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From: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
To: dev@dpdk.org, honnappa.nagarahalli@arm.com,
	konstantin.ananyev@intel.com, david.marchand@redhat.com,
	feifei.wang2@arm.com
Cc: ruifeng.wang@arm.com, nd@arm.com, Feifei Wang <feifei.wang@arm.com>
Subject: [dpdk-dev] [PATCH v2 5/6] eal: ensure memory operations are visible to main
Date: Thu,  9 Sep 2021 18:13:11 -0500	[thread overview]
Message-ID: <20210909231312.2572006-6-honnappa.nagarahalli@arm.com> (raw)
In-Reply-To: <20210909231312.2572006-1-honnappa.nagarahalli@arm.com>

Ensure that the memory operations in worker thread, that happen
before it returns the status of the assigned function, are
visible to the main thread.

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Feifei Wang <feifei.wang@arm.com>
---
 lib/eal/common/eal_common_launch.c |  2 --
 lib/eal/freebsd/eal_thread.c       | 22 ++++++++++++++++++----
 lib/eal/linux/eal_thread.c         | 23 ++++++++++++++++++-----
 lib/eal/windows/eal_thread.c       | 21 +++++++++++++++++----
 4 files changed, 53 insertions(+), 15 deletions(-)

diff --git a/lib/eal/common/eal_common_launch.c b/lib/eal/common/eal_common_launch.c
index 4bc842417a..e95dadffb3 100644
--- a/lib/eal/common/eal_common_launch.c
+++ b/lib/eal/common/eal_common_launch.c
@@ -27,8 +27,6 @@ rte_eal_wait_lcore(unsigned worker_id)
 					__ATOMIC_ACQUIRE) != WAIT)
 		rte_pause();
 
-	rte_rmb();
-
 	return lcore_config[worker_id].ret;
 }
 
diff --git a/lib/eal/freebsd/eal_thread.c b/lib/eal/freebsd/eal_thread.c
index e5e3edf79b..3b18030d73 100644
--- a/lib/eal/freebsd/eal_thread.c
+++ b/lib/eal/freebsd/eal_thread.c
@@ -39,7 +39,11 @@ rte_eal_remote_launch(int (*f)(void *), void *arg, unsigned worker_id)
 	int w2m = lcore_config[worker_id].pipe_worker2main[0];
 	int rc = -EBUSY;
 
-	if (lcore_config[worker_id].state != WAIT)
+	/* Check if the worker is in 'WAIT' state. Use acquire order
+	 * since 'state' variable is used as the guard variable.
+	 */
+	if (__atomic_load_n(&lcore_config[worker_id].state,
+					__ATOMIC_ACQUIRE) != WAIT)
 		goto finish;
 
 	lcore_config[worker_id].arg = arg;
@@ -115,7 +119,11 @@ eal_thread_loop(__rte_unused void *arg)
 		if (n <= 0)
 			rte_panic("cannot read on configuration pipe\n");
 
-		lcore_config[lcore_id].state = RUNNING;
+		/* Set the state to 'RUNNING'. Use release order
+		 * since 'state' variable is used as the guard variable.
+		 */
+		__atomic_store_n(&lcore_config[lcore_id].state, RUNNING,
+					__ATOMIC_RELEASE);
 
 		/* send ack */
 		n = 0;
@@ -139,8 +147,14 @@ eal_thread_loop(__rte_unused void *arg)
 		lcore_config[lcore_id].ret = ret;
 		lcore_config[lcore_id].f = NULL;
 		lcore_config[lcore_id].arg = NULL;
-		rte_wmb();
-		lcore_config[lcore_id].state = WAIT;
+
+		/* Store the state with release order to ensure that
+		 * the memory operations from the worker thread
+		 * are completed before the state is updated.
+		 * Use 'state' as the guard variable.
+		 */
+		__atomic_store_n(&lcore_config[lcore_id].state, WAIT,
+					__ATOMIC_RELEASE);
 	}
 
 	/* never reached */
diff --git a/lib/eal/linux/eal_thread.c b/lib/eal/linux/eal_thread.c
index c79e09c9ad..c7f0f9b2f7 100644
--- a/lib/eal/linux/eal_thread.c
+++ b/lib/eal/linux/eal_thread.c
@@ -39,13 +39,17 @@ rte_eal_remote_launch(int (*f)(void *), void *arg, unsigned int worker_id)
 	int w2m = lcore_config[worker_id].pipe_worker2main[0];
 	int rc = -EBUSY;
 
-	if (lcore_config[worker_id].state != WAIT)
+	/* Check if the worker is in 'WAIT' state. Use acquire order
+	 * since 'state' variable is used as the guard variable.
+	 */
+	if (__atomic_load_n(&lcore_config[worker_id].state,
+					__ATOMIC_ACQUIRE) != WAIT)
 		goto finish;
 
 	lcore_config[worker_id].arg = arg;
 	/* Ensure that all the memory operations are completed
 	 * before the worker thread starts running the function.
-	 * Use worker thread function as the guard variable.
+	 * Use worker thread function pointer as the guard variable.
 	 */
 	__atomic_store_n(&lcore_config[worker_id].f, f, __ATOMIC_RELEASE);
 
@@ -115,7 +119,11 @@ eal_thread_loop(__rte_unused void *arg)
 		if (n <= 0)
 			rte_panic("cannot read on configuration pipe\n");
 
-		lcore_config[lcore_id].state = RUNNING;
+		/* Set the state to 'RUNNING'. Use release order
+		 * since 'state' variable is used as the guard variable.
+		 */
+		__atomic_store_n(&lcore_config[lcore_id].state, RUNNING,
+					__ATOMIC_RELEASE);
 
 		/* send ack */
 		n = 0;
@@ -139,9 +147,14 @@ eal_thread_loop(__rte_unused void *arg)
 		lcore_config[lcore_id].ret = ret;
 		lcore_config[lcore_id].f = NULL;
 		lcore_config[lcore_id].arg = NULL;
-		rte_wmb();
 
-		lcore_config[lcore_id].state = WAIT;
+		/* Store the state with release order to ensure that
+		 * the memory operations from the worker thread
+		 * are completed before the state is updated.
+		 * Use 'state' as the guard variable.
+		 */
+		__atomic_store_n(&lcore_config[lcore_id].state, WAIT,
+					__ATOMIC_RELEASE);
 	}
 
 	/* never reached */
diff --git a/lib/eal/windows/eal_thread.c b/lib/eal/windows/eal_thread.c
index 977911905e..54fa93fa62 100644
--- a/lib/eal/windows/eal_thread.c
+++ b/lib/eal/windows/eal_thread.c
@@ -29,7 +29,11 @@ rte_eal_remote_launch(lcore_function_t *f, void *arg, unsigned int worker_id)
 	int m2w = lcore_config[worker_id].pipe_main2worker[1];
 	int w2m = lcore_config[worker_id].pipe_worker2main[0];
 
-	if (lcore_config[worker_id].state != WAIT)
+	/* Check if the worker is in 'WAIT' state. Use acquire order
+	 * since 'state' variable is used as the guard variable.
+	 */
+	if (__atomic_load_n(&lcore_config[worker_id].state,
+					__ATOMIC_ACQUIRE) != WAIT)
 		return -EBUSY;
 
 	lcore_config[worker_id].arg = arg;
@@ -99,7 +103,11 @@ eal_thread_loop(void *arg __rte_unused)
 		if (n <= 0)
 			rte_panic("cannot read on configuration pipe\n");
 
-		lcore_config[lcore_id].state = RUNNING;
+		/* Set the state to 'RUNNING'. Use release order
+		 * since 'state' variable is used as the guard variable.
+		 */
+		__atomic_store_n(&lcore_config[lcore_id].state, RUNNING,
+					__ATOMIC_RELEASE);
 
 		/* send ack */
 		n = 0;
@@ -123,9 +131,14 @@ eal_thread_loop(void *arg __rte_unused)
 		lcore_config[lcore_id].ret = ret;
 		lcore_config[lcore_id].f = NULL;
 		lcore_config[lcore_id].arg = NULL;
-		rte_wmb();
 
-		lcore_config[lcore_id].state = WAIT;
+		/* Store the state with release order to ensure that
+		 * the memory operations from the worker thread
+		 * are completed before the state is updated.
+		 * Use 'state' as the guard variable.
+		 */
+		__atomic_store_n(&lcore_config[lcore_id].state, WAIT,
+					__ATOMIC_RELEASE);
 	}
 }
 
-- 
2.25.1


  parent reply	other threads:[~2021-09-09 23:14 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-24 21:20 [dpdk-dev] [RFC 0/5] Use correct memory ordering in eal functions Honnappa Nagarahalli
2021-02-24 21:20 ` [dpdk-dev] [RFC 1/5] eal: reset lcore function pointer and argument Honnappa Nagarahalli
2021-02-24 21:20 ` [dpdk-dev] [RFC 2/5] eal: ensure memory operations are visible to worker Honnappa Nagarahalli
2021-02-24 21:20 ` [dpdk-dev] [RFC 3/5] eal: lcore state FINISHED is not required Honnappa Nagarahalli
     [not found]   ` <AM5PR0802MB2465B62994239817E0AC46C59E9E9@AM5PR0802MB2465.eurprd08.prod.outlook.com>
2021-02-25  8:44     ` [dpdk-dev] 回复: " Feifei Wang
2021-02-25 23:33       ` [dpdk-dev] " Honnappa Nagarahalli
2021-02-26  8:26         ` Thomas Monjalon
2021-03-02  3:13           ` Honnappa Nagarahalli
2021-03-19 13:42             ` Ananyev, Konstantin
2021-03-30  2:54               ` Honnappa Nagarahalli
2021-03-01  5:55         ` [dpdk-dev] 回复: " Feifei Wang
2021-02-24 21:20 ` [dpdk-dev] [RFC 4/5] eal: ensure memory operations are visible to main Honnappa Nagarahalli
2021-02-24 21:20 ` [dpdk-dev] [RFC 5/5] test/ring: use relaxed barriers for ring stress test Honnappa Nagarahalli
2021-03-01 16:41 ` [dpdk-dev] [RFC 0/5] Use correct memory ordering in eal functions Stephen Hemminger
2021-03-02 16:06   ` Honnappa Nagarahalli
2021-09-09 23:13 ` [dpdk-dev] [PATCH v2 0/6] " Honnappa Nagarahalli
2021-09-09 23:13   ` [dpdk-dev] [PATCH v2 1/6] eal: reset lcore function pointer and argument Honnappa Nagarahalli
2021-09-10  7:49     ` Bruce Richardson
2021-09-10  8:12       ` David Marchand
2021-09-11 22:19         ` Honnappa Nagarahalli
2021-09-09 23:13   ` [dpdk-dev] [PATCH v2 2/6] eal: ensure memory operations are visible to worker Honnappa Nagarahalli
2021-09-09 23:13   ` [dpdk-dev] [PATCH v2 3/6] eal: lcore state FINISHED is not required Honnappa Nagarahalli
2021-09-09 23:13   ` [dpdk-dev] [PATCH v2 4/6] eal: update rte_eal_wait_lcore definition Honnappa Nagarahalli
2021-09-09 23:37     ` Honnappa Nagarahalli
2021-09-09 23:13   ` Honnappa Nagarahalli [this message]
2021-09-09 23:13   ` [dpdk-dev] [PATCH v2 6/6] test/ring: use relaxed barriers for ring stress test Honnappa Nagarahalli
2021-10-07 11:55     ` Ananyev, Konstantin
2021-10-07 23:40       ` Honnappa Nagarahalli
2021-10-25  4:52 ` [dpdk-dev] [PATCH v3 0/4] Use correct memory ordering in eal functions Honnappa Nagarahalli
2021-10-25  4:52   ` [dpdk-dev] [PATCH v3 1/4] eal: reset lcore function pointer and argument Honnappa Nagarahalli
2021-10-25  4:52   ` [dpdk-dev] [PATCH v3 2/4] eal: lcore state FINISHED is not required Honnappa Nagarahalli
2021-10-25  4:52   ` [dpdk-dev] [PATCH v3 3/4] eal: use correct memory ordering Honnappa Nagarahalli
2021-10-25  4:52   ` [dpdk-dev] [PATCH v3 4/4] test/ring: use relaxed barriers for ring stress test Honnappa Nagarahalli
2021-10-25 16:23   ` [dpdk-dev] [PATCH v3 0/4] Use correct memory ordering in eal functions David Marchand

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