From 81747ac6d3e846d1955edaa94dee9065e541b7d8 Mon Sep 17 00:00:00 2001
From: Justus Winter <4winter@informatik.uni-hamburg.de>
Date: Mon, 7 Sep 2015 13:04:39 +0200
Subject: kern: use proper memory fences when handling the mapped time

* include/mach/time_value.h (struct mapped_time_value): Adjust comment.
* kern/mach_clock.c (mtime): Likewise.  Also make it volatile.
(update_mapped_time): Use full hardware barriers.
(read_mapped_time): New macro with proper fences.
(record_time_stamp, host_get_time): Use the new macro.
---
 include/mach/time_value.h | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'include/mach')

diff --git a/include/mach/time_value.h b/include/mach/time_value.h
index 61be581..0dfe382 100644
--- a/include/mach/time_value.h
+++ b/include/mach/time_value.h
@@ -84,7 +84,9 @@ typedef	struct time_value	time_value_t;
  *	Read this mapped value with
  *		do {
  *			secs = mtime->seconds;
+ *			__sync_synchronize();
  *			usecs = mtime->microseconds;
+ *			__sync_synchronize();
  *		} while (secs != mtime->check_seconds);
  */
 
-- 
cgit v1.2.3