Re: [PATCH] serial: base: do not disable TX on hangup for console ports

[kpursoty]

Thanks for your notes. Patch withdrawn.

On Wednesday, 15 April 2026 at 09:01, kpursoty@xxxxxxxxx <kpursoty@xxxxxxxxx> wrote:

> serial_base_port_shutdown() calls serial_base_port_set_tx(false)
> unconditionally. When a TTY hangup occurs on a port that is also a
> registered kernel console, this permanently disables the console
> transmitter.
>
> uart_hangup() already guards against uart_change_pm(PM_OFF) for console
> ports (see the uart_console() check in uart_hangup()). Apply the same
> guard in serial_base_port_shutdown(): skip TX-disable if the port is a
> registered console.
>
> Without this fix, any path that calls uart_shutdown() on a console port
> - including TIOCSCTTY with force=1 (as used by init systems such as
> procd) - permanently silences all subsequent kernel console output.
>
> Signed-off-by: Kervin Pursoty <kpursoty@xxxxxxxxx>
> ---
>  drivers/tty/serial/serial_port.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/serial_port.c b/drivers/tty/serial/serial_port.c
> --- a/drivers/tty/serial/serial_port.c
> +++ b/drivers/tty/serial/serial_port.c
> @@ -110,5 +110,14 @@
>  {
>  	struct serial_port_device *port_dev = port->port_dev;
>
> -	serial_base_port_set_tx(port, port_dev, false);
> +	/*
> +	 * Do not disable TX on a console port. When an init system calls
> +	 * TIOCSCTTY with force=1, the kernel hangs up the previous session,
> +	 * triggering uart_hangup() -> uart_shutdown() -> here. Stopping TX
> +	 * kills all kernel console output permanently.
> +	 * uart_hangup() already skips uart_change_pm(PM_OFF) for consoles
> +	 * via uart_console(); apply the same guard here.
> +	 */
> +	if (!uart_console(port))
> +		serial_base_port_set_tx(port, port_dev, false);
>  }
>
>  static DEFINE_RUNTIME_DEV_PM_OPS(serial_port_pm,
>