When a user port has a label in device tree, the corresponding
netdevice is, to quote include/uapi/linux/netdevice.h, "predictably
named by the kernel". This is also explicitly one of the intended use
cases for NET_NAME_PREDICTABLE, quoting 685343fc3ba6 ("net: add
name_assign_type netdev attribute"):

  NET_NAME_PREDICTABLE:
    The ifname has been assigned by the kernel in a predictable way
    [...] Examples include [...] and names deduced from hardware
    properties (including being given explicitly by the firmware).

Expose that information properly for the benefit of userspace tools
that make decisions based on the name_assign_type attribute,
e.g. a systemd-udev rule with "kernel" in NamePolicy.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 net/dsa/slave.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index d19e9a536b8f..dfefcc4a9ccf 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -2385,7 +2385,7 @@ int dsa_slave_create(struct dsa_port *port)
 
 	if (port->name) {
 		name = port->name;
-		assign_type = NET_NAME_UNKNOWN;
+		assign_type = NET_NAME_PREDICTABLE;
 	} else {
 		name = "eth%d";
 		assign_type = NET_NAME_UNKNOWN;
-- 
2.37.2

On 11/16/2022 2:52 AM, Rasmus Villemoes wrote:
> When a user port has a label in device tree, the corresponding
> netdevice is, to quote include/uapi/linux/netdevice.h, "predictably
> named by the kernel". This is also explicitly one of the intended use
> cases for NET_NAME_PREDICTABLE, quoting 685343fc3ba6 ("net: add
> name_assign_type netdev attribute"):
> 
>    NET_NAME_PREDICTABLE:
>      The ifname has been assigned by the kernel in a predictable way
>      [...] Examples include [...] and names deduced from hardware
>      properties (including being given explicitly by the firmware).
> 
> Expose that information properly for the benefit of userspace tools
> that make decisions based on the name_assign_type attribute,
> e.g. a systemd-udev rule with "kernel" in NamePolicy.
> 
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>

Reviewed-by: Florian Fainelli <f.faineli@gmail.com>
-- 
Florian

On Wed, Nov 16, 2022 at 11:52:03AM +0100, Rasmus Villemoes wrote:
> When a user port has a label in device tree, the corresponding
> netdevice is, to quote include/uapi/linux/netdevice.h, "predictably
> named by the kernel". This is also explicitly one of the intended use
> cases for NET_NAME_PREDICTABLE, quoting 685343fc3ba6 ("net: add
> name_assign_type netdev attribute"):
> 
>   NET_NAME_PREDICTABLE:
>     The ifname has been assigned by the kernel in a predictable way
>     [...] Examples include [...] and names deduced from hardware
>     properties (including being given explicitly by the firmware).
> 
> Expose that information properly for the benefit of userspace tools
> that make decisions based on the name_assign_type attribute,
> e.g. a systemd-udev rule with "kernel" in NamePolicy.
> 
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew