linux-kernel - Re: [PATCH 3/7] PCI PM: Fix saving of device state in pci_legacy

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Message-Id: <1233806770.4612.68.camel@pasglop>
Date:	Thu, 05 Feb 2009 15:06:10 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	michael@...erman.id.au
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Frans Pop <elendil@...net.nl>, rjw@...k.pl,
	jbarnes@...tuousgeek.org, linux-pm@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH 3/7] PCI PM: Fix saving of device state in
 pci_legacy_suspend


> Well I'm glad you listened to me when I told you not to fire off a rant
> email before I had another look at it ;)
> 
> Because Arjan has patched the generic bug.h so that we at least get the
> printk on powerpc, and then use our version of __WARN().

Right. A deep breath later or two ... the current upstream code in
pci-driver.c doesn't have a message, which is why I didn't see it. The
-new- code from Rafael does, and it would work thanks to Arjan fix. Now
I should indeed stop listening to you telling me it's broken before I
get a chance to verify it :-)

> As far as the code gen, with gcc 4.3.1 (debian).

 .../...

> So it's jumping over the if body, rather than moving it out of the
> straight line. It is hinting it right, so we should check if that helps
> us at all.

Right, gcc is full of sh*t as usual. Now try replacing the magic trap
which we still use in there, with a normal C function call (ie branch
out of line), see if it makes a difference. The trap statement uses an
inline asm statement and I know for a fact that the mere existence of
such a thing will make gcc already dubious idea of whether to go out of
line or not completely bonkers.

Cheers,
Ben.


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