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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,
	Ola Liljedahl <ola.liljedahl@arm.com>,
	Feifei Wang <feifei.wang@arm.com>
Subject: [dpdk-dev] [PATCH v2 2/6] eal: ensure memory operations are visible to worker
Date: Thu,  9 Sep 2021 18:13:08 -0500	[thread overview]
Message-ID: <20210909231312.2572006-3-honnappa.nagarahalli@arm.com> (raw)
In-Reply-To: <20210909231312.2572006-1-honnappa.nagarahalli@arm.com>

Ensure that the memory operations before the call to
rte_eal_remote_launch are visible to the worker thread.
Use the function pointer to execute in worker thread
as the guard variable.

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
Reviewed-by: Feifei Wang <feifei.wang@arm.com>
---
 lib/eal/freebsd/eal_thread.c | 19 +++++++++++++++----
 lib/eal/linux/eal_thread.c   | 19 +++++++++++++++----
 lib/eal/windows/eal_thread.c | 19 +++++++++++++++----
 3 files changed, 45 insertions(+), 12 deletions(-)

diff --git a/lib/eal/freebsd/eal_thread.c b/lib/eal/freebsd/eal_thread.c
index bbc3a8e985..17b8f39966 100644
--- a/lib/eal/freebsd/eal_thread.c
+++ b/lib/eal/freebsd/eal_thread.c
@@ -42,8 +42,12 @@ rte_eal_remote_launch(int (*f)(void *), void *arg, unsigned worker_id)
 	if (lcore_config[worker_id].state != WAIT)
 		goto finish;
 
-	lcore_config[worker_id].f = f;
 	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.
+	 */
+	__atomic_store_n(&lcore_config[worker_id].f, f, __ATOMIC_RELEASE);
 
 	/* send message */
 	n = 0;
@@ -100,6 +104,7 @@ eal_thread_loop(__rte_unused void *arg)
 
 	/* read on our pipe to get commands */
 	while (1) {
+		lcore_function_t *f;
 		void *fct_arg;
 
 		/* wait command */
@@ -119,12 +124,18 @@ eal_thread_loop(__rte_unused void *arg)
 		if (n < 0)
 			rte_panic("cannot write on configuration pipe\n");
 
-		if (lcore_config[lcore_id].f == NULL)
-			rte_panic("NULL function pointer\n");
+		/* Load 'f' with acquire order to ensure that
+		 * the memory operations from the main thread
+		 * are accessed only after update to 'f' is visible.
+		 * Wait till the update to 'f' is visible to the worker.
+		 */
+		while ((f = __atomic_load_n(&lcore_config[lcore_id].f,
+			__ATOMIC_ACQUIRE)) == NULL)
+			rte_pause();
 
 		/* call the function and store the return value */
 		fct_arg = lcore_config[lcore_id].arg;
-		ret = lcore_config[lcore_id].f(fct_arg);
+		ret = f(fct_arg);
 		lcore_config[lcore_id].ret = ret;
 		lcore_config[lcore_id].f = NULL;
 		lcore_config[lcore_id].arg = NULL;
diff --git a/lib/eal/linux/eal_thread.c b/lib/eal/linux/eal_thread.c
index 8f3c0dafd6..a0a0091040 100644
--- a/lib/eal/linux/eal_thread.c
+++ b/lib/eal/linux/eal_thread.c
@@ -42,8 +42,12 @@ rte_eal_remote_launch(int (*f)(void *), void *arg, unsigned int worker_id)
 	if (lcore_config[worker_id].state != WAIT)
 		goto finish;
 
-	lcore_config[worker_id].f = f;
 	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.
+	 */
+	__atomic_store_n(&lcore_config[worker_id].f, f, __ATOMIC_RELEASE);
 
 	/* send message */
 	n = 0;
@@ -100,6 +104,7 @@ eal_thread_loop(__rte_unused void *arg)
 
 	/* read on our pipe to get commands */
 	while (1) {
+		lcore_function_t *f;
 		void *fct_arg;
 
 		/* wait command */
@@ -119,12 +124,18 @@ eal_thread_loop(__rte_unused void *arg)
 		if (n < 0)
 			rte_panic("cannot write on configuration pipe\n");
 
-		if (lcore_config[lcore_id].f == NULL)
-			rte_panic("NULL function pointer\n");
+		/* Load 'f' with acquire order to ensure that
+		 * the memory operations from the main thread
+		 * are accessed only after update to 'f' is visible.
+		 * Wait till the update to 'f' is visible to the worker.
+		 */
+		while ((f = __atomic_load_n(&lcore_config[lcore_id].f,
+			__ATOMIC_ACQUIRE)) == NULL)
+			rte_pause();
 
 		/* call the function and store the return value */
 		fct_arg = lcore_config[lcore_id].arg;
-		ret = lcore_config[lcore_id].f(fct_arg);
+		ret = f(fct_arg);
 		lcore_config[lcore_id].ret = ret;
 		lcore_config[lcore_id].f = NULL;
 		lcore_config[lcore_id].arg = NULL;
diff --git a/lib/eal/windows/eal_thread.c b/lib/eal/windows/eal_thread.c
index df1df5d02c..e08abcf21f 100644
--- a/lib/eal/windows/eal_thread.c
+++ b/lib/eal/windows/eal_thread.c
@@ -32,8 +32,12 @@ rte_eal_remote_launch(lcore_function_t *f, void *arg, unsigned int worker_id)
 	if (lcore_config[worker_id].state != WAIT)
 		return -EBUSY;
 
-	lcore_config[worker_id].f = f;
 	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.
+	 */
+	__atomic_store_n(&lcore_config[worker_id].f, f, __ATOMIC_RELEASE);
 
 	/* send message */
 	n = 0;
@@ -84,6 +88,7 @@ eal_thread_loop(void *arg __rte_unused)
 
 	/* read on our pipe to get commands */
 	while (1) {
+		lcore_function_t *f;
 		void *fct_arg;
 
 		/* wait command */
@@ -103,12 +108,18 @@ eal_thread_loop(void *arg __rte_unused)
 		if (n < 0)
 			rte_panic("cannot write on configuration pipe\n");
 
-		if (lcore_config[lcore_id].f == NULL)
-			rte_panic("NULL function pointer\n");
+		/* Load 'f' with acquire order to ensure that
+		 * the memory operations from the main thread
+		 * are accessed only after update to 'f' is visible.
+		 * Wait till the update to 'f' is visible to the worker.
+		 */
+		while ((f = __atomic_load_n(&lcore_config[lcore_id].f,
+			__ATOMIC_ACQUIRE)) == NULL)
+			rte_pause();
 
 		/* call the function and store the return value */
 		fct_arg = lcore_config[lcore_id].arg;
-		ret = lcore_config[lcore_id].f(fct_arg);
+		ret = f(fct_arg);
 		lcore_config[lcore_id].ret = ret;
 		lcore_config[lcore_id].f = NULL;
 		lcore_config[lcore_id].arg = NULL;
-- 
2.25.1


  parent reply	other threads:[~2021-09-09 23:13 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   ` Honnappa Nagarahalli [this message]
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   ` [dpdk-dev] [PATCH v2 5/6] eal: ensure memory operations are visible to main Honnappa Nagarahalli
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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