Commit 74943d45 authored by Keith Busch's avatar Keith Busch Committed by Jens Axboe
Browse files

nvme-pci: remove volatile cqes 



The completion queue entry is not volatile once the phase is confirmed.
Remove the volatile keywords and check the phase using the appropriate
READ_ONCE() accessor, allowing the compiler to optimize the remaining
completion path.

Signed-off-by: default avatarKeith Busch <kbusch@kernel.org>
Reviewed-by: default avatarSagi Grimberg <sagi@grimberg.me>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent b04df85d

drivers/nvme/host/pci.c

+5 −4
Original line number Diff line number Diff line
@@ -166,7 +166,7 @@ struct nvme_queue { 
	void *sq_cmds;

	 /* only used for poll queues: */

	spinlock_t cq_poll_lock ____cacheline_aligned_in_smp;

	volatile struct nvme_completion *cqes;

	struct nvme_completion *cqes;

	dma_addr_t sq_dma_addr;

	dma_addr_t cq_dma_addr;

	u32 __iomem *q_db;
@@ -922,8 +922,9 @@ static void nvme_pci_complete_rq(struct request *req) 
/* We read the CQE phase first to check if the rest of the entry is valid */

static inline bool nvme_cqe_pending(struct nvme_queue *nvmeq)

{

	return (le16_to_cpu(nvmeq->cqes[nvmeq->cq_head].status) & 1) ==

			nvmeq->cq_phase;

	struct nvme_completion *hcqe = &nvmeq->cqes[nvmeq->cq_head];



	return (le16_to_cpu(READ_ONCE(hcqe->status)) & 1) == nvmeq->cq_phase;

}



static inline void nvme_ring_cq_doorbell(struct nvme_queue *nvmeq)
@@ -944,7 +945,7 @@ static inline struct blk_mq_tags *nvme_queue_tagset(struct nvme_queue *nvmeq) 


static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx)

{

	volatile struct nvme_completion *cqe = &nvmeq->cqes[idx];

	struct nvme_completion *cqe = &nvmeq->cqes[idx];

	struct request *req;



	if (unlikely(cqe->command_id >= nvmeq->q_depth)) {

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