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>

12 files changed, 164 insertions, 112 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
diff --git a/init/Kconfig b/init/Kconfig
index fef641af78c2..47879a874966 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -436,6 +436,13 @@ config UTS_NS
           In this namespace tasks see different info provided with the
           uname() system call
 
+config IPC_NS
+        bool "IPC namespace"
+        depends on NAMESPACES && SYSVIPC
+        help
+          In this namespace tasks work with IPC ids which correspond to
+          different IPC objects in different namespaces
+
 config BLK_DEV_INITRD
         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
         depends on BROKEN || !FRV
diff --git a/ipc/Makefile b/ipc/Makefile
index b93bba6652f1..5fc5e33ea047 100644
--- a/ipc/Makefile
+++ b/ipc/Makefile
@@ -7,4 +7,5 @@ obj-$(CONFIG_SYSVIPC) += util.o msgutil.o msg.o sem.o shm.o
 obj-$(CONFIG_SYSVIPC_SYSCTL) += ipc_sysctl.o
 obj_mq-$(CONFIG_COMPAT) += compat_mq.o
 obj-$(CONFIG_POSIX_MQUEUE) += mqueue.o msgutil.o $(obj_mq-y)
+obj-$(CONFIG_IPC_NS) += namespace.o
 
diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
index 79e24e878c1e..7f4235bed51b 100644
--- a/ipc/ipc_sysctl.c
+++ b/ipc/ipc_sysctl.c
@@ -14,6 +14,7 @@
 #include <linux/nsproxy.h>
 #include <linux/sysctl.h>
 #include <linux/uaccess.h>
+#include <linux/ipc_namespace.h>
 
 static void *get_ipc(ctl_table *table)
 {
diff --git a/ipc/msg.c b/ipc/msg.c
index ec0c724054b9..5879bfeb79ca 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -36,6 +36,7 @@
 #include <linux/seq_file.h>
 #include <linux/rwsem.h>
 #include <linux/nsproxy.h>
+#include <linux/ipc_namespace.h>
 
 #include <asm/current.h>
 #include <asm/uaccess.h>
@@ -90,6 +91,7 @@ static void __msg_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
         ipc_init_ids(ids);
 }
 
+#ifdef CONFIG_IPC_NS
 int msg_init_ns(struct ipc_namespace *ns)
 {
         struct ipc_ids *ids;
@@ -128,6 +130,7 @@ void msg_exit_ns(struct ipc_namespace *ns)
         kfree(ns->ids[IPC_MSG_IDS]);
         ns->ids[IPC_MSG_IDS] = NULL;
 }
+#endif
 
 void __init msg_init(void)
 {
diff --git a/ipc/namespace.c b/ipc/namespace.c
new file mode 100644
index 000000000000..cef1139e6c96
--- /dev/null
+++ b/ipc/namespace.c
@@ -0,0 +1,73 @@
+/*
+ * linux/ipc/namespace.c
+ * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
+ */
+
+#include <linux/ipc.h>
+#include <linux/msg.h>
+#include <linux/ipc_namespace.h>
+#include <linux/rcupdate.h>
+#include <linux/nsproxy.h>
+#include <linux/slab.h>
+
+#include "util.h"
+
+static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
+{
+        int err;
+        struct ipc_namespace *ns;
+
+        err = -ENOMEM;
+        ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
+        if (ns == NULL)
+                goto err_mem;
+
+        err = sem_init_ns(ns);
+        if (err)
+                goto err_sem;
+        err = msg_init_ns(ns);
+        if (err)
+                goto err_msg;
+        err = shm_init_ns(ns);
+        if (err)
+                goto err_shm;
+
+        kref_init(&ns->kref);
+        return ns;
+
+err_shm:
+        msg_exit_ns(ns);
+err_msg:
+        sem_exit_ns(ns);
+err_sem:
+        kfree(ns);
+err_mem:
+        return ERR_PTR(err);
+}
+
+struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
+{
+        struct ipc_namespace *new_ns;
+
+        BUG_ON(!ns);
+        get_ipc_ns(ns);
+
+        if (!(flags & CLONE_NEWIPC))
+                return ns;
+
+        new_ns = clone_ipc_ns(ns);
+
+        put_ipc_ns(ns);
+        return new_ns;
+}
+
+void free_ipc_ns(struct kref *kref)
+{
+        struct ipc_namespace *ns;
+
+        ns = container_of(kref, struct ipc_namespace, kref);
+        sem_exit_ns(ns);
+        msg_exit_ns(ns);
+        shm_exit_ns(ns);
+        kfree(ns);
+}
diff --git a/ipc/sem.c b/ipc/sem.c
index d65e285b7e30..84c701fe5004 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -82,6 +82,7 @@
 #include <linux/seq_file.h>
 #include <linux/rwsem.h>
 #include <linux/nsproxy.h>
+#include <linux/ipc_namespace.h>
 
 #include <asm/uaccess.h>
 #include "util.h"
@@ -128,6 +129,7 @@ static void __sem_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
         ipc_init_ids(ids);
 }
 
+#ifdef CONFIG_IPC_NS
 int sem_init_ns(struct ipc_namespace *ns)
 {
         struct ipc_ids *ids;
@@ -165,6 +167,7 @@ void sem_exit_ns(struct ipc_namespace *ns)
         kfree(ns->ids[IPC_SEM_IDS]);
         ns->ids[IPC_SEM_IDS] = NULL;
 }
+#endif
 
 void __init sem_init (void)
 {
diff --git a/ipc/shm.c b/ipc/shm.c
index 65c3a294aba5..07f4b7abc80a 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -38,6 +38,7 @@
 #include <linux/rwsem.h>
 #include <linux/nsproxy.h>
 #include <linux/mount.h>
+#include <linux/ipc_namespace.h>
 
 #include <asm/uaccess.h>
 
@@ -96,6 +97,7 @@ static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
                 shm_destroy(ns, shp);
 }
 
+#ifdef CONFIG_IPC_NS
 int shm_init_ns(struct ipc_namespace *ns)
 {
         struct ipc_ids *ids;
@@ -133,6 +135,7 @@ void shm_exit_ns(struct ipc_namespace *ns)
         kfree(ns->ids[IPC_SHM_IDS]);
         ns->ids[IPC_SHM_IDS] = NULL;
 }
+#endif
 
 void __init shm_init (void)
 {
diff --git a/ipc/util.c b/ipc/util.c
index 76c1f3461e22..5432b8e34c9b 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -33,6 +33,7 @@
 #include <linux/audit.h>
 #include <linux/nsproxy.h>
 #include <linux/rwsem.h>
+#include <linux/ipc_namespace.h>
 
 #include <asm/unistd.h>
 
@@ -51,66 +52,6 @@ struct ipc_namespace init_ipc_ns = {
         },
 };
 
-static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
-{
-        int err;
-        struct ipc_namespace *ns;
-
-        err = -ENOMEM;
-        ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
-        if (ns == NULL)
-                goto err_mem;
-
-        err = sem_init_ns(ns);
-        if (err)
-                goto err_sem;
-        err = msg_init_ns(ns);
-        if (err)
-                goto err_msg;
-        err = shm_init_ns(ns);
-        if (err)
-                goto err_shm;
-
-        kref_init(&ns->kref);
-        return ns;
-
-err_shm:
-        msg_exit_ns(ns);
-err_msg:
-        sem_exit_ns(ns);
-err_sem:
-        kfree(ns);
-err_mem:
-        return ERR_PTR(err);
-}
-
-struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
-{
-        struct ipc_namespace *new_ns;
-
-        BUG_ON(!ns);
-        get_ipc_ns(ns);
-
-        if (!(flags & CLONE_NEWIPC))
-                return ns;
-
-        new_ns = clone_ipc_ns(ns);
-
-        put_ipc_ns(ns);
-        return new_ns;
-}
-
-void free_ipc_ns(struct kref *kref)
-{
-        struct ipc_namespace *ns;
-
-        ns = container_of(kref, struct ipc_namespace, kref);
-        sem_exit_ns(ns);
-        msg_exit_ns(ns);
-        shm_exit_ns(ns);
-        kfree(ns);
-}
-
 /**
  *      ipc_init        -       initialise IPC subsystem
  *
diff --git a/ipc/util.h b/ipc/util.h
index 9ffea40457ce..fc6b7294f764 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -20,6 +20,8 @@ void sem_init (void);
 void msg_init (void);
 void shm_init (void);
 
+struct ipc_namespace;
+
 int sem_init_ns(struct ipc_namespace *ns);
 int msg_init_ns(struct ipc_namespace *ns);
 int shm_init_ns(struct ipc_namespace *ns);
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index 79f871bc0ef4..f5d332cf8c63 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -21,6 +21,7 @@
 #include <linux/utsname.h>
 #include <linux/pid_namespace.h>
 #include <net/net_namespace.h>
+#include <linux/ipc_namespace.h>
 
 static struct kmem_cache *nsproxy_cachep;