Re: WARN_ON() in netconsole with PREEMPT_RT

[Oleksandr Natalenko]

Hi.

On 12.11.2018 03:01, Steven Rostedt wrote:
> On Sun, 11 Nov 2018 21:16:00 +0100
> Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx> wrote:
> > Oh, I see that write_msg() calls netpoll_send_udp() under
> > spin_lock_irqsave(), but in PREEMPT_RT this, AFAIK, does not disable
> > interrupts.
> >
> > So, the real question here is whether the interrupts should be indeed
> > disabled. And if so, -rt should replace spin_lock_irqsave() call there
> > with what? local_irq_save()? and get rid of the warning?
>
> Why do we care if interrupts are disabled with PREEMPT_RT here?

I don't know, if you ask me. But the check was added intentionally with 
c9fd56b34efd0, so the author had definitely something on his mind. 
Cc'ing him.

> printk() itself has a lot of issues with PREEMPT_RT that we are working
> on dealing with. Right now netconsole is actually at the end of that
> todo list.

OK, I see.

--
  Oleksandr Natalenko (post-factum)