2005-01-24 22:02:34

by Kumar Gala

Subject: [PATCH] ppc32: fix powersave with interrupts disabled

It looks like the problem has to do with entering the powersave routine
with irqs disabled. Here is a patch that will only enter powersave if irqs
are enabled.

Entering powersave on PPC while irqs are disabled causes a hang. Only
enter powersave if irqs are disabled.

Signed-off-by: Brian Waite <[email protected]>
Signed-off-by: Kumar Gala <[email protected]>

---
diff -Nru a/arch/ppc/kernel/idle.c b/arch/ppc/kernel/idle.c
--- a/arch/ppc/kernel/idle.c 2005-01-24 15:48:24 -06:00
+++ b/arch/ppc/kernel/idle.c 2005-01-24 15:48:24 -06:00
@@ -39,7 +39,7 @@
powersave = ppc_md.power_save;

if (!need_resched()) {
- if (powersave != NULL)
+ if (powersave != NULL && !irqs_disabled())
powersave();
else {
#ifdef CONFIG_SMP

2005-01-25 02:38:42

by Benjamin Herrenschmidt

Subject: Re: [PATCH] ppc32: fix powersave with interrupts disabled

On Mon, 2005-01-24 at 15:51 -0600, Kumar Gala wrote:
> It looks like the problem has to do with entering the powersave routine
> with irqs disabled. Here is a patch that will only enter powersave if irqs
> are enabled.
>
> Entering powersave on PPC while irqs are disabled causes a hang. Only
> enter powersave if irqs are disabled.

I have a different fix which is to re-enable them (basically to move the
local_irq_disable we do in #ifdef CONFIG_SMP above the whole block,
removing the #else case).

I'm waiting for Ingo's ack about what exact race he's trying to fix
though...

Ben.