Re: [RFC][PATCH 2/5] pagemap: use PAGE_MASK/PAGE_ALIGN()

[Christian Ehrhardt]

In linux.kernel, you wrote:
>
> Use existing macros (PAGE_MASK/PAGE_ALIGN()) instead of
> open-coding them.
>
> Signed-off-by: Dave Hansen <haveblue@xxxxxxxxxx>
> ---
>
>  lxc-dave/fs/proc/task_mmu.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff -puN fs/proc/task_mmu.c~pagemap-use-PAGE_MASK fs/proc/task_mmu.c
> --- lxc/fs/proc/task_mmu.c~pagemap-use-PAGE_MASK	2007-08-07 15:30:52.000000000 -0700
> +++ lxc-dave/fs/proc/task_mmu.c	2007-08-07 15:30:52.000000000 -0700
> @@ -669,9 +669,9 @@ static ssize_t pagemap_read(struct file 
>  		goto out;
>  
>  	ret = -ENOMEM;
> -	uaddr = (unsigned long)buf & ~(PAGE_SIZE-1);
> +	uaddr = (unsigned long)buf & PAGE_MASK;
>  	uend = (unsigned long)(buf + count);
> -	pagecount = (uend - uaddr + PAGE_SIZE-1) / PAGE_SIZE;
> +	pagecount = (uend - PAGE_ALIGN(uaddr)) / PAGE_SIZE;

Unless I'm missing something the PAGE_ALIGN as ist stands is now a NOP
because uaddr is already page aligned. You probably wanted to
PAGE_ALIGN(uend). However, this will likely add an additional instruction
to the generated code.

    regards  Christian


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