A commit adding back the stopping of tx on port shutdown failed to add
back the locking which had also been removed by commit e83766334f96
("tty: serial: qcom_geni_serial: No need to stop tx/rx on UART
shutdown").

Holding the port lock is needed to serialise against the console code,
which may update the interrupt enable register and access the port
state.

Fixes: d8aca2f96813 ("tty: serial: qcom-geni-serial: stop operations in progress at shutdown")
Fixes: 947cc4ecc06c ("serial: qcom-geni: fix soft lockup on sw flow control and suspend")
Cc: stable@vger.kernel.org	# 6.3
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/tty/serial/qcom_geni_serial.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 2e4a5361f137..87cd974b76bf 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -1114,10 +1114,12 @@ static void qcom_geni_serial_shutdown(struct uart_port *uport)
 {
 	disable_irq(uport->irq);
 
+	uart_port_lock_irq(uport);
 	qcom_geni_serial_stop_tx(uport);
 	qcom_geni_serial_stop_rx(uport);
 
 	qcom_geni_serial_cancel_tx_cmd(uport);
+	uart_port_unlock_irq(uport);
 }
 
 static void qcom_geni_serial_flush_buffer(struct uart_port *uport)
-- 
2.45.2

Hi,

On Wed, Oct 9, 2024 at 7:51 AM Johan Hovold <johan+linaro@kernel.org> wrote:
>
> A commit adding back the stopping of tx on port shutdown failed to add
> back the locking which had also been removed by commit e83766334f96
> ("tty: serial: qcom_geni_serial: No need to stop tx/rx on UART
> shutdown").
>
> Holding the port lock is needed to serialise against the console code,
> which may update the interrupt enable register and access the port
> state.
>
> Fixes: d8aca2f96813 ("tty: serial: qcom-geni-serial: stop operations in progress at shutdown")
> Fixes: 947cc4ecc06c ("serial: qcom-geni: fix soft lockup on sw flow control and suspend")
> Cc: stable@vger.kernel.org      # 6.3
> Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/tty/serial/qcom_geni_serial.c | 2 ++
>  1 file changed, 2 insertions(+)

Though this doesn't fix the preexisting bug I talked about [1] that
we'll need to touch the same code to fix:

Reviewed-by: Douglas Anderson <dianders@chromium.org>

[1] https://lore.kernel.org/r/CAD=FV=UZtZ1-0SkN2sOMp6YdU02em_RnK85Heg5z0jkH4U30eQ@mail.gmail.com

On Thu, Oct 10, 2024 at 03:36:30PM -0700, Doug Anderson wrote:
> On Wed, Oct 9, 2024 at 7:51 AM Johan Hovold <johan+linaro@kernel.org> wrote:
> >
> > A commit adding back the stopping of tx on port shutdown failed to add
> > back the locking which had also been removed by commit e83766334f96
> > ("tty: serial: qcom_geni_serial: No need to stop tx/rx on UART
> > shutdown").
> >
> > Holding the port lock is needed to serialise against the console code,
> > which may update the interrupt enable register and access the port
> > state.
> >
> > Fixes: d8aca2f96813 ("tty: serial: qcom-geni-serial: stop operations in progress at shutdown")
> > Fixes: 947cc4ecc06c ("serial: qcom-geni: fix soft lockup on sw flow control and suspend")
> > Cc: stable@vger.kernel.org      # 6.3
> > Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> > Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> > ---
> >  drivers/tty/serial/qcom_geni_serial.c | 2 ++
> >  1 file changed, 2 insertions(+)
> 
> Though this doesn't fix the preexisting bug I talked about [1] that
> we'll need to touch the same code to fix:
> 
> Reviewed-by: Douglas Anderson <dianders@chromium.org>

Yeah, let's address that separately. Thanks for reviewing!

Johan

> [1] https://lore.kernel.org/r/CAD=FV=UZtZ1-0SkN2sOMp6YdU02em_RnK85Heg5z0jkH4U30eQ@mail.gmail.com