linux-kernel - [PATCH 1/2] sched/debug: Convert copy_from_user() + kstrtouint() to kstrtouint_from

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Message-Id: <20260116131751.45768-2-fushuai.wang@linux.dev>
Date: Fri, 16 Jan 2026 21:17:50 +0800
From: Fushuai Wang <fushuai.wang@...ux.dev>
To: mingo@...hat.com,
	peterz@...radead.org,
	juri.lelli@...hat.com,
	vincent.guittot@...aro.org,
	dietmar.eggemann@....com,
	rostedt@...dmis.org,
	bsegall@...gle.com,
	mgorman@...e.de,
	vschneid@...hat.com,
	dave.hansen@...ux.intel.com,
	luto@...nel.org,
	tglx@...nel.org,
	bp@...en8.de,
	hpa@...or.com
Cc: linux-kernel@...r.kernel.org,
	x86@...nel.org,
	wangfushuai@...du.com,
	aliceryhl@...gle.com,
	ynorov@...dia.com
Subject: [PATCH 1/2] sched/debug: Convert copy_from_user() + kstrtouint() to kstrtouint_from_user()

From: Fushuai Wang <wangfushuai@...du.com>

Using kstrtouint_from_user() instead of copy_from_user() + kstrtouint()
makes the code simpler and less error-prone.

Signed-off-by: Fushuai Wang <wangfushuai@...du.com>
---
 kernel/sched/debug.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 41caa22e0680..1091f9046260 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -172,18 +172,12 @@ static const struct file_operations sched_feat_fops = {
 static ssize_t sched_scaling_write(struct file *filp, const char __user *ubuf,
 				   size_t cnt, loff_t *ppos)
 {
-	char buf[16];
 	unsigned int scaling;
+	int ret;
 
-	if (cnt > 15)
-		cnt = 15;
-
-	if (copy_from_user(&buf, ubuf, cnt))
-		return -EFAULT;
-	buf[cnt] = '\0';
-
-	if (kstrtouint(buf, 10, &scaling))
-		return -EINVAL;
+	ret = kstrtouint_from_user(ubuf, cnt, 10, &scaling);
+	if (ret < 0)
+		return ret;
 
 	if (scaling >= SCHED_TUNABLESCALING_END)
 		return -EINVAL;
-- 
2.36.1