ipc: delete "nr_ipc_ns"

Write-only variable.

Link: http://lkml.kernel.org/r/20160708214356.GA6785@p183.telecom.by
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/ipc_namespace.h

@@ -63,8 +63,6 @@ struct ipc_namespace {
 };
 
 extern struct ipc_namespace init_ipc_ns;
-extern atomic_t nr_ipc_ns;
-
 extern spinlock_t mq_lock;
 
 #ifdef CONFIG_SYSVIPC

ipc/msgutil.c

@@ -37,8 +37,6 @@ struct ipc_namespace init_ipc_ns = {
 #endif
 };
 
-atomic_t nr_ipc_ns = ATOMIC_INIT(1);
-
 struct msg_msgseg {
 	struct msg_msgseg *next;
 	/* the next part of the message follows immediately */

ipc/namespace.c

@@ -43,7 +43,6 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
 		kfree(ns);
 		return ERR_PTR(err);
 	}
-	atomic_inc(&nr_ipc_ns);
 
 	sem_init_ns(ns);
 	msg_init_ns(ns);
@@ -96,7 +95,6 @@ static void free_ipc_ns(struct ipc_namespace *ns)
 	sem_exit_ns(ns);
 	msg_exit_ns(ns);
 	shm_exit_ns(ns);
-	atomic_dec(&nr_ipc_ns);
 
 	put_user_ns(ns->user_ns);
 	ns_free_inum(&ns->ns);