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>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c
index 33d3871d1e1..880be0782dd 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;
 	}