From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Vrabel <david.vrabel@citrix.com>
Subject: Re: netback Oops then xenwatch stuck in D state
Date: Thu, 14 Feb 2013 12:20:43 +0000
Message-ID: <511CD69B.6050900@citrix.com>
References: <510C3AA3.2090508@theshore.net>	<CAOsiSVVyNU8GiJZ1km805nL3+UrrE-4J1Wo_UKjMvOiyzpr-xw@mail.gmail.com>	<50E3A390-C52B-476A-8B20-BADBA42F3775@theshore.net>	<51181924.4050500@theshore.net>	<1360583103.16636.29.camel@zion.uk.xensource.com>	<1360663133.20449.123.camel@zakaz.uk.xensource.com>	<511AFFC9.3050404@theshore.net>	<1360779868.16636.92.camel@zion.uk.xensource.com>	<1360780669.16636.94.camel@zion.uk.xensource.com>	<511BE780.9000707@cantab.net>	<20130213201725.GA1453@zion.uk.xensource.com>	<511CB86702000078000BE1C5@nat28.tlf.novell.com>	<1360840843.16636.109.camel@zion.uk.xensource.com>
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To: Jan Beulich <JBeulich@suse.com>
Cc: Wei Liu <wei.liu2@citrix.com>, Ian Campbell <Ian.Campbell@citrix.com>, "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
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On 14/02/13 11:48, Jan Beulich wrote:
>>>> On 14.02.13 at 12:20, Wei Liu <wei.liu2@citrix.com> wrote:
> 
>> If this is a bug, and, if my previous patch fixes Christopher's OOPS, he
>> will hit this bug soon when shutting down DomU.
> 
> I don't think this patch will fix his problems, which - as described
> yesterday - I'm relatively certain result from the harsh action
> netbk_fatal_tx_err() does.

I can't see anything broken in netbk_fatal_tx_err().

However, a call to netbk_fatal_tx_err() may result in the vif's ref
count going to 1 which means a simutaneous attempt to shutdown the vif
will free the net device.

Netback thread              Xenwatch thread

netbk_fatal_tx_err()        netback_remove()
                              xenvif_disconnect()
                                ...
                                free_netdev()
netbk_tx_err() Oops!

David