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

[Jiri Slaby]

On 27. 10. 26, 14:02, Ilpo Järvinen wrote:
> On Tue, 27 Oct 2026, Greg Kroah-Hartman wrote:
>
> > From: Josef Bacik <josef@xxxxxxxxxxxxxx>
> >
> > 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@xxxxxxxxxx>
> > Cc: Jiri Slaby <jirislaby@xxxxxxxxxx>
> > Cc: Maxime Coquelin <mcoquelin.stm32@xxxxxxxxx>
> > Cc: Alexandre Torgue <alexandre.torgue@xxxxxxxxxxx>
> > Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> > Cc: Vladimir Zapolskiy <vladimir_zapolskiy@xxxxxxxxxx>
> > Cc: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > ---
> >   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.

Likely. Or use scoped_guard(tty_port_tty) at minimum.

thanks,
--
js
suse labs