From: Roland Dreier <rolandd@cisco.com>
Date: Thu, 15 Jan 2009 05:44:39 +0000 (-0800)
Subject: IPoIB: Fix deadlock between ipoib_open() and child interface create
X-Git-Tag: v2.6.29-rc3~46^2^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cbbe1efa4972350286b52cb48aefaa11e198c0fb;p=pandora-kernel.git

IPoIB: Fix deadlock between ipoib_open() and child interface create

Fix a deadlock between child interface creation/deletion and ipoib
start/stop.  The former takes vlan_mutex, and then might take RTNL via
register_netdev()/unregister_netdev().  The latter is executed with
RTNL held, and tries to take vlan_mutex, which can lead to an AB-BA
deadlock.

Fix this by having the child interface creation/deletion code take the
RTNL first so vlan_mutex always nests inside RTNL.  We can use
register_netdevice() for child interfaces because we form the
interface name from the parent interface and hence don't need the '%'
expansion of register_netdev().

Reported-by: Yossi Etigin <yosefe@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
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