tty: audit: Handle tty audit enable atomically

The audit_tty and audit_tty_log_passwd fields are actually bool
values, so merge into single memory location to access atomically.

NB: audit log operations may still occur after tty audit is disabled
which is consistent with the existing functionality

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/audit.h b/include/linux/audit.h
index b40ed5d..e38e3fc 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -109,6 +109,10 @@
 /* maximized args number that audit_socketcall can process */
 #define AUDITSC_ARGS		6
 
+/* bit values for ->signal->audit_tty */
+#define AUDIT_TTY_ENABLE	BIT(0)
+#define AUDIT_TTY_LOG_PASSWD	BIT(1)
+
 struct filename;
 
 extern void audit_log_session_info(struct audit_buffer *ab);