Attachment 65504 Details for Bug 41423 – [alternative] Use InterlockedExchange to get a full memory barrier on Windows

[patch] [alternative] Use InterlockedExchange to get a full memory barrier on Windows

0001-Use-InterlockedExchange-to-get-a-full-memory-barrier.patch (text/plain), 1.28 KB, created by Simon McVittie on 2012-08-13 17:07:15 UTC

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Creator: Simon McVittie

Created: 2012-08-13 17:07:15 UTC

Size: 1.28 KB

patch

obsolete

>From fbebc15ebcdfb94d7135b327ad7ee27a919db4e1 Mon Sep 17 00:00:00 2001
>From: Simon McVittie <simon.mcvittie@collabora.co.uk>
>Date: Mon, 13 Aug 2012 18:00:23 +0100
>Subject: [PATCH] Use InterlockedExchange to get a full memory barrier on
> Windows
>
>See the bug for extensive discussion.
>
>Bug: https://bugs.freedesktop.org/show_bug.cgi?id=41423
>---
> dbus/dbus-sysdeps-win.c |   14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
>diff --git a/dbus/dbus-sysdeps-win.c b/dbus/dbus-sysdeps-win.c
>index 397520a..488077d 100644
>--- a/dbus/dbus-sysdeps-win.c
>+++ b/dbus/dbus-sysdeps-win.c
>@@ -3121,8 +3121,18 @@ _dbus_atomic_dec (DBusAtomic *atomic)
> dbus_int32_t
> _dbus_atomic_get (DBusAtomic *atomic)
> {
>-  /* this is what GLib does, hopefully it's right... */
>-  MemoryBarrier ();
>+  /* In this situation, GLib issues a MemoryBarrier() and then returns
>+   * atomic->value. However, mingw from mingw.org (not to be confused with
>+   * mingw-w64 from mingw-w64.sf.net) does not have MemoryBarrier in its
>+   * headers, so we have to get a memory barrier some other way.
>+   *
>+   * InterlockedIncrement is older, and is documented on MSDN to be a full
>+   * memory barrier, so let's use that.
>+   */
>+  long dummy = 0;
>+
>+  InterlockedExchange (&dummy, 1);
>+
>   return atomic->value;
> }
> 
>-- 
>1.7.10.4
>

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Attachments on bug 41423: 65342 | 65504

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