Re: [Qemu-devel] [PATCH 2/6] cpu: make cpu_generic_init() abort QEMU on error

[Thomas Huth]

On 04.09.2017 16:00, Igor Mammedov wrote:
> Almost every user of cpu_generic_init() checks for
> returned NULL and then reports failure in a custom way
> and aborts process.
> Some users assume that call can't fail and don't check
> for failure, though they should have checked for it.
> 
> In either cases cpu_generic_init() failure is fatal,
> so instead of checking for failure and reporting
> it various ways, make cpu_generic_init() report
> errors in consistent way and terminate QEMU on failure.
> 
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
> Even though it's tree wide change, it's trivial so all
> affected call sites are included within one patch.
[...]
> diff --git a/qom/cpu.c b/qom/cpu.c
> index d715890..307d638 100644
> --- a/qom/cpu.c
> +++ b/qom/cpu.c
> @@ -61,7 +61,7 @@ CPUState *cpu_create(const char *typename)
>      if (err != NULL) {
>          error_report_err(err);
>          object_unref(OBJECT(cpu));
> -        return NULL;
> +        exit(EXIT_FAILURE);
>      }
>      return cpu;
>  }
> @@ -78,8 +78,9 @@ const char *cpu_parse_features(const char *typename, const 
> char *cpu_model)
>  
>      oc = cpu_class_by_name(typename, model_pieces[0]);
>      if (oc == NULL) {
> +        error_report("unable to find CPU model '%s'", model_pieces[0]);
>          g_strfreev(model_pieces);
> -        return NULL;
> +        exit(EXIT_FAILURE);
>      }
>  
>      cpu_type = object_class_get_name(oc);
> @@ -88,7 +89,7 @@ const char *cpu_parse_features(const char *typename, const 
> char *cpu_model)
>      g_strfreev(model_pieces);
>      if (err != NULL) {
>          error_report_err(err);
> -        return NULL;
> +        exit(EXIT_FAILURE);
>      }
>      return cpu_type;
>  }
> @@ -100,10 +101,8 @@ CPUState *cpu_generic_init(const char *typename, const 
> char *cpu_model)
>       */
>      const char *cpu_type = cpu_parse_features(typename, cpu_model);
>  
> -    if (cpu_type) {
> -        return cpu_create(cpu_type);
> -    }
> -    return NULL;
> +    assert(cpu_type);
> +    return cpu_create(cpu_type);
>  }

Not sure, but wouldn't it be better to do the error reporting and exit
in cpu_generic_init() instead? In case we ever might want to re-use the
create and parse_feature functions for device_add later (?), and then
the functions must not exit directly anymore...

 Thomas