Commit fcaa174a authored by Yu Kuai's avatar Yu Kuai Committed by Jens Axboe
Browse files

scsi/sg: don't grab scsi host module reference 



In order to prevent request_queue to be freed before cleaning up
blktrace debugfs entries, commit db59133e ("scsi: sg: fix blktrace
debugfs entries leakage") use scsi_device_get(), however,
scsi_device_get() will also grab scsi module reference and scsi module
can't be removed.

It's reported that blktests can't unload scsi_debug after block/001:

blktests (master) # ./check block
block/001 (stress device hotplugging) [failed]
     +++ /root/blktests/results/nodev/block/001.out.bad 2023-06-19
      Running block/001
      Stressing sd
     +modprobe: FATAL: Module scsi_debug is in use.

Fix this problem by grabbing request_queue reference directly, so that
scsi host module can still be unloaded while request_queue will be
pinged by sg device.

Reported-by: default avatarChaitanya Kulkarni <chaitanyak@nvidia.com>
Link: https://lore.kernel.org/all/1760da91-876d-fc9c-ab51-999a6f66ad50@nvidia.com/


Fixes: db59133e ("scsi: sg: fix blktrace debugfs entries leakage")
Signed-off-by: default avatarYu Kuai <yukuai3@huawei.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230621160111.1433521-1-yukuai1@huaweicloud.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent a42fb5a7

drivers/scsi/sg.c

+3 −3
Original line number Diff line number Diff line
@@ -1497,7 +1497,7 @@ sg_add_device(struct device *cl_dev) 
	int error;

	unsigned long iflags;



	error = scsi_device_get(scsidp);

	error = blk_get_queue(scsidp->request_queue);

	if (error)

		return error;
@@ -1558,7 +1558,7 @@ sg_add_device(struct device *cl_dev) 
out:

	if (cdev)

		cdev_del(cdev);

	scsi_device_put(scsidp);

	blk_put_queue(scsidp->request_queue);

	return error;

}
@@ -1575,7 +1575,7 @@ sg_device_destroy(struct kref *kref) 
	 */



	blk_trace_remove(q);

	scsi_device_put(sdp->device);

	blk_put_queue(q);



	write_lock_irqsave(&sg_index_lock, flags);

	idr_remove(&sg_index_idr, sdp->index);