Re: [Qemu-devel] [PATCH 03/11] pc: extract CPU lookup into a separate function

[Eduardo Habkost]

On Thu, Jun 23, 2016 at 04:54:21PM +0200, Igor Mammedov wrote:
> it will be reused in the next patch at pre_plug time
> 
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
>  hw/i386/pc.c | 24 +++++++++++++++++-------
>  1 file changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 07a3b82..ec9b14b 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1675,11 +1675,25 @@ static int pc_apic_cmp(const void *a, const void *b)
>     return apic_a->arch_id - apic_b->arch_id;
>  }
>  
> +static CPUArchId *pc_find_cpu(PCMachineState *pcms, CPUState *cpu, int *idx)

A short comment explaining what it does (and what does the return
value actually means) would't be bad.

The function name confused me when reviewing patch 07/11, as:
1) returning non-NULL means a CPU "slot"[1] exists, not
necessarily that a CPU exists; 2) returning NULL means that a CPU
doesn't exist _and_ that the ID/slot is not available for
plugging.

I would call it pc_find_cpu_slot() or pc_find_possible_cpu_id().

[1] Or whatever name we choose to call a "possible ID/address for
    a CPU".


> +{
> +    CPUClass *cc = CPU_GET_CLASS(cpu);
> +    CPUArchId apic_id, *found_cpu;
> +
> +    apic_id.arch_id = cc->get_arch_id(CPU(cpu));
> +    found_cpu = bsearch(&apic_id, pcms->possible_cpus->cpus,
> +        pcms->possible_cpus->len, sizeof(*pcms->possible_cpus->cpus),
> +        pc_apic_cmp);
> +    if (found_cpu && idx) {
> +        *idx = found_cpu - pcms->possible_cpus->cpus;
> +    }
> +    return found_cpu;
> +}
> +
>  static void pc_cpu_plug(HotplugHandler *hotplug_dev,
>                          DeviceState *dev, Error **errp)
>  {
> -    CPUClass *cc = CPU_GET_CLASS(dev);
> -    CPUArchId apic_id, *found_cpu;
> +    CPUArchId *found_cpu;
>      HotplugHandlerClass *hhc;
>      Error *local_err = NULL;
>      PCMachineState *pcms = PC_MACHINE(hotplug_dev);
> @@ -1703,11 +1717,7 @@ static void pc_cpu_plug(HotplugHandler *hotplug_dev,
>      /* increment the number of CPUs */
>      rtc_set_memory(pcms->rtc, 0x5f, rtc_get_memory(pcms->rtc, 0x5f) + 1);
>  
> -    apic_id.arch_id = cc->get_arch_id(CPU(dev));
> -    found_cpu = bsearch(&apic_id, pcms->possible_cpus->cpus,
> -        pcms->possible_cpus->len, sizeof(*pcms->possible_cpus->cpus),
> -        pc_apic_cmp);
> -    assert(found_cpu);
> +    found_cpu = pc_find_cpu(pcms, CPU(dev), NULL);
>      found_cpu->cpu = CPU(dev);
>  out:
>      error_propagate(errp, local_err);
> -- 
> 1.8.3.1
> 

-- 
Eduardo