inline void *__list_find(struct list_head *head, size_t offset, char (*equality_func)(void*, void*), void *context)
{
    struct list_head *pos, *n;
    list_for_each_safe(pos, n, head)
    {
        void *obj = (void*)((unsigned long)pos-offset);
        if(equality_func(obj, context))
            return obj;
    }
    return NULL;
}

#define list_find(type, member, head, equality_func, context)    \
    __list_find(head, offsetof(type, member), equality_func, context)