> @@ -185,31 +187,53 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
> goto err_free_blkg;
> }
>
> + if (drop_locks) {
> + spin_unlock_irq(q->queue_lock);
> + rcu_read_unlock();
> + }
I have a general dislike for code like that, where you conditionally
drop locks. And this one seems even worse, since the knowledge of
whether the locks should/could be dropped or not is embedded in the gfp
flags.
> +/**
> + * blkg_lookup_create - lookup blkg, try to create one if not there
> + *
> + * Performs an initial queue bypass check and then passes control to
> + * __blkg_lookup_create().
> + */
> +struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
> + struct request_queue *q, gfp_t gfp,
> + const struct blkcg_policy *pol)
> +{
> + WARN_ON_ONCE(!rcu_read_lock_held());
> + lockdep_assert_held(q->queue_lock);
This seems problematic, as blkcg_bio_issue_check() calls with the rcu
read lock held.
--
Jens Axboe
