From: "Ondřej Surý via lttng-dev" <lttng-dev@lists.lttng.org>
To: lttng-dev@lists.lttng.org
Subject: [lttng-dev] [PATCH 5/7] Use __atomic builtins to implement CMM_{LOAD, STORE}_SHARED
Date: Fri, 17 Mar 2023 22:37:53 +0100 [thread overview]
Message-ID: <20230317213755.455957-6-ondrej@sury.org> (raw)
In-Reply-To: <20230317213755.455957-1-ondrej@sury.org>
Instead of using CMM_ACCESS_ONCE() with memory barriers, use __atomic
builtins with relaxed memory ordering to implement CMM_LOAD_SHARED() and
CMM_STORE_SHARED().
Signed-off-by: Ondřej Surý <ondrej@sury.org>
---
include/urcu/system.h | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/include/urcu/system.h b/include/urcu/system.h
index faae390..99e7443 100644
--- a/include/urcu/system.h
+++ b/include/urcu/system.h
@@ -26,7 +26,7 @@
* Identify a shared load. A cmm_smp_rmc() or cmm_smp_mc() should come
* before the load.
*/
-#define _CMM_LOAD_SHARED(p) CMM_ACCESS_ONCE(p)
+#define _CMM_LOAD_SHARED(p) __atomic_load_n(&(p), __ATOMIC_RELAXED)
/*
* Load a data from shared memory, doing a cache flush if required.
@@ -42,7 +42,7 @@
* Identify a shared store. A cmm_smp_wmc() or cmm_smp_mc() should
* follow the store.
*/
-#define _CMM_STORE_SHARED(x, v) __extension__ ({ CMM_ACCESS_ONCE(x) = (v); })
+#define _CMM_STORE_SHARED(x, v) __atomic_store_n(&(x), (v), __ATOMIC_RELAXED)
/*
* Store v into x, where x is located in shared memory. Performs the
@@ -51,9 +51,8 @@
#define CMM_STORE_SHARED(x, v) \
__extension__ \
({ \
- __typeof__(x) _v = _CMM_STORE_SHARED(x, v); \
+ _CMM_STORE_SHARED(x, v); \
cmm_smp_wmc(); \
- _v = _v; /* Work around clang "unused result" */ \
})
#endif /* _URCU_SYSTEM_H */
--
2.39.2
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next prev parent reply other threads:[~2023-03-17 21:38 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-17 21:37 [lttng-dev] [PATCH 0/7] Replace the custom code with gcc/clang __atomic builtins Ondřej Surý via lttng-dev
2023-03-17 21:37 ` [lttng-dev] [PATCH 1/7] Require __atomic builtins to build Ondřej Surý via lttng-dev
2023-03-17 21:37 ` [lttng-dev] [PATCH 2/7] Use gcc __atomic builtis for <urcu/uatomic.h> implementation Ondřej Surý via lttng-dev
2023-03-20 18:03 ` Mathieu Desnoyers via lttng-dev
2023-03-20 18:13 ` Mathieu Desnoyers via lttng-dev
2023-03-20 18:28 ` Ondřej Surý via lttng-dev
2023-03-20 18:38 ` Mathieu Desnoyers via lttng-dev
2023-03-20 18:41 ` Mathieu Desnoyers via lttng-dev
2023-03-20 19:38 ` Duncan Sands via lttng-dev
2023-03-21 20:26 ` Mathieu Desnoyers via lttng-dev
2023-03-22 8:24 ` Duncan Sands via lttng-dev
2023-03-17 21:37 ` [lttng-dev] [PATCH 3/7] Use __atomic_thread_fence() for cmm_barrier() Ondřej Surý via lttng-dev
2023-03-20 18:06 ` Mathieu Desnoyers via lttng-dev
2023-03-20 18:14 ` Mathieu Desnoyers via lttng-dev
2023-03-17 21:37 ` [lttng-dev] [PATCH 4/7] Replace the internal pointer manipulation with __atomic builtins Ondřej Surý via lttng-dev
2023-03-20 18:25 ` Mathieu Desnoyers via lttng-dev
2023-03-17 21:37 ` Ondřej Surý via lttng-dev [this message]
2023-03-20 18:28 ` [lttng-dev] [PATCH 5/7] Use __atomic builtins to implement CMM_{LOAD, STORE}_SHARED Mathieu Desnoyers via lttng-dev
2023-03-17 21:37 ` [lttng-dev] [PATCH 6/7] Fix: uatomic_or() need retyping to uintptr_t in rculfhash.c Ondřej Surý via lttng-dev
2023-03-20 18:31 ` Mathieu Desnoyers via lttng-dev
2023-03-21 10:15 ` Ondřej Surý via lttng-dev
2023-03-21 14:44 ` Mathieu Desnoyers via lttng-dev
2023-03-21 14:45 ` Mathieu Desnoyers via lttng-dev
2023-03-17 21:37 ` [lttng-dev] [PATCH 7/7] Experiment: Add explicit memory barrier in free_completion() Ondřej Surý via lttng-dev
2023-03-20 18:37 ` Mathieu Desnoyers via lttng-dev
2023-03-21 10:21 ` Ondřej Surý via lttng-dev
2023-03-21 14:46 ` Mathieu Desnoyers via lttng-dev
2023-03-21 14:48 ` Ondřej Surý via lttng-dev
2023-03-21 14:49 ` Mathieu Desnoyers via lttng-dev
2023-03-21 14:59 ` [lttng-dev] TSAN and the tests Ondřej Surý via lttng-dev
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