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net/mlx5: fix interface name parameter definition

PATCH In review Gregory Etelson 3 participants 4 messages Aug 10, 2025 – Sep 2, 2025 Network drivers

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Gregory Etelson

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#0 lore raw

PATCH 1/1 net/mlx5: fix interface name parameter definition

The patch fixes ifname parameter as a character buffer.

Fixes 1256805dd54d ("net/mlx5: move Linux-specific functions")
Signed-off-by Gregory Etelson <[email protected]>
Acked-by Dariusz Sosnowski <[email protected]>
---
 drivers/net/mlx5/linux/mlx5_ethdev_os.c   | 11 +++++------
 drivers/net/mlx5/linux/mlx5_os.c          |  2 +-
 drivers/net/mlx5/mlx5.h                   |  3 +--
 drivers/net/mlx5/windows/mlx5_ethdev_os.c |  4 ++--
 4 files changed, 9 insertions(+), 11 deletions(-)
drivers/net/mlx5/linux/mlx5_ethdev_os.c +5 -6
index 9daeda5435..eeb95bead0 100644
@@ -73,7 +73,7 @@ mlx5_auxiliary_get_ifindex(const char *sf_name)
  *   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)[MLX5_NAMESIZE])
+mlx5_get_ifname(const struct rte_eth_dev *dev, char ifname[MLX5_NAMESIZE])
 {
 	struct mlx5_priv *priv = dev->data->dev_private;
 	unsigned int ifindex;

@@ -87,12 +87,11 @@ mlx5_get_ifname(const struct rte_eth_dev *dev, char (*ifname)[MLX5_NAMESIZE])
 	ifindex = mlx5_ifindex(dev);
 	if (!ifindex) {
 		if (!priv->representor)
-			return mlx5_get_ifname_sysfs(priv->sh->ibdev_path,
-						     *ifname);
+			return mlx5_get_ifname_sysfs(priv->sh->ibdev_path, ifname);
 		rte_errno = ENXIO;
 		return -rte_errno;
 	}
-	if (if_indextoname(ifindex, &(*ifname)[0]))
+	if (if_indextoname(ifindex, ifname))
 		return 0;
 	rte_errno = errno;
 	return -rte_errno;

@@ -150,10 +149,10 @@ mlx5_ifreq_by_ifname(const char *ifname, int req, struct ifreq *ifr)
 static int
 mlx5_ifreq(const struct rte_eth_dev *dev, int req, struct ifreq *ifr)
 {
-	char ifname[sizeof(ifr->ifr_name)];
+	char ifname[MLX5_NAMESIZE];
 	int ret;
 
-	ret = mlx5_get_ifname(dev, &ifname);
+	ret = mlx5_get_ifname(dev, ifname);
 	if (ret)
 		return -rte_errno;
 	return mlx5_ifreq_by_ifname(ifname, req, ifr);
drivers/net/mlx5/linux/mlx5_os.c +1 -1
index 696a3e12c7..03c5191095 100644
@@ -1578,7 +1578,7 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
 	{
 		char ifname[MLX5_NAMESIZE];
 
-		if (mlx5_get_ifname(eth_dev, &ifname) == 0)
+		if (mlx5_get_ifname(eth_dev, ifname) == 0)
 			DRV_LOG(DEBUG, "port %u ifname is \"%s\"",
 				eth_dev->data->port_id, ifname);
 		else
drivers/net/mlx5/mlx5.h +1 -2
index c08894cd03..3e293216bb 100644
@@ -2336,8 +2336,7 @@ uint64_t mlx5_get_restore_flags(struct rte_eth_dev *dev,
 
 /* mlx5_ethdev_os.c */
 
-int mlx5_get_ifname(const struct rte_eth_dev *dev,
-			char (*ifname)[MLX5_NAMESIZE]);
+int mlx5_get_ifname(const struct rte_eth_dev *dev, char ifname[MLX5_NAMESIZE]);
 unsigned int mlx5_ifindex(const struct rte_eth_dev *dev);
 int mlx5_get_mac(struct rte_eth_dev *dev, uint8_t (*mac)[RTE_ETHER_ADDR_LEN]);
 int mlx5_get_mtu(struct rte_eth_dev *dev, uint16_t *mtu);
drivers/net/mlx5/windows/mlx5_ethdev_os.c +2 -2
index 49f750be68..2e9c9d5b3f 100644
@@ -56,7 +56,7 @@ mlx5_get_mac(struct rte_eth_dev *dev, uint8_t (*mac)[RTE_ETHER_ADDR_LEN])
  *   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)[MLX5_NAMESIZE])
+mlx5_get_ifname(const struct rte_eth_dev *dev, char ifname[MLX5_NAMESIZE])
 {
 	struct mlx5_priv *priv;
 	mlx5_context_st *context_obj;

@@ -67,7 +67,7 @@ mlx5_get_ifname(const struct rte_eth_dev *dev, char (*ifname)[MLX5_NAMESIZE])
 	}
 	priv = dev->data->dev_private;
 	context_obj = (mlx5_context_st *)priv->sh->cdev->ctx;
-	strncpy(*ifname, context_obj->mlx5_dev.name, MLX5_NAMESIZE);
+	strncpy(ifname, context_obj->mlx5_dev.name, MLX5_NAMESIZE);
 	return 0;
 }
Signature · 1 line
2.48.1
#1 lore raw
Quoted 7 lines · On Sun, 10 Aug 2025 16:22:59 +0300 Gregory Etelson <[email protected]> wrote:

The patch fixes ifname parameter as a character buffer.

Fixes 1256805dd54d ("net/mlx5: move Linux-specific functions")
Signed-off-by Gregory Etelson <[email protected]>
Acked-by Dariusz Sosnowski <[email protected]>

---

This looks better but did you know that the ifname can never be as big as MLX5_NAMESIZE. Kernel limits to IFNAMSIZ (ie 16). The largest allowable interface name in Linux is 15 characters.

Looks like:

	MLX5_NAMESIZE := MXL5_FS_NAME_MAX := IBV_SYSFS_NAME_MAX + 1 = 64 + 1 = 65

Because Linux interface name length is fixed by BSD legacy ABI's it will never be longer.

author
#2 lore raw

Hello Stephen,

Quoted 8 lines
Quoted 7 lines

The patch fixes ifname parameter as a character buffer.

Fixes 1256805dd54d ("net/mlx5: move Linux-specific functions")
Signed-off-by Gregory Etelson <[email protected]>
Acked-by Dariusz Sosnowski <[email protected]>

---

Quoted 8 lines

This looks better but did you know that the ifname can never be as big as MLX5_NAMESIZE. Kernel limits to IFNAMSIZ (ie 16). The largest allowable interface name in Linux is 15 characters.

Looks like:

       MLX5_NAMESIZE := MXL5_FS_NAME_MAX := IBV_SYSFS_NAME_MAX + 1 = 64 + 1 = 65

Because Linux interface name length is fixed by BSD legacy ABI's it will never be longer.

The MLX5 PMD defines MLX5_NAMESIZE macro for Linux and Windows.

The Linux definition is in the drivers/net/mlx5/linux/mlx5_os.h:
#define MLX5_NAMESIZE IF_NAMESIZE

Linux API sets IF_NAMESIZE to 16.

The Windows definition is in the drivers/net/mlx5/windows/mlx5_os.h:
#define MLX5_NAMESIZE MLX5_FS_NAME_MAX.

The MLX5_FS_NAME_MAX macro also has different definitions for Linux and Windows:

drivers/common/mlx5/linux/mlx5_common_os.h
MLX5_FS_NAME_MAX = IBV_SYSFS_NAME_MAX + 1

IB verbs API sets IBV_SYSFS_NAME_MAX to 265.

drivers/common/mlx5/windows/mlx5_common_os.h: MLX5_FS_NAME_MAX = MLX5_DEVX_DEVICE_NAME_SIZE + 1

MLX5_DEVX_DEVICE_NAME_SIZE is defined by NVIDIA/Mellanox’s DevX (WinOF2) user-space headers for Windows and is set to 64.

Regards,
Gregory