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authorColin Cross <ccross@android.com>2013-12-20 16:43:50 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-07 14:21:09 -0800
commitfee0c54e28f6ca187add93dfca226a8093cfa931 (patch)
treed62c8c58d90fda69cf035b36c457a8ce9df945ca /drivers
parent38dbfb59d1175ef458d006556061adeaa8751b72 (diff)
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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: Colin Cross <ccross@android.com> Reviewed-by: Rob Clark <robdclark@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/base/dma-buf.c18
-rw-r--r--drivers/gpu/drm/drm_prime.c2
-rw-r--r--drivers/gpu/drm/exynos/exynos_drm_dmabuf.c2
-rw-r--r--drivers/media/v4l2-core/videobuf2-dma-contig.c2
4 files changed, 14 insertions, 10 deletions
diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index 1e16cbd61da2..cfe1d8bc7bb8 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -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;
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 56805c39c906..bb516fdd195d 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -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;
}
diff --git a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
index 59827cc5e770..c786cd4f457b 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
@@ -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;
}
diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c
index 33d3871d1e13..880be0782dd9 100644
--- a/drivers/media/v4l2-core/videobuf2-dma-contig.c
+++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c
@@ -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;
}