Re: [Qemu-devel] [PATCH v6 4/5] qobject: modify qobject_ref() to return obj

[Eric Blake <eblake@redhat.com>]

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On 04/19/2018 10:01 AM, Marc-André Lureau wrote:
> For convenience and clarity, make it possible to call qobject_ref() at
> the time when the reference is associated with a variable, or
> argument, by making qobject_ref() return the same pointer as given.
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>

You've made some substantial changes to the macro, I would have dropped
R-b to ensure those changes get reviewed.  In particular,

> ---

> +++ b/include/qapi/qmp/qobject.h
> @@ -72,11 +72,12 @@ static inline void qobject_init(QObject *obj, QType type)
>      obj->base.type = type;
>  }
>  
> -static inline void qobject_ref_impl(QObject *obj)
> +static inline void *qobject_ref_impl(QObject *obj)
>  {
>      if (obj) {
>          obj->base.refcnt++;
>      }
> +    return obj;

This hunk is now useless,

> @@ -103,8 +104,15 @@ static inline void qobject_unref_impl(QObject *obj)
>  
>  /**
>   * qobject_ref(): Increment QObject's reference count
> + *
> + * Returns: the same @obj. The type of @obj will be propagated to the
> + * return type.
>   */
> -#define qobject_ref(obj) qobject_ref_impl(QOBJECT(obj))
> +#define qobject_ref(obj) ({                     \
> +    typeof(obj) _o = (obj);                     \
> +    qobject_ref_impl(QOBJECT(_o));              \
> +    _o;                                         \

since nothing ever uses the return value.

But that said, I'm still okay with R-b with or without the useless hunk.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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