linux-kernel - Re: [PATCH] tty/serial: Cancel work queue before closing uart

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Date:   Thu, 24 Aug 2023 10:30:23 +0800
From:   wenhua lin <wenhua.lin1994@...il.com>
To:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc:     Wenhua Lin <Wenhua.Lin@...soc.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Orson Zhai <orsonzhai@...il.com>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        Chunyan Zhang <zhang.lyra@...il.com>,
        linux-serial <linux-serial@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Xiongpeng Wu <xiongpeng.wu@...soc.com>,
        Zhirong Qiu <zhirong.qiu@...soc.com>,
        Zhaochen Su <Zhaochen.Su@...soc.com>
Subject: Re: [PATCH] tty/serial: Cancel work queue before closing uart

On Tue, Aug 22, 2023 at 4:23 PM Ilpo Järvinen
<ilpo.jarvinen@...ux.intel.com> wrote:
>
> On Fri, 18 Aug 2023, Wenhua Lin wrote:
>
> I've problems following your description below due to grammar errors.
>
> > When the system constantly sleeps and wankes up, plugging and unplugging
>
> wakes
>
> > the USB will probalility trigger a kernel crash problem.
>
> probalility is typoed and I cannot guess which of the words you meant,
> please fix.
>
> If there's a known crash you're fixing here, please quote the crash
> message in the changelog (and you should probably add Fixes: tag too in
> that case).
>
> > The reason is
> > that at this time, the system entered deep and turned off uart, and the
>
> "entered deep" lacks probably some word?
>
> > abnormal behavior of plugging and upplugging the USB triggered the read
>
> unplugging.
>
> Why call that abnormal behavior? Isn't USB expected to removed.
>
> > data process of uart, causing access to uart to hang.
>
> Are you saying a read was triggered while the UART was suspended or what?
>
> > The final solution
> > we came up with is to cancel the work queue before shutting down uart
> > , while ensuring that there is no uart business.
>
> ", while ensuring" -> to ensure
>
> "uart business" is too vague, you should replace it with something more
> concrete.

We will fix it in patch v2, thank you  for your review.

>
> Thanks.
>
> --
>  i.
>
> >
> > Signed-off-by: Wenhua Lin <Wenhua.Lin@...soc.com>
> > ---
> >  drivers/tty/serial/sprd_serial.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
> > index b58f51296ace..eddff4360155 100644
> > --- a/drivers/tty/serial/sprd_serial.c
> > +++ b/drivers/tty/serial/sprd_serial.c
> > @@ -20,6 +20,7 @@
> >  #include <linux/slab.h>
> >  #include <linux/tty.h>
> >  #include <linux/tty_flip.h>
> > +#include "../tty.h"
> >
> >  /* device name */
> >  #define UART_NR_MAX          8
> > @@ -1221,7 +1222,10 @@ static int sprd_probe(struct platform_device *pdev)
> >  static int sprd_suspend(struct device *dev)
> >  {
> >       struct sprd_uart_port *sup = dev_get_drvdata(dev);
> > +     struct uart_port *uport = &sup->port;
> > +     struct tty_port *tty = &uport->state->port;
> >
> > +     tty_buffer_cancel_work(tty);
> >       uart_suspend_port(&sprd_uart_driver, &sup->port);
> >
> >       return 0;
> >