Hi Tomasz,
Thanks for the patch.
On Tuesday 02 October 2012 16:27:33 Tomasz Stanislawski wrote:
> From: Marek Szyprowski <m.szyprowski at samsung.com>
>
> The DMA transfer must be aligned to a specific value. If userptr is not
> aligned to DMA requirements then unexpected corruptions of the memory may
> occur before or after a buffer. To prevent such situations, all unligned
> userptr buffers are rejected at VIDIOC_QBUF.
>
> Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
> ---
> drivers/media/video/videobuf2-dma-contig.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/media/video/videobuf2-dma-contig.c
> b/drivers/media/video/videobuf2-dma-contig.c index b4d287a..55f8c80 100644
> --- a/drivers/media/video/videobuf2-dma-contig.c
> +++ b/drivers/media/video/videobuf2-dma-contig.c
> @@ -494,6 +494,13 @@ static void *vb2_dc_get_userptr(void *alloc_ctx,
> unsigned long vaddr, struct vm_area_struct *vma;
> struct sg_table *sgt;
> unsigned long contig_size;
> + unsigned long dma_align = dma_get_cache_alignment();
> +
> + /* Only cache aligned DMA transfers are reliable */
> + if (!IS_ALIGNED(vaddr | size, dma_align)) {
> + pr_err("user data must be aligned to %lu bytes\n", dma_align);
> + return ERR_PTR(-EINVAL);
Do you think EFAULT would be more descriptive ? EINVAL is already used quite
extensively. We could then possibly turn pr_err() into pr_dbg() to avoid
flooding the kernel log.
> + }
>
> buf = kzalloc(sizeof *buf, GFP_KERNEL);
> if (!buf)
--
Regards,
Laurent Pinchart
