Re: [patch 2/2] x86: mce: Implement cmci poll mode for intelmachines

[Thomas Gleixner]

On Wed, 6 Jun 2012, Chen Gong wrote:
> ä 2012/6/6 18:23, Thomas Gleixner åé:
> I think you mean
> 
> -               del_timer_sync(t);
>                 smp_call_function_single(cpu, mce_disable_cpu, &action, 1);
> +		del_timer_sync(t);
>                 break;

No I meant it the way I wrote, but as you don't execute hotplug it's
irrelevant.

So the obvious candidate is the mce-injection code, which was
obviously never tested with DEBUG_PREEMPT enabled.

raise_local() can be called with preemption enabled from
raise_mce(). Fix for that below.

Though I can't see how that would do anything with the timer.

Another thing in that mce injection code is that there is no
protection against concurrent writes, except when the device was
opened with O_EXCL, but what guarantees that ?

Thanks,

	tglx

Index: tip/arch/x86/kernel/cpu/mcheck/mce-inject.c
===================================================================
--- tip.orig/arch/x86/kernel/cpu/mcheck/mce-inject.c
+++ tip/arch/x86/kernel/cpu/mcheck/mce-inject.c
@@ -194,7 +194,11 @@ static void raise_mce(struct mce *m)
 		put_online_cpus();
 	} else
 #endif
+	{
+		preempt_disable();
 		raise_local();
+		preempt_enable();
+	}
 }
 
 /* Error injection interface */