Re: [PATCH] arm64: smp: smp_send_stop() and crash_smp_send_stop() should try non-NMI first

[Doug Anderson]

Hi,

On Fri, Mar 1, 2024 at 8:06 AM Mark Rutland <mark.rutland@xxxxxxx> wrote:
>
> Hi Doug,
>
> On Tue, Feb 27, 2024 at 04:57:31PM -0800, Doug Anderson wrote:
> > On Mon, Jan 8, 2024 at 4:54 PM Doug Anderson <dianders@chromiumorg> wrote:
> > > On Thu, Dec 7, 2023 at 5:03 PM Douglas Anderson <dianders@xxxxxxxxxxxx> wrote:
>
> > > The sound of crickets is overwhelming. ;-) Does anyone have any
> > > comments here? Is this a terrible idea? Is this the best idea you've
> > > heard all year (it's only been 8 days, so maybe)? Is this great but
> > > the implementation is lacking (at best)? Do you hate that this waits
> > > for 1 second and wish it waited for 1 ms? 10 ms? 100 ms? 8192 ms?
> > >
> > > Aside from the weirdness of a processor being killed while holding the
> > > console lock, it does seem beneficial to give IRQs at least a little
> > > time to finish before killing a processor. I don't have any other
> > > explicit examples, but I could just imagine that things might be a
> > > little more orderly in such a case...
> >
> > I'm still hoping to get some sort of feedback here. If people think
> > this is a terrible idea then I'll shut up now and leave well enough
> > alone, but it would be nice to actively decide and get the patch out
> > of limbo.
> >
> > FWIW the serial console dumping issue that originally inspired me to
> > track this down has been worked around at least well enough to not
> > spew garbage in my console. See commit 9e957a155005 ("serial:
> > qcom-geni: Don't cancel/abort if we can't get the port lock"). It's
> > still a little awkward because we'll be running fully lockless during
> > panic time, but it seems to work...
>
> This is on my list of things to look into, but I haven't had the chance to go
> through it in detail.
>
> From a high level, I think this sounds reasonable; I just want to make sure
> this doesn't lead to any new surprises...

Sounds good. For now I'll snooze this for another 2 months and if I
haven't heard from you then I'll pester you again. There's no crazy
hurry, I was just hoping for some sort of decision one way or the
other. For now I'll hold off on changing things to match x86 exactly
until I get your take on it too.

-Doug