Re: 3.2-rc2+: Reported regressions from 3.0 and 3.1

On Tue, Nov 29, 2011 at 07:34:28PM +0100, Borislav Petkov wrote:

On Tue, Nov 29, 2011 at 01:04:14PM -0500, Konrad Rzeszutek Wilk wrote:

quoted

This patch:

commit d91ee5863b71e8c90eaf6035bff3078a85e2e7b5
Author: Len Brown [off-list ref]
Date:   Fri Apr 1 18:28:35 2011 -0400

    cpuidle: replace xen access to x86 pm_idle and default_idle

    ..scribble on pm_idle and access default_idle,
   have it simply disable_cpuidle() so acpi_idle will not load and
   architecture default HLT will be used.

idea was to have one call - disable_cpuidle() which would make
pm_idle not be molested by other code. It disallows cpuidle_idle_call
and acpi_idle_call to not set pm_idle (which is excellent). But the

what is acpi_idle_call, I can't find it anywhere.

You are right. I had "acpi_idle_enter_*" and its friend in mind. Which
are called from the cpuidle_idle_call.

Let me fix that comment up.

quoted

amd_e400_idle and mwait_idle can still setup pm_idle which we really
do not want.

This is not the case: rather select_idle_routine()/idle_setup() sets
pm_idle.

Yes. Let me fix up the comment.

[..]

quoted

+bool set_pm_idle_to_default()
+{
+	if (!pm_idle) {
+		pm_idle = default_idle;
+		return true;
+	}
+	return false;
+}

I don't understand what you're trying to achieve here? Do you want
default_idle to be always the pm_idle for xen or what is the deal here?

Yes (always want default_idle).

If yes, then simply do:

bool set_pm_idle_to_default(void)	// remember to add "void" for no function args
{
	bool ret = !!pm_idle;

	pm_idle = default_idle;

That would work too.

	return ret;

}

...

quoted

 void stop_this_cpu(void *dummy) 
 {
 	local_irq_disable();

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 46d6d21..7506181 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c

@@ -448,6 +448,6 @@ void __init xen_arch_setup(void)
 #endif
 	disable_cpuidle();
 	boot_option_idle_override = IDLE_HALT;
-
+	WARN_ON(!set_pm_idle_to_default());

and then do

	WARN_ON(set_pm_idle_to_default());

instead of having arbitrary confusing logic. This way you can warn
whether something else set pm_idle already. Or?

That would work as well.