Re: [PATCH v2 06/10] x86/mce: Convert multiple if () statements into a switch() statement

[Dave Hansen]

On 10/21/24 09:06, Luck, Tony wrote:
>>         /*
>>          * All newer Intel systems support MCE broadcasting. Enable
>>          * synchronization with a one second timeout.
>>          */
>> -       if ((c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xe)) &&
>> -           cfg->monarch_timeout < 0)
>> +       if (c->x86_vfm >= INTEL_CORE_YONAH && cfg->monarch_timeout < 0)
>>                 cfg->monarch_timeout = USEC_PER_SEC;
> This change is correct. But the old code makes it more explicit that
> CPUs in families > 6 take this action. As the author of the VFM changes
> it's clear to me, maybe less so to others?
> 
> But maybe its OK.  The comment does help a lot. Anyone else have thoughts on this?

It certainly is a bit subtle.

To me, the earlier check would be even better if it were:

-	if (c->x86 < 6)
+	if (c->x86_vfm < INTEL_PENTIUM_PRO)
		return;

That at least makes it more clear that it's a range of models and avoids
having a ->x86 check mixed with a ->x86_vfm one.