[PATCH v2 2/3] block: Document scheduler modification locking requirements

Bart Van Assche
2018-01-17T19:48:09Z

This patch does not change any functionality.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
---
block/elevator.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/block/elevator.c b/block/elevator.c
index 4f00b53cd5fd..e87e9b43aba0 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -869,6 +869,8 @@ int elv_register_queue(struct request_queue *q)
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 @@ int elv_register_queue(struct request_queue *q)

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 @@ static int elevator_switch_mq(struct request_queue *q,
{
int ret;

+ lockdep_assert_held(&q->sysfs_lock);
+
blk_mq_freeze_queue(q);
blk_mq_quiesce_queue(q);

@@ -1010,6 +1016,8 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
bool old_registered = false;
int err;

+ lockdep_assert_held(&q->sysfs_lock);
+
if (q->mq_ops)
return elevator_switch_mq(q, new_e);

--
2.15.1