[PATCH -mm] uts namespace : remove CONFIG_UTS_NS

[Serge E. Hallyn]

Quoting Cedric Le Goater (clg at fr.ibm.com):
> CONFIG_UTS_NS has very little value as it only deactivates the unshare
> of the uts namespace and does not improve performance.
> 
> Signed-off-by: Cedric Le Goater <clg at fr.ibm.com>

It really is worthless complication, with the sole effect being to
complicate testing...

Acked-by: Serge Hallyn <serue at us.ibm.com>

> ---
>  include/linux/utsname.h |   19 -------------------
>  init/Kconfig            |    8 --------
>  kernel/Makefile         |    3 +--
>  kernel/sysctl.c         |    3 +--
>  4 files changed, 2 insertions(+), 31 deletions(-)
> 
> Index: 2.6.20-rc4-mm1/include/linux/utsname.h
> ===================================================================
> --- 2.6.20-rc4-mm1.orig/include/linux/utsname.h
> +++ 2.6.20-rc4-mm1/include/linux/utsname.h
> @@ -48,7 +48,6 @@ static inline void get_uts_ns(struct uts
>  	kref_get(&ns->kref);
>  }
> 
> -#ifdef CONFIG_UTS_NS
>  extern int unshare_utsname(unsigned long unshare_flags,
>  				struct uts_namespace **new_uts);
>  extern int copy_utsname(int flags, struct task_struct *tsk);
> @@ -58,24 +57,6 @@ static inline void put_uts_ns(struct uts
>  {
>  	kref_put(&ns->kref, free_uts_ns);
>  }
> -#else
> -static inline int unshare_utsname(unsigned long unshare_flags,
> -			struct uts_namespace **new_uts)
> -{
> -	if (unshare_flags & CLONE_NEWUTS)
> -		return -EINVAL;
> -
> -	return 0;
> -}
> -
> -static inline int copy_utsname(int flags, struct task_struct *tsk)
> -{
> -	return 0;
> -}
> -static inline void put_uts_ns(struct uts_namespace *ns)
> -{
> -}
> -#endif
> 
>  static inline struct new_utsname *utsname(void)
>  {
> Index: 2.6.20-rc4-mm1/init/Kconfig
> ===================================================================
> --- 2.6.20-rc4-mm1.orig/init/Kconfig
> +++ 2.6.20-rc4-mm1/init/Kconfig
> @@ -205,14 +205,6 @@ config TASK_DELAY_ACCT
> 
>  	  Say N if unsure.
> 
> -config UTS_NS
> -	bool "UTS Namespaces"
> -	default n
> -	help
> -	  Support uts namespaces.  This allows containers, i.e.
> -	  vservers, to use uts namespaces to provide different
> -	  uts info for different servers.  If unsure, say N.
> -
>  config AUDIT
>  	bool "Auditing support"
>  	depends on NET
> Index: 2.6.20-rc4-mm1/kernel/Makefile
> ===================================================================
> --- 2.6.20-rc4-mm1.orig/kernel/Makefile
> +++ 2.6.20-rc4-mm1/kernel/Makefile
> @@ -8,7 +8,7 @@ obj-y     = sched.o fork.o exec_domain.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
> +	    hrtimer.o rwsem.o latency.o nsproxy.o srcu.o utsname.o
> 
>  obj-$(CONFIG_STACKTRACE) += stacktrace.o
>  obj-y += time/
> @@ -48,7 +48,6 @@ obj-$(CONFIG_SECCOMP) += seccomp.o
>  obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
>  obj-$(CONFIG_DEBUG_SYNCHRO_TEST) += synchro-test.o
>  obj-$(CONFIG_RELAY) += relay.o
> -obj-$(CONFIG_UTS_NS) += utsname.o
>  obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
>  obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o
> 
> Index: 2.6.20-rc4-mm1/kernel/sysctl.c
> ===================================================================
> --- 2.6.20-rc4-mm1.orig/kernel/sysctl.c
> +++ 2.6.20-rc4-mm1/kernel/sysctl.c
> @@ -187,10 +187,9 @@ int sysctl_legacy_va_layout;
>  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