From 0ab4c94c844cb3953adedbd27adc378b3cf31d9e Mon Sep 17 00:00:00 2001 From: Peter Crosthwaite Date: Wed, 27 Nov 2013 20:27:33 -0800 Subject: [PATCH] qom: Split out object and class caches MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The object-cast and class-cast caches cannot be shared because class caching is conditional on the target type not being an interface and object caching is unconditional. Leads to a bug when a class cast to an interface follows an object cast to the same interface type: FooObject = FOO(obj); FooClass = FOO_GET_CLASS(obj); Where TYPE_FOO is an interface. The first (object) cast will be successful and cache the casting result (i.e. TYPE_FOO will be cached). The second (class) cast will then check the shared cast cache and register a hit. The issue is, when a class cast hits in the cache it just returns a pointer cast of the input class (i.e. the concrete class). When casting to an interface, the cast itself must return the interface class, not the concrete class. The implementation of class cast caching already ensures that the returned cast result is only a pointer cast before caching. The object cast logic however does not have this check. Resolve by just splitting the object and class caches. Cc: qemu-stable@nongnu.org Signed-off-by: Peter Crosthwaite Reviewed-by: Paolo Bonzini Tested-by: Nathan Rossi Reviewed-by: Edgar E. Iglesias Signed-off-by: Andreas Färber --- include/qom/object.h | 3 ++- qom/object.c | 13 +++++++------ 2 files changed, 9 insertions(+), 7 deletions(-) diff --git a/include/qom/object.h b/include/qom/object.h index a275db2092..5f78847d68 100644 --- a/include/qom/object.h +++ b/include/qom/object.h @@ -358,7 +358,8 @@ struct ObjectClass Type type; GSList *interfaces; - const char *cast_cache[OBJECT_CLASS_CAST_CACHE]; + const char *object_cast_cache[OBJECT_CLASS_CAST_CACHE]; + const char *class_cast_cache[OBJECT_CLASS_CAST_CACHE]; ObjectUnparent *unparent; }; diff --git a/qom/object.c b/qom/object.c index fc19cf676a..21b5a0bbe1 100644 --- a/qom/object.c +++ b/qom/object.c @@ -458,7 +458,7 @@ Object *object_dynamic_cast_assert(Object *obj, const char *typename, Object *inst; for (i = 0; obj && i < OBJECT_CLASS_CAST_CACHE; i++) { - if (obj->class->cast_cache[i] == typename) { + if (obj->class->object_cast_cache[i] == typename) { goto out; } } @@ -475,9 +475,10 @@ Object *object_dynamic_cast_assert(Object *obj, const char *typename, if (obj && obj == inst) { for (i = 1; i < OBJECT_CLASS_CAST_CACHE; i++) { - obj->class->cast_cache[i - 1] = obj->class->cast_cache[i]; + obj->class->object_cast_cache[i - 1] = + obj->class->object_cast_cache[i]; } - obj->class->cast_cache[i - 1] = typename; + obj->class->object_cast_cache[i - 1] = typename; } out: @@ -547,7 +548,7 @@ ObjectClass *object_class_dynamic_cast_assert(ObjectClass *class, int i; for (i = 0; class && i < OBJECT_CLASS_CAST_CACHE; i++) { - if (class->cast_cache[i] == typename) { + if (class->class_cast_cache[i] == typename) { ret = class; goto out; } @@ -568,9 +569,9 @@ ObjectClass *object_class_dynamic_cast_assert(ObjectClass *class, #ifdef CONFIG_QOM_CAST_DEBUG if (class && ret == class) { for (i = 1; i < OBJECT_CLASS_CAST_CACHE; i++) { - class->cast_cache[i - 1] = class->cast_cache[i]; + class->class_cast_cache[i - 1] = class->class_cast_cache[i]; } - class->cast_cache[i - 1] = typename; + class->class_cast_cache[i - 1] = typename; } out: #endif