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[Qemu-devel] [UPDATED v3 05/11] qemu-thread: add simple test-and-set spi
From: |
Emilio G. Cota |
Subject: |
[Qemu-devel] [UPDATED v3 05/11] qemu-thread: add simple test-and-set spinlock |
Date: |
Wed, 20 Apr 2016 13:35:55 -0400 |
From: Guillaume Delbergue <address@hidden>
Signed-off-by: Guillaume Delbergue <address@hidden>
[Rewritten. - Paolo]
Signed-off-by: Paolo Bonzini <address@hidden>
[Emilio's additions: call cpu_relax() while spinning; optimize for
uncontended locks by acquiring the lock with test-and-set instead of
test-and-test-and-set.]
Signed-off-by: Emilio G. Cota <address@hidden>
---
include/qemu/thread.h | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/include/qemu/thread.h b/include/qemu/thread.h
index bdae6df..a216941 100644
--- a/include/qemu/thread.h
+++ b/include/qemu/thread.h
@@ -1,6 +1,9 @@
#ifndef __QEMU_THREAD_H
#define __QEMU_THREAD_H 1
+#include <errno.h>
+#include "qemu/processor.h"
+#include "qemu/atomic.h"
typedef struct QemuMutex QemuMutex;
typedef struct QemuCond QemuCond;
@@ -60,4 +63,35 @@ struct Notifier;
void qemu_thread_atexit_add(struct Notifier *notifier);
void qemu_thread_atexit_remove(struct Notifier *notifier);
+typedef struct QemuSpin {
+ int value;
+} QemuSpin;
+
+static inline void qemu_spin_init(QemuSpin *spin)
+{
+ spin->value = 0;
+}
+
+static inline void qemu_spin_lock(QemuSpin *spin)
+{
+ while (atomic_xchg(&spin->value, true)) {
+ while (atomic_read(&spin->value)) {
+ cpu_relax();
+ }
+ }
+}
+
+static inline int qemu_spin_trylock(QemuSpin *spin)
+{
+ if (atomic_xchg(&spin->value, true)) {
+ return -EBUSY;
+ }
+ return 0;
+}
+
+static inline void qemu_spin_unlock(QemuSpin *spin)
+{
+ atomic_mb_set(&spin->value, 0);
+}
+
#endif
--
2.5.0
- Re: [Qemu-devel] [PATCH v3 01/11] compiler.h: add QEMU_ALIGNED() to enforce struct alignment, (continued)
- [Qemu-devel] [PATCH v3 05/11] qemu-thread: add simple test-and-set spinlock, Emilio G. Cota, 2016/04/19
- Re: [Qemu-devel] [PATCH v3 05/11] qemu-thread: add simple test-and-set spinlock, Richard Henderson, 2016/04/20
- Re: [Qemu-devel] [PATCH v3 05/11] qemu-thread: add simple test-and-set spinlock, Emilio G. Cota, 2016/04/20
- Re: [Qemu-devel] [PATCH v3 05/11] qemu-thread: add simple test-and-set spinlock, Richard Henderson, 2016/04/20
- Re: [Qemu-devel] [PATCH v3 05/11] qemu-thread: add simple test-and-set spinlock, Emilio G. Cota, 2016/04/20
- Re: [Qemu-devel] [PATCH v3 05/11] qemu-thread: add simple test-and-set spinlock, Richard Henderson, 2016/04/20
- Re: [Qemu-devel] [PATCH v3 05/11] qemu-thread: add simple test-and-set spinlock, Emilio G. Cota, 2016/04/21
[Qemu-devel] [UPDATED v3 05/11] qemu-thread: add simple test-and-set spinlock,
Emilio G. Cota <=
[Qemu-devel] [PATCH v3 04/11] include/processor.h: define cpu_relax(), Emilio G. Cota, 2016/04/19
[Qemu-devel] [UPDATED v3 04/11] include/processor.h: define cpu_relax(), Emilio G. Cota, 2016/04/20
Re: [Qemu-devel] [PATCH v3 04/11] include/processor.h: define cpu_relax(), Alex Bennée, 2016/04/22
[Qemu-devel] [PATCH v3 03/11] seqlock: rename write_lock/unlock to write_begin/end, Emilio G. Cota, 2016/04/19
[Qemu-devel] [PATCH v3 10/11] tb hash: track translated blocks with qht, Emilio G. Cota, 2016/04/19
[Qemu-devel] [PATCH v3 07/11] tb hash: hash phys_pc, pc, and flags with xxhash, Emilio G. Cota, 2016/04/19