linux-kernel - Re: Atomicity in KMS panic notifier

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Message-ID: <s5hha53ujeq.wl%tiwai@suse.de>
Date:	Tue, 06 May 2014 15:27:25 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	Daniel Vetter <daniel@...ll.ch>
Cc:	dri-devel <dri-devel@...ts.freedesktop.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	David Herrmann <dh.herrmann@...il.com>
Subject: Re: Atomicity in KMS panic notifier

At Mon, 5 May 2014 16:52:45 +0200,
Daniel Vetter wrote:
> 
> On Mon, May 5, 2014 at 4:48 PM, Takashi Iwai <tiwai@...e.de> wrote:
> >
> > The current problem I see is that the rest of panic notifier chain
> > won't be called once when we hit the problem in KMS notifier.  So,
> > this bug in KMS influences on the rest panic behavior.
> >
> > Maybe a hackish solution would be to keep KMS notifier at the end of
> > notifier chain so that it crashes at last.  I don't like this either,
> > but...
> 
> You need to do that with both the kms panic notifier in
> drm_fb_helper.c and with the fbcon panic notifier. And iirc there's
> also a console->unblank call somewhere which _also_ can end up in
> ->set_par. But I'm not sure anymore when exactly that one is run, I've
> tried hard to forget this all ;-)

Looking back at the code again, it seems that fbcon has no panic
notifier.  It has own notifier chain, but it's a private chain that
isn't called by the panic.  So, we can forget about fbcon, at least (I
hope).


Takashi
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