From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Bart Van Assche To: Jens Axboe CC: , Bart Van Assche , Christoph Hellwig , Hannes Reinecke Subject: [PATCH v3 1/5] blk-mq: Make it safe to use RCU to iterate over blk_mq_tag_set.tag_list Date: Thu, 6 Apr 2017 11:10:46 -0700 Message-ID: <20170406181050.12137-2-bart.vanassche@sandisk.com> In-Reply-To: <20170406181050.12137-1-bart.vanassche@sandisk.com> References: <20170406181050.12137-1-bart.vanassche@sandisk.com> MIME-Version: 1.0 Content-Type: text/plain Return-Path: Bart.VanAssche@sandisk.com List-ID: Since the next patch in this series will use RCU to iterate over tag_list, make this safe. Add lockdep_assert_held() statements in functions that iterate over tag_list to make clear that using list_for_each_entry() instead of list_for_each_entry_rcu() is fine in these functions. Signed-off-by: Bart Van Assche Cc: Christoph Hellwig Cc: Hannes Reinecke --- block/blk-mq.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/block/blk-mq.c b/block/blk-mq.c index f7cd3208bcdf..b5580b09b4a5 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2076,6 +2076,8 @@ static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared) { struct request_queue *q; + lockdep_assert_held(&set->tag_list_lock); + list_for_each_entry(q, &set->tag_list, tag_set_list) { blk_mq_freeze_queue(q); queue_set_hctx_shared(q, shared); @@ -2096,6 +2098,8 @@ static void blk_mq_del_queue_tag_set(struct request_queue *q) blk_mq_update_tag_set_depth(set, false); } mutex_unlock(&set->tag_list_lock); + + synchronize_rcu(); } static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set, @@ -2601,6 +2605,8 @@ void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues) { struct request_queue *q; + lockdep_assert_held(&set->tag_list_lock); + if (nr_hw_queues > nr_cpu_ids) nr_hw_queues = nr_cpu_ids; if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues) -- 2.12.0