This patch makes use of sg_alloc_table_from_pages to simplify
handling of sg tables.

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))
-- 
1.7.9.5

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