linux-kernel - Re: [PATCH 4/6] char: use vma_pages() to replace (vm_end

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Message-ID: <516C9F00.9020009@huawei.com>
Date:	Tue, 16 Apr 2013 08:44:48 +0800
From:	Xie XiuQi <xiexiuqi@...wei.com>
To:	Libin <huawei.libin@...wei.com>
CC:	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	David Airlie <airlied@...ux.ie>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"Hans J. Koch" <hjk@...sjkoch.de>,
	Petr Vandrovec <petr@...drovec.name>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Konstantin Khlebnikov <khlebnikov@...nvz.org>,
	Thomas Hellstrom <thellstrom@...are.com>,
	Dave Airlie <airlied@...hat.com>,
	Nadia Yvette Chambers <nyc@...omorphy.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Al Viro <viro@...iv.linux.org.uk>,
	Mel Gorman <mgorman@...e.de>, Hugh Dickins <hughd@...gle.com>,
	Rik van Riel <riel@...hat.com>,
	David Rientjes <rientjes@...gle.com>,
	Michel Lespinasse <walken@...gle.com>,
	<linux-kernel@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
	<linux-pci@...r.kernel.org>, <linux-mm@...ck.org>,
	<guohanjun@...wei.com>, <wangyijing@...wei.com>
Subject: Re: [PATCH 4/6] char: use vma_pages() to replace (vm_end - vm_start)
 >> PAGE_SHIFT

On 2013/4/15 20:48, Libin wrote:
> (*->vm_end - *->vm_start) >> PAGE_SHIFT operation is implemented
> as a inline funcion vma_pages() in linux/mm.h, so using it.
> 
> Signed-off-by: Libin <huawei.libin@...wei.com>
> ---
>  drivers/char/mspec.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/char/mspec.c b/drivers/char/mspec.c
> index e1f60f9..ed0703f 100644
> --- a/drivers/char/mspec.c
> +++ b/drivers/char/mspec.c
> @@ -168,7 +168,7 @@ mspec_close(struct vm_area_struct *vma)
>  	if (!atomic_dec_and_test(&vdata->refcnt))
>  		return;
>  
> -	last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
> +	last_index = vma_pages(vdata);
>  	for (index = 0; index < last_index; index++) {
>  		if (vdata->maddr[index] == 0)
>  			continue;
> 

This function mspec_mmap also need modification...
And you can change int to unsigned long.

static int
mspec_mmap(struct file *file, struct vm_area_struct *vma,
					enum mspec_page_type type)
{
	struct vma_data *vdata;
	int pages, vdata_size, flags = 0;

	if (vma->vm_pgoff != 0)
		return -EINVAL;

	if ((vma->vm_flags & VM_SHARED) == 0)
		return -EINVAL;

	if ((vma->vm_flags & VM_WRITE) == 0)
		return -EPERM;

	pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
	vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
	if (vdata_size <= PAGE_SIZE)
		vdata = kzalloc(vdata_size, GFP_KERNEL);
	else {
		vdata = vzalloc(vdata_size);
		flags = VMD_VMALLOCED;
	}
	if (!vdata)
		return -ENOMEM;


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