Re: [PATCH v4 0/4] Cleaning printk stuff in NMI context

From: Petr Mladek
Date: Mon Feb 08 2016 - 11:38:28 EST


On Thu 2016-01-21 12:30:07, Petr Mladek wrote:
> On Wed 2016-01-20 13:17:13, Andrew Morton wrote:
> > On Fri, 11 Dec 2015 14:20:48 +0100 Petr Mladek <pmladek@xxxxxxxx> wrote:
> >
> > > this is just a quick respin of the previous version. It changes
> > > the few details as you suggested. Also it fixes the build problem
> > > on ARM as reported by Geert and Arnd.
> > >
> > > I rather send the whole patch set because there is the renamed header.
> > > Also the extra blank space affects two patches. I hope that it will
> > > safe you some work. Please, let me know if you would prefer
> > > incremental patches.
> > >
> > >
> > > Changes against v3:
> > >
> > > + used size_t for "len" and "size"
> > >
> > > + replaced WARN() with pr_err()
> > >
> > > + renamed kernel/printk/printk.h -> internal.h
> > >
> > > + fixed build on ARM (undefined NMI_LOG_BUF_SHIFT)
> >
> > So the review of the v3 patchset was ... inconclusive. And everyone has
> > gone quiet about v4.
> >
> > Probably because you didn't cc the V3 discussion participants when
> > sending out V4. Big mistake, sorry, I can't check everything!
>
> Ah, v4 was sent too fast after v3 before others reacted. It included
> rather cosmetic changes based on your (Andrew's) feedback.
>
>
> > But v4 is basically unaltered from v3 so can we please rev this up
> > again? yay or nay? Thanks.
>
> The patch set prevents deadlocks that happen in a real life. It
> increases a chance to get a valid crash dump when NMI is involved.
>
> It does not handle well the situation when NMI is involved and
> the crash dump could not get produced. But this is not handled
> well even now. As Peter Zijlstra writes this a usually a real
> mess when he needs to use special hacks (early_printk) anyway.
>
> I still believe that the patch set makes sense and is acceptable
> as is.

Is anyone against getting this into the mainline for 4.6, please?

Best Regards,
Petr