sethostname/setdomainname: notify userspace when there is a change in uts_kern_table

sethostname() and setdomainname() notify userspace on failure (without
modifying uts_kern_table).  Change things so that we only notify userspace
on success, when uts_kern_table was actually modified.
Signed-off-by: NSasikantha babu <sasikanth.v19@gmail.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: WANG Cong <amwang@redhat.com>
Reviewed-by: NCyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kernel/sys.c

@@ -1378,8 +1378,8 @@ SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
 		memcpy(u->nodename, tmp, len);
 		memset(u->nodename + len, 0, sizeof(u->nodename) - len);
 		errno = 0;
+		uts_proc_notify(UTS_PROC_HOSTNAME);
 	}
-	uts_proc_notify(UTS_PROC_HOSTNAME);
 	up_write(&uts_sem);
 	return errno;
 }
@@ -1429,8 +1429,8 @@ SYSCALL_DEFINE2(setdomainname, char __user *, name, int, len)
 		memcpy(u->domainname, tmp, len);
 		memset(u->domainname + len, 0, sizeof(u->domainname) - len);
 		errno = 0;
+		uts_proc_notify(UTS_PROC_DOMAINNAME);
 	}
-	uts_proc_notify(UTS_PROC_DOMAINNAME);
 	up_write(&uts_sem);
 	return errno;
 }