[PATCH RFC v4 01/16] drm: Add drm_minor_for_each

[Daniel Vetter]

On Thu, Aug 29, 2019 at 02:05:18AM -0400, Kenny Ho wrote:
> To allow other subsystems to iterate through all stored DRM minors and
> act upon them.
> 
> Also exposes drm_minor_acquire and drm_minor_release for other subsystem
> to handle drm_minor.  DRM cgroup controller is the initial consumer of
> this new features.
> 
> Change-Id: I7c4b67ce6b31f06d1037b03435386ff5b8144ca5
> Signed-off-by: Kenny Ho <Kenny.Ho at amd.com>

Iterating over minors for cgroups sounds very, very wrong. Why do we care
whether a buffer was allocated through kms dumb vs render nodes?

I'd expect all the cgroup stuff to only work on drm_device, if it does
care about devices.

(I didn't look through the patch series to find out where exactly you're
using this, so maybe I'm off the rails here).
-Daniel

> ---
>  drivers/gpu/drm/drm_drv.c      | 19 +++++++++++++++++++
>  drivers/gpu/drm/drm_internal.h |  4 ----
>  include/drm/drm_drv.h          |  4 ++++
>  3 files changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 862621494a93..000cddabd970 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -254,11 +254,13 @@ struct drm_minor *drm_minor_acquire(unsigned int minor_id)
>  
>  	return minor;
>  }
> +EXPORT_SYMBOL(drm_minor_acquire);
>  
>  void drm_minor_release(struct drm_minor *minor)
>  {
>  	drm_dev_put(minor->dev);
>  }
> +EXPORT_SYMBOL(drm_minor_release);
>  
>  /**
>   * DOC: driver instance overview
> @@ -1078,6 +1080,23 @@ int drm_dev_set_unique(struct drm_device *dev, const char *name)
>  }
>  EXPORT_SYMBOL(drm_dev_set_unique);
>  
> +/**
> + * drm_minor_for_each - Iterate through all stored DRM minors
> + * @fn: Function to be called for each pointer.
> + * @data: Data passed to callback function.
> + *
> + * The callback function will be called for each @drm_minor entry, passing
> + * the minor, the entry and @data.
> + *
> + * If @fn returns anything other than %0, the iteration stops and that
> + * value is returned from this function.
> + */
> +int drm_minor_for_each(int (*fn)(int id, void *p, void *data), void *data)
> +{
> +	return idr_for_each(&drm_minors_idr, fn, data);
> +}
> +EXPORT_SYMBOL(drm_minor_for_each);
> +
>  /*
>   * DRM Core
>   * The DRM core module initializes all global DRM objects and makes them
> diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
> index e19ac7ca602d..6bfad76f8e78 100644
> --- a/drivers/gpu/drm/drm_internal.h
> +++ b/drivers/gpu/drm/drm_internal.h
> @@ -54,10 +54,6 @@ void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv);
>  void drm_prime_remove_buf_handle_locked(struct drm_prime_file_private *prime_fpriv,
>  					struct dma_buf *dma_buf);
>  
> -/* drm_drv.c */
> -struct drm_minor *drm_minor_acquire(unsigned int minor_id);
> -void drm_minor_release(struct drm_minor *minor);
> -
>  /* drm_vblank.c */
>  void drm_vblank_disable_and_save(struct drm_device *dev, unsigned int pipe);
>  void drm_vblank_cleanup(struct drm_device *dev);
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index 68ca736c548d..24f8d054c570 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -799,5 +799,9 @@ static inline bool drm_drv_uses_atomic_modeset(struct drm_device *dev)
>  
>  int drm_dev_set_unique(struct drm_device *dev, const char *name);
>  
> +int drm_minor_for_each(int (*fn)(int id, void *p, void *data), void *data);
> +
> +struct drm_minor *drm_minor_acquire(unsigned int minor_id);
> +void drm_minor_release(struct drm_minor *minor);
>  
>  #endif
> -- 
> 2.22.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch