+/* Compute a serial number for the audit record. Audit records are
+ * written to user-space as soon as they are generated, so a complete
+ * audit record may be written in several pieces. The timestamp of the
+ * record and this serial number are used by the user-space tools to
+ * determine which pieces belong to the same audit record. The
+ * (timestamp,serial) tuple is unique for each syscall and is live from
+ * syscall entry to syscall exit.
+ *
+ * NOTE: Another possibility is to store the formatted records off the
+ * audit context (for those records that have a context), and emit them
+ * all at syscall exit. However, this could delay the reporting of
+ * significant errors until syscall exit (or never, if the system
+ * halts). */
+
+unsigned int audit_serial(void)
+{
+ static spinlock_t serial_lock = SPIN_LOCK_UNLOCKED;
+ static unsigned int serial = 0;
+
+ unsigned long flags;
+ unsigned int ret;
+
+ spin_lock_irqsave(&serial_lock, flags);
+ do {
+ ret = ++serial;
+ } while (unlikely(!ret));
+ spin_unlock_irqrestore(&serial_lock, flags);
+
+ return ret;
+}
+
+static inline void audit_get_stamp(struct audit_context *ctx,
+ struct timespec *t, unsigned int *serial)
+{
+ if (ctx)
+ auditsc_get_stamp(ctx, t, serial);
+ else {
+ *t = CURRENT_TIME;
+ *serial = audit_serial();
+ }
+}
+