The serial driver set the value of uart_8250_port.fcr in the function serial8250_config_port, but only writes the value to the controller register later in the initalization code. That opens a small window in which is not safe to use the fifo for console write. Make sure the port is initialized correctly before reading the FCR cached value. Unfortunately, I lost track of who originally reported the issue. If s/he is reading this, please speak up so I can give you the due credit. Signed-off-by: Wander Lairson Costa <wander@xxxxxxxxxx> --- drivers/tty/serial/8250/8250_port.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 4acf620be241..7e2227161555 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -3416,6 +3416,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, !(up->capabilities & UART_CAP_MINI) && up->tx_loadsz > 1 && (up->fcr & UART_FCR_ENABLE_FIFO) && + test_bit(TTY_PORT_INITIALIZED, &port->state->port.iflags) && /* * After we put a data in the fifo, the controller will send * it regardless of the CTS state. Therefore, only use fifo -- 2.35.1
