linux-kernel - [PATCH v2 2/2] x86/tlb: Convert copy_from_user() + kstrtouint() to kstrtouint_from

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Message-Id: <20260117145615.53455-3-fushuai.wang@linux.dev>
Date: Sat, 17 Jan 2026 22:56:15 +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 v2 2/2] x86/tlb: 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.

Suggested-by: Yury Norov <ynorov@...dia.com>
Signed-off-by: Fushuai Wang <wangfushuai@...du.com>
Reviewed-by: Yury Norov <ynorov@...dia.com>
---
 arch/x86/mm/tlb.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index f5b93e01e347..5e6a07306214 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -1802,17 +1802,12 @@ static ssize_t tlbflush_read_file(struct file *file, char __user *user_buf,
 static ssize_t tlbflush_write_file(struct file *file,
 		 const char __user *user_buf, size_t count, loff_t *ppos)
 {
-	char buf[32];
-	ssize_t len;
 	int ceiling;
+	int err;
 
-	len = min(count, sizeof(buf) - 1);
-	if (copy_from_user(buf, user_buf, len))
-		return -EFAULT;
-
-	buf[len] = '\0';
-	if (kstrtoint(buf, 0, &ceiling))
-		return -EINVAL;
+	err = kstrtoint_from_user(user_buf, count, 0, &ceiling);
+	if (err)
+		return err;
 
 	if (ceiling < 0)
 		return -EINVAL;
-- 
2.36.1