linux-kernel - Re: [PATCH] block: add put_device() call when device_add() fails in device_add

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Message-ID: <bf8659c5-8cfe-fd0e-3b59-c07cf1f48a87@huaweicloud.com>
Date: Thu, 22 Feb 2024 17:22:20 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Alfredo Cruz <alfredo.carlon@...il.com>, axboe@...nel.dk,
 linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
 "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH] block: add put_device() call when device_add() fails in
 device_add_disk()

Hi,

在 2024/02/22 6:01, Alfredo Cruz 写道:
> When device_add() fails, put_device() should called for cleanup.
> Added this call before the jump to out_free_ext_minor to not
> interfere with device_del() on error paths where deivce_add() succeeded
> 
> Signed-off-by: Alfredo Cruz <alfredo.carlon@...il.com>
> ---
>   block/genhd.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/block/genhd.c b/block/genhd.c
> index d74fb5b4ae68..5a231fb075bd 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -456,8 +456,10 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
>   	if (!(disk->flags & GENHD_FL_HIDDEN))
>   		ddev->devt = MKDEV(disk->major, disk->first_minor);
>   	ret = device_add(ddev);
> -	if (ret)
> +	if (ret) {
> +		put_device(ddev);
>   		goto out_free_ext_minor;
> +	}

This is wrong, gendisk is allocated by caller, and caller is responsible
to free the gendisk, as you can see in many callers.

Thanks,
Kuai

>   
>   	ret = disk_alloc_events(disk);
>   	if (ret)
>