+	}
+
+	/* Check whether the hardware queue is now empty */
+	if ((int)(tx_queue->read_count - tx_queue->old_write_count) >= 0) {
+		tx_queue->old_write_count = READ_ONCE(tx_queue->write_count);
+		if (tx_queue->read_count == tx_queue->old_write_count) {
+			smp_mb();
+			tx_queue->empty_read_count =
+				tx_queue->read_count | EF4_EMPTY_COUNT_VALID;
+		}
+	}
+}
+
+static unsigned int ef4_tx_cb_page_count(struct ef4_tx_queue *tx_queue)
+{
+	return DIV_ROUND_UP(tx_queue->ptr_mask + 1, PAGE_SIZE >> EF4_TX_CB_ORDER);
+}
+
+int ef4_probe_tx_queue(struct ef4_tx_queue *tx_queue)
+{
+	struct ef4_nic *efx = tx_queue->efx;
+	unsigned int entries;
+	int rc;
+
+	/* Create the smallest power-of-two aligned ring */
+	entries = max(roundup_pow_of_two(efx->txq_entries), EF4_MIN_DMAQ_SIZE);
+	EF4_BUG_ON_PARANOID(entries > EF4_MAX_DMAQ_SIZE);
+	tx_queue->ptr_mask = entries - 1;
+
+	netif_dbg(efx, probe, efx->net_dev,
+		  "creating TX queue %d size %#x mask %#x\n",
+		  tx_queue->queue, efx->txq_entries, tx_queue->ptr_mask);
+
+	/* Allocate software ring */
+	tx_queue->buffer = kcalloc(entries, sizeof(*tx_queue->buffer),
+				   GFP_KERNEL);
+	if (!tx_queue->buffer)
+		return -ENOMEM;
+
+	tx_queue->cb_page = kcalloc(ef4_tx_cb_page_count(tx_queue),
+				    sizeof(tx_queue->cb_page[0]), GFP_KERNEL);
+	if (!tx_queue->cb_page) {
+		rc = -ENOMEM;
+		goto fail1;
+	}
+
+	/* Allocate hardware ring */
+	rc = ef4_nic_probe_tx(tx_queue);
+	if (rc)
+		goto fail2;
+
+	return 0;
+
+fail2:
+	kfree(tx_queue->cb_page);
+	tx_queue->cb_page = NULL;
+fail1:
+	kfree(tx_queue->buffer);
+	tx_queue->buffer = NULL;
+	return rc;
+}
+
+void ef4_init_tx_queue(struct ef4_tx_queue *tx_queue)
+{
+	struct ef4_nic *efx = tx_queue->efx;
+
+	netif_dbg(efx, drv, efx->net_dev,
+		  "initialising TX queue %d\n", tx_queue->queue);
+
+	tx_queue->insert_count = 0;
+	tx_queue->write_count = 0;
+	tx_queue->old_write_count = 0;
+	tx_queue->read_count = 0;
+	tx_queue->old_read_count = 0;
+	tx_queue->empty_read_count = 0 | EF4_EMPTY_COUNT_VALID;
+	tx_queue->xmit_more_available = false;
+
+	/* Some older hardware requires Tx writes larger than 32. */
+	tx_queue->tx_min_size = EF4_WORKAROUND_15592(efx) ? 33 : 0;
+
+	/* Set up TX descriptor ring */
+	ef4_nic_init_tx(tx_queue);
+
+	tx_queue->initialised = true;
+}
+
+void ef4_fini_tx_queue(struct ef4_tx_queue *tx_queue)
+{
+	struct ef4_tx_buffer *buffer;
+
+	netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev,
+		  "shutting down TX queue %d\n", tx_queue->queue);
+
+	if (!tx_queue->buffer)
+		return;
+
+	/* Free any buffers left in the ring */
+	while (tx_queue->read_count != tx_queue->write_count) {
+		unsigned int pkts_compl = 0, bytes_compl = 0;
+		buffer = &tx_queue->buffer[tx_queue->read_count & tx_queue->ptr_mask];
+		ef4_dequeue_buffer(tx_queue, buffer, &pkts_compl, &bytes_compl);
+
+		++tx_queue->read_count;
+	}
+	tx_queue->xmit_more_available = false;
+	netdev_tx_reset_queue(tx_queue->core_txq);
+}
+
+void ef4_remove_tx_queue(struct ef4_tx_queue *tx_queue)
+{
+	int i;
+
+	if (!tx_queue->buffer)
+		return;
+
+	netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev,
+		  "destroying TX queue %d\n", tx_queue->queue);
+	ef4_nic_remove_tx(tx_queue);
+
+	if (tx_queue->cb_page) {
+		for (i = 0; i < ef4_tx_cb_page_count(tx_queue); i++)
+			ef4_nic_free_buffer(tx_queue->efx,
+					    &tx_queue->cb_page[i]);
+		kfree(tx_queue->cb_page);
+		tx_queue->cb_page = NULL;
+	}
+
+	kfree(tx_queue->buffer);
+	tx_queue->buffer = NULL;
+}