Re: [Qemu-devel] [PATCH 2/7] qom: handle registration of new types when initializing the first ones

[Andreas Färber]

Am 02.05.2013 22:08, schrieb Hervé Poussineau:
> When initializing all types in object_class_foreach, called by 
> object_class_get_list,
> some new types may be registered. Those will change the type internal 
> hashtable which
> is currently enumerated, and may crash QEMU.
> 
> Fix it, by adding a second hash table which contains all the non-initialized 
> types,
> merged to the main one before each round of initializations.
> 
> Bug has been detected when registering dynamic types containing an interface.
> 
> Signed-off-by: Hervé Poussineau <address@hidden>
> ---
>  qom/object.c |   45 +++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 37 insertions(+), 8 deletions(-)

Could you be more specific about how to reproduce the problem? Is it a
generic issue or specific to some later patch in this series? I find
neither object_class_get_list() nor object_class_for_each() being used
in this series. And registering types during object_class_for_each()
doesn't sound right... CC'ing Anthony and Paolo.

Andreas

> diff --git a/qom/object.c b/qom/object.c
> index 75e6aac..e0a24dc 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -65,25 +65,39 @@ struct TypeImpl
>  
>  static Type type_interface;
>  
> +static GHashTable *type_table_to_initialize;
> +static GHashTable *type_table_initialized;
> +
>  static GHashTable *type_table_get(void)
>  {
> -    static GHashTable *type_table;
> -
> -    if (type_table == NULL) {
> -        type_table = g_hash_table_new(g_str_hash, g_str_equal);
> +    if (!type_table_initialized) {
> +        type_table_initialized = g_hash_table_new(g_str_hash, g_str_equal);
>      }
>  
> -    return type_table;
> +    return type_table_initialized;
>  }
>  
>  static void type_table_add(TypeImpl *ti)
>  {
> -    g_hash_table_insert(type_table_get(), (void *)ti->name, ti);
> +    GHashTable **type_table;
> +    if (ti->class) {
> +        type_table = &type_table_initialized;
> +    } else {
> +        type_table = &type_table_to_initialize;
> +    }
> +    if (!*type_table) {
> +        *type_table = g_hash_table_new(g_str_hash, g_str_equal);
> +    }
> +    g_hash_table_insert(*type_table, (void *)ti->name, ti);
>  }
>  
>  static TypeImpl *type_table_lookup(const char *name)
>  {
> -    return g_hash_table_lookup(type_table_get(), name);
> +    TypeImpl *ret = g_hash_table_lookup(type_table_get(), name);
> +    if (!ret && type_table_to_initialize) {
> +        ret = g_hash_table_lookup(type_table_to_initialize, name);
> +    }
> +    return ret;
>  }
>  
>  static TypeImpl *type_register_internal(const TypeInfo *info)
> @@ -573,13 +587,28 @@ static void object_class_foreach_tramp(gpointer key, 
> gpointer value,
>      data->fn(k, data->opaque);
>  }
>  
> +static void object_class_merge(gpointer key, gpointer value,
> +                               gpointer opaque)
> +{
> +    g_hash_table_insert(type_table_get(), key, value);
> +}
> +
>  void object_class_foreach(void (*fn)(ObjectClass *klass, void *opaque),
>                            const char *implements_type, bool include_abstract,
>                            void *opaque)
>  {
>      OCFData data = { fn, implements_type, include_abstract, opaque };
>  
> -    g_hash_table_foreach(type_table_get(), object_class_foreach_tramp, 
> &data);
> +    while (type_table_to_initialize &&
> +           g_hash_table_size(type_table_to_initialize) > 0) {
> +        g_hash_table_foreach(type_table_to_initialize, object_class_merge,
> +                             NULL);
> +        g_hash_table_destroy(type_table_to_initialize);
> +        type_table_to_initialize = NULL;
> +
> +        g_hash_table_foreach(type_table_get(), object_class_foreach_tramp,
> +                             &data);
> +    }
>  }
>  
>  int object_child_foreach(Object *obj, int (*fn)(Object *child, void *opaque),
> 


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