linux-kernel - [PATCH -mm] mm: Improve readability of clear_huge

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Date:   Wed, 30 Aug 2017 13:18:42 +0800
From:   "Huang, Ying" <ying.huang@...el.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Huang Ying <ying.huang@...el.com>
Subject: [PATCH -mm] mm: Improve readability of clear_huge_page

From: Huang Ying <ying.huang@...el.com>

The optimized clear_huge_page() isn't easy to read and understand.
This is suggested by Michael Hocko to improve it.

Suggested-by: Michal Hocko <mhocko@...e.com>
Signed-off-by: "Huang, Ying" <ying.huang@...el.com>
---
 mm/memory.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 20ac58c128e9..694ddbd3a020 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4507,12 +4507,15 @@ void clear_huge_page(struct page *page,
 	 * towards the sub-page to access
 	 */
 	for (i = 0; i < l; i++) {
+		int left_idx = base + i;
+		int right_idx = base + 2 * l - 1 - i;
+
 		cond_resched();
-		clear_user_highpage(page + base + i,
-				    addr + (base + i) * PAGE_SIZE);
+		clear_user_highpage(page + left_idx,
+				    addr + left_idx * PAGE_SIZE);
 		cond_resched();
-		clear_user_highpage(page + base + 2 * l - 1 - i,
-				    addr + (base + 2 * l - 1 - i) * PAGE_SIZE);
+		clear_user_highpage(page + right_idx,
+				    addr + right_idx * PAGE_SIZE);
 	}
 }
 
-- 
2.13.2