linux-kernel - Re: [PATCH] 9p: disconnect channel when PCI device is removed

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Message-ID: <CA+1xoqfgA6DJL7ztMOdfLZedV6YwzZPUfbovFykdSSZy0Aio6w@mail.gmail.com>
Date:	Mon, 16 Apr 2012 06:35:47 +0200
From:	Sasha Levin <levinsasha928@...il.com>
To:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Cc:	davem@...emloft.net, ericvh@...il.com, jvrao@...ux.vnet.ibm.com,
	rusty@...tcorp.com.au, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, davej@...hat.com
Subject: Re: [PATCH] 9p: disconnect channel when PCI device is removed

On Sun, Apr 15, 2012 at 2:27 PM, Aneesh Kumar K.V
<aneesh.kumar@...ux.vnet.ibm.com> wrote:
> Sasha Levin <levinsasha928@...il.com> writes:
>
>> When a virtio_9p pci device is being removed, we should close down any
>> active channels and free up resources, we're not supposed to BUG() if there's
>> still an open channel since it's a valid case when removing the PCI device.
>>
>> Otherwise, removing the PCI device with an open channel would cause the
>> following BUG():
>>
> ...
>
>> diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
>> index 3d43206..5af18d1 100644
>> --- a/net/9p/trans_virtio.c
>> +++ b/net/9p/trans_virtio.c
>> @@ -615,7 +615,8 @@ static void p9_virtio_remove(struct virtio_device *vdev)
>>  {
>>       struct virtio_chan *chan = vdev->priv;
>>
>> -     BUG_ON(chan->inuse);
>> +     if (chan->inuse)
>> +             p9_virtio_close(chan->client);
>>       vdev->config->del_vqs(vdev);
>>
>>       mutex_lock(&virtio_9p_lock);
>
> But an umount should have resulted in p9_virtio_close ? How are you
> removing the device ? Are you removing the device with file system
> mounted  ?. In that case may be we should return EBUSY ?

I signal the underlying PCI device to remove (echo 1 >
/sys/devices/pci0000\:00/[...]/remove), we can't really prevent that
thing so we must clean up ourselves.
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