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Commit a8f286bf authored by Jan Höppner's avatar Jan Höppner Committed by Greg Kroah-Hartman
Browse files

s390/dasd: Use correct lock while counting channel queue length 



[ Upstream commit ccc45cb4e7271c74dbb27776ae8f73d84557f5c6 ]

The lock around counting the channel queue length in the BIODASDINFO
ioctl was incorrectly changed to the dasd_block->queue_lock with commit
583d6535 ("dasd: remove dead code"). This can lead to endless list
iterations and a subsequent crash.

The queue_lock is supposed to be used only for queue lists belonging to
dasd_block. For dasd_device related queue lists the ccwdev lock must be
used.

Fix the mentioned issues by correctly using the ccwdev lock instead of
the queue lock.

Fixes: 583d6535 ("dasd: remove dead code")
Cc: stable@vger.kernel.org # v5.0+
Signed-off-by: default avatarJan Höppner <hoeppner@linux.ibm.com>
Reviewed-by: default avatarStefan Haberland <sth@linux.ibm.com>
Signed-off-by: default avatarStefan Haberland <sth@linux.ibm.com>
Link: https://lore.kernel.org/r/20230609153750.1258763-2-sth@linux.ibm.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent d60be47f

drivers/s390/block/dasd_ioctl.c

+2 −2
Original line number Diff line number Diff line
@@ -509,10 +509,10 @@ static int __dasd_ioctl_information(struct dasd_block *block, 


	memcpy(dasd_info->type, base->discipline->name, 4);



	spin_lock_irqsave(&block->queue_lock, flags);

	spin_lock_irqsave(get_ccwdev_lock(base->cdev), flags);

	list_for_each(l, &base->ccw_queue)

		dasd_info->chanq_len++;

	spin_unlock_irqrestore(&block->queue_lock, flags);

	spin_unlock_irqrestore(get_ccwdev_lock(base->cdev), flags);

	return 0;

}