Re: [PATCH RESEND] drm/bridge: drm_bridge_get/put(): document NULL pointer behaviour

["Luca Ceresoli" <luca.ceresoli@bootlin.com>]

Hello Liu,

On Thu Mar 26, 2026 at 10:36 AM CET, Liu Ying wrote:

>> --- a/drivers/gpu/drm/drm_bridge.c
>> +++ b/drivers/gpu/drm/drm_bridge.c
>> @@ -282,7 +282,7 @@ static void __drm_bridge_free(struct kref *kref)
>>
>>  /**
>>   * drm_bridge_get - Acquire a bridge reference
>> - * @bridge: DRM bridge
>> + * @bridge: DRM bridge; if NULL this function does nothing
>>   *
>>   * This function increments the bridge's refcount.
>>   *
>> @@ -300,7 +300,7 @@ EXPORT_SYMBOL(drm_bridge_get);
>>
>>  /**
>>   * drm_bridge_put - Release a bridge reference
>> - * @bridge: DRM bridge
>> + * @bridge: DRM bridge; if NULL this function does nothing
>
> So, we can drop the if(_T) check for cleanup action, right?

We could, but it's supposed to be there to help compiler optimizations:
https://elixir.bootlin.com/linux/v7.0-rc5/source/include/linux/cleanup.h#L192-L207

> DEFINE_FREE(drm_bridge_put, struct drm_bridge *, if (_T) drm_bridge_put(_T))
>
> Reviewed-by: Liu Ying <victor.liu@nxp.com>

Thanks!

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com