diff options
| -rw-r--r-- | block/blk-cgroup.c | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 342816cbbd1b..ee076ab795d3 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -136,6 +136,11 @@ static void blkg_free_workfn(struct work_struct *work) spin_unlock_irq(&q->queue_lock); mutex_unlock(&q->blkcg_mutex); + /* + * Release blkcg css ref only after blkg is removed from q->blkg_list, + * so concurrent iterators won't see a blkg with a freed blkcg. + */ + css_put(&blkg->blkcg->css); blk_put_queue(q); free_percpu(blkg->iostat_cpu); percpu_ref_exit(&blkg->refcnt); @@ -169,8 +174,6 @@ static void __blkg_release(struct rcu_head *rcu) WARN_ON(!bio_list_empty(&blkg->async_bios)); #endif - /* release the blkcg and parent blkg refs this blkg has been holding */ - css_put(&blkg->blkcg->css); blkg_free(blkg); } @@ -314,6 +317,9 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct gendisk *disk, goto out_exit_refcnt; if (!blk_get_queue(disk->queue)) goto out_free_iostat; + /* blkg holds a reference to blkcg */ + if (!css_tryget_online(&blkcg->css)) + goto out_put_queue; blkg->q = disk->queue; INIT_LIST_HEAD(&blkg->q_node); @@ -354,6 +360,8 @@ out_free_pds: while (--i >= 0) if (blkg->pd[i]) blkcg_policy[i]->pd_free_fn(blkg->pd[i]); + css_put(&blkcg->css); +out_put_queue: blk_put_queue(disk->queue); out_free_iostat: free_percpu(blkg->iostat_cpu); @@ -382,18 +390,12 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, struct gendisk *disk, goto err_free_blkg; } - /* blkg holds a reference to blkcg */ - if (!css_tryget_online(&blkcg->css)) { - ret = -ENODEV; - goto err_free_blkg; - } - /* allocate */ if (!new_blkg) { new_blkg = blkg_alloc(blkcg, disk, GFP_NOWAIT); if (unlikely(!new_blkg)) { ret = -ENOMEM; - goto err_put_css; + goto err_free_blkg; } } blkg = new_blkg; @@ -403,7 +405,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, struct gendisk *disk, blkg->parent = blkg_lookup(blkcg_parent(blkcg), disk->queue); if (WARN_ON_ONCE(!blkg->parent)) { ret = -ENODEV; - goto err_put_css; + goto err_free_blkg; } blkg_get(blkg->parent); } @@ -443,8 +445,6 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, struct gendisk *disk, blkg_put(blkg); return ERR_PTR(ret); -err_put_css: - css_put(&blkcg->css); err_free_blkg: if (new_blkg) blkg_free(new_blkg); |