From 2030a00e9d90477544aec48220d865979b8ab57c Mon Sep 17 00:00:00 2001
From: Tomas Jedlicka <tomas.jedlicka@oracle.com>
Date: Thu, 30 Mar 2017 09:22:47 -0400
Subject: [PATCH] dtrace: DTrace walltime lock-free implementation

DTrace walltimestamp is now based on reading current kernel
timespec without taking locks.

Orabug: 25715256

Signed-off-by: Tomas Jedlicka <tomas.jedlicka@oracle.com>
Reviewed-by: Kris Van Hees <kris.van.hees@oracle.com>
Acked-by: Nick Alcock <nick.alcock@oracle.com>
---
 include/linux/dtrace_os.h |  4 +++-
 kernel/dtrace/dtrace_os.c | 11 ++++++++++-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/include/linux/dtrace_os.h b/include/linux/dtrace_os.h
index 90952301a013..e3200c2d6c84 100644
--- a/include/linux/dtrace_os.h
+++ b/include/linux/dtrace_os.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2011-2014 Oracle, Inc. */
+/* Copyright (c) 2011, 2017, Oracle and/or its affiliates. All rights reserved. */
 
 #ifndef _LINUX_DTRACE_OS_H_
 #define _LINUX_DTRACE_OS_H_
@@ -36,6 +36,8 @@ typedef enum dtrace_vtime_state {
 
 extern dtrace_vtime_state_t dtrace_vtime_active;
 
+extern ktime_t dtrace_get_walltime(void);
+
 extern void dtrace_vtime_enable(void);
 extern void dtrace_vtime_disable(void);
 extern void dtrace_vtime_switch(struct task_struct *, struct task_struct *);
diff --git a/kernel/dtrace/dtrace_os.c b/kernel/dtrace/dtrace_os.c
index 2a6941772fba..72d0746748c6 100644
--- a/kernel/dtrace/dtrace_os.c
+++ b/kernel/dtrace/dtrace_os.c
@@ -2,7 +2,7 @@
  * FILE:	dtrace_os.c
  * DESCRIPTION:	Dynamic Tracing: OS support functions - part of kernel core
  *
- * Copyright (C) 2010-2014 Oracle Corporation
+ * Copyright (c) 2010, 2017, Oracle and/or its affiliates. All rights reserved.
  */
 
 #include <linux/binfmts.h>
@@ -19,6 +19,7 @@
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/stacktrace.h>
+#include <linux/timekeeping.h>
 #include <linux/vmalloc.h>
 #include <linux/kallsyms.h>
 #include <linux/workqueue.h>
@@ -335,6 +336,14 @@ void dtrace_psinfo_free(struct task_struct *tsk)
 \*---------------------------------------------------------------------------*/
 dtrace_vtime_state_t	dtrace_vtime_active = 0;
 
+ktime_t dtrace_get_walltime(void)
+{
+	struct timespec t = __current_kernel_time();
+
+	return ns_to_ktime(timespec64_to_ns(&t));
+}
+EXPORT_SYMBOL(dtrace_get_walltime);
+
 void dtrace_vtime_enable(void)
 {
 	dtrace_vtime_state_t	old, new;
-- 
2.50.1