From: Eric W. Biederman <ebiederm@aristanetworks.com>
Date: Mon, 8 Jun 2009 07:44:31 +0000 (-0700)
Subject: tun: Fix unregister race
X-Git-Tag: v2.6.31-rc1~330^2~114
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f0a4d0e5b5bfd271e6737f7c095994835b70d450;p=pandora-kernel.git

tun: Fix unregister race

It is possible for tun_chr_close to race with dellink on the
a tun device.  In which case if __tun_get runs before dellink
but dellink runs before tun_chr_close calls unregister_netdevice
we will attempt to unregister the netdevice after it is already
gone.

The two cases are already serialized on the rtnl_lock, so I have
gone for the cheap simple fix of moving rtnl_lock to cover __tun_get
in tun_chr_close.  Eliminating the possibility of the tun device
being unregistered between __tun_get and unregister_netdevice in
tun_chr_close.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Tested-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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