Re: [PATCH] PM: invoke suspend notifications after console switch

[Johannes Berg <johannes@sipsolutions.net>]

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On Thu, 2008-01-24 at 11:46 +1100, Benjamin Herrenschmidt wrote:
> > Its pretty intrusive I'd say. And it is wrong; we'd prefer userspace
> > to know what we are doing; if they are told we are suspending,
> > userspace may be able to do something more clever than long console
> > switch.
> > 
> > I'd prefer this not to go into mainline.
> 
> So you'd prefer mainline to be broken and X to lock up ? nice !
> 
> The console switch happens -anyway- with the current code right ? So we
> aren't changing that.

Mind you, that's the (only!) other alternative: removing the in-kernel
console switch completely which is the only way to allow userspace to do
something "more clever than long console switch".

> However, (even today I believe), users of /dev/apm_bios, such as X, will
> deadlock the VT subsystem if they get notified of the suspend before the
> kernel initiated console switch happen (which can happen today if the
> suspend is triggered by an APM application I -think- (to be verified)

Yeah I'm pretty sure that can happen, but in fact, that will happen
regardless of this patch until my other patch is applied.

johannes

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