Messages in this thread | | | Date | Wed, 22 Nov 2023 19:24:51 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 02/20] x86/mce: Define mce_setup() helpers for global and per-CPU fields |
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On Sat, Nov 18, 2023 at 01:32:30PM -0600, Yazen Ghannam wrote: > +void mce_setup_global(struct mce *m)
We usually call those things "common":
mce_setup_common().
> +{ > + memset(m, 0, sizeof(struct mce)); > + > + m->cpuid = cpuid_eax(1); > + m->cpuvendor = boot_cpu_data.x86_vendor; > + m->mcgcap = __rdmsr(MSR_IA32_MCG_CAP); > + /* need the internal __ version to avoid deadlocks */ > + m->time = __ktime_get_real_seconds(); > +} > + > +void mce_setup_per_cpu(struct mce *m)
And call this
mce_setup_for_cpu(unsigned int cpu, struct mce *m);
so that it doesn't look like some per_cpu helper.
And yes, you should supply the CPU number as an argument. Because otherwise, when you look at your next change:
+ mce_setup_global(&m); + m.cpu = m.extcpu = cpu; + mce_setup_per_cpu(&m);
This contains the "hidden" requirement that m.extcpu happens *always* *before* the mce_setup_per_cpu() call and that is flaky and error prone.
So make that:
mce_setup_common(&m); mce_setup_for_cpu(m.extcpu, &m);
and do m.cpu = m.extcpu = cpu inside the second function.
And then it JustWorks(tm) and you can't "forget" assigning m.extcpu and there's no subtlety.
Ok?
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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