Re: [PATCH net-next v4 01/13] list: Add list_next_entry_circular() and list_prev_entry_circular()

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Thu, Jan 13, 2022 at 06:06:15PM -0700, Ricardo Martinez wrote:
> Add macros to get the next or previous entries and wraparound if
> needed. For example, calling list_next_entry_circular() on the last
> element should return the first element in the list.

FWIW,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> Signed-off-by: Ricardo Martinez <ricardo.martinez@linux.intel.com>
> ---
>  include/linux/list.h | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/include/linux/list.h b/include/linux/list.h
> index dd6c2041d09c..c147eeb2d39d 100644
> --- a/include/linux/list.h
> +++ b/include/linux/list.h
> @@ -563,6 +563,19 @@ static inline void list_splice_tail_init(struct list_head *list,
>  #define list_next_entry(pos, member) \
>  	list_entry((pos)->member.next, typeof(*(pos)), member)
>  
> +/**
> + * list_next_entry_circular - get the next element in list
> + * @pos:	the type * to cursor.
> + * @head:	the list head to take the element from.
> + * @member:	the name of the list_head within the struct.
> + *
> + * Wraparound if pos is the last element (return the first element).
> + * Note, that list is expected to be not empty.
> + */
> +#define list_next_entry_circular(pos, head, member) \
> +	(list_is_last(&(pos)->member, head) ? \
> +	list_first_entry(head, typeof(*(pos)), member) : list_next_entry(pos, member))
> +
>  /**
>   * list_prev_entry - get the prev element in list
>   * @pos:	the type * to cursor
> @@ -571,6 +584,19 @@ static inline void list_splice_tail_init(struct list_head *list,
>  #define list_prev_entry(pos, member) \
>  	list_entry((pos)->member.prev, typeof(*(pos)), member)
>  
> +/**
> + * list_prev_entry_circular - get the prev element in list
> + * @pos:	the type * to cursor.
> + * @head:	the list head to take the element from.
> + * @member:	the name of the list_head within the struct.
> + *
> + * Wraparound if pos is the first element (return the last element).
> + * Note, that list is expected to be not empty.
> + */
> +#define list_prev_entry_circular(pos, head, member) \
> +	(list_is_first(&(pos)->member, head) ? \
> +	list_last_entry(head, typeof(*(pos)), member) : list_prev_entry(pos, member))
> +
>  /**
>   * list_for_each	-	iterate over a list
>   * @pos:	the &struct list_head to use as a loop cursor.
> -- 
> 2.17.1
> 

-- 
With Best Regards,
Andy Shevchenko