block: Document scheduler modification locking requirements
This patch does not change any functionality.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/elevator.c b/block/elevator.c
index 4f00b53..e87e9b4 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -869,6 +869,8 @@
struct elevator_queue *e = q->elevator;
int error;
+ lockdep_assert_held(&q->sysfs_lock);
+
error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched");
if (!error) {
struct elv_fs_entry *attr = e->type->elevator_attrs;
@@ -889,6 +891,8 @@
void elv_unregister_queue(struct request_queue *q)
{
+ lockdep_assert_held(&q->sysfs_lock);
+
if (q) {
struct elevator_queue *e = q->elevator;
@@ -965,6 +969,8 @@
{
int ret;
+ lockdep_assert_held(&q->sysfs_lock);
+
blk_mq_freeze_queue(q);
blk_mq_quiesce_queue(q);
@@ -1010,6 +1016,8 @@
bool old_registered = false;
int err;
+ lockdep_assert_held(&q->sysfs_lock);
+
if (q->mq_ops)
return elevator_switch_mq(q, new_e);