Re: [PATCH v2 21/21] drm: Remove obsolete GEM and PRIME callbacks from struct drm_driver

From: Thomas Zimmermann <tzimmermann@suse.de>
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Subject: Re: [PATCH v2 21/21] drm: Remove obsolete GEM and PRIME callbacks from struct drm_driver
Date: Wed, 16 Sep 2020 19:55:43 +0200	[thread overview]
Message-ID: <7018b84a-fab6-4277-955b-10871be17204@suse.de> (raw)
In-Reply-To: <20200915145958.19993-22-tzimmermann@suse.de>

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Am 15.09.20 um 16:59 schrieb Thomas Zimmermann:
> Several GEM and PRIME callbacks have been deprecated in favor of
> per-instance GEM object functions. Remove the callbacks as they are
> now unused. The only exception is .gem_prime_mmap, which is still
> in use by several drivers.
> 
> What is also gone is gem_vm_ops in struct drm_driver. All drivers now
> use struct drm_gem_object_funcs.vm_ops instead.
> 
> While at it, the patch also improves error handling around calls
> to .free and .get_sg_table callbacks.
> 
> v2:
> 	* update related TODO item (Sam)
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>  Documentation/gpu/todo.rst           |  7 +--
>  drivers/gpu/drm/drm_gem.c            | 35 +++---------
>  drivers/gpu/drm/drm_gem_cma_helper.c |  6 +-
>  drivers/gpu/drm/drm_prime.c          | 17 +++---
>  include/drm/drm_drv.h                | 85 ++--------------------------
>  5 files changed, 25 insertions(+), 125 deletions(-)
> 
> diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
> index b0ea17da8ff6..0fc6bc222392 100644
> --- a/Documentation/gpu/todo.rst
> +++ b/Documentation/gpu/todo.rst
> @@ -289,11 +289,8 @@ struct drm_gem_object_funcs
>  ---------------------------
>  
>  GEM objects can now have a function table instead of having the callbacks on the
> -DRM driver struct. This is now the preferred way and drivers can be moved over.
> -
> -We also need a 2nd version of the CMA define that doesn't require the
> -vmapping to be present (different hook for prime importing). Plus this needs to
> -be rolled out to all drivers using their own implementations, too.
> +DRM driver struct. This is now the preferred way. Callbacks in drivers have been
> +converted, except for struct drm_driver.gem_prime_mmap.
>  
>  Level: Intermediate
>  
> diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
> index 19d73868490e..96945bed8291 100644
> --- a/drivers/gpu/drm/drm_gem.c
> +++ b/drivers/gpu/drm/drm_gem.c
> @@ -247,12 +247,9 @@ drm_gem_object_release_handle(int id, void *ptr, void *data)
>  {
>  	struct drm_file *file_priv = data;
>  	struct drm_gem_object *obj = ptr;
> -	struct drm_device *dev = obj->dev;
>  
>  	if (obj->funcs && obj->funcs->close)
>  		obj->funcs->close(obj, file_priv);
> -	else if (dev->driver->gem_close_object)
> -		dev->driver->gem_close_object(obj, file_priv);
>  
>  	drm_gem_remove_prime_handles(obj, file_priv);
>  	drm_vma_node_revoke(&obj->vma_node, file_priv);
> @@ -407,10 +404,6 @@ drm_gem_handle_create_tail(struct drm_file *file_priv,
>  		ret = obj->funcs->open(obj, file_priv);
>  		if (ret)
>  			goto err_revoke;
> -	} else if (dev->driver->gem_open_object) {
> -		ret = dev->driver->gem_open_object(obj, file_priv);
> -		if (ret)
> -			goto err_revoke;
>  	}
>  
>  	*handlep = handle;
> @@ -982,12 +975,11 @@ drm_gem_object_free(struct kref *kref)
>  {
>  	struct drm_gem_object *obj =
>  		container_of(kref, struct drm_gem_object, refcount);
> -	struct drm_device *dev = obj->dev;
>  
> -	if (obj->funcs)
> -		obj->funcs->free(obj);
> -	else if (dev->driver->gem_free_object_unlocked)
> -		dev->driver->gem_free_object_unlocked(obj);
> +	if (drm_WARN_ON_ONCE(obj->dev, !obj->funcs || !obj->funcs->free))
> +		return;
> +
> +	obj->funcs->free(obj);
>  }
>  EXPORT_SYMBOL(drm_gem_object_free);
>  
> @@ -1049,9 +1041,9 @@ EXPORT_SYMBOL(drm_gem_vm_close);
>   * @obj_size: the object size to be mapped, in bytes
>   * @vma: VMA for the area to be mapped
>   *
> - * Set up the VMA to prepare mapping of the GEM object using the gem_vm_ops
> - * provided by the driver. Depending on their requirements, drivers can either
> - * provide a fault handler in their gem_vm_ops (in which case any accesses to
> + * Set up the VMA to prepare mapping of the GEM object using the GEM object's
> + * vm_ops. Depending on their requirements, GEM objects can either
> + * provide a fault handler in their vm_ops (in which case any accesses to
>   * the object will be trapped, to perform migration, GTT binding, surface
>   * register allocation, or performance monitoring), or mmap the buffer memory
>   * synchronously after calling drm_gem_mmap_obj.
> @@ -1065,12 +1057,11 @@ EXPORT_SYMBOL(drm_gem_vm_close);
>   * callers must verify access restrictions before calling this helper.
>   *
>   * Return 0 or success or -EINVAL if the object size is smaller than the VMA
> - * size, or if no gem_vm_ops are provided.
> + * size, or if no vm_ops are provided.
>   */
>  int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,
>  		     struct vm_area_struct *vma)
>  {
> -	struct drm_device *dev = obj->dev;
>  	int ret;
>  
>  	/* Check for valid size. */
> @@ -1095,8 +1086,6 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,
>  	} else {
>  		if (obj->funcs && obj->funcs->vm_ops)
>  			vma->vm_ops = obj->funcs->vm_ops;
> -		else if (dev->driver->gem_vm_ops)
> -			vma->vm_ops = dev->driver->gem_vm_ops;
>  		else {
>  			drm_gem_object_put(obj);
>  			return -EINVAL;
> @@ -1206,8 +1195,6 @@ int drm_gem_pin(struct drm_gem_object *obj)
>  {
>  	if (obj->funcs && obj->funcs->pin)
>  		return obj->funcs->pin(obj);
> -	else if (obj->dev->driver->gem_prime_pin)
> -		return obj->dev->driver->gem_prime_pin(obj);
>  	else
>  		return 0;
>  }
> @@ -1216,8 +1203,6 @@ void drm_gem_unpin(struct drm_gem_object *obj)
>  {
>  	if (obj->funcs && obj->funcs->unpin)
>  		obj->funcs->unpin(obj);
> -	else if (obj->dev->driver->gem_prime_unpin)
> -		obj->dev->driver->gem_prime_unpin(obj);
>  }
>  
>  void *drm_gem_vmap(struct drm_gem_object *obj)
> @@ -1226,8 +1211,6 @@ void *drm_gem_vmap(struct drm_gem_object *obj)
>  
>  	if (obj->funcs && obj->funcs->vmap)
>  		vaddr = obj->funcs->vmap(obj);
> -	else if (obj->dev->driver->gem_prime_vmap)
> -		vaddr = obj->dev->driver->gem_prime_vmap(obj);
>  	else
>  		vaddr = ERR_PTR(-EOPNOTSUPP);
>  
> @@ -1244,8 +1227,6 @@ void drm_gem_vunmap(struct drm_gem_object *obj, void *vaddr)
>  
>  	if (obj->funcs && obj->funcs->vunmap)
>  		obj->funcs->vunmap(obj, vaddr);
> -	else if (obj->dev->driver->gem_prime_vunmap)
> -		obj->dev->driver->gem_prime_vunmap(obj, vaddr);
>  }
>  
>  /**
> diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
> index 822edeadbab3..209202257cc2 100644
> --- a/drivers/gpu/drm/drm_gem_cma_helper.c
> +++ b/drivers/gpu/drm/drm_gem_cma_helper.c
> @@ -419,7 +419,7 @@ EXPORT_SYMBOL(drm_gem_cma_print_info);
>   *
>   * This function exports a scatter/gather table suitable for PRIME usage by
>   * calling the standard DMA mapping API. Drivers using the CMA helpers should
> - * set this as their &drm_driver.gem_prime_get_sg_table callback.
> + * set this as their &drm_gem_object_funcs.get_sg_table callback.
>   *
>   * Returns:
>   * A pointer to the scatter/gather table of pinned pages or NULL on failure.
> @@ -542,7 +542,7 @@ EXPORT_SYMBOL_GPL(drm_gem_cma_prime_mmap);
>   * virtual address space. Since the CMA buffers are already mapped into the
>   * kernel virtual address space this simply returns the cached virtual
>   * address. Drivers using the CMA helpers should set this as their DRM
> - * driver's &drm_driver.gem_prime_vmap callback.
> + * driver's &drm_gem_object_funcs.vmap callback.
>   *
>   * Returns:
>   * The kernel virtual address of the CMA GEM object's backing store.
> @@ -564,7 +564,7 @@ EXPORT_SYMBOL_GPL(drm_gem_cma_prime_vmap);
>   * This function removes a buffer exported via DRM PRIME from the kernel's
>   * virtual address space. This is a no-op because CMA buffers cannot be
>   * unmapped from kernel space. Drivers using the CMA helpers should set this
> - * as their &drm_driver.gem_prime_vunmap callback.
> + * as their &drm_gem_object_funcs.vunmap callback.
>   */
>  void drm_gem_cma_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
>  {
> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
> index 8a6a3c99b7d8..1cffb004d3c8 100644
> --- a/drivers/gpu/drm/drm_prime.c
> +++ b/drivers/gpu/drm/drm_prime.c
> @@ -386,10 +386,6 @@ static struct dma_buf *export_and_register_object(struct drm_device *dev,
>  
>  	if (obj->funcs && obj->funcs->export)
>  		dmabuf = obj->funcs->export(obj, flags);
> -	else if (dev->driver->gem_prime_export)
> -		dmabuf = dev->driver->gem_prime_export(obj, flags);

> -	else
> -		dmabuf = drm_gem_prime_export(obj, flags);

Oops, these two lines were not supposed to be removed. They'll return in
v3 of the patchset. That will also fix the error report that was posted
by the CI. [1]

Best regards
Thomas

[1]
https://lore.kernel.org/intel-gfx/160018797587.30601.1382075328491651866@emeril.freedesktop.org/

>  	if (IS_ERR(dmabuf)) {
>  		/* normally the created dma-buf takes ownership of the ref,
>  		 * but if that fails then drop the ref
> @@ -419,7 +415,7 @@ static struct dma_buf *export_and_register_object(struct drm_device *dev,
>   * This is the PRIME export function which must be used mandatorily by GEM
>   * drivers to ensure correct lifetime management of the underlying GEM object.
>   * The actual exporting from GEM object to a dma-buf is done through the
> - * &drm_driver.gem_prime_export driver callback.
> + * &drm_gem_object_funcs.export callback.
>   */
>  int drm_gem_prime_handle_to_fd(struct drm_device *dev,
>  			       struct drm_file *file_priv, uint32_t handle,
> @@ -616,15 +612,18 @@ struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
>  				     enum dma_data_direction dir)
>  {
>  	struct drm_gem_object *obj = attach->dmabuf->priv;
> -	struct sg_table *sgt;
> +	struct sg_table *sgt = NULL;
>  
>  	if (WARN_ON(dir == DMA_NONE))
>  		return ERR_PTR(-EINVAL);
>  
> -	if (obj->funcs)
> +	if (obj->funcs && obj->funcs->get_sg_table)
>  		sgt = obj->funcs->get_sg_table(obj);
> -	else
> -		sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
> +
> +	if (!sgt)
> +		return ERR_PTR(-EINVAL);
> +	else if (IS_ERR(sgt))
> +		return sgt;
>  
>  	if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
>  			      DMA_ATTR_SKIP_CPU_SYNC)) {
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index 9b11a2f0babc..240b0eab8018 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -36,10 +36,12 @@ struct drm_file;
>  struct drm_gem_object;
>  struct drm_master;
>  struct drm_minor;
> +struct dma_buf;
>  struct dma_buf_attachment;
>  struct drm_display_mode;
>  struct drm_mode_create_dumb;
>  struct drm_printer;
> +struct sg_table;
>  
>  /**
>   * enum drm_driver_feature - feature flags
> @@ -326,32 +328,6 @@ struct drm_driver {
>  	 */
>  	void (*debugfs_init)(struct drm_minor *minor);
>  
> -	/**
> -	 * @gem_free_object_unlocked: deconstructor for drm_gem_objects
> -	 *
> -	 * This is deprecated and should not be used by new drivers. Use
> -	 * &drm_gem_object_funcs.free instead.
> -	 */
> -	void (*gem_free_object_unlocked) (struct drm_gem_object *obj);
> -
> -	/**
> -	 * @gem_open_object:
> -	 *
> -	 * This callback is deprecated in favour of &drm_gem_object_funcs.open.
> -	 *
> -	 * Driver hook called upon gem handle creation
> -	 */
> -	int (*gem_open_object) (struct drm_gem_object *, struct drm_file *);
> -
> -	/**
> -	 * @gem_close_object:
> -	 *
> -	 * This callback is deprecated in favour of &drm_gem_object_funcs.close.
> -	 *
> -	 * Driver hook called upon gem handle release
> -	 */
> -	void (*gem_close_object) (struct drm_gem_object *, struct drm_file *);
> -
>  	/**
>  	 * @gem_create_object: constructor for gem objects
>  	 *
> @@ -360,6 +336,7 @@ struct drm_driver {
>  	 */
>  	struct drm_gem_object *(*gem_create_object)(struct drm_device *dev,
>  						    size_t size);
> +
>  	/**
>  	 * @prime_handle_to_fd:
>  	 *
> @@ -382,14 +359,7 @@ struct drm_driver {
>  	 */
>  	int (*prime_fd_to_handle)(struct drm_device *dev, struct drm_file *file_priv,
>  				int prime_fd, uint32_t *handle);
> -	/**
> -	 * @gem_prime_export:
> -	 *
> -	 * Export hook for GEM drivers. Deprecated in favour of
> -	 * &drm_gem_object_funcs.export.
> -	 */
> -	struct dma_buf * (*gem_prime_export)(struct drm_gem_object *obj,
> -					     int flags);
> +
>  	/**
>  	 * @gem_prime_import:
>  	 *
> @@ -399,29 +369,6 @@ struct drm_driver {
>  	 */
>  	struct drm_gem_object * (*gem_prime_import)(struct drm_device *dev,
>  				struct dma_buf *dma_buf);
> -
> -	/**
> -	 * @gem_prime_pin:
> -	 *
> -	 * Deprecated hook in favour of &drm_gem_object_funcs.pin.
> -	 */
> -	int (*gem_prime_pin)(struct drm_gem_object *obj);
> -
> -	/**
> -	 * @gem_prime_unpin:
> -	 *
> -	 * Deprecated hook in favour of &drm_gem_object_funcs.unpin.
> -	 */
> -	void (*gem_prime_unpin)(struct drm_gem_object *obj);
> -
> -
> -	/**
> -	 * @gem_prime_get_sg_table:
> -	 *
> -	 * Deprecated hook in favour of &drm_gem_object_funcs.get_sg_table.
> -	 */
> -	struct sg_table *(*gem_prime_get_sg_table)(struct drm_gem_object *obj);
> -
>  	/**
>  	 * @gem_prime_import_sg_table:
>  	 *
> @@ -432,22 +379,6 @@ struct drm_driver {
>  				struct drm_device *dev,
>  				struct dma_buf_attachment *attach,
>  				struct sg_table *sgt);
> -	/**
> -	 * @gem_prime_vmap:
> -	 *
> -	 * Deprecated vmap hook for GEM drivers. Please use
> -	 * &drm_gem_object_funcs.vmap instead.
> -	 */
> -	void *(*gem_prime_vmap)(struct drm_gem_object *obj);
> -
> -	/**
> -	 * @gem_prime_vunmap:
> -	 *
> -	 * Deprecated vunmap hook for GEM drivers. Please use
> -	 * &drm_gem_object_funcs.vunmap instead.
> -	 */
> -	void (*gem_prime_vunmap)(struct drm_gem_object *obj, void *vaddr);
> -
>  	/**
>  	 * @gem_prime_mmap:
>  	 *
> @@ -522,14 +453,6 @@ struct drm_driver {
>  			    struct drm_device *dev,
>  			    uint32_t handle);
>  
> -	/**
> -	 * @gem_vm_ops: Driver private ops for this object
> -	 *
> -	 * For GEM drivers this is deprecated in favour of
> -	 * &drm_gem_object_funcs.vm_ops.
> -	 */
> -	const struct vm_operations_struct *gem_vm_ops;
> -
>  	/** @major: driver major number */
>  	int major;
>  	/** @minor: driver minor number */
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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