Hi Tomasz,

Thanks for the patch.

On Wednesday 23 May 2012 15:07:34 Tomasz Stanislawski wrote:
> This patch makes use of sg_alloc_table_from_pages to simplify
> handling of sg tables.

Would you mind moving this patch before 04/12, to avoid introducing a 
vb2_dc_pages_to_sgt() user only to remove it in this patch ? Otherwise this 
looks good.

> Signed-off-by: Tomasz Stanislawski <t.stanisl...@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.p...@samsung.com>
> ---
>  drivers/media/video/videobuf2-dma-contig.c |   90 +++++++------------------
>  1 file changed, 25 insertions(+), 65 deletions(-)
> 
> diff --git a/drivers/media/video/videobuf2-dma-contig.c
> b/drivers/media/video/videobuf2-dma-contig.c index 59ee81c..b5caf1d 100644
> --- a/drivers/media/video/videobuf2-dma-contig.c
> +++ b/drivers/media/video/videobuf2-dma-contig.c
> @@ -32,7 +32,7 @@ struct vb2_dc_buf {
>       /* MMAP related */
>       struct vb2_vmarea_handler       handler;
>       atomic_t                        refcount;
> -     struct sg_table                 *sgt_base;
> +     struct sg_table                 sgt_base;
> 
>       /* USERPTR related */
>       struct vm_area_struct           *vma;
> @@ -45,57 +45,6 @@ struct vb2_dc_buf {
>  /*        scatterlist table functions        */
>  /*********************************************/
> 
> -static struct sg_table *vb2_dc_pages_to_sgt(struct page **pages,
> -     unsigned int n_pages, unsigned long offset, unsigned long size)
> -{
> -     struct sg_table *sgt;
> -     unsigned int chunks;
> -     unsigned int i;
> -     unsigned int cur_page;
> -     int ret;
> -     struct scatterlist *s;
> -
> -     sgt = kzalloc(sizeof *sgt, GFP_KERNEL);
> -     if (!sgt)
> -             return ERR_PTR(-ENOMEM);
> -
> -     /* compute number of chunks */
> -     chunks = 1;
> -     for (i = 1; i < n_pages; ++i)
> -             if (pages[i] != pages[i - 1] + 1)
> -                     ++chunks;
> -
> -     ret = sg_alloc_table(sgt, chunks, GFP_KERNEL);
> -     if (ret) {
> -             kfree(sgt);
> -             return ERR_PTR(-ENOMEM);
> -     }
> -
> -     /* merging chunks and putting them into the scatterlist */
> -     cur_page = 0;
> -     for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
> -             unsigned long chunk_size;
> -             unsigned int j;
> -
> -             for (j = cur_page + 1; j < n_pages; ++j)
> -                     if (pages[j] != pages[j - 1] + 1)
> -                             break;
> -
> -             chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
> -             sg_set_page(s, pages[cur_page], min(size, chunk_size), offset);
> -             size -= chunk_size;
> -             offset = 0;
> -             cur_page = j;
> -     }
> -
> -     return sgt;
> -}
> -
> -static void vb2_dc_release_sgtable(struct sg_table *sgt)
> -{
> -     sg_free_table(sgt);
> -     kfree(sgt);
> -}
> 
>  static void vb2_dc_sgt_foreach_page(struct sg_table *sgt,
>       void (*cb)(struct page *pg))
> @@ -190,7 +139,7 @@ static void vb2_dc_put(void *buf_priv)
>       if (!atomic_dec_and_test(&buf->refcount))
>               return;
> 
> -     vb2_dc_release_sgtable(buf->sgt_base);
> +     sg_free_table(&buf->sgt_base);
>       dma_free_coherent(buf->dev, buf->size, buf->vaddr, buf->dma_addr);
>       kfree(buf);
>  }
> @@ -254,9 +203,9 @@ static void *vb2_dc_alloc(void *alloc_ctx, unsigned long
> size) 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);
> +     ret = sg_alloc_table_from_pages(&buf->sgt_base,
> +             pages, n_pages, 0, size, GFP_KERNEL);
> +     if (ret) {
>               dev_err(dev, "failed to prepare sg table\n");
>               goto fail_pages;
>       }
> @@ -379,13 +328,13 @@ static struct sg_table *vb2_dc_dmabuf_ops_map(
>       attach->dir = dir;
> 
>       /* copying the buf->base_sgt to attachment */
> -     ret = sg_alloc_table(sgt, buf->sgt_base->orig_nents, GFP_KERNEL);
> +     ret = sg_alloc_table(sgt, buf->sgt_base.orig_nents, GFP_KERNEL);
>       if (ret) {
>               kfree(attach);
>               return ERR_PTR(-ENOMEM);
>       }
> 
> -     rd = buf->sgt_base->sgl;
> +     rd = buf->sgt_base.sgl;
>       wr = sgt->sgl;
>       for (i = 0; i < sgt->orig_nents; ++i) {
>               sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
> @@ -519,7 +468,8 @@ static void vb2_dc_put_userptr(void *buf_priv)
>       if (!vma_is_io(buf->vma))
>               vb2_dc_sgt_foreach_page(sgt, vb2_dc_put_dirty_page);
> 
> -     vb2_dc_release_sgtable(sgt);
> +     sg_free_table(sgt);
> +     kfree(sgt);
>       vb2_put_vma(buf->vma);
>       kfree(buf);
>  }
> @@ -586,13 +536,20 @@ static void *vb2_dc_get_userptr(void *alloc_ctx,
> unsigned long vaddr, goto fail_vma;
>       }
> 
> -     sgt = vb2_dc_pages_to_sgt(pages, n_pages, offset, size);
> -     if (IS_ERR(sgt)) {
> -             printk(KERN_ERR "failed to create scatterlist table\n");
> +     sgt = kzalloc(sizeof *sgt, GFP_KERNEL);
> +     if (!sgt) {
> +             printk(KERN_ERR "failed to allocate sg table\n");
>               ret = -ENOMEM;
>               goto fail_get_user_pages;
>       }
> 
> +     ret = sg_alloc_table_from_pages(sgt, pages, n_pages,
> +             offset, size, GFP_KERNEL);
> +     if (ret) {
> +             printk(KERN_ERR "failed to initialize sg table\n");
> +             goto fail_sgt;
> +     }
> +
>       /* pages are no longer needed */
>       kfree(pages);
>       pages = NULL;
> @@ -602,7 +559,7 @@ static void *vb2_dc_get_userptr(void *alloc_ctx,
> unsigned long vaddr, if (sgt->nents <= 0) {
>               printk(KERN_ERR "failed to map scatterlist\n");
>               ret = -EIO;
> -             goto fail_sgt;
> +             goto fail_sgt_init;
>       }
> 
>       contig_size = vb2_dc_get_contiguous_size(sgt);
> @@ -622,10 +579,13 @@ static void *vb2_dc_get_userptr(void *alloc_ctx,
> unsigned long vaddr, fail_map_sg:
>       dma_unmap_sg(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
> 
> -fail_sgt:
> +fail_sgt_init:
>       if (!vma_is_io(buf->vma))
>               vb2_dc_sgt_foreach_page(sgt, put_page);
> -     vb2_dc_release_sgtable(sgt);
> +     sg_free_table(sgt);
> +
> +fail_sgt:
> +     kfree(sgt);
> 
>  fail_get_user_pages:
>       if (pages && !vma_is_io(buf->vma))
-- 
Regards,

Laurent Pinchart

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