Re: [Qemu-ppc] [Qemu-devel] [QEMU PATCH v7 2/3] migration: migrate QTAILQ

[Halil Pasic]

On 10/22/2016 12:52 AM, Jianjun Duan wrote:
> +#define RAW_FIELD(base, offset)                                              
>   \
> +        ((char *) (base) + offset)
> +

Seems you partially adopted Paolo's suggestion for improving the
macros. Is there a particular reason why you did not follow it more
closely? I find the solution with field_at_offset(base, offset, type)
more readable than with RAW_FIELD(base, offset).

> +/*
> + * Offsets of layout of a tail queue head.
> + */
> +#define QTAILQ_FIRST_OFFSET 0
> +#define QTAILQ_LAST_OFFSET (sizeof(void *))
> +/*
> + * Raw access of elements of a tail queue
> + */
> +#define QTAILQ_RAW_FIRST(head)                                               
>   \
> +        (*((void **) (RAW_FIELD(head,  QTAILQ_FIRST_OFFSET))))
> +#define QTAILQ_RAW_LAST(head)                                                
>   \
> +        (*((void ***) (RAW_FIELD(head,  QTAILQ_LAST_OFFSET))))
> +
> +/*
> + * Offsets of layout of a tail queue element.
> + */
> +#define QTAILQ_NEXT_OFFSET 0
> +#define QTAILQ_PREV_OFFSET (sizeof(void *))
> +
> +/*
> + * Raw access of elements of a tail entry
> + */
> +#define QTAILQ_RAW_NEXT(elm, entry)                                          
>   \
> +        (*((void **) (RAW_FIELD(elm, entry + QTAILQ_NEXT_OFFSET))))
> +#define QTAILQ_RAW_PREV(elm, entry)                                          
>   \
> +        (*((void ***) (RAW_FIELD(elm, entry + QTAILQ_PREV_OFFSET))))
> +/*
> + * Tail queue tranversal using pointer arithmetic.
> + */