namespaces: move the IPC namespace under IPC_NS option

Currently the IPC namespace management code is spread over the ipc/*.c files.
I moved this code into ipc/namespace.c file which is compiled out when needed.

The linux/ipc_namespace.h file is used to store the prototypes of the
functions in namespace.c and the stubs for NAMESPACES=n case.  This is done
so, because the stub for copy_ipc_namespace requires the knowledge of the
CLONE_NEWIPC flag, which is in sched.h.  But the linux/ipc.h file itself in
included into many many .c files via the sys.h->sem.h sequence so adding the
sched.h into it will make all these .c depend on sched.h which is not that
good.  On the other hand the knowledge about the namespaces stuff is required
in 4 .c files only.

Besides, this patch compiles out some auxiliary functions from ipc/sem.c,
msg.c and shm.c files.  It turned out that moving these functions into
namespaces.c is not that easy because they use many other calls and macros
from the original file.  Moving them would make this patch complicated.  On
the other hand all these functions can be consolidated, so I will send a
separate patch doing this a bit later.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 69 insertions, 52 deletions

diff --git a/include/linux/ipc.h b/include/linux/ipc.h
index 408696ea5189..b8826107b518 100644
--- a/include/linux/ipc.h
+++ b/include/linux/ipc.h
@@ -100,58 +100,6 @@ struct kern_ipc_perm
         void            *security;
 };
 
-struct ipc_ids;
-struct ipc_namespace {
-        struct kref     kref;
-        struct ipc_ids  *ids[3];
-
-        int             sem_ctls[4];
-        int             used_sems;
-
-        int             msg_ctlmax;
-        int             msg_ctlmnb;
-        int             msg_ctlmni;
-        atomic_t        msg_bytes;
-        atomic_t        msg_hdrs;
-
-        size_t          shm_ctlmax;
-        size_t          shm_ctlall;
-        int             shm_ctlmni;
-        int             shm_tot;
-};
-
-extern struct ipc_namespace init_ipc_ns;
-
-#ifdef CONFIG_SYSVIPC
-#define INIT_IPC_NS(ns)         .ns             = &init_ipc_ns,
-extern void free_ipc_ns(struct kref *kref);
-extern struct ipc_namespace *copy_ipcs(unsigned long flags,
-                                                struct ipc_namespace *ns);
-#else
-#define INIT_IPC_NS(ns)
-static inline struct ipc_namespace *copy_ipcs(unsigned long flags,
-                                                struct ipc_namespace *ns)
-{
-        return ns;
-}
-#endif
-
-static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
-{
-#ifdef CONFIG_SYSVIPC
-        if (ns)
-                kref_get(&ns->kref);
-#endif
-        return ns;
-}
-
-static inline void put_ipc_ns(struct ipc_namespace *ns)
-{
-#ifdef CONFIG_SYSVIPC
-        kref_put(&ns->kref, free_ipc_ns);
-#endif
-}
-
 #endif /* __KERNEL__ */
 
 #endif /* _LINUX_IPC_H */
diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
new file mode 100644
index 000000000000..a491fc9dd231
--- /dev/null
+++ b/include/linux/ipc_namespace.h
@@ -0,0 +1,69 @@
+#ifndef __IPC_NAMESPACE_H__
+#define __IPC_NAMESPACE_H__
+
+#include <linux/err.h>
+
+struct ipc_ids;
+struct ipc_namespace {
+        struct kref     kref;
+        struct ipc_ids  *ids[3];
+
+        int             sem_ctls[4];
+        int             used_sems;
+
+        int             msg_ctlmax;
+        int             msg_ctlmnb;
+        int             msg_ctlmni;
+        atomic_t        msg_bytes;
+        atomic_t        msg_hdrs;
+
+        size_t          shm_ctlmax;
+        size_t          shm_ctlall;
+        int             shm_ctlmni;
+        int             shm_tot;
+};
+
+extern struct ipc_namespace init_ipc_ns;
+
+#ifdef CONFIG_SYSVIPC
+#define INIT_IPC_NS(ns)         .ns             = &init_ipc_ns,
+#else
+#define INIT_IPC_NS(ns)
+#endif
+
+#if defined(CONFIG_SYSVIPC) && defined(CONFIG_IPC_NS)
+extern void free_ipc_ns(struct kref *kref);
+extern struct ipc_namespace *copy_ipcs(unsigned long flags,
+                                                struct ipc_namespace *ns);
+
+static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
+{
+        if (ns)
+                kref_get(&ns->kref);
+        return ns;
+}
+
+static inline void put_ipc_ns(struct ipc_namespace *ns)
+{
+        kref_put(&ns->kref, free_ipc_ns);
+}
+#else
+static inline struct ipc_namespace *copy_ipcs(unsigned long flags,
+                struct ipc_namespace *ns)
+{
+        if (flags & CLONE_NEWIPC)
+                return ERR_PTR(-EINVAL);
+
+        return ns;
+}
+
+static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
+{
+        return ns;
+}
+
+static inline void put_ipc_ns(struct ipc_namespace *ns)
+{
+}
+#endif
+#endif