linux-kernel - [PATCH] mm: avoid possible multiple call to swap

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Message-ID: <20200917114449.35285-1-linmiaohe@huawei.com>
Date:   Thu, 17 Sep 2020 07:44:49 -0400
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH] mm: avoid possible multiple call to swap_node()

Cache the swap_node() in a local variable to avoid possible multiple call
to swap_node(), though compiler may do this for us.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/swapfile.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 20012c0c0252..cd66b50f0490 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2454,7 +2454,7 @@ static void setup_swap_info(struct swap_info_struct *p, int prio,
 			    unsigned char *swap_map,
 			    struct swap_cluster_info *cluster_info)
 {
-	int i;
+	int i, node;
 
 	if (prio >= 0)
 		p->prio = prio;
@@ -2465,11 +2465,12 @@ static void setup_swap_info(struct swap_info_struct *p, int prio,
 	 * low-to-high, while swap ordering is high-to-low
 	 */
 	p->list.prio = -p->prio;
+	node = swap_node(p);
 	for_each_node(i) {
 		if (p->prio >= 0)
 			p->avail_lists[i].prio = -p->prio;
 		else {
-			if (swap_node(p) == i)
+			if (node == i)
 				p->avail_lists[i].prio = 1;
 			else
 				p->avail_lists[i].prio = -p->prio;
-- 
2.19.1