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.nagaraha...@arm.com>
Reviewed-by: Feifei Wang <feifei.w...@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
