blkcg: init root blkcg_gq under lock
The initializing of q->root_blkg is currently outside of queue lock
and rcu, so the blkg may be destroied before the initializing, which
may cause dangling/null references. On the other side, the destroys
of blkg are protected by queue lock or rcu. Put the initializing
inside the queue lock and rcu to make it safer.
Signed-off-by: Jiang Biao <jiang.biao2@zte.com.cn>
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
CC: Tejun Heo <tj@kernel.org>
CC: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 79da2a7..eb85cb8 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1181,18 +1181,16 @@
rcu_read_lock();
spin_lock_irq(q->queue_lock);
blkg = blkg_create(&blkcg_root, q, new_blkg);
+ if (IS_ERR(blkg))
+ goto err_unlock;
+ q->root_blkg = blkg;
+ q->root_rl.blkg = blkg;
spin_unlock_irq(q->queue_lock);
rcu_read_unlock();
if (preloaded)
radix_tree_preload_end();
- if (IS_ERR(blkg))
- return PTR_ERR(blkg);
-
- q->root_blkg = blkg;
- q->root_rl.blkg = blkg;
-
ret = blk_throtl_init(q);
if (ret) {
spin_lock_irq(q->queue_lock);
@@ -1200,6 +1198,13 @@
spin_unlock_irq(q->queue_lock);
}
return ret;
+
+err_unlock:
+ spin_unlock_irq(q->queue_lock);
+ rcu_read_unlock();
+ if (preloaded)
+ radix_tree_preload_end();
+ return PTR_ERR(blkg);
}
/**