The port->console flag is always false, as uart_console() is called
before the serial console has been registered.
Hence for a serial port used as the console, uart_tty_port_shutdown()
will still be called when userspace closes the port, powering it down.
This will lead to a system lock up when the serial console driver writes
to the serial port's registers.
To fix this, move the setting of port->console after the call to
uart_configure_port(), which registers the serial console.
Fixes: 761ed4a94582ab29 ("tty: serial_core: convert uart_close to use tty_port_close")
Reported-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
Reported-by: Takeshi Kihara <takeshi.kihara.df@xxxxxxxxxxx>
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
---
RFC because of the comment "If this port is a console, then the spinlock
is already initialised", and the pre-existing code calling
uart_console() before uart_configure_port().
Can be reproduced on Renesas boards:
1. With systemd: hangs during boot,
2. Without systemd: "telinit n" to switch to a runlevel that doesn't
run a getty on ttySC0, and trigger kernel output.
---
drivers/tty/serial/serial_core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 6e4f63627479db8d..ce8899c13af3d97f 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2746,8 +2746,6 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
uport->cons = drv->cons;
uport->minor = drv->tty_driver->minor_start + uport->line;
- port->console = uart_console(uport);
-
/*
* If this port is a console, then the spinlock is already
* initialised.
@@ -2761,6 +2759,8 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
uart_configure_port(drv, state, uport);
+ port->console = uart_console(uport);
+
num_groups = 2;
if (uport->attr_group)
num_groups++;
--
1.9.1
