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Re: [ACPI] ACPI using smp_processor_id in preemptible code
On Monday 10 January 2005 08:04 pm, Li Shaohua wrote:
> On Mon, 2005-01-10 at 17:55, Pavel Machek wrote:
> > > >I enabled CPU hotplug and preemptible debugging... now I get...
> > > >
> > > >BUG: using smp_processor_id() in preemptible [00000001] code:
> > > >swapper/0
> > > >caller is acpi_processor_idle+0xb/0x235
> > > > [<c020ba28>] smp_processor_id+0xa8/0xc0
> > > > [<c02338ce>] acpi_processor_idle+0xb/0x235
> > > > [<c02338c3>] acpi_processor_idle+0x0/0x235
> > > > [<c02338ce>] acpi_processor_idle+0xb/0x235
> > > > [<c02338c3>] acpi_processor_idle+0x0/0x235
> > > > [<c02338c3>] acpi_processor_idle+0x0/0x235
> > > > [<c02338c3>] acpi_processor_idle+0x0/0x235
> > > > [<c0101115>] cpu_idle+0x75/0x110
> > > > [<c04f5988>] start_kernel+0x158/0x180
> > > > [<c04f5390>] unknown_bootoption+0x0/0x1e0
> > > It doesn't trouble to me. It's in idle thread.
> >
> > You mean it does not happen to you? On my machine it fills logs very
> > quickly...
> What I mean is idle thread can't be migrated so this doesn't impact the
> correctness. I guess the preemptible debugging can't recognise such
> situation.
>
Why don't you just move that statement down, like in the patch below.
Also, if processor is not registered but idle thread managed to call
acpi_processor_idle I think it's BUG()...
I also cut out unnecessary local variable initializations.
Signed-off-by: Dmitry Torokhov <dtor@xxxxxxx>
--
Dmitry
===== drivers/acpi/processor.c 1.72 vs edited =====
--- 1.72/drivers/acpi/processor.c 2004-12-03 02:25:47 -05:00
+++ edited/drivers/acpi/processor.c 2005-01-10 20:58:38 -05:00
@@ -337,15 +337,11 @@
static void
acpi_processor_idle (void)
{
- struct acpi_processor *pr = NULL;
- struct acpi_processor_cx *cx = NULL;
- unsigned int next_state = 0;
- unsigned int sleep_ticks = 0;
- u32 t1, t2 = 0;
-
- pr = processors[smp_processor_id()];
- if (!pr)
- return;
+ struct acpi_processor *pr;
+ struct acpi_processor_cx *cx;
+ unsigned int next_state;
+ unsigned int sleep_ticks;
+ u32 t1, t2;
/*
* Interrupts must be disabled during bus mastering calculations and
@@ -361,6 +357,10 @@
local_irq_enable();
return;
}
+
+ pr = processors[smp_processor_id()];
+ if (!pr)
+ BUG();
cx = &(pr->power.states[pr->power.state]);
-
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