netdev - Re: [PATCH v2] ravb: Fixed the problem that rmmod can not be done

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Message-ID: <0e7d72fe-ea70-612c-7a50-ad1ff905ddf4@gmail.com>
Date:   Fri, 31 Jul 2020 21:32:32 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...il.com>
To:     Yuusuke Ashizuka <ashiduka@...itsu.com>
Cc:     netdev@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH v2] ravb: Fixed the problem that rmmod can not be done

On 7/30/20 1:01 PM, Yuusuke Ashizuka wrote:

   CCing DaveM (as you should have done from the start)...

> ravb is a module driver, but I cannot rmmod it after insmod it.
> ravb does mdio_init() at the time of probe, and module->refcnt is incremented
> by alloc_mdio_bitbang() called after that.
> Therefore, even if ifup is not performed, the driver is in use and rmmod cannot
> be performed.
> 
> $ lsmod
> Module                  Size  Used by

   Did you also build mdio-bitbang.c as a module? For the in-kernal driver, not
being able to rmmod the 'ravb' one sounds logical. :-)

> ravb                   40960  1
> $ rmmod ravb
> rmmod: ERROR: Module ravb is in use
> 
> Fixed to execute mdio_init() at open and free_mdio() at close, thereby rmmod is

    Call ravb_mdio_init() at open and free_mdio_bitbang() at close.

> possible in the ifdown state.

Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")

> Signed-off-by: Yuusuke Ashizuka <ashiduka@...itsu.com>

Reviewed-by: Sergei Shtylyov <sergei.shtylyov@...il.com>

[...]
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index 99f7aae102ce..df89d09b253e 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -1342,6 +1342,51 @@ static inline int ravb_hook_irq(unsigned int irq, irq_handler_t handler,
>  	return error;
>  }
>  
> +/* MDIO bus init function */
> +static int ravb_mdio_init(struct ravb_private *priv)
> +{
> +	struct platform_device *pdev = priv->pdev;
> +	struct device *dev = &pdev->dev;
> +	int error;
> +
> +	/* Bitbang init */
> +	priv->mdiobb.ops = &bb_ops;
> +
> +	/* MII controller setting */
> +	priv->mii_bus = alloc_mdio_bitbang(&priv->mdiobb);
> +	if (!priv->mii_bus)
> +		return -ENOMEM;
> +
> +	/* Hook up MII support for ethtool */
> +	priv->mii_bus->name = "ravb_mii";
> +	priv->mii_bus->parent = dev;
> +	snprintf(priv->mii_bus->id, MII_BUS_ID_SIZE, "%s-%x",
> +		 pdev->name, pdev->id);
> +
> +	/* Register MDIO bus */
> +	error = of_mdiobus_register(priv->mii_bus, dev->of_node);
> +	if (error)
> +		goto out_free_bus;
> +
> +	return 0;
> +
> +out_free_bus:
> +	free_mdio_bitbang(priv->mii_bus);
> +	return error;
> +}
> +
> +/* MDIO bus release function */
> +static int ravb_mdio_release(struct ravb_private *priv)
> +{
> +	/* Unregister mdio bus */
> +	mdiobus_unregister(priv->mii_bus);
> +
> +	/* Free bitbang info */
> +	free_mdio_bitbang(priv->mii_bus);
> +
> +	return 0;
> +}
> +
[...]
> @@ -1887,51 +1942,6 @@ static const struct net_device_ops ravb_netdev_ops = {
>  	.ndo_set_features	= ravb_set_features,
>  };
>  
> -/* MDIO bus init function */
> -static int ravb_mdio_init(struct ravb_private *priv)
> -{
> -	struct platform_device *pdev = priv->pdev;
> -	struct device *dev = &pdev->dev;
> -	int error;
> -
> -	/* Bitbang init */
> -	priv->mdiobb.ops = &bb_ops;
> -
> -	/* MII controller setting */
> -	priv->mii_bus = alloc_mdio_bitbang(&priv->mdiobb);
> -	if (!priv->mii_bus)
> -		return -ENOMEM;
> -
> -	/* Hook up MII support for ethtool */
> -	priv->mii_bus->name = "ravb_mii";
> -	priv->mii_bus->parent = dev;
> -	snprintf(priv->mii_bus->id, MII_BUS_ID_SIZE, "%s-%x",
> -		 pdev->name, pdev->id);
> -
> -	/* Register MDIO bus */
> -	error = of_mdiobus_register(priv->mii_bus, dev->of_node);
> -	if (error)
> -		goto out_free_bus;
> -
> -	return 0;
> -
> -out_free_bus:
> -	free_mdio_bitbang(priv->mii_bus);
> -	return error;
> -}
> -
> -/* MDIO bus release function */
> -static int ravb_mdio_release(struct ravb_private *priv)
> -{
> -	/* Unregister mdio bus */
> -	mdiobus_unregister(priv->mii_bus);
> -
> -	/* Free bitbang info */
> -	free_mdio_bitbang(priv->mii_bus);
> -
> -	return 0;
> -}
> -

   Dave, would you tolerate the forward declarations here instead (to avoid the function moves, to be later
done in the net-next tree)?

[...]

MBR, Sergei