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Subject: Re: [PATCH] blk-mq: only unregister sysfs when registration succeeded
To:     Liu Shixin <liushixin2@huawei.com>, Jens Axboe <axboe@kernel.dk>
Cc:     linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        "yukuai (C)" <yukuai3@huawei.com>
References: <20221112110754.1109979-1-liushixin2@huawei.com>
From:   Yu Kuai <yukuai1@huaweicloud.com>
Message-ID: <607beb5b-8d54-b795-8a05-76352d7ed863@huaweicloud.com>
Date:   Sat, 12 Nov 2022 18:44:37 +0800
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Hi,

?? 2022/11/12 19:07, Liu Shixin д??:
> kobject_del() must not be called if kobject_add() has not been called.
> Hence only unregister sysfs when registration succeeded.
> 

 From what I see, the blk_queue_registered() from caller
blk_unregister_queue() can already prevent that. QUEUE_FLAG_REGISTERED
will only be set if blk_register_queue() succeed.

Thanks,
Kuai

> Signed-off-by: Liu Shixin <liushixin2@huawei.com>
> ---
>   block/blk-mq-sysfs.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
> index 93997d297d42..63f2df2500d9 100644
> --- a/block/blk-mq-sysfs.c
> +++ b/block/blk-mq-sysfs.c
> @@ -279,6 +279,8 @@ void blk_mq_sysfs_unregister(struct gendisk *disk)
>   	unsigned long i;
>   
>   	lockdep_assert_held(&q->sysfs_dir_lock);
> +	if (!q->mq_sysfs_init_done)
> +		return;
>   
>   	queue_for_each_hw_ctx(q, hctx, i)
>   		blk_mq_unregister_hctx(hctx);
>