ipc: simplify rcu_read_lock() in semctl_nolock()

This trivially combines two rcu_read_lock() calls in both sides of a
if-statement into one single one in front of the if-statement.

Split out as an independent cleanup from the previous commit.
Acked-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ipc/sem.c

@@ -948,8 +948,8 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid,
 
 		memset(&tbuf, 0, sizeof(tbuf));
 
-		if (cmd == SEM_STAT) {
 		rcu_read_lock();
+		if (cmd == SEM_STAT) {
 			sma = sem_obtain_object(ns, semid);
 			if (IS_ERR(sma)) {
 				err = PTR_ERR(sma);
@@ -957,7 +957,6 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid,
 			}
 			id = sma->sem_perm.id;
 		} else {
-			rcu_read_lock();
 			sma = sem_obtain_object_check(ns, semid);
 			if (IS_ERR(sma)) {
 				err = PTR_ERR(sma);