Re: [Xen-devel] [PATCH v4 3/6] smp: add function to execute a function synchronously on a cpu

[Peter Zijlstra <peterz@xxxxxxxxxxxxx>]

On Tue, Apr 05, 2016 at 07:10:04AM +0200, Juergen Gross wrote:
> +int smp_call_on_cpu(unsigned int cpu, bool pin, int (*func)(void *), void 
> *par)

Why .pin and not .phys? .pin does not (to me) reflect the
hypervisor/physical-cpu thing.

Also, as per smp_call_function_single() would it not be more consistent
to make this the last argument?

> +{
> +     struct smp_call_on_cpu_struct sscs = {
> +             .work = __WORK_INITIALIZER(sscs.work, smp_call_on_cpu_callback),
> +             .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
> +             .func = func,
> +             .data = par,
> +             .cpu  = pin ? cpu : -1,
> +     };
> +
> +     if (cpu >= nr_cpu_ids)

You might want to also include cpu_online().

        if (cpu >= nr_cpu_ids || !cpu_online(cpu))
> +             return -ENXIO;

Seeing how its fairly hard to schedule work on a cpu that's not actually
there.

> +
> +     queue_work_on(cpu, system_wq, &sscs.work);
> +     wait_for_completion(&sscs.done);
> +
> +     return sscs.ret;
> +}



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