[dpdk-dev] [PATCH v1 27/48] net/mlx4: standardize on negative errno values

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

Due to its reliance on system calls, the mlx4 PMD uses positive errno
values internally and negative ones at the ethdev API border. Although most
internal functions are documented, this mixed design is unusual and prone
to mistakes (e.g. flow API implementation uses negative values
exclusively).

Standardize on negative errno values and rely on rte_errno instead of
errno in all functions.

Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
---
 drivers/net/mlx4/mlx4.c | 485 ++++++++++++++++++++++++-------------------
 1 file changed, 274 insertions(+), 211 deletions(-)

diff --git a/drivers/net/mlx4/mlx4.c b/drivers/net/mlx4/mlx4.c
index 7312482..8cfeab2 100644
--- a/drivers/net/mlx4/mlx4.c
+++ b/drivers/net/mlx4/mlx4.c
@@ -159,7 +159,7 @@ void priv_unlock(struct priv *priv)
  *   Interface name output buffer.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_get_ifname(const struct priv *priv, char (*ifname)[IF_NAMESIZE])
@@ -174,8 +174,10 @@ priv_get_ifname(const struct priv *priv, char (*ifname)[IF_NAMESIZE])
 		MKSTR(path, "%s/device/net", priv->ctx->device->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;
@@ -225,8 +227,10 @@ priv_get_ifname(const struct priv *priv, char (*ifname)[IF_NAMESIZE])
 			snprintf(match, sizeof(match), "%s", name);
 	}
 	closedir(dir);
-	if (match[0] == '\0')
-		return -1;
+	if (match[0] == '\0') {
+		rte_errno = ENODEV;
+		return -rte_errno;
+	}
 	strncpy(*ifname, match, sizeof(*ifname));
 	return 0;
 }
@@ -244,7 +248,8 @@ priv_get_ifname(const struct priv *priv, char (*ifname)[IF_NAMESIZE])
  *   Buffer size.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   Number of bytes read on success, negative errno value otherwise and
+ *   rte_errno is set.
  */
 static int
 priv_sysfs_read(const struct priv *priv, const char *entry,
@@ -253,25 +258,27 @@ priv_sysfs_read(const struct priv *priv, const char *entry,
 	char ifname[IF_NAMESIZE];
 	FILE *file;
 	int ret;
-	int err;
 
-	if (priv_get_ifname(priv, &ifname))
-		return -1;
+	ret = priv_get_ifname(priv, &ifname);
+	if (ret)
+		return ret;
 
 	MKSTR(path, "%s/device/net/%s/%s", priv->ctx->device->ibdev_path,
 	      ifname, entry);
 
 	file = fopen(path, "rb");
-	if (file == NULL)
-		return -1;
+	if (file == NULL) {
+		rte_errno = errno;
+		return -rte_errno;
+	}
 	ret = fread(buf, 1, size, file);
-	err = errno;
-	if (((size_t)ret < size) && (ferror(file)))
-		ret = -1;
-	else
+	if ((size_t)ret < size && ferror(file)) {
+		rte_errno = EIO;
+		ret = -rte_errno;
+	} else {
 		ret = size;
+	}
 	fclose(file);
-	errno = err;
 	return ret;
 }
 
@@ -288,7 +295,8 @@ priv_sysfs_read(const struct priv *priv, const char *entry,
  *   Buffer size.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   Number of bytes written on success, negative errno value otherwise and
+ *   rte_errno is set.
  */
 static int
 priv_sysfs_write(const struct priv *priv, const char *entry,
@@ -297,25 +305,27 @@ priv_sysfs_write(const struct priv *priv, const char *entry,
 	char ifname[IF_NAMESIZE];
 	FILE *file;
 	int ret;
-	int err;
 
-	if (priv_get_ifname(priv, &ifname))
-		return -1;
+	ret = priv_get_ifname(priv, &ifname);
+	if (ret)
+		return ret;
 
 	MKSTR(path, "%s/device/net/%s/%s", priv->ctx->device->ibdev_path,
 	      ifname, entry);
 
 	file = fopen(path, "wb");
-	if (file == NULL)
-		return -1;
+	if (file == NULL) {
+		rte_errno = errno;
+		return -rte_errno;
+	}
 	ret = fwrite(buf, 1, size, file);
-	err = errno;
-	if (((size_t)ret < size) || (ferror(file)))
-		ret = -1;
-	else
+	if ((size_t)ret < size || ferror(file)) {
+		rte_errno = EIO;
+		ret = -rte_errno;
+	} else {
 		ret = size;
+	}
 	fclose(file);
-	errno = err;
 	return ret;
 }
 
@@ -330,7 +340,7 @@ priv_sysfs_write(const struct priv *priv, const char *entry,
  *   Value output buffer.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_get_sysfs_ulong(struct priv *priv, const char *name, unsigned long *value)
@@ -340,18 +350,19 @@ priv_get_sysfs_ulong(struct priv *priv, const char *name, unsigned long *value)
 	char value_str[32];
 
 	ret = priv_sysfs_read(priv, name, value_str, (sizeof(value_str) - 1));
-	if (ret == -1) {
+	if (ret < 0) {
 		DEBUG("cannot read %s value from sysfs: %s",
-		      name, strerror(errno));
-		return -1;
+		      name, strerror(rte_errno));
+		return ret;
 	}
 	value_str[ret] = '\0';
 	errno = 0;
 	value_ret = strtoul(value_str, NULL, 0);
 	if (errno) {
+		rte_errno = errno;
 		DEBUG("invalid %s value `%s': %s", name, value_str,
-		      strerror(errno));
-		return -1;
+		      strerror(rte_errno));
+		return -rte_errno;
 	}
 	*value = value_ret;
 	return 0;
@@ -368,7 +379,7 @@ priv_get_sysfs_ulong(struct priv *priv, const char *name, unsigned long *value)
  *   Value to set.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_set_sysfs_ulong(struct priv *priv, const char *name, unsigned long value)
@@ -377,10 +388,10 @@ priv_set_sysfs_ulong(struct priv *priv, const char *name, unsigned long value)
 	MKSTR(value_str, "%lu", value);
 
 	ret = priv_sysfs_write(priv, name, value_str, (sizeof(value_str) - 1));
-	if (ret == -1) {
+	if (ret < 0) {
 		DEBUG("cannot write %s `%s' (%lu) to sysfs: %s",
-		      name, value_str, value, strerror(errno));
-		return -1;
+		      name, value_str, value, strerror(rte_errno));
+		return ret;
 	}
 	return 0;
 }
@@ -396,18 +407,23 @@ priv_set_sysfs_ulong(struct priv *priv, const char *name, unsigned long value)
  *   Interface request structure output buffer.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_ifreq(const struct priv *priv, int req, struct ifreq *ifr)
 {
 	int sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
-	int ret = -1;
+	int ret;
 
-	if (sock == -1)
-		return ret;
-	if (priv_get_ifname(priv, &ifr->ifr_name) == 0)
-		ret = ioctl(sock, req, ifr);
+	if (sock == -1) {
+		rte_errno = errno;
+		return -rte_errno;
+	}
+	ret = priv_get_ifname(priv, &ifr->ifr_name);
+	if (!ret && ioctl(sock, req, ifr) == -1) {
+		rte_errno = errno;
+		ret = -rte_errno;
+	}
 	close(sock);
 	return ret;
 }
@@ -421,15 +437,16 @@ priv_ifreq(const struct priv *priv, int req, struct ifreq *ifr)
  *   MTU value output buffer.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_get_mtu(struct priv *priv, uint16_t *mtu)
 {
-	unsigned long ulong_mtu;
+	unsigned long ulong_mtu = 0;
+	int ret = priv_get_sysfs_ulong(priv, "mtu", &ulong_mtu);
 
-	if (priv_get_sysfs_ulong(priv, "mtu", &ulong_mtu) == -1)
-		return -1;
+	if (ret)
+		return ret;
 	*mtu = ulong_mtu;
 	return 0;
 }
@@ -443,20 +460,23 @@ priv_get_mtu(struct priv *priv, uint16_t *mtu)
  *   MTU value to set.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_set_mtu(struct priv *priv, uint16_t mtu)
 {
 	uint16_t new_mtu;
+	int ret = priv_set_sysfs_ulong(priv, "mtu", mtu);
 
-	if (priv_set_sysfs_ulong(priv, "mtu", mtu) ||
-	    priv_get_mtu(priv, &new_mtu))
-		return -1;
+	if (ret)
+		return ret;
+	ret = priv_get_mtu(priv, &new_mtu);
+	if (ret)
+		return ret;
 	if (new_mtu == mtu)
 		return 0;
-	errno = EINVAL;
-	return -1;
+	rte_errno = EINVAL;
+	return -rte_errno;
 }
 
 /**
@@ -470,15 +490,16 @@ priv_set_mtu(struct priv *priv, uint16_t mtu)
  *   Bitmask for flags to modify.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_set_flags(struct priv *priv, unsigned int keep, unsigned int flags)
 {
-	unsigned long tmp;
+	unsigned long tmp = 0;
+	int ret = priv_get_sysfs_ulong(priv, "flags", &tmp);
 
-	if (priv_get_sysfs_ulong(priv, "flags", &tmp) == -1)
-		return -1;
+	if (ret)
+		return ret;
 	tmp &= keep;
 	tmp |= (flags & (~keep));
 	return priv_set_sysfs_ulong(priv, "flags", tmp);
@@ -513,7 +534,7 @@ priv_mac_addr_del(struct priv *priv);
  *   Pointer to Ethernet device structure.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 dev_configure(struct rte_eth_dev *dev)
@@ -544,7 +565,7 @@ dev_configure(struct rte_eth_dev *dev)
  *   Pointer to Ethernet device structure.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_dev_configure(struct rte_eth_dev *dev)
@@ -554,9 +575,8 @@ mlx4_dev_configure(struct rte_eth_dev *dev)
 
 	priv_lock(priv);
 	ret = dev_configure(dev);
-	assert(ret >= 0);
 	priv_unlock(priv);
-	return -ret;
+	return ret;
 }
 
 static uint16_t mlx4_tx_burst(void *, struct rte_mbuf **, uint16_t);
@@ -573,7 +593,7 @@ static uint16_t removed_rx_burst(void *, struct rte_mbuf **, uint16_t);
  *   Number of elements to allocate.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 txq_alloc_elts(struct txq *txq, unsigned int elts_n)
@@ -612,7 +632,8 @@ txq_alloc_elts(struct txq *txq, unsigned int elts_n)
 
 	DEBUG("%p: failed, freed everything", (void *)txq);
 	assert(ret > 0);
-	return ret;
+	rte_errno = ret;
+	return -rte_errno;
 }
 
 /**
@@ -806,7 +827,7 @@ static struct ibv_mr *mlx4_mp2mr(struct ibv_pd *, struct rte_mempool *)
  *   Pointer to memory pool.
  *
  * @return
- *   Memory region pointer, NULL in case of error.
+ *   Memory region pointer, NULL in case of error and rte_errno is set.
  */
 static struct ibv_mr *
 mlx4_mp2mr(struct ibv_pd *pd, struct rte_mempool *mp)
@@ -815,8 +836,10 @@ mlx4_mp2mr(struct ibv_pd *pd, struct rte_mempool *mp)
 	uintptr_t start;
 	uintptr_t end;
 	unsigned int i;
+	struct ibv_mr *mr;
 
 	if (mlx4_check_mempool(mp, &start, &end) != 0) {
+		rte_errno = EINVAL;
 		ERROR("mempool %p: not virtually contiguous",
 			(void *)mp);
 		return NULL;
@@ -839,10 +862,13 @@ mlx4_mp2mr(struct ibv_pd *pd, struct rte_mempool *mp)
 	DEBUG("mempool %p using start=%p end=%p size=%zu for MR",
 	      (void *)mp, (void *)start, (void *)end,
 	      (size_t)(end - start));
-	return ibv_reg_mr(pd,
-			  (void *)start,
-			  end - start,
-			  IBV_ACCESS_LOCAL_WRITE);
+	mr = ibv_reg_mr(pd,
+			(void *)start,
+			end - start,
+			IBV_ACCESS_LOCAL_WRITE);
+	if (!mr)
+		rte_errno = errno ? errno : EINVAL;
+	return mr;
 }
 
 /**
@@ -1155,7 +1181,7 @@ mlx4_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
  *   Thresholds parameters.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 txq_setup(struct rte_eth_dev *dev, struct txq *txq, uint16_t desc,
@@ -1170,21 +1196,24 @@ txq_setup(struct rte_eth_dev *dev, struct txq *txq, uint16_t desc,
 		struct ibv_qp_init_attr init;
 		struct ibv_qp_attr mod;
 	} attr;
-	int ret = 0;
+	int ret;
 
 	(void)conf; /* Thresholds configuration (ignored). */
-	if (priv == NULL)
-		return EINVAL;
+	if (priv == NULL) {
+		rte_errno = EINVAL;
+		goto error;
+	}
 	if (desc == 0) {
+		rte_errno = EINVAL;
 		ERROR("%p: invalid number of TX descriptors", (void *)dev);
-		return EINVAL;
+		goto error;
 	}
 	/* MRs will be registered in mp2mr[] later. */
 	tmpl.cq = ibv_create_cq(priv->ctx, desc, NULL, NULL, 0);
 	if (tmpl.cq == NULL) {
-		ret = ENOMEM;
+		rte_errno = ENOMEM;
 		ERROR("%p: CQ creation failure: %s",
-		      (void *)dev, strerror(ret));
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
 	DEBUG("priv->device_attr.max_qp_wr is %d",
@@ -1212,9 +1241,9 @@ txq_setup(struct rte_eth_dev *dev, struct txq *txq, uint16_t desc,
 	};
 	tmpl.qp = ibv_create_qp(priv->pd, &attr.init);
 	if (tmpl.qp == NULL) {
-		ret = (errno ? errno : EINVAL);
+		rte_errno = errno ? errno : EINVAL;
 		ERROR("%p: QP creation failure: %s",
-		      (void *)dev, strerror(ret));
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
 	/* ibv_create_qp() updates this value. */
@@ -1227,14 +1256,16 @@ txq_setup(struct rte_eth_dev *dev, struct txq *txq, uint16_t desc,
 	};
 	ret = ibv_modify_qp(tmpl.qp, &attr.mod, IBV_QP_STATE | IBV_QP_PORT);
 	if (ret) {
+		rte_errno = ret;
 		ERROR("%p: QP state to IBV_QPS_INIT failed: %s",
-		      (void *)dev, strerror(ret));
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
 	ret = txq_alloc_elts(&tmpl, desc);
 	if (ret) {
+		rte_errno = ret;
 		ERROR("%p: TXQ allocation failed: %s",
-		      (void *)dev, strerror(ret));
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
 	attr.mod = (struct ibv_qp_attr){
@@ -1242,15 +1273,17 @@ txq_setup(struct rte_eth_dev *dev, struct txq *txq, uint16_t desc,
 	};
 	ret = ibv_modify_qp(tmpl.qp, &attr.mod, IBV_QP_STATE);
 	if (ret) {
+		rte_errno = ret;
 		ERROR("%p: QP state to IBV_QPS_RTR failed: %s",
-		      (void *)dev, strerror(ret));
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
 	attr.mod.qp_state = IBV_QPS_RTS;
 	ret = ibv_modify_qp(tmpl.qp, &attr.mod, IBV_QP_STATE);
 	if (ret) {
+		rte_errno = ret;
 		ERROR("%p: QP state to IBV_QPS_RTS failed: %s",
-		      (void *)dev, strerror(ret));
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
 	/* Clean up txq in case we're reinitializing it. */
@@ -1260,12 +1293,13 @@ txq_setup(struct rte_eth_dev *dev, struct txq *txq, uint16_t desc,
 	DEBUG("%p: txq updated with %p", (void *)txq, (void *)&tmpl);
 	/* Pre-register known mempools. */
 	rte_mempool_walk(txq_mp2mr_iter, txq);
-	assert(ret == 0);
 	return 0;
 error:
+	ret = rte_errno;
 	txq_cleanup(&tmpl);
-	assert(ret > 0);
-	return ret;
+	rte_errno = ret;
+	assert(rte_errno > 0);
+	return -rte_errno;
 }
 
 /**
@@ -1283,7 +1317,7 @@ txq_setup(struct rte_eth_dev *dev, struct txq *txq, uint16_t desc,
  *   Thresholds parameters.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_tx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
@@ -1297,27 +1331,30 @@ mlx4_tx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 	DEBUG("%p: configuring queue %u for %u descriptors",
 	      (void *)dev, idx, desc);
 	if (idx >= priv->txqs_n) {
+		rte_errno = EOVERFLOW;
 		ERROR("%p: queue index out of range (%u >= %u)",
 		      (void *)dev, idx, priv->txqs_n);
 		priv_unlock(priv);
-		return -EOVERFLOW;
+		return -rte_errno;
 	}
 	if (txq != NULL) {
 		DEBUG("%p: reusing already allocated queue index %u (%p)",
 		      (void *)dev, idx, (void *)txq);
 		if (priv->started) {
+			rte_errno = EEXIST;
 			priv_unlock(priv);
-			return -EEXIST;
+			return -rte_errno;
 		}
 		(*priv->txqs)[idx] = NULL;
 		txq_cleanup(txq);
 	} else {
 		txq = rte_calloc_socket("TXQ", 1, sizeof(*txq), 0, socket);
 		if (txq == NULL) {
+			rte_errno = ENOMEM;
 			ERROR("%p: unable to allocate queue index %u",
 			      (void *)dev, idx);
 			priv_unlock(priv);
-			return -ENOMEM;
+			return -rte_errno;
 		}
 	}
 	ret = txq_setup(dev, txq, desc, socket, conf);
@@ -1332,7 +1369,7 @@ mlx4_tx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 		dev->tx_pkt_burst = mlx4_tx_burst;
 	}
 	priv_unlock(priv);
-	return -ret;
+	return ret;
 }
 
 /**
@@ -1378,7 +1415,7 @@ mlx4_tx_queue_release(void *dpdk_txq)
  *   with rte_pktmbuf_alloc().
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 rxq_alloc_elts(struct rxq *rxq, unsigned int elts_n, struct rte_mbuf **pool)
@@ -1387,11 +1424,10 @@ rxq_alloc_elts(struct rxq *rxq, unsigned int elts_n, struct rte_mbuf **pool)
 	struct rxq_elt (*elts)[elts_n] =
 		rte_calloc_socket("RXQ elements", 1, sizeof(*elts), 0,
 				  rxq->socket);
-	int ret = 0;
 
 	if (elts == NULL) {
+		rte_errno = ENOMEM;
 		ERROR("%p: can't allocate packets array", (void *)rxq);
-		ret = ENOMEM;
 		goto error;
 	}
 	/* For each WR (packet). */
@@ -1408,9 +1444,9 @@ rxq_alloc_elts(struct rxq *rxq, unsigned int elts_n, struct rte_mbuf **pool)
 		} else
 			buf = rte_pktmbuf_alloc(rxq->mp);
 		if (buf == NULL) {
+			rte_errno = ENOMEM;
 			assert(pool == NULL);
 			ERROR("%p: empty mbuf pool", (void *)rxq);
-			ret = ENOMEM;
 			goto error;
 		}
 		/* Configure WR. Work request ID contains its own index in
@@ -1442,11 +1478,11 @@ rxq_alloc_elts(struct rxq *rxq, unsigned int elts_n, struct rte_mbuf **pool)
 		if ((WR_ID(wr->wr_id).id != i) ||
 		    ((void *)((uintptr_t)sge->addr -
 			WR_ID(wr->wr_id).offset) != buf)) {
+			rte_errno = EOVERFLOW;
 			ERROR("%p: cannot store index and offset in WR ID",
 			      (void *)rxq);
 			sge->addr = 0;
 			rte_pktmbuf_free(buf);
-			ret = EOVERFLOW;
 			goto error;
 		}
 	}
@@ -1457,7 +1493,6 @@ rxq_alloc_elts(struct rxq *rxq, unsigned int elts_n, struct rte_mbuf **pool)
 	rxq->elts_n = elts_n;
 	rxq->elts_head = 0;
 	rxq->elts = elts;
-	assert(ret == 0);
 	return 0;
 error:
 	if (elts != NULL) {
@@ -1476,8 +1511,8 @@ rxq_alloc_elts(struct rxq *rxq, unsigned int elts_n, struct rte_mbuf **pool)
 		rte_free(elts);
 	}
 	DEBUG("%p: failed, freed everything", (void *)rxq);
-	assert(ret > 0);
-	return ret;
+	assert(rte_errno > 0);
+	return -rte_errno;
 }
 
 /**
@@ -1543,7 +1578,7 @@ priv_mac_addr_del(struct priv *priv)
  *   Pointer to private structure.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_mac_addr_add(struct priv *priv)
@@ -1601,16 +1636,12 @@ priv_mac_addr_add(struct priv *priv)
 	      (void *)priv,
 	      (*mac)[0], (*mac)[1], (*mac)[2], (*mac)[3], (*mac)[4], (*mac)[5]);
 	/* Create related flow. */
-	errno = 0;
 	flow = ibv_create_flow(rxq->qp, attr);
 	if (flow == NULL) {
-		/* It's not clear whether errno is always set in this case. */
+		rte_errno = errno ? errno : EINVAL;
 		ERROR("%p: flow configuration failed, errno=%d: %s",
-		      (void *)rxq, errno,
-		      (errno ? strerror(errno) : "Unknown error"));
-		if (errno)
-			return errno;
-		return EINVAL;
+		      (void *)rxq, rte_errno, strerror(errno));
+		return -rte_errno;
 	}
 	assert(priv->mac_flow == NULL);
 	priv->mac_flow = flow;
@@ -1791,11 +1822,12 @@ mlx4_rx_burst(void *dpdk_rxq, struct rte_mbuf **pkts, uint16_t pkts_n)
  *   Number of descriptors in QP (hint only).
  *
  * @return
- *   QP pointer or NULL in case of error.
+ *   QP pointer or NULL in case of error and rte_errno is set.
  */
 static struct ibv_qp *
 rxq_setup_qp(struct priv *priv, struct ibv_cq *cq, uint16_t desc)
 {
+	struct ibv_qp *qp;
 	struct ibv_qp_init_attr attr = {
 		/* CQ to be associated with the send queue. */
 		.send_cq = cq,
@@ -1812,7 +1844,10 @@ rxq_setup_qp(struct priv *priv, struct ibv_cq *cq, uint16_t desc)
 		.qp_type = IBV_QPT_RAW_PACKET,
 	};
 
-	return ibv_create_qp(priv->pd, &attr);
+	qp = ibv_create_qp(priv->pd, &attr);
+	if (!qp)
+		rte_errno = errno ? errno : EINVAL;
+	return qp;
 }
 
 /**
@@ -1832,7 +1867,7 @@ rxq_setup_qp(struct priv *priv, struct ibv_cq *cq, uint16_t desc)
  *   Memory pool for buffer allocations.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 rxq_setup(struct rte_eth_dev *dev, struct rxq *rxq, uint16_t desc,
@@ -1848,13 +1883,14 @@ rxq_setup(struct rte_eth_dev *dev, struct rxq *rxq, uint16_t desc,
 	struct ibv_qp_attr mod;
 	struct ibv_recv_wr *bad_wr;
 	unsigned int mb_len;
-	int ret = 0;
+	int ret;
 
 	(void)conf; /* Thresholds configuration (ignored). */
 	mb_len = rte_pktmbuf_data_room_size(mp);
 	if (desc == 0) {
+		rte_errno = EINVAL;
 		ERROR("%p: invalid number of RX descriptors", (void *)dev);
-		return EINVAL;
+		goto error;
 	}
 	/* Enable scattered packets support for this queue if necessary. */
 	assert(mb_len >= RTE_PKTMBUF_HEADROOM);
@@ -1876,26 +1912,26 @@ rxq_setup(struct rte_eth_dev *dev, struct rxq *rxq, uint16_t desc,
 	/* Use the entire RX mempool as the memory region. */
 	tmpl.mr = mlx4_mp2mr(priv->pd, mp);
 	if (tmpl.mr == NULL) {
-		ret = EINVAL;
+		rte_errno = EINVAL;
 		ERROR("%p: MR creation failure: %s",
-		      (void *)dev, strerror(ret));
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
 	if (dev->data->dev_conf.intr_conf.rxq) {
 		tmpl.channel = ibv_create_comp_channel(priv->ctx);
 		if (tmpl.channel == NULL) {
-			ret = ENOMEM;
+			rte_errno = ENOMEM;
 			ERROR("%p: Rx interrupt completion channel creation"
 			      " failure: %s",
-			      (void *)dev, strerror(ret));
+			      (void *)dev, strerror(rte_errno));
 			goto error;
 		}
 	}
 	tmpl.cq = ibv_create_cq(priv->ctx, desc, NULL, tmpl.channel, 0);
 	if (tmpl.cq == NULL) {
-		ret = ENOMEM;
+		rte_errno = ENOMEM;
 		ERROR("%p: CQ creation failure: %s",
-		      (void *)dev, strerror(ret));
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
 	DEBUG("priv->device_attr.max_qp_wr is %d",
@@ -1904,9 +1940,8 @@ rxq_setup(struct rte_eth_dev *dev, struct rxq *rxq, uint16_t desc,
 	      priv->device_attr.max_sge);
 	tmpl.qp = rxq_setup_qp(priv, tmpl.cq, desc);
 	if (tmpl.qp == NULL) {
-		ret = (errno ? errno : EINVAL);
 		ERROR("%p: QP creation failure: %s",
-		      (void *)dev, strerror(ret));
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
 	mod = (struct ibv_qp_attr){
@@ -1917,22 +1952,24 @@ rxq_setup(struct rte_eth_dev *dev, struct rxq *rxq, uint16_t desc,
 	};
 	ret = ibv_modify_qp(tmpl.qp, &mod, IBV_QP_STATE | IBV_QP_PORT);
 	if (ret) {
+		rte_errno = ret;
 		ERROR("%p: QP state to IBV_QPS_INIT failed: %s",
-		      (void *)dev, strerror(ret));
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
 	ret = rxq_alloc_elts(&tmpl, desc, NULL);
 	if (ret) {
 		ERROR("%p: RXQ allocation failed: %s",
-		      (void *)dev, strerror(ret));
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
 	ret = ibv_post_recv(tmpl.qp, &(*tmpl.elts)[0].wr, &bad_wr);
 	if (ret) {
+		rte_errno = ret;
 		ERROR("%p: ibv_post_recv() failed for WR %p: %s",
 		      (void *)dev,
 		      (void *)bad_wr,
-		      strerror(ret));
+		      strerror(rte_errno));
 		goto error;
 	}
 	mod = (struct ibv_qp_attr){
@@ -1940,8 +1977,9 @@ rxq_setup(struct rte_eth_dev *dev, struct rxq *rxq, uint16_t desc,
 	};
 	ret = ibv_modify_qp(tmpl.qp, &mod, IBV_QP_STATE);
 	if (ret) {
+		rte_errno = ret;
 		ERROR("%p: QP state to IBV_QPS_RTR failed: %s",
-		      (void *)dev, strerror(ret));
+		      (void *)dev, strerror(rte_errno));
 		goto error;
 	}
 	/* Save port ID. */
@@ -1952,12 +1990,13 @@ rxq_setup(struct rte_eth_dev *dev, struct rxq *rxq, uint16_t desc,
 	rxq_cleanup(rxq);
 	*rxq = tmpl;
 	DEBUG("%p: rxq updated with %p", (void *)rxq, (void *)&tmpl);
-	assert(ret == 0);
 	return 0;
 error:
+	ret = rte_errno;
 	rxq_cleanup(&tmpl);
-	assert(ret > 0);
-	return ret;
+	rte_errno = ret;
+	assert(rte_errno > 0);
+	return -rte_errno;
 }
 
 /**
@@ -1977,7 +2016,7 @@ rxq_setup(struct rte_eth_dev *dev, struct rxq *rxq, uint16_t desc,
  *   Memory pool for buffer allocations.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
@@ -1992,17 +2031,19 @@ mlx4_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 	DEBUG("%p: configuring queue %u for %u descriptors",
 	      (void *)dev, idx, desc);
 	if (idx >= priv->rxqs_n) {
+		rte_errno = EOVERFLOW;
 		ERROR("%p: queue index out of range (%u >= %u)",
 		      (void *)dev, idx, priv->rxqs_n);
 		priv_unlock(priv);
-		return -EOVERFLOW;
+		return -rte_errno;
 	}
 	if (rxq != NULL) {
 		DEBUG("%p: reusing already allocated queue index %u (%p)",
 		      (void *)dev, idx, (void *)rxq);
 		if (priv->started) {
+			rte_errno = EEXIST;
 			priv_unlock(priv);
-			return -EEXIST;
+			return -rte_errno;
 		}
 		(*priv->rxqs)[idx] = NULL;
 		if (idx == 0)
@@ -2011,10 +2052,11 @@ mlx4_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 	} else {
 		rxq = rte_calloc_socket("RXQ", 1, sizeof(*rxq), 0, socket);
 		if (rxq == NULL) {
+			rte_errno = ENOMEM;
 			ERROR("%p: unable to allocate queue index %u",
 			      (void *)dev, idx);
 			priv_unlock(priv);
-			return -ENOMEM;
+			return -rte_errno;
 		}
 	}
 	ret = rxq_setup(dev, rxq, desc, socket, conf, mp);
@@ -2029,7 +2071,7 @@ mlx4_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 		dev->rx_pkt_burst = mlx4_rx_burst;
 	}
 	priv_unlock(priv);
-	return -ret;
+	return ret;
 }
 
 /**
@@ -2081,7 +2123,7 @@ priv_dev_link_interrupt_handler_install(struct priv *, struct rte_eth_dev *);
  *   Pointer to Ethernet device structure.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_dev_start(struct rte_eth_dev *dev)
@@ -2130,7 +2172,7 @@ mlx4_dev_start(struct rte_eth_dev *dev)
 	priv_mac_addr_del(priv);
 	priv->started = 0;
 	priv_unlock(priv);
-	return -ret;
+	return ret;
 }
 
 /**
@@ -2295,7 +2337,7 @@ mlx4_dev_close(struct rte_eth_dev *dev)
  *   Nonzero for link up, otherwise link down.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_set_link(struct priv *priv, int up)
@@ -2325,7 +2367,7 @@ priv_set_link(struct priv *priv, int up)
  *   Pointer to Ethernet device structure.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_set_link_down(struct rte_eth_dev *dev)
@@ -2346,7 +2388,7 @@ mlx4_set_link_down(struct rte_eth_dev *dev)
  *   Pointer to Ethernet device structure.
  *
  * @return
- *   0 on success, errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_set_link_up(struct rte_eth_dev *dev)
@@ -2504,6 +2546,9 @@ mlx4_stats_reset(struct rte_eth_dev *dev)
  *   Pointer to Ethernet device structure.
  * @param wait_to_complete
  *   Wait for request completion (ignored).
+ *
+ * @return
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_link_update(struct rte_eth_dev *dev, int wait_to_complete)
@@ -2518,12 +2563,14 @@ mlx4_link_update(struct rte_eth_dev *dev, int wait_to_complete)
 
 	/* priv_lock() is not taken to allow concurrent calls. */
 
-	if (priv == NULL)
-		return -EINVAL;
+	if (priv == NULL) {
+		rte_errno = EINVAL;
+		return -rte_errno;
+	}
 	(void)wait_to_complete;
 	if (priv_ifreq(priv, SIOCGIFFLAGS, &ifr)) {
-		WARN("ioctl(SIOCGIFFLAGS) failed: %s", strerror(errno));
-		return -1;
+		WARN("ioctl(SIOCGIFFLAGS) failed: %s", strerror(rte_errno));
+		return -rte_errno;
 	}
 	memset(&dev_link, 0, sizeof(dev_link));
 	dev_link.link_status = ((ifr.ifr_flags & IFF_UP) &&
@@ -2531,8 +2578,8 @@ mlx4_link_update(struct rte_eth_dev *dev, int wait_to_complete)
 	ifr.ifr_data = (void *)&edata;
 	if (priv_ifreq(priv, SIOCETHTOOL, &ifr)) {
 		WARN("ioctl(SIOCETHTOOL, ETHTOOL_GSET) failed: %s",
-		     strerror(errno));
-		return -1;
+		     strerror(rte_errno));
+		return -rte_errno;
 	}
 	link_speed = ethtool_cmd_speed(&edata);
 	if (link_speed == -1)
@@ -2556,7 +2603,7 @@ mlx4_link_update(struct rte_eth_dev *dev, int wait_to_complete)
  *   New MTU.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_dev_set_mtu(struct rte_eth_dev *dev, uint16_t mtu)
@@ -2567,9 +2614,9 @@ mlx4_dev_set_mtu(struct rte_eth_dev *dev, uint16_t mtu)
 	priv_lock(priv);
 	/* Set kernel interface MTU first. */
 	if (priv_set_mtu(priv, mtu)) {
-		ret = errno;
+		ret = rte_errno;
 		WARN("cannot set port %u MTU to %u: %s", priv->port, mtu,
-		     strerror(ret));
+		     strerror(rte_errno));
 		goto out;
 	} else
 		DEBUG("adapter port %u MTU set to %u", priv->port, mtu);
@@ -2589,7 +2636,7 @@ mlx4_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, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_dev_get_flow_ctrl(struct rte_eth_dev *dev, struct rte_eth_fc_conf *fc_conf)
@@ -2604,10 +2651,10 @@ mlx4_dev_get_flow_ctrl(struct rte_eth_dev *dev, struct rte_eth_fc_conf *fc_conf)
 	ifr.ifr_data = (void *)&ethpause;
 	priv_lock(priv);
 	if (priv_ifreq(priv, SIOCETHTOOL, &ifr)) {
-		ret = errno;
+		ret = rte_errno;
 		WARN("ioctl(SIOCETHTOOL, ETHTOOL_GPAUSEPARAM)"
 		     " failed: %s",
-		     strerror(ret));
+		     strerror(rte_errno));
 		goto out;
 	}
 
@@ -2637,7 +2684,7 @@ mlx4_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, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_dev_set_flow_ctrl(struct rte_eth_dev *dev, struct rte_eth_fc_conf *fc_conf)
@@ -2665,10 +2712,10 @@ mlx4_dev_set_flow_ctrl(struct rte_eth_dev *dev, struct rte_eth_fc_conf *fc_conf)
 
 	priv_lock(priv);
 	if (priv_ifreq(priv, SIOCETHTOOL, &ifr)) {
-		ret = errno;
+		ret = rte_errno;
 		WARN("ioctl(SIOCETHTOOL, ETHTOOL_SPAUSEPARAM)"
 		     " failed: %s",
-		     strerror(ret));
+		     strerror(rte_errno));
 		goto out;
 	}
 	ret = 0;
@@ -2701,7 +2748,7 @@ const struct rte_flow_ops mlx4_flow_ops = {
  *   Pointer to operation-specific structure.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_dev_filter_ctrl(struct rte_eth_dev *dev,
@@ -2709,12 +2756,10 @@ mlx4_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;
+			break;
 		*(const void **)arg = &mlx4_flow_ops;
 		return 0;
 	default:
@@ -2722,7 +2767,8 @@ mlx4_dev_filter_ctrl(struct rte_eth_dev *dev,
 		      (void *)dev, filter_type);
 		break;
 	}
-	return -ret;
+	rte_errno = ENOTSUP;
+	return -rte_errno;
 }
 
 static const struct eth_dev_ops mlx4_dev_ops = {
@@ -2757,7 +2803,7 @@ static const struct eth_dev_ops mlx4_dev_ops = {
  *   PCI bus address output buffer.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_ibv_device_to_pci_addr(const struct ibv_device *device,
@@ -2768,8 +2814,10 @@ mlx4_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;
@@ -2807,15 +2855,16 @@ mlx4_ibv_device_to_pci_addr(const struct ibv_device *device,
  *   MAC address output buffer.
  *
  * @return
- *   0 on success, -1 on failure and errno is set.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_get_mac(struct priv *priv, uint8_t (*mac)[ETHER_ADDR_LEN])
 {
 	struct ifreq request;
+	int ret = priv_ifreq(priv, SIOCGIFHWADDR, &request);
 
-	if (priv_ifreq(priv, SIOCGIFHWADDR, &request))
-		return -1;
+	if (ret)
+		return ret;
 	memcpy(mac, request.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
 	return 0;
 }
@@ -2953,7 +3002,7 @@ mlx4_dev_interrupt_handler(void *cb_arg)
  * @param dev
  *   Pointer to the rte_eth_dev structure.
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_dev_interrupt_handler_uninstall(struct priv *priv, struct rte_eth_dev *dev)
@@ -2967,11 +3016,9 @@ priv_dev_interrupt_handler_uninstall(struct priv *priv, struct rte_eth_dev *dev)
 					   mlx4_dev_interrupt_handler,
 					   dev);
 	if (ret < 0) {
-		ERROR("rte_intr_callback_unregister failed with %d"
-		      "%s%s%s", ret,
-		      (errno ? " (errno: " : ""),
-		      (errno ? strerror(errno) : ""),
-		      (errno ? ")" : ""));
+		rte_errno = ret;
+		ERROR("rte_intr_callback_unregister failed with %d %s",
+		      ret, strerror(rte_errno));
 	}
 	priv->intr_handle.fd = 0;
 	priv->intr_handle.type = RTE_INTR_HANDLE_UNKNOWN;
@@ -2986,7 +3033,7 @@ priv_dev_interrupt_handler_uninstall(struct priv *priv, struct rte_eth_dev *dev)
  * @param dev
  *   Pointer to the rte_eth_dev structure.
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_dev_interrupt_handler_install(struct priv *priv,
@@ -3006,10 +3053,11 @@ priv_dev_interrupt_handler_install(struct priv *priv,
 	flags = fcntl(priv->ctx->async_fd, F_GETFL);
 	rc = fcntl(priv->ctx->async_fd, F_SETFL, flags | O_NONBLOCK);
 	if (rc < 0) {
+		rte_errno = errno ? errno : EINVAL;
 		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;
-		return -errno;
+		return -rte_errno;
 	} else {
 		priv->intr_handle.fd = priv->ctx->async_fd;
 		priv->intr_handle.type = RTE_INTR_HANDLE_EXT;
@@ -3017,9 +3065,10 @@ priv_dev_interrupt_handler_install(struct priv *priv,
 						 mlx4_dev_interrupt_handler,
 						 dev);
 		if (rc) {
+			rte_errno = -rc;
 			ERROR("rte_intr_callback_register failed "
-			      " (errno: %s)", strerror(errno));
-			return rc;
+			      " (rte_errno: %s)", strerror(rte_errno));
+			return -rte_errno;
 		}
 	}
 	return 0;
@@ -3033,7 +3082,7 @@ priv_dev_interrupt_handler_install(struct priv *priv,
  * @param dev
  *   Pointer to the rte_eth_dev structure.
  * @return
- *   0 on success, negative value on error.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_dev_removal_interrupt_handler_uninstall(struct priv *priv,
@@ -3054,7 +3103,7 @@ priv_dev_removal_interrupt_handler_uninstall(struct priv *priv,
  * @param dev
  *   Pointer to the rte_eth_dev structure.
  * @return
- *   0 on success, negative value on error,
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_dev_link_interrupt_handler_uninstall(struct priv *priv,
@@ -3072,7 +3121,7 @@ priv_dev_link_interrupt_handler_uninstall(struct priv *priv,
 		if (rte_eal_alarm_cancel(mlx4_dev_link_status_handler,
 					 dev)) {
 			ERROR("rte_eal_alarm_cancel failed "
-			      " (errno: %s)", strerror(rte_errno));
+			      " (rte_errno: %s)", strerror(rte_errno));
 			return -rte_errno;
 		}
 	priv->pending_alarm = 0;
@@ -3087,7 +3136,7 @@ priv_dev_link_interrupt_handler_uninstall(struct priv *priv,
  * @param dev
  *   Pointer to the rte_eth_dev structure.
  * @return
- *   0 on success, negative value on error.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_dev_link_interrupt_handler_install(struct priv *priv,
@@ -3112,7 +3161,7 @@ priv_dev_link_interrupt_handler_install(struct priv *priv,
  * @param dev
  *   Pointer to the rte_eth_dev structure.
  * @return
- *   0 on success, negative value on error.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_dev_removal_interrupt_handler_install(struct priv *priv,
@@ -3136,7 +3185,7 @@ priv_dev_removal_interrupt_handler_install(struct priv *priv,
  *   Pointer to private structure.
  *
  * @return
- *   0 on success, negative on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 priv_rx_intr_vec_enable(struct priv *priv)
@@ -3152,9 +3201,10 @@ priv_rx_intr_vec_enable(struct priv *priv)
 	priv_rx_intr_vec_disable(priv);
 	intr_handle->intr_vec = malloc(sizeof(intr_handle->intr_vec[rxqs_n]));
 	if (intr_handle->intr_vec == NULL) {
+		rte_errno = ENOMEM;
 		ERROR("failed to allocate memory for interrupt vector,"
 		      " Rx interrupts will not be supported");
-		return -ENOMEM;
+		return -rte_errno;
 	}
 	intr_handle->type = RTE_INTR_HANDLE_EXT;
 	for (i = 0; i != n; ++i) {
@@ -3172,20 +3222,22 @@ priv_rx_intr_vec_enable(struct priv *priv)
 			continue;
 		}
 		if (count >= RTE_MAX_RXTX_INTR_VEC_ID) {
+			rte_errno = E2BIG;
 			ERROR("too many Rx queues for interrupt vector size"
 			      " (%d), Rx interrupts cannot be enabled",
 			      RTE_MAX_RXTX_INTR_VEC_ID);
 			priv_rx_intr_vec_disable(priv);
-			return -1;
+			return -rte_errno;
 		}
 		fd = rxq->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);
 			priv_rx_intr_vec_disable(priv);
-			return rc;
+			return -rte_errno;
 		}
 		intr_handle->intr_vec[i] = RTE_INTR_VEC_RXTX_OFFSET + count;
 		intr_handle->efds[count] = fd;
@@ -3224,7 +3276,7 @@ priv_rx_intr_vec_disable(struct priv *priv)
  *   Rx queue index.
  *
  * @return
- *   0 on success, negative on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_rx_intr_enable(struct rte_eth_dev *dev, uint16_t idx)
@@ -3237,8 +3289,10 @@ mlx4_rx_intr_enable(struct rte_eth_dev *dev, uint16_t idx)
 		ret = EINVAL;
 	else
 		ret = ibv_req_notify_cq(rxq->cq, 0);
-	if (ret)
+	if (ret) {
+		rte_errno = ret;
 		WARN("unable to arm interrupt on rx queue %d", idx);
+	}
 	return -ret;
 }
 
@@ -3251,7 +3305,7 @@ mlx4_rx_intr_enable(struct rte_eth_dev *dev, uint16_t idx)
  *   Rx queue index.
  *
  * @return
- *   0 on success, negative on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_rx_intr_disable(struct rte_eth_dev *dev, uint16_t idx)
@@ -3269,11 +3323,13 @@ mlx4_rx_intr_disable(struct rte_eth_dev *dev, uint16_t idx)
 		if (ret || ev_cq != rxq->cq)
 			ret = EINVAL;
 	}
-	if (ret)
+	if (ret) {
+		rte_errno = ret;
 		WARN("unable to disable interrupt on rx queue %d",
 		     idx);
-	else
+	} else {
 		ibv_ack_cq_events(rxq->cq, 1);
+	}
 	return -ret;
 }
 
@@ -3288,7 +3344,7 @@ mlx4_rx_intr_disable(struct rte_eth_dev *dev, uint16_t idx)
  *   Shared configuration data.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_arg_parse(const char *key, const char *val, struct mlx4_conf *conf)
@@ -3298,18 +3354,21 @@ mlx4_arg_parse(const char *key, const char *val, struct mlx4_conf *conf)
 	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(MLX4_PMD_PORT_KVARG, key) == 0) {
 		if (!(conf->ports.present & (1 << tmp))) {
+			rte_errno = EINVAL;
 			ERROR("invalid port index %lu", tmp);
-			return -EINVAL;
+			return -rte_errno;
 		}
 		conf->ports.enabled |= 1 << tmp;
 	} else {
+		rte_errno = EINVAL;
 		WARN("%s: unknown parameter", key);
-		return -EINVAL;
+		return -rte_errno;
 	}
 	return 0;
 }
@@ -3321,7 +3380,7 @@ mlx4_arg_parse(const char *key, const char *val, struct mlx4_conf *conf)
  *   Device arguments structure.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_args(struct rte_devargs *devargs, struct mlx4_conf *conf)
@@ -3335,8 +3394,9 @@ mlx4_args(struct rte_devargs *devargs, struct mlx4_conf *conf)
 		return 0;
 	kvlist = rte_kvargs_parse(devargs->args, pmd_mlx4_init_params);
 	if (kvlist == NULL) {
+		rte_errno = EINVAL;
 		ERROR("failed to parse kvargs");
-		return -EINVAL;
+		return -rte_errno;
 	}
 	/* Process parameters. */
 	for (i = 0; pmd_mlx4_init_params[i]; ++i) {
@@ -3372,7 +3432,7 @@ static struct rte_pci_driver mlx4_driver;
  *   PCI device information.
  *
  * @return
- *   0 on success, negative errno value on failure.
+ *   0 on success, negative errno value otherwise and rte_errno is set.
  */
 static int
 mlx4_pci_probe(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
@@ -3393,10 +3453,11 @@ mlx4_pci_probe(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
 
 	list = ibv_get_device_list(&i);
 	if (list == NULL) {
-		assert(errno);
-		if (errno == ENOSYS)
+		rte_errno = errno;
+		assert(rte_errno);
+		if (rte_errno == ENOSYS)
 			ERROR("cannot list devices, is ib_uverbs loaded?");
-		return -errno;
+		return -rte_errno;
 	}
 	assert(i >= 0);
 	/*
@@ -3427,20 +3488,23 @@ mlx4_pci_probe(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
 		ibv_free_device_list(list);
 		switch (err) {
 		case 0:
+			rte_errno = ENODEV;
 			ERROR("cannot access device, is mlx4_ib loaded?");
-			return -ENODEV;
+			return -rte_errno;
 		case EINVAL:
+			rte_errno = EINVAL;
 			ERROR("cannot use device, are drivers up to date?");
-			return -EINVAL;
+			return -rte_errno;
 		}
 		assert(err > 0);
-		return -err;
+		rte_errno = err;
+		return -rte_errno;
 	}
 	ibv_dev = list[i];
 
 	DEBUG("device opened");
 	if (ibv_query_device(attr_ctx, &device_attr)) {
-		err = ENODEV;
+		rte_errno = ENODEV;
 		goto error;
 	}
 	INFO("%u port(s) detected", device_attr.phys_port_cnt);
@@ -3449,7 +3513,7 @@ mlx4_pci_probe(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
 		conf.ports.present |= 1 << i;
 	if (mlx4_args(pci_dev->device.devargs, &conf)) {
 		ERROR("failed to process device arguments");
-		err = EINVAL;
+		rte_errno = EINVAL;
 		goto error;
 	}
 	/* Use all ports when none are defined */
@@ -3472,22 +3536,22 @@ mlx4_pci_probe(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
 
 		ctx = ibv_open_device(ibv_dev);
 		if (ctx == NULL) {
-			err = ENODEV;
+			rte_errno = ENODEV;
 			goto port_error;
 		}
 
 		/* Check port status. */
 		err = ibv_query_port(ctx, port, &port_attr);
 		if (err) {
-			ERROR("port query failed: %s", strerror(err));
-			err = ENODEV;
+			rte_errno = err;
+			ERROR("port query failed: %s", strerror(rte_errno));
 			goto port_error;
 		}
 
 		if (port_attr.link_layer != IBV_LINK_LAYER_ETHERNET) {
+			rte_errno = ENOTSUP;
 			ERROR("port %d is not configured in Ethernet mode",
 			      port);
-			err = EINVAL;
 			goto port_error;
 		}
 
@@ -3499,8 +3563,8 @@ mlx4_pci_probe(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
 		/* Allocate protection domain. */
 		pd = ibv_alloc_pd(ctx);
 		if (pd == NULL) {
+			rte_errno = ENOMEM;
 			ERROR("PD allocation failure");
-			err = ENOMEM;
 			goto port_error;
 		}
 
@@ -3509,8 +3573,8 @@ mlx4_pci_probe(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
 				   sizeof(*priv),
 				   RTE_CACHE_LINE_SIZE);
 		if (priv == NULL) {
+			rte_errno = ENOMEM;
 			ERROR("priv allocation failure");
-			err = ENOMEM;
 			goto port_error;
 		}
 
@@ -3524,8 +3588,7 @@ mlx4_pci_probe(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
 		/* Configure the first MAC address by default. */
 		if (priv_get_mac(priv, &mac.addr_bytes)) {
 			ERROR("cannot get MAC address, is mlx4_en loaded?"
-			      " (errno: %s)", strerror(errno));
-			err = ENODEV;
+			      " (rte_errno: %s)", strerror(rte_errno));
 			goto port_error;
 		}
 		INFO("port %u MAC address is %02x:%02x:%02x:%02x:%02x:%02x",
@@ -3562,7 +3625,7 @@ mlx4_pci_probe(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
 		}
 		if (eth_dev == NULL) {
 			ERROR("can not allocate rte ethdev");
-			err = ENOMEM;
+			rte_errno = ENOMEM;
 			goto port_error;
 		}
 
@@ -3620,8 +3683,8 @@ mlx4_pci_probe(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
 		claim_zero(ibv_close_device(attr_ctx));
 	if (list)
 		ibv_free_device_list(list);
-	assert(err >= 0);
-	return -err;
+	assert(rte_errno >= 0);
+	return -rte_errno;
 }
 
 static const struct rte_pci_id mlx4_pci_id_map[] = {
-- 
2.1.4