block: remove parent device reference from struct bsg_class_device

Bsg holding a reference to the parent device may result in a crash if a
bsg file handle is closed after the parent device driver has unloaded.

Holding a reference is not really needed: the parent device must exist
between bsg_register_queue and bsg_unregister_queue.  Before the device
goes away the caller does blk_cleanup_queue so that all in-flight
requests to the device are gone and all new requests cannot pass beyond
the queue.  The queue itself is a refcounted object and it will stay
alive with a bsg file.

Based on analysis, previous patch and changelog from Anatoliy Glagolev.

Reported-by: Anatoliy Glagolev <glagolig@gmail.com>
Reviewed-by: James E.J. Bottomley <jejb@linux.vnet.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 1 insertions, 5 deletions

diff --git a/include/linux/bsg.h b/include/linux/bsg.h
index 0c7dd9ceb139..dac37b6e00ec 100644
--- a/include/linux/bsg.h
+++ b/include/linux/bsg.h
@@ -17,17 +17,13 @@ struct bsg_ops {
 
 struct bsg_class_device {
 	struct device *class_dev;
-	struct device *parent;
 	int minor;
 	struct request_queue *queue;
-	struct kref ref;
 	const struct bsg_ops *ops;
-	void (*release)(struct device *);
 };
 
 int bsg_register_queue(struct request_queue *q, struct device *parent,
-		const char *name, const struct bsg_ops *ops,
-		void (*release)(struct device *));
+		const char *name, const struct bsg_ops *ops);
 int bsg_scsi_register_queue(struct request_queue *q, struct device *parent);
 void bsg_unregister_queue(struct request_queue *q);
 #else