Hi, In the current implementation we use q->sysfs_dir_lock for protecting kobject addition/deletion while we register/unregister blk-mq with sysfs. However the sysfs/kernfs internal implementation already protects against the simultaneous addtion/deletion of kobjects. So in that sense use of q->sysfs_dir_lock appears redundant. Furthermore, there're few other callsites in the current code where we use q->sysfs_dir_lock along with q->sysfs_lock while addition/deletion of independent access ranges for a disk under sysfs. Please refer, disk_ register_independent_access_ranges() and disk_unregister_independent_ access_ranges(). Here as well we could easily remove use of q->sysfs_dir_ lock. The only thing which q->syfs_dir_lock appears to protect is the use of variable q->mq_sysfs_init_done. However this could be solved by converting q->mq_sysfs_init_done to an atomic variable. In past few days, we have seen many lockdep splat in block layer and getting rid of this one might help reduce some contention as well we need to worry less about lock ordering wrt to this lock. Nilay Shroff (1): block: get rid of request queue ->sysfs_dir_lock block/blk-core.c | 1 - block/blk-ia-ranges.c | 4 ---- block/blk-mq-sysfs.c | 25 +++++++------------------ block/blk-sysfs.c | 5 ----- include/linux/blkdev.h | 3 +-- 5 files changed, 8 insertions(+), 30 deletions(-) -- 2.47.1
