[PATCH v4 5/8] reboot: Replace strncmp with str_has_prefix

[Chuhong Yuan <hslester96@gmail.com>]

strncmp(str, const, len) is error-prone because len
is easy to have typo.
The example is the hard-coded len has counting error
or sizeof(const) forgets - 1.
So we prefer using newly introduced str_has_prefix()
to substitute such strncmp to make code better.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
---
Changes in v4:
  - Eliminate assignments in if conditions.

 kernel/reboot.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/reboot.c b/kernel/reboot.c
index c4d472b7f1b4..c79aaac43785 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -520,6 +520,8 @@ EXPORT_SYMBOL_GPL(orderly_reboot);
 
 static int __init reboot_setup(char *str)
 {
+	size_t len;
+
 	for (;;) {
 		enum reboot_mode *mode;
 
@@ -530,9 +532,10 @@ static int __init reboot_setup(char *str)
 		 */
 		reboot_default = 0;
 
-		if (!strncmp(str, "panic_", 6)) {
+		len = str_has_prefix(str, "panic_");
+		if (len) {
 			mode = &panic_reboot_mode;
-			str += 6;
+			str += len;
 		} else {
 			mode = &reboot_mode;
 		}
-- 
2.20.1