io_uring_wait_cqe_timeout not returning on timeout?

[nibanks]

uint32_t eventq_dequeue(eventq* queue, eventq_cqe* events, uint32_t count, uint32_t wait_time) {
    int result;
    if (wait_time != UINT32_MAX) {
        struct __kernel_timespec timeout;
        timeout.tv_sec += (wait_time / 1000);
        timeout.tv_nsec += ((wait_time % 1000) * 1000000);
        printf("eventq_dequeue, waiting %u ms\n", wait_time);
        result = io_uring_wait_cqe_timeout(queue, events, &timeout);
    } else {
        printf("eventq_dequeue, waiting\n");
        result = io_uring_wait_cqe(queue, events);
    }
    printf("eventq_dequeue, %d\n", result);
    return result == 0 ? 1 : 0;
}

Full code: https://github.com/nibanks/eventq/blob/main/eventq.h#L224

The function above is supposed to wait up to wait_time milliseconds, returning 0 if timeout occurs. But the timeout part doesn't seem to be working. As you can see from some of the printfs, it starts waiting on the timeout, but doesn't actually return until I actually enqueue (io_uring_submit) a user event.

eventq_dequeue, waiting 100 ms
eventq_enqueue 32769
eventq_enqueue 32768
eventq_dequeue, 0
Echo event received

Do I have an incorrect understanding of io_uring_wait_cqe_timeout? Am I using it wrong?

[nibanks]

Ok. Apparently today is not my day. Yet another blunder on my part. The += above was copied from somewhere, and it should be simply =. Now it works as expected. Sorry for the noise.