From: Fushuai Wang <wangfushuai@baidu.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@baidu.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