diff options
author | Jianchao Wang <jianchao.w.wang@oracle.com> | 2018-08-21 15:15:04 +0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-04-13 10:32:52 +0200 |
commit | f530afb974c2e82047bd6220303a2dbe30eff304 (patch) | |
tree | 5218518520e31fee7c0840aaa3d0cb882b64e7da /block/blk-mq.c | |
parent | 4eaf2e4b5e1e50aa4debf08b2875b574f56ff1e9 (diff) |
blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter
commit f5bbbbe4d63577026f908a809f22f5fd5a90ea1f upstream.
For blk-mq, part_in_flight/rw will invoke blk_mq_in_flight/rw to
account the inflight requests. It will access the queue_hw_ctx and
nr_hw_queues w/o any protection. When updating nr_hw_queues and
blk_mq_in_flight/rw occur concurrently, panic comes up.
Before update nr_hw_queues, the q will be frozen. So we could use
q_usage_counter to avoid the race. percpu_ref_is_zero is used here
so that we will not miss any in-flight request. The access to
nr_hw_queues and queue_hw_ctx in blk_mq_queue_tag_busy_iter are
under rcu critical section, __blk_mq_update_nr_hw_queues could use
synchronize_rcu to ensure the zeroed q_usage_counter to be globally
visible.
Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Cc: Giuliano Procida <gprocida@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'block/blk-mq.c')
-rw-r--r-- | block/blk-mq.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index 24fc09cf7f17..58be2eaa5aaa 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2346,6 +2346,10 @@ void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues) list_for_each_entry(q, &set->tag_list, tag_set_list) blk_mq_unfreeze_queue(q); + /* + * Sync with blk_mq_queue_tag_busy_iter. + */ + synchronize_rcu(); } EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues); |