[PATCH] nvme: Boot as soon as the boot controller has been probed

[Bart Van Assche]

The following two issues have been introduced by commit 1811977568e0
("nvme/pci: Use async_schedule for initial reset work"):
- The boot process waits until all NVMe controllers have been probed
  instead of only waiting until the boot controller has been probed.
  This slows down the boot process.
- Some of the controller probing work happens asynchronously without
  the device core being aware of this.

Hence this patch that makes all probing work happen from nvme_probe()
and that tells the device core to probe multiple NVMe controllers
concurrently by setting PROBE_PREFER_ASYNCHRONOUS.

Cc: Mikulas Patocka <mpatocka at redhat.com>
Cc: Keith Busch <keith.busch at intel.com>
Cc: Greg KH <gregkh at linuxfoundation.org>
Signed-off-by: Bart Van Assche <bvanassche at acm.org>
---
 drivers/nvme/host/pci.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 0578ff253c47..703bb3aee817 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -6,7 +6,6 @@
 
 #include <linux/acpi.h>
 #include <linux/aer.h>
-#include <linux/async.h>
 #include <linux/blkdev.h>
 #include <linux/blk-mq.h>
 #include <linux/blk-mq-pci.h>
@@ -2821,15 +2820,6 @@ static inline bool nvme_acpi_storage_d3(struct pci_dev *dev)
 }
 #endif /* CONFIG_ACPI */
 
-static void nvme_async_probe(void *data, async_cookie_t cookie)
-{
-	struct nvme_dev *dev = data;
-
-	flush_work(&dev->ctrl.reset_work);
-	flush_work(&dev->ctrl.scan_work);
-	nvme_put_ctrl(&dev->ctrl);
-}
-
 static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 {
 	int node, result = -ENOMEM;
@@ -2903,8 +2893,16 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
 	dev_info(dev->ctrl.device, "pci function %s\n", dev_name(&pdev->dev));
 
-	nvme_reset_ctrl(&dev->ctrl);
-	async_schedule(nvme_async_probe, dev);
+	if (nvme_reset_ctrl(&dev->ctrl) == 0) {
+		/*
+		 * Since reset_work is scheduled on the context of
+		 * nvme_reset_wq and since that workqueue is not used for
+		 * probing devices, waiting until reset_work from nvme_probe()
+		 * is fine.
+		 */
+		flush_work(&dev->ctrl.reset_work);
+	}
+	nvme_put_ctrl(&dev->ctrl);
 
 	return 0;
 
@@ -3221,11 +3219,12 @@ static struct pci_driver nvme_driver = {
 	.probe		= nvme_probe,
 	.remove		= nvme_remove,
 	.shutdown	= nvme_shutdown,
-#ifdef CONFIG_PM_SLEEP
 	.driver		= {
+#ifdef CONFIG_PM_SLEEP
 		.pm	= &nvme_dev_pm_ops,
-	},
 #endif
+		.probe_type	= PROBE_PREFER_ASYNCHRONOUS,
+	},
 	.sriov_configure = pci_sriov_configure_simple,
 	.err_handler	= &nvme_err_handler,
 };