linux-kernel - Re: [PATCH 2/3] serial: qcom-geni: fix shutdown race

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Message-ID: <CAMRc=Md-B3MCdjBA6Z03Tn09Qdq_O=2Gij=0kr8HiLtpp11kVg@mail.gmail.com>
Date: Tue, 17 Sep 2024 17:13:07 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Johan Hovold <johan+linaro@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby <jirislaby@...nel.org>, 
	Douglas Anderson <dianders@...omium.org>, linux-arm-msm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org, 
	stable@...r.kernel.org, Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH 2/3] serial: qcom-geni: fix shutdown race

On Mon, Sep 16, 2024 at 7:27 PM Johan Hovold <johan+linaro@...nel.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@...r.kernel.org      # 6.3
> Cc: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> Signed-off-by: Johan Hovold <johan+linaro@...nel.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@...aro.org>