From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49817) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b5NOn-0001lh-Bw for qemu-devel@nongnu.org; Tue, 24 May 2016 21:14:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b5NOH-0007fT-Px for qemu-devel@nongnu.org; Tue, 24 May 2016 21:14:13 -0400 Received: from out2-smtp.messagingengine.com ([66.111.4.26]:37495) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b5NOF-0007cM-EH for qemu-devel@nongnu.org; Tue, 24 May 2016 21:13:41 -0400 From: "Emilio G. Cota" Date: Tue, 24 May 2016 21:13:12 -0400 Message-Id: <1464138802-23503-6-git-send-email-cota@braap.org> In-Reply-To: <1464138802-23503-1-git-send-email-cota@braap.org> References: <1464138802-23503-1-git-send-email-cota@braap.org> Subject: [Qemu-devel] [PATCH v6 05/15] qemu-thread: add simple test-and-set spinlock List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: QEMU Developers , MTTCG Devel Cc: =?UTF-8?q?Alex=20Benn=C3=A9e?= , Paolo Bonzini , Richard Henderson , Sergey Fedorov From: Guillaume Delbergue Signed-off-by: Guillaume Delbergue [Rewritten. - Paolo] Signed-off-by: Paolo Bonzini [Emilio's additions: use TAS instead of atomic_xchg; emit acquire/release barriers; return bool from trylock; call cpu_relax() while spinning; optimize for uncontended locks by acquiring the lock with TAS instead of TATAS; add qemu_spin_locked().] Signed-off-by: Emilio G. Cota --- include/qemu/thread.h | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/include/qemu/thread.h b/include/qemu/thread.h index bdae6df..c5d71cf 100644 --- a/include/qemu/thread.h +++ b/include/qemu/thread.h @@ -1,6 +1,8 @@ #ifndef __QEMU_THREAD_H #define __QEMU_THREAD_H 1 +#include "qemu/processor.h" +#include "qemu/atomic.h" typedef struct QemuMutex QemuMutex; typedef struct QemuCond QemuCond; @@ -60,4 +62,37 @@ 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) +{ + __sync_lock_release(&spin->value); +} + +static inline void qemu_spin_lock(QemuSpin *spin) +{ + while (unlikely(__sync_lock_test_and_set(&spin->value, true))) { + while (atomic_read(&spin->value)) { + cpu_relax(); + } + } +} + +static inline bool qemu_spin_trylock(QemuSpin *spin) +{ + return __sync_lock_test_and_set(&spin->value, true); +} + +static inline bool qemu_spin_locked(QemuSpin *spin) +{ + return atomic_read(&spin->value); +} + +static inline void qemu_spin_unlock(QemuSpin *spin) +{ + __sync_lock_release(&spin->value); +} + #endif -- 2.5.0