Re: [PATCH v1] x86/platform/intel-mid: Revert "Make 'bt_sfi_data' const"

From: Ingo Molnar
Date: Thu Dec 28 2017 - 07:53:52 EST



* Julia Lawall <julia.lawall@xxxxxxx> wrote:

> > > [...] There does seem to be a few cases where the field actually does hold an
> > > integer. I guess this is not a problem?
> >
> > Could you point to such an example?
>
> drivers/thermal/intel_soc_dts_thermal.c:#define BYT_SOC_DTS_APIC_IRQ 86
>
> and then:
>
> static const struct x86_cpu_id soc_thermal_ids[] = {
> { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_SILVERMONT1, 0,
> BYT_SOC_DTS_APIC_IRQ},
> {}
> };
>
> and finally:
>
> soc_dts_thres_irq = (int)match_cpu->driver_data;
>
> Also:
>
> arch/x86/kernel/apic/apic.c
>
> #define DEADLINE_MODEL_MATCH_REV(model, rev) \
> { X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, (unsigned long)rev
> }
>
> DEADLINE_MODEL_MATCH_REV ( INTEL_FAM6_BROADWELL_X, 0x0b000020),
> DEADLINE_MODEL_MATCH_REV ( INTEL_FAM6_HASWELL_CORE, 0x22),
> etc. (all 2-digit numbers in the remaining case).

Ok - I think in these cases the resulting long->pointer type conversion is a _lot_
less dangerous than the pointer->long conversion which caused the regression.

So unless the resulting code is excessively ugly, this feels like the right
approach to me.

Thanks,

Ingo