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Commit fee0c54e authored by Colin Cross's avatar Colin Cross Committed by Greg Kroah-Hartman
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dma-buf: avoid using IS_ERR_OR_NULL 



dma_buf_map_attachment and dma_buf_vmap can return NULL or
ERR_PTR on a error.  This encourages a common buggy pattern in
callers:
	sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
	if (IS_ERR_OR_NULL(sgt))
                return PTR_ERR(sgt);

This causes the caller to return 0 on an error.  IS_ERR_OR_NULL
is almost always a sign of poorly-defined error handling.

This patch converts dma_buf_map_attachment to always return
ERR_PTR, and fixes the callers that incorrectly handled NULL.
There are a few more callers that were not checking for NULL
at all, which would have dereferenced a NULL pointer later.
There are also a few more callers that correctly handled NULL
and ERR_PTR differently, I left those alone but they could also
be modified to delete the NULL check.

This patch also converts dma_buf_vmap to always return NULL.
All the callers to dma_buf_vmap only check for NULL, and would
have dereferenced an ERR_PTR and panic'd if one was ever
returned. This is not consistent with the rest of the dma buf
APIs, but matches the expectations of all of the callers.

Signed-off-by: default avatarColin Cross <ccross@android.com>
Reviewed-by: default avatarRob Clark <robdclark@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 38dbfb59

drivers/base/dma-buf.c

+11 −7
Original line number Diff line number Diff line
@@ -251,9 +251,8 @@ EXPORT_SYMBOL_GPL(dma_buf_put); 
 * @dmabuf:	[in]	buffer to attach device to.

 * @dev:	[in]	device to be attached.

 *

 * Returns struct dma_buf_attachment * for this attachment; may return negative

 * error codes.

 *

 * Returns struct dma_buf_attachment * for this attachment; returns ERR_PTR on

 * error.

 */

struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,

					  struct device *dev)
@@ -319,9 +318,8 @@ EXPORT_SYMBOL_GPL(dma_buf_detach); 
 * @attach:	[in]	attachment whose scatterlist is to be returned

 * @direction:	[in]	direction of DMA transfer

 *

 * Returns sg_table containing the scatterlist to be returned; may return NULL

 * or ERR_PTR.

 *

 * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR

 * on error.

 */

struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,

					enum dma_data_direction direction)
@@ -334,6 +332,8 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, 
		return ERR_PTR(-EINVAL);



	sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);

	if (!sg_table)

		sg_table = ERR_PTR(-ENOMEM);



	return sg_table;

}
@@ -544,6 +544,8 @@ EXPORT_SYMBOL_GPL(dma_buf_mmap); 
 * These calls are optional in drivers. The intended use for them

 * is for mapping objects linear in kernel space for high use objects.

 * Please attempt to use kmap/kunmap before thinking about these interfaces.

 *

 * Returns NULL on error.

 */

void *dma_buf_vmap(struct dma_buf *dmabuf)

{
@@ -566,7 +568,9 @@ void *dma_buf_vmap(struct dma_buf *dmabuf) 
	BUG_ON(dmabuf->vmap_ptr);



	ptr = dmabuf->ops->vmap(dmabuf);

	if (IS_ERR_OR_NULL(ptr))

	if (WARN_ON_ONCE(IS_ERR(ptr)))

		ptr = NULL;

	if (!ptr)

		goto out_unlock;



	dmabuf->vmap_ptr = ptr;

drivers/gpu/drm/drm_prime.c

+1 −1
Original line number Diff line number Diff line
@@ -471,7 +471,7 @@ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev, 
	get_dma_buf(dma_buf);



	sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);

	if (IS_ERR_OR_NULL(sgt)) {

	if (IS_ERR(sgt)) {

		ret = PTR_ERR(sgt);

		goto fail_detach;

	}

drivers/gpu/drm/exynos/exynos_drm_dmabuf.c

+1 −1
Original line number Diff line number Diff line
@@ -224,7 +224,7 @@ struct drm_gem_object *exynos_dmabuf_prime_import(struct drm_device *drm_dev, 
	get_dma_buf(dma_buf);



	sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);

	if (IS_ERR_OR_NULL(sgt)) {

	if (IS_ERR(sgt)) {

		ret = PTR_ERR(sgt);

		goto err_buf_detach;

	}

drivers/media/v4l2-core/videobuf2-dma-contig.c

+1 −1
Original line number Diff line number Diff line
@@ -719,7 +719,7 @@ static int vb2_dc_map_dmabuf(void *mem_priv) 


	/* get the associated scatterlist for this buffer */

	sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);

	if (IS_ERR_OR_NULL(sgt)) {

	if (IS_ERR(sgt)) {

		pr_err("Error getting dmabuf scatterlist\n");

		return -EINVAL;

	}