On 24/05/2016 19:55, Jianjun Duan wrote:
> +/*
> + * Offsets of layout of a tail queue head.
> + */
> +#define QTAILQ_FIRST_OFFSET(head_type) \
> + ((size_t) ((char *) &((head_type *)0)->tqh_first - (char *)0))
> +
> +#define QTAILQ_LAST_OFFSET(head_type) \
> + ((size_t) ((char *) &((head_type *)0)->tqh_last - (char *)0))
> +
> +/*
> + * Offsets of layout of a tail queue element.
> + */
> +#define QTAILQ_NEXT_OFFSET(ele_type, field) \
> + ((size_t) ((char *) &((ele_type *)0)->field.tqe_next - \
> + (char *) &((ele_type *)0)->field))
> +
> +#define QTAILQ_PREV_OFFSET(ele_type, field) \
> + ((size_t) ((char *) &((ele_type *)0)->field.tqe_prev - \
> + (char *) &((ele_type *)0)->field))
Please use offsetof.
> + /*
> + * Following 3 fields are for VMStateField which needs customized
> handling,
> + * such as QTAILQ in qemu/queue.h, lists, and tree.
> + */
> + const void *meta_data;
> + int (*extend_get)(QEMUFile *f, const void *metadata, void *opaque);
> + void (*extend_put)(QEMUFile *f, const void *metadata, void *opaque,
> + QJSON *vmdesc);
> } VMStateField;
Do not add these two function pointers to VMStateField, instead add
QJSON* and VMStateField* arguments as needed to VMStateInfo's get and put.
> +#define VMSTATE_QTAILQ_METADATA(_field, _state, _type, _next, _vmsd) { \
> + .first = QTAILQ_FIRST_OFFSET(typeof_field(_state, _field)), \
> + .last = QTAILQ_LAST_OFFSET(typeof_field(_state, _field)), \
> + .next = QTAILQ_NEXT_OFFSET(_type, _next), \
> + .prev = QTAILQ_PREV_OFFSET(_type, _next), \
> + .entry = offsetof(_type, _next), \
> + .size = sizeof(_type), \
> + .vmsd = &(_vmsd), \
> +}
.last and .prev are unnecessary, since they come just after .first and
.next (and their use is hidden behind QTAILQ_RAW_*). .first and .next
can be placed in .offset and .num_offset respectively. So you don't
really need an extra metadata struct.
If you prefer you could have something like
union {
size_t num_offset; /* VMS_VARRAY */
size_t size_offset; /* VMS_VBUFFER */
size_t next_offset; /* VMS_TAILQ */
} offsets;
Thanks,
Paolo
