[PATCH] USB: serial: f81534: Detect errors from f81534_logic_to_phy_port()

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Johan Hovold <johan@kernel.org>,
	"Ji-Ze Hong (Peter Hong)" <hpeter@gmail.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	Geert Uytterhoeven <geert@linux-m68k.org>
Subject: [PATCH] USB: serial: f81534: Detect errors from f81534_logic_to_phy_port()
Date: Wed, 14 Dec 2016 12:18:53 +0100	[thread overview]
Message-ID: <1481714333-14014-1-git-send-email-geert@linux-m68k.org> (raw)

With gcc 4.1.2:

    drivers/usb/serial/f81534.c: In function ‘f81534_port_probe’:
    drivers/usb/serial/f81534.c:1250: warning: comparison is always false due to limited range of data type

f81534_logic_to_phy_port() may return a negative error value, which is
ignored by assigning it to u8 f81534_port_private.phy_num.

Use an intermediate variable of type int to fix this.
While at it, forward the actual error code instead of converting it to
-ENODEV.

Fixes: 0c9bd6004d258d46 ("USB: serial: add Fintek F81532/534 driver")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
 drivers/usb/serial/f81534.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/serial/f81534.c b/drivers/usb/serial/f81534.c
index 8282a6a18fee83f6..2acad268f9d15f43 100644
--- a/drivers/usb/serial/f81534.c
+++ b/drivers/usb/serial/f81534.c
@@ -1237,6 +1237,7 @@ static int f81534_attach(struct usb_serial *serial)
 static int f81534_port_probe(struct usb_serial_port *port)
 {
 	struct f81534_port_private *port_priv;
+	int ret;
 
 	port_priv = devm_kzalloc(&port->dev, sizeof(*port_priv), GFP_KERNEL);
 	if (!port_priv)
@@ -1246,10 +1247,14 @@ static int f81534_port_probe(struct usb_serial_port *port)
 	mutex_init(&port_priv->mcr_mutex);
 
 	/* Assign logic-to-phy mapping */
-	port_priv->phy_num = f81534_logic_to_phy_port(port->serial, port);
-	if (port_priv->phy_num < 0 || port_priv->phy_num >= F81534_NUM_PORT)
+	ret = f81534_logic_to_phy_port(port->serial, port);
+	if (ret < 0)
+		return ret;
+
+	if (ret >= F81534_NUM_PORT)
 		return -ENODEV;
 
+	port_priv->phy_num = ret;
 	usb_set_serial_port_data(port, port_priv);
 	dev_dbg(&port->dev, "%s: port_number: %d, phy_num: %d\n", __func__,
 			port->port_number, port_priv->phy_num);
-- 
1.9.1
