[PATCH 2/6 Xenial SRU V2] nvme: don't poll the CQ from the kthread

[Tim Gardner]

From: Christoph Hellwig <hch at lst.de>

BugLink: http://bugs.launchpad.net/bugs/1602724

There is no reason to do unconditional polling of CQs per the NVMe
spec.

Signed-off-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Keith Busch <keith.busch at intel.com>
Reviewed-by: Sagi Grimberg <sagig at mellanox.com>
Reviewed-by: Johannes Thumshirn <jthumshirn at suse.de>
Signed-off-by: Jens Axboe <axboe at fb.com>
(cherry picked from commit 79f2b358c9ba373943a9284be2861fde58291c4e)
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---
 drivers/nvme/host/pci.c | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 277fc6c..f1069d9 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1185,9 +1185,6 @@ static struct nvme_queue *nvme_alloc_queue(struct nvme_dev *dev, int qid,
 	nvmeq->qid = qid;
 	nvmeq->cq_vector = -1;
 	dev->queues[qid] = nvmeq;
-
-	/* make sure queue descriptor is set before queue count, for kthread */
-	mb();
 	dev->queue_count++;
 
 	return nvmeq;
@@ -1380,7 +1377,6 @@ static int nvme_kthread(void *data)
 		set_current_state(TASK_INTERRUPTIBLE);
 		spin_lock(&dev_list_lock);
 		list_for_each_entry_safe(dev, next, &dev_list, node) {
-			int i;
 			u32 csts = readl(dev->bar + NVME_REG_CSTS);
 
 			/*
@@ -1398,14 +1394,6 @@ static int nvme_kthread(void *data)
 				}
 				continue;
 			}
-			for (i = 0; i < dev->queue_count; i++) {
-				struct nvme_queue *nvmeq = dev->queues[i];
-				if (!nvmeq)
-					continue;
-				spin_lock_irq(&nvmeq->q_lock);
-				nvme_process_cq(nvmeq);
-				spin_unlock_irq(&nvmeq->q_lock);
-			}
 		}
 		spin_unlock(&dev_list_lock);
 		schedule_timeout(round_jiffies_relative(HZ));
-- 
1.9.1