The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e0a851fe6b9b619527bd928aa93caaddd003f70c Mon Sep 17 00:00:00 2001

From: Lukas Wunner lukas@wunner.de Date: Tue, 12 May 2020 14:40:01 +0200 Subject: [PATCH] serial: 8250: Avoid error message on reprobe

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.

The bug was introduced in v2.6.10 by historical commit befff6f5bf5f ("[SERIAL] Add new port registration/unregistration functions."): https://git.kernel.org/tglx/history/c/befff6f5bf5f

The commit added an unconditional call to uart_remove_one_port() in serial8250_register_port(). In v3.7, commit 835d844d1a28 ("8250_pnp: do pnp probe before legacy probe") made that call conditional on uart->port.dev which allows me to fix the issue by zeroing that pointer in the error path. Thus, the present commit will fix the problem as far back as v3.7 whereas still older versions need to also cherry-pick 835d844d1a28.

Fixes: 835d844d1a28 ("8250_pnp: do pnp probe before legacy probe") Signed-off-by: Lukas Wunner lukas@wunner.de Cc: stable@vger.kernel.org # v2.6.10 Cc: stable@vger.kernel.org # v2.6.10: 835d844d1a28: 8250_pnp: do pnp probe before legacy Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Link: https://lore.kernel.org/r/b4a072013ee1a1d13ee06b4325afb19bda57ca1b.158928587... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index 45d9117cab68..9548d3f8fc8e 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; } @@ -1089,8 +1089,10 @@ 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) - ret = uart->port.line; + if (ret) + goto err; + + ret = uart->port.line; } else { dev_info(uart->port.dev, "skipping CIR port at 0x%lx / 0x%llx, IRQ %d\n", @@ -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);