From 77c570a1ea85ba4ab135c61a028420a6e9fe77f3 Mon Sep 17 00:00:00 2001 From: Fanjun Kong Date: Tue, 17 May 2022 01:39:30 +0800 Subject: [PATCH] blk-cgroup: Remove unnecessary rcu_read_lock/unlock() 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 Reviewed-by: Muchun Song Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20220516173930.159535-1-bh1scw@gmail.com Signed-off-by: Jens Axboe --- 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 @@ err_destroy_all: return ret; err_unlock: spin_unlock_irq(&q->queue_lock); - rcu_read_unlock(); if (preloaded) radix_tree_preload_end(); return PTR_ERR(blkg);