From: Akihiko Odaki <akihiko.odaki@daynix.com>
Date: Thu, 29 May 2025 05:45:55 +0000 (+0900)
Subject: qemu-thread: Use futex if available for QemuLockCnt
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0a765ca850125e0202c366cb4aab032ac9670870;p=thirdparty%2Fqemu.git

qemu-thread: Use futex if available for QemuLockCnt

This unlocks the futex-based implementation of QemuLockCnt to Windows.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Link: https://lore.kernel.org/r/20250529-event-v5-6-53b285203794@daynix.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/include/qemu/lockcnt.h b/include/qemu/lockcnt.h
index f4b62a3f70..5a2800e3f1 100644
--- a/include/qemu/lockcnt.h
+++ b/include/qemu/lockcnt.h
@@ -17,7 +17,7 @@
 typedef struct QemuLockCnt QemuLockCnt;
 
 struct QemuLockCnt {
-#ifndef CONFIG_LINUX
+#ifndef HAVE_FUTEX
     QemuMutex mutex;
 #endif
     unsigned count;
diff --git a/util/lockcnt.c b/util/lockcnt.c
index ca27d8e61a..92c9f8ceca 100644
--- a/util/lockcnt.c
+++ b/util/lockcnt.c
@@ -12,10 +12,11 @@
 #include "qemu/atomic.h"
 #include "trace.h"
 
-#ifdef CONFIG_LINUX
-#include "qemu/futex.h"
+#ifdef HAVE_FUTEX
 
-/* On Linux, bits 0-1 are a futex-based lock, bits 2-31 are the counter.
+/*
+ * When futex is available, bits 0-1 are a futex-based lock, bits 2-31 are the
+ * counter.
  * For the mutex algorithm see Ulrich Drepper's "Futexes Are Tricky" (ok,
  * this is not the most relaxing citation I could make...).  It is similar
  * to mutex2 in the paper.