From: Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH] virtio: make PCI devices take a virtio_pci module ref
Date: Sun, 7 Dec 2008 19:00:08 +1030
Message-ID: <200812071900.08987.rusty@rustcorp.com.au>
References: <1228394671.3732.77.camel@blaa> <4938EE0B.8020501@msgid.tls.msk.ru> <493929D2.4070900@gmail.com>
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Cc: Michael Tokarev <mjt@tls.msk.ru>,
	Mark McLoughlin <markmc@redhat.com>,
	"linux-kernel" <linux-kernel@vger.kernel.org>,
	kvm <kvm@vger.kernel.org>, Anthony Liguori <aliguori@us.ibm.com>,
	Greg KH <gregkh@suse.de>
To: Jiri Slaby <jirislaby@gmail.com>
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On Friday 05 December 2008 23:47:06 Jiri Slaby wrote:
> Michael Tokarev napsal(a):
> > Jiri Slaby wrote:
> >> On 12/04/2008 01:44 PM, Mark McLoughlin wrote:
> >>> Nothing takes a ref on virtio_pci, so even if you have
> >>> devices in use, rmmod will attempt to unload the module.
> >> It unbinds the device properly as any other driver. So what's the problem here?
> > 
> > Here's what we get when rmmod'ing (a zero-refcounted but
> > in use) virtio_pci (I did it by a chance, cut-n-pasted
> > the wrong line):
> > 
> > WARNING: at drivers/base/core.c:122 device_release+0x5f/0x70()
> > Device 'virtio1' does not have a release() function, it is broken and must be fixed.
> > Modules linked in: ext3 jbd mbcache acpiphp dock pci_hotplug virtio_net virtio_blk virtio_pci(-) virtio_ring virtio
> > 
> > Pid: 361, comm: rmmod Tainted: G S        2.6.27-i686smp #2.6.27.7
> >  [<c012b81f>] warn_slowpath+0x6f/0xa0
> >  [<c0110030>] prepare_set+0x30/0x80
> >  [<c012067e>] __wake_up+0x3e/0x60
> >  [<c01d1d25>] release_sysfs_dirent+0x45/0xb0
> >  ...
> 
> So why don't you fix the root cause and add such a crap into the probe
> function (not even counting probe can fail later)?
> 
> Fix the virtio bus instead.

Incoherent? CHECK
Rude to bug reporter? CHECK
Unhelpful? CHECK

Wow, you must be a *great* kernel maintainer!

Thanks for making us all so very, very proud.
Rusty.