On Thu, 1 Apr 2010 21:37:35 +0800
Bob Liu <lliubbo@xxxxxxxxx> wrote:
> PageActive(page) will return int 0 or 1, mode is also int 0 or 1,
> they are comparible so "not" is unneeded to be sure to boolean
> values.
> I also collected the ISOLATE_BOTH check together.
>
> Signed-off-by: Bob Liu <lliubbo@xxxxxxxxx>
> ---
> mm/vmscan.c | 15 +++++----------
> 1 files changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index e0e5f15..ce9ee85 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -862,16 +862,11 @@ int __isolate_lru_page(struct page *page, int mode, int file)
> if (!PageLRU(page))
> return ret;
>
> - /*
> - * When checking the active state, we need to be sure we are
> - * dealing with comparible boolean values. Take the logical not
> - * of each.
> - */
You deleted a spelling mistake too!
> - if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
> - return ret;
> -
> - if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file)
> - return ret;
> + if (mode != ISOLATE_BOTH) {
> + if ((PageActive(page) != mode) ||
> + (page_is_file_cache(page) != file))
> + return ret;
> + }
The compiler should be able to avoid testing for ISOLATE_BOTH twice,
and I think the previous code layout was superior:
if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
return ret;
if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file)
return ret;
Because it gives us nice places to put a comment explaining what the
code is doing, whereas making it a more complex single expression:
if (mode != ISOLATE_BOTH) {
if ((PageActive(page) != mode) ||
(page_is_file_cache(page) != file))
return ret;
}
makes clearly commenting each test more difficult.
Yeah, there's no comment there at present. But that's because we suck
- I'm sure someone is working on it ;)
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>