linux-kernel - Re: [PATCH net-next] net: mdio: get/put device node during (un)registration

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Date: Wed, 3 Jan 2024 18:50:06 -0300
From: Luiz Angelo Daros de Luca <luizluca@...il.com>
To: "Russell King (Oracle)" <linux@...linux.org.uk>
Cc: kuba@...nel.org, netdev@...r.kernel.org, andrew@...n.ch, 
	hkallweit1@...il.com, davem@...emloft.net, edumazet@...gle.com, 
	pabeni@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] net: mdio: get/put device node during (un)registration

> Please test to check that this addresses your issue. Thanks.
>
> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
> index 6cf73c15635b..afbad1ad8683 100644
> --- a/drivers/net/phy/mdio_bus.c
> +++ b/drivers/net/phy/mdio_bus.c
> @@ -193,6 +193,10 @@ static void mdiobus_release(struct device *d)
>              bus->state != MDIOBUS_ALLOCATED,
>              "%s: not in RELEASED or ALLOCATED state\n",
>              bus->id);
> +
> +       if (bus->state == MDIOBUS_RELEASED)
> +               fwnode_handle_put(dev_fwnode(d));
> +
>         kfree(bus);
>  }
>
> @@ -684,6 +688,15 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
>         bus->dev.groups = NULL;
>         dev_set_name(&bus->dev, "%s", bus->id);
>
> +       /* If the bus state is allocated, we're registering a fresh bus
> +        * that may have a fwnode associated with it. Grab a reference
> +        * to the fwnode. This will be dropped when the bus is released.
> +        * If the bus was set to unregistered, it means that the bus was
> +        * previously registered, and we've already grabbed a reference.
> +        */
> +       if (bus->state == MDIOBUS_ALLOCATED)
> +               fwnode_handle_get(dev_fwnode(&bus->dev));
> +
>         /* We need to set state to MDIOBUS_UNREGISTERED to correctly release
>          * the device in mdiobus_free()
>          *
> --

Thanks Russel. It is much better than my approach. You simply get/put
during registration/unregistration when a node is defined, no matter
who defined it (of_mdiobus_register or anything else). Clean and
simple.

Regards,

Luiz