diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index 768cb9e5a..bc4691cba 100644
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -108,7 +108,7 @@ mlx5_getenv_int(const char *name)
  *   A pointer to the callback data.
  *
  * @return
- *   a pointer to the allocate space.
+ *   Allocated buffer, NULL otherwise and rte_errno is set.
  */
 static void *
 mlx5_alloc_verbs_buf(size_t size, void *data)
@@ -130,6 +130,8 @@ mlx5_alloc_verbs_buf(size_t size, void *data)
 	}
 	assert(data != NULL);
 	ret = rte_malloc_socket(__func__, size, alignment, socket);
+	if (!ret && size)
+		rte_errno = ENOMEM;
 	DEBUG("Extern alloc size: %lu, align: %lu: %p", size, alignment, ret);
 	return ret;
 }
@@ -365,7 +367,7 @@ mlx5_dev_idx(struct rte_pci_addr *pci_addr)
  *   User data.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_args_check(const char *key, const char *val, void *opaque)
@@ -376,8 +378,9 @@ mlx5_args_check(const char *key, const char *val, void *opaque)
 	errno = 0;
 	tmp = strtoul(val, NULL, 0);
 	if (errno) {
+		rte_errno = errno;
 		WARN("%s: \"%s\" is not a valid integer", key, val);
-		return errno;
+		return -rte_errno;
 	}
 	if (strcmp(MLX5_RXQ_CQE_COMP_EN, key) == 0) {
 		config->cqe_comp = !!tmp;
@@ -397,7 +400,8 @@ mlx5_args_check(const char *key, const char *val, void *opaque)
 		config->rx_vec_en = !!tmp;
 	} else {
 		WARN("%s: unknown parameter", key);
-		return -EINVAL;
+		rte_errno = EINVAL;
+		return -rte_errno;
 	}
 	return 0;
 }
@@ -411,7 +415,7 @@ mlx5_args_check(const char *key, const char *val, void *opaque)
  *   Device arguments structure.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_args(struct mlx5_dev_config *config, struct rte_devargs *devargs)
@@ -442,9 +446,10 @@ mlx5_args(struct mlx5_dev_config *config, struct rte_devargs *devargs)
 		if (rte_kvargs_count(kvlist, params[i])) {
 			ret = rte_kvargs_process(kvlist, params[i],
 						 mlx5_args_check, config);
-			if (ret != 0) {
+			if (ret) {
+				rte_errno = EINVAL;
 				rte_kvargs_free(kvlist);
-				return ret;
+				return -rte_errno;
 			}
 		}
 	}
@@ -470,7 +475,7 @@ static void *uar_base;
  *   Pointer to Ethernet device.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_uar_init_primary(struct rte_eth_dev *dev)
@@ -479,7 +484,6 @@ mlx5_uar_init_primary(struct rte_eth_dev *dev)
 	void *addr = (void *)0;
 	int i;
 	const struct rte_mem_config *mcfg;
-	int ret;
 
 	if (uar_base) { /* UAR address space mapped. */
 		priv->uar_base = uar_base;
@@ -501,8 +505,8 @@ mlx5_uar_init_primary(struct rte_eth_dev *dev)
 	if (addr == MAP_FAILED) {
 		ERROR("Failed to reserve UAR address space, please adjust "
 		      "MLX5_UAR_SIZE or try --base-virtaddr");
-		ret = ENOMEM;
-		return ret;
+		rte_errno = ENOMEM;
+		return -rte_errno;
 	}
 	/* Accept either same addr or a new addr returned from mmap if target
 	 * range occupied.
@@ -521,14 +525,13 @@ mlx5_uar_init_primary(struct rte_eth_dev *dev)
  *   Pointer to Ethernet device.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_uar_init_secondary(struct rte_eth_dev *dev)
 {
 	struct priv *priv = dev->data->dev_private;
 	void *addr;
-	int ret;
 
 	assert(priv->uar_base);
 	if (uar_base) { /* already reserved. */
@@ -541,15 +544,15 @@ mlx5_uar_init_secondary(struct rte_eth_dev *dev)
 	if (addr == MAP_FAILED) {
 		ERROR("UAR mmap failed: %p size: %llu",
 		      priv->uar_base, MLX5_UAR_SIZE);
-		ret = ENXIO;
-		return ret;
+		rte_errno = ENXIO;
+		return -rte_errno;
 	}
 	if (priv->uar_base != addr) {
 		ERROR("UAR address %p size %llu occupied, please adjust "
 		      "MLX5_UAR_OFFSET or try EAL parameter --base-virtaddr",
 		      priv->uar_base, MLX5_UAR_SIZE);
-		ret = ENXIO;
-		return ret;
+		rte_errno = ENXIO;
+		return -rte_errno;
 	}
 	uar_base = addr; /* process local, don't reserve again */
 	INFO("Reserved UAR address space: %p", addr);
@@ -568,13 +571,13 @@ mlx5_uar_init_secondary(struct rte_eth_dev *dev)
  *   PCI device information.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 	       struct rte_pci_device *pci_dev)
 {
-	struct ibv_device **list;
+	struct ibv_device **list = NULL;
 	struct ibv_device *ibv_dev;
 	int err = 0;
 	struct ibv_context *attr_ctx = NULL;
@@ -594,7 +597,8 @@ mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 	idx = mlx5_dev_idx(&pci_dev->addr);
 	if (idx == -1) {
 		ERROR("this driver cannot support any more adapters");
-		return -ENOMEM;
+		err = ENOMEM;
+		goto error;
 	}
 	DEBUG("using driver device index %d", idx);
 	/* Save PCI address. */
@@ -602,9 +606,10 @@ mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 	list = mlx5_glue->get_device_list(&i);
 	if (list == NULL) {
 		assert(errno);
+		err = errno;
 		if (errno == ENOSYS)
 			ERROR("cannot list devices, is ib_uverbs loaded?");
-		return -errno;
+		goto error;
 	}
 	assert(i >= 0);
 	/*
@@ -626,7 +631,8 @@ mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 		INFO("PCI information matches, using device \"%s\"",
 		     list[i]->name);
 		attr_ctx = mlx5_glue->open_device(list[i]);
-		err = errno;
+		rte_errno = errno;
+		err = rte_errno;
 		break;
 	}
 	if (attr_ctx == NULL) {
@@ -634,13 +640,12 @@ mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 		switch (err) {
 		case 0:
 			ERROR("cannot access device, is mlx5_ib loaded?");
-			return -ENODEV;
+			err = ENODEV;
+			goto error;
 		case EINVAL:
 			ERROR("cannot use device, are drivers up to date?");
-			return -EINVAL;
+			goto error;
 		}
-		assert(err > 0);
-		return -err;
 	}
 	ibv_dev = list[i];
 	DEBUG("device opened");
@@ -680,8 +685,10 @@ mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 #else
 	WARN("Tunnel offloading disabled due to old OFED/rdma-core version");
 #endif
-	if (mlx5_glue->query_device_ex(attr_ctx, NULL, &device_attr))
+	if (mlx5_glue->query_device_ex(attr_ctx, NULL, &device_attr)) {
+		err = errno;
 		goto error;
+	}
 	INFO("%u port(s) detected", device_attr.orig_attr.phys_port_cnt);
 	for (i = 0; i < device_attr.orig_attr.phys_port_cnt; i++) {
 		char name[RTE_ETH_NAME_MAX_LEN];
@@ -718,22 +725,19 @@ mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 			eth_dev = rte_eth_dev_attach_secondary(name);
 			if (eth_dev == NULL) {
 				ERROR("can not attach rte ethdev");
-				err = ENOMEM;
+				rte_errno = ENOMEM;
+				err = rte_errno;
 				goto error;
 			}
 			eth_dev->device = &pci_dev->device;
 			eth_dev->dev_ops = &mlx5_dev_sec_ops;
 			err = mlx5_uar_init_secondary(eth_dev);
-			if (err < 0) {
-				err = -err;
+			if (err)
 				goto error;
-			}
 			/* Receive command fd from primary process */
 			err = mlx5_socket_connect(eth_dev);
-			if (err < 0) {
-				err = -err;
+			if (err)
 				goto error;
-			}
 			/* Remap UAR for Tx queues. */
 			err = mlx5_tx_uar_remap(eth_dev, err);
 			if (err)
@@ -804,6 +808,7 @@ mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 		}
 		if (mlx5_glue->query_device_ex(ctx, NULL, &device_attr_ex)) {
 			ERROR("ibv_query_device_ex() failed");
+			err = errno;
 			goto port_error;
 		}
 
@@ -901,7 +906,9 @@ mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 		}
 #endif
 		/* Get actual MTU if possible. */
-		mlx5_get_mtu(eth_dev, &priv->mtu);
+		err = mlx5_get_mtu(eth_dev, &priv->mtu);
+		if (err)
+			goto port_error;
 		DEBUG("port %u MTU is %u", priv->port, priv->mtu);
 		/*
 		 * Initialize burst functions to prevent crashes before link-up.
@@ -945,16 +952,19 @@ mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 	 */
 	/* no port found, complain */
 	if (!mlx5_dev[idx].ports) {
-		err = ENODEV;
-		goto error;
+		rte_errno = ENODEV;
+		err = rte_errno;
 	}
 error:
 	if (attr_ctx)
 		claim_zero(mlx5_glue->close_device(attr_ctx));
 	if (list)
 		mlx5_glue->free_device_list(list);
-	assert(err >= 0);
-	return -err;
+	if (err) {
+		rte_errno = err;
+		return -rte_errno;
+	}
+	return 0;
 }
 
 static const struct rte_pci_id mlx5_pci_id_map[] = {
diff --git a/drivers/net/mlx5/mlx5_ethdev.c b/drivers/net/mlx5/mlx5_ethdev.c
index 1fde3d842..d7e85577f 100644
--- a/drivers/net/mlx5/mlx5_ethdev.c
+++ b/drivers/net/mlx5/mlx5_ethdev.c
@@ -101,7 +101,7 @@ struct ethtool_link_settings {
  *   Interface name output buffer.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_get_ifname(const struct rte_eth_dev *dev, char (*ifname)[IF_NAMESIZE])
@@ -117,8 +117,10 @@ mlx5_get_ifname(const struct rte_eth_dev *dev, char (*ifname)[IF_NAMESIZE])
 		MKSTR(path, "%s/device/net", priv->ibdev_path);
 
 		dir = opendir(path);
-		if (dir == NULL)
-			return -1;
+		if (dir == NULL) {
+			rte_errno = errno;
+			return -rte_errno;
+		}
 	}
 	while ((dent = readdir(dir)) != NULL) {
 		char *name = dent->d_name;
@@ -168,8 +170,10 @@ mlx5_get_ifname(const struct rte_eth_dev *dev, char (*ifname)[IF_NAMESIZE])
 			snprintf(match, sizeof(match), "%s", name);
 	}
 	closedir(dir);
-	if (match[0] == '\0')
-		return -1;
+	if (match[0] == '\0') {
+		rte_errno = ENOENT;
+		return -rte_errno;
+	}
 	strncpy(*ifname, match, sizeof(*ifname));
 	return 0;
 }
@@ -185,20 +189,31 @@ mlx5_get_ifname(const struct rte_eth_dev *dev, char (*ifname)[IF_NAMESIZE])
  *   Interface request structure output buffer.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_ifreq(const struct rte_eth_dev *dev, int req, struct ifreq *ifr)
 {
 	int sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
-	int ret = -1;
+	int ret = 0;
 
-	if (sock == -1)
-		return ret;
-	if (mlx5_get_ifname(dev, &ifr->ifr_name) == 0)
-		ret = ioctl(sock, req, ifr);
+	if (sock == -1) {
+		rte_errno = errno;
+		return -rte_errno;
+	}
+	ret = mlx5_get_ifname(dev, &ifr->ifr_name);
+	if (ret)
+		goto error;
+	ret = ioctl(sock, req, ifr);
+	if (ret == -1) {
+		rte_errno = errno;
+		goto error;
+	}
 	close(sock);
-	return ret;
+	return 0;
+error:
+	close(sock);
+	return -rte_errno;
 }
 
 /**
@@ -210,7 +225,7 @@ mlx5_ifreq(const struct rte_eth_dev *dev, int req, struct ifreq *ifr)
  *   MTU value output buffer.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_get_mtu(struct rte_eth_dev *dev, uint16_t *mtu)
@@ -233,7 +248,7 @@ mlx5_get_mtu(struct rte_eth_dev *dev, uint16_t *mtu)
  *   MTU value to set.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_set_mtu(struct rte_eth_dev *dev, uint16_t mtu)
@@ -254,7 +269,7 @@ mlx5_set_mtu(struct rte_eth_dev *dev, uint16_t mtu)
  *   Bitmask for flags to modify.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_set_flags(struct rte_eth_dev *dev, unsigned int keep, unsigned int flags)
@@ -276,7 +291,7 @@ mlx5_set_flags(struct rte_eth_dev *dev, unsigned int keep, unsigned int flags)
  *   Pointer to Ethernet device structure.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_dev_configure(struct rte_eth_dev *dev)
@@ -295,31 +310,36 @@ mlx5_dev_configure(struct rte_eth_dev *dev)
 		(mlx5_get_rx_port_offloads() |
 		 mlx5_get_rx_queue_offloads(dev));
 	uint64_t rx_offloads = dev->data->dev_conf.rxmode.offloads;
+	int ret = 0;
 
 	if ((tx_offloads & supp_tx_offloads) != tx_offloads) {
 		ERROR("Some Tx offloads are not supported "
 		      "requested 0x%" PRIx64 " supported 0x%" PRIx64,
 		      tx_offloads, supp_tx_offloads);
-		return ENOTSUP;
+		rte_errno = ENOTSUP;
+		return -rte_errno;
 	}
 	if ((rx_offloads & supp_rx_offloads) != rx_offloads) {
 		ERROR("Some Rx offloads are not supported "
 		      "requested 0x%" PRIx64 " supported 0x%" PRIx64,
 		      rx_offloads, supp_rx_offloads);
-		return ENOTSUP;
+		rte_errno = ENOTSUP;
+		return -rte_errno;
 	}
 	if (use_app_rss_key &&
 	    (dev->data->dev_conf.rx_adv_conf.rss_conf.rss_key_len !=
 	     rss_hash_default_key_len)) {
 		/* MLX5 RSS only support 40bytes key. */
-		return EINVAL;
+		rte_errno = EINVAL;
+		return -rte_errno;
 	}
 	priv->rss_conf.rss_key =
 		rte_realloc(priv->rss_conf.rss_key,
 			    rss_hash_default_key_len, 0);
 	if (!priv->rss_conf.rss_key) {
 		ERROR("cannot allocate RSS hash key memory (%u)", rxqs_n);
-		return ENOMEM;
+		rte_errno = ENOMEM;
+		return -rte_errno;
 	}
 	memcpy(priv->rss_conf.rss_key,
 	       use_app_rss_key ?
@@ -337,7 +357,8 @@ mlx5_dev_configure(struct rte_eth_dev *dev)
 	}
 	if (rxqs_n > priv->config.ind_table_max_size) {
 		ERROR("cannot handle this many RX queues (%u)", rxqs_n);
-		return EINVAL;
+		rte_errno = EINVAL;
+		return -rte_errno;
 	}
 	if (rxqs_n == priv->rxqs_n)
 		return 0;
@@ -350,8 +371,9 @@ mlx5_dev_configure(struct rte_eth_dev *dev)
 	reta_idx_n = (1 << log2above((rxqs_n & (rxqs_n - 1)) ?
 				     priv->config.ind_table_max_size :
 				     rxqs_n));
-	if (mlx5_rss_reta_index_resize(dev, reta_idx_n))
-		return ENOMEM;
+	ret = mlx5_rss_reta_index_resize(dev, reta_idx_n);
+	if (ret)
+		return ret;
 	/* When the number of RX queues is not a power of two, the remaining
 	 * table entries are padded with reused WQs and hashes are not spread
 	 * uniformly. */
@@ -361,7 +383,6 @@ mlx5_dev_configure(struct rte_eth_dev *dev)
 			j = 0;
 	}
 	return 0;
-
 }
 
 /**
@@ -452,7 +473,7 @@ mlx5_dev_supported_ptypes_get(struct rte_eth_dev *dev)
  *   Pointer to Ethernet device structure.
  *
  * @return
- *   0 on success, -1 on error.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_link_update_unlocked_gset(struct rte_eth_dev *dev)
@@ -464,19 +485,22 @@ mlx5_link_update_unlocked_gset(struct rte_eth_dev *dev)
 	struct ifreq ifr;
 	struct rte_eth_link dev_link;
 	int link_speed = 0;
+	int ret;
 
-	if (mlx5_ifreq(dev, SIOCGIFFLAGS, &ifr)) {
-		WARN("ioctl(SIOCGIFFLAGS) failed: %s", strerror(errno));
-		return -1;
+	ret = mlx5_ifreq(dev, SIOCGIFFLAGS, &ifr);
+	if (ret) {
+		WARN("ioctl(SIOCGIFFLAGS) failed: %s", strerror(rte_errno));
+		return ret;
 	}
 	memset(&dev_link, 0, sizeof(dev_link));
 	dev_link.link_status = ((ifr.ifr_flags & IFF_UP) &&
 				(ifr.ifr_flags & IFF_RUNNING));
 	ifr.ifr_data = (void *)&edata;
-	if (mlx5_ifreq(dev, SIOCETHTOOL, &ifr)) {
+	ret = mlx5_ifreq(dev, SIOCETHTOOL, &ifr);
+	if (ret) {
 		WARN("ioctl(SIOCETHTOOL, ETHTOOL_GSET) failed: %s",
-		     strerror(errno));
-		return -1;
+		     strerror(rte_errno));
+		return ret;
 	}
 	link_speed = ethtool_cmd_speed(&edata);
 	if (link_speed == -1)
@@ -506,7 +530,8 @@ mlx5_link_update_unlocked_gset(struct rte_eth_dev *dev)
 		return 0;
 	}
 	/* Link status is still the same. */
-	return -1;
+	rte_errno = EAGAIN;
+	return -rte_errno;
 }
 
 /**
@@ -516,7 +541,7 @@ mlx5_link_update_unlocked_gset(struct rte_eth_dev *dev)
  *   Pointer to Ethernet device structure.
  *
  * @return
- *   0 on success, -1 on error.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_link_update_unlocked_gs(struct rte_eth_dev *dev)
@@ -526,19 +551,22 @@ mlx5_link_update_unlocked_gs(struct rte_eth_dev *dev)
 	struct ifreq ifr;
 	struct rte_eth_link dev_link;
 	uint64_t sc;
+	int ret;
 
-	if (mlx5_ifreq(dev, SIOCGIFFLAGS, &ifr)) {
-		WARN("ioctl(SIOCGIFFLAGS) failed: %s", strerror(errno));
-		return -1;
+	ret = mlx5_ifreq(dev, SIOCGIFFLAGS, &ifr);
+	if (ret) {
+		WARN("ioctl(SIOCGIFFLAGS) failed: %s", strerror(rte_errno));
+		return ret;
 	}
 	memset(&dev_link, 0, sizeof(dev_link));
 	dev_link.link_status = ((ifr.ifr_flags & IFF_UP) &&
 				(ifr.ifr_flags & IFF_RUNNING));
 	ifr.ifr_data = (void *)&gcmd;
-	if (mlx5_ifreq(dev, SIOCETHTOOL, &ifr)) {
+	ret = mlx5_ifreq(dev, SIOCETHTOOL, &ifr);
+	if (ret) {
 		DEBUG("ioctl(SIOCETHTOOL, ETHTOOL_GLINKSETTINGS) failed: %s",
-		      strerror(errno));
-		return -1;
+		      strerror(rte_errno));
+		return ret;
 	}
 	gcmd.link_mode_masks_nwords = -gcmd.link_mode_masks_nwords;
 
@@ -549,10 +577,11 @@ mlx5_link_update_unlocked_gs(struct rte_eth_dev *dev)
 
 	*ecmd = gcmd;
 	ifr.ifr_data = (void *)ecmd;
-	if (mlx5_ifreq(dev, SIOCETHTOOL, &ifr)) {
+	ret = mlx5_ifreq(dev, SIOCETHTOOL, &ifr);
+	if (ret) {
 		DEBUG("ioctl(SIOCETHTOOL, ETHTOOL_GLINKSETTINGS) failed: %s",
-		      strerror(errno));
-		return -1;
+		      strerror(rte_errno));
+		return ret;
 	}
 	dev_link.link_speed = ecmd->speed;
 	sc = ecmd->link_mode_masks[0] |
@@ -602,7 +631,8 @@ mlx5_link_update_unlocked_gs(struct rte_eth_dev *dev)
 		return 0;
 	}
 	/* Link status is still the same. */
-	return -1;
+	rte_errno = EAGAIN;
+	return -rte_errno;
 }
 
 /**
@@ -615,18 +645,21 @@ static void
 mlx5_link_start(struct rte_eth_dev *dev)
 {
 	struct priv *priv = dev->data->dev_private;
-	int err;
+	int ret;
 
 	dev->tx_pkt_burst = mlx5_select_tx_function(dev);
 	dev->rx_pkt_burst = mlx5_select_rx_function(dev);
-	err = mlx5_traffic_enable(dev);
-	if (err)
+	ret = mlx5_traffic_enable(dev);
+	if (ret) {
 		ERROR("%p: error occurred while configuring control flows: %s",
-		      (void *)dev, strerror(err));
-	err = mlx5_flow_start(dev, &priv->flows);
-	if (err)
+		      (void *)dev, strerror(rte_errno));
+		return;
+	}
+	ret = mlx5_flow_start(dev, &priv->flows);
+	if (ret) {
 		ERROR("%p: error occurred while configuring flows: %s",
-		      (void *)dev, strerror(err));
+		      (void *)dev, strerror(rte_errno));
+	}
 }
 
 /**
@@ -656,7 +689,7 @@ mlx5_link_stop(struct rte_eth_dev *dev)
  *   Link desired status.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_force_link_status_change(struct rte_eth_dev *dev, int status)
@@ -670,7 +703,8 @@ mlx5_force_link_status_change(struct rte_eth_dev *dev, int status)
 		try++;
 		sleep(1);
 	}
-	return -EAGAIN;
+	rte_errno = EAGAIN;
+	return -rte_errno;
 }
 
 /**
@@ -682,7 +716,7 @@ mlx5_force_link_status_change(struct rte_eth_dev *dev, int status)
  *   Wait for request completion (ignored).
  *
  * @return
- *   0 on success, -1 on error.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_link_update(struct rte_eth_dev *dev, int wait_to_complete __rte_unused)
@@ -699,10 +733,12 @@ mlx5_link_update(struct rte_eth_dev *dev, int wait_to_complete __rte_unused)
 		ret = mlx5_link_update_unlocked_gset(dev);
 	else
 		ret = mlx5_link_update_unlocked_gs(dev);
+	if (ret)
+		return ret;
 	/* If lsc interrupt is disabled, should always be ready for traffic. */
 	if (!dev->data->dev_conf.intr_conf.lsc) {
 		mlx5_link_start(dev);
-		return ret;
+		return 0;
 	}
 	/* Re-select burst callbacks only if link status has been changed. */
 	if (!ret && dev_link.link_status != dev->data->dev_link.link_status) {
@@ -711,7 +747,7 @@ mlx5_link_update(struct rte_eth_dev *dev, int wait_to_complete __rte_unused)
 		else
 			mlx5_link_stop(dev);
 	}
-	return ret;
+	return 0;
 }
 
 /**
@@ -723,36 +759,32 @@ mlx5_link_update(struct rte_eth_dev *dev, int wait_to_complete __rte_unused)
  *   New MTU.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_dev_set_mtu(struct rte_eth_dev *dev, uint16_t mtu)
 {
 	struct priv *priv = dev->data->dev_private;
-	uint16_t kern_mtu;
-	int ret = 0;
+	uint16_t kern_mtu = 0;
+	int ret;
 
 	ret = mlx5_get_mtu(dev, &kern_mtu);
 	if (ret)
-		goto out;
+		return ret;
 	/* Set kernel interface MTU first. */
 	ret = mlx5_set_mtu(dev, mtu);
 	if (ret)
-		goto out;
+		return ret;
 	ret = mlx5_get_mtu(dev, &kern_mtu);
 	if (ret)
-		goto out;
+		return ret;
 	if (kern_mtu == mtu) {
 		priv->mtu = mtu;
 		DEBUG("adapter port %u MTU set to %u", priv->port, mtu);
+		return 0;
 	}
-	return 0;
-out:
-	ret = errno;
-	WARN("cannot set port %u MTU to %u: %s", priv->port, mtu,
-	     strerror(ret));
-	assert(ret >= 0);
-	return -ret;
+	rte_errno = EAGAIN;
+	return -rte_errno;
 }
 
 /**
@@ -764,7 +796,7 @@ mlx5_dev_set_mtu(struct rte_eth_dev *dev, uint16_t mtu)
  *   Flow control output buffer.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_dev_get_flow_ctrl(struct rte_eth_dev *dev, struct rte_eth_fc_conf *fc_conf)
@@ -776,11 +808,11 @@ mlx5_dev_get_flow_ctrl(struct rte_eth_dev *dev, struct rte_eth_fc_conf *fc_conf)
 	int ret;
 
 	ifr.ifr_data = (void *)&ethpause;
-	if (mlx5_ifreq(dev, SIOCETHTOOL, &ifr)) {
-		ret = errno;
+	ret = mlx5_ifreq(dev, SIOCETHTOOL, &ifr);
+	if (ret) {
 		WARN("ioctl(SIOCETHTOOL, ETHTOOL_GPAUSEPARAM) failed: %s",
-		     strerror(ret));
-		goto out;
+		     strerror(rte_errno));
+		return ret;
 	}
 	fc_conf->autoneg = ethpause.autoneg;
 	if (ethpause.rx_pause && ethpause.tx_pause)
@@ -791,10 +823,7 @@ mlx5_dev_get_flow_ctrl(struct rte_eth_dev *dev, struct rte_eth_fc_conf *fc_conf)
 		fc_conf->mode = RTE_FC_TX_PAUSE;
 	else
 		fc_conf->mode = RTE_FC_NONE;
-	ret = 0;
-out:
-	assert(ret >= 0);
-	return -ret;
+	return 0;
 }
 
 /**
@@ -806,7 +835,7 @@ mlx5_dev_get_flow_ctrl(struct rte_eth_dev *dev, struct rte_eth_fc_conf *fc_conf)
  *   Flow control parameters.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_dev_set_flow_ctrl(struct rte_eth_dev *dev, struct rte_eth_fc_conf *fc_conf)
@@ -830,17 +859,14 @@ mlx5_dev_set_flow_ctrl(struct rte_eth_dev *dev, struct rte_eth_fc_conf *fc_conf)
 		ethpause.tx_pause = 1;
 	else
 		ethpause.tx_pause = 0;
-	if (mlx5_ifreq(dev, SIOCETHTOOL, &ifr)) {
-		ret = errno;
+	ret = mlx5_ifreq(dev, SIOCETHTOOL, &ifr);
+	if (ret) {
 		WARN("ioctl(SIOCETHTOOL, ETHTOOL_SPAUSEPARAM)"
 		     " failed: %s",
-		     strerror(ret));
-		goto out;
+		     strerror(rte_errno));
+		return ret;
 	}
-	ret = 0;
-out:
-	assert(ret >= 0);
-	return -ret;
+	return 0;
 }
 
 /**
@@ -852,7 +878,7 @@ mlx5_dev_set_flow_ctrl(struct rte_eth_dev *dev, struct rte_eth_fc_conf *fc_conf)
  *   PCI bus address output buffer.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_ibv_device_to_pci_addr(const struct ibv_device *device,
@@ -863,8 +889,10 @@ mlx5_ibv_device_to_pci_addr(const struct ibv_device *device,
 	MKSTR(path, "%s/device/uevent", device->ibdev_path);
 
 	file = fopen(path, "rb");
-	if (file == NULL)
-		return -1;
+	if (file == NULL) {
+		rte_errno = errno;
+		return -rte_errno;
+	}
 	while (fgets(line, sizeof(line), file) == line) {
 		size_t len = strlen(line);
 		int ret;
@@ -900,15 +928,19 @@ mlx5_ibv_device_to_pci_addr(const struct ibv_device *device,
  *   Pointer to Ethernet device.
  *
  * @return
- *   Zero if the callback process can be called immediately.
+ *   Zero if the callback process can be called immediately, negative errno
+ *   value otherwise and rte_errno is set.
  */
 static int
 mlx5_link_status_update(struct rte_eth_dev *dev)
 {
 	struct priv *priv = dev->data->dev_private;
 	struct rte_eth_link *link = &dev->data->dev_link;
+	int ret;
 
-	mlx5_link_update(dev, 0);
+	ret = mlx5_link_update(dev, 0);
+	if (ret)
+		return ret;
 	if (((link->link_speed == 0) && link->link_status) ||
 		((link->link_speed != 0) && !link->link_status)) {
 		/*
@@ -1062,12 +1094,13 @@ void
 mlx5_dev_interrupt_handler_install(struct rte_eth_dev *dev)
 {
 	struct priv *priv = dev->data->dev_private;
-	int rc, flags;
+	int ret;
+	int flags;
 
 	assert(priv->ctx->async_fd > 0);
 	flags = fcntl(priv->ctx->async_fd, F_GETFL);
-	rc = fcntl(priv->ctx->async_fd, F_SETFL, flags | O_NONBLOCK);
-	if (rc < 0) {
+	ret = fcntl(priv->ctx->async_fd, F_SETFL, flags | O_NONBLOCK);
+	if (ret) {
 		INFO("failed to change file descriptor async event queue");
 		dev->data->dev_conf.intr_conf.lsc = 0;
 		dev->data->dev_conf.intr_conf.rmv = 0;
@@ -1079,8 +1112,10 @@ mlx5_dev_interrupt_handler_install(struct rte_eth_dev *dev)
 		rte_intr_callback_register(&priv->intr_handle,
 					   mlx5_dev_interrupt_handler, dev);
 	}
-	rc = mlx5_socket_init(dev);
-	if (!rc && priv->primary_socket) {
+	ret = mlx5_socket_init(dev);
+	if (ret)
+		ERROR("cannot initialise socket: %s", strerror(rte_errno));
+	else if (priv->primary_socket) {
 		priv->intr_handle_socket.fd = priv->primary_socket;
 		priv->intr_handle_socket.type = RTE_INTR_HANDLE_EXT;
 		rte_intr_callback_register(&priv->intr_handle_socket,
@@ -1095,7 +1130,7 @@ mlx5_dev_interrupt_handler_install(struct rte_eth_dev *dev)
  *   Pointer to Ethernet device structure.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_set_link_down(struct rte_eth_dev *dev)
@@ -1110,7 +1145,7 @@ mlx5_set_link_down(struct rte_eth_dev *dev)
  *   Pointer to Ethernet device structure.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_set_link_up(struct rte_eth_dev *dev)
diff --git a/drivers/net/mlx5/mlx5_flow.c b/drivers/net/mlx5/mlx5_flow.c
index 6b53b3ea5..1435516dc 100644
--- a/drivers/net/mlx5/mlx5_flow.c
+++ b/drivers/net/mlx5/mlx5_flow.c
@@ -247,7 +247,8 @@ struct mlx5_flow_items {
 	 *   Internal structure to store the conversion.
 	 *
 	 * @return
-	 *   0 on success, negative value otherwise.
+	 *   0 on success, a negative errno value otherwise and rte_errno is
+	 *   set.
 	 */
 	int (*convert)(const struct rte_flow_item *item,
 		       const void *default_mask,
@@ -460,45 +461,52 @@ struct ibv_spec_header {
  *   Bit-Mask size in bytes.
  *
  * @return
- *   0 on success.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_item_validate(const struct rte_flow_item *item,
 			const uint8_t *mask, unsigned int size)
 {
-	int ret = 0;
-
-	if (!item->spec && (item->mask || item->last))
-		return -1;
+	if (!item->spec && (item->mask || item->last)) {
+		rte_errno = EINVAL;
+		return -rte_errno;
+	}
 	if (item->spec && !item->mask) {
 		unsigned int i;
 		const uint8_t *spec = item->spec;
 
 		for (i = 0; i < size; ++i)
-			if ((spec[i] | mask[i]) != mask[i])
-				return -1;
+			if ((spec[i] | mask[i]) != mask[i]) {
+				rte_errno = EINVAL;
+				return -rte_errno;
+			}
 	}
 	if (item->last && !item->mask) {
 		unsigned int i;
 		const uint8_t *spec = item->last;
 
 		for (i = 0; i < size; ++i)
-			if ((spec[i] | mask[i]) != mask[i])
-				return -1;
+			if ((spec[i] | mask[i]) != mask[i]) {
+				rte_errno = EINVAL;
+				return -rte_errno;
+			}
 	}
 	if (item->mask) {
 		unsigned int i;
 		const uint8_t *spec = item->spec;
 
 		for (i = 0; i < size; ++i)
-			if ((spec[i] | mask[i]) != mask[i])
-				return -1;
+			if ((spec[i] | mask[i]) != mask[i]) {
+				rte_errno = EINVAL;
+				return -rte_errno;
+			}
 	}
 	if (item->spec && item->last) {
 		uint8_t spec[size];
 		uint8_t last[size];
 		const uint8_t *apply = mask;
 		unsigned int i;
+		int ret;
 
 		if (item->mask)
 			apply = item->mask;
@@ -507,8 +515,12 @@ mlx5_flow_item_validate(const struct rte_flow_item *item,
 			last[i] = ((const uint8_t *)item->last)[i] & apply[i];
 		}
 		ret = memcmp(spec, last, size);
+		if (ret != 0) {
+			rte_errno = EINVAL;
+			return -rte_errno;
+		}
 	}
-	return ret;
+	return 0;
 }
 
 /**
@@ -521,7 +533,7 @@ mlx5_flow_item_validate(const struct rte_flow_item *item,
  *   User RSS configuration to save.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_convert_rss_conf(struct mlx5_flow_parse *parser,
@@ -533,10 +545,14 @@ mlx5_flow_convert_rss_conf(struct mlx5_flow_parse *parser,
 	 * device default RSS configuration.
 	 */
 	if (rss_conf) {
-		if (rss_conf->rss_hf & MLX5_RSS_HF_MASK)
-			return EINVAL;
-		if (rss_conf->rss_key_len != 40)
-			return EINVAL;
+		if (rss_conf->rss_hf & MLX5_RSS_HF_MASK) {
+			rte_errno = EINVAL;
+			return -rte_errno;
+		}
+		if (rss_conf->rss_key_len != 40) {
+			rte_errno = EINVAL;
+			return -rte_errno;
+		}
 		if (rss_conf->rss_key_len && rss_conf->rss_key) {
 			parser->rss_conf.rss_key_len = rss_conf->rss_key_len;
 			memcpy(parser->rss_key, rss_conf->rss_key,
@@ -616,14 +632,17 @@ mlx5_flow_convert_actions(struct rte_eth_dev *dev,
 			  struct mlx5_flow_parse *parser)
 {
 	struct priv *priv = dev->data->dev_private;
+	int ret;
 
 	/*
 	 * Add default RSS configuration necessary for Verbs to create QP even
 	 * if no RSS is necessary.
 	 */
-	mlx5_flow_convert_rss_conf(parser,
-				   (const struct rte_eth_rss_conf *)
-				   &priv->rss_conf);
+	ret = mlx5_flow_convert_rss_conf(parser,
+					 (const struct rte_eth_rss_conf *)
+					 &priv->rss_conf);
+	if (ret)
+		return ret;
 	for (; actions->type != RTE_FLOW_ACTION_TYPE_END; ++actions) {
 		if (actions->type == RTE_FLOW_ACTION_TYPE_VOID) {
 			continue;
@@ -772,6 +791,7 @@ mlx5_flow_convert_items_validate(const struct rte_flow_item items[],
 {
 	const struct mlx5_flow_items *cur_item = mlx5_flow_items;
 	unsigned int i;
+	int ret = 0;
 
 	/* Initialise the offsets to start after verbs attribute. */
 	for (i = 0; i != hash_rxq_init_n; ++i)
@@ -779,7 +799,6 @@ mlx5_flow_convert_items_validate(const struct rte_flow_item items[],
 	for (; items->type != RTE_FLOW_ITEM_TYPE_END; ++items) {
 		const struct mlx5_flow_items *token = NULL;
 		unsigned int n;
-		int err;
 
 		if (items->type == RTE_FLOW_ITEM_TYPE_VOID)
 			continue;
@@ -795,10 +814,10 @@ mlx5_flow_convert_items_validate(const struct rte_flow_item items[],
 		if (!token)
 			goto exit_item_not_supported;
 		cur_item = token;
-		err = mlx5_flow_item_validate(items,
+		ret = mlx5_flow_item_validate(items,
 					      (const uint8_t *)cur_item->mask,
 					      cur_item->mask_sz);
-		if (err)
+		if (ret)
 			goto exit_item_not_supported;
 		if (items->type == RTE_FLOW_ITEM_TYPE_VXLAN) {
 			if (parser->inner) {
@@ -835,9 +854,8 @@ mlx5_flow_convert_items_validate(const struct rte_flow_item items[],
 	}
 	return 0;
 exit_item_not_supported:
-	rte_flow_error_set(error, ENOTSUP, RTE_FLOW_ERROR_TYPE_ITEM,
-			   items, "item not supported");
-	return -rte_errno;
+	return rte_flow_error_set(error, -ret, RTE_FLOW_ERROR_TYPE_ITEM,
+				  items, "item not supported");
 }
 
 /**
@@ -851,7 +869,7 @@ mlx5_flow_convert_items_validate(const struct rte_flow_item items[],
  *   Perform verbose error reporting if not NULL.
  *
  * @return
- *   A verbs flow attribute on success, NULL otherwise.
+ *   A verbs flow attribute on success, NULL otherwise and rte_errno is set.
  */
 static struct ibv_flow_attr *
 mlx5_flow_convert_allocate(unsigned int priority,
@@ -1054,7 +1072,7 @@ mlx5_flow_convert(struct rte_eth_dev *dev,
 		parser->queue[HASH_RXQ_ETH].ibv_attr =
 			mlx5_flow_convert_allocate(priority, offset, error);
 		if (!parser->queue[HASH_RXQ_ETH].ibv_attr)
-			return ENOMEM;
+			goto exit_enomem;
 		parser->queue[HASH_RXQ_ETH].offset =
 			sizeof(struct ibv_flow_attr);
 	} else {
@@ -1089,7 +1107,7 @@ mlx5_flow_convert(struct rte_eth_dev *dev,
 					 cur_item->mask),
 					parser);
 		if (ret) {
-			rte_flow_error_set(error, ret,
+			rte_flow_error_set(error, rte_errno,
 					   RTE_FLOW_ERROR_TYPE_ITEM,
 					   items, "item not supported");
 			goto exit_free;
@@ -1131,13 +1149,13 @@ mlx5_flow_convert(struct rte_eth_dev *dev,
 			parser->queue[i].ibv_attr = NULL;
 		}
 	}
-	rte_flow_error_set(error, ENOTSUP, RTE_FLOW_ERROR_TYPE_UNSPECIFIED,
+	rte_flow_error_set(error, ENOMEM, RTE_FLOW_ERROR_TYPE_UNSPECIFIED,
 			   NULL, "cannot allocate verbs spec attributes.");
-	return ret;
+	return -rte_errno;
 exit_count_error:
 	rte_flow_error_set(error, EINVAL, RTE_FLOW_ERROR_TYPE_UNSPECIFIED,
 			   NULL, "cannot create counter.");
-	return rte_errno;
+	return -rte_errno;
 }
 
 /**
@@ -1183,6 +1201,9 @@ mlx5_flow_create_copy(struct mlx5_flow_parse *parser, void *src,
  *   Default bit-masks to use when item->mask is not provided.
  * @param data[in, out]
  *   User structure.
+ *
+ * @return
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_create_eth(const struct rte_flow_item *item,
@@ -1232,6 +1253,9 @@ mlx5_flow_create_eth(const struct rte_flow_item *item,
  *   Default bit-masks to use when item->mask is not provided.
  * @param data[in, out]
  *   User structure.
+ *
+ * @return
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_create_vlan(const struct rte_flow_item *item,
@@ -1272,6 +1296,9 @@ mlx5_flow_create_vlan(const struct rte_flow_item *item,
  *   Default bit-masks to use when item->mask is not provided.
  * @param data[in, out]
  *   User structure.
+ *
+ * @return
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_create_ipv4(const struct rte_flow_item *item,
@@ -1324,6 +1351,9 @@ mlx5_flow_create_ipv4(const struct rte_flow_item *item,
  *   Default bit-masks to use when item->mask is not provided.
  * @param data[in, out]
  *   User structure.
+ *
+ * @return
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_create_ipv6(const struct rte_flow_item *item,
@@ -1396,6 +1426,9 @@ mlx5_flow_create_ipv6(const struct rte_flow_item *item,
  *   Default bit-masks to use when item->mask is not provided.
  * @param data[in, out]
  *   User structure.
+ *
+ * @return
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_create_udp(const struct rte_flow_item *item,
@@ -1442,6 +1475,9 @@ mlx5_flow_create_udp(const struct rte_flow_item *item,
  *   Default bit-masks to use when item->mask is not provided.
  * @param data[in, out]
  *   User structure.
+ *
+ * @return
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_create_tcp(const struct rte_flow_item *item,
@@ -1488,6 +1524,9 @@ mlx5_flow_create_tcp(const struct rte_flow_item *item,
  *   Default bit-masks to use when item->mask is not provided.
  * @param data[in, out]
  *   User structure.
+ *
+ * @return
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_create_vxlan(const struct rte_flow_item *item,
@@ -1527,8 +1566,10 @@ mlx5_flow_create_vxlan(const struct rte_flow_item *item,
 	 * before will also match this rule.
 	 * To avoid such situation, VNI 0 is currently refused.
 	 */
-	if (!vxlan.val.tunnel_id)
-		return EINVAL;
+	if (!vxlan.val.tunnel_id) {
+		rte_errno = EINVAL;
+		return -rte_errno;
+	}
 	mlx5_flow_create_copy(parser, &vxlan, size);
 	return 0;
 }
@@ -1540,6 +1581,9 @@ mlx5_flow_create_vxlan(const struct rte_flow_item *item,
  *   Internal parser structure.
  * @param mark_id
  *   Mark identifier.
+ *
+ * @return
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_create_flag_mark(struct mlx5_flow_parse *parser, uint32_t mark_id)
@@ -1565,7 +1609,7 @@ mlx5_flow_create_flag_mark(struct mlx5_flow_parse *parser, uint32_t mark_id)
  *   Pointer to MLX5 flow parser structure.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_create_count(struct rte_eth_dev *dev __rte_unused,
@@ -1583,8 +1627,10 @@ mlx5_flow_create_count(struct rte_eth_dev *dev __rte_unused,
 
 	init_attr.counter_set_id = 0;
 	parser->cs = mlx5_glue->create_counter_set(priv->ctx, &init_attr);
-	if (!parser->cs)
-		return EINVAL;
+	if (!parser->cs) {
+		rte_errno = EINVAL;
+		return -rte_errno;
+	}
 	counter.counter_set_handle = parser->cs->handle;
 	mlx5_flow_create_copy(parser, &counter, size);
 #endif
@@ -1604,7 +1650,7 @@ mlx5_flow_create_count(struct rte_eth_dev *dev __rte_unused,
  *   Perform verbose error reporting if not NULL.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_create_action_queue_drop(struct rte_eth_dev *dev,
@@ -1615,7 +1661,6 @@ mlx5_flow_create_action_queue_drop(struct rte_eth_dev *dev,
 	struct priv *priv = dev->data->dev_private;
 	struct ibv_flow_spec_action_drop *drop;
 	unsigned int size = sizeof(struct ibv_flow_spec_action_drop);
-	int err = 0;
 
 	assert(priv->pd);
 	assert(priv->ctx);
@@ -1641,7 +1686,6 @@ mlx5_flow_create_action_queue_drop(struct rte_eth_dev *dev,
 	if (!flow->frxq[HASH_RXQ_ETH].ibv_flow) {
 		rte_flow_error_set(error, ENOMEM, RTE_FLOW_ERROR_TYPE_HANDLE,
 				   NULL, "flow rule creation failure");
-		err = ENOMEM;
 		goto error;
 	}
 	return 0;
@@ -1661,7 +1705,7 @@ mlx5_flow_create_action_queue_drop(struct rte_eth_dev *dev,
 		flow->cs = NULL;
 		parser->cs = NULL;
 	}
-	return err;
+	return -rte_errno;
 }
 
 /**
@@ -1677,7 +1721,7 @@ mlx5_flow_create_action_queue_drop(struct rte_eth_dev *dev,
  *   Perform verbose error reporting if not NULL.
  *
  * @return
- *   0 on success, a errno value otherwise and rte_errno is set.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_create_action_queue_rss(struct rte_eth_dev *dev,
@@ -1715,10 +1759,10 @@ mlx5_flow_create_action_queue_rss(struct rte_eth_dev *dev,
 				      parser->queues,
 				      parser->queues_n);
 		if (!flow->frxq[i].hrxq) {
-			rte_flow_error_set(error, ENOMEM,
-					   RTE_FLOW_ERROR_TYPE_HANDLE,
-					   NULL, "cannot create hash rxq");
-			return ENOMEM;
+			return rte_flow_error_set(error, ENOMEM,
+						  RTE_FLOW_ERROR_TYPE_HANDLE,
+						  NULL,
+						  "cannot create hash rxq");
 		}
 	}
 	return 0;
@@ -1737,7 +1781,7 @@ mlx5_flow_create_action_queue_rss(struct rte_eth_dev *dev,
  *   Perform verbose error reporting if not NULL.
  *
  * @return
- *   0 on success, a errno value otherwise and rte_errno is set.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_create_action_queue(struct rte_eth_dev *dev,
@@ -1746,14 +1790,14 @@ mlx5_flow_create_action_queue(struct rte_eth_dev *dev,
 			      struct rte_flow_error *error)
 {
 	struct priv *priv = dev->data->dev_private;
-	int err = 0;
+	int ret;
 	unsigned int i;
 
 	assert(priv->pd);
 	assert(priv->ctx);
 	assert(!parser->drop);
-	err = mlx5_flow_create_action_queue_rss(dev, parser, flow, error);
-	if (err)
+	ret = mlx5_flow_create_action_queue_rss(dev, parser, flow, error);
+	if (ret)
 		goto error;
 	if (parser->count)
 		flow->cs = parser->cs;
@@ -1769,7 +1813,6 @@ mlx5_flow_create_action_queue(struct rte_eth_dev *dev,
 			rte_flow_error_set(error, ENOMEM,
 					   RTE_FLOW_ERROR_TYPE_HANDLE,
 					   NULL, "flow rule creation failure");
-			err = ENOMEM;
 			goto error;
 		}
 		DEBUG("%p type %d QP %p ibv_flow %p",
@@ -1785,6 +1828,7 @@ mlx5_flow_create_action_queue(struct rte_eth_dev *dev,
 	}
 	return 0;
 error:
+	ret = rte_errno; /* Save rte_errno before cleanup. */
 	assert(flow);
 	for (i = 0; i != hash_rxq_init_n; ++i) {
 		if (flow->frxq[i].ibv_flow) {
@@ -1802,7 +1846,8 @@ mlx5_flow_create_action_queue(struct rte_eth_dev *dev,
 		flow->cs = NULL;
 		parser->cs = NULL;
 	}
-	return err;
+	rte_errno = ret; /* Restore rte_errno. */
+	return -rte_errno;
 }
 
 /**
@@ -1822,7 +1867,7 @@ mlx5_flow_create_action_queue(struct rte_eth_dev *dev,
  *   Perform verbose error reporting if not NULL.
  *
  * @return
- *   A flow on success, NULL otherwise.
+ *   A flow on success, NULL otherwise and rte_errno is set.
  */
 static struct rte_flow *
 mlx5_flow_list_create(struct rte_eth_dev *dev,
@@ -1835,10 +1880,10 @@ mlx5_flow_list_create(struct rte_eth_dev *dev,
 	struct mlx5_flow_parse parser = { .create = 1, };
 	struct rte_flow *flow = NULL;
 	unsigned int i;
-	int err;
+	int ret;
 
-	err = mlx5_flow_convert(dev, attr, items, actions, error, &parser);
-	if (err)
+	ret = mlx5_flow_convert(dev, attr, items, actions, error, &parser);
+	if (ret)
 		goto exit;
 	flow = rte_calloc(__func__, 1,
 			  sizeof(*flow) + parser.queues_n * sizeof(uint16_t),
@@ -1861,11 +1906,11 @@ mlx5_flow_list_create(struct rte_eth_dev *dev,
 	memcpy(flow->rss_key, parser.rss_key, parser.rss_conf.rss_key_len);
 	/* finalise the flow. */
 	if (parser.drop)
-		err = mlx5_flow_create_action_queue_drop(dev, &parser, flow,
+		ret = mlx5_flow_create_action_queue_drop(dev, &parser, flow,
 							 error);
 	else
-		err = mlx5_flow_create_action_queue(dev, &parser, flow, error);
-	if (err)
+		ret = mlx5_flow_create_action_queue(dev, &parser, flow, error);
+	if (ret)
 		goto exit;
 	TAILQ_INSERT_TAIL(list, flow, next);
 	DEBUG("Flow created %p", (void *)flow);
@@ -1893,11 +1938,9 @@ mlx5_flow_validate(struct rte_eth_dev *dev,
 		   const struct rte_flow_action actions[],
 		   struct rte_flow_error *error)
 {
-	int ret;
 	struct mlx5_flow_parse parser = { .create = 0, };
 
-	ret = mlx5_flow_convert(dev, attr, items, actions, error, &parser);
-	return ret;
+	return mlx5_flow_convert(dev, attr, items, actions, error, &parser);
 }
 
 /**
@@ -2021,7 +2064,7 @@ mlx5_flow_list_flush(struct rte_eth_dev *dev, struct mlx5_flows *list)
  *   Pointer to Ethernet device.
  *
  * @return
- *   0 on success.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_flow_create_drop_queue(struct rte_eth_dev *dev)
@@ -2034,11 +2077,13 @@ mlx5_flow_create_drop_queue(struct rte_eth_dev *dev)
 	fdq = rte_calloc(__func__, 1, sizeof(*fdq), 0);
 	if (!fdq) {
 		WARN("cannot allocate memory for drop queue");
-		goto error;
+		rte_errno = ENOMEM;
+		return -rte_errno;
 	}
 	fdq->cq = mlx5_glue->create_cq(priv->ctx, 1, NULL, NULL, 0);
 	if (!fdq->cq) {
 		WARN("cannot allocate CQ for drop queue");
+		rte_errno = errno;
 		goto error;
 	}
 	fdq->wq = mlx5_glue->create_wq
@@ -2052,6 +2097,7 @@ mlx5_flow_create_drop_queue(struct rte_eth_dev *dev)
 		 });
 	if (!fdq->wq) {
 		WARN("cannot allocate WQ for drop queue");
+		rte_errno = errno;
 		goto error;
 	}
 	fdq->ind_table = mlx5_glue->create_rwq_ind_table
@@ -2063,6 +2109,7 @@ mlx5_flow_create_drop_queue(struct rte_eth_dev *dev)
 		 });
 	if (!fdq->ind_table) {
 		WARN("cannot allocate indirection table for drop queue");
+		rte_errno = errno;
 		goto error;
 	}
 	fdq->qp = mlx5_glue->create_qp_ex
@@ -2085,6 +2132,7 @@ mlx5_flow_create_drop_queue(struct rte_eth_dev *dev)
 		 });
 	if (!fdq->qp) {
 		WARN("cannot allocate QP for drop queue");
+		rte_errno = errno;
 		goto error;
 	}
 	priv->flow_drop_queue = fdq;
@@ -2101,7 +2149,7 @@ mlx5_flow_create_drop_queue(struct rte_eth_dev *dev)
 	if (fdq)
 		rte_free(fdq);
 	priv->flow_drop_queue = NULL;
-	return -1;
+	return -rte_errno;
 }
 
 /**
@@ -2200,7 +2248,7 @@ mlx5_flow_stop(struct rte_eth_dev *dev, struct mlx5_flows *list)
  *   Pointer to a TAILQ flow list.
  *
  * @return
- *   0 on success, a errno value otherwise and rte_errno is set.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_flow_start(struct rte_eth_dev *dev, struct mlx5_flows *list)
@@ -2220,7 +2268,7 @@ mlx5_flow_start(struct rte_eth_dev *dev, struct mlx5_flows *list)
 				DEBUG("Flow %p cannot be applied",
 				      (void *)flow);
 				rte_errno = EINVAL;
-				return rte_errno;
+				return -rte_errno;
 			}
 			DEBUG("Flow %p applied", (void *)flow);
 			/* Next flow. */
@@ -2247,7 +2295,7 @@ mlx5_flow_start(struct rte_eth_dev *dev, struct mlx5_flows *list)
 				DEBUG("Flow %p cannot be applied",
 				      (void *)flow);
 				rte_errno = EINVAL;
-				return rte_errno;
+				return -rte_errno;
 			}
 flow_create:
 			flow->frxq[i].ibv_flow =
@@ -2257,7 +2305,7 @@ mlx5_flow_start(struct rte_eth_dev *dev, struct mlx5_flows *list)
 				DEBUG("Flow %p cannot be applied",
 				      (void *)flow);
 				rte_errno = EINVAL;
-				return rte_errno;
+				return -rte_errno;
 			}
 			DEBUG("Flow %p applied", (void *)flow);
 		}
@@ -2307,7 +2355,7 @@ mlx5_flow_verify(struct rte_eth_dev *dev)
  *   A VLAN flow mask to apply.
  *
  * @return
- *   0 on success.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_ctrl_flow_vlan(struct rte_eth_dev *dev,
@@ -2359,8 +2407,10 @@ mlx5_ctrl_flow_vlan(struct rte_eth_dev *dev,
 		} local;
 	} action_rss;
 
-	if (!priv->reta_idx_n)
-		return EINVAL;
+	if (!priv->reta_idx_n) {
+		rte_errno = EINVAL;
+		return -rte_errno;
+	}
 	for (i = 0; i != priv->reta_idx_n; ++i)
 		action_rss.local.queue[i] = (*priv->reta_idx)[i];
 	action_rss.local.rss_conf = &priv->rss_conf;
@@ -2369,7 +2419,7 @@ mlx5_ctrl_flow_vlan(struct rte_eth_dev *dev,
 	flow = mlx5_flow_list_create(dev, &priv->ctrl_flows, &attr, items,
 				     actions, &error);
 	if (!flow)
-		return rte_errno;
+		return -rte_errno;
 	return 0;
 }
 
@@ -2384,7 +2434,7 @@ mlx5_ctrl_flow_vlan(struct rte_eth_dev *dev,
  *   An Ethernet flow mask to apply.
  *
  * @return
- *   0 on success.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_ctrl_flow(struct rte_eth_dev *dev,
@@ -2437,7 +2487,7 @@ mlx5_flow_flush(struct rte_eth_dev *dev,
  *   returned data from the counter.
  *
  * @return
- *   0 on success, a errno value otherwise and rte_errno is set.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_flow_query_count(struct ibv_counter_set *cs,
@@ -2454,15 +2504,13 @@ mlx5_flow_query_count(struct ibv_counter_set *cs,
 		.out = counters,
 		.outlen = 2 * sizeof(uint64_t),
 	};
-	int res = mlx5_glue->query_counter_set(&query_cs_attr, &query_out);
+	int err = mlx5_glue->query_counter_set(&query_cs_attr, &query_out);
 
-	if (res) {
-		rte_flow_error_set(error, -res,
-				   RTE_FLOW_ERROR_TYPE_UNSPECIFIED,
-				   NULL,
-				   "cannot read counter");
-		return -res;
-	}
+	if (err)
+		return rte_flow_error_set(error, err,
+					  RTE_FLOW_ERROR_TYPE_UNSPECIFIED,
+					  NULL,
+					  "cannot read counter");
 	query_count->hits_set = 1;
 	query_count->bytes_set = 1;
 	query_count->hits = counters[0] - counter_stats->hits;
@@ -2487,20 +2535,22 @@ mlx5_flow_query(struct rte_eth_dev *dev __rte_unused,
 		void *data,
 		struct rte_flow_error *error)
 {
-	int res = EINVAL;
-
 	if (flow->cs) {
-		res = mlx5_flow_query_count(flow->cs,
-					&flow->counter_stats,
-					(struct rte_flow_query_count *)data,
-					error);
+		int ret;
+
+		ret = mlx5_flow_query_count(flow->cs,
+					    &flow->counter_stats,
+					    (struct rte_flow_query_count *)data,
+					    error);
+		if (ret)
+			return ret;
 	} else {
-		rte_flow_error_set(error, res,
-				   RTE_FLOW_ERROR_TYPE_UNSPECIFIED,
-				   NULL,
-				   "no counter found for flow");
+		return rte_flow_error_set(error, EINVAL,
+					  RTE_FLOW_ERROR_TYPE_UNSPECIFIED,
+					  NULL,
+					  "no counter found for flow");
 	}
-	return -res;
+	return 0;
 }
 #endif
 
@@ -2543,7 +2593,7 @@ mlx5_flow_isolate(struct rte_eth_dev *dev,
  *   Generic flow parameters structure.
  *
  * @return
- *  0 on success, errno value on error.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_fdir_filter_convert(struct rte_eth_dev *dev,
@@ -2556,7 +2606,8 @@ mlx5_fdir_filter_convert(struct rte_eth_dev *dev,
 	/* Validate queue number. */
 	if (fdir_filter->action.rx_queue >= priv->rxqs_n) {
 		ERROR("invalid queue number %d", fdir_filter->action.rx_queue);
-		return EINVAL;
+		rte_errno = EINVAL;
+		return -rte_errno;
 	}
 	attributes->attr.ingress = 1;
 	attributes->items[0] = (struct rte_flow_item) {
@@ -2578,7 +2629,8 @@ mlx5_fdir_filter_convert(struct rte_eth_dev *dev,
 		break;
 	default:
 		ERROR("invalid behavior %d", fdir_filter->action.behavior);
-		return ENOTSUP;
+		rte_errno = ENOTSUP;
+		return -rte_errno;
 	}
 	attributes->queue.index = fdir_filter->action.rx_queue;
 	switch (fdir_filter->input.flow_type) {
@@ -2712,9 +2764,9 @@ mlx5_fdir_filter_convert(struct rte_eth_dev *dev,
 		};
 		break;
 	default:
-		ERROR("invalid flow type%d",
-		      fdir_filter->input.flow_type);
-		return ENOTSUP;
+		ERROR("invalid flow type%d", fdir_filter->input.flow_type);
+		rte_errno = ENOTSUP;
+		return -rte_errno;
 	}
 	return 0;
 }
@@ -2728,7 +2780,7 @@ mlx5_fdir_filter_convert(struct rte_eth_dev *dev,
  *   Flow director filter to add.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_fdir_filter_add(struct rte_eth_dev *dev,
@@ -2752,11 +2804,11 @@ mlx5_fdir_filter_add(struct rte_eth_dev *dev,
 
 	ret = mlx5_fdir_filter_convert(dev, fdir_filter, &attributes);
 	if (ret)
-		return -ret;
+		return ret;
 	ret = mlx5_flow_convert(dev, &attributes.attr, attributes.items,
 				attributes.actions, &error, &parser);
 	if (ret)
-		return -ret;
+		return ret;
 	flow = mlx5_flow_list_create(dev, &priv->flows, &attributes.attr,
 				     attributes.items, attributes.actions,
 				     &error);
@@ -2764,7 +2816,7 @@ mlx5_fdir_filter_add(struct rte_eth_dev *dev,
 		DEBUG("FDIR created %p", (void *)flow);
 		return 0;
 	}
-	return ENOTSUP;
+	return -rte_errno;
 }
 
 /**
@@ -2776,7 +2828,7 @@ mlx5_fdir_filter_add(struct rte_eth_dev *dev,
  *   Filter to be deleted.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_fdir_filter_delete(struct rte_eth_dev *dev,
@@ -2797,7 +2849,7 @@ mlx5_fdir_filter_delete(struct rte_eth_dev *dev,
 
 	ret = mlx5_fdir_filter_convert(dev, fdir_filter, &attributes);
 	if (ret)
-		return -ret;
+		return ret;
 	ret = mlx5_flow_convert(dev, &attributes.attr, attributes.items,
 				attributes.actions, &error, &parser);
 	if (ret)
@@ -2855,6 +2907,7 @@ mlx5_fdir_filter_delete(struct rte_eth_dev *dev,
 		/* The flow does not match. */
 		continue;
 	}
+	ret = rte_errno; /* Save rte_errno before cleanup. */
 	if (flow)
 		mlx5_flow_list_destroy(dev, &priv->flows, flow);
 exit:
@@ -2862,7 +2915,8 @@ mlx5_fdir_filter_delete(struct rte_eth_dev *dev,
 		if (parser.queue[i].ibv_attr)
 			rte_free(parser.queue[i].ibv_attr);
 	}
-	return -ret;
+	rte_errno = ret; /* Restore rte_errno. */
+	return -rte_errno;
 }
 
 /**
@@ -2874,7 +2928,7 @@ mlx5_fdir_filter_delete(struct rte_eth_dev *dev,
  *   Filter to be updated.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_fdir_filter_update(struct rte_eth_dev *dev,
@@ -2885,8 +2939,7 @@ mlx5_fdir_filter_update(struct rte_eth_dev *dev,
 	ret = mlx5_fdir_filter_delete(dev, fdir_filter);
 	if (ret)
 		return ret;
-	ret = mlx5_fdir_filter_add(dev, fdir_filter);
-	return ret;
+	return mlx5_fdir_filter_add(dev, fdir_filter);
 }
 
 /**
@@ -2940,7 +2993,7 @@ mlx5_fdir_info_get(struct rte_eth_dev *dev, struct rte_eth_fdir_info *fdir_info)
  *   Pointer to operation-specific structure.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_fdir_ctrl_func(struct rte_eth_dev *dev, enum rte_filter_op filter_op,
@@ -2949,7 +3002,6 @@ mlx5_fdir_ctrl_func(struct rte_eth_dev *dev, enum rte_filter_op filter_op,
 	struct priv *priv = dev->data->dev_private;
 	enum rte_fdir_mode fdir_mode =
 		priv->dev->data->dev_conf.fdir_conf.mode;
-	int ret = 0;
 
 	if (filter_op == RTE_ETH_FILTER_NOP)
 		return 0;
@@ -2957,18 +3009,16 @@ mlx5_fdir_ctrl_func(struct rte_eth_dev *dev, enum rte_filter_op filter_op,
 	    fdir_mode != RTE_FDIR_MODE_PERFECT_MAC_VLAN) {
 		ERROR("%p: flow director mode %d not supported",
 		      (void *)dev, fdir_mode);
-		return EINVAL;
+		rte_errno = EINVAL;
+		return -rte_errno;
 	}
 	switch (filter_op) {
 	case RTE_ETH_FILTER_ADD:
-		ret = mlx5_fdir_filter_add(dev, arg);
-		break;
+		return mlx5_fdir_filter_add(dev, arg);
 	case RTE_ETH_FILTER_UPDATE:
-		ret = mlx5_fdir_filter_update(dev, arg);
-		break;
+		return mlx5_fdir_filter_update(dev, arg);
 	case RTE_ETH_FILTER_DELETE:
-		ret = mlx5_fdir_filter_delete(dev, arg);
-		break;
+		return mlx5_fdir_filter_delete(dev, arg);
 	case RTE_ETH_FILTER_FLUSH:
 		mlx5_fdir_filter_flush(dev);
 		break;
@@ -2976,12 +3026,11 @@ mlx5_fdir_ctrl_func(struct rte_eth_dev *dev, enum rte_filter_op filter_op,
 		mlx5_fdir_info_get(dev, arg);
 		break;
 	default:
-		DEBUG("%p: unknown operation %u", (void *)dev,
-		      filter_op);
-		ret = EINVAL;
-		break;
+		DEBUG("%p: unknown operation %u", (void *)dev, filter_op);
+		rte_errno = EINVAL;
+		return -rte_errno;
 	}
-	return ret;
+	return 0;
 }
 
 /**
@@ -2997,7 +3046,7 @@ mlx5_fdir_ctrl_func(struct rte_eth_dev *dev, enum rte_filter_op filter_op,
  *   Pointer to operation-specific structure.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_dev_filter_ctrl(struct rte_eth_dev *dev,
@@ -3005,21 +3054,21 @@ mlx5_dev_filter_ctrl(struct rte_eth_dev *dev,
 		     enum rte_filter_op filter_op,
 		     void *arg)
 {
-	int ret = EINVAL;
-
 	switch (filter_type) {
 	case RTE_ETH_FILTER_GENERIC:
-		if (filter_op != RTE_ETH_FILTER_GET)
-			return -EINVAL;
+		if (filter_op != RTE_ETH_FILTER_GET) {
+			rte_errno = EINVAL;
+			return -rte_errno;
+		}
 		*(const void **)arg = &mlx5_flow_ops;
 		return 0;
 	case RTE_ETH_FILTER_FDIR:
-		ret = mlx5_fdir_ctrl_func(dev, filter_op, arg);
-		break;
+		return mlx5_fdir_ctrl_func(dev, filter_op, arg);
 	default:
 		ERROR("%p: filter type (%d) not supported",
 		      (void *)dev, filter_type);
-		break;
+		rte_errno = ENOTSUP;
+		return -rte_errno;
 	}
-	return -ret;
+	return 0;
 }
diff --git a/drivers/net/mlx5/mlx5_mac.c b/drivers/net/mlx5/mlx5_mac.c
index 91c977bc5..ba54c055e 100644
--- a/drivers/net/mlx5/mlx5_mac.c
+++ b/drivers/net/mlx5/mlx5_mac.c
@@ -41,15 +41,17 @@
  *   MAC address output buffer.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_get_mac(struct rte_eth_dev *dev, uint8_t (*mac)[ETHER_ADDR_LEN])
 {
 	struct ifreq request;
+	int ret;
 
-	if (mlx5_ifreq(dev, SIOCGIFHWADDR, &request))
-		return -1;
+	ret = mlx5_ifreq(dev, SIOCGIFHWADDR, &request);
+	if (ret)
+		return ret;
 	memcpy(mac, request.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
 	return 0;
 }
@@ -67,8 +69,13 @@ mlx5_mac_addr_remove(struct rte_eth_dev *dev, uint32_t index)
 {
 	assert(index < MLX5_MAX_MAC_ADDRESSES);
 	memset(&dev->data->mac_addrs[index], 0, sizeof(struct ether_addr));
-	if (!dev->data->promiscuous)
-		mlx5_traffic_restart(dev);
+	if (!dev->data->promiscuous) {
+		int ret = mlx5_traffic_restart(dev);
+
+		if (ret)
+			ERROR("%p cannot remove mac address: %s", (void *)dev,
+			      strerror(rte_errno));
+	}
 }
 
 /**
@@ -84,14 +91,13 @@ mlx5_mac_addr_remove(struct rte_eth_dev *dev, uint32_t index)
  *   VMDq pool index to associate address with (ignored).
  *
  * @return
- *   0 on success.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_mac_addr_add(struct rte_eth_dev *dev, struct ether_addr *mac,
 		  uint32_t index, uint32_t vmdq __rte_unused)
 {
 	unsigned int i;
-	int ret = 0;
 
 	assert(index < MLX5_MAX_MAC_ADDRESSES);
 	/* First, make sure this address isn't already configured. */
@@ -102,12 +108,13 @@ mlx5_mac_addr_add(struct rte_eth_dev *dev, struct ether_addr *mac,
 		if (memcmp(&dev->data->mac_addrs[i], mac, sizeof(*mac)))
 			continue;
 		/* Address already configured elsewhere, return with error. */
-		return EADDRINUSE;
+		rte_errno = EADDRINUSE;
+		return -rte_errno;
 	}
 	dev->data->mac_addrs[index] = *mac;
 	if (!dev->data->promiscuous)
-		mlx5_traffic_restart(dev);
-	return ret;
+		return mlx5_traffic_restart(dev);
+	return 0;
 }
 
 /**
@@ -121,6 +128,10 @@ mlx5_mac_addr_add(struct rte_eth_dev *dev, struct ether_addr *mac,
 void
 mlx5_mac_addr_set(struct rte_eth_dev *dev, struct ether_addr *mac_addr)
 {
+	int ret;
+
 	DEBUG("%p: setting primary MAC address", (void *)dev);
-	mlx5_mac_addr_add(dev, mac_addr, 0, 0);
+	ret = mlx5_mac_addr_add(dev, mac_addr, 0, 0);
+	if (ret)
+		ERROR("cannot set mac address: %s", strerror(rte_errno));
 }
diff --git a/drivers/net/mlx5/mlx5_mr.c b/drivers/net/mlx5/mlx5_mr.c
index 5c4e68736..884ac33eb 100644
--- a/drivers/net/mlx5/mlx5_mr.c
+++ b/drivers/net/mlx5/mlx5_mr.c
@@ -91,7 +91,7 @@ mlx5_check_mempool(struct rte_mempool *mp, uintptr_t *start,
  *   Index of the next available entry.
  *
  * @return
- *   mr on success, NULL on failure.
+ *   mr on success, NULL on failure and rte_errno is set.
  */
 struct mlx5_mr *
 mlx5_txq_mp2mr_reg(struct mlx5_txq_data *txq, struct rte_mempool *mp,
@@ -115,6 +115,7 @@ mlx5_txq_mp2mr_reg(struct mlx5_txq_data *txq, struct rte_mempool *mp,
 			      " rte_eth_dev_start()",
 			     (void *)mp, mp->name);
 			rte_spinlock_unlock(&txq_ctrl->priv->mr_lock);
+			rte_errno = ENOTSUP;
 			return NULL;
 		}
 		mr = mlx5_mr_new(dev, mp);
@@ -203,7 +204,9 @@ mlx5_mp2mr_iter(struct rte_mempool *mp, void *arg)
 		mlx5_mr_release(mr);
 		return;
 	}
-	mlx5_mr_new(priv->dev, mp);
+	mr = mlx5_mr_new(priv->dev, mp);
+	if (!mr)
+		ERROR("cannot create memory region: %s", strerror(rte_errno));
 }
 
 /**
@@ -216,7 +219,7 @@ mlx5_mp2mr_iter(struct rte_mempool *mp, void *arg)
  *   Pointer to the memory pool to register.
  *
  * @return
- *   The memory region on success.
+ *   The memory region on success, NULL on failure and rte_errno is set.
  */
 struct mlx5_mr *
 mlx5_mr_new(struct rte_eth_dev *dev, struct rte_mempool *mp)
@@ -231,11 +234,13 @@ mlx5_mr_new(struct rte_eth_dev *dev, struct rte_mempool *mp)
 	mr = rte_zmalloc_socket(__func__, sizeof(*mr), 0, mp->socket_id);
 	if (!mr) {
 		DEBUG("unable to configure MR, ibv_reg_mr() failed.");
+		rte_errno = ENOMEM;
 		return NULL;
 	}
 	if (mlx5_check_mempool(mp, &start, &end) != 0) {
 		ERROR("mempool %p: not virtually contiguous",
 		      (void *)mp);
+		rte_errno = ENOMEM;
 		return NULL;
 	}
 	DEBUG("mempool %p area start=%p end=%p size=%zu",
@@ -260,6 +265,10 @@ mlx5_mr_new(struct rte_eth_dev *dev, struct rte_mempool *mp)
 	      (size_t)(end - start));
 	mr->mr = mlx5_glue->reg_mr(priv->pd, (void *)start, end - start,
 				   IBV_ACCESS_LOCAL_WRITE);
+	if (!mr->mr) {
+		rte_errno = ENOMEM;
+		return NULL;
+	}
 	mr->mp = mp;
 	mr->lkey = rte_cpu_to_be_32(mr->mr->lkey);
 	rte_atomic32_inc(&mr->refcnt);
diff --git a/drivers/net/mlx5/mlx5_rss.c b/drivers/net/mlx5/mlx5_rss.c
index a654a5a7d..5ac650163 100644
--- a/drivers/net/mlx5/mlx5_rss.c
+++ b/drivers/net/mlx5/mlx5_rss.c
@@ -35,33 +35,31 @@
  *   RSS configuration data.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_rss_hash_update(struct rte_eth_dev *dev,
 		     struct rte_eth_rss_conf *rss_conf)
 {
 	struct priv *priv = dev->data->dev_private;
-	int ret = 0;
 
 	if (rss_conf->rss_hf & MLX5_RSS_HF_MASK) {
-		ret = -EINVAL;
-		goto out;
+		rte_errno = EINVAL;
+		return -rte_errno;
 	}
 	if (rss_conf->rss_key && rss_conf->rss_key_len) {
 		priv->rss_conf.rss_key = rte_realloc(priv->rss_conf.rss_key,
 						     rss_conf->rss_key_len, 0);
 		if (!priv->rss_conf.rss_key) {
-			ret = -ENOMEM;
-			goto out;
+			rte_errno = ENOMEM;
+			return -rte_errno;
 		}
 		memcpy(priv->rss_conf.rss_key, rss_conf->rss_key,
 		       rss_conf->rss_key_len);
 		priv->rss_conf.rss_key_len = rss_conf->rss_key_len;
 	}
 	priv->rss_conf.rss_hf = rss_conf->rss_hf;
-out:
-	return ret;
+	return 0;
 }
 
 /**
@@ -73,7 +71,7 @@ mlx5_rss_hash_update(struct rte_eth_dev *dev,
  *   RSS configuration data.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_rss_hash_conf_get(struct rte_eth_dev *dev,
@@ -81,8 +79,10 @@ mlx5_rss_hash_conf_get(struct rte_eth_dev *dev,
 {
 	struct priv *priv = dev->data->dev_private;
 
-	if (!rss_conf)
-		return -EINVAL;
+	if (!rss_conf) {
+		rte_errno = EINVAL;
+		return -rte_errno;
+	}
 	if (rss_conf->rss_key &&
 	    (rss_conf->rss_key_len >= priv->rss_conf.rss_key_len)) {
 		memcpy(rss_conf->rss_key, priv->rss_conf.rss_key,
@@ -102,7 +102,7 @@ mlx5_rss_hash_conf_get(struct rte_eth_dev *dev,
  *   The size of the array to allocate.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_rss_reta_index_resize(struct rte_eth_dev *dev, unsigned int reta_size)
@@ -116,8 +116,10 @@ mlx5_rss_reta_index_resize(struct rte_eth_dev *dev, unsigned int reta_size)
 
 	mem = rte_realloc(priv->reta_idx,
 			  reta_size * sizeof((*priv->reta_idx)[0]), 0);
-	if (!mem)
-		return ENOMEM;
+	if (!mem) {
+		rte_errno = ENOMEM;
+		return -rte_errno;
+	}
 	priv->reta_idx = mem;
 	priv->reta_idx_n = reta_size;
 	if (old_size < reta_size)
@@ -138,7 +140,7 @@ mlx5_rss_reta_index_resize(struct rte_eth_dev *dev, unsigned int reta_size)
  *   Size of the RETA table.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_dev_rss_reta_query(struct rte_eth_dev *dev,
@@ -149,8 +151,10 @@ mlx5_dev_rss_reta_query(struct rte_eth_dev *dev,
 	unsigned int idx;
 	unsigned int i;
 
-	if (!reta_size || reta_size > priv->reta_idx_n)
-		return -EINVAL;
+	if (!reta_size || reta_size > priv->reta_idx_n) {
+		rte_errno = EINVAL;
+		return -rte_errno;
+	}
 	/* Fill each entry of the table even if its bit is not set. */
 	for (idx = 0, i = 0; (i != reta_size); ++i) {
 		idx = i / RTE_RETA_GROUP_SIZE;
@@ -171,7 +175,7 @@ mlx5_dev_rss_reta_query(struct rte_eth_dev *dev,
  *   Size of the RETA table.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_dev_rss_reta_update(struct rte_eth_dev *dev,
@@ -184,8 +188,10 @@ mlx5_dev_rss_reta_update(struct rte_eth_dev *dev,
 	unsigned int i;
 	unsigned int pos;
 
-	if (!reta_size)
-		return -EINVAL;
+	if (!reta_size) {
+		rte_errno = EINVAL;
+		return -rte_errno;
+	}
 	ret = mlx5_rss_reta_index_resize(dev, reta_size);
 	if (ret)
 		return ret;
@@ -199,7 +205,7 @@ mlx5_dev_rss_reta_update(struct rte_eth_dev *dev,
 	}
 	if (dev->data->dev_started) {
 		mlx5_dev_stop(dev);
-		mlx5_dev_start(dev);
+		return mlx5_dev_start(dev);
 	}
-	return -ret;
+	return 0;
 }
diff --git a/drivers/net/mlx5/mlx5_rxmode.c b/drivers/net/mlx5/mlx5_rxmode.c
index 4ffc869ad..0c1e9eb2a 100644
--- a/drivers/net/mlx5/mlx5_rxmode.c
+++ b/drivers/net/mlx5/mlx5_rxmode.c
@@ -32,8 +32,13 @@
 void
 mlx5_promiscuous_enable(struct rte_eth_dev *dev)
 {
+	int ret;
+
 	dev->data->promiscuous = 1;
-	mlx5_traffic_restart(dev);
+	ret = mlx5_traffic_restart(dev);
+	if (ret)
+		ERROR("%p cannot enable promiscuous mode: %s", (void *)dev,
+		      strerror(rte_errno));
 }
 
 /**
@@ -45,8 +50,13 @@ mlx5_promiscuous_enable(struct rte_eth_dev *dev)
 void
 mlx5_promiscuous_disable(struct rte_eth_dev *dev)
 {
+	int ret;
+
 	dev->data->promiscuous = 0;
-	mlx5_traffic_restart(dev);
+	ret = mlx5_traffic_restart(dev);
+	if (ret)
+		ERROR("%p cannot disable promiscuous mode: %s", (void *)dev,
+		      strerror(rte_errno));
 }
 
 /**
@@ -58,8 +68,13 @@ mlx5_promiscuous_disable(struct rte_eth_dev *dev)
 void
 mlx5_allmulticast_enable(struct rte_eth_dev *dev)
 {
+	int ret;
+
 	dev->data->all_multicast = 1;
-	mlx5_traffic_restart(dev);
+	ret = mlx5_traffic_restart(dev);
+	if (ret)
+		ERROR("%p cannot enable allmulicast mode: %s", (void *)dev,
+		      strerror(rte_errno));
 }
 
 /**
@@ -71,6 +86,11 @@ mlx5_allmulticast_enable(struct rte_eth_dev *dev)
 void
 mlx5_allmulticast_disable(struct rte_eth_dev *dev)
 {
+	int ret;
+
 	dev->data->all_multicast = 0;
-	mlx5_traffic_restart(dev);
+	ret = mlx5_traffic_restart(dev);
+	if (ret)
+		ERROR("%p cannot disable allmulicast mode: %s", (void *)dev,
+		      strerror(rte_errno));
 }
diff --git a/drivers/net/mlx5/mlx5_rxq.c b/drivers/net/mlx5/mlx5_rxq.c
index 8e7693df2..477aa2631 100644
--- a/drivers/net/mlx5/mlx5_rxq.c
+++ b/drivers/net/mlx5/mlx5_rxq.c
@@ -61,7 +61,7 @@ const size_t rss_hash_default_key_len = sizeof(rss_hash_default_key);
  *   Pointer to RX queue structure.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 rxq_alloc_elts(struct mlx5_rxq_ctrl *rxq_ctrl)
@@ -69,7 +69,7 @@ rxq_alloc_elts(struct mlx5_rxq_ctrl *rxq_ctrl)
 	const unsigned int sges_n = 1 << rxq_ctrl->rxq.sges_n;
 	unsigned int elts_n = 1 << rxq_ctrl->rxq.elts_n;
 	unsigned int i;
-	int ret = 0;
+	int err;
 
 	/* Iterate on segments. */
 	for (i = 0; (i != elts_n); ++i) {
@@ -78,7 +78,7 @@ rxq_alloc_elts(struct mlx5_rxq_ctrl *rxq_ctrl)
 		buf = rte_pktmbuf_alloc(rxq_ctrl->rxq.mp);
 		if (buf == NULL) {
 			ERROR("%p: empty mbuf pool", (void *)rxq_ctrl);
-			ret = ENOMEM;
+			rte_errno = ENOMEM;
 			goto error;
 		}
 		/* Headroom is reserved by rte_pktmbuf_alloc(). */
@@ -120,9 +120,9 @@ rxq_alloc_elts(struct mlx5_rxq_ctrl *rxq_ctrl)
 	}
 	DEBUG("%p: allocated and configured %u segments (max %u packets)",
 	      (void *)rxq_ctrl, elts_n, elts_n / (1 << rxq_ctrl->rxq.sges_n));
-	assert(ret == 0);
 	return 0;
 error:
+	err = rte_errno; /* Save rte_errno before cleanup. */
 	elts_n = i;
 	for (i = 0; (i != elts_n); ++i) {
 		if ((*rxq_ctrl->rxq.elts)[i] != NULL)
@@ -130,8 +130,8 @@ rxq_alloc_elts(struct mlx5_rxq_ctrl *rxq_ctrl)
 		(*rxq_ctrl->rxq.elts)[i] = NULL;
 	}
 	DEBUG("%p: failed, freed everything", (void *)rxq_ctrl);
-	assert(ret > 0);
-	return ret;
+	rte_errno = err; /* Restore rte_errno. */
+	return -rte_errno;
 }
 
 /**
@@ -271,7 +271,7 @@ mlx5_is_rx_queue_offloads_allowed(struct rte_eth_dev *dev, uint64_t offloads)
  *   Memory pool for buffer allocations.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
@@ -282,7 +282,6 @@ mlx5_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 	struct mlx5_rxq_data *rxq = (*priv->rxqs)[idx];
 	struct mlx5_rxq_ctrl *rxq_ctrl =
 		container_of(rxq, struct mlx5_rxq_ctrl, rxq);
-	int ret = 0;
 
 	if (!rte_is_power_of_2(desc)) {
 		desc = 1 << log2above(desc);
@@ -295,37 +294,37 @@ mlx5_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 	if (idx >= priv->rxqs_n) {
 		ERROR("%p: queue index out of range (%u >= %u)",
 		      (void *)dev, idx, priv->rxqs_n);
-		return -EOVERFLOW;
+		rte_errno = EOVERFLOW;
+		return -rte_errno;
 	}
 	if (!mlx5_is_rx_queue_offloads_allowed(dev, conf->offloads)) {
-		ret = ENOTSUP;
 		ERROR("%p: Rx queue offloads 0x%" PRIx64 " don't match port "
 		      "offloads 0x%" PRIx64 " or supported offloads 0x%" PRIx64,
 		      (void *)dev, conf->offloads,
 		      dev->data->dev_conf.rxmode.offloads,
 		      (mlx5_get_rx_port_offloads() |
 		       mlx5_get_rx_queue_offloads(dev)));
-		goto out;
+		rte_errno = ENOTSUP;
+		return -rte_errno;
 	}
 	if (!mlx5_rxq_releasable(dev, idx)) {
-		ret = EBUSY;
 		ERROR("%p: unable to release queue index %u",
 		      (void *)dev, idx);
-		goto out;
+		rte_errno = EBUSY;
+		return -rte_errno;
 	}
 	mlx5_rxq_release(dev, idx);
 	rxq_ctrl = mlx5_rxq_new(dev, idx, desc, socket, conf, mp);
 	if (!rxq_ctrl) {
 		ERROR("%p: unable to allocate queue index %u",
 		      (void *)dev, idx);
-		ret = ENOMEM;
-		goto out;
+		rte_errno = ENOMEM;
+		return -rte_errno;
 	}
 	DEBUG("%p: adding RX queue %p to list",
 	      (void *)dev, (void *)rxq_ctrl);
 	(*priv->rxqs)[idx] = &rxq_ctrl->rxq;
-out:
-	return -ret;
+	return 0;
 }
 
 /**
@@ -358,7 +357,7 @@ mlx5_rx_queue_release(void *dpdk_rxq)
  *   Pointer to Ethernet device.
  *
  * @return
- *   0 on success, negative on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_rx_intr_vec_enable(struct rte_eth_dev *dev)
@@ -377,7 +376,8 @@ mlx5_rx_intr_vec_enable(struct rte_eth_dev *dev)
 	if (intr_handle->intr_vec == NULL) {
 		ERROR("failed to allocate memory for interrupt vector,"
 		      " Rx interrupts will not be supported");
-		return -ENOMEM;
+		rte_errno = ENOMEM;
+		return -rte_errno;
 	}
 	intr_handle->type = RTE_INTR_HANDLE_EXT;
 	for (i = 0; i != n; ++i) {
@@ -400,16 +400,18 @@ mlx5_rx_intr_vec_enable(struct rte_eth_dev *dev)
 			      " (%d), Rx interrupts cannot be enabled",
 			      RTE_MAX_RXTX_INTR_VEC_ID);
 			mlx5_rx_intr_vec_disable(dev);
-			return -1;
+			rte_errno = ENOMEM;
+			return -rte_errno;
 		}
 		fd = rxq_ibv->channel->fd;
 		flags = fcntl(fd, F_GETFL);
 		rc = fcntl(fd, F_SETFL, flags | O_NONBLOCK);
 		if (rc < 0) {
+			rte_errno = errno;
 			ERROR("failed to make Rx interrupt file descriptor"
 			      " %d non-blocking for queue index %d", fd, i);
 			mlx5_rx_intr_vec_disable(dev);
-			return -1;
+			return -rte_errno;
 		}
 		intr_handle->intr_vec[i] = RTE_INTR_VEC_RXTX_OFFSET + count;
 		intr_handle->efds[count] = fd;
@@ -497,7 +499,7 @@ mlx5_arm_cq(struct mlx5_rxq_data *rxq, int sq_n_rxq)
  *   Rx queue number.
  *
  * @return
- *   0 on success, negative on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_rx_intr_enable(struct rte_eth_dev *dev, uint16_t rx_queue_id)
@@ -505,12 +507,11 @@ mlx5_rx_intr_enable(struct rte_eth_dev *dev, uint16_t rx_queue_id)
 	struct priv *priv = dev->data->dev_private;
 	struct mlx5_rxq_data *rxq_data;
 	struct mlx5_rxq_ctrl *rxq_ctrl;
-	int ret = 0;
 
 	rxq_data = (*priv->rxqs)[rx_queue_id];
 	if (!rxq_data) {
-		ret = EINVAL;
-		goto exit;
+		rte_errno = EINVAL;
+		return -rte_errno;
 	}
 	rxq_ctrl = container_of(rxq_data, struct mlx5_rxq_ctrl, rxq);
 	if (rxq_ctrl->irq) {
@@ -518,16 +519,13 @@ mlx5_rx_intr_enable(struct rte_eth_dev *dev, uint16_t rx_queue_id)
 
 		rxq_ibv = mlx5_rxq_ibv_get(dev, rx_queue_id);
 		if (!rxq_ibv) {
-			ret = EINVAL;
-			goto exit;
+			rte_errno = EINVAL;
+			return -rte_errno;
 		}
 		mlx5_arm_cq(rxq_data, rxq_data->cq_arm_sn);
 		mlx5_rxq_ibv_release(rxq_ibv);
 	}
-exit:
-	if (ret)
-		WARN("unable to arm interrupt on rx queue %d", rx_queue_id);
-	return -ret;
+	return 0;
 }
 
 /**
@@ -539,7 +537,7 @@ mlx5_rx_intr_enable(struct rte_eth_dev *dev, uint16_t rx_queue_id)
  *   Rx queue number.
  *
  * @return
- *   0 on success, negative on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_rx_intr_disable(struct rte_eth_dev *dev, uint16_t rx_queue_id)
@@ -550,35 +548,36 @@ mlx5_rx_intr_disable(struct rte_eth_dev *dev, uint16_t rx_queue_id)
 	struct mlx5_rxq_ibv *rxq_ibv = NULL;
 	struct ibv_cq *ev_cq;
 	void *ev_ctx;
-	int ret = 0;
+	int ret;
 
 	rxq_data = (*priv->rxqs)[rx_queue_id];
 	if (!rxq_data) {
-		ret = EINVAL;
-		goto exit;
+		rte_errno = EINVAL;
+		return -rte_errno;
 	}
 	rxq_ctrl = container_of(rxq_data, struct mlx5_rxq_ctrl, rxq);
 	if (!rxq_ctrl->irq)
-		goto exit;
+		return 0;
 	rxq_ibv = mlx5_rxq_ibv_get(dev, rx_queue_id);
 	if (!rxq_ibv) {
-		ret = EINVAL;
-		goto exit;
+		rte_errno = EINVAL;
+		return -rte_errno;
 	}
 	ret = mlx5_glue->get_cq_event(rxq_ibv->channel, &ev_cq, &ev_ctx);
 	if (ret || ev_cq != rxq_ibv->cq) {
-		ret = EINVAL;
+		rte_errno = EINVAL;
 		goto exit;
 	}
 	rxq_data->cq_arm_sn++;
 	mlx5_glue->ack_cq_events(rxq_ibv->cq, 1);
+	return 0;
 exit:
+	ret = rte_errno; /* Save rte_errno before cleanup. */
 	if (rxq_ibv)
 		mlx5_rxq_ibv_release(rxq_ibv);
-	if (ret)
-		WARN("unable to disable interrupt on rx queue %d",
-		     rx_queue_id);
-	return -ret;
+	WARN("unable to disable interrupt on rx queue %d", rx_queue_id);
+	rte_errno = ret; /* Restore rte_errno. */
+	return -rte_errno;
 }
 
 /**
@@ -590,7 +589,7 @@ mlx5_rx_intr_disable(struct rte_eth_dev *dev, uint16_t rx_queue_id)
  *   Queue index in DPDK Rx queue array
  *
  * @return
- *   The Verbs object initialised if it can be created.
+ *   The Verbs object initialised, NULL otherwise and rte_errno is set.
  */
 struct mlx5_rxq_ibv *
 mlx5_rxq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
@@ -626,6 +625,7 @@ mlx5_rxq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 	if (!tmpl) {
 		ERROR("%p: cannot allocate verbs resources",
 		       (void *)rxq_ctrl);
+		rte_errno = ENOMEM;
 		goto error;
 	}
 	tmpl->rxq_ctrl = rxq_ctrl;
@@ -643,6 +643,7 @@ mlx5_rxq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 		if (!tmpl->channel) {
 			ERROR("%p: Comp Channel creation failure",
 			      (void *)rxq_ctrl);
+			rte_errno = ENOMEM;
 			goto error;
 		}
 	}
@@ -672,6 +673,7 @@ mlx5_rxq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 					 &attr.cq.mlx5));
 	if (tmpl->cq == NULL) {
 		ERROR("%p: CQ creation failure", (void *)rxq_ctrl);
+		rte_errno = ENOMEM;
 		goto error;
 	}
 	DEBUG("priv->device_attr.max_qp_wr is %d",
@@ -708,6 +710,7 @@ mlx5_rxq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 	tmpl->wq = mlx5_glue->create_wq(priv->ctx, &attr.wq);
 	if (tmpl->wq == NULL) {
 		ERROR("%p: WQ creation failure", (void *)rxq_ctrl);
+		rte_errno = ENOMEM;
 		goto error;
 	}
 	/*
@@ -722,6 +725,7 @@ mlx5_rxq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 		      ((1 << rxq_data->elts_n) >> rxq_data->sges_n),
 		      (1 << rxq_data->sges_n),
 		      attr.wq.max_wr, attr.wq.max_sge);
+		rte_errno = EINVAL;
 		goto error;
 	}
 	/* Change queue state to ready. */
@@ -733,6 +737,7 @@ mlx5_rxq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 	if (ret) {
 		ERROR("%p: WQ state to IBV_WQS_RDY failed",
 		      (void *)rxq_ctrl);
+		rte_errno = ret;
 		goto error;
 	}
 	obj.cq.in = tmpl->cq;
@@ -740,11 +745,14 @@ mlx5_rxq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 	obj.rwq.in = tmpl->wq;
 	obj.rwq.out = &rwq;
 	ret = mlx5_glue->dv_init_obj(&obj, MLX5DV_OBJ_CQ | MLX5DV_OBJ_RWQ);
-	if (ret != 0)
+	if (ret) {
+		rte_errno = ret;
 		goto error;
+	}
 	if (cq_info.cqe_size != RTE_CACHE_LINE_SIZE) {
 		ERROR("Wrong MLX5_CQE_SIZE environment variable value: "
 		      "it should be set to %u", RTE_CACHE_LINE_SIZE);
+		rte_errno = EINVAL;
 		goto error;
 	}
 	/* Fill the rings. */
@@ -788,6 +796,7 @@ mlx5_rxq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 	priv->verbs_alloc_ctx.type = MLX5_VERBS_ALLOC_TYPE_NONE;
 	return tmpl;
 error:
+	ret = rte_errno; /* Save rte_errno before cleanup. */
 	if (tmpl->wq)
 		claim_zero(mlx5_glue->destroy_wq(tmpl->wq));
 	if (tmpl->cq)
@@ -797,6 +806,7 @@ mlx5_rxq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 	if (tmpl->mr)
 		mlx5_mr_release(tmpl->mr);
 	priv->verbs_alloc_ctx.type = MLX5_VERBS_ALLOC_TYPE_NONE;
+	rte_errno = ret; /* Restore rte_errno. */
 	return NULL;
 }
 
@@ -920,7 +930,7 @@ mlx5_rxq_ibv_releasable(struct mlx5_rxq_ibv *rxq_ibv)
  *   NUMA socket on which memory must be allocated.
  *
  * @return
- *   A DPDK queue object on success.
+ *   A DPDK queue object on success, NULL otherwise and rte_errno is set.
  */
 struct mlx5_rxq_ctrl *
 mlx5_rxq_new(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
@@ -942,8 +952,10 @@ mlx5_rxq_new(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 				 sizeof(*tmpl) +
 				 desc_n * sizeof(struct rte_mbuf *),
 				 0, socket);
-	if (!tmpl)
+	if (!tmpl) {
+		rte_errno = ENOMEM;
 		return NULL;
+	}
 	tmpl->socket = socket;
 	if (priv->dev->data->dev_conf.intr_conf.rxq)
 		tmpl->irq = 1;
@@ -973,6 +985,7 @@ mlx5_rxq_new(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 			      (void *)dev,
 			      1 << sges_n,
 			      dev->data->dev_conf.rxmode.max_rx_pkt_len);
+			rte_errno = EOVERFLOW;
 			goto error;
 		}
 	} else {
@@ -991,6 +1004,7 @@ mlx5_rxq_new(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 		      (void *)dev,
 		      desc,
 		      1 << tmpl->rxq.sges_n);
+		rte_errno = EINVAL;
 		goto error;
 	}
 	/* Toggle RX checksum offload if hardware supports it. */
@@ -1045,7 +1059,7 @@ mlx5_rxq_new(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
  *   TX queue index.
  *
  * @return
- *   A pointer to the queue if it exists.
+ *   A pointer to the queue if it exists, NULL otherwise.
  */
 struct mlx5_rxq_ctrl *
 mlx5_rxq_get(struct rte_eth_dev *dev, uint16_t idx)
@@ -1108,7 +1122,8 @@ mlx5_rxq_release(struct rte_eth_dev *dev, uint16_t idx)
  *   TX queue index.
  *
  * @return
- *   1 if the queue can be released.
+ *   1 if the queue can be released, negative errno otherwise and rte_errno is
+ *   set.
  */
 int
 mlx5_rxq_releasable(struct rte_eth_dev *dev, uint16_t idx)
@@ -1116,8 +1131,10 @@ mlx5_rxq_releasable(struct rte_eth_dev *dev, uint16_t idx)
 	struct priv *priv = dev->data->dev_private;
 	struct mlx5_rxq_ctrl *rxq_ctrl;
 
-	if (!(*priv->rxqs)[idx])
-		return -1;
+	if (!(*priv->rxqs)[idx]) {
+		rte_errno = EINVAL;
+		return -rte_errno;
+	}
 	rxq_ctrl = container_of((*priv->rxqs)[idx], struct mlx5_rxq_ctrl, rxq);
 	return (rte_atomic32_read(&rxq_ctrl->refcnt) == 1);
 }
@@ -1157,7 +1174,7 @@ mlx5_rxq_verify(struct rte_eth_dev *dev)
  *   Number of queues in the array.
  *
  * @return
- *   A new indirection table.
+ *   The Verbs object initialised, NULL otherwise and rte_errno is set.
  */
 struct mlx5_ind_table_ibv *
 mlx5_ind_table_ibv_new(struct rte_eth_dev *dev, uint16_t queues[],
@@ -1174,8 +1191,10 @@ mlx5_ind_table_ibv_new(struct rte_eth_dev *dev, uint16_t queues[],
 
 	ind_tbl = rte_calloc(__func__, 1, sizeof(*ind_tbl) +
 			     queues_n * sizeof(uint16_t), 0);
-	if (!ind_tbl)
+	if (!ind_tbl) {
+		rte_errno = ENOMEM;
 		return NULL;
+	}
 	for (i = 0; i != queues_n; ++i) {
 		struct mlx5_rxq_ctrl *rxq = mlx5_rxq_get(dev, queues[i]);
 
@@ -1195,8 +1214,10 @@ mlx5_ind_table_ibv_new(struct rte_eth_dev *dev, uint16_t queues[],
 			.ind_tbl = wq,
 			.comp_mask = 0,
 		 });
-	if (!ind_tbl->ind_table)
+	if (!ind_tbl->ind_table) {
+		rte_errno = errno;
 		goto error;
+	}
 	rte_atomic32_inc(&ind_tbl->refcnt);
 	LIST_INSERT_HEAD(&priv->ind_tbls, ind_tbl, next);
 	DEBUG("%p: Indirection table %p: refcnt %d", (void *)dev,
@@ -1321,7 +1342,7 @@ mlx5_ind_table_ibv_verify(struct rte_eth_dev *dev)
  *   Number of queues.
  *
  * @return
- *   An hash Rx queue on success.
+ *   The Verbs object initialised, NULL otherwise and rte_errno is set.
  */
 struct mlx5_hrxq *
 mlx5_hrxq_new(struct rte_eth_dev *dev, uint8_t *rss_key, uint8_t rss_key_len,
@@ -1331,13 +1352,16 @@ mlx5_hrxq_new(struct rte_eth_dev *dev, uint8_t *rss_key, uint8_t rss_key_len,
 	struct mlx5_hrxq *hrxq;
 	struct mlx5_ind_table_ibv *ind_tbl;
 	struct ibv_qp *qp;
+	int err;
 
 	queues_n = hash_fields ? queues_n : 1;
 	ind_tbl = mlx5_ind_table_ibv_get(dev, queues, queues_n);
 	if (!ind_tbl)
 		ind_tbl = mlx5_ind_table_ibv_new(dev, queues, queues_n);
-	if (!ind_tbl)
+	if (!ind_tbl) {
+		rte_errno = ENOMEM;
 		return NULL;
+	}
 	qp = mlx5_glue->create_qp_ex
 		(priv->ctx,
 		 &(struct ibv_qp_init_attr_ex){
@@ -1355,8 +1379,10 @@ mlx5_hrxq_new(struct rte_eth_dev *dev, uint8_t *rss_key, uint8_t rss_key_len,
 			.rwq_ind_tbl = ind_tbl->ind_table,
 			.pd = priv->pd,
 		 });
-	if (!qp)
+	if (!qp) {
+		rte_errno = errno;
 		goto error;
+	}
 	hrxq = rte_calloc(__func__, 1, sizeof(*hrxq) + rss_key_len, 0);
 	if (!hrxq)
 		goto error;
@@ -1371,9 +1397,11 @@ mlx5_hrxq_new(struct rte_eth_dev *dev, uint8_t *rss_key, uint8_t rss_key_len,
 	      (void *)hrxq, rte_atomic32_read(&hrxq->refcnt));
 	return hrxq;
 error:
+	err = rte_errno; /* Save rte_errno before cleanup. */
 	mlx5_ind_table_ibv_release(dev, ind_tbl);
 	if (qp)
 		claim_zero(mlx5_glue->destroy_qp(qp));
+	rte_errno = err; /* Restore rte_errno. */
 	return NULL;
 }
 
diff --git a/drivers/net/mlx5/mlx5_socket.c b/drivers/net/mlx5/mlx5_socket.c
index 8db25cff1..6e2d971c7 100644
--- a/drivers/net/mlx5/mlx5_socket.c
+++ b/drivers/net/mlx5/mlx5_socket.c
@@ -22,7 +22,7 @@
  *   Pointer to Ethernet device.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_socket_init(struct rte_eth_dev *dev)
@@ -41,16 +41,21 @@ mlx5_socket_init(struct rte_eth_dev *dev)
 	 */
 	ret = socket(AF_UNIX, SOCK_STREAM, 0);
 	if (ret < 0) {
+		rte_errno = errno;
 		WARN("secondary process not supported: %s", strerror(errno));
-		return ret;
+		goto error;
 	}
 	priv->primary_socket = ret;
 	flags = fcntl(priv->primary_socket, F_GETFL, 0);
-	if (flags == -1)
-		goto out;
+	if (flags == -1) {
+		rte_errno = errno;
+		goto error;
+	}
 	ret = fcntl(priv->primary_socket, F_SETFL, flags | O_NONBLOCK);
-	if (ret < 0)
-		goto out;
+	if (ret < 0) {
+		rte_errno = errno;
+		goto error;
+	}
 	snprintf(sun.sun_path, sizeof(sun.sun_path), "/var/tmp/%s_%d",
 		 MLX5_DRIVER_NAME, priv->primary_socket);
 	ret = stat(sun.sun_path, &file_stat);
@@ -59,29 +64,30 @@ mlx5_socket_init(struct rte_eth_dev *dev)
 	ret = bind(priv->primary_socket, (const struct sockaddr *)&sun,
 		   sizeof(sun));
 	if (ret < 0) {
+		rte_errno = errno;
 		WARN("cannot bind socket, secondary process not supported: %s",
 		     strerror(errno));
 		goto close;
 	}
 	ret = listen(priv->primary_socket, 0);
 	if (ret < 0) {
+		rte_errno = errno;
 		WARN("Secondary process not supported: %s", strerror(errno));
 		goto close;
 	}
-	return ret;
+	return 0;
 close:
 	remove(sun.sun_path);
-out:
+error:
 	claim_zero(close(priv->primary_socket));
 	priv->primary_socket = 0;
-	return -(ret);
+	return -rte_errno;
 }
 
 /**
  * Un-Initialise the socket to communicate with the secondary process
  *
  * @param[in] dev
- *   Pointer to Ethernet device.
  */
 void
 mlx5_socket_uninit(struct rte_eth_dev *dev)
@@ -131,19 +137,21 @@ mlx5_socket_handle(struct rte_eth_dev *dev)
 	ret = setsockopt(conn_sock, SOL_SOCKET, SO_PASSCRED, &(int){1},
 					 sizeof(int));
 	if (ret < 0) {
-		WARN("cannot change socket options");
-		goto out;
+		ret = errno;
+		WARN("cannot change socket options: %s", strerror(rte_errno));
+		goto error;
 	}
 	ret = recvmsg(conn_sock, &msg, MSG_WAITALL);
 	if (ret < 0) {
-		WARN("received an empty message: %s", strerror(errno));
-		goto out;
+		ret = errno;
+		WARN("received an empty message: %s", strerror(rte_errno));
+		goto error;
 	}
 	/* Expect to receive credentials only. */
 	cmsg = CMSG_FIRSTHDR(&msg);
 	if (cmsg == NULL) {
 		WARN("no message");
-		goto out;
+		goto error;
 	}
 	if ((cmsg->cmsg_type == SCM_CREDENTIALS) &&
 		(cmsg->cmsg_len >= sizeof(*cred))) {
@@ -153,13 +161,13 @@ mlx5_socket_handle(struct rte_eth_dev *dev)
 	cmsg = CMSG_NXTHDR(&msg, cmsg);
 	if (cmsg != NULL) {
 		WARN("Message wrongly formatted");
-		goto out;
+		goto error;
 	}
 	/* Make sure all the ancillary data was received and valid. */
 	if ((cred == NULL) || (cred->uid != getuid()) ||
 	    (cred->gid != getgid())) {
 		WARN("wrong credentials");
-		goto out;
+		goto error;
 	}
 	/* Set-up the ancillary data. */
 	cmsg = CMSG_FIRSTHDR(&msg);
@@ -172,7 +180,7 @@ mlx5_socket_handle(struct rte_eth_dev *dev)
 	ret = sendmsg(conn_sock, &msg, 0);
 	if (ret < 0)
 		WARN("cannot send response");
-out:
+error:
 	close(conn_sock);
 }
 
@@ -183,7 +191,7 @@ mlx5_socket_handle(struct rte_eth_dev *dev)
  *   Pointer to Ethernet structure.
  *
  * @return
- *   fd on success, negative errno value on failure.
+ *   fd on success, negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_socket_connect(struct rte_eth_dev *dev)
@@ -192,7 +200,7 @@ mlx5_socket_connect(struct rte_eth_dev *dev)
 	struct sockaddr_un sun = {
 		.sun_family = AF_UNIX,
 	};
-	int socket_fd;
+	int socket_fd = -1;
 	int *fd = NULL;
 	int ret;
 	struct ucred *cred;
@@ -212,57 +220,67 @@ mlx5_socket_connect(struct rte_eth_dev *dev)
 
 	ret = socket(AF_UNIX, SOCK_STREAM, 0);
 	if (ret < 0) {
+		rte_errno = errno;
 		WARN("cannot connect to primary");
-		return ret;
+		goto error;
 	}
 	socket_fd = ret;
 	snprintf(sun.sun_path, sizeof(sun.sun_path), "/var/tmp/%s_%d",
 		 MLX5_DRIVER_NAME, priv->primary_socket);
 	ret = connect(socket_fd, (const struct sockaddr *)&sun, sizeof(sun));
 	if (ret < 0) {
+		rte_errno = errno;
 		WARN("cannot connect to primary");
-		goto out;
+		goto error;
 	}
 	cmsg = CMSG_FIRSTHDR(&msg);
 	if (cmsg == NULL) {
+		rte_errno = EINVAL;
 		DEBUG("cannot get first message");
-		goto out;
+		goto error;
 	}
 	cmsg->cmsg_level = SOL_SOCKET;
 	cmsg->cmsg_type = SCM_CREDENTIALS;
 	cmsg->cmsg_len = CMSG_LEN(sizeof(*cred));
 	cred = (struct ucred *)CMSG_DATA(cmsg);
 	if (cred == NULL) {
+		rte_errno = EINVAL;
 		DEBUG("no credentials received");
-		goto out;
+		goto error;
 	}
 	cred->pid = getpid();
 	cred->uid = getuid();
 	cred->gid = getgid();
 	ret = sendmsg(socket_fd, &msg, MSG_DONTWAIT);
 	if (ret < 0) {
+		rte_errno = errno;
 		WARN("cannot send credentials to primary: %s",
 		     strerror(errno));
-		goto out;
+		goto error;
 	}
 	ret = recvmsg(socket_fd, &msg, MSG_WAITALL);
 	if (ret <= 0) {
+		rte_errno = errno;
 		WARN("no message from primary: %s", strerror(errno));
-		goto out;
+		goto error;
 	}
 	cmsg = CMSG_FIRSTHDR(&msg);
 	if (cmsg == NULL) {
+		rte_errno = EINVAL;
 		WARN("No file descriptor received");
-		goto out;
+		goto error;
 	}
 	fd = (int *)CMSG_DATA(cmsg);
-	if (*fd <= 0) {
+	if (*fd < 0) {
 		WARN("no file descriptor received: %s", strerror(errno));
-		ret = *fd;
-		goto out;
+		rte_errno = *fd;
+		goto error;
 	}
 	ret = *fd;
-out:
 	close(socket_fd);
-	return ret;
+	return 0;
+error:
+	if (socket_fd != -1)
+		close(socket_fd);
+	return -rte_errno;
 }
diff --git a/drivers/net/mlx5/mlx5_stats.c b/drivers/net/mlx5/mlx5_stats.c
index 0febed878..06e9a1f19 100644
--- a/drivers/net/mlx5/mlx5_stats.c
+++ b/drivers/net/mlx5/mlx5_stats.c
@@ -128,7 +128,8 @@ static const unsigned int xstats_n = RTE_DIM(mlx5_counters_init);
  *   Counters table output buffer.
  *
  * @return
- *   0 on success and stats is filled, negative on error.
+ *   0 on success and stats is filled, negative errno value otherwise and
+ *   rte_errno is set.
  */
 static int
 mlx5_read_dev_counters(struct rte_eth_dev *dev, uint64_t *stats)
@@ -140,13 +141,15 @@ mlx5_read_dev_counters(struct rte_eth_dev *dev, uint64_t *stats)
 	unsigned int stats_sz = xstats_ctrl->stats_n * sizeof(uint64_t);
 	unsigned char et_stat_buf[sizeof(struct ethtool_stats) + stats_sz];
 	struct ethtool_stats *et_stats = (struct ethtool_stats *)et_stat_buf;
+	int ret;
 
 	et_stats->cmd = ETHTOOL_GSTATS;
 	et_stats->n_stats = xstats_ctrl->stats_n;
 	ifr.ifr_data = (caddr_t)et_stats;
-	if (mlx5_ifreq(dev, SIOCETHTOOL, &ifr) != 0) {
+	ret = mlx5_ifreq(dev, SIOCETHTOOL, &ifr);
+	if (ret) {
 		WARN("unable to read statistic values from device");
-		return -1;
+		return ret;
 	}
 	for (i = 0; i != xstats_n; ++i) {
 		if (mlx5_counters_init[i].ib) {
@@ -178,18 +181,21 @@ mlx5_read_dev_counters(struct rte_eth_dev *dev, uint64_t *stats)
  *   Pointer to Ethernet device.
  *
  * @return
- *   Number of statistics on success, -1 on error.
+ *   Number of statistics on success, negative errno value otherwise and
+ *   rte_errno is set.
  */
 static int
 mlx5_ethtool_get_stats_n(struct rte_eth_dev *dev) {
 	struct ethtool_drvinfo drvinfo;
 	struct ifreq ifr;
+	int ret;
 
 	drvinfo.cmd = ETHTOOL_GDRVINFO;
 	ifr.ifr_data = (caddr_t)&drvinfo;
-	if (mlx5_ifreq(dev, SIOCETHTOOL, &ifr) != 0) {
+	ret = mlx5_ifreq(dev, SIOCETHTOOL, &ifr);
+	if (ret) {
 		WARN("unable to query number of statistics");
-		return -1;
+		return ret;
 	}
 	return drvinfo.n_stats;
 }
@@ -211,12 +217,14 @@ mlx5_xstats_init(struct rte_eth_dev *dev)
 	struct ethtool_gstrings *strings = NULL;
 	unsigned int dev_stats_n;
 	unsigned int str_sz;
+	int ret;
 
-	dev_stats_n = mlx5_ethtool_get_stats_n(dev);
-	if (dev_stats_n < 1) {
+	ret = mlx5_ethtool_get_stats_n(dev);
+	if (ret < 0) {
 		WARN("no extended statistics available");
 		return;
 	}
+	dev_stats_n = ret;
 	xstats_ctrl->stats_n = dev_stats_n;
 	/* Allocate memory to grab stat names and values. */
 	str_sz = dev_stats_n * ETH_GSTRING_LEN;
@@ -231,7 +239,8 @@ mlx5_xstats_init(struct rte_eth_dev *dev)
 	strings->string_set = ETH_SS_STATS;
 	strings->len = dev_stats_n;
 	ifr.ifr_data = (caddr_t)strings;
-	if (mlx5_ifreq(dev, SIOCETHTOOL, &ifr) != 0) {
+	ret = mlx5_ifreq(dev, SIOCETHTOOL, &ifr);
+	if (ret) {
 		WARN("unable to get statistic names");
 		goto free;
 	}
@@ -260,7 +269,9 @@ mlx5_xstats_init(struct rte_eth_dev *dev)
 	}
 	/* Copy to base at first time. */
 	assert(xstats_n <= MLX5_MAX_XSTATS);
-	mlx5_read_dev_counters(dev, xstats_ctrl->base);
+	ret = mlx5_read_dev_counters(dev, xstats_ctrl->base);
+	if (ret)
+		ERROR("cannot read device counters: %s", strerror(rte_errno));
 free:
 	rte_free(strings);
 }
@@ -277,7 +288,7 @@ mlx5_xstats_init(struct rte_eth_dev *dev)
  *
  * @return
  *   Number of extended stats on success and stats is filled,
- *   negative on error.
+ *   negative on error and rte_errno is set.
  */
 int
 mlx5_xstats_get(struct rte_eth_dev *dev, struct rte_eth_xstat *stats,
@@ -286,15 +297,15 @@ mlx5_xstats_get(struct rte_eth_dev *dev, struct rte_eth_xstat *stats,
 	struct priv *priv = dev->data->dev_private;
 	unsigned int i;
 	uint64_t counters[n];
-	int ret = 0;
 
 	if (n >= xstats_n && stats) {
 		struct mlx5_xstats_ctrl *xstats_ctrl = &priv->xstats_ctrl;
 		int stats_n;
+		int ret;
 
 		stats_n = mlx5_ethtool_get_stats_n(dev);
 		if (stats_n < 0)
-			return -1;
+			return stats_n;
 		if (xstats_ctrl->stats_n != stats_n)
 			mlx5_xstats_init(dev);
 		ret = mlx5_read_dev_counters(dev, counters);
@@ -315,6 +326,10 @@ mlx5_xstats_get(struct rte_eth_dev *dev, struct rte_eth_xstat *stats,
  *   Pointer to Ethernet device structure.
  * @param[out] stats
  *   Stats structure output buffer.
+ *
+ * @return
+ *   0 on success and stats is filled, negative errno value otherwise and
+ *   rte_errno is set.
  */
 int
 mlx5_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
@@ -419,14 +434,22 @@ mlx5_xstats_reset(struct rte_eth_dev *dev)
 	unsigned int i;
 	unsigned int n = xstats_n;
 	uint64_t counters[n];
+	int ret;
 
 	stats_n = mlx5_ethtool_get_stats_n(dev);
-	if (stats_n < 0)
+	if (stats_n < 0) {
+		ERROR("%p cannot get stats: %s", (void *)dev,
+		      strerror(-stats_n));
 		return;
+	}
 	if (xstats_ctrl->stats_n != stats_n)
 		mlx5_xstats_init(dev);
-	if (mlx5_read_dev_counters(dev, counters) < 0)
+	ret = mlx5_read_dev_counters(dev, counters);
+	if (ret) {
+		ERROR("%p cannot read device counters: %s", (void *)dev,
+		      strerror(rte_errno));
 		return;
+	}
 	for (i = 0; i != n; ++i)
 		xstats_ctrl->base[i] = counters[i];
 }
diff --git a/drivers/net/mlx5/mlx5_trigger.c b/drivers/net/mlx5/mlx5_trigger.c
index a3ccebdd6..4e396b7f0 100644
--- a/drivers/net/mlx5/mlx5_trigger.c
+++ b/drivers/net/mlx5/mlx5_trigger.c
@@ -37,14 +37,14 @@ mlx5_txq_stop(struct rte_eth_dev *dev)
  *   Pointer to Ethernet device structure.
  *
  * @return
- *   0 on success, errno on error.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_txq_start(struct rte_eth_dev *dev)
 {
 	struct priv *priv = dev->data->dev_private;
 	unsigned int i;
-	int ret = 0;
+	int ret;
 
 	/* Add memory regions to Tx queues. */
 	for (i = 0; i != priv->txqs_n; ++i) {
@@ -62,17 +62,19 @@ mlx5_txq_start(struct rte_eth_dev *dev)
 		txq_alloc_elts(txq_ctrl);
 		txq_ctrl->ibv = mlx5_txq_ibv_new(dev, i);
 		if (!txq_ctrl->ibv) {
-			ret = ENOMEM;
+			rte_errno = ENOMEM;
 			goto error;
 		}
 	}
 	ret = mlx5_tx_uar_remap(dev, priv->ctx->cmd_fd);
 	if (ret)
 		goto error;
-	return ret;
+	return 0;
 error:
+	ret = rte_errno; /* Save rte_errno before cleanup. */
 	mlx5_txq_stop(dev);
-	return ret;
+	rte_errno = ret; /* Restore rte_errno. */
+	return -rte_errno;
 }
 
 /**
@@ -98,7 +100,7 @@ mlx5_rxq_stop(struct rte_eth_dev *dev)
  *   Pointer to Ethernet device structure.
  *
  * @return
- *   0 on success, errno on error.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx5_rxq_start(struct rte_eth_dev *dev)
@@ -116,15 +118,15 @@ mlx5_rxq_start(struct rte_eth_dev *dev)
 		if (ret)
 			goto error;
 		rxq_ctrl->ibv = mlx5_rxq_ibv_new(dev, i);
-		if (!rxq_ctrl->ibv) {
-			ret = ENOMEM;
+		if (!rxq_ctrl->ibv)
 			goto error;
-		}
 	}
-	return -ret;
+	return 0;
 error:
+	ret = rte_errno; /* Save rte_errno before cleanup. */
 	mlx5_rxq_stop(dev);
-	return -ret;
+	rte_errno = ret; /* Restore rte_errno. */
+	return -rte_errno;
 }
 
 /**
@@ -136,48 +138,48 @@ mlx5_rxq_start(struct rte_eth_dev *dev)
  *   Pointer to Ethernet device structure.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_dev_start(struct rte_eth_dev *dev)
 {
 	struct priv *priv = dev->data->dev_private;
 	struct mlx5_mr *mr = NULL;
-	int err;
+	int ret;
 
 	dev->data->dev_started = 1;
-	err = mlx5_flow_create_drop_queue(dev);
-	if (err) {
+	ret = mlx5_flow_create_drop_queue(dev);
+	if (ret) {
 		ERROR("%p: Drop queue allocation failed: %s",
-		      (void *)dev, strerror(err));
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
 	DEBUG("%p: allocating and configuring hash RX queues", (void *)dev);
 	rte_mempool_walk(mlx5_mp2mr_iter, priv);
-	err = mlx5_txq_start(dev);
-	if (err) {
-		ERROR("%p: TXQ allocation failed: %s",
-		      (void *)dev, strerror(err));
+	ret = mlx5_txq_start(dev);
+	if (ret) {
+		ERROR("%p: Tx Queue allocation failed: %s",
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
-	err = mlx5_rxq_start(dev);
-	if (err) {
-		ERROR("%p: RXQ allocation failed: %s",
-		      (void *)dev, strerror(err));
+	ret = mlx5_rxq_start(dev);
+	if (ret) {
+		ERROR("%p: Rx Queue allocation failed: %s",
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
-	err = mlx5_rx_intr_vec_enable(dev);
-	if (err) {
-		ERROR("%p: RX interrupt vector creation failed",
-		      (void *)priv);
+	ret = mlx5_rx_intr_vec_enable(dev);
+	if (ret) {
+		ERROR("%p: Rx interrupt vector creation failed",
+		      (void *)dev);
 		goto error;
 	}
 	mlx5_xstats_init(dev);
 	/* Update link status and Tx/Rx callbacks for the first time. */
 	memset(&dev->data->dev_link, 0, sizeof(struct rte_eth_link));
 	INFO("Forcing port %u link to be up", dev->data->port_id);
-	err = mlx5_force_link_status_change(dev, ETH_LINK_UP);
-	if (err) {
+	ret = mlx5_force_link_status_change(dev, ETH_LINK_UP);
+	if (ret) {
 		DEBUG("Failed to set port %u link to be up",
 		      dev->data->port_id);
 		goto error;
@@ -185,6 +187,7 @@ mlx5_dev_start(struct rte_eth_dev *dev)
 	mlx5_dev_interrupt_handler_install(dev);
 	return 0;
 error:
+	ret = rte_errno; /* Save rte_errno before cleanup. */
 	/* Rollback. */
 	dev->data->dev_started = 0;
 	for (mr = LIST_FIRST(&priv->mr); mr; mr = LIST_FIRST(&priv->mr))
@@ -194,7 +197,8 @@ mlx5_dev_start(struct rte_eth_dev *dev)
 	mlx5_txq_stop(dev);
 	mlx5_rxq_stop(dev);
 	mlx5_flow_delete_drop_queue(dev);
-	return err;
+	rte_errno = ret; /* Restore rte_errno. */
+	return -rte_errno;
 }
 
 /**
@@ -238,7 +242,7 @@ mlx5_dev_stop(struct rte_eth_dev *dev)
  *   Pointer to Ethernet device structure.
  *
  * @return
- *   0 on success.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_traffic_enable(struct rte_eth_dev *dev)
@@ -276,8 +280,9 @@ mlx5_traffic_enable(struct rte_eth_dev *dev)
 			.type = 0,
 		};
 
-		claim_zero(mlx5_ctrl_flow(dev, &promisc, &promisc));
-		return 0;
+		ret = mlx5_ctrl_flow(dev, &promisc, &promisc);
+		if (ret)
+			goto error;
 	}
 	if (dev->data->all_multicast) {
 		struct rte_flow_item_eth multicast = {
@@ -286,7 +291,9 @@ mlx5_traffic_enable(struct rte_eth_dev *dev)
 			.type = 0,
 		};
 
-		claim_zero(mlx5_ctrl_flow(dev, &multicast, &multicast));
+		ret = mlx5_ctrl_flow(dev, &multicast, &multicast);
+		if (ret)
+			goto error;
 	} else {
 		/* Add broadcast/multicast flows. */
 		for (i = 0; i != vlan_filter_n; ++i) {
@@ -346,15 +353,17 @@ mlx5_traffic_enable(struct rte_eth_dev *dev)
 				goto error;
 		}
 		if (!vlan_filter_n) {
-			ret = mlx5_ctrl_flow(dev, &unicast,
-					     &unicast_mask);
+			ret = mlx5_ctrl_flow(dev, &unicast, &unicast_mask);
 			if (ret)
 				goto error;
 		}
 	}
 	return 0;
 error:
-	return rte_errno;
+	ret = rte_errno; /* Save rte_errno before cleanup. */
+	mlx5_flow_list_flush(dev, &priv->ctrl_flows);
+	rte_errno = ret; /* Restore rte_errno. */
+	return -rte_errno;
 }
 
 
@@ -379,14 +388,14 @@ mlx5_traffic_disable(struct rte_eth_dev *dev)
  *   Pointer to Ethernet device private data.
  *
  * @return
- *   0 on success.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_traffic_restart(struct rte_eth_dev *dev)
 {
 	if (dev->data->dev_started) {
 		mlx5_traffic_disable(dev);
-		mlx5_traffic_enable(dev);
+		return mlx5_traffic_enable(dev);
 	}
 	return 0;
 }
diff --git a/drivers/net/mlx5/mlx5_txq.c b/drivers/net/mlx5/mlx5_txq.c
index dbf743397..4719fdc21 100644
--- a/drivers/net/mlx5/mlx5_txq.c
+++ b/drivers/net/mlx5/mlx5_txq.c
@@ -161,7 +161,7 @@ mlx5_is_tx_queue_offloads_allowed(struct rte_eth_dev *dev, uint64_t offloads)
  *   Thresholds parameters.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_tx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
@@ -171,7 +171,6 @@ mlx5_tx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 	struct mlx5_txq_data *txq = (*priv->txqs)[idx];
 	struct mlx5_txq_ctrl *txq_ctrl =
 		container_of(txq, struct mlx5_txq_ctrl, txq);
-	int ret = 0;
 
 	/*
 	 * Don't verify port offloads for application which
@@ -179,13 +178,13 @@ mlx5_tx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 	 */
 	if (!!(conf->txq_flags & ETH_TXQ_FLAGS_IGNORE) &&
 	    !mlx5_is_tx_queue_offloads_allowed(dev, conf->offloads)) {
-		ret = ENOTSUP;
+		rte_errno = ENOTSUP;
 		ERROR("%p: Tx queue offloads 0x%" PRIx64 " don't match port "
 		      "offloads 0x%" PRIx64 " or supported offloads 0x%" PRIx64,
 		      (void *)dev, conf->offloads,
 		      dev->data->dev_conf.txmode.offloads,
 		      mlx5_get_tx_port_offloads(dev));
-		goto out;
+		return -rte_errno;
 	}
 	if (desc <= MLX5_TX_COMP_THRESH) {
 		WARN("%p: number of descriptors requested for TX queue %u"
@@ -205,27 +204,26 @@ mlx5_tx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 	if (idx >= priv->txqs_n) {
 		ERROR("%p: queue index out of range (%u >= %u)",
 		      (void *)dev, idx, priv->txqs_n);
-		return -EOVERFLOW;
+		rte_errno = EOVERFLOW;
+		return -rte_errno;
 	}
 	if (!mlx5_txq_releasable(dev, idx)) {
-		ret = EBUSY;
+		rte_errno = EBUSY;
 		ERROR("%p: unable to release queue index %u",
 		      (void *)dev, idx);
-		goto out;
+		return -rte_errno;
 	}
 	mlx5_txq_release(dev, idx);
 	txq_ctrl = mlx5_txq_new(dev, idx, desc, socket, conf);
 	if (!txq_ctrl) {
 		ERROR("%p: unable to allocate queue index %u",
 		      (void *)dev, idx);
-		ret = ENOMEM;
-		goto out;
+		return -rte_errno;
 	}
 	DEBUG("%p: adding TX queue %p to list",
 	      (void *)dev, (void *)txq_ctrl);
 	(*priv->txqs)[idx] = &txq_ctrl->txq;
-out:
-	return -ret;
+	return 0;
 }
 
 /**
@@ -248,9 +246,9 @@ mlx5_tx_queue_release(void *dpdk_txq)
 	priv = txq_ctrl->priv;
 	for (i = 0; (i != priv->txqs_n); ++i)
 		if ((*priv->txqs)[i] == txq) {
+			mlx5_txq_release(priv->dev, i);
 			DEBUG("%p: removing TX queue %p from list",
 			      (void *)priv->dev, (void *)txq_ctrl);
-			mlx5_txq_release(priv->dev, i);
 			break;
 		}
 }
@@ -267,7 +265,7 @@ mlx5_tx_queue_release(void *dpdk_txq)
  *   Verbs file descriptor to map UAR pages.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_tx_uar_remap(struct rte_eth_dev *dev, int fd)
@@ -284,7 +282,6 @@ mlx5_tx_uar_remap(struct rte_eth_dev *dev, int fd)
 	struct mlx5_txq_ctrl *txq_ctrl;
 	int already_mapped;
 	size_t page_size = sysconf(_SC_PAGESIZE);
-	int r;
 
 	memset(pages, 0, priv->txqs_n * sizeof(uintptr_t));
 	/*
@@ -323,8 +320,8 @@ mlx5_tx_uar_remap(struct rte_eth_dev *dev, int fd)
 				/* fixed mmap have to return same address */
 				ERROR("call to mmap failed on UAR for txq %d\n",
 				      i);
-				r = ENXIO;
-				return r;
+				rte_errno = ENXIO;
+				return -rte_errno;
 			}
 		}
 		if (rte_eal_process_type() == RTE_PROC_PRIMARY) /* save once */
@@ -364,7 +361,7 @@ is_empw_burst_func(eth_tx_burst_t tx_pkt_burst)
  *   Queue index in DPDK Rx queue array
  *
  * @return
- *   The Verbs object initialised if it can be created.
+ *   The Verbs object initialised, NULL otherwise and rte_errno is set.
  */
 struct mlx5_txq_ibv *
 mlx5_txq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
@@ -394,7 +391,8 @@ mlx5_txq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 	priv->verbs_alloc_ctx.obj = txq_ctrl;
 	if (mlx5_getenv_int("MLX5_ENABLE_CQE_COMPRESSION")) {
 		ERROR("MLX5_ENABLE_CQE_COMPRESSION must never be set");
-		goto error;
+		rte_errno = EINVAL;
+		return NULL;
 	}
 	memset(&tmpl, 0, sizeof(struct mlx5_txq_ibv));
 	/* MRs will be registered in mp2mr[] later. */
@@ -408,6 +406,7 @@ mlx5_txq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 	tmpl.cq = mlx5_glue->create_cq(priv->ctx, cqe_n, NULL, NULL, 0);
 	if (tmpl.cq == NULL) {
 		ERROR("%p: CQ creation failure", (void *)txq_ctrl);
+		rte_errno = errno;
 		goto error;
 	}
 	attr.init = (struct ibv_qp_init_attr_ex){
@@ -449,6 +448,7 @@ mlx5_txq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 	tmpl.qp = mlx5_glue->create_qp_ex(priv->ctx, &attr.init);
 	if (tmpl.qp == NULL) {
 		ERROR("%p: QP creation failure", (void *)txq_ctrl);
+		rte_errno = errno;
 		goto error;
 	}
 	attr.mod = (struct ibv_qp_attr){
@@ -461,6 +461,7 @@ mlx5_txq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 				   (IBV_QP_STATE | IBV_QP_PORT));
 	if (ret) {
 		ERROR("%p: QP state to IBV_QPS_INIT failed", (void *)txq_ctrl);
+		rte_errno = errno;
 		goto error;
 	}
 	attr.mod = (struct ibv_qp_attr){
@@ -469,18 +470,21 @@ mlx5_txq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 	ret = mlx5_glue->modify_qp(tmpl.qp, &attr.mod, IBV_QP_STATE);
 	if (ret) {
 		ERROR("%p: QP state to IBV_QPS_RTR failed", (void *)txq_ctrl);
+		rte_errno = errno;
 		goto error;
 	}
 	attr.mod.qp_state = IBV_QPS_RTS;
 	ret = mlx5_glue->modify_qp(tmpl.qp, &attr.mod, IBV_QP_STATE);
 	if (ret) {
 		ERROR("%p: QP state to IBV_QPS_RTS failed", (void *)txq_ctrl);
+		rte_errno = errno;
 		goto error;
 	}
 	txq_ibv = rte_calloc_socket(__func__, 1, sizeof(struct mlx5_txq_ibv), 0,
 				    txq_ctrl->socket);
 	if (!txq_ibv) {
 		ERROR("%p: cannot allocate memory", (void *)txq_ctrl);
+		rte_errno = ENOMEM;
 		goto error;
 	}
 	obj.cq.in = tmpl.cq;
@@ -488,11 +492,14 @@ mlx5_txq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 	obj.qp.in = tmpl.qp;
 	obj.qp.out = &qp;
 	ret = mlx5_glue->dv_init_obj(&obj, MLX5DV_OBJ_CQ | MLX5DV_OBJ_QP);
-	if (ret != 0)
+	if (ret != 0) {
+		rte_errno = errno;
 		goto error;
+	}
 	if (cq_info.cqe_size != RTE_CACHE_LINE_SIZE) {
 		ERROR("Wrong MLX5_CQE_SIZE environment variable value: "
 		      "it should be set to %u", RTE_CACHE_LINE_SIZE);
+		rte_errno = EINVAL;
 		goto error;
 	}
 	txq_data->cqe_n = log2above(cq_info.cqe_cnt);
@@ -518,6 +525,7 @@ mlx5_txq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 		txq_ctrl->uar_mmap_offset = qp.uar_mmap_offset;
 	} else {
 		ERROR("Failed to retrieve UAR info, invalid libmlx5.so version");
+		rte_errno = EINVAL;
 		goto error;
 	}
 	DEBUG("%p: Verbs Tx queue %p: refcnt %d", (void *)dev,
@@ -526,11 +534,13 @@ mlx5_txq_ibv_new(struct rte_eth_dev *dev, uint16_t idx)
 	priv->verbs_alloc_ctx.type = MLX5_VERBS_ALLOC_TYPE_NONE;
 	return txq_ibv;
 error:
+	ret = rte_errno; /* Save rte_errno before cleanup. */
 	if (tmpl.cq)
 		claim_zero(mlx5_glue->destroy_cq(tmpl.cq));
 	if (tmpl.qp)
 		claim_zero(mlx5_glue->destroy_qp(tmpl.qp));
 	priv->verbs_alloc_ctx.type = MLX5_VERBS_ALLOC_TYPE_NONE;
+	rte_errno = ret; /* Restore rte_errno. */
 	return NULL;
 }
 
@@ -743,7 +753,7 @@ txq_set_params(struct mlx5_txq_ctrl *txq_ctrl)
  *  Thresholds parameters.
  *
  * @return
- *   A DPDK queue object on success.
+ *   A DPDK queue object on success, NULL otherwise and rte_errno is set.
  */
 struct mlx5_txq_ctrl *
 mlx5_txq_new(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
@@ -756,8 +766,10 @@ mlx5_txq_new(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 				 sizeof(*tmpl) +
 				 desc * sizeof(struct rte_mbuf *),
 				 0, socket);
-	if (!tmpl)
+	if (!tmpl) {
+		rte_errno = ENOMEM;
 		return NULL;
+	}
 	assert(desc > MLX5_TX_COMP_THRESH);
 	tmpl->txq.offloads = conf->offloads;
 	tmpl->priv = priv;
diff --git a/drivers/net/mlx5/mlx5_vlan.c b/drivers/net/mlx5/mlx5_vlan.c
index 3df962a90..3246c0a38 100644
--- a/drivers/net/mlx5/mlx5_vlan.c
+++ b/drivers/net/mlx5/mlx5_vlan.c
@@ -37,14 +37,13 @@
  *   Toggle filter.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_vlan_filter_set(struct rte_eth_dev *dev, uint16_t vlan_id, int on)
 {
 	struct priv *priv = dev->data->dev_private;
 	unsigned int i;
-	int ret = 0;
 
 	DEBUG("%p: %s VLAN filter ID %" PRIu16,
 	      (void *)dev, (on ? "enable" : "disable"), vlan_id);
@@ -54,8 +53,8 @@ mlx5_vlan_filter_set(struct rte_eth_dev *dev, uint16_t vlan_id, int on)
 			break;
 	/* Check if there's room for another VLAN filter. */
 	if (i == RTE_DIM(priv->vlan_filter)) {
-		ret = -ENOMEM;
-		goto out;
+		rte_errno = ENOMEM;
+		return -rte_errno;
 	}
 	if (i < priv->vlan_filter_n) {
 		assert(priv->vlan_filter_n != 0);
@@ -78,10 +77,10 @@ mlx5_vlan_filter_set(struct rte_eth_dev *dev, uint16_t vlan_id, int on)
 		priv->vlan_filter[priv->vlan_filter_n] = vlan_id;
 		++priv->vlan_filter_n;
 	}
-	if (dev->data->dev_started)
-		mlx5_traffic_restart(dev);
 out:
-	return ret;
+	if (dev->data->dev_started)
+		return mlx5_traffic_restart(dev);
+	return 0;
 }
 
 /**
@@ -105,7 +104,7 @@ mlx5_vlan_strip_queue_set(struct rte_eth_dev *dev, uint16_t queue, int on)
 	uint16_t vlan_offloads =
 		(on ? IBV_WQ_FLAGS_CVLAN_STRIPPING : 0) |
 		0;
-	int err;
+	int ret;
 
 	/* Validate hw support */
 	if (!priv->config.hw_vlan_strip) {
@@ -129,10 +128,10 @@ mlx5_vlan_strip_queue_set(struct rte_eth_dev *dev, uint16_t queue, int on)
 		.flags_mask = IBV_WQ_FLAGS_CVLAN_STRIPPING,
 		.flags = vlan_offloads,
 	};
-	err = mlx5_glue->modify_wq(rxq_ctrl->ibv->wq, &mod);
-	if (err) {
+	ret = mlx5_glue->modify_wq(rxq_ctrl->ibv->wq, &mod);
+	if (ret) {
 		ERROR("%p: failed to modified stripping mode: %s",
-		      (void *)dev, strerror(err));
+		      (void *)dev, strerror(rte_errno));
 		return;
 	}
 	/* Update related bits in RX queue. */
@@ -146,6 +145,9 @@ mlx5_vlan_strip_queue_set(struct rte_eth_dev *dev, uint16_t queue, int on)
  *   Pointer to Ethernet device structure.
  * @param mask
  *   VLAN offload bit mask.
+ *
+ * @return
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
 int
 mlx5_vlan_offload_set(struct rte_eth_dev *dev, int mask)
