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>
This commit is contained in:
Bart Van Assche 2018-01-17 11:48:09 -08:00 committed by Jens Axboe
parent 83d016ac86
commit 14a23498ba

View file

@ -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);