Subject: [PATCH v3] dma-buf: cleanup dma_buf_export() to make it easily extensible

From: [email-masked] (Maarten Lankhorst)
Date: Wed, 28 Jan 2015 16:00:12 +0100

Op 28-01-15 om 13:54 schreef Sumit Semwal:
> At present, dma_buf_export() takes a series of parameters, which
> makes it difficult to add any new parameters for exporters, if required.
>
> Make it simpler by moving all these parameters into a struct, and pass
> the struct * as parameter to dma_buf_export().
>
> While at it, unite dma_buf_export_named() with dma_buf_export(), and
> change all callers accordingly.
>
> Signed-off-by: Sumit Semwal <[email-masked]>
> ---
> v3: Daniel Thompson caught the C99 warning issue w/ using {0}; using
>     {.exp_name = xxx} instead.
>
> v2: add macro to zero out local struct, and fill KBUILD_MODNAME by default
>
>  drivers/dma-buf/dma-buf.c                      | 47 +++++++++++++-------------
>  drivers/gpu/drm/armada/armada_gem.c            | 10 ++++--
>  drivers/gpu/drm/drm_prime.c                    | 12 ++++---
>  drivers/gpu/drm/exynos/exynos_drm_dmabuf.c     |  9 +++--
>  drivers/gpu/drm/i915/i915_gem_dmabuf.c         | 10 ++++--
>  drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c      |  9 ++++-
>  drivers/gpu/drm/tegra/gem.c                    | 10 ++++--
>  drivers/gpu/drm/ttm/ttm_object.c               |  9 +++--
>  drivers/gpu/drm/udl/udl_dmabuf.c               |  9 ++++-
>  drivers/media/v4l2-core/videobuf2-dma-contig.c |  8 ++++-
>  drivers/media/v4l2-core/videobuf2-dma-sg.c     |  8 ++++-
>  drivers/media/v4l2-core/videobuf2-vmalloc.c    |  8 ++++-
>  drivers/staging/android/ion/ion.c              |  9 +++--
>  include/linux/dma-buf.h                        | 34 +++++++++++++++----
>  14 files changed, 142 insertions(+), 50 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 5be225c2ba98..6d3df3dd9310 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -265,7 +265,7 @@ static inline int is_dma_buf_file(struct file *file)
>  }
>  
>  /**
> - * dma_buf_export_named - Creates a new dma_buf, and associates an anon file
> + * dma_buf_export - Creates a new dma_buf, and associates an anon file
>   * with this buffer, so it can be exported.
>   * Also connect the allocator specific data and ops to the buffer.
>   * Additionally, provide a name string for exporter; useful in debugging.
> @@ -277,31 +277,32 @@ static inline int is_dma_buf_file(struct file *file)
>   * @exp_name:	[in]	name of the exporting module - useful for debugging.
>   * @resv:	[in]	reservation-object, NULL to allocate default one.
>   *
> + * All the above info comes from struct dma_buf_export_info.
> + *
>   * Returns, on success, a newly created dma_buf object, which wraps the
>   * supplied private data and operations for dma_buf_ops. On either missing
>   * ops, or error in allocating struct dma_buf, will return negative error.
>   *
>   */
> -struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops,
> -				size_t size, int flags, const char *exp_name,
> -				struct reservation_object *resv)
> +struct dma_buf *dma_buf_export(struct dma_buf_export_info *exp_info)
This function should probably take a const struct dma_buf_export_info here..

Rest looks sane.

~Maarten

>  {
>  	struct dma_buf *dmabuf;
>  	struct file *file;
>  	size_t alloc_size = sizeof(struct dma_buf);
> -	if (!resv)
> +	if (!exp_info->resv)
>  		alloc_size += sizeof(struct reservation_object);
>  	else
>  		/* prevent &dma_buf[1] == dma_buf->resv */
>  		alloc_size += 1;
>  
> -	if (WARN_ON(!priv || !ops
> -			  || !ops->map_dma_buf
> -			  || !ops->unmap_dma_buf
> -			  || !ops->release
> -			  || !ops->kmap_atomic
> -			  || !ops->kmap
> -			  || !ops->mmap)) {
> +	if (WARN_ON(!exp_info->priv
> +			  || !exp_info->ops
> +			  || !exp_info->ops->map_dma_buf
> +			  || !exp_info->ops->unmap_dma_buf
> +			  || !exp_info->ops->release
> +			  || !exp_info->ops->kmap_atomic
> +			  || !exp_info->ops->kmap
> +			  || !exp_info->ops->mmap)) {
>  		return ERR_PTR(-EINVAL);
>  	}
>  
> @@ -309,21 +310,22 @@ struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops,
>  	if (dmabuf == NULL)
>  		return ERR_PTR(-ENOMEM);
>  
> -	dmabuf->priv = priv;
> -	dmabuf->ops = ops;
> -	dmabuf->size = size;
> -	dmabuf->exp_name = exp_name;
> +	dmabuf->priv = exp_info->priv;
> +	dmabuf->ops = exp_info->ops;
> +	dmabuf->size = exp_info->size;
> +	dmabuf->exp_name = exp_info->exp_name;
>  	init_waitqueue_head(&dmabuf->poll);
>  	dmabuf->cb_excl.poll = dmabuf->cb_shared.poll = &dmabuf->poll;
>  	dmabuf->cb_excl.active = dmabuf->cb_shared.active = 0;
>  
> -	if (!resv) {
> -		resv = (struct reservation_object *)&dmabuf[1];
> -		reservation_object_init(resv);
> +	if (!exp_info->resv) {
> +		exp_info->resv = (struct reservation_object *)&dmabuf[1];
> +		reservation_object_init(exp_info->resv);
>  	}
> -	dmabuf->resv = resv;
> +	dmabuf->resv = exp_info->resv;
>  
> -	file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
> +	file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf,
> +					exp_info->flags);
>  	if (IS_ERR(file)) {
>  		kfree(dmabuf);
>  		return ERR_CAST(file);
> @@ -341,8 +343,7 @@ struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops,
>  
>  	return dmabuf;
>  }
> -EXPORT_SYMBOL_GPL(dma_buf_export_named);
> -
> +EXPORT_SYMBOL_GPL(dma_buf_export);
>  
>  /**
>   * dma_buf_fd - returns a file descriptor for the given dma_buf
> diff --git a/drivers/gpu/drm/armada/armada_gem.c b/drivers/gpu/drm/armada/armada_gem.c
> index ef5feeecec84..580e10acaa3a 100644
> --- a/drivers/gpu/drm/armada/armada_gem.c
> +++ b/drivers/gpu/drm/armada/armada_gem.c
> @@ -538,8 +538,14 @@ struct dma_buf *
>  armada_gem_prime_export(struct drm_device *dev, struct drm_gem_object *obj,
>  	int flags)
>  {
> -	return dma_buf_export(obj, &armada_gem_prime_dmabuf_ops, obj->size,
> -			      O_RDWR, NULL);
> +	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> +
> +	exp_info.ops = &armada_gem_prime_dmabuf_ops;
> +	exp_info.size = obj->size;
> +	exp_info.flags = O_RDWR;
> +	exp_info.priv = obj;
> +
> +	return dma_buf_export(&exp_info);
>  }
>  
>  struct drm_gem_object *
> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
> index 7482b06cd08f..7fec191b45f7 100644
> --- a/drivers/gpu/drm/drm_prime.c
> +++ b/drivers/gpu/drm/drm_prime.c
> @@ -339,13 +339,17 @@ static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
>  struct dma_buf *drm_gem_prime_export(struct drm_device *dev,
>  				     struct drm_gem_object *obj, int flags)
>  {
> -	struct reservation_object *robj = NULL;
> +	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> +
> +	exp_info.ops = &drm_gem_prime_dmabuf_ops;
> +	exp_info.size = obj->size;
> +	exp_info.flags = flags;
> +	exp_info.priv = obj;
>  
>  	if (dev->driver->gem_prime_res_obj)
> -		robj = dev->driver->gem_prime_res_obj(obj);
> +		exp_info.resv = dev->driver->gem_prime_res_obj(obj);
>  
> -	return dma_buf_export(obj, &drm_gem_prime_dmabuf_ops, obj->size,
> -			      flags, robj);
> +	return dma_buf_export(&exp_info);
>  }
>  EXPORT_SYMBOL(drm_gem_prime_export);
>  
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
> index 60192ed544f0..fc293a179f36 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
> @@ -185,9 +185,14 @@ struct dma_buf *exynos_dmabuf_prime_export(struct drm_device *drm_dev,
>  				struct drm_gem_object *obj, int flags)
>  {
>  	struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj);
> +	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
>  
> -	return dma_buf_export(obj, &exynos_dmabuf_ops,
> -				exynos_gem_obj->base.size, flags, NULL);
> +	exp_info.ops = &exynos_dmabuf_ops;
> +	exp_info.size = exynos_gem_obj->base.size;
> +	exp_info.flags = flags;
> +	exp_info.priv = obj;
> +
> +	return dma_buf_export(&exp_info);
>  }
>  
>  struct drm_gem_object *exynos_dmabuf_prime_import(struct drm_device *drm_dev,
> diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> index 82a1f4b57778..7998da27c500 100644
> --- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> +++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> @@ -230,6 +230,13 @@ struct dma_buf *i915_gem_prime_export(struct drm_device *dev,
>  				      struct drm_gem_object *gem_obj, int flags)
>  {
>  	struct drm_i915_gem_object *obj = to_intel_bo(gem_obj);
> +	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> +
> +	exp_info.ops = &i915_dmabuf_ops;
> +	exp_info.size = gem_obj->size;
> +	exp_info.flags = flags;
> +	exp_info.priv = gem_obj;
> +
>  
>  	if (obj->ops->dmabuf_export) {
>  		int ret = obj->ops->dmabuf_export(obj);
> @@ -237,8 +244,7 @@ struct dma_buf *i915_gem_prime_export(struct drm_device *dev,
>  			return ERR_PTR(ret);
>  	}
>  
> -	return dma_buf_export(gem_obj, &i915_dmabuf_ops, gem_obj->size, flags,
> -			      NULL);
> +	return dma_buf_export(&exp_info);
>  }
>  
>  static int i915_gem_object_get_pages_dmabuf(struct drm_i915_gem_object *obj)
> diff --git a/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c b/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
> index a2dbfb1737b4..5874c58e72c1 100644
> --- a/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
> +++ b/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
> @@ -171,7 +171,14 @@ static struct dma_buf_ops omap_dmabuf_ops = {
>  struct dma_buf *omap_gem_prime_export(struct drm_device *dev,
>  		struct drm_gem_object *obj, int flags)
>  {
> -	return dma_buf_export(obj, &omap_dmabuf_ops, obj->size, flags, NULL);
> +	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> +
> +	exp_info.ops = &omap_dmabuf_ops;
> +	exp_info.size = obj->size;
> +	exp_info.flags = flags;
> +	exp_info.priv = obj;
> +
> +	return dma_buf_export(&exp_info);
>  }
>  
>  struct drm_gem_object *omap_gem_prime_import(struct drm_device *dev,
> diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c
> index 8777b7f75791..1f895b953f8f 100644
> --- a/drivers/gpu/drm/tegra/gem.c
> +++ b/drivers/gpu/drm/tegra/gem.c
> @@ -658,8 +658,14 @@ struct dma_buf *tegra_gem_prime_export(struct drm_device *drm,
>  				       struct drm_gem_object *gem,
>  				       int flags)
>  {
> -	return dma_buf_export(gem, &tegra_gem_prime_dmabuf_ops, gem->size,
> -			      flags, NULL);
> +	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> +
> +	exp_info.ops = &tegra_gem_prime_dmabuf_ops;
> +	exp_info.size = gem->size;
> +	exp_info.flags = flags;
> +	exp_info.priv = gem;
> +
> +	return dma_buf_export(&exp_info);
>  }
>  
>  struct drm_gem_object *tegra_gem_prime_import(struct drm_device *drm,
> diff --git a/drivers/gpu/drm/ttm/ttm_object.c b/drivers/gpu/drm/ttm/ttm_object.c
> index 12c87110db3a..4f5fa8d65fe9 100644
> --- a/drivers/gpu/drm/ttm/ttm_object.c
> +++ b/drivers/gpu/drm/ttm/ttm_object.c
> @@ -683,6 +683,12 @@ int ttm_prime_handle_to_fd(struct ttm_object_file *tfile,
>  
>  	dma_buf = prime->dma_buf;
>  	if (!dma_buf || !get_dma_buf_unless_doomed(dma_buf)) {
> +		DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> +
> +		exp_info.ops = &tdev->ops;
> +		exp_info.size = prime->size;
> +		exp_info.flags = flags;
> +		exp_info.priv = prime;
>  
>  		/*
>  		 * Need to create a new dma_buf, with memory accounting.
> @@ -694,8 +700,7 @@ int ttm_prime_handle_to_fd(struct ttm_object_file *tfile,
>  			goto out_unref;
>  		}
>  
> -		dma_buf = dma_buf_export(prime, &tdev->ops,
> -					 prime->size, flags, NULL);
> +		dma_buf = dma_buf_export(&exp_info);
>  		if (IS_ERR(dma_buf)) {
>  			ret = PTR_ERR(dma_buf);
>  			ttm_mem_global_free(tdev->mem_glob,
> diff --git a/drivers/gpu/drm/udl/udl_dmabuf.c b/drivers/gpu/drm/udl/udl_dmabuf.c
> index ac8a66b4dfc2..e2243edd1ce3 100644
> --- a/drivers/gpu/drm/udl/udl_dmabuf.c
> +++ b/drivers/gpu/drm/udl/udl_dmabuf.c
> @@ -202,7 +202,14 @@ static struct dma_buf_ops udl_dmabuf_ops = {
>  struct dma_buf *udl_gem_prime_export(struct drm_device *dev,
>  				     struct drm_gem_object *obj, int flags)
>  {
> -	return dma_buf_export(obj, &udl_dmabuf_ops, obj->size, flags, NULL);
> +	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> +
> +	exp_info.ops = &udl_dmabuf_ops;
> +	exp_info.size = obj->size;
> +	exp_info.flags = flags;
> +	exp_info.priv = obj;
> +
> +	return dma_buf_export(&exp_info);
>  }
>  
>  static int udl_prime_create(struct drm_device *dev,
> diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c
> index b481d20c8372..4ad92a147919 100644
> --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c
> +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c
> @@ -402,6 +402,12 @@ static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv, unsigned long flags)
>  {
>  	struct vb2_dc_buf *buf = buf_priv;
>  	struct dma_buf *dbuf;
> +	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> +
> +	exp_info.ops = &vb2_dc_dmabuf_ops;
> +	exp_info.size = buf->size;
> +	exp_info.flags = flags;
> +	exp_info.priv = buf;
>  
>  	if (!buf->sgt_base)
>  		buf->sgt_base = vb2_dc_get_base_sgt(buf);
> @@ -409,7 +415,7 @@ static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv, unsigned long flags)
>  	if (WARN_ON(!buf->sgt_base))
>  		return NULL;
>  
> -	dbuf = dma_buf_export(buf, &vb2_dc_dmabuf_ops, buf->size, flags, NULL);
> +	dbuf = dma_buf_export(&exp_info);
>  	if (IS_ERR(dbuf))
>  		return NULL;
>  
> diff --git a/drivers/media/v4l2-core/videobuf2-dma-sg.c b/drivers/media/v4l2-core/videobuf2-dma-sg.c
> index b1838abb6d00..45c708e463b9 100644
> --- a/drivers/media/v4l2-core/videobuf2-dma-sg.c
> +++ b/drivers/media/v4l2-core/videobuf2-dma-sg.c
> @@ -583,11 +583,17 @@ static struct dma_buf *vb2_dma_sg_get_dmabuf(void *buf_priv, unsigned long flags
>  {
>  	struct vb2_dma_sg_buf *buf = buf_priv;
>  	struct dma_buf *dbuf;
> +	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> +
> +	exp_info.ops = &vb2_dma_sg_dmabuf_ops;
> +	exp_info.size = buf->size;
> +	exp_info.flags = flags;
> +	exp_info.priv = buf;
>  
>  	if (WARN_ON(!buf->dma_sgt))
>  		return NULL;
>  
> -	dbuf = dma_buf_export(buf, &vb2_dma_sg_dmabuf_ops, buf->size, flags, NULL);
> +	dbuf = dma_buf_export(&exp_info);
>  	if (IS_ERR(dbuf))
>  		return NULL;
>  
> diff --git a/drivers/media/v4l2-core/videobuf2-vmalloc.c b/drivers/media/v4l2-core/videobuf2-vmalloc.c
> index fba944e50227..992b1b59409c 100644
> --- a/drivers/media/v4l2-core/videobuf2-vmalloc.c
> +++ b/drivers/media/v4l2-core/videobuf2-vmalloc.c
> @@ -367,11 +367,17 @@ static struct dma_buf *vb2_vmalloc_get_dmabuf(void *buf_priv, unsigned long flag
>  {
>  	struct vb2_vmalloc_buf *buf = buf_priv;
>  	struct dma_buf *dbuf;
> +	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> +
> +	exp_info.ops = &vb2_vmalloc_dmabuf_ops;
> +	exp_info.size = buf->size;
> +	exp_info.flags = flags;
> +	exp_info.priv = buf;
>  
>  	if (WARN_ON(!buf->vaddr))
>  		return NULL;
>  
> -	dbuf = dma_buf_export(buf, &vb2_vmalloc_dmabuf_ops, buf->size, flags, NULL);
> +	dbuf = dma_buf_export(&exp_info);
>  	if (IS_ERR(dbuf))
>  		return NULL;
>  
> diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
> index 296d347660fc..a4297be8f12f 100644
> --- a/drivers/staging/android/ion/ion.c
> +++ b/drivers/staging/android/ion/ion.c
> @@ -1106,6 +1106,12 @@ struct dma_buf *ion_share_dma_buf(struct ion_client *client,
>  	struct ion_buffer *buffer;
>  	struct dma_buf *dmabuf;
>  	bool valid_handle;
> +	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> +
> +	exp_info.ops = &dma_buf_ops;
> +	exp_info.size = buffer->size;
> +	exp_info.flags = O_RDWR;
> +	exp_info.priv = buffer;
>  
>  	mutex_lock(&client->lock);
>  	valid_handle = ion_handle_validate(client, handle);
> @@ -1118,8 +1124,7 @@ struct dma_buf *ion_share_dma_buf(struct ion_client *client,
>  	ion_buffer_get(buffer);
>  	mutex_unlock(&client->lock);
>  
> -	dmabuf = dma_buf_export(buffer, &dma_buf_ops, buffer->size, O_RDWR,
> -				NULL);
> +	dmabuf = dma_buf_export(&exp_info);
>  	if (IS_ERR(dmabuf)) {
>  		ion_buffer_put(buffer);
>  		return dmabuf;
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index 694e1fe1c4b4..a4e395eeffef 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -163,6 +163,33 @@ struct dma_buf_attachment {
>  };
>  
>  /**
> + * struct dma_buf_export_info - holds information needed to export a dma_buf
> + * @exp_name:	name of the exporting module - useful for debugging.
> + * @ops:	Attach allocator-defined dma buf ops to the new buffer
> + * @size:	Size of the buffer
> + * @flags:	mode flags for the file
> + * @resv:	reservation-object, NULL to allocate default one
> + * @priv:	Attach private data of allocator to this buffer
> + *
> + * This structure holds the information required to export the buffer. Used
> + * with dma_buf_export() only.
> + */
> +struct dma_buf_export_info {
> +	const char *exp_name;
> +	const struct dma_buf_ops *ops;
> +	size_t size;
> +	int flags;
> +	struct reservation_object *resv;
> +	void *priv;
> +};
> +
> +/**
> + * helper macro for exporters; zeros and fills in most common values
> + */
> +#define DEFINE_DMA_BUF_EXPORT_INFO(a)	\
> +	struct dma_buf_export_info a = { .exp_name = KBUILD_MODNAME }
> +
> +/**
>   * get_dma_buf - convenience wrapper for get_file.
>   * @dmabuf:	[in]	pointer to dma_buf
>   *
> @@ -181,12 +208,7 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
>  void dma_buf_detach(struct dma_buf *dmabuf,
>  				struct dma_buf_attachment *dmabuf_attach);
>  
> -struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops,
> -			       size_t size, int flags, const char *,
> -			       struct reservation_object *);
> -
> -#define dma_buf_export(priv, ops, size, flags, resv)	\
> -	dma_buf_export_named(priv, ops, size, flags, KBUILD_MODNAME, resv)
> +struct dma_buf *dma_buf_export(struct dma_buf_export_info *exp_info);
>  
>  int dma_buf_fd(struct dma_buf *dmabuf, int flags);
>  struct dma_buf *dma_buf_get(int fd);