Commit 14a23498 authored by Bart Van Assche's avatar Bart Van Assche Committed by Jens Axboe
Browse files

block: Document scheduler modification locking requirements 



This patch does not change any functionality.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarBart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 83d016ac

block/elevator.c

+8 −0
Original line number Diff line number Diff line
@@ -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);