Commit 38210800 authored by Keith Busch's avatar Keith Busch Committed by Christoph Hellwig
Browse files

Revert "nvme-pci: remove last_sq_tail" 

Multiple CPUs may be mapped to the same hctx, allowing mulitple
submission contexts to attempt commit_rqs(). We need to verify we're
not writing the same doorbell value multiple times since that's a spec
violation.

Revert commit 54b2fcee.

Link: https://bugzilla.redhat.com/show_bug.cgi?id=1878596


Reported-by: default avatar"B.L. Jones" <brandon.gustav@googlemail.com>
Signed-off-by: default avatarKeith Busch <kbusch@kernel.org>
parent 65ff5cd0

drivers/nvme/host/pci.c

+19 −4
Original line number Diff line number Diff line
@@ -198,6 +198,7 @@ struct nvme_queue { 
	u32 q_depth;

	u16 cq_vector;

	u16 sq_tail;

	u16 last_sq_tail;

	u16 cq_head;

	u16 qid;

	u8 cq_phase;
@@ -455,11 +456,24 @@ static int nvme_pci_map_queues(struct blk_mq_tag_set *set) 
	return 0;

}



static inline void nvme_write_sq_db(struct nvme_queue *nvmeq)

/*

 * Write sq tail if we are asked to, or if the next command would wrap.

 */

static inline void nvme_write_sq_db(struct nvme_queue *nvmeq, bool write_sq)

{

	if (!write_sq) {

		u16 next_tail = nvmeq->sq_tail + 1;



		if (next_tail == nvmeq->q_depth)

			next_tail = 0;

		if (next_tail != nvmeq->last_sq_tail)

			return;

	}



	if (nvme_dbbuf_update_and_check_event(nvmeq->sq_tail,

			nvmeq->dbbuf_sq_db, nvmeq->dbbuf_sq_ei))

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

	nvmeq->last_sq_tail = nvmeq->sq_tail;

}



/**
@@ -476,8 +490,7 @@ static void nvme_submit_cmd(struct nvme_queue *nvmeq, struct nvme_command *cmd, 
	       cmd, sizeof(*cmd));

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

		nvmeq->sq_tail = 0;

	if (write_sq)

		nvme_write_sq_db(nvmeq);

	nvme_write_sq_db(nvmeq, write_sq);

	spin_unlock(&nvmeq->sq_lock);

}
@@ -486,7 +499,8 @@ static void nvme_commit_rqs(struct blk_mq_hw_ctx *hctx) 
	struct nvme_queue *nvmeq = hctx->driver_data;



	spin_lock(&nvmeq->sq_lock);

	nvme_write_sq_db(nvmeq);

	if (nvmeq->sq_tail != nvmeq->last_sq_tail)

		nvme_write_sq_db(nvmeq, true);

	spin_unlock(&nvmeq->sq_lock);

}
@@ -1496,6 +1510,7 @@ static void nvme_init_queue(struct nvme_queue *nvmeq, u16 qid) 
	struct nvme_dev *dev = nvmeq->dev;



	nvmeq->sq_tail = 0;

	nvmeq->last_sq_tail = 0;

	nvmeq->cq_head = 0;

	nvmeq->cq_phase = 1;

	nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];

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