Messages in this thread | | | Date | Mon, 27 Nov 2023 09:52:35 -0500 | Subject | Re: [PATCH 02/20] x86/mce: Define mce_setup() helpers for global and per-CPU fields | From | Yazen Ghannam <> |
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On 11/22/2023 1:24 PM, Borislav Petkov wrote: > 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? >
Yep, understood. Thanks!
-Yazen
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