#define io_uring_for_each_cqe(ring, head, cqe)    \
   /*        \
    * io_uring_smp_load_acquire() enforces the order of tail \
    * and CQE reads.      \
    */        \
   for (head = *(ring)->cq.khead;     \
        (cqe = (head != io_uring_smp_load_acquire((ring)->cq.ktail) ? \
    &(ring)->cq.cqes[head & (*(ring)->cq.kring_mask)] : NULL)); \
        head++)