blk-mq: don't hold q->sysfs_lock in blk_mq_map_swqueue
authorMing Lei <ming.lei@redhat.com>
Tue, 27 Aug 2019 11:01:46 +0000 (19:01 +0800)
committerJens Axboe <axboe@kernel.dk>
Tue, 27 Aug 2019 16:40:20 +0000 (10:40 -0600)
commitc6ba933358f0d7a6a042b894dba20cc70396a6d3
treee5d7c3e7fadb316f744edc706a3b8df14a4157aa
parentc48dac137a62a5d6fa1ef3fa445cbd9c43655a76
blk-mq: don't hold q->sysfs_lock in blk_mq_map_swqueue

blk_mq_map_swqueue() is called from blk_mq_init_allocated_queue()
and blk_mq_update_nr_hw_queues(). For the former caller, the kobject
isn't exposed to userspace yet. For the latter caller, hctx sysfs entries
and debugfs are un-registered before updating nr_hw_queues.

On the other hand, commit 2f8f1336a48b ("blk-mq: always free hctx after
request queue is freed") moves freeing hctx into queue's release
handler, so there won't be race with queue release path too.

So don't hold q->sysfs_lock in blk_mq_map_swqueue().

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block/blk-mq.c