Re: [PATCH 16/26] mm: Provide get_user_pages_unlocked()

[KOSAKI Motohiro]

(10/2/13 10:27 AM), Jan Kara wrote:
> Provide a wrapper for get_user_pages() which takes care of acquiring and
> releasing mmap_sem. Using this function reduces amount of places in
> which we deal with mmap_sem.
> 
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
>   include/linux/mm.h | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 8b6e55ee8855..70031ead06a5 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1031,6 +1031,20 @@ long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
>   		    struct vm_area_struct **vmas);
>   int get_user_pages_fast(unsigned long start, int nr_pages, int write,
>   			struct page **pages);
> +static inline long
> +get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
> +		 	unsigned long start, unsigned long nr_pages,
> +			int write, int force, struct page **pages)
> +{
> +	long ret;
> +
> +	down_read(&mm->mmap_sem);
> +	ret = get_user_pages(tsk, mm, start, nr_pages, write, force, pages,
> +			     NULL);
> +	up_read(&mm->mmap_sem);
> +	return ret;
> +}

Hmmm. I like the idea, but I really dislike this name. I don't like xx_unlocked 
function takes a lock. It is a source of confusing, I believe. 







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