[PATCH V2] backport: add backport for get_net_ns_by_fd()

[Arend van Spriel <arend@broadcom.com>]

In mac80211-next a call to get_net_ns_by_fd() has been added in cfg80211
which resides in networking core. This function has been backported
such that it will always fail, ie. as it would when CONFIG_NET_NS
is not defined. The call was added by:

   commit 4b681c82d2f9bef121c912ffcaac89a004af3f2c
   Author: Vadim Kochan <vadim4j@gmail.com>
   Date: Mon Jan 12 16:34:05 2015 +0200

     nl80211: Allow set network namespace by fd

Signed-off-by: Arend van Spriel <arend@broadcom.com>
---
This patch replaces the commit
"backport: add backport file for the next kernel release" which
has Message-ID: <1422648758-31361-2-git-send-email-arend@broadcom.com>

Changes:
 V2
  - solve backport using LINUX_BACKPORT macro (Johannes Berg)
---
 backport/backport-include/net/net_namespace.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/backport/backport-include/net/net_namespace.h b/backport/backport-include/net/net_namespace.h
index e83b103..8927af7 100644
--- a/backport/backport-include/net/net_namespace.h
+++ b/backport/backport-include/net/net_namespace.h
@@ -24,4 +24,10 @@ net_ieee802154_lowpan(struct net *net)
 #endif /* LINUX_VERSION_CODE < KERNEL_VERSION(3,15,0) */
 #endif /* CPTCFG_IEEE802154_6LOWPAN */
 
+#define get_net_ns_by_fd	LINUX_BACKPORT(get_net_ns_by_fd)
+static inline struct net *get_net_ns_by_fd(int fd)
+{
+	return ERR_PTR(-EINVAL);
+}
+
 #endif	/* _COMPAT_NET_NET_NAMESPACE_H */
-- 
1.9.1