list_empty
#define list_empty(a) ((a)->list_head.list_next == &(a)->list_head)
#define list_empty(a) ((a)->list_head.list_next == &(a)->list_head)
#define list_empty(a) ((a)->list_head.list_next == &(a)->list_head)
#define list_empty(a) ((a)->list_head.list_next == &(a)->list_head)
#define list_empty(list) (list_head(list) == NULL)