linux-kernel - Re: [PATCH 8/9] xen/gntdev.c: Convert to use vm_insert

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Date:   Mon, 14 Jan 2019 18:27:53 -0500
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Souptick Joarder <jrdr.linux@...il.com>, akpm@...ux-foundation.org,
        willy@...radead.org, mhocko@...e.com, jgross@...e.com,
        linux@...linux.org.uk, robin.murphy@....com
Cc:     xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH 8/9] xen/gntdev.c: Convert to use vm_insert_range

On 1/11/19 10:12 AM, Souptick Joarder wrote:
> Convert to use vm_insert_range() to map range of kernel
> memory to user vma.
>
> Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>

(although it would be good to mention in the commit that you are also
replacing count with vma_pages(vma), and why)


> ---
>  drivers/xen/gntdev.c | 16 ++++++----------
>  1 file changed, 6 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index b0b02a5..ca4acee 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -1082,18 +1082,17 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
>  {
>  	struct gntdev_priv *priv = flip->private_data;
>  	int index = vma->vm_pgoff;
> -	int count = vma_pages(vma);
>  	struct gntdev_grant_map *map;
> -	int i, err = -EINVAL;
> +	int err = -EINVAL;
>  
>  	if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
>  		return -EINVAL;
>  
>  	pr_debug("map %d+%d at %lx (pgoff %lx)\n",
> -			index, count, vma->vm_start, vma->vm_pgoff);
> +			index, vma_pages(vma), vma->vm_start, vma->vm_pgoff);
>  
>  	mutex_lock(&priv->lock);
> -	map = gntdev_find_map_index(priv, index, count);
> +	map = gntdev_find_map_index(priv, index, vma_pages(vma));
>  	if (!map)
>  		goto unlock_out;
>  	if (use_ptemod && map->vma)
> @@ -1145,12 +1144,9 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
>  		goto out_put_map;
>  
>  	if (!use_ptemod) {
> -		for (i = 0; i < count; i++) {
> -			err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
> -				map->pages[i]);
> -			if (err)
> -				goto out_put_map;
> -		}
> +		err = vm_insert_range(vma, map->pages, map->count);
> +		if (err)
> +			goto out_put_map;
>  	} else {
>  #ifdef CONFIG_X86
>  		/*