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| author | Bart Van Assche <bart.vanassche@sandisk.com> | 2017-04-07 11:16:49 -0700 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2017-04-07 12:45:47 -0600 |
| commit | 705cda97ee3abb6ea38d651b54f4da83c2bb2a4a (patch) | |
| tree | fdc8eae0529160e721890e586080ae4d40163d7a /block/blk-mq.c | |
| parent | d945a365a0686a37618503622954f8dc169b8bca (diff) | |
| download | lwn-705cda97ee3abb6ea38d651b54f4da83c2bb2a4a.tar.gz lwn-705cda97ee3abb6ea38d651b54f4da83c2bb2a4a.zip | |
blk-mq: Make it safe to use RCU to iterate over blk_mq_tag_set.tag_list
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 <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/blk-mq.c')
| -rw-r--r-- | block/blk-mq.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index 9bdfeed59d9d..ad057fe572a4 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2111,6 +2111,8 @@ 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); @@ -2123,7 +2125,8 @@ static void blk_mq_del_queue_tag_set(struct request_queue *q) struct blk_mq_tag_set *set = q->tag_set; mutex_lock(&set->tag_list_lock); - list_del_init(&q->tag_set_list); + list_del_rcu(&q->tag_set_list); + INIT_LIST_HEAD(&q->tag_set_list); if (list_is_singular(&set->tag_list)) { /* just transitioned to unshared */ set->flags &= ~BLK_MQ_F_TAG_SHARED; @@ -2131,6 +2134,8 @@ 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, @@ -2148,7 +2153,7 @@ static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set, } if (set->flags & BLK_MQ_F_TAG_SHARED) queue_set_hctx_shared(q, true); - list_add_tail(&q->tag_set_list, &set->tag_list); + list_add_tail_rcu(&q->tag_set_list, &set->tag_list); mutex_unlock(&set->tag_list_lock); } @@ -2639,6 +2644,8 @@ 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) |