Re: [PATCH printk v2 2/2] printk: Avoid scheduling irq_work on suspend

[Derek Barbosa]

Hi John,

On Thu, Nov 13, 2025 at 06:12:57PM +0106, John Ogness wrote:
> 
> I assume the problem you are seeing is with the PREEMPT_RT patches
> applied (i.e. with the 8250-NBCON included). If that is the case, note
> that recent versions of the 8250 driver introduce its own irq_work that
> is also problematic. I am currently reworking the 8250-NBCON series so
> that it does not introduce irq_work.
> 

IIRC the aforementioned scenario was just recently tested with an rc5 kernel
from Torvalds' tree. Sorry for any confusion

> Since you probably are not doing anything related to modem control,
> maybe you could test with the following hack (assuming you are using a
> v6.14 or later PREEMPT_RT patched kernel).

I'll give this a shot as a follow up, thanks for the suggestion

> 
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 96d32db9f8872..2ad0f91ad467a 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -3459,7 +3459,7 @@ void serial8250_console_write(struct uart_8250_port *up,
>  		 * may be a context that does not permit waking up tasks.
>  		 */
>  		if (is_atomic)
> -			irq_work_queue(&up->modem_status_work);
> +			;//irq_work_queue(&up->modem_status_work);
>  		else
>  			serial8250_modem_status(up);
>  	}
> 
> > [0] https://github.com/Linutronix/linux/commit/ae173249d9028ef159fba040bdab260d80dda43f
> 
> John
> 

-- 
Derek <debarbos@xxxxxxxxxx>