forked from Minki/linux
[media] v4l: vb2-dma-contig: add support for scatterlist in userptr mode
This patch introduces usage of dma_map_sg to map memory behind a userspace pointer to a device as dma-contiguous mapping. This patch contains some of the code kindly provided by Marek Szyprowski <m.szyprowski@samsung.com> and Kamil Debski <k.debski@samsung.com> and Andrzej Pietrasiewicz <andrzej.p@samsung.com>. Kind thanks for bug reports from Laurent Pinchart <laurent.pinchart@ideasonboard.com> and Seung-Woo Kim <sw0312.kim@samsung.com>. Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Tomasz Stanislawski
Mauro Carvalho Chehab
parent
40d8b7669b
commit
e15dab752d
@ -11,6 +11,8 @@
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*/
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#include <linux/module.h>
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#include <linux/scatterlist.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/dma-mapping.h>
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@ -27,6 +29,8 @@ struct vb2_dc_buf {
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void *vaddr;
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unsigned long size;
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dma_addr_t dma_addr;
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enum dma_data_direction dma_dir;
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struct sg_table *dma_sgt;
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/* MMAP related */
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struct vb2_vmarea_handler handler;
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@ -36,6 +40,44 @@ struct vb2_dc_buf {
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struct vm_area_struct *vma;
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};
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/*********************************************/
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/* scatterlist table functions */
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/*********************************************/
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static void vb2_dc_sgt_foreach_page(struct sg_table *sgt,
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void (*cb)(struct page *pg))
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{
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struct scatterlist *s;
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unsigned int i;
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for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
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struct page *page = sg_page(s);
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unsigned int n_pages = PAGE_ALIGN(s->offset + s->length)
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>> PAGE_SHIFT;
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unsigned int j;
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for (j = 0; j < n_pages; ++j, ++page)
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cb(page);
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}
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}
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static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt)
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{
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struct scatterlist *s;
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dma_addr_t expected = sg_dma_address(sgt->sgl);
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unsigned int i;
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unsigned long size = 0;
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for_each_sg(sgt->sgl, s, sgt->nents, i) {
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if (sg_dma_address(s) != expected)
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break;
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expected = sg_dma_address(s) + sg_dma_len(s);
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size += sg_dma_len(s);
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}
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return size;
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}
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/*********************************************/
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/* callbacks for all buffers */
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/*********************************************/
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@ -122,42 +164,194 @@ static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
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/* callbacks for USERPTR buffers */
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/*********************************************/
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static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
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unsigned long size, int write)
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static inline int vma_is_io(struct vm_area_struct *vma)
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{
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return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
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}
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static int vb2_dc_get_user_pages(unsigned long start, struct page **pages,
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int n_pages, struct vm_area_struct *vma, int write)
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{
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if (vma_is_io(vma)) {
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unsigned int i;
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for (i = 0; i < n_pages; ++i, start += PAGE_SIZE) {
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unsigned long pfn;
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int ret = follow_pfn(vma, start, &pfn);
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if (ret) {
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pr_err("no page for address %lu\n", start);
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return ret;
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}
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pages[i] = pfn_to_page(pfn);
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}
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} else {
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int n;
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n = get_user_pages(current, current->mm, start & PAGE_MASK,
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n_pages, write, 1, pages, NULL);
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/* negative error means that no page was pinned */
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n = max(n, 0);
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if (n != n_pages) {
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pr_err("got only %d of %d user pages\n", n, n_pages);
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while (n)
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put_page(pages[--n]);
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return -EFAULT;
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}
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}
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return 0;
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}
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static void vb2_dc_put_dirty_page(struct page *page)
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{
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set_page_dirty_lock(page);
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put_page(page);
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}
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static void vb2_dc_put_userptr(void *buf_priv)
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{
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struct vb2_dc_buf *buf = buf_priv;
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struct sg_table *sgt = buf->dma_sgt;
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dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
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if (!vma_is_io(buf->vma))
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vb2_dc_sgt_foreach_page(sgt, vb2_dc_put_dirty_page);
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sg_free_table(sgt);
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kfree(sgt);
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vb2_put_vma(buf->vma);
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kfree(buf);
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}
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static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
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unsigned long size, int write)
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{
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struct vb2_dc_conf *conf = alloc_ctx;
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struct vb2_dc_buf *buf;
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unsigned long start;
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unsigned long end;
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unsigned long offset;
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struct page **pages;
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int n_pages;
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int ret = 0;
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struct vm_area_struct *vma;
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dma_addr_t dma_addr = 0;
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int ret;
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struct sg_table *sgt;
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unsigned long contig_size;
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buf = kzalloc(sizeof *buf, GFP_KERNEL);
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if (!buf)
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return ERR_PTR(-ENOMEM);
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ret = vb2_get_contig_userptr(vaddr, size, &vma, &dma_addr);
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if (ret) {
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printk(KERN_ERR "Failed acquiring VMA for vaddr 0x%08lx\n",
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vaddr);
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kfree(buf);
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return ERR_PTR(ret);
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buf->dev = conf->dev;
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buf->dma_dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
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start = vaddr & PAGE_MASK;
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offset = vaddr & ~PAGE_MASK;
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end = PAGE_ALIGN(vaddr + size);
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n_pages = (end - start) >> PAGE_SHIFT;
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pages = kmalloc(n_pages * sizeof(pages[0]), GFP_KERNEL);
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if (!pages) {
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ret = -ENOMEM;
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pr_err("failed to allocate pages table\n");
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goto fail_buf;
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}
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/* current->mm->mmap_sem is taken by videobuf2 core */
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vma = find_vma(current->mm, vaddr);
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if (!vma) {
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pr_err("no vma for address %lu\n", vaddr);
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ret = -EFAULT;
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goto fail_pages;
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}
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if (vma->vm_end < vaddr + size) {
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pr_err("vma at %lu is too small for %lu bytes\n", vaddr, size);
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ret = -EFAULT;
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goto fail_pages;
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}
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buf->vma = vb2_get_vma(vma);
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if (!buf->vma) {
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pr_err("failed to copy vma\n");
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ret = -ENOMEM;
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goto fail_pages;
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}
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/* extract page list from userspace mapping */
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ret = vb2_dc_get_user_pages(start, pages, n_pages, vma, write);
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if (ret) {
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pr_err("failed to get user pages\n");
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goto fail_vma;
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}
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sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
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if (!sgt) {
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pr_err("failed to allocate sg table\n");
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ret = -ENOMEM;
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goto fail_get_user_pages;
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}
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ret = sg_alloc_table_from_pages(sgt, pages, n_pages,
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offset, size, GFP_KERNEL);
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if (ret) {
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pr_err("failed to initialize sg table\n");
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goto fail_sgt;
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}
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/* pages are no longer needed */
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kfree(pages);
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pages = NULL;
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sgt->nents = dma_map_sg(buf->dev, sgt->sgl, sgt->orig_nents,
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buf->dma_dir);
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if (sgt->nents <= 0) {
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pr_err("failed to map scatterlist\n");
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ret = -EIO;
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goto fail_sgt_init;
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}
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contig_size = vb2_dc_get_contiguous_size(sgt);
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if (contig_size < size) {
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pr_err("contiguous mapping is too small %lu/%lu\n",
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contig_size, size);
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ret = -EFAULT;
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goto fail_map_sg;
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}
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buf->dma_addr = sg_dma_address(sgt->sgl);
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buf->size = size;
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buf->dma_addr = dma_addr;
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buf->vma = vma;
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buf->dma_sgt = sgt;
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return buf;
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}
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static void vb2_dc_put_userptr(void *mem_priv)
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{
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struct vb2_dc_buf *buf = mem_priv;
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fail_map_sg:
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dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
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if (!buf)
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return;
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fail_sgt_init:
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if (!vma_is_io(buf->vma))
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vb2_dc_sgt_foreach_page(sgt, put_page);
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sg_free_table(sgt);
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fail_sgt:
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kfree(sgt);
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fail_get_user_pages:
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if (pages && !vma_is_io(buf->vma))
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while (n_pages)
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put_page(pages[--n_pages]);
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fail_vma:
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vb2_put_vma(buf->vma);
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fail_pages:
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kfree(pages); /* kfree is NULL-proof */
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fail_buf:
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kfree(buf);
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return ERR_PTR(ret);
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}
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/*********************************************/
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