Hi Tomasz,
Thanks for the patch.
On Wednesday 23 May 2012 15:07:27 Tomasz Stanislawski wrote:
> This patch adds the setup of sglist list for MMAP buffers.
> It is needed for buffer exporting via DMABUF mechanism.
>
> Signed-off-by: Tomasz Stanislawski <t.stanislaws@xxxxxxxxxxx>
> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> ---
> drivers/media/video/videobuf2-dma-contig.c | 70 ++++++++++++++++++++++++-
> 1 file changed, 68 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/video/videobuf2-dma-contig.c
> b/drivers/media/video/videobuf2-dma-contig.c index 52b4f59..ae656be 100644
> --- a/drivers/media/video/videobuf2-dma-contig.c
> +++ b/drivers/media/video/videobuf2-dma-contig.c
> @@ -32,6 +32,7 @@ struct vb2_dc_buf {
> /* MMAP related */
> struct vb2_vmarea_handler handler;
> atomic_t refcount;
> + struct sg_table *sgt_base;
>
> /* USERPTR related */
> struct vm_area_struct *vma;
> @@ -189,14 +190,37 @@ static void vb2_dc_put(void *buf_priv)
> if (!atomic_dec_and_test(&buf->refcount))
> return;
>
> + vb2_dc_release_sgtable(buf->sgt_base);
> dma_free_coherent(buf->dev, buf->size, buf->vaddr, buf->dma_addr);
> kfree(buf);
> }
>
> +static int vb2_dc_kaddr_to_pages(unsigned long kaddr,
> + struct page **pages, unsigned int n_pages)
> +{
> + unsigned int i;
> + unsigned long pfn;
> + struct vm_area_struct vma = {
> + .vm_flags = VM_IO | VM_PFNMAP,
> + .vm_mm = current->mm,
> + };
> +
> + for (i = 0; i < n_pages; ++i, kaddr += PAGE_SIZE) {
The follow_pfn() kerneldoc mentions that it looks up a PFN for a user address.
The only users I've found in the kernel sources pass a user address. Is it
legal to use it for kernel addresses ?
> + if (follow_pfn(&vma, kaddr, &pfn))
> + break;
> + pages[i] = pfn_to_page(pfn);
> + }
> +
> + return i;
> +}
> +
> static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size)
> {
> struct device *dev = alloc_ctx;
> struct vb2_dc_buf *buf;
> + int ret = -ENOMEM;
> + int n_pages;
> + struct page **pages = NULL;
>
> buf = kzalloc(sizeof *buf, GFP_KERNEL);
> if (!buf)
> @@ -205,10 +229,41 @@ static void *vb2_dc_alloc(void *alloc_ctx, unsigned
> long size) buf->vaddr = dma_alloc_coherent(dev, size, &buf->dma_addr,
> GFP_KERNEL); if (!buf->vaddr) {
> dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size);
> - kfree(buf);
> - return ERR_PTR(-ENOMEM);
> + goto fail_buf;
> + }
> +
> + WARN_ON((unsigned long)buf->vaddr & ~PAGE_MASK);
> + WARN_ON(buf->dma_addr & ~PAGE_MASK);
> +
> + n_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
> +
> + pages = kmalloc(n_pages * sizeof pages[0], GFP_KERNEL);
> + if (!pages) {
> + dev_err(dev, "failed to alloc page table\n");
> + goto fail_dma;
> + }
> +
> + ret = vb2_dc_kaddr_to_pages((unsigned long)buf->vaddr, pages, n_pages);
> + if (ret < 0) {
> + dev_err(dev, "failed to get buffer pages from DMA API\n");
> + goto fail_pages;
> + }
> + if (ret != n_pages) {
> + ret = -EFAULT;
> + dev_err(dev, "failed to get all pages from DMA API\n");
> + goto fail_pages;
> + }
> +
> + buf->sgt_base = vb2_dc_pages_to_sgt(pages, n_pages, 0, size);
> + if (IS_ERR(buf->sgt_base)) {
> + ret = PTR_ERR(buf->sgt_base);
> + dev_err(dev, "failed to prepare sg table\n");
> + goto fail_pages;
> }
>
> + /* pages are no longer needed */
> + kfree(pages);
> +
> buf->dev = dev;
> buf->size = size;
>
> @@ -219,6 +274,17 @@ static void *vb2_dc_alloc(void *alloc_ctx, unsigned
> long size) atomic_inc(&buf->refcount);
>
> return buf;
> +
> +fail_pages:
> + kfree(pages);
> +
> +fail_dma:
You can merge the fail_pages and fail_dma labels, as kfree(NULL) is valid.
> + dma_free_coherent(dev, size, buf->vaddr, buf->dma_addr);
> +
> +fail_buf:
> + kfree(buf);
> +
> + return ERR_PTR(ret);
> }
>
> static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
--
Regards,
Laurent Pinchart
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