From: Fanjun Kong <bh1scw@gmail.com>
Date: Tue, 17 May 2022 01:39:30 +0800
Subject: [PATCH] blk-cgroup: Remove unnecessary rcu_read_lock/unlock()
Git-commit: 77c570a1ea85ba4ab135c61a028420a6e9fe77f3
Patch-mainline: v5.19-rc1
References: jsc#PED-1183
spin_lock_irq/spin_unlock_irq contains preempt_disable/enable().
Which can serve as RCU read-side critical region, so remove
rcu_read_lock/unlock().
Signed-off-by: Fanjun Kong <bh1scw@gmail.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220516173930.159535-1-bh1scw@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
block/blk-cgroup.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 204442fad33c..0676cf7a41b5 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1278,14 +1278,13 @@ int blkcg_init_queue(struct request_queue *q)
preloaded = !radix_tree_preload(GFP_KERNEL);
/* Make sure the root blkg exists. */
- rcu_read_lock();
+ /* spin_lock_irq can serve as RCU read-side critical section. */
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;
spin_unlock_irq(&q->queue_lock);
- rcu_read_unlock();
if (preloaded)
radix_tree_preload_end();
@@ -1311,7 +1310,6 @@ int blkcg_init_queue(struct request_queue *q)
return ret;
err_unlock:
spin_unlock_irq(&q->queue_lock);
- rcu_read_unlock();
if (preloaded)
radix_tree_preload_end();
return PTR_ERR(blkg);
--
2.35.3