On Tue, Apr 27 2021 at 10:00, Linus Torvalds wrote:
> On Mon, Apr 26, 2021 at 11:37 PM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>>
>> > > 354 if (this_cpu_read(cpu_info.smt_active)) {
>>
>> That's a valid construct and the kernel of full of percpuvar.member reads/writes.
>
> Hmm. "cpu_info" doesn't seem to be marked as a percpu data structure.
>
> Is this perhaps a UP config? Because we have:
>
> extern struct cpuinfo_x86 boot_cpu_data;
> ...
> #ifdef CONFIG_SMP
> DECLARE_PER_CPU_READ_MOSTLY(struct cpuinfo_x86, cpu_info);
> #define cpu_data(cpu) per_cpu(cpu_info, cpu)
> #else
> #define cpu_info boot_cpu_data
> #define cpu_data(cpu) boot_cpu_data
> #endif
>
> and notice how if CONFIG_SMP isn't set, 'cpu_info' just turns into a
> regular non-percpu thing.
>
> But the sparse checking doesn't go away just because it's compiled for UP.
Duh yes. I'm a moron.
