nvme/pci: Use async_schedule for initial reset work

This patch schedules the initial controller reset in an async_domain
so that it can be synchronized from wait_for_device_probe(). This way
the kernel waits for the initial nvme controller scan to complete for
all devices before proceeding with the boot sequence, which may have
nvme dependencies.
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Tested-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>

drivers/nvme/host/pci.c

@@ -13,6 +13,7 @@
  */
 
 #include <linux/aer.h>
+#include <linux/async.h>
 #include <linux/blkdev.h>
 #include <linux/blk-mq.h>
 #include <linux/blk-mq-pci.h>
@@ -2488,6 +2489,13 @@ static unsigned long check_vendor_combination_bug(struct pci_dev *pdev)
 	return 0;
 }
 
+static void nvme_async_probe(void *data, async_cookie_t cookie)
+{
+	struct nvme_dev *dev = data;
+	nvme_reset_ctrl_sync(&dev->ctrl);
+	flush_work(&dev->ctrl.scan_work);
+}
+
 static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 {
 	int node, result = -ENOMEM;
@@ -2532,7 +2540,7 @@ 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);
 
 	return 0;