From 76cffccd606acffde1b91e8b029b39b5fd1a3117 Mon Sep 17 00:00:00 2001 From: yangerkun Date: Sat, 19 Sep 2020 11:54:25 +0800 Subject: [PATCH] block-mq: fix comments in blk_mq_queue_tag_busy_iter 'f5bbbbe4d635 ("blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter")' introduce a bug what we may sleep between rcu lock. Then '530ca2c9bd69 ("blk-mq: Allow blocking queue tag iter callbacks")' fix it by get request_queue's ref. And 'a9a808084d6a ("block: Remove the synchronize_rcu() call from __blk_mq_update_nr_hw_queues()")' remove the synchronize_rcu in __blk_mq_update_nr_hw_queues. We need update the confused comments in blk_mq_queue_tag_busy_iter. Signed-off-by: yangerkun Signed-off-by: Jens Axboe --- block/blk-mq-tag.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index aacf10decdbd..9c92053e704d 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -416,9 +416,7 @@ void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, /* * __blk_mq_update_nr_hw_queues() updates nr_hw_queues and queue_hw_ctx * while the queue is frozen. So we can use q_usage_counter to avoid - * racing with it. __blk_mq_update_nr_hw_queues() uses - * synchronize_rcu() to ensure this function left the critical section - * below. + * racing with it. */ if (!percpu_ref_tryget(&q->q_usage_counter)) return;