Re: [PATCH] swsusp: Disable nonboot CPUs before entering platform suspend

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Wednesday, 7 March 2007 22:16, Andrew Morton wrote:
> On Wed, 7 Mar 2007 20:44:11 +0100
> "Rafael J. Wysocki" <rjw@sisk.pl> wrote:
> 
> > From: Rafael J. Wysocki <rjw@sisk.pl>
> > 
> > Prevent the WARN_ON() in arch/x86_64/kernel/acpi/sleep.c:init_low_mapping()
> > from triggering by disabling nonboot CPUs before we finally enter the platform
> > suspend.
> > 
> > Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> > ---
> >  kernel/power/disk.c |    1 +
> >  kernel/power/user.c |    2 +-
> >  2 files changed, 2 insertions(+), 1 deletion(-)
> > 
> > Index: linux-2.6.21-rc2-mm2/kernel/power/disk.c
> > ===================================================================
> > --- linux-2.6.21-rc2-mm2.orig/kernel/power/disk.c
> > +++ linux-2.6.21-rc2-mm2/kernel/power/disk.c
> > @@ -61,6 +61,7 @@ static void power_down(suspend_disk_meth
> >  	switch(mode) {
> >  	case PM_DISK_PLATFORM:
> >  		if (pm_ops && pm_ops->enter) {
> > +			disable_nonboot_cpus();
> >  			kernel_shutdown_prepare(SYSTEM_SUSPEND_DISK);
> >  			pm_ops->enter(PM_SUSPEND_DISK);
> >  			break;
> > Index: linux-2.6.21-rc2-mm2/kernel/power/user.c
> > ===================================================================
> > --- linux-2.6.21-rc2-mm2.orig/kernel/power/user.c
> > +++ linux-2.6.21-rc2-mm2/kernel/power/user.c
> > @@ -398,9 +398,9 @@ static int snapshot_ioctl(struct inode *
> >  
> >  		case PMOPS_ENTER:
> >  			if (data->platform_suspend) {
> > +				disable_nonboot_cpus();
> >  				kernel_shutdown_prepare(SYSTEM_SUSPEND_DISK);
> >  				error = pm_ops->enter(PM_SUSPEND_DISK);
> > -				error = 0;
> >  			}
> >  			break;
> 
> Is this considered 2.6.21 material?  If so why?

Well, the WARN_ON() in arch/x86_64/kernel/acpi/sleep.c:init_low_mapping()
triggers every time an SMP x86_64 box is suspended to disk using the platform
mode (default), which is quite annoying IMHO and users think something wrong is
going on.  This will probably cause them to report the problem and I'd rather
like to avoid handling these reports. ;-)