From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id C4F7B6B01EF for ; Mon, 5 Apr 2010 22:40:34 -0400 (EDT) Received: by qyk33 with SMTP id 33so4927784qyk.28 for ; Mon, 05 Apr 2010 19:40:32 -0700 (PDT) From: Bob Liu Subject: [PATCH] __isolate_lru_page: change code style Date: Tue, 6 Apr 2010 10:40:22 +0800 Message-Id: <1270521622-8551-1-git-send-email-lliubbo@gmail.com> Sender: owner-linux-mm@kvack.org To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, kosaki.motohiro@jp.fujitsu.com, Bob Liu List-ID: As Andrew said: " it wouldn't be a good and maintainable change - one point in using enumerations such as ISOLATE_* is to hide their real values. Adding code which implicitly "knows" that a particular enumerated identifier has a particular underlying value is rather grubby and fragile. It's also a bit fragile to assume that a true/false-returning C function (PageActive) will always return 0 or 1. It's a common C idiom for such functions to return 0 or non-zero (not necessarily 1). So a clean and maintainable implementation of if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) return ret; would be if (mode != ISOLATE_BOTH && ((PageActive(page) && mode == ISOLATE_ACTIVE) || (!PageActive(page) && mode == ISOLATE_INACTIVE))) return ret; " I changed my "skip unneeded 'not' patch" following his idea. Signed-off-by: Bob Liu --- mm/vmscan.c | 9 +++------ 1 files changed, 3 insertions(+), 6 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index e0e5f15..9d1e52a 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -862,12 +862,9 @@ 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. - */ - if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) + if (mode != ISOLATE_BOTH && + ((PageActive(page) && mode == ISOLATE_ACTIVE) || + (!PageActive(page) && mode == ISOLATE_INACTIVE))) return ret; if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file) -- 1.5.6.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org