Re: [PATCH v2] drivers/base: Introduce device_match_t for device finding APIs

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

On Sun, Aug 11, 2024 at 10:15:16AM +0800, Zijun Hu wrote:
> From: Zijun Hu <quic_zijuhu@quicinc.com>
> 
> There are several drivers/base APIs for finding a specific device, and
> they currently use the following good type for the @match parameter:
> int (*match)(struct device *dev, const void *data)
> 
> Since these operations do not modify the caller-provided @*data, this
> type is worthy of a dedicated typedef:
> typedef int (*device_match_t)(struct device *dev, const void *data)
> 
> Advantages of using device_match_t:
>  - Shorter API declarations and definitions
>  - Prevent further APIs from using a bad type for @match
> 
> So introduce device_match_t and apply it to the existing
> (bus|class|driver|auxiliary)_find_device() APIs.
> 
> Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
> ---
> Changes in v2:
> - Git rebase over the following commit:
>   bfa54a793ba7 ("driver core: bus: Fix double free in driver API bus_register()")
> - Link to v1: https://lore.kernel.org/r/20240802-dev_match_api-v1-1-51e16d3bf031@quicinc.com
> ---
>  drivers/base/auxiliary.c      | 2 +-
>  drivers/base/bus.c            | 2 +-
>  drivers/base/class.c          | 3 +--
>  drivers/base/driver.c         | 2 +-
>  include/linux/auxiliary_bus.h | 2 +-
>  include/linux/device/bus.h    | 5 +++--
>  include/linux/device/class.h  | 2 +-
>  include/linux/device/driver.h | 2 +-
>  8 files changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/base/auxiliary.c b/drivers/base/auxiliary.c
> index 54b92839e05c..7823888af4f6 100644
> --- a/drivers/base/auxiliary.c
> +++ b/drivers/base/auxiliary.c
> @@ -352,7 +352,7 @@ EXPORT_SYMBOL_GPL(__auxiliary_device_add);
>   */
>  struct auxiliary_device *auxiliary_find_device(struct device *start,
>  					       const void *data,
> -					       int (*match)(struct device *dev, const void *data))
> +					       device_match_t match)
>  {
>  	struct device *dev;
>  
> diff --git a/drivers/base/bus.c b/drivers/base/bus.c
> index abf090ace833..657c93c38b0d 100644
> --- a/drivers/base/bus.c
> +++ b/drivers/base/bus.c
> @@ -391,7 +391,7 @@ EXPORT_SYMBOL_GPL(bus_for_each_dev);
>   */
>  struct device *bus_find_device(const struct bus_type *bus,
>  			       struct device *start, const void *data,
> -			       int (*match)(struct device *dev, const void *data))
> +			       device_match_t match)
>  {
>  	struct subsys_private *sp = bus_to_subsys(bus);
>  	struct klist_iter i;
> diff --git a/drivers/base/class.c b/drivers/base/class.c
> index 7b38fdf8e1d7..ae22fa992c04 100644
> --- a/drivers/base/class.c
> +++ b/drivers/base/class.c
> @@ -433,8 +433,7 @@ EXPORT_SYMBOL_GPL(class_for_each_device);
>   * code.  There's no locking restriction.
>   */
>  struct device *class_find_device(const struct class *class, const struct device *start,
> -				 const void *data,
> -				 int (*match)(struct device *, const void *))
> +				 const void *data, device_match_t match)
>  {
>  	struct subsys_private *sp = class_to_subsys(class);
>  	struct class_dev_iter iter;
> diff --git a/drivers/base/driver.c b/drivers/base/driver.c
> index 88c6fd1f1992..b4eb5b89c4ee 100644
> --- a/drivers/base/driver.c
> +++ b/drivers/base/driver.c
> @@ -150,7 +150,7 @@ EXPORT_SYMBOL_GPL(driver_for_each_device);
>   */
>  struct device *driver_find_device(const struct device_driver *drv,
>  				  struct device *start, const void *data,
> -				  int (*match)(struct device *dev, const void *data))
> +				  device_match_t match)
>  {
>  	struct klist_iter i;
>  	struct device *dev;
> diff --git a/include/linux/auxiliary_bus.h b/include/linux/auxiliary_bus.h
> index 662b8ae54b6a..31762324bcc9 100644
> --- a/include/linux/auxiliary_bus.h
> +++ b/include/linux/auxiliary_bus.h
> @@ -271,6 +271,6 @@ void auxiliary_driver_unregister(struct auxiliary_driver *auxdrv);
>  
>  struct auxiliary_device *auxiliary_find_device(struct device *start,
>  					       const void *data,
> -					       int (*match)(struct device *dev, const void *data));
> +					       device_match_t match);
>  
>  #endif /* _AUXILIARY_BUS_H_ */
> diff --git a/include/linux/device/bus.h b/include/linux/device/bus.h
> index 807831d6bf0f..970de5ee5562 100644
> --- a/include/linux/device/bus.h
> +++ b/include/linux/device/bus.h
> @@ -126,6 +126,8 @@ struct bus_attribute {
>  int __must_check bus_create_file(const struct bus_type *bus, struct bus_attribute *attr);
>  void bus_remove_file(const struct bus_type *bus, struct bus_attribute *attr);
>  
> +/* Matching function type for drivers/base APIs to find a specific device */
> +typedef int (*device_match_t)(struct device *dev, const void *data);
>  /* Generic device matching functions that all busses can use to match with */

Extra new-line after the typedef please.

And shouldn't this be in device.h instead?

thanks,

greg k-h