v4.19.13 snapshot.
diff --git a/include/linux/latencytop.h b/include/linux/latencytop.h
new file mode 100644
index 0000000..7c560e0
--- /dev/null
+++ b/include/linux/latencytop.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * latencytop.h: Infrastructure for displaying latency
+ *
+ * (C) Copyright 2008 Intel Corporation
+ * Author: Arjan van de Ven <arjan@linux.intel.com>
+ *
+ */
+
+#ifndef _INCLUDE_GUARD_LATENCYTOP_H_
+#define _INCLUDE_GUARD_LATENCYTOP_H_
+
+#include <linux/compiler.h>
+struct task_struct;
+
+#ifdef CONFIG_LATENCYTOP
+
+#define LT_SAVECOUNT 32
+#define LT_BACKTRACEDEPTH 12
+
+struct latency_record {
+ unsigned long backtrace[LT_BACKTRACEDEPTH];
+ unsigned int count;
+ unsigned long time;
+ unsigned long max;
+};
+
+
+
+extern int latencytop_enabled;
+void __account_scheduler_latency(struct task_struct *task, int usecs, int inter);
+static inline void
+account_scheduler_latency(struct task_struct *task, int usecs, int inter)
+{
+ if (unlikely(latencytop_enabled))
+ __account_scheduler_latency(task, usecs, inter);
+}
+
+void clear_all_latency_tracing(struct task_struct *p);
+
+extern int sysctl_latencytop(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos);
+
+#else
+
+static inline void
+account_scheduler_latency(struct task_struct *task, int usecs, int inter)
+{
+}
+
+static inline void clear_all_latency_tracing(struct task_struct *p)
+{
+}
+
+#endif
+
+#endif