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.
Linus
