v4l2: change kmalloc to vmalloc for sglist allocation in videobuf_dma_map/unmap

  From: Cohen David.A (Nokia-D/Helsinki) <david.cohen@nokia.com>

Change kmalloc()/kfree() to vmalloc()/vfree() for sglist allocation
during videobuf_dma_map() and videobuf_dma_unmap()

High resolution sensors might require too many contiguous pages
to be allocated for sglist by kmalloc() during videobuf_dma_map()
(i.e. 256Kib for 8MP sensor).
In such situations, kmalloc() could face some problem to find the
required free memory. vmalloc() is a safer solution instead, as the
allocated memory does not need to be contiguous.

Signed-off-by: David Cohen <david.cohen@nokia.com>
---
 drivers/media/video/videobuf-dma-sg.c |   17 +++++++++--------
 1 files changed, 9 insertions(+), 8 deletions(-)
  

On Thu, May 14, 2009 at 09:04:48AM +0200, Cohen David.A (Nokia-D/Helsinki) wrote:
> From: Cohen David.A (Nokia-D/Helsinki) <david.cohen@nokia.com>
> 
> Change kmalloc()/kfree() to vmalloc()/vfree() for sglist allocation
> during videobuf_dma_map() and videobuf_dma_unmap()
> 
> High resolution sensors might require too many contiguous pages
> to be allocated for sglist by kmalloc() during videobuf_dma_map()
> (i.e. 256Kib for 8MP sensor).
> In such situations, kmalloc() could face some problem to find the
> required free memory. vmalloc() is a safer solution instead, as the
> allocated memory does not need to be contiguous.
> 
> Signed-off-by: David Cohen <david.cohen@nokia.com>
> ---
>  drivers/media/video/videobuf-dma-sg.c |   17 +++++++++--------
>  1 files changed, 9 insertions(+), 8 deletions(-)

Hi Mauro,

Any comments?

Br,

David Cohen

> 
> diff --git a/drivers/media/video/videobuf-dma-sg.c b/drivers/media/video/videobuf-dma-sg.c
> index da1790e..c9a5d7e 100644
> --- a/drivers/media/video/videobuf-dma-sg.c
> +++ b/drivers/media/video/videobuf-dma-sg.c
> @@ -58,9 +58,10 @@ videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages)
>  	struct page *pg;
>  	int i;
>  
> -	sglist = kcalloc(nr_pages, sizeof(struct scatterlist), GFP_KERNEL);
> +	sglist = vmalloc(nr_pages * sizeof(*sglist));
>  	if (NULL == sglist)
>  		return NULL;
> +	memset(sglist, 0, nr_pages * sizeof(*sglist));
>  	sg_init_table(sglist, nr_pages);
>  	for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
>  		pg = vmalloc_to_page(virt);
> @@ -72,7 +73,7 @@ videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages)
>  	return sglist;
>  
>   err:
> -	kfree(sglist);
> +	vfree(sglist);
>  	return NULL;
>  }
>  
> @@ -84,7 +85,7 @@ videobuf_pages_to_sg(struct page **pages, int nr_pages, int offset)
>  
>  	if (NULL == pages[0])
>  		return NULL;
> -	sglist = kmalloc(nr_pages * sizeof(*sglist), GFP_KERNEL);
> +	sglist = vmalloc(nr_pages * sizeof(*sglist));
>  	if (NULL == sglist)
>  		return NULL;
>  	sg_init_table(sglist, nr_pages);
> @@ -104,12 +105,12 @@ videobuf_pages_to_sg(struct page **pages, int nr_pages, int offset)
>  
>   nopage:
>  	dprintk(2,"sgl: oops - no page\n");
> -	kfree(sglist);
> +	vfree(sglist);
>  	return NULL;
>  
>   highmem:
>  	dprintk(2,"sgl: oops - highmem page\n");
> -	kfree(sglist);
> +	vfree(sglist);
>  	return NULL;
>  }
>  
> @@ -230,7 +231,7 @@ int videobuf_dma_map(struct videobuf_queue* q, struct videobuf_dmabuf *dma)
>  						(dma->vmalloc,dma->nr_pages);
>  	}
>  	if (dma->bus_addr) {
> -		dma->sglist = kmalloc(sizeof(struct scatterlist), GFP_KERNEL);
> +		dma->sglist = vmalloc(sizeof(*dma->sglist));
>  		if (NULL != dma->sglist) {
>  			dma->sglen  = 1;
>  			sg_dma_address(&dma->sglist[0]) = dma->bus_addr & PAGE_MASK;
> @@ -248,7 +249,7 @@ int videobuf_dma_map(struct videobuf_queue* q, struct videobuf_dmabuf *dma)
>  		if (0 == dma->sglen) {
>  			printk(KERN_WARNING
>  			       "%s: videobuf_map_sg failed\n",__func__);
> -			kfree(dma->sglist);
> +			vfree(dma->sglist);
>  			dma->sglist = NULL;
>  			dma->sglen = 0;
>  			return -EIO;
> @@ -274,7 +275,7 @@ int videobuf_dma_unmap(struct videobuf_queue* q,struct videobuf_dmabuf *dma)
>  
>  	dma_unmap_sg(q->dev, dma->sglist, dma->nr_pages, dma->direction);
>  
> -	kfree(dma->sglist);
> +	vfree(dma->sglist);
>  	dma->sglist = NULL;
>  	dma->sglen = 0;
>  	return 0;
> -- 
> 1.6.1
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