Windows supports futex-like APIs since Windows 8 and Windows Server
2012.
Signed-off-by: Akihiko Odaki <akihiko.od...@daynix.com>
---
meson.build | 2 ++
include/qemu/futex.h | 53 ++++++++++++++++++++++++++++++---------
tests/unit/test-aio-multithread.c | 2 +-
util/lockcnt.c | 2 +-
util/qemu-thread-posix.c | 4 +--
util/meson.build | 2 +-
6 files changed, 48 insertions(+), 17 deletions(-)
diff --git a/meson.build b/meson.build
index 27f115015285..11d42e4a7d39 100644
--- a/meson.build
+++ b/meson.build
@@ -835,11 +835,13 @@ emulator_link_args = []
midl = not_found
widl = not_found
pathcch = not_found
+synchronization = not_found
host_dsosuf = '.so'
if host_os == 'windows'
midl = find_program('midl', required: false)
widl = find_program('widl', required: false)
pathcch = cc.find_library('pathcch')
+ synchronization = cc.find_library('Synchronization')
socket = cc.find_library('ws2_32')
winmm = cc.find_library('winmm')
diff --git a/include/qemu/futex.h b/include/qemu/futex.h
index f57774005330..607613eec835 100644
--- a/include/qemu/futex.h
+++ b/include/qemu/futex.h
@@ -1,5 +1,5 @@
/*
- * Wrappers around Linux futex syscall
+ * Wrappers around Linux futex syscall and similar
*
* Copyright Red Hat, Inc. 2017
*
@@ -11,28 +11,37 @@
*
*/
+/*
+ * Note that a wake-up can also be caused by common futex usage patterns in
+ * unrelated code that happened to have previously used the futex word's
+ * memory location (e.g., typical futex-based implementations of Pthreads
+ * mutexes can cause this under some conditions). Therefore, qemu_futex_wait()
+ * callers should always conservatively assume that it is a spurious wake-up,
+ * and use the futex word's value (i.e., the user-space synchronization scheme)
+ * to decide whether to continue to block or not.
+ */
+
#ifndef QEMU_FUTEX_H
#define QEMU_FUTEX_H
+#define HAVE_FUTEX
+
+#ifdef CONFIG_LINUX
#include <sys/syscall.h>
#include <linux/futex.h>
#define qemu_futex(...) syscall(__NR_futex, __VA_ARGS__)
-static inline void qemu_futex_wake(void *f, int n)
+static inline void qemu_futex_wake_all(void *f)
{
- qemu_futex(f, FUTEX_WAKE, n, NULL, NULL, 0);
+ qemu_futex(f, FUTEX_WAKE, INT_MAX, NULL, NULL, 0);
+}
+
+static inline void qemu_futex_wake_single(void *f)
+{
+ qemu_futex(f, FUTEX_WAKE, 1, NULL, NULL, 0);
}
-/*
- * Note that a wake-up can also be caused by common futex usage patterns in
- * unrelated code that happened to have previously used the futex word's
- * memory location (e.g., typical futex-based implementations of Pthreads
- * mutexes can cause this under some conditions). Therefore, callers should
- * always conservatively assume that it is a spurious wake-up, and use the
futex
- * word's value (i.e., the user-space synchronization scheme) to decide whether
- * to continue to block or not.
- */
static inline void qemu_futex_wait(void *f, unsigned val)
{
while (qemu_futex(f, FUTEX_WAIT, (int) val, NULL, NULL, 0)) {
@@ -46,5 +55,25 @@ static inline void qemu_futex_wait(void *f, unsigned val)
}
}
}
+#elif defined(CONFIG_WIN32)
+#include <synchapi.h>
+
+static inline void qemu_futex_wake_all(void *f)
+{
+ WakeByAddressAll(f);
+}
+
+static inline void qemu_futex_wake_single(void *f)
+{
+ WakeByAddressSingle(f);
+}
+
+static inline void qemu_futex_wait(void *f, unsigned val)
+{
+ WaitOnAddress(f, &val, sizeof(val), INFINITE);
+}
+#else
+#undef HAVE_FUTEX
+#endif
#endif /* QEMU_FUTEX_H */
diff --git a/tests/unit/test-aio-multithread.c
b/tests/unit/test-aio-multithread.c
index 8c2e41545a29..0ead6bf34ad1 100644
--- a/tests/unit/test-aio-multithread.c
+++ b/tests/unit/test-aio-multithread.c
@@ -330,7 +330,7 @@ static void mcs_mutex_unlock(void)
/* Wake up the next in line. */
next = qatomic_read(&nodes[id].next);
nodes[next].locked = 0;
- qemu_futex_wake(&nodes[next].locked, 1);
+ qemu_futex_wake_single(&nodes[next].locked);
}
static void test_multi_fair_mutex_entry(void *opaque)
diff --git a/util/lockcnt.c b/util/lockcnt.c
index d07c6cc5cee4..ca27d8e61a5c 100644
--- a/util/lockcnt.c
+++ b/util/lockcnt.c
@@ -106,7 +106,7 @@ static bool qemu_lockcnt_cmpxchg_or_wait(QemuLockCnt
*lockcnt, int *val,
static void lockcnt_wake(QemuLockCnt *lockcnt)
{
trace_lockcnt_futex_wake(lockcnt);
- qemu_futex_wake(&lockcnt->count, 1);
+ qemu_futex_wake_single(&lockcnt->count);
}
void qemu_lockcnt_inc(QemuLockCnt *lockcnt)
diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c
index eade5311d175..13459e44c768 100644
--- a/util/qemu-thread-posix.c
+++ b/util/qemu-thread-posix.c
@@ -345,7 +345,7 @@ static inline void qemu_futex_wait(QemuEvent *ev, unsigned
val)
/* Valid transitions:
* - free->set, when setting the event
- * - busy->set, when setting the event, followed by qemu_futex_wake
+ * - busy->set, when setting the event, followed by qemu_futex_wake_all
* - set->free, when resetting the event
* - free->busy, when waiting
*
@@ -400,7 +400,7 @@ void qemu_event_set(QemuEvent *ev)
smp_mb__after_rmw();
if (old == EV_BUSY) {
/* There were waiters, wake them up. */
- qemu_futex_wake(ev, INT_MAX);
+ qemu_futex_wake_all(ev);
}
}
}
diff --git a/util/meson.build b/util/meson.build
index e5cd327e2767..c756558d6763 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -27,7 +27,7 @@ else
util_ss.add(files('event_notifier-win32.c'))
util_ss.add(files('oslib-win32.c'))
util_ss.add(files('qemu-thread-win32.c'))
- util_ss.add(winmm, pathcch)
+ util_ss.add(winmm, pathcch, synchronization)
endif
util_ss.add(when: linux_io_uring, if_true: files('fdmon-io_uring.c'))
if glib_has_gslice
--
2.49.0
