linux-kernel - Re: PCI PM: Restore standard config registers of all devices early

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Message-ID: <20090210202524.GF1382@ucw.cz>
Date:	Tue, 10 Feb 2009 21:25:24 +0100
From:	Pavel Machek <pavel@...e.cz>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jesse Barnes <jesse.barnes@...el.com>,
	Andreas Schwab <schwab@...e.de>, Len Brown <lenb@...nel.org>
Subject: Re: PCI PM: Restore standard config registers of all devices early

Hi!

> > I'll have a look at the ACPI thing.
> 
> Generally speaking, we'd need to run acpi_evaluate_object() with interrupts
> off.
> 
> There are two apparent problems with that, from a quick look:
> 
> * The ACPI_MTX_INTERPRETER mutex needs to be acquired, but we know we won't
>   need that mutex with interrupts off, so presumably we can work around this.

In such case we either need refrigerator, or we should grab
MTX_INTERPRETER before we start suspending, hmm.

> * Memory allocations with GFP_KERNEL are made, which is even worse, because
>   we really shouldn't do that during suspend _at_ _all_, even during the regular
>   ->suspend() with interrupts on, because there's not guarantee that swap will
>   will be available at that time.  So, for the sake of correctness, we should
>   get rid of the GFP_KERNEL from the ACPI code paths executed during
>   suspend-resume anyway.

Well, we have some small reserves for stuff like that...
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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