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.

The call to stop rx that was added by the same commit is redundant as
serial core will already have taken care of that and can thus be
removed.

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
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/tty/serial/qcom_geni_serial.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 9ea6bd09e665..88ad5a6e7de2 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -1096,10 +1096,10 @@ 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)
-- 
2.44.2

On Mon, Sep 16, 2024 at 7:27 PM 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.
>
> The call to stop rx that was added by the same commit is redundant as
> serial core will already have taken care of that and can thus be
> removed.
>
> 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
> Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/tty/serial/qcom_geni_serial.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
> index 9ea6bd09e665..88ad5a6e7de2 100644
> --- a/drivers/tty/serial/qcom_geni_serial.c
> +++ b/drivers/tty/serial/qcom_geni_serial.c
> @@ -1096,10 +1096,10 @@ 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)
> --
> 2.44.2
>
>

Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>