From eebc21d12f56c1e09a163abf91e351fa2a55a938 Mon Sep 17 00:00:00 2001
From: Yu Kuai <yukuai3@huawei.com>
Date: Sat, 27 May 2023 09:06:43 +0800
Subject: [PATCH] blk-iocost: move wbt_enable/disable_default() out of spinlock
There are following smatch warning:
block/blk-wbt.c:843 wbt_init() warn: sleeping in atomic context
ioc_qos_write() <- disables preempt
-> wbt_enable_default()
-> wbt_init()
wbt_init() will be called from wbt_enable_default() if wbt is not
initialized, currently this is only possible in blk_register_queue(), hence
wbt_init() will never be called from iocost and this warning is false
positive.
However, we might support rq_qos destruction dynamically in the future,
and it's better to prevent that, hence move wbt_enable_default() outside
'ioc->lock'. This is safe because queue is still freezed.
Reported-by: Dan Carpenter <error27@gmail.com>
Link: https://lore.kernel.org/lkml/Y+Ja5SRs886CEz7a@kadam/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230527010644.647900-5-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
block/blk-iocost.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 6084a9519883e..9dfcf540f4001 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -3301,11 +3301,9 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
blk_stat_enable_accounting(disk->queue);
blk_queue_flag_set(QUEUE_FLAG_RQ_ALLOC_TIME, disk->queue);
ioc->enabled = true;
- wbt_disable_default(disk);
} else {
blk_queue_flag_clear(QUEUE_FLAG_RQ_ALLOC_TIME, disk->queue);
ioc->enabled = false;
- wbt_enable_default(disk);
}
if (user) {
@@ -3318,6 +3316,11 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
ioc_refresh_params(ioc, true);
spin_unlock_irq(&ioc->lock);
+ if (enable)
+ wbt_disable_default(disk);
+ else
+ wbt_enable_default(disk);
+
blk_mq_unquiesce_queue(disk->queue);
blk_mq_unfreeze_queue(disk->queue);
--
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