From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jiri Slaby <jirislaby@gmail.com>
Subject: Re: [PATCH] virtio: make PCI devices take a virtio_pci module ref
Date: Fri, 05 Dec 2008 16:25:31 +0100
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Cc: Michael Tokarev <mjt@tls.msk.ru>,
	Rusty Russell <rusty@rustcorp.com.au>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	kvm <kvm@vger.kernel.org>, Anthony Liguori <aliguori@us.ibm.com>,
	Greg KH <gregkh@suse.de>
To: Mark McLoughlin <markmc@redhat.com>
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Mark McLoughlin wrote:
>> Fix the virtio bus instead.
> 
> Yeah, the patch I posted wasn't meant as a fix for this traceback.

So what's the module_get patch needed for?

> Here's one that does fix it.
...
> From: Mark McLoughlin <markmc@redhat.com>
> Subject: [PATCH] virtio: add device release() function
> 
> Add a release() function for virtio_pci devices so as to avoid:
> 
>   Device 'virtio0' does not have a release() function, it is broken and must be fixed
> 
> The struct device is embedded in the struct virtio_pci_device which
> is freed by virtio_pci_remove(), so virtio_pci_release_dev() need
> not actually do anything.
> 
> Signed-off-by: Mark McLoughlin <markmc@redhat.com>
> ---
>  drivers/virtio/virtio_pci.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
> index c7dc37c..7d4899c 100644
> --- a/drivers/virtio/virtio_pci.c
> +++ b/drivers/virtio/virtio_pci.c
> @@ -70,12 +70,17 @@ static struct pci_device_id virtio_pci_id_table[] = {
>  
>  MODULE_DEVICE_TABLE(pci, virtio_pci_id_table);
>  
> +static void virtio_pci_release_dev(struct device *dev)
> +{
> +}

You have to have a strong reason to have empty release. This is not the
case, you should do the free here, not in remove, I suppose.

> @@ -328,6 +333,7 @@ static int __devinit virtio_pci_probe(struct pci_dev *pci_dev,
>  		return -ENOMEM;
>  
>  	vp_dev->vdev.dev.parent = &virtio_pci_root;
> +	vp_dev->vdev.dev.release = virtio_pci_release_dev;

This should rather be in register_virtio_device