[PATCH] media: videobuf2: check constants during build time

[PATCH] media: videobuf2: check constants during build time

[Michał Mirosław]

There is nothing a driver author can do fix in the driver to make the
global constants match. Since the assertion can be verified at build
time, don't return EINVAL at runtime for it.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
---
 drivers/media/common/videobuf2/videobuf2-v4l2.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 9201d854dbcc..1cd26faee503 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -903,6 +903,11 @@ EXPORT_SYMBOL_GPL(vb2_expbuf);
 
 int vb2_queue_init_name(struct vb2_queue *q, const char *name)
 {
+	/* vb2_memory should match with v4l2_memory */
+	BUILD_BUG_ON(VB2_MEMORY_MMAP != (int)V4L2_MEMORY_MMAP);
+	BUILD_BUG_ON(VB2_MEMORY_USERPTR != (int)V4L2_MEMORY_USERPTR);
+	BUILD_BUG_ON(VB2_MEMORY_DMABUF != (int)V4L2_MEMORY_DMABUF);
+
 	/*
 	 * Sanity check
 	 */
@@ -916,12 +921,6 @@ int vb2_queue_init_name(struct vb2_queue *q, const char *name)
 	WARN_ON((q->timestamp_flags & V4L2_BUF_FLAG_TIMESTAMP_MASK) ==
 		V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN);
 
-	/* Warn that vb2_memory should match with v4l2_memory */
-	if (WARN_ON(VB2_MEMORY_MMAP != (int)V4L2_MEMORY_MMAP)
-		|| WARN_ON(VB2_MEMORY_USERPTR != (int)V4L2_MEMORY_USERPTR)
-		|| WARN_ON(VB2_MEMORY_DMABUF != (int)V4L2_MEMORY_DMABUF))
-		return -EINVAL;
-
 	if (q->buf_struct_size == 0)
 		q->buf_struct_size = sizeof(struct vb2_v4l2_buffer);
 
-- 
2.39.5

Re: [PATCH] media: videobuf2: check constants during build time

[Marek Szyprowski]

On 28.03.2025 23:05, Michał Mirosław wrote:
> There is nothing a driver author can do fix in the driver to make the
> global constants match. Since the assertion can be verified at build
> time, don't return EINVAL at runtime for it.
>
> Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
>   drivers/media/common/videobuf2/videobuf2-v4l2.c | 11 +++++------
>   1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> index 9201d854dbcc..1cd26faee503 100644
> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> @@ -903,6 +903,11 @@ EXPORT_SYMBOL_GPL(vb2_expbuf);
>   
>   int vb2_queue_init_name(struct vb2_queue *q, const char *name)
>   {
> +	/* vb2_memory should match with v4l2_memory */
> +	BUILD_BUG_ON(VB2_MEMORY_MMAP != (int)V4L2_MEMORY_MMAP);
> +	BUILD_BUG_ON(VB2_MEMORY_USERPTR != (int)V4L2_MEMORY_USERPTR);
> +	BUILD_BUG_ON(VB2_MEMORY_DMABUF != (int)V4L2_MEMORY_DMABUF);
> +
>   	/*
>   	 * Sanity check
>   	 */
> @@ -916,12 +921,6 @@ int vb2_queue_init_name(struct vb2_queue *q, const char *name)
>   	WARN_ON((q->timestamp_flags & V4L2_BUF_FLAG_TIMESTAMP_MASK) ==
>   		V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN);
>   
> -	/* Warn that vb2_memory should match with v4l2_memory */
> -	if (WARN_ON(VB2_MEMORY_MMAP != (int)V4L2_MEMORY_MMAP)
> -		|| WARN_ON(VB2_MEMORY_USERPTR != (int)V4L2_MEMORY_USERPTR)
> -		|| WARN_ON(VB2_MEMORY_DMABUF != (int)V4L2_MEMORY_DMABUF))
> -		return -EINVAL;
> -
>   	if (q->buf_struct_size == 0)
>   		q->buf_struct_size = sizeof(struct vb2_v4l2_buffer);
>   

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland