Re: [Qemu-devel] [PATCH 08/16] cpu: add helper cpu_exists(), to check if CPU with specified id exists

[Igor Mammedov]

On Mon, 22 Apr 2013 13:28:12 +0300
"Michael S. Tsirkin" <address@hidden> wrote:

> On Tue, Apr 16, 2013 at 12:12:48AM +0200, Igor Mammedov wrote:
> > ... it should be used only on slow path since it does recursive search
> >     on /machine QOM tree for objects of TYPE_CPU
> > 
> > Signed-off-by: Igor Mammedov <address@hidden>
> > Reviewed-by: Paolo Bonzini <address@hidden>
> 
> I would prefer qemu_for_each_cpu, that is also useful for ACPI.  And do
> we need to scan all QOM?  This will take a while to repeat if there are
> many devices.
> How about the below? You can add a wrapper that sets
> a bit if CPU exists.
qemu_for_each_cpu looks usefull, it could replace a lot of place that do
open-coded exactly this operation and hide open-codded access to next_cpu
pointer. 

I can easily change to using it, and take it this patch into this series.

> 
> 
> commit 4ff1332ff56069574f450bb44819156bd91bd105
> Author: Michael S. Tsirkin <address@hidden>
> Date:   Sun Apr 21 15:44:47 2013 +0300
> 
>     exec: add qemu_for_each_cpu
>     
>     Will be used by ACPI table generation.
>     
>     Signed-off-by: Michael S. Tsirkin <address@hidden>
> 
> diff --git a/exec.c b/exec.c
> index fa1e0c3..2b44cbe 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -265,6 +265,19 @@ CPUState *qemu_get_cpu(int index)
>      return env ? cpu : NULL;
>  }
>  
> +void qemu_for_each_cpu( void (*func)( CPUState *c, void *arg), void *arg)
> +{
> +    CPUArchState *env = first_cpu;
> +    CPUState *cpu;
> +
> +    while (env) {
> +        cpu = ENV_GET_CPU(env);
> +        func(cpu, arg);
> +        env = env->next_cpu;
> +    }
> +}
> +
> +
>  void cpu_exec_init(CPUArchState *env)
>  {
>      CPUState *cpu = ENV_GET_CPU(env);
> diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> index 3664a1b..db857e3 100644
> --- a/include/qom/cpu.h
> +++ b/include/qom/cpu.h
> @@ -223,6 +223,8 @@ void run_on_cpu(CPUState *cpu, void (*func)(void
> *data), void *data); */
>  CPUState *qemu_get_cpu(int index);
>  
> +void qemu_for_each_cpu( void (*func)( CPUState *c, void *arg), void *arg);
> +
>  #ifndef CONFIG_USER_ONLY
>  
>  typedef void (*CPUInterruptHandler)(CPUState *, int);
>