block: move hctx cpuhp add/del out of queue freezing

JIRA: https://issues.redhat.com/browse/RHEL-106845

commit 7ed7fa5
Author: Ming Lei <ming.lei@redhat.com>
Date:   Mon May 5 22:18:02 2025 +0800

    block: move hctx cpuhp add/del out of queue freezing

    Move hctx cpuhp add/del out of queue freezing for not connecting freeze
    lock with cpuhp locks, then lockdep warning can be avoided.

    This way is safe because both needn't queue to be frozen and scheduler
    switch isn't allowed, with same reason for moving hctx debugfs/sysfs
    register out of queue freeze.

    Reviewed-by: Hannes Reinecke <hare@suse.de>
    Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
    Signed-off-by: Ming Lei <ming.lei@redhat.com>
    Reviewed-by: Christoph Hellwig <hch@lst.de>
    Link: https://lore.kernel.org/r/20250505141805.2751237-25-ming.lei@redhat.com
    Signed-off-by: Jens Axboe <axboe@kernel.dk>

Signed-off-by: Ming Lei <ming.lei@redhat.com>

Author: Ming Lei

block/blk-mq.c

@@ -5008,7 +5008,7 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
 fallback:
 	blk_mq_update_queue_map(set);
 	list_for_each_entry(q, &set->tag_list, tag_set_list) {
-		blk_mq_realloc_hw_ctxs(set, q);
+		__blk_mq_realloc_hw_ctxs(set, q);
 
 		if (q->nr_hw_queues != set->nr_hw_queues) {
 			int i = prev_nr_hw_queues;
@@ -5032,6 +5032,9 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
 	list_for_each_entry(q, &set->tag_list, tag_set_list) {
 		blk_mq_sysfs_register_hctxs(q);
 		blk_mq_debugfs_register_hctxs(q);
+
+		blk_mq_remove_hw_queues_cpuhp(q);
+		blk_mq_add_hw_queues_cpuhp(q);
 	}
 	memalloc_noio_restore(memflags);