From 14a23498ba97683c6790b1bcd8b2cdfe9ad99797 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Wed, 17 Jan 2018 11:48:09 -0800 Subject: [PATCH] block: Document scheduler modification locking requirements This patch does not change any functionality. Reviewed-by: Christoph Hellwig Signed-off-by: Bart Van Assche Signed-off-by: Jens Axboe --- 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);