Re: [PATCH] parisc: avoid WARNING: at kernel/cpu/idle.c:96
From: James Bottomley
Date: Wed May 08 2013 - 17:05:44 EST
On Wed, 2013-05-08 at 22:42 +0200, Helge Deller wrote:
> We need to enable local irqs to avoid this runtime warning.
>
> Signed-off-by: Helge Deller <deller@xxxxxx>
>
> diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
> index 55f92b6..2840d43 100644
> --- a/arch/parisc/kernel/process.c
> +++ b/arch/parisc/kernel/process.c
> @@ -286,3 +286,8 @@ void *dereference_function_descriptor(void *ptr)
> return ptr;
> }
> #endif
> +
> +void arch_cpu_idle(void)
> +{
> + local_irq_enable();
This is definitely wrong. we'd need at least a cpu_relax() in there.
Without that the cpu will bounce around in the idle loop. I'd advise
that we simply keep the default cpu_idle_poll().
However, this looks like a kernel bug to me in cpu_idle_loop()? not
something we should be working around in the arch code.
Thomas, what's going on here? It looks like you can never avoid the
WARN_ON_ONCE if you don't provide any arch specific idle functions. If
you wish to allow this case then the correct patch (keeping the WARN_ON)
would appear to be this one.
James
----
diff --git a/kernel/cpu/idle.c b/kernel/cpu/idle.c
index 8b86c0c..829e41f 100644
--- a/kernel/cpu/idle.c
+++ b/kernel/cpu/idle.c
@@ -56,6 +56,7 @@ void __weak arch_cpu_idle_dead(void) { }
void __weak arch_cpu_idle(void)
{
cpu_idle_force_poll = 1;
+ local_irq_enable();
}
/*
--
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