virtio/9p: verify device has config space

Some devices might not implement config space access
(e.g. remoteproc used not to - before 3.9).
virtio/9p needs config space access so make it
fail gracefully if not there.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 6 insertions, 0 deletions

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index daa749c8b3fb..d8e376a5f0f1 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -524,6 +524,12 @@ static int p9_virtio_probe(struct virtio_device *vdev)
         int err;
         struct virtio_chan *chan;
 
+        if (!vdev->config->get) {
+                dev_err(&vdev->dev, "%s failure: config access disabled\n",
+                        __func__);
+                return -EINVAL;
+        }
+
         chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL);
         if (!chan) {
                 pr_err("Failed to allocate virtio 9P channel\n");