[PATCH net-next] net: dsa: loop: Fix devlink resource ID

[PATCH net-next] net: dsa: loop: Fix devlink resource ID

[David Yang]

Fix collision with DEVLINK_RESOURCE_ID_PARENT_TOP (0) by keeping the
real resource IDs in enum dsa_loop_devlink_resource_id starting at 1.

Signed-off-by: David Yang <mmyangfl@gmail.com>
---
 drivers/net/dsa/dsa_loop.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/dsa/dsa_loop.c b/drivers/net/dsa/dsa_loop.c
index 7058faf23592..9497c84fb249 100644
--- a/drivers/net/dsa/dsa_loop.c
+++ b/drivers/net/dsa/dsa_loop.c
@@ -75,6 +75,7 @@ static struct phy_device *phydevs[PHY_MAX_ADDR];
 static struct mdio_device *switch_mdiodev;
 
 enum dsa_loop_devlink_resource_id {
+	DSA_LOOP_DEVLINK_PARAM_NONE,  /* DEVLINK_RESOURCE_ID_PARENT_TOP */
 	DSA_LOOP_DEVLINK_PARAM_ID_VTU,
 };
 
-- 
2.53.0

Re: [PATCH net-next] net: dsa: loop: Fix devlink resource ID

[Andrew Lunn]

On Wed, Jun 10, 2026 at 02:25:45PM +0800, David Yang wrote:
> Fix collision with DEVLINK_RESOURCE_ID_PARENT_TOP (0) by keeping the
> real resource IDs in enum dsa_loop_devlink_resource_id starting at 1.

Please could you expand on this. What is actually wrong here?

When i look at mv88e6xxx, hellcreak and b53 it does the same.

     Andrew

Re: [PATCH net-next] net: dsa: loop: Fix devlink resource ID

[David Yang]

On Wed, Jun 10, 2026 at 3:23 PM Andrew Lunn <andrew@lunn.ch> wrote:
>
> On Wed, Jun 10, 2026 at 02:25:45PM +0800, David Yang wrote:
> > Fix collision with DEVLINK_RESOURCE_ID_PARENT_TOP (0) by keeping the
> > real resource IDs in enum dsa_loop_devlink_resource_id starting at 1.
>
> Please could you expand on this. What is actually wrong here?
>
> When i look at mv88e6xxx, hellcreak and b53 it does the same.
>
>      Andrew

dsa_devlink_resource_register() is, but other users of
devl_resource_register() (mlxsw and netdevsim) avoid 0 explicitly.

In this case for dsa_loop, the usage is semantically questionable (0
being its own parent) but might just work as well. But it is a real
problem on mv88e6xxx, where ATU_bin_* are in fact registered as
top-level siblings, not as children of ATU, due to ATU ID colliding
with PARENT_TOP.

Re: [PATCH net-next] net: dsa: loop: Fix devlink resource ID

[Andrew Lunn]

On Wed, Jun 10, 2026 at 09:36:59PM +0800, David Yang wrote:
> On Wed, Jun 10, 2026 at 3:23 PM Andrew Lunn <andrew@lunn.ch> wrote:
> >
> > On Wed, Jun 10, 2026 at 02:25:45PM +0800, David Yang wrote:
> > > Fix collision with DEVLINK_RESOURCE_ID_PARENT_TOP (0) by keeping the
> > > real resource IDs in enum dsa_loop_devlink_resource_id starting at 1.
> >
> > Please could you expand on this. What is actually wrong here?
> >
> > When i look at mv88e6xxx, hellcreak and b53 it does the same.
> >
> >      Andrew
> 
> dsa_devlink_resource_register() is, but other users of
> devl_resource_register() (mlxsw and netdevsim) avoid 0 explicitly.
> 
> In this case for dsa_loop, the usage is semantically questionable (0
> being its own parent) but might just work as well. But it is a real
> problem on mv88e6xxx, where ATU_bin_* are in fact registered as
> top-level siblings, not as children of ATU, due to ATU ID colliding
> with PARENT_TOP.

So please produce a patchset fixing all users of
devl_resource_register() which pass 0. And then maybe add WARN_ON()?

    Andrew

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