[PATCH] IPC namespace core

This patch set allows to unshare IPCs and have a private set of IPC objects
(sem, shm, msg) inside namespace.  Basically, it is another building block of
containers functionality.

This patch implements core IPC namespace changes:
- ipc_namespace structure
- new config option CONFIG_IPC_NS
- adds CLONE_NEWIPC flag
- unshare support

[clg@fr.ibm.com: small fix for unshare of ipc namespace]
[akpm@osdl.org: build fix]
Signed-off-by: Pavel Emelianov <xemul@openvz.org>
Signed-off-by: Kirill Korotaev <dev@openvz.org>
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

init/Kconfig

@@ -115,6 +115,15 @@ config SYSVIPC
 	  section 6.4 of the Linux Programmer's Guide, available from
 	  <http://www.tldp.org/guides.html>.
 
+config IPC_NS
+	bool "IPC Namespaces"
+	depends on SYSVIPC
+	default n
+	help
+	  Support ipc namespaces.  This allows containers, i.e. virtual
+	  environments, to use ipc namespaces to provide different ipc
+	  objects for different servers.  If unsure, say N.
+
 config POSIX_MQUEUE
 	bool "POSIX Message Queues"
 	depends on NET && EXPERIMENTAL