Re: [PATCH 1/2] driver: core: Allow drivers to opt out of driver_override

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Sep 22, 2026 at 01:38:28PM +0200, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> Some drivers rely on device data obtained through device ID matching and
> will not work otherwise. Some such drivers don't check for the validity
> of the device data because it is never NULL when the device is matched
> against the device ID table.
> 
> However, Uwe recently pointed out that drivers always need to check this
> device data because any device can be forced to bind against a driver if
> their driver_override sysfs attribute is set and the driver rebound. Any
> such device will now not have device data from a device ID match table
> and may crash.
> 
> Add a flag that allows drivers to opt out of the override mechanism when
> it doesn't make sense. This allows us to deal with these situations in
> the core rather than sprinkle checks throughout all of these drivers to
> check for validity of the device data.
> 
> Cc: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>  include/linux/device.h        | 12 +++++++++---
>  include/linux/device/driver.h | 12 ++++++++++++
>  2 files changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 90cdd77458bb..45c23cc5efa8 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -899,14 +899,20 @@ static inline bool device_has_driver_override(struct device *dev)
>   *
>   * Returns > 0 if a driver override is set and matches the given driver, 0 if a
>   * driver override is set but does not match, or < 0 if a driver override is not
> - * set at all.
> + * set at all or the driver opts out of the override mechanism.

What's wrong with just not allowing bind/unbind at all?  Why would you
want that, but NOT the driver_override file?

thanks,

greg k-h