Messages in this thread | | | Subject | Re: [PATCH] blkcg: handle dying request_queue when associating a blkg | From | Bart Van Assche <> | Date | Tue, 11 Dec 2018 15:16:13 -0800 |
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On Tue, 2018-12-11 at 18:03 -0500, Dennis Zhou wrote: > diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c > index 6bd0619a7d6e..c30661ddc873 100644 > --- a/block/blk-cgroup.c > +++ b/block/blk-cgroup.c > @@ -202,6 +202,12 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, > WARN_ON_ONCE(!rcu_read_lock_held()); > lockdep_assert_held(&q->queue_lock); > > + /* request_queue is dying, do not create/recreate a blkg */ > + if (blk_queue_dying(q)) { > + ret = -ENODEV; > + goto err_free_blkg; > + } > + > /* blkg holds a reference to blkcg */ > if (!css_tryget_online(&blkcg->css)) { > ret = -ENODEV;
What prevents that the queue state changes after blk_queue_dying() has returned and before blkg_create() returns? Are you sure you don't need to protect this code with a blk_queue_enter() / blk_queue_exit() pair?
Bart.
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