serial: don't use uninitialized value in uart_poll_init()

Coverity reports (as CID 1536978) that uart_poll_init() passes
uninitialized pm_state to uart_change_pm(). It is in case the first 'if'
takes the true branch (does "goto out;").

Fix this and simplify the function by simple guard(mutex). The code
needs no labels after this at all. And it is pretty clear that the code
has not fiddled with pm_state at that point.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Fixes: 5e227ef2aa38 (serial: uart_poll_init() should power on the UART)
Cc: stable@vger.kernel.org
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20240805102046.307511-4-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 83c5bccc5086546eb5991afca80a3cce76bfb929..e0aac155dca2e7a972eb18e097a11590ccea5fb7 100644 (file)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2690,14 +2690,13 @@ static int uart_poll_init(struct tty_driver *driver, int line, char *options)
        int ret = 0;
 
        tport = &state->port;
-       mutex_lock(&tport->mutex);
+
+       guard(mutex)(&tport->mutex);
 
        port = uart_port_check(state);
        if (!port || port->type == PORT_UNKNOWN ||
-           !(port->ops->poll_get_char && port->ops->poll_put_char)) {
-               ret = -1;
-               goto out;
-       }
+           !(port->ops->poll_get_char && port->ops->poll_put_char))
+               return -1;
 
        pm_state = state->pm_state;
        uart_change_pm(state, UART_PM_STATE_ON);
@@ -2717,10 +2716,10 @@ static int uart_poll_init(struct tty_driver *driver, int line, char *options)
                ret = uart_set_options(port, NULL, baud, parity, bits, flow);
                console_list_unlock();
        }
-out:
+
        if (ret)
                uart_change_pm(state, pm_state);
-       mutex_unlock(&tport->mutex);
+
        return ret;
 }