From 40842ae998ba587a0514327e805fc7936db76b3b Mon Sep 17 00:00:00 2001
From: Guillaume Quintard <guillaume.quintard@gmail.com>
Date: Wed, 30 Mar 2022 19:45:37 -0700
Subject: [PATCH] align vmb.h with the varnish version

---
 configure.ac |  2 ++
 src/vmb.h    | 52 ++++++++++++++++------------------------------------
 2 files changed, 18 insertions(+), 36 deletions(-)

diff --git a/configure.ac b/configure.ac
index a78fdbf..9b54203 100644
--- a/configure.ac
+++ b/configure.ac
@@ -13,6 +13,8 @@ AM_PROG_AR
 LT_PREREQ([2.2.6])
 LT_INIT([dlopen disable-static])
 
+AC_CHECK_HEADERS([stdatomic.h])
+
 AC_ARG_WITH([rst2man],
 	AS_HELP_STRING(
 		[--with-rst2man=PATH],
diff --git a/src/vmb.h b/src/vmb.h
index 9c148fb..2e3f525 100644
--- a/src/vmb.h
+++ b/src/vmb.h
@@ -4,6 +4,8 @@
  *
  * Author: Poul-Henning Kamp <phk@phk.freebsd.dk>
  *
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
@@ -27,60 +29,38 @@
  *
  * Memory barriers
  *
- * XXX: It is utterly braindamaged, that no standard facility for this
- * XXX: is available.  The "just use pthreads locking" excuse does not
- * XXX: make sense, and does not apply to two unthreaded programs sharing
- * XXX: a memory segment.
  */
 
 #ifndef VMB_H_INCLUDED
 #define VMB_H_INCLUDED
 
-#if defined(__FreeBSD__)
-#include <sys/param.h>
-#endif
-
-#if defined(__FreeBSD__) && __FreeBSD_version >= 800058
+#if defined(HAVE_STDATOMIC_H) && !defined(__FLEXELINT__)
 
-#include <sys/types.h>
-#include <machine/atomic.h>
-#define VMB()	mb()
-#define VWMB()	wmb()
-#define VRMB()	rmb()
+#  include <stdatomic.h>
+#  define VWMB()	atomic_thread_fence(memory_order_release)
+#  define VRMB()	atomic_thread_fence(memory_order_acquire)
 
 #elif defined(__amd64__) && defined(__GNUC__)
 
-#define VMB()	__asm __volatile("mfence;" : : : "memory")
-#define VWMB()	__asm __volatile("sfence;" : : : "memory")
-#define VRMB()	__asm __volatile("lfence;" : : : "memory")
-
-#elif defined(__arm__)
-
-#define VMB()
-#define VWMB()
-#define VRMB()
+#  define VWMB()	__asm __volatile("sfence;" : : : "memory")
+#  define VRMB()	__asm __volatile("lfence;" : : : "memory")
 
 #elif defined(__i386__) && defined(__GNUC__)
 
-#define VMB()	__asm __volatile("lock; addl $0,(%%esp)" : : : "memory")
-#define VWMB()	__asm __volatile("lock; addl $0,(%%esp)" : : : "memory")
-#define VRMB()	__asm __volatile("lock; addl $0,(%%esp)" : : : "memory")
+#  define VWMB()	__asm __volatile("lock; addl $0,(%%esp)" : : : "memory")
+#  define VRMB()	__asm __volatile("lock; addl $0,(%%esp)" : : : "memory")
 
 #elif defined(__sparc64__) && defined(__GNUC__)
 
-#define VMB()	__asm__ __volatile__ ("membar #MemIssue": : :"memory")
-#define VWMB()	VMB()
-#define VRMB()	VMB()
+#  define VWMB()	__asm__ __volatile__ ("membar #MemIssue": : :"memory")
+#  define VRMB()	__asm__ __volatile__ ("membar #MemIssue": : :"memory")
 
 #else
 
-#define VMB_NEEDS_PTHREAD_WORKAROUND_THIS_IS_BAD_FOR_PERFORMANCE 1
-
-void vmb_pthread(void);
-
-#define VMB()	vmb_pthread()
-#define VWMB()	vmb_pthread()
-#define VRMB()	vmb_pthread()
+#  define VMB_NEEDS_PTHREAD_WORKAROUND_THIS_IS_BAD_FOR_PERFORMANCE 1
+   void vmb_pthread(void);
+#  define VWMB()	vmb_pthread()
+#  define VRMB()	vmb_pthread()
 
 #endif