linux-kernel - Re: BUG: using smp_processor_id() during suspend with 2.6.25-rc8

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Message-ID: <20080411105445.GB18770@elf.ucw.cz>
Date:	Fri, 11 Apr 2008 12:54:45 +0200
From:	Pavel Machek <pavel@....cz>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Jiri Kosina <jkosina@...e.cz>, "Rafael J. Wysocki" <rjw@...k.pl>,
	Andi Kleen <andi@...stfloor.org>,
	Zdenek Kabelac <zdenek.kabelac@...il.com>,
	Kernel development list <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: BUG: using smp_processor_id() during suspend with 2.6.25-rc8

On Fri 2008-04-11 12:51:09, Ingo Molnar wrote:
> 
> * Pavel Machek <pavel@....cz> wrote:
> 
> > diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c
> > index 6c90fb9..8195c37 100644
> > --- a/lib/smp_processor_id.c
> > +++ b/lib/smp_processor_id.c
> > @@ -35,6 +35,13 @@ unsigned int debug_smp_processor_id(void
> >  		goto out;
> >  
> >  	/*
> > +	 * It is valid to assume CPU-locality if there's just one
> > +	 * CPU active
> > +	 */
> > +	if (num_online_cpus() == 1)
> > +		goto out;
> 
> thanks Pavel, i picked this up into sched-devel.git - it makes sense 
> independently of whether it solves the warning.

Thanks!

(I just want to fix the underlying problem in suspend, too. I guess
I'll just do something like

diff --git a/drivers/base/sys.c b/drivers/base/sys.c
index 8e13fd9..adb7850 100644
--- a/drivers/base/sys.c
+++ b/drivers/base/sys.c
@@ -367,6 +367,7 @@ int sysdev_suspend(pm_message_t state)
 			/* Call auxillary drivers first */
 			list_for_each_entry(drv, &cls->drivers, entry) {
 				if (drv->suspend) {
+					BUG_ON(!in_interrupt());
 					ret = drv->suspend(sysdev, state);
 					if (ret)
 						goto aux_driver;
@@ -442,6 +443,7 @@ int sysdev_resume(void)
 		list_for_each_entry(sysdev, &cls->kset.list, kobj.entry) {
 			pr_debug(" %s\n", kobject_name(&sysdev->kobj));
 
+			BUG_ON(!in_interrupt());
 			__sysdev_resume(sysdev);
 		}
 	}

...to catch this kind of problems early).
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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