5.6.35-80.0

1 files changed, 32 insertions, 12 deletions

diff --git a/storage/xtradb/mach/mach0data.cc b/storage/xtradb/mach/mach0data.cc
index 206434dc5ab..feeedb01609 100644
--- a/storage/xtradb/mach/mach0data.cc
+++ b/storage/xtradb/mach/mach0data.cc
@@ -1,6 +1,6 @@
 /*****************************************************************************
 
-Copyright (c) 1995, 2009, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 1995, 2016, Oracle and/or its affiliates. All Rights Reserved.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -55,7 +55,6 @@ mach_parse_compressed(
 	if (flag < 0x80UL) {
 		*val = flag;
 		return(ptr + 1);
-
 	}
 
 	/* Workaround GCC bug
@@ -64,7 +63,11 @@ mach_parse_compressed(
 	function, causing and out-of-bounds read if we are reading a short
 	integer close to the end of buffer. */
 #if defined(__GNUC__) && (__GNUC__ >= 5) && !defined(__clang__)
-	asm volatile("": : :"memory");
+#define DEPLOY_FENCE
+#endif
+
+#ifdef DEPLOY_FENCE
+	__atomic_thread_fence(__ATOMIC_ACQUIRE);
 #endif
 
 	if (flag < 0xC0UL) {
@@ -75,8 +78,13 @@ mach_parse_compressed(
 		*val = mach_read_from_2(ptr) & 0x7FFFUL;
 
 		return(ptr + 2);
+	}
 
-	} else if (flag < 0xE0UL) {
+#ifdef DEPLOY_FENCE
+	__atomic_thread_fence(__ATOMIC_ACQUIRE);
+#endif
+
+	if (flag < 0xE0UL) {
 		if (end_ptr < ptr + 3) {
 			return(NULL);
 		}
@@ -84,7 +92,13 @@ mach_parse_compressed(
 		*val = mach_read_from_3(ptr) & 0x3FFFFFUL;
 
 		return(ptr + 3);
-	} else if (flag < 0xF0UL) {
+	}
+
+#ifdef DEPLOY_FENCE
+	__atomic_thread_fence(__ATOMIC_ACQUIRE);
+#endif
+
+	if (flag < 0xF0UL) {
 		if (end_ptr < ptr + 4) {
 			return(NULL);
 		}
@@ -92,14 +106,20 @@ mach_parse_compressed(
 		*val = mach_read_from_4(ptr) & 0x1FFFFFFFUL;
 
 		return(ptr + 4);
-	} else {
-		ut_ad(flag == 0xF0UL);
+	}
 
-		if (end_ptr < ptr + 5) {
-			return(NULL);
-		}
+#ifdef DEPLOY_FENCE
+	__atomic_thread_fence(__ATOMIC_ACQUIRE);
+#endif
 
-		*val = mach_read_from_4(ptr + 1);
-		return(ptr + 5);
+#undef DEPLOY_FENCE
+
+	ut_ad(flag == 0xF0UL);
+
+	if (end_ptr < ptr + 5) {
+		return(NULL);
 	}
+
+	*val = mach_read_from_4(ptr + 1);
+	return(ptr + 5);
 }