Hi Jens
Currently, the kobject_del for sysfs mq and hctx entry is invoked
under q->sysfs_lock. lock inversion will came up when someone try
to access the sysfs entries concurrently. The scenario is as below:
hold q->sysfs_lock access mq,hctx sysfs entries
kobject_del
__kernfs_remove kernfs_get_active
kernfs_drain
wait kn->active require q->sysfs_lock
To avoid this issue, kobject_del for mq and hctx sysfs entries
mustn't be inovked under sysfs_lock. These patch set is to achieve this.
1st patch introduces blk_queue_registered to test QUEUE_FLAG_REGISTERED
2nd patch remove blk_mq_register_dev which is usesless.
3rd patch fix the issue by changing the sync method, please refer to the
comment.
Jianchao Wang (3)
block: add helper interface blk_queue_registered
blk-mq: cleanup blk_mq_register_dev
block: fix the lock inversion caused by kobject_del under sysfs_lock
block/blk-mq-sysfs.c | 80 +++++++++++++++++++++++++++++++-------------------
block/blk-mq.h | 3 ++
block/blk-sysfs.c | 43 ++++++++++++++-------------
block/blk-wbt.c | 4 ---
block/elevator.c | 5 ++--
include/linux/blk-mq.h | 3 --
include/linux/blkdev.h | 4 ++-
7 files changed, 82 insertions(+), 60 deletions(-)
Thanks
Jianchao
