[PATCH 5/9] xen-blkfront: add error handling support for add_disk()

[Luis Chamberlain <mcgrof@xxxxxxxxxx>]

We never checked for errors on device_add_disk() as this function
returned void. Now that this is fixed, use the shiny new error
handling. The function xlvbd_alloc_gendisk() typically does the
unwinding on error on allocating the disk and creating the tag,
but since all that error handling was stuffed inside
xlvbd_alloc_gendisk() we must repeat the tag free'ing as well.

We set the info->rq to NULL to ensure blkif_free() doesn't crash
on blk_mq_stop_hw_queues() on device_add_disk() error as the queue
will be long gone by then.

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
---
 drivers/block/xen-blkfront.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index df0deb927760..8e3983e456f3 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -2386,7 +2386,13 @@ static void blkfront_connect(struct blkfront_info *info)
        for_each_rinfo(info, rinfo, i)
                kick_pending_request_queues(rinfo);
 
-       device_add_disk(&info->xbdev->dev, info->gd, NULL);
+       err = device_add_disk(&info->xbdev->dev, info->gd, NULL);
+       if (err) {
+               blk_cleanup_disk(info->gd);
+               blk_mq_free_tag_set(&info->tag_set);
+               info->rq = NULL;
+               goto fail;
+       }
 
        info->is_ready = 1;
        return;
-- 
2.30.2