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

From: Christian Ehrhardt
Date: Wed Aug 08 2007 - 03:45:20 EST


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


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/