From: David Vrabel <david.vrabel@citrix.com>
Date: Thu, 14 Feb 2013 03:18:57 +0000 (+0000)
Subject: xen-netback: correctly return errors from netbk_count_requests()
X-Git-Tag: v3.2.40~31
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=aa067cfc66595a3a842ef56a9211a674ee136422;p=pandora-kernel.git

xen-netback: correctly return errors from netbk_count_requests()

[ Upstream commit 35876b5ffc154c357476b2c3bdab10feaf4bd8f0 ]

netbk_count_requests() could detect an error, call
netbk_fatal_tx_error() but return 0.  The vif may then be used
afterwards (e.g., in a call to netbk_tx_error().

Since netbk_fatal_tx_error() could set vif->refcnt to 1, the vif may
be freed immediately after the call to netbk_fatal_tx_error() (e.g.,
if the vif is also removed).

Netback thread              Xenwatch thread
-------------------------------------------
netbk_fatal_tx_err()        netback_remove()
                              xenvif_disconnect()
                                ...
                                free_netdev()
netbk_tx_err() Oops!

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Jan Beulich <JBeulich@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reported-by: Christopher S. Aker <caker@theshore.net>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

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