From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754767Ab2D1SQl (ORCPT ); Sat, 28 Apr 2012 14:16:41 -0400 Received: from e23smtp05.au.ibm.com ([202.81.31.147]:39574 "EHLO e23smtp05.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753495Ab2D1SQj convert rfc822-to-8bit (ORCPT ); Sat, 28 Apr 2012 14:16:39 -0400 From: "Aneesh Kumar K.V" To: Sasha Levin Cc: davem@davemloft.net, ericvh@gmail.com, jvrao@linux.vnet.ibm.com, rusty@rustcorp.com.au, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, davej@redhat.com Subject: Re: [PATCH] 9p: disconnect channel when PCI device is removed In-Reply-To: References: <1334353716-19483-1-git-send-email-levinsasha928@gmail.com> <87iph118pd.fsf@skywalker.in.ibm.com> <87ehrodjt6.fsf@skywalker.in.ibm.com> User-Agent: Notmuch/0.11.1+346~g13d19c3 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-pc-linux-gnu) Date: Sat, 28 Apr 2012 23:46:26 +0530 Message-ID: <87d36rafid.fsf@skywalker.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT x-cbid: 12042808-1396-0000-0000-0000010F645D Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sasha Levin writes: > On Mon, Apr 16, 2012 at 12:59 PM, Aneesh Kumar K.V > wrote: >> Sasha Levin writes: >> >>> On Sun, Apr 15, 2012 at 2:27 PM, Aneesh Kumar K.V >>> wrote: >>>> Sasha Levin 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. >> >> What does that mean for the mounted file system ? What would happen to >> the pending fs operations in that case ? > > I'm guessing that all of them should be canceled. Pending operation we can cancel, but what about dirty pages in cached mode ? Also how does virtio-blk handle this ? > virtio-pci simulates > a PCI device, if the PCI device is unplugged there's not much to do > about the filesystem or pending requests. Ideal thing to do would be to make remove return -EBUSY; let the user umount. But looking at the code, I guess there is no easy way to return error from remove callback ? -aneesh