linux-kernel - Re: [PATCH]: In kernel hibernation, suspend to both

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Date:	Sat, 12 May 2012 23:47:08 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Bojan Smojver <bojan@...ursive.com>
Cc:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	Linux PM list <linux-pm@...r.kernel.org>,
	linux-kernel@...r.kernel.org, bp@...en8.de
Subject: Re: [PATCH]: In kernel hibernation, suspend to both

On Wednesday, May 09, 2012, Bojan Smojver wrote:
> On Wed, 2012-05-09 at 13:40 +0530, Srivatsa S. Bhat wrote:
> > > +             error = suspend_devices_and_enter(PM_SUSPEND_MEM);
> > 
> > 
> > I can imagine running into a host of problems here, since the suspend
> > sequence is not carried out fully, from the beginning.
> > 
> > For example, this will skip sending out the PM_SUSPEND_PREPARE and the
> > PM_POST_SUSPEND notifiers. Worse, we actually send out the
> > PM_HIBERNATION_PREPARE
> > and PM_POST_HIBERNATION notifiers and then do a suspend instead,
> > underneath!
> > 
> > (Similar cases for the rest of the notifiers sent during suspend vs
> > hibernation).
> > 
> > Don't we need to handle such things properly, in order to make
> > suspend-to-both
> > work reliably? 
> 
> Honest answer - I have absolutely no idea. I've seen the code of
> suspend-utils (i.e. user mode stuff) and it seems to me that it does
> exactly this. Could be wrong of course, just like many times before.
> 
> Rafael?

Sorry, that has fallen out of my radar somehow.

Srivatsa is right, we should generally pay attention to those details.

I think we should generally use a different "prepare" notification for the
save-image-and-suspend case.

Thanks,
Rafael
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