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| author | Alex Bennée <alex.bennee@linaro.org> | 2016-09-30 22:30:57 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-10-04 10:00:26 +0200 |
| commit | b6b3ccfda015dcd5ab50f70c189ee5cc6c622e91 (patch) | |
| tree | ddd09714020bda3ea47d837ca64fbc0d23f04265 /qom/object.c | |
| parent | f96a8cc3c633b25d9269337408ae2417ebbbad8e (diff) | |
| download | qemu-b6b3ccfda015dcd5ab50f70c189ee5cc6c622e91.tar.gz | |
qom/object: update class cache atomically
The idiom CPU_GET_CLASS(cpu) is fairly extensively used in various
threads and trips of ThreadSanitizer due to the fact it updates
obj->class->object_cast_cache behind the scenes. As this is just a
fast-path cache there is no need to lock updates.
However to ensure defined C11 behaviour across threads we need to use
the plain atomic_read/set primitives and keep the sanitizer happy.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20160930213106.20186-7-alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'qom/object.c')
| -rw-r--r-- | qom/object.c | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/qom/object.c b/qom/object.c index 8166b7dace..7a05e35ed9 100644 --- a/qom/object.c +++ b/qom/object.c @@ -614,7 +614,7 @@ 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->object_cast_cache[i] == typename) { + if (atomic_read(&obj->class->object_cast_cache[i]) == typename) { goto out; } } @@ -631,10 +631,10 @@ 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->object_cast_cache[i - 1] = - obj->class->object_cast_cache[i]; + atomic_set(&obj->class->object_cast_cache[i - 1], + atomic_read(&obj->class->object_cast_cache[i])); } - obj->class->object_cast_cache[i - 1] = typename; + atomic_set(&obj->class->object_cast_cache[i - 1], typename); } out: @@ -704,7 +704,7 @@ ObjectClass *object_class_dynamic_cast_assert(ObjectClass *class, int i; for (i = 0; class && i < OBJECT_CLASS_CAST_CACHE; i++) { - if (class->class_cast_cache[i] == typename) { + if (atomic_read(&class->class_cast_cache[i]) == typename) { ret = class; goto out; } @@ -725,9 +725,10 @@ 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->class_cast_cache[i - 1] = class->class_cast_cache[i]; + atomic_set(&class->class_cast_cache[i - 1], + atomic_read(&class->class_cast_cache[i])); } - class->class_cast_cache[i - 1] = typename; + atomic_set(&class->class_cast_cache[i - 1], typename); } out: #endif |