virtio/blk: verify device has config space

Some devices might not implement config space access
(e.g. remoteproc used not to - before 3.9).
virtio/blk 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>

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index cdfbd21e35975178fa0c4cece78a354ef1d53007..b72c11a10f409b6cc1fb4b7795d866ff01dd8b00 100644 (file)
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -575,6 +575,12 @@ static int virtblk_probe(struct virtio_device *vdev)
        u16 min_io_size;
        u8 physical_block_exp, alignment_offset;
 
+       if (!vdev->config->get) {
+               dev_err(&vdev->dev, "%s failure: config access disabled\n",
+                       __func__);
+               return -EINVAL;
+       }
+
        err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
                             GFP_KERNEL);
        if (err < 0)