On Tue, 2 Apr 2024 18:38:07 +0300
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
Hi Andy,
> uart_handle_cts_change() has to be called with port lock taken,
> Since we run it in a separate work, the lcok maybe not taken at
lcok -> lock
and possibly: "may not be taken" ?
> the time of running. Make sure that it's taken by explicitly doing
> that. Without it we got a splat:
>
> WARNING: CPU: 0 PID: 10 at drivers/tty/serial/serial_core.c:3491 uart_handle_cts_change+0xa6/0xb0
> ...
> Workqueue: max3100-0 max3100_work [max3100]
> RIP: 0010:uart_handle_cts_change+0xa6/0xb0
> ...
> max3100_handlerx+0xc5/0x110 [max3100]
> max3100_work+0x12a/0x340 [max3100]
>
> Fixes: 7831d56b0a35 ("tty: MAX3100")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> ---
> drivers/tty/serial/max3100.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/max3100.c b/drivers/tty/serial/max3100.c
> index 5efb2b593be3..45022f2909f0 100644
> --- a/drivers/tty/serial/max3100.c
> +++ b/drivers/tty/serial/max3100.c
> @@ -213,7 +213,7 @@ static int max3100_sr(struct max3100_port *s, u16 tx, u16 *rx)
> return 0;
> }
>
> -static int max3100_handlerx(struct max3100_port *s, u16 rx)
> +static int max3100_handlerx_unlocked(struct max3100_port *s, u16 rx)
> {
> unsigned int status = 0;
> int ret = 0, cts;
> @@ -254,6 +254,17 @@ static int max3100_handlerx(struct max3100_port *s, u16 rx)
> return ret;
> }
>
> +static int max3100_handlerx(struct max3100_port *s, u16 rx)
> +{
> + unsigned long flags;
> + int ret;
> +
> + uart_port_lock_irqsave(&s->port, &flags);
> + ret = max3100_handlerx_unlocked(s, rx);
> + uart_port_unlock_irqrestore(&s->port, flags);
> + return ret;
> +}
> +
> static void max3100_work(struct work_struct *w)
> {
> struct max3100_port *s = container_of(w, struct max3100_port, work);
> --
> 2.43.0.rc1.1.gbec44491f096
>
>
--
Hugo Villeneuve
