[PATCH 1/4] serial: 8250: Avoid error message on reprobe

[Lukas Wunner <lukas@wunner.de>]

If the call to uart_add_one_port() in serial8250_register_8250_port()
fails, a half-initialized entry in the serial_8250ports[] array is left
behind.

A subsequent reprobe of the same serial port causes that entry to be
reused.  Because uart->port.dev is set, uart_remove_one_port() is called
for the half-initialized entry and bails out with an error message:

bcm2835-aux-uart 3f215040.serial: Removing wrong port: (null) != (ptrval)

The same happens on failure of mctrl_gpio_init() since commit
4a96895f74c9 ("tty/serial/8250: use mctrl_gpio helpers").

Fix by zeroing the uart->port.dev pointer in the probe error path.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v2.6.10+
---
 drivers/tty/serial/8250/8250_core.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 45d9117cab68..14abade589da 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1040,7 +1040,7 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
 			gpios = mctrl_gpio_init(&uart->port, 0);
 			if (IS_ERR(gpios)) {
 				ret = PTR_ERR(gpios);
-				goto out_unlock;
+				goto err;
 			} else {
 				uart->gpios = gpios;
 			}
@@ -1089,7 +1089,9 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
 			serial8250_apply_quirks(uart);
 			ret = uart_add_one_port(&serial8250_reg,
 						&uart->port);
-			if (ret == 0)
+			if (ret)
+				goto err;
+			else
 				ret = uart->port.line;
 		} else {
 			dev_info(uart->port.dev,
@@ -1112,10 +1114,14 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
 		}
 	}
 
-out_unlock:
 	mutex_unlock(&serial_mutex);
 
 	return ret;
+
+err:
+	uart->port.dev = NULL;
+	mutex_unlock(&serial_mutex);
+	return ret;
 }
 EXPORT_SYMBOL(serial8250_register_8250_port);
 
-- 
2.26.2