linux-kernel - [PATCH V1 1/2] mm/damon/sysfs: avoid call damon_target_has

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Message-Id: <20220915142237.92529-1-xhao@linux.alibaba.com>
Date:   Thu, 15 Sep 2022 22:22:36 +0800
From:   Xin Hao <xhao@...ux.alibaba.com>
To:     sj@...nel.org
Cc:     akpm@...ux-foundation.org, damon@...ts.linux.dev,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        xhao@...ux.alibaba.com
Subject: [PATCH V1 1/2] mm/damon/sysfs: avoid call damon_target_has_pid() repeatedly

In damon_sysfs_destroy_targets(), we call damon_target_has_pid() to
check whether the 'ctx' include a valid pid, but there no need to call
damon_target_has_pid() to check repeatedly, just need call it once.

Signed-off-by: Xin Hao <xhao@...ux.alibaba.com>
---
 mm/damon/sysfs.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 1fa0023f136e..966ea7892ccf 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -2143,9 +2143,13 @@ static int damon_sysfs_set_attrs(struct damon_ctx *ctx,
 static void damon_sysfs_destroy_targets(struct damon_ctx *ctx)
 {
 	struct damon_target *t, *next;
+	bool has_pid = false;
+
+	if (damon_target_has_pid(ctx))
+		has_pid = true;

 	damon_for_each_target_safe(t, next, ctx) {
-		if (damon_target_has_pid(ctx))
+		if (has_pid)
 			put_pid(t->pid);
 		damon_destroy_target(t);
 	}
--
2.31.0