linux-kernel - Re: [PATCH -v4] x86: MCE: Re-implement MCE log ring buffer as per-CPU ring buffer

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Date:	Mon, 08 Jun 2009 12:09:57 +0900
From:	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
To:	Huang Ying <ying.huang@...el.com>
CC:	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andi Kleen <ak@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -v4] x86: MCE: Re-implement MCE log ring buffer as per-CPU
 ring buffer

Huang Ying wrote:
> Emm, it seem hard to analyze mce_log_cpu from per_cpu_var(mce_log_cpus),
> how about following method:
> 
> struct mce_log {
>     char signature[12];
>     ...
>     struct mce_log_cpu *mcelog_cpus[];
> };
> 
> void mcelog_init(void)
> {
>     int cpu;
>     mcelog.mcelog_cpus = kmalloc(sizeof(void *) * num_possible_cpus();
>     for_each_possible_cpu(cpu)
> 	mcelog.mcelog_cpus[cpu] = &per_cpu(mce_log_cpus, cpu);
> }

It would be good.  Using kzalloc() will be better.
It might be a bit much, but how about adding:

+	mcelog.nr_mcelog_cpus = num_possible_cpus();

Be careful that mcheck_init(), caller of mcelog_init(), will be called
for each booted CPU.  You will need:

+	if (mcelog.mcelog_cpus)
+		return;


Thanks,
H.Seto

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