Re: [PATCH net] net: usb: lan78xx: reject invalid EEPROM write requests

[Andrew Lunn <andrew@lunn.ch>]

On Fri, Oct 09, 2026 at 02:57:02AM +0200, Stefano Munari wrote:
> The runtime PM handling removed the -EINVAL return for invalid
> EEPROM/OTP write requests. These requests now return zero from a
> successful usb_autopm_get_interface() call, even though no data is
> written.
> 
> Set ret to -EINVAL for invalid requests while preserving the runtime
> PM reference release.
> 
> Fixes: 8a7ffeb795f8 ("lan78xx: Fix for eeprom read/write when device auto suspend")
> Signed-off-by: Stefano Munari <stefanomunari.sm@gmail.com>
> ---
> Tested on a Raspberry Pi 3 Model B+ with the onboard Ethernet
> controller, using raspberrypi/linux commit bba53a117a4a on the
> rpi-6.6.y branch as the baseline.
> 
>   ethtool -E eth0 magic 0 offset 0 length 1 value 0
> 
> The command succeeds without the patch and reports "Invalid argument"
> with the patch applied.
> ---
>  drivers/net/usb/lan78xx.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
> index 5655941f1478..7ac263454d45 100644
> --- a/drivers/net/usb/lan78xx.c
> +++ b/drivers/net/usb/lan78xx.c
> @@ -1719,6 +1719,8 @@ static int lan78xx_ethtool_set_eeprom(struct net_device *netdev,
>  		 (ee->len == 512) &&
>  		 (data[0] == OTP_INDICATOR_1))
>  		ret = lan78xx_write_raw_otp(dev, ee->offset, ee->len, data);
> +	else
> +		ret = -EINVAL;

It might be the nested if's without {} which caused the broken patch?

Maybe add some brackets to make it clearer?

      Andrew