[PATCH 2/2] virtio_pmem: set device ready in probe()

[Jason Wang <jasowang@redhat.com>]

The NVDIMM region could be available before the virtio_device_ready()
that is called by virtio_dev_probe(). This means the driver tries to
use device before DRIVER_OK which violates the spec, fixing this by
set device ready before the nvdimm_pmem_region_create().

Note that this means the virtio_pmem_host_ack() could be triggered
before the creation of the nd region, this is safe since the
virtio_pmem_host_ack() since pmem_lock has been initialized and we
check if we've added any buffer before trying to proceed.

Fixes 6e84200c0a29 ("virtio-pmem: Add virtio pmem driver")
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/nvdimm/virtio_pmem.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c
index 48f8327d0431..173f2f5adaea 100644
--- a/drivers/nvdimm/virtio_pmem.c
+++ b/drivers/nvdimm/virtio_pmem.c
@@ -84,6 +84,17 @@ static int virtio_pmem_probe(struct virtio_device *vdev)
 	ndr_desc.provider_data = vdev;
 	set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
 	set_bit(ND_REGION_ASYNC, &ndr_desc.flags);
+	/*
+	 * The NVDIMM region could be available before the
+	 * virtio_device_ready() that is called by
+	 * virtio_dev_probe(), so we set device ready here.
+	 *
+	 * The callback - virtio_pmem_host_ack() is safe to be called
+	 * before the nvdimm_pmem_region_create() since the pmem_lock
+	 * has been initialized and legality of a used buffer is
+	 * validated before moving forward.
+	 */
+	virtio_device_ready(vdev);
 	nd_region = nvdimm_pmem_region_create(vpmem->nvdimm_bus, &ndr_desc);
 	if (!nd_region) {
 		dev_err(&vdev->dev, "failed to create nvdimm region\n");
@@ -92,6 +103,7 @@ static int virtio_pmem_probe(struct virtio_device *vdev)
 	}
 	return 0;
 out_nd:
+	virtio_reset_device(vdev);
 	nvdimm_bus_unregister(vpmem->nvdimm_bus);
 out_vq:
 	vdev->config->del_vqs(vdev);
-- 
2.25.1