remove CONFIG_UTS_NS and CONFIG_IPC_NS

CONFIG_UTS_NS and CONFIG_IPC_NS have very little value as they only
deactivate the unshare of the uts and ipc namespaces and do not improve
performance.

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

kernel/Makefile

@@ -8,7 +8,8 @@ obj-y     = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
 	    signal.o sys.o kmod.o workqueue.o pid.o \
 	    rcupdate.o extable.o params.o posix-timers.o \
 	    kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
-	    hrtimer.o rwsem.o latency.o nsproxy.o srcu.o die_notifier.o
+	    hrtimer.o rwsem.o latency.o nsproxy.o srcu.o die_notifier.o \
+	    utsname.o
 
 obj-$(CONFIG_STACKTRACE) += stacktrace.o
 obj-y += time/
@@ -48,7 +49,6 @@ obj-$(CONFIG_SECCOMP) += seccomp.o
 obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
 obj-$(CONFIG_RELAY) += relay.o
 obj-$(CONFIG_SYSCTL) += utsname_sysctl.o
-obj-$(CONFIG_UTS_NS) += utsname.o
 obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
 obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o
 

kernel/nsproxy.c

@@ -155,16 +155,6 @@ int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 	if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC)))
 		return 0;
 
-#ifndef CONFIG_IPC_NS
-	if (unshare_flags & CLONE_NEWIPC)
-		return -EINVAL;
-#endif
-
-#ifndef CONFIG_UTS_NS
-	if (unshare_flags & CLONE_NEWUTS)
-		return -EINVAL;
-#endif
-
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 

kernel/utsname_sysctl.c

@@ -18,10 +18,7 @@
 static void *get_uts(ctl_table *table, int write)
 {
 	char *which = table->data;
-#ifdef CONFIG_UTS_NS
-	struct uts_namespace *uts_ns = current->nsproxy->uts_ns;
-	which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
-#endif
+
 	if (!write)
 		down_read(&uts_sem);
 	else