Re: [PATCH 24/24] serial: stm32: don't report a wakeup to a closed tty

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Tue, 27 Oct 2026, Greg Kroah-Hartman wrote:

> From: Josef Bacik <josef@toxicpanda.com>
> 
> stm32_usart_interrupt() reports a wakeup interrupt as a wakeup event of
> tport->tty->dev.  That pointer is only set while the port is open.  The
> port of a console is not shut down by the last close: it stays
> initialized, so the wakeup interrupt is still enabled on suspend.  If
> the system is then woken up by the console, the handler dereferences a
> NULL pointer.
> 
> Take a reference to the tty, and leave the event out if there is none.
> 
> Fixes: 48a6092fb41f ("serial: stm32-usart: Add STM32 USART Driver")
> Cc: stable <stable@kernel.org>
> Cc: Jiri Slaby <jirislaby@kernel.org>
> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
> Cc: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
> Cc: Peter Hurley <peter@hurleysoftware.com>
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/tty/serial/stm32-usart.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
> index ad06b760cfca..3bc2ce877585 100644
> --- a/drivers/tty/serial/stm32-usart.c
> +++ b/drivers/tty/serial/stm32-usart.c
> @@ -872,8 +872,15 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
>  		writel_relaxed(USART_ICR_WUCF,
>  			       port->membase + ofs->icr);
>  		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_WUFIE);
> -		if (irqd_is_wakeup_set(irq_get_irq_data(port->irq)))
> -			pm_wakeup_event(tport->tty->dev, 0);
> +		if (irqd_is_wakeup_set(irq_get_irq_data(port->irq))) {
> +			struct tty_struct *tty = tty_port_tty_get(tport);
> +
> +			/* A console stays set up after the last close */
> +			if (tty) {
> +				pm_wakeup_event(tty->dev, 0);
> +				tty_kref_put(tty);
> +			}
> +		}

Could we like add a helper into serial core to do this tty wakeup dance? 
It is duplicated in quite many of these patches.


-- 
 i.