linux-kernel - Re: [PATCH] scsi: sd: call device_del() if device_add

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Message-ID: <YkVwt4s+K0haRpbr@infradead.org>
Date:   Thu, 31 Mar 2022 02:13:27 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>
Cc:     Dan Carpenter <dan.carpenter@...cle.com>,
        Christoph Hellwig <hch@...radead.org>,
        Wenchao Hao <haowenchao@...wei.com>, axboe@...nel.dk,
        jejb@...ux.ibm.com, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
        martin.petersen@...cle.com,
        syzbot+f08c77040fa163a75a46@...kaller.appspotmail.com,
        syzkaller-bugs@...glegroups.com, linfeilong@...wei.com
Subject: Re: [PATCH] scsi: sd: call device_del() if device_add_disk() fails

On Thu, Mar 31, 2022 at 11:07:45AM +0200, Fabio M. De Francesco wrote:
> If I don't misunderstand what you wrote, I think you mean something like
> the following changes:
> 
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index a390679cf458..7a000a9a9dbe 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -3431,7 +3431,7 @@ static int sd_probe(struct device *dev)
>         sdkp->disk_dev.class = &sd_disk_class;
>         dev_set_name(&sdkp->disk_dev, "%s", dev_name(dev));
>  
> -       error = device_add(&sdkp->disk_dev);
> +       error = device_register(&sdkp->disk_dev);

The device_initialize call about also need to go.

>         if (error) {
>                 put_device(&sdkp->disk_dev);

.. and this put_device

>                 goto out;
> @@ -3474,7 +3474,7 @@ static int sd_probe(struct device *dev)
>  
>         error = device_add_disk(dev, gd, NULL);
>         if (error) {
> -               put_device(&sdkp->disk_dev);
> +               device_unregister(&sdkp->disk_dev);
>                 goto out;
>         }

.. and then the cleanup patch would need the same logic.  But thinking
about it I don't think we actually can do that due to the split
unregistration.  So I take my suggestion back.