linux-kernel - Re: [PATCH v2 1/2] virt: vbox: Add check for device_create

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Date:   Thu, 1 Sep 2022 11:39:46 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Jiasheng Jiang <jiasheng@...as.ac.cn>
Cc:     hdegoede@...hat.com, arnd@...db.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] virt: vbox: Add check for device_create_file

On Thu, Sep 01, 2022 at 05:17:52PM +0800, Jiasheng Jiang wrote:
> As device_create_file() can return error number,
> it should be better to check the return value and
> deal with the exception.
> Moreover, this driver should be using an attribute group.
> 
> Fixes: 0ba002bc4393 ("virt: Add vboxguest driver for Virtual Box Guest integration")
> Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
> ---
> Change log:
> 
> v1 -> v2:
> 
> 1. Use gdev->dev instead of dev.
> 2. Remove file when creation failed.
> ---
>  drivers/virt/vboxguest/vboxguest_linux.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/virt/vboxguest/vboxguest_linux.c b/drivers/virt/vboxguest/vboxguest_linux.c
> index 4ccfd30c2a30..2fb9a6d91b53 100644
> --- a/drivers/virt/vboxguest/vboxguest_linux.c
> +++ b/drivers/virt/vboxguest/vboxguest_linux.c
> @@ -390,8 +390,13 @@ static int vbg_pci_probe(struct pci_dev *pci, const struct pci_device_id *id)
>  	}
>  
>  	pci_set_drvdata(pci, gdev);
> -	device_create_file(dev, &dev_attr_host_version);
> -	device_create_file(dev, &dev_attr_host_features);
> +
> +	ret = device_create_file(gdev->dev, &dev_attr_host_features);
> +	if (ret)
> +		goto err_unregister_misc_device_user;
> +	ret = device_create_file(gdev->dev, &dev_attr_host_version);
> +	if (ret)
> +		goto err_remove_file_features;
>  
>  	vbg_info("vboxguest: misc device minor %d, IRQ %d, I/O port %x, MMIO at %pap (size %pap)\n",
>  		 gdev->misc_device.minor, pci->irq, gdev->io_port,
> @@ -399,6 +404,8 @@ static int vbg_pci_probe(struct pci_dev *pci, const struct pci_device_id *id)
>  
>  	return 0;
>  
> +err_remove_file_features:
> +	device_remove_file(gdev->dev, &dev_attr_host_features);
>  err_unregister_misc_device_user:
>  	misc_deregister(&gdev->misc_device_user);
>  err_unregister_misc_device:
> -- 
> 2.25.1
> 

Please make a patch series that is linked together, the one you just did
was not properly threaded at all (hint, use git send-email).

And again, this is not the correct way to solve this issue, use a
default attribute group for the driver instead.  No driver should ever
be adding or removing files individually like this.

thanks,

greg k-h