regression on aarch64? panic on boot

[Keith Busch]

On Tue, Jan 17, 2023 at 07:37:35AM +0100, Christoph Hellwig wrote:
> On Tue, Jan 17, 2023 at 07:31:59AM +0100, Klaus Jensen wrote:
> > Good morning Christoph,
> > 
> > Yep, the above works.
> 
> Context for the newly added: This is dropping the newly added
> PROBE_PREFER_ASYNCHRONOUS in nvme, which causes Klaus' arm64 (but not
> other boot tests) to fail.  Any idea what could be going wrong there
> probably in userspace?

Prior to 6.2, the driver would do it's own async_schedule, and that
async probe function would flush the first scan work.
wait_for_device_probe() was then forced to wait for the scan_work to
complete, which brings up the root device.

We're not flushing the scan_work anymore from our probe, so this should
fix it for 6.2:

---
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index b294b41a149a7..ff97426749976 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -3046,6 +3046,7 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)

        nvme_start_ctrl(&dev->ctrl);
        nvme_put_ctrl(&dev->ctrl);
+       flush_work(&dev->ctrl.scan_work);
        return 0;

 out_disable:
--