NVMe: Shutdown controller only for power-off

BugLink: http://bugs.launchpad.net/bugs/1531539

We don't need to shutdown a controller for a reset. A controller in a
shutdown state may take longer to become ready than one that was simply
disabled. This patch has the driver shut down a controller only if the
device is about to be powered off or being removed. When taking the
controller down for a reset reason, the controller will be disabled
instead.

Function names have been updated in this patch to reflect their changed
semantics.
Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
(cherry picked from commit a5cdb68c)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/nvme/host/pci.c

@@ -87,7 +87,7 @@ struct nvme_queue;
 static int nvme_reset(struct nvme_dev *dev);
 static void nvme_process_cq(struct nvme_queue *nvmeq);
 static void nvme_remove_dead_ctrl(struct nvme_dev *dev);
-static void nvme_dev_shutdown(struct nvme_dev *dev);
+static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown);
 
 /*
  * Represents an NVM Express device.  Each nvme_dev is a PCI function.
@@ -932,7 +932,7 @@ static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved)
 		dev_warn(dev->dev,
 			 "I/O %d QID %d timeout, disable controller\n",
 			 req->tag, nvmeq->qid);
-		nvme_dev_shutdown(dev);
+		nvme_dev_disable(dev, false);
 		req->errors = NVME_SC_CANCELLED;
 		return BLK_EH_HANDLED;
 	}
@@ -946,7 +946,7 @@ static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved)
 		dev_warn(dev->dev,
 			 "I/O %d QID %d timeout, reset controller\n",
 			 req->tag, nvmeq->qid);
-		nvme_dev_shutdown(dev);
+		nvme_dev_disable(dev, false);
 		queue_work(nvme_workq, &dev->reset_work);
 
 		/*
@@ -1065,21 +1065,20 @@ static void nvme_clear_queue(struct nvme_queue *nvmeq)
 	spin_unlock_irq(&nvmeq->q_lock);
 }
 
-static void nvme_disable_queue(struct nvme_dev *dev, int qid)
+static void nvme_disable_admin_queue(struct nvme_dev *dev, bool shutdown)
 {
-	struct nvme_queue *nvmeq = dev->queues[qid];
+	struct nvme_queue *nvmeq = dev->queues[0];
 
 	if (!nvmeq)
 		return;
 	if (nvme_suspend_queue(nvmeq))
 		return;
 
-	/* Don't tell the adapter to delete the admin queue.
-	 * Don't tell a removed adapter to delete IO queues. */
-	if (qid && readl(dev->bar + NVME_REG_CSTS) != -1) {
-		adapter_delete_sq(dev, qid);
-		adapter_delete_cq(dev, qid);
-	}
+	if (shutdown)
+		nvme_shutdown_ctrl(&dev->ctrl);
+	else
+		nvme_disable_ctrl(&dev->ctrl, lo_hi_readq(
+						dev->bar + NVME_REG_CAP));
 
 	spin_lock_irq(&nvmeq->q_lock);
 	nvme_process_cq(nvmeq);
@@ -1830,7 +1829,7 @@ static void nvme_dev_list_remove(struct nvme_dev *dev)
 		kthread_stop(tmp);
 }
 
-static void nvme_dev_shutdown(struct nvme_dev *dev)
+static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown)
 {
 	int i;
 	u32 csts = -1;
@@ -1849,8 +1848,7 @@ static void nvme_dev_shutdown(struct nvme_dev *dev)
 		}
 	} else {
 		nvme_disable_io_queues(dev);
-		nvme_shutdown_ctrl(&dev->ctrl);
-		nvme_disable_queue(dev, 0);
+		nvme_disable_admin_queue(dev, shutdown);
 	}
 	nvme_dev_unmap(dev);
 
@@ -1909,7 +1907,7 @@ static void nvme_reset_work(struct work_struct *work)
 	 * moving on.
 	 */
 	if (dev->bar)
-		nvme_dev_shutdown(dev);
+		nvme_dev_disable(dev, false);
 
 	set_bit(NVME_CTRL_RESETTING, &dev->flags);
 
@@ -1963,7 +1961,7 @@ static void nvme_reset_work(struct work_struct *work)
 	dev->ctrl.admin_q = NULL;
 	dev->queues[0]->tags = NULL;
  disable:
-	nvme_disable_queue(dev, 0);
+	nvme_disable_admin_queue(dev, false);
  unmap:
 	nvme_dev_unmap(dev);
  out:
@@ -2098,7 +2096,7 @@ static void nvme_reset_notify(struct pci_dev *pdev, bool prepare)
 	struct nvme_dev *dev = pci_get_drvdata(pdev);
 
 	if (prepare)
-		nvme_dev_shutdown(dev);
+		nvme_dev_disable(dev, false);
 	else
 		queue_work(nvme_workq, &dev->reset_work);
 }
@@ -2106,7 +2104,7 @@ static void nvme_reset_notify(struct pci_dev *pdev, bool prepare)
 static void nvme_shutdown(struct pci_dev *pdev)
 {
 	struct nvme_dev *dev = pci_get_drvdata(pdev);
-	nvme_dev_shutdown(dev);
+	nvme_dev_disable(dev, true);
 }
 
 static void nvme_remove(struct pci_dev *pdev)
@@ -2122,7 +2120,7 @@ static void nvme_remove(struct pci_dev *pdev)
 	flush_work(&dev->scan_work);
 	nvme_remove_namespaces(&dev->ctrl);
 	nvme_uninit_ctrl(&dev->ctrl);
-	nvme_dev_shutdown(dev);
+	nvme_dev_disable(dev, true);
 	nvme_dev_remove_admin(dev);
 	nvme_free_queues(dev, 0);
 	nvme_release_cmb(dev);
@@ -2136,7 +2134,7 @@ static int nvme_suspend(struct device *dev)
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct nvme_dev *ndev = pci_get_drvdata(pdev);
 
-	nvme_dev_shutdown(ndev);
+	nvme_dev_disable(ndev, true);
 	return 0;
 }
 
@@ -2167,7 +2165,7 @@ static pci_ers_result_t nvme_error_detected(struct pci_dev *pdev,
 	case pci_channel_io_normal:
 		return PCI_ERS_RESULT_CAN_RECOVER;
 	case pci_channel_io_frozen:
-		nvme_dev_shutdown(dev);
+		nvme_dev_disable(dev, false);
 		return PCI_ERS_RESULT_NEED_RESET;
 	case pci_channel_io_perm_failure:
 		return PCI_ERS_RESULT_DISCONNECT;