On Mon, Mar 21, 2022 at 05:50:46PM +0100, Sven Peter wrote:
> +static bool apple_nvme_poll_cq(struct apple_nvme_queue *q,
> + struct io_comp_batch *iob)
> +{
> + bool found = false;
> +
> + while (apple_nvme_cqe_pending(q)) {
> + found = true;
> +
> + /*
> + * load-load control dependency between phase and the rest of
> + * the cqe requires a full read memory barrier
> + */
> + dma_rmb();
> + apple_nvme_handle_cqe(q, iob, q->cq_head);
> + apple_nvme_update_cq_head(q);
> + }
> +
> + if (found)
> + writel_relaxed(q->cq_head, q->cq_db);
Doesn't a relaxed write mean that a subsequent write can bypass the previous?
If so, that sounds like it can corrupt the cq head.
