[stable-kernel][5.15.y][PATCH 2/5] serial: sc16is7xx: remove wasteful static buffer in sc16is7xx_regmap_name()

[Hui Wang <hui.wang@canonical.com>]

From: Hugo Villeneuve <hvilleneuve@dimonoff.com>

commit 6bcab3c8acc88e265c570dea969fd04f137c8a4c upstream.

Using a static buffer inside sc16is7xx_regmap_name() was a convenient and
simple way to set the regmap name without having to allocate and free a
buffer each time it is called. The drawback is that the static buffer
wastes memory for nothing once regmap is fully initialized.

Remove static buffer and use constant strings instead.

This also avoids a truncation warning when using "%d" or "%u" in snprintf
which was flagged by kernel test robot.

Fixes: 3837a0379533 ("serial: sc16is7xx: improve regmap debugfs by using one regmap per port")
Cc:  <stable@vger.kernel.org> # 6.1.x: 3837a03 serial: sc16is7xx: improve regmap debugfs by using one regmap per port
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20231211171353.2901416-2-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Hui Wang <hui.wang@canonical.com>
---
 drivers/tty/serial/sc16is7xx.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 88adbd9d5002..35001cc7ec90 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1450,13 +1450,15 @@ static struct regmap_config regcfg = {
 	.max_register = SC16IS7XX_EFCR_REG,
 };
 
-static const char *sc16is7xx_regmap_name(unsigned int port_id)
+static const char *sc16is7xx_regmap_name(u8 port_id)
 {
-	static char buf[6];
-
-	snprintf(buf, sizeof(buf), "port%d", port_id);
-
-	return buf;
+	switch (port_id) {
+	case 0:	return "port0";
+	case 1:	return "port1";
+	default:
+		WARN_ON(true);
+		return NULL;
+	}
 }
 
 static unsigned int sc16is7xx_regmap_port_mask(unsigned int port_id)
-- 
2.34.1