[1/2,v3] media: vb2: support userptr for PFN mappings.

  Some video devices need to use contiguous memory
which is not backed by pages as it happens with
vmalloc. This patch provides userptr handling for
those devices.

---
Changes since v2:
 - Do not grab mm->mmap_sem.

Signed-off-by: Javier Martin <javier.martin@vista-silicon.com>
---
 drivers/media/video/videobuf2-vmalloc.c |   71 +++++++++++++++++++++----------
 1 files changed, 48 insertions(+), 23 deletions(-)
  

Hi Javier,

Thanks for the patch.

On Wednesday 04 January 2012 16:46:51 Javier Martin wrote:
> Some video devices need to use contiguous memory
> which is not backed by pages as it happens with
> vmalloc. This patch provides userptr handling for
> those devices.
> 
> ---
> Changes since v2:
>  - Do not grab mm->mmap_sem.
> 
> Signed-off-by: Javier Martin <javier.martin@vista-silicon.com>
> ---
>  drivers/media/video/videobuf2-vmalloc.c |   71
> +++++++++++++++++++++---------- 1 files changed, 48 insertions(+), 23
> deletions(-)
> 
> diff --git a/drivers/media/video/videobuf2-vmalloc.c
> b/drivers/media/video/videobuf2-vmalloc.c index 03aa62f..e621db6 100644
> --- a/drivers/media/video/videobuf2-vmalloc.c
> +++ b/drivers/media/video/videobuf2-vmalloc.c
> @@ -10,6 +10,7 @@
>   * the Free Software Foundation.
>   */
> 
> +#include <linux/io.h>
>  #include <linux/module.h>
>  #include <linux/mm.h>
>  #include <linux/sched.h>
> @@ -22,6 +23,7 @@
>  struct vb2_vmalloc_buf {
>  	void				*vaddr;
>  	struct page			**pages;
> +	struct vm_area_struct		*vma;
>  	int				write;
>  	unsigned long			size;
>  	unsigned int			n_pages;
> @@ -71,6 +73,9 @@ static void *vb2_vmalloc_get_userptr(void *alloc_ctx,
> unsigned long vaddr, struct vb2_vmalloc_buf *buf;
>  	unsigned long first, last;
>  	int n_pages, offset;
> +	struct vm_area_struct *vma;
> +	struct vm_area_struct *res_vma;
> +	dma_addr_t physp;
> 
>  	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
>  	if (!buf)
> @@ -80,23 +85,37 @@ static void *vb2_vmalloc_get_userptr(void *alloc_ctx,
> unsigned long vaddr, offset = vaddr & ~PAGE_MASK;
>  	buf->size = size;
> 
> -	first = vaddr >> PAGE_SHIFT;
> -	last  = (vaddr + size - 1) >> PAGE_SHIFT;
> -	buf->n_pages = last - first + 1;
> -	buf->pages = kzalloc(buf->n_pages * sizeof(struct page *), GFP_KERNEL);
> -	if (!buf->pages)
> -		goto fail_pages_array_alloc;
> 
> -	/* current->mm->mmap_sem is taken by videobuf2 core */
> -	n_pages = get_user_pages(current, current->mm, vaddr & PAGE_MASK,
> -					buf->n_pages, write, 1, /* force */
> -					buf->pages, NULL);
> -	if (n_pages != buf->n_pages)
> -		goto fail_get_user_pages;
> -
> -	buf->vaddr = vm_map_ram(buf->pages, buf->n_pages, -1, PAGE_KERNEL);
> -	if (!buf->vaddr)
> -		goto fail_get_user_pages;
> +	vma = find_vma(current->mm, vaddr);
> +	if (vma && (vma->vm_flags & VM_PFNMAP) && (vma->vm_pgoff)) {
> +		if (vb2_get_contig_userptr(vaddr, size, &res_vma, &physp))

One small comment here. You don't use the vma variable from this point on, so 
maybe you could remove res_vma and use vma instead.

> +			goto fail_pages_array_alloc;
> +		buf->vma = res_vma;
> +		buf->vaddr = ioremap_nocache(physp, size);
> +		if (!buf->vaddr)
> +			goto fail_pages_array_alloc;
> +	} else {
> +		first = vaddr >> PAGE_SHIFT;
> +		last  = (vaddr + size - 1) >> PAGE_SHIFT;
> +		buf->n_pages = last - first + 1;
> +		buf->pages = kzalloc(buf->n_pages * sizeof(struct page *),
> +				     GFP_KERNEL);
> +		if (!buf->pages)
> +			goto fail_pages_array_alloc;
> +
> +		/* current->mm->mmap_sem is taken by videobuf2 core */
> +		n_pages = get_user_pages(current, current->mm,
> +					 vaddr & PAGE_MASK, buf->n_pages,
> +					 write, 1, /* force */
> +					 buf->pages, NULL);
> +		if (n_pages != buf->n_pages)
> +			goto fail_get_user_pages;
> +
> +		buf->vaddr = vm_map_ram(buf->pages, buf->n_pages, -1,
> +					PAGE_KERNEL);
> +		if (!buf->vaddr)
> +			goto fail_get_user_pages;
> +	}
> 
>  	buf->vaddr += offset;
>  	return buf;
> @@ -120,14 +139,20 @@ static void vb2_vmalloc_put_userptr(void *buf_priv)
>  	unsigned long vaddr = (unsigned long)buf->vaddr & PAGE_MASK;
>  	unsigned int i;
> 
> -	if (vaddr)
> -		vm_unmap_ram((void *)vaddr, buf->n_pages);
> -	for (i = 0; i < buf->n_pages; ++i) {
> -		if (buf->write)
> -			set_page_dirty_lock(buf->pages[i]);
> -		put_page(buf->pages[i]);
> +	if (buf->pages) {
> +		if (vaddr)
> +			vm_unmap_ram((void *)vaddr, buf->n_pages);
> +		for (i = 0; i < buf->n_pages; ++i) {
> +			if (buf->write)
> +				set_page_dirty_lock(buf->pages[i]);
> +			put_page(buf->pages[i]);
> +		}
> +		kfree(buf->pages);
> +	} else {
> +		if (buf->vma)
> +			vb2_put_vma(buf->vma);
> +		iounmap(buf->vaddr);
>  	}
> -	kfree(buf->pages);
>  	kfree(buf);
>  }