Commit 7547881d authored by Matthew Wilcox's avatar Matthew Wilcox
Browse files

NVMe: Correct SQ doorbell semantics 



The value written to the doorbell needs to be the first free index in
the queue, not the most recently used index in the queue.

Signed-off-by: default avatarMatthew Wilcox <matthew.r.wilcox@intel.com>
parent 740216fc

drivers/block/nvme.c

+2 −2
Original line number Diff line number Diff line
@@ -246,9 +246,9 @@ static int nvme_submit_cmd(struct nvme_queue *nvmeq, struct nvme_command *cmd) 
	spin_lock_irqsave(&nvmeq->q_lock, flags);

	tail = nvmeq->sq_tail;

	memcpy(&nvmeq->sq_cmds[tail], cmd, sizeof(*cmd));

	writel(tail, nvmeq->q_db);

	if (++tail == nvmeq->q_depth)

		tail = 0;

	writel(tail, nvmeq->q_db);

	nvmeq->sq_tail = tail;

	spin_unlock_irqrestore(&nvmeq->q_lock, flags);
@@ -471,9 +471,9 @@ static int nvme_submit_bio_queue(struct nvme_queue *nvmeq, struct nvme_ns *ns, 
	cmnd->rw.control = cpu_to_le16(control);

	cmnd->rw.dsmgmt = cpu_to_le32(dsmgmt);



	writel(nvmeq->sq_tail, nvmeq->q_db);

	if (++nvmeq->sq_tail == nvmeq->q_depth)

		nvmeq->sq_tail = 0;

	writel(nvmeq->sq_tail, nvmeq->q_db);



	return 0;

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