[PATCH 04/11] block: Protect queue flag changes with the queue lock

Bart Van Assche
2018-02-28T19:28:25Z

Since the queue flags may be changed concurrently from multiple
contexts after a queue becomes visible in sysfs, make these changes
safe by protecting these with the queue lock.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
---
block/blk-mq.c | 3 +--
block/blk-stat.c | 6 +++---
2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 67026494119b..899f357962e8 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3022,8 +3022,7 @@ EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
/* Enable polling stats and return whether they were already enabled. */
static bool blk_poll_stats_enable(struct request_queue *q)
{
- if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
- test_and_set_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags))
+ if (blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS, q))
return true;
blk_stat_add_callback(q, q->poll_cb);
return false;
diff --git a/block/blk-stat.c b/block/blk-stat.c
index b664aa6df725..bd365a95fcf8 100644
--- a/block/blk-stat.c
+++ b/block/blk-stat.c
@@ -152,7 +152,7 @@ void blk_stat_add_callback(struct request_queue *q,

spin_lock(&q->stats->lock);
list_add_tail_rcu(&cb->list, &q->stats->callbacks);
- queue_flag_set(QUEUE_FLAG_STATS, q);
+ blk_queue_flag_set(QUEUE_FLAG_STATS, q);
spin_unlock(&q->stats->lock);
}
EXPORT_SYMBOL_GPL(blk_stat_add_callback);
@@ -163,7 +163,7 @@ void blk_stat_remove_callback(struct request_queue *q,
spin_lock(&q->stats->lock);
list_del_rcu(&cb->list);
if (list_empty(&q->stats->callbacks) && !q->stats->enable_accounting)
- queue_flag_clear(QUEUE_FLAG_STATS, q);
+ blk_queue_flag_clear(QUEUE_FLAG_STATS, q);
spin_unlock(&q->stats->lock);

del_timer_sync(&cb->timer);
@@ -191,7 +191,7 @@ void blk_stat_enable_accounting(struct request_queue *q)
{
spin_lock(&q->stats->lock);
q->stats->enable_accounting = true;
- queue_flag_set(QUEUE_FLAG_STATS, q);
+ blk_queue_flag_set(QUEUE_FLAG_STATS, q);
spin_unlock(&q->stats->lock);
}

--
2.16.2