blk-mq: exit the hctxs of a queue under tag_list_lock

blk_mq_update_nr_hw_queues() exits and replaces the hctxs of every queue
on set->tag_list under tag_list_lock. blk_mq_exit_queue() exits its
hctxs without the lock and only then takes the queue off the list, so an
update running at the same time exits them again and sets up new ones
that nobody exits. del_gendisk() is kept away by update_nr_hwq_lock,
disk_release() of a never added disk and blk_mq_destroy_queue() are not,
and nvme_alloc_ns() drops such a disk when it finds the queues frozen by
a reset.

Hold tag_list_lock for both steps.

Fixes: 630ef623ed26 ("blk-mq: Swap two calls in blk_mq_exit_queue()")
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Link: https://patch.msgid.link/20261028164415.1262013-38-axboe@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>

0 files changed, 0 insertions, 0 deletions