struct __fifo_node_t {
        void *next;
};
typedef struct __fifo_node_t fifo_node_t;

struct __fifo_list_t {
        void *next;
        void *tail;
};
typedef struct __fifo_list_t fifo_list_t;

static inline void __fifo_list_push(fifo_list_t *head, fifo_node_t *node)
{
        fifo_node_t *prev;

        node->next = head;
        prev = atomic_xchg64(&head->tail, node);
        prev->next = node;
}

static inline fifo_node_t *__fifo_list_pop(fifo_list_t *head)
{
        fifo_node_t *node;
        while ((node = ACCESS_ONCE(head->next)) != head) {
                fifo_node_t *next = ACCESS_ONCE(node->next);
                if (cmpxchg_eq(&head->next, node, next) == node) {
                        if (cmpxchg_eq(&head->tail, node, head) != node &&
                            next == head)
                                while (ACCESS_ONCE(head->next) == next)
                                        head->next = ACCESS_ONCE(node->next);
                        return node;
                }
        }
        return NULL;
}

static inline void __fifo_list_init(fifo_list_t *head)
{
        head->next = head->tail = head;
}