Re: [Qemu-devel] [RFC PATCH v1 01/10] exec: Remove cpu from cpus list during cpu_exec_exit()

[Thomas Huth]

On 04.03.2016 07:54, Bharata B Rao wrote:
> CPUState *cpu gets added to the cpus list during cpu_exec_init(). It
> should be removed from cpu_exec_exit().
> 
> cpu_exec_init() is called from generic CPU::instance_finalize and some

s/cpu_exec_init/cpu_exec_exit/

> archs like PowerPC call it from CPU unrealizefn. So ensure that we
> dequeue the cpu only once.
> 
> Now -1 value for cpu->cpu_index indicates that we have already dequeued
> the cpu for CONFIG_USER_ONLY case also.
> 
> Signed-off-by: Bharata B Rao <address@hidden>
> ---
>  exec.c | 32 ++++++++++++++++++++++++--------
>  1 file changed, 24 insertions(+), 8 deletions(-)
> 
> diff --git a/exec.c b/exec.c
> index c62c439..7c3f747 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -588,15 +588,9 @@ static int cpu_get_free_index(Error **errp)
>      return cpu;
>  }
>  
> -void cpu_exec_exit(CPUState *cpu)
> +static void cpu_release_index(CPUState *cpu)
>  {
> -    if (cpu->cpu_index == -1) {
> -        /* cpu_index was never allocated by this @cpu or was already freed. 
> */
> -        return;
> -    }
> -
>      bitmap_clear(cpu_index_map, cpu->cpu_index, 1);
> -    cpu->cpu_index = -1;
>  }
>  #else
>  
> @@ -611,11 +605,33 @@ static int cpu_get_free_index(Error **errp)
>      return cpu_index;
>  }
>  
> -void cpu_exec_exit(CPUState *cpu)
> +static void cpu_release_index(CPUState *cpu)
>  {
> +    return;

You could also simply leave that return statement away, I think.

>  }
>  #endif
>  
> +void cpu_exec_exit(CPUState *cpu)
> +{
> +#if defined(CONFIG_USER_ONLY)
> +    cpu_list_lock();
> +#endif
> +    if (cpu->cpu_index == -1) {
> +        /* cpu_index was never allocated by this @cpu or was already freed. 
> */
> +#if defined(CONFIG_USER_ONLY)
> +        cpu_list_unlock();
> +#endif
> +        return;
> +    }
> +
> +    QTAILQ_REMOVE(&cpus, cpu, node);
> +    cpu_release_index(cpu);
> +    cpu->cpu_index = -1;
> +#if defined(CONFIG_USER_ONLY)
> +    cpu_list_unlock();
> +#endif
> +}

Since there are a couple of these

#if defined(CONFIG_USER_ONLY)
    cpu_list_[un]lock();
#endif

in exec.c already, it might be somewhat nices to declare them at the
beginning of the file as empty functions, somewhat like:

#if !defined(CONFIG_USER_ONLY)
static inline void cpu_list_lock(void)
{
}
static inline void cpu_list_unlock(void)
{
}
#endif

What do you think about that?

Apart from that, the patch looks fine to me.

 Thomas