[dpdk-dev] [PATCH v2 44/51] net/mlx4: separate Tx configuration functions

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

Private functions are now prefixed with "mlx4_" to prevent them from
conflicting with their mlx5 PMD counterparts at link time.

No impact on functionality.

Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
---
 drivers/net/mlx4/Makefile    |   1 +
 drivers/net/mlx4/mlx4.c      | 421 +---------------------------------
 drivers/net/mlx4/mlx4_rxtx.h |   9 +
 drivers/net/mlx4/mlx4_txq.c  | 472 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 483 insertions(+), 420 deletions(-)

diff --git a/drivers/net/mlx4/Makefile b/drivers/net/mlx4/Makefile
index 9549525..0b74fed 100644
--- a/drivers/net/mlx4/Makefile
+++ b/drivers/net/mlx4/Makefile
@@ -40,6 +40,7 @@ SRCS-$(CONFIG_RTE_LIBRTE_MLX4_PMD) += mlx4_ethdev.c
 SRCS-$(CONFIG_RTE_LIBRTE_MLX4_PMD) += mlx4_flow.c
 SRCS-$(CONFIG_RTE_LIBRTE_MLX4_PMD) += mlx4_intr.c
 SRCS-$(CONFIG_RTE_LIBRTE_MLX4_PMD) += mlx4_rxtx.c
+SRCS-$(CONFIG_RTE_LIBRTE_MLX4_PMD) += mlx4_txq.c
 SRCS-$(CONFIG_RTE_LIBRTE_MLX4_PMD) += mlx4_utils.c
 
 # Basic CFLAGS.
diff --git a/drivers/net/mlx4/mlx4.c b/drivers/net/mlx4/mlx4.c
index cff57c2..ee3fc24 100644
--- a/drivers/net/mlx4/mlx4.c
+++ b/drivers/net/mlx4/mlx4.c
@@ -56,9 +56,6 @@
 #include <rte_interrupts.h>
 #include <rte_common.h>
 
-/* Generated configuration header. */
-#include "mlx4_autoconf.h"
-
 /* PMD headers. */
 #include "mlx4.h"
 #include "mlx4_flow.h"
@@ -82,13 +79,6 @@ const char *pmd_mlx4_init_params[] = {
 /* Device configuration. */
 
 static int
-txq_setup(struct rte_eth_dev *dev, struct txq *txq, uint16_t desc,
-	  unsigned int socket, const struct rte_eth_txconf *conf);
-
-static void
-txq_cleanup(struct txq *txq);
-
-static int
 rxq_setup(struct rte_eth_dev *dev, struct rxq *rxq, uint16_t desc,
 	  unsigned int socket, const struct rte_eth_rxconf *conf,
 	  struct rte_mempool *mp);
@@ -132,128 +122,6 @@ mlx4_dev_configure(struct rte_eth_dev *dev)
 	return 0;
 }
 
-/* TX queues handling. */
-
-/**
- * Allocate TX queue elements.
- *
- * @param txq
- *   Pointer to TX queue structure.
- * @param elts_n
- *   Number of elements to allocate.
- *
- * @return
- *   0 on success, negative errno value otherwise and rte_errno is set.
- */
-static int
-txq_alloc_elts(struct txq *txq, unsigned int elts_n)
-{
-	unsigned int i;
-	struct txq_elt (*elts)[elts_n] =
-		rte_calloc_socket("TXQ", 1, sizeof(*elts), 0, txq->socket);
-	int ret = 0;
-
-	if (elts == NULL) {
-		ERROR("%p: can't allocate packets array", (void *)txq);
-		ret = ENOMEM;
-		goto error;
-	}
-	for (i = 0; (i != elts_n); ++i) {
-		struct txq_elt *elt = &(*elts)[i];
-
-		elt->buf = NULL;
-	}
-	DEBUG("%p: allocated and configured %u WRs", (void *)txq, elts_n);
-	txq->elts_n = elts_n;
-	txq->elts = elts;
-	txq->elts_head = 0;
-	txq->elts_tail = 0;
-	txq->elts_comp = 0;
-	/*
-	 * Request send completion every MLX4_PMD_TX_PER_COMP_REQ packets or
-	 * at least 4 times per ring.
-	 */
-	txq->elts_comp_cd_init =
-		((MLX4_PMD_TX_PER_COMP_REQ < (elts_n / 4)) ?
-		 MLX4_PMD_TX_PER_COMP_REQ : (elts_n / 4));
-	txq->elts_comp_cd = txq->elts_comp_cd_init;
-	assert(ret == 0);
-	return 0;
-error:
-	rte_free(elts);
-	DEBUG("%p: failed, freed everything", (void *)txq);
-	assert(ret > 0);
-	rte_errno = ret;
-	return -rte_errno;
-}
-
-/**
- * Free TX queue elements.
- *
- * @param txq
- *   Pointer to TX queue structure.
- */
-static void
-txq_free_elts(struct txq *txq)
-{
-	unsigned int elts_n = txq->elts_n;
-	unsigned int elts_head = txq->elts_head;
-	unsigned int elts_tail = txq->elts_tail;
-	struct txq_elt (*elts)[elts_n] = txq->elts;
-
-	DEBUG("%p: freeing WRs", (void *)txq);
-	txq->elts_n = 0;
-	txq->elts_head = 0;
-	txq->elts_tail = 0;
-	txq->elts_comp = 0;
-	txq->elts_comp_cd = 0;
-	txq->elts_comp_cd_init = 0;
-	txq->elts = NULL;
-	if (elts == NULL)
-		return;
-	while (elts_tail != elts_head) {
-		struct txq_elt *elt = &(*elts)[elts_tail];
-
-		assert(elt->buf != NULL);
-		rte_pktmbuf_free(elt->buf);
-#ifndef NDEBUG
-		/* Poisoning. */
-		memset(elt, 0x77, sizeof(*elt));
-#endif
-		if (++elts_tail == elts_n)
-			elts_tail = 0;
-	}
-	rte_free(elts);
-}
-
-/**
- * Clean up a TX queue.
- *
- * Destroy objects, free allocated memory and reset the structure for reuse.
- *
- * @param txq
- *   Pointer to TX queue structure.
- */
-static void
-txq_cleanup(struct txq *txq)
-{
-	size_t i;
-
-	DEBUG("cleaning up %p", (void *)txq);
-	txq_free_elts(txq);
-	if (txq->qp != NULL)
-		claim_zero(ibv_destroy_qp(txq->qp));
-	if (txq->cq != NULL)
-		claim_zero(ibv_destroy_cq(txq->cq));
-	for (i = 0; (i != RTE_DIM(txq->mp2mr)); ++i) {
-		if (txq->mp2mr[i].mp == NULL)
-			break;
-		assert(txq->mp2mr[i].mr != NULL);
-		claim_zero(ibv_dereg_mr(txq->mp2mr[i].mr));
-	}
-	memset(txq, 0, sizeof(*txq));
-}
-
 struct mlx4_check_mempool_data {
 	int ret;
 	char *start;
@@ -367,293 +235,6 @@ mlx4_mp2mr(struct ibv_pd *pd, struct rte_mempool *mp)
 	return mr;
 }
 
-struct txq_mp2mr_mbuf_check_data {
-	int ret;
-};
-
-/**
- * Callback function for rte_mempool_obj_iter() to check whether a given
- * mempool object looks like a mbuf.
- *
- * @param[in] mp
- *   The mempool pointer
- * @param[in] arg
- *   Context data (struct txq_mp2mr_mbuf_check_data). Contains the
- *   return value.
- * @param[in] obj
- *   Object address.
- * @param index
- *   Object index, unused.
- */
-static void
-txq_mp2mr_mbuf_check(struct rte_mempool *mp, void *arg, void *obj,
-	uint32_t index __rte_unused)
-{
-	struct txq_mp2mr_mbuf_check_data *data = arg;
-	struct rte_mbuf *buf = obj;
-
-	/*
-	 * Check whether mbuf structure fits element size and whether mempool
-	 * pointer is valid.
-	 */
-	if (sizeof(*buf) > mp->elt_size || buf->pool != mp)
-		data->ret = -1;
-}
-
-/**
- * Iterator function for rte_mempool_walk() to register existing mempools and
- * fill the MP to MR cache of a TX queue.
- *
- * @param[in] mp
- *   Memory Pool to register.
- * @param *arg
- *   Pointer to TX queue structure.
- */
-static void
-txq_mp2mr_iter(struct rte_mempool *mp, void *arg)
-{
-	struct txq *txq = arg;
-	struct txq_mp2mr_mbuf_check_data data = {
-		.ret = 0,
-	};
-
-	/* Register mempool only if the first element looks like a mbuf. */
-	if (rte_mempool_obj_iter(mp, txq_mp2mr_mbuf_check, &data) == 0 ||
-			data.ret == -1)
-		return;
-	mlx4_txq_mp2mr(txq, mp);
-}
-
-/**
- * Configure a TX queue.
- *
- * @param dev
- *   Pointer to Ethernet device structure.
- * @param txq
- *   Pointer to TX queue structure.
- * @param desc
- *   Number of descriptors to configure in queue.
- * @param socket
- *   NUMA socket on which memory must be allocated.
- * @param[in] conf
- *   Thresholds parameters.
- *
- * @return
- *   0 on success, negative errno value otherwise and rte_errno is set.
- */
-static int
-txq_setup(struct rte_eth_dev *dev, struct txq *txq, uint16_t desc,
-	  unsigned int socket, const struct rte_eth_txconf *conf)
-{
-	struct priv *priv = dev->data->dev_private;
-	struct txq tmpl = {
-		.priv = priv,
-		.socket = socket
-	};
-	union {
-		struct ibv_qp_init_attr init;
-		struct ibv_qp_attr mod;
-	} attr;
-	int ret;
-
-	(void)conf; /* Thresholds configuration (ignored). */
-	if (priv == NULL) {
-		rte_errno = EINVAL;
-		goto error;
-	}
-	if (desc == 0) {
-		rte_errno = EINVAL;
-		ERROR("%p: invalid number of Tx descriptors", (void *)dev);
-		goto error;
-	}
-	/* MRs will be registered in mp2mr[] later. */
-	tmpl.cq = ibv_create_cq(priv->ctx, desc, NULL, NULL, 0);
-	if (tmpl.cq == NULL) {
-		rte_errno = ENOMEM;
-		ERROR("%p: CQ creation failure: %s",
-		      (void *)dev, strerror(rte_errno));
-		goto error;
-	}
-	DEBUG("priv->device_attr.max_qp_wr is %d",
-	      priv->device_attr.max_qp_wr);
-	DEBUG("priv->device_attr.max_sge is %d",
-	      priv->device_attr.max_sge);
-	attr.init = (struct ibv_qp_init_attr){
-		/* CQ to be associated with the send queue. */
-		.send_cq = tmpl.cq,
-		/* CQ to be associated with the receive queue. */
-		.recv_cq = tmpl.cq,
-		.cap = {
-			/* Max number of outstanding WRs. */
-			.max_send_wr = ((priv->device_attr.max_qp_wr < desc) ?
-					priv->device_attr.max_qp_wr :
-					desc),
-			/* Max number of scatter/gather elements in a WR. */
-			.max_send_sge = 1,
-			.max_inline_data = MLX4_PMD_MAX_INLINE,
-		},
-		.qp_type = IBV_QPT_RAW_PACKET,
-		/*
-		 * Do *NOT* enable this, completions events are managed per
-		 * Tx burst.
-		 */
-		.sq_sig_all = 0,
-	};
-	tmpl.qp = ibv_create_qp(priv->pd, &attr.init);
-	if (tmpl.qp == NULL) {
-		rte_errno = errno ? errno : EINVAL;
-		ERROR("%p: QP creation failure: %s",
-		      (void *)dev, strerror(rte_errno));
-		goto error;
-	}
-	/* ibv_create_qp() updates this value. */
-	tmpl.max_inline = attr.init.cap.max_inline_data;
-	attr.mod = (struct ibv_qp_attr){
-		/* Move the QP to this state. */
-		.qp_state = IBV_QPS_INIT,
-		/* Primary port number. */
-		.port_num = priv->port
-	};
-	ret = ibv_modify_qp(tmpl.qp, &attr.mod, IBV_QP_STATE | IBV_QP_PORT);
-	if (ret) {
-		rte_errno = ret;
-		ERROR("%p: QP state to IBV_QPS_INIT failed: %s",
-		      (void *)dev, strerror(rte_errno));
-		goto error;
-	}
-	ret = txq_alloc_elts(&tmpl, desc);
-	if (ret) {
-		rte_errno = ret;
-		ERROR("%p: TXQ allocation failed: %s",
-		      (void *)dev, strerror(rte_errno));
-		goto error;
-	}
-	attr.mod = (struct ibv_qp_attr){
-		.qp_state = IBV_QPS_RTR
-	};
-	ret = ibv_modify_qp(tmpl.qp, &attr.mod, IBV_QP_STATE);
-	if (ret) {
-		rte_errno = ret;
-		ERROR("%p: QP state to IBV_QPS_RTR failed: %s",
-		      (void *)dev, strerror(rte_errno));
-		goto error;
-	}
-	attr.mod.qp_state = IBV_QPS_RTS;
-	ret = ibv_modify_qp(tmpl.qp, &attr.mod, IBV_QP_STATE);
-	if (ret) {
-		rte_errno = ret;
-		ERROR("%p: QP state to IBV_QPS_RTS failed: %s",
-		      (void *)dev, strerror(rte_errno));
-		goto error;
-	}
-	/* Clean up txq in case we're reinitializing it. */
-	DEBUG("%p: cleaning-up old txq just in case", (void *)txq);
-	txq_cleanup(txq);
-	*txq = tmpl;
-	DEBUG("%p: txq updated with %p", (void *)txq, (void *)&tmpl);
-	/* Pre-register known mempools. */
-	rte_mempool_walk(txq_mp2mr_iter, txq);
-	return 0;
-error:
-	ret = rte_errno;
-	txq_cleanup(&tmpl);
-	rte_errno = ret;
-	assert(rte_errno > 0);
-	return -rte_errno;
-}
-
-/**
- * DPDK callback to configure a TX queue.
- *
- * @param dev
- *   Pointer to Ethernet device structure.
- * @param idx
- *   TX queue index.
- * @param desc
- *   Number of descriptors to configure in queue.
- * @param socket
- *   NUMA socket on which memory must be allocated.
- * @param[in] conf
- *   Thresholds parameters.
- *
- * @return
- *   0 on success, negative errno value otherwise and rte_errno is set.
- */
-static int
-mlx4_tx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
-		    unsigned int socket, const struct rte_eth_txconf *conf)
-{
-	struct priv *priv = dev->data->dev_private;
-	struct txq *txq = (*priv->txqs)[idx];
-	int ret;
-
-	DEBUG("%p: configuring queue %u for %u descriptors",
-	      (void *)dev, idx, desc);
-	if (idx >= priv->txqs_n) {
-		rte_errno = EOVERFLOW;
-		ERROR("%p: queue index out of range (%u >= %u)",
-		      (void *)dev, idx, priv->txqs_n);
-		return -rte_errno;
-	}
-	if (txq != NULL) {
-		DEBUG("%p: reusing already allocated queue index %u (%p)",
-		      (void *)dev, idx, (void *)txq);
-		if (priv->started) {
-			rte_errno = EEXIST;
-			return -rte_errno;
-		}
-		(*priv->txqs)[idx] = NULL;
-		txq_cleanup(txq);
-	} else {
-		txq = rte_calloc_socket("TXQ", 1, sizeof(*txq), 0, socket);
-		if (txq == NULL) {
-			rte_errno = ENOMEM;
-			ERROR("%p: unable to allocate queue index %u",
-			      (void *)dev, idx);
-			return -rte_errno;
-		}
-	}
-	ret = txq_setup(dev, txq, desc, socket, conf);
-	if (ret)
-		rte_free(txq);
-	else {
-		txq->stats.idx = idx;
-		DEBUG("%p: adding TX queue %p to list",
-		      (void *)dev, (void *)txq);
-		(*priv->txqs)[idx] = txq;
-		/* Update send callback. */
-		dev->tx_pkt_burst = mlx4_tx_burst;
-	}
-	return ret;
-}
-
-/**
- * DPDK callback to release a TX queue.
- *
- * @param dpdk_txq
- *   Generic TX queue pointer.
- */
-static void
-mlx4_tx_queue_release(void *dpdk_txq)
-{
-	struct txq *txq = (struct txq *)dpdk_txq;
-	struct priv *priv;
-	unsigned int i;
-
-	if (txq == NULL)
-		return;
-	priv = txq->priv;
-	for (i = 0; (i != priv->txqs_n); ++i)
-		if ((*priv->txqs)[i] == txq) {
-			DEBUG("%p: removing TX queue %p from list",
-			      (void *)priv->dev, (void *)txq);
-			(*priv->txqs)[i] = NULL;
-			break;
-		}
-	txq_cleanup(txq);
-	rte_free(txq);
-}
-
 /* RX queues handling. */
 
 /**
@@ -1288,7 +869,7 @@ mlx4_dev_close(struct rte_eth_dev *dev)
 			if (tmp == NULL)
 				continue;
 			(*priv->txqs)[i] = NULL;
-			txq_cleanup(tmp);
+			mlx4_txq_cleanup(tmp);
 			rte_free(tmp);
 		}
 		priv->txqs_n = 0;
diff --git a/drivers/net/mlx4/mlx4_rxtx.h b/drivers/net/mlx4/mlx4_rxtx.h
index 669c8a4..1b457a5 100644
--- a/drivers/net/mlx4/mlx4_rxtx.h
+++ b/drivers/net/mlx4/mlx4_rxtx.h
@@ -45,6 +45,7 @@
 #pragma GCC diagnostic error "-Wpedantic"
 #endif
 
+#include <rte_ethdev.h>
 #include <rte_mbuf.h>
 #include <rte_mempool.h>
 
@@ -131,4 +132,12 @@ uint16_t mlx4_tx_burst_removed(void *dpdk_txq, struct rte_mbuf **pkts,
 uint16_t mlx4_rx_burst_removed(void *dpdk_rxq, struct rte_mbuf **pkts,
 			       uint16_t pkts_n);
 
+/* mlx4_txq.c */
+
+void mlx4_txq_cleanup(struct txq *txq);
+int mlx4_tx_queue_setup(struct rte_eth_dev *dev, uint16_t idx,
+			uint16_t desc, unsigned int socket,
+			const struct rte_eth_txconf *conf);
+void mlx4_tx_queue_release(void *dpdk_txq);
+
 #endif /* MLX4_RXTX_H_ */
diff --git a/drivers/net/mlx4/mlx4_txq.c b/drivers/net/mlx4/mlx4_txq.c
new file mode 100644
index 0000000..945833b
--- /dev/null
+++ b/drivers/net/mlx4/mlx4_txq.c
@@ -0,0 +1,472 @@
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright 2017 6WIND S.A.
+ *   Copyright 2017 Mellanox
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of 6WIND S.A. nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * @file
+ * Tx queues configuration for mlx4 driver.
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+/* Verbs headers do not support -pedantic. */
+#ifdef PEDANTIC
+#pragma GCC diagnostic ignored "-Wpedantic"
+#endif
+#include <infiniband/verbs.h>
+#ifdef PEDANTIC
+#pragma GCC diagnostic error "-Wpedantic"
+#endif
+
+#include <rte_common.h>
+#include <rte_errno.h>
+#include <rte_ethdev.h>
+#include <rte_malloc.h>
+#include <rte_mbuf.h>
+#include <rte_mempool.h>
+
+#include "mlx4.h"
+#include "mlx4_autoconf.h"
+#include "mlx4_rxtx.h"
+#include "mlx4_utils.h"
+
+/**
+ * Allocate Tx queue elements.
+ *
+ * @param txq
+ *   Pointer to Tx queue structure.
+ * @param elts_n
+ *   Number of elements to allocate.
+ *
+ * @return
+ *   0 on success, negative errno value otherwise and rte_errno is set.
+ */
+static int
+mlx4_txq_alloc_elts(struct txq *txq, unsigned int elts_n)
+{
+	unsigned int i;
+	struct txq_elt (*elts)[elts_n] =
+		rte_calloc_socket("TXQ", 1, sizeof(*elts), 0, txq->socket);
+	int ret = 0;
+
+	if (elts == NULL) {
+		ERROR("%p: can't allocate packets array", (void *)txq);
+		ret = ENOMEM;
+		goto error;
+	}
+	for (i = 0; (i != elts_n); ++i) {
+		struct txq_elt *elt = &(*elts)[i];
+
+		elt->buf = NULL;
+	}
+	DEBUG("%p: allocated and configured %u WRs", (void *)txq, elts_n);
+	txq->elts_n = elts_n;
+	txq->elts = elts;
+	txq->elts_head = 0;
+	txq->elts_tail = 0;
+	txq->elts_comp = 0;
+	/*
+	 * Request send completion every MLX4_PMD_TX_PER_COMP_REQ packets or
+	 * at least 4 times per ring.
+	 */
+	txq->elts_comp_cd_init =
+		((MLX4_PMD_TX_PER_COMP_REQ < (elts_n / 4)) ?
+		 MLX4_PMD_TX_PER_COMP_REQ : (elts_n / 4));
+	txq->elts_comp_cd = txq->elts_comp_cd_init;
+	assert(ret == 0);
+	return 0;
+error:
+	rte_free(elts);
+	DEBUG("%p: failed, freed everything", (void *)txq);
+	assert(ret > 0);
+	rte_errno = ret;
+	return -rte_errno;
+}
+
+/**
+ * Free Tx queue elements.
+ *
+ * @param txq
+ *   Pointer to Tx queue structure.
+ */
+static void
+mlx4_txq_free_elts(struct txq *txq)
+{
+	unsigned int elts_n = txq->elts_n;
+	unsigned int elts_head = txq->elts_head;
+	unsigned int elts_tail = txq->elts_tail;
+	struct txq_elt (*elts)[elts_n] = txq->elts;
+
+	DEBUG("%p: freeing WRs", (void *)txq);
+	txq->elts_n = 0;
+	txq->elts_head = 0;
+	txq->elts_tail = 0;
+	txq->elts_comp = 0;
+	txq->elts_comp_cd = 0;
+	txq->elts_comp_cd_init = 0;
+	txq->elts = NULL;
+	if (elts == NULL)
+		return;
+	while (elts_tail != elts_head) {
+		struct txq_elt *elt = &(*elts)[elts_tail];
+
+		assert(elt->buf != NULL);
+		rte_pktmbuf_free(elt->buf);
+#ifndef NDEBUG
+		/* Poisoning. */
+		memset(elt, 0x77, sizeof(*elt));
+#endif
+		if (++elts_tail == elts_n)
+			elts_tail = 0;
+	}
+	rte_free(elts);
+}
+
+/**
+ * Clean up a Tx queue.
+ *
+ * Destroy objects, free allocated memory and reset the structure for reuse.
+ *
+ * @param txq
+ *   Pointer to Tx queue structure.
+ */
+void
+mlx4_txq_cleanup(struct txq *txq)
+{
+	size_t i;
+
+	DEBUG("cleaning up %p", (void *)txq);
+	mlx4_txq_free_elts(txq);
+	if (txq->qp != NULL)
+		claim_zero(ibv_destroy_qp(txq->qp));
+	if (txq->cq != NULL)
+		claim_zero(ibv_destroy_cq(txq->cq));
+	for (i = 0; (i != RTE_DIM(txq->mp2mr)); ++i) {
+		if (txq->mp2mr[i].mp == NULL)
+			break;
+		assert(txq->mp2mr[i].mr != NULL);
+		claim_zero(ibv_dereg_mr(txq->mp2mr[i].mr));
+	}
+	memset(txq, 0, sizeof(*txq));
+}
+
+struct txq_mp2mr_mbuf_check_data {
+	int ret;
+};
+
+/**
+ * Callback function for rte_mempool_obj_iter() to check whether a given
+ * mempool object looks like a mbuf.
+ *
+ * @param[in] mp
+ *   The mempool pointer
+ * @param[in] arg
+ *   Context data (struct mlx4_txq_mp2mr_mbuf_check_data). Contains the
+ *   return value.
+ * @param[in] obj
+ *   Object address.
+ * @param index
+ *   Object index, unused.
+ */
+static void
+mlx4_txq_mp2mr_mbuf_check(struct rte_mempool *mp, void *arg, void *obj,
+			  uint32_t index)
+{
+	struct txq_mp2mr_mbuf_check_data *data = arg;
+	struct rte_mbuf *buf = obj;
+
+	(void)index;
+	/*
+	 * Check whether mbuf structure fits element size and whether mempool
+	 * pointer is valid.
+	 */
+	if (sizeof(*buf) > mp->elt_size || buf->pool != mp)
+		data->ret = -1;
+}
+
+/**
+ * Iterator function for rte_mempool_walk() to register existing mempools and
+ * fill the MP to MR cache of a Tx queue.
+ *
+ * @param[in] mp
+ *   Memory Pool to register.
+ * @param *arg
+ *   Pointer to Tx queue structure.
+ */
+static void
+mlx4_txq_mp2mr_iter(struct rte_mempool *mp, void *arg)
+{
+	struct txq *txq = arg;
+	struct txq_mp2mr_mbuf_check_data data = {
+		.ret = 0,
+	};
+
+	/* Register mempool only if the first element looks like a mbuf. */
+	if (rte_mempool_obj_iter(mp, mlx4_txq_mp2mr_mbuf_check, &data) == 0 ||
+			data.ret == -1)
+		return;
+	mlx4_txq_mp2mr(txq, mp);
+}
+
+/**
+ * Configure a Tx queue.
+ *
+ * @param dev
+ *   Pointer to Ethernet device structure.
+ * @param txq
+ *   Pointer to Tx queue structure.
+ * @param desc
+ *   Number of descriptors to configure in queue.
+ * @param socket
+ *   NUMA socket on which memory must be allocated.
+ * @param[in] conf
+ *   Thresholds parameters.
+ *
+ * @return
+ *   0 on success, negative errno value otherwise and rte_errno is set.
+ */
+static int
+mlx4_txq_setup(struct rte_eth_dev *dev, struct txq *txq, uint16_t desc,
+	       unsigned int socket, const struct rte_eth_txconf *conf)
+{
+	struct priv *priv = dev->data->dev_private;
+	struct txq tmpl = {
+		.priv = priv,
+		.socket = socket
+	};
+	union {
+		struct ibv_qp_init_attr init;
+		struct ibv_qp_attr mod;
+	} attr;
+	int ret;
+
+	(void)conf; /* Thresholds configuration (ignored). */
+	if (priv == NULL) {
+		rte_errno = EINVAL;
+		goto error;
+	}
+	if (desc == 0) {
+		rte_errno = EINVAL;
+		ERROR("%p: invalid number of Tx descriptors", (void *)dev);
+		goto error;
+	}
+	/* MRs will be registered in mp2mr[] later. */
+	tmpl.cq = ibv_create_cq(priv->ctx, desc, NULL, NULL, 0);
+	if (tmpl.cq == NULL) {
+		rte_errno = ENOMEM;
+		ERROR("%p: CQ creation failure: %s",
+		      (void *)dev, strerror(rte_errno));
+		goto error;
+	}
+	DEBUG("priv->device_attr.max_qp_wr is %d",
+	      priv->device_attr.max_qp_wr);
+	DEBUG("priv->device_attr.max_sge is %d",
+	      priv->device_attr.max_sge);
+	attr.init = (struct ibv_qp_init_attr){
+		/* CQ to be associated with the send queue. */
+		.send_cq = tmpl.cq,
+		/* CQ to be associated with the receive queue. */
+		.recv_cq = tmpl.cq,
+		.cap = {
+			/* Max number of outstanding WRs. */
+			.max_send_wr = ((priv->device_attr.max_qp_wr < desc) ?
+					priv->device_attr.max_qp_wr :
+					desc),
+			/* Max number of scatter/gather elements in a WR. */
+			.max_send_sge = 1,
+			.max_inline_data = MLX4_PMD_MAX_INLINE,
+		},
+		.qp_type = IBV_QPT_RAW_PACKET,
+		/*
+		 * Do *NOT* enable this, completions events are managed per
+		 * Tx burst.
+		 */
+		.sq_sig_all = 0,
+	};
+	tmpl.qp = ibv_create_qp(priv->pd, &attr.init);
+	if (tmpl.qp == NULL) {
+		rte_errno = errno ? errno : EINVAL;
+		ERROR("%p: QP creation failure: %s",
+		      (void *)dev, strerror(rte_errno));
+		goto error;
+	}
+	/* ibv_create_qp() updates this value. */
+	tmpl.max_inline = attr.init.cap.max_inline_data;
+	attr.mod = (struct ibv_qp_attr){
+		/* Move the QP to this state. */
+		.qp_state = IBV_QPS_INIT,
+		/* Primary port number. */
+		.port_num = priv->port
+	};
+	ret = ibv_modify_qp(tmpl.qp, &attr.mod, IBV_QP_STATE | IBV_QP_PORT);
+	if (ret) {
+		rte_errno = ret;
+		ERROR("%p: QP state to IBV_QPS_INIT failed: %s",
+		      (void *)dev, strerror(rte_errno));
+		goto error;
+	}
+	ret = mlx4_txq_alloc_elts(&tmpl, desc);
+	if (ret) {
+		rte_errno = ret;
+		ERROR("%p: TXQ allocation failed: %s",
+		      (void *)dev, strerror(rte_errno));
+		goto error;
+	}
+	attr.mod = (struct ibv_qp_attr){
+		.qp_state = IBV_QPS_RTR
+	};
+	ret = ibv_modify_qp(tmpl.qp, &attr.mod, IBV_QP_STATE);
+	if (ret) {
+		rte_errno = ret;
+		ERROR("%p: QP state to IBV_QPS_RTR failed: %s",
+		      (void *)dev, strerror(rte_errno));
+		goto error;
+	}
+	attr.mod.qp_state = IBV_QPS_RTS;
+	ret = ibv_modify_qp(tmpl.qp, &attr.mod, IBV_QP_STATE);
+	if (ret) {
+		rte_errno = ret;
+		ERROR("%p: QP state to IBV_QPS_RTS failed: %s",
+		      (void *)dev, strerror(rte_errno));
+		goto error;
+	}
+	/* Clean up txq in case we're reinitializing it. */
+	DEBUG("%p: cleaning-up old txq just in case", (void *)txq);
+	mlx4_txq_cleanup(txq);
+	*txq = tmpl;
+	DEBUG("%p: txq updated with %p", (void *)txq, (void *)&tmpl);
+	/* Pre-register known mempools. */
+	rte_mempool_walk(mlx4_txq_mp2mr_iter, txq);
+	return 0;
+error:
+	ret = rte_errno;
+	mlx4_txq_cleanup(&tmpl);
+	rte_errno = ret;
+	assert(rte_errno > 0);
+	return -rte_errno;
+}
+
+/**
+ * DPDK callback to configure a Tx queue.
+ *
+ * @param dev
+ *   Pointer to Ethernet device structure.
+ * @param idx
+ *   Tx queue index.
+ * @param desc
+ *   Number of descriptors to configure in queue.
+ * @param socket
+ *   NUMA socket on which memory must be allocated.
+ * @param[in] conf
+ *   Thresholds parameters.
+ *
+ * @return
+ *   0 on success, negative errno value otherwise and rte_errno is set.
+ */
+int
+mlx4_tx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
+		    unsigned int socket, const struct rte_eth_txconf *conf)
+{
+	struct priv *priv = dev->data->dev_private;
+	struct txq *txq = (*priv->txqs)[idx];
+	int ret;
+
+	DEBUG("%p: configuring queue %u for %u descriptors",
+	      (void *)dev, idx, desc);
+	if (idx >= priv->txqs_n) {
+		rte_errno = EOVERFLOW;
+		ERROR("%p: queue index out of range (%u >= %u)",
+		      (void *)dev, idx, priv->txqs_n);
+		return -rte_errno;
+	}
+	if (txq != NULL) {
+		DEBUG("%p: reusing already allocated queue index %u (%p)",
+		      (void *)dev, idx, (void *)txq);
+		if (priv->started) {
+			rte_errno = EEXIST;
+			return -rte_errno;
+		}
+		(*priv->txqs)[idx] = NULL;
+		mlx4_txq_cleanup(txq);
+	} else {
+		txq = rte_calloc_socket("TXQ", 1, sizeof(*txq), 0, socket);
+		if (txq == NULL) {
+			rte_errno = ENOMEM;
+			ERROR("%p: unable to allocate queue index %u",
+			      (void *)dev, idx);
+			return -rte_errno;
+		}
+	}
+	ret = mlx4_txq_setup(dev, txq, desc, socket, conf);
+	if (ret) {
+		rte_free(txq);
+	} else {
+		txq->stats.idx = idx;
+		DEBUG("%p: adding Tx queue %p to list",
+		      (void *)dev, (void *)txq);
+		(*priv->txqs)[idx] = txq;
+		/* Update send callback. */
+		dev->tx_pkt_burst = mlx4_tx_burst;
+	}
+	return ret;
+}
+
+/**
+ * DPDK callback to release a Tx queue.
+ *
+ * @param dpdk_txq
+ *   Generic Tx queue pointer.
+ */
+void
+mlx4_tx_queue_release(void *dpdk_txq)
+{
+	struct txq *txq = (struct txq *)dpdk_txq;
+	struct priv *priv;
+	unsigned int i;
+
+	if (txq == NULL)
+		return;
+	priv = txq->priv;
+	for (i = 0; (i != priv->txqs_n); ++i)
+		if ((*priv->txqs)[i] == txq) {
+			DEBUG("%p: removing Tx queue %p from list",
+			      (void *)priv->dev, (void *)txq);
+			(*priv->txqs)[i] = NULL;
+			break;
+		}
+	mlx4_txq_cleanup(txq);
+	rte_free(txq);
+}
-- 
2.1.4