scsi: sr: Fix sr_probe() missing deallocate of device minor

BugLink: https://bugs.launchpad.net/bugs/1885932

[ Upstream commit 6555781b ]

If the cdrom fails to be registered then the device minor should be
deallocated.

Link: https://lore.kernel.org/r/072dac4b-8402-4de8-36bd-47e7588969cd@0882a8b5-c6c3-11e9-b005-00805fc181feSigned-off-by: Simon Arlott <simon@octiron.net>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

drivers/scsi/sr.c

@@ -746,7 +746,7 @@ static int sr_probe(struct device *dev)
 	cd->cdi.disk = disk;
 
 	if (register_cdrom(&cd->cdi))
-		goto fail_put;
+		goto fail_minor;
 
 	/*
 	 * Initialize block layer runtime PM stuffs before the
@@ -764,6 +764,10 @@ static int sr_probe(struct device *dev)
 
 	return 0;
 
+fail_minor:
+	spin_lock(&sr_index_lock);
+	clear_bit(minor, sr_index_bits);
+	spin_unlock(&sr_index_lock);
 fail_put:
 	put_disk(disk);
 fail_free: