Re: [Qemu-devel] [PATCH 02/20] target-i386: convert 'hv_spinlocks' to static property

["Andreas Färber" <afaerber@suse.de>]

Am 16.07.2013 00:25, schrieb Igor Mammedov:
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---
> v2:
>  - rebase on top of hyperv_spinlock_attempts in X86CPU
> ---
>  target-i386/cpu.c | 48 +++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 47 insertions(+), 1 deletion(-)
> 
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 14e9c7e..00c2882 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -1473,6 +1473,49 @@ static void x86_cpu_get_feature_words(Object *obj, Visitor *v, void *opaque,
>      error_propagate(errp, err);
>  }
>  
> +static void x86_get_hv_spinlocks(Object *obj, Visitor *v, void *opaque,
> +                                 const char *name, Error **errp)
> +{
> +    X86CPU *cpu = X86_CPU(obj);
> +    int64_t value = cpu->hyperv_spinlock_attempts;
> +
> +    visit_type_int(v, &value, name, errp);
> +}
> +
> +static void x86_set_hv_spinlocks(Object *obj, Visitor *v, void *opaque,
> +                                 const char *name, Error **errp)
> +{
> +    const int64_t min = 0xFFF;
> +    const int64_t max = UINT_MAX;
> +    X86CPU *cpu = X86_CPU(obj);
> +    int64_t value;
> +
> +    visit_type_int(v, &value, name, errp);
> +    if (error_is_set(errp)) {
> +        return;
> +    }

errp may be NULL. And if an Error gets raised here but not set to *errp
for lack of pointer, value might be uninitialized:
object_property_parse(obj, "not-a-number", "hv-spinlocks", NULL);
So we cannot rely on error_is_set(errp) but must use a local variable to
enforce any return. Fixed on qom-cpu-next as follows:

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 435b3b9..0a5a4f0 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -1611,10 +1611,12 @@ static void x86_set_hv_spinlocks(Object *obj,
Visitor *v, void *opaque,
     const int64_t min = 0xFFF;
     const int64_t max = UINT_MAX;
     X86CPU *cpu = X86_CPU(obj);
+    Error *err = NULL;
     int64_t value;

-    visit_type_int(v, &value, name, errp);
-    if (error_is_set(errp)) {
+    visit_type_int(v, &value, name, &err);
+    if (err) {
+        error_propagate(errp, err);
         return;
     }


https://github.com/afaerber/qemu-cpu/commits/qom-cpu-next

Regards,
Andreas


> +
> +    if (value < min || value > max) {
> +        error_setg(errp, "Property %s.%s doesn't take value %" PRId64
> +                  " (minimum: %" PRId64 ", maximum: %" PRId64 ")",
> +                  object_get_typename(obj), name ? name : "null",
> +                  value, min, max);
> +        return;
> +    }
> +    cpu->hyperv_spinlock_attempts = value;
> +}
> +
> +static PropertyInfo qdev_prop_spinlocks = {
> +    .name  = "int",
> +    .get   = x86_get_hv_spinlocks,
> +    .set   = x86_set_hv_spinlocks,
> +};
> +
> +static Property cpu_x86_properties[] = {
> +    { .name  = "hv-spinlocks", .info  = &qdev_prop_spinlocks },
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
>  static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *name)
>  {
>      x86_def_t *def;
> @@ -1586,6 +1629,7 @@ static void cpu_x86_parse_featurestr(X86CPU *cpu, char *features, Error **errp)
>              } else if (!strcmp(featurestr, "hv-spinlocks")) {
>                  char *err;
>                  const int min = 0xFFF;
> +                char num[32];
>                  numvalue = strtoul(val, &err, 0);
>                  if (!*val || *err) {
>                      error_setg(errp, "bad numerical value %s", val);
> @@ -1597,7 +1641,8 @@ static void cpu_x86_parse_featurestr(X86CPU *cpu, char *features, Error **errp)
>                              min);
>                      numvalue = min;
>                  }
> -                cpu->hyperv_spinlock_attempts = numvalue;
> +                snprintf(num, sizeof(num), "%" PRId32, numvalue);
> +                object_property_parse(OBJECT(cpu), num, featurestr, errp);
>              } else {
>                  error_setg(errp, "unrecognized feature %s", featurestr);
>                  goto out;
> @@ -2521,6 +2566,7 @@ static void x86_cpu_common_class_init(ObjectClass *oc, void *data)
>      xcc->parent_realize = dc->realize;
>      dc->realize = x86_cpu_realizefn;
>      dc->bus_type = TYPE_ICC_BUS;
> +    dc->props = cpu_x86_properties;
>  
>      xcc->parent_reset = cc->reset;
>      cc->reset = x86_cpu_reset;

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