floppy: Cleanup disk->queue before caling put_disk() if add_disk() was never called

add_disk() takes gendisk reference on request queue. If driver failed during
initialization and never called add_disk() then that extra reference is not
taken. That reference is put in put_disk(). floppy driver allocates the
disk, allocates queue, sets disk->queue and then relizes that floppy
controller is not present. It tries to tear down everything and tries to
put a reference down in put_disk() which was never taken.

In such error cases cleanup disk->queue before calling put_disk() so that
we never try to put down a reference which was never taken in first place.

Reported-and-tested-by: Suresh Jayaraman <sjayaraman@suse.com>
Tested-by: Dirk Gouders <gouders@et.bocholt.fh-gelsenkirchen.de>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 510fb10..401ba78 100644 (file)
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -4368,8 +4368,14 @@ out_unreg_blkdev:
 out_put_disk:
        while (dr--) {
                del_timer_sync(&motor_off_timer[dr]);
-               if (disks[dr]->queue)
+               if (disks[dr]->queue) {
                        blk_cleanup_queue(disks[dr]->queue);
+                       /*
+                        * put_disk() is not paired with add_disk() and
+                        * will put queue reference one extra time. fix it.
+                        */
+                       disks[dr]->queue = NULL;
+               }
                put_disk(disks[dr]);
        }
        return err;