Messages in this thread | | | Date | Tue, 19 Sep 2023 11:24:41 +0100 | From | "Russell King (Oracle)" <> | Subject | Re: [RFC PATCH v2 32/35] ACPI: add support to register CPUs based on the _STA enabled bit |
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On Thu, Sep 14, 2023 at 05:13:41PM +0100, Jonathan Cameron wrote: > On Wed, 13 Sep 2023 16:38:20 +0000 > James Morse <james.morse@arm.com> wrote: > > +static int acpi_processor_make_enabled(struct acpi_processor *pr) > > +{ > > + unsigned long long sta; > > + acpi_status status; > > + bool present, enabled; > > + > > + if (!acpi_has_method(pr->handle, "_STA")) > > + return arch_register_cpu(pr->id); > > + > > + status = acpi_evaluate_integer(pr->handle, "_STA", NULL, &sta); > > + if (ACPI_FAILURE(status)) > > + return -ENODEV; > > + > > + present = sta & ACPI_STA_DEVICE_PRESENT; > > + enabled = sta & ACPI_STA_DEVICE_ENABLED; > > + > > + if (cpu_online(pr->id) && (!present || !enabled)) { > > + pr_err_once(FW_BUG "CPU %u is online, but described as not present or disabled!\n", pr->id); > > Why once? If this for some reason happened on multiple CPUs I think we'd want to know. > > > + add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK); > > + } else if (!present || !enabled) { > > + return -ENODEV; > > + } > > I guess you didn't do a nested if here to avoid even longer lines. > Could flip things around though I don't like this much either as it makes > the normal good path exit mid way down. > > if (present && enabled) > return arch_register_cpu(pr->id); > > if (!cpu_online(pr->id)) > return -ENODEV; > > pr_err... > add_taint(... > > return arch_register_cpu(pr->id); > > Ah well. Some code just has to be less than pretty.
How about:
static int acpi_processor_should_register_cpu(struct acpi_processor *pr) { unsigned long long sta; acpi_status status;
if (!acpi_has_method(pr->handle, "_STA")) return 0;
status = acpi_evaluate_integer(pr->handle, "_STA", NULL, &sta); if (ACPI_FAILURE(status)) return -ENODEV;
if (sta & ACPI_STA_DEVICE_PRESENT && sta & ACPI_STA_DEVICE_ENABLED) return 0;
if (cpu_online(pr->id)) { pr_err_once(FW_BUG "CPU %u is online, but described as not present or disabled!\n", pr->id);
/* Register the CPU anyway */ return 0; }
return -ENODEV; }
static int acpi_processor_make_enabled(struct acpi_processor *pr) { int ret = acpi_processor_should_register_cpu(pr);
if (ret) return ret;
return arch_register_cpu(pr->id); }
I would keep the "cpu online but !present and !disabled" as a sub-block because it makes better reading flow, but instead break the message as I've indicated above.
-- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
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