| Message ID | 1349188056-4886-23-git-send-email-t.stanislaws@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Tomasz, Thanks for the patch. On Tuesday 02 October 2012 16:27:33 Tomasz Stanislawski wrote: > From: Marek Szyprowski <m.szyprowski@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@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)
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); + } buf = kzalloc(sizeof *buf, GFP_KERNEL); if (!buf)