From: Phil Yang <phil.y...@arm.com>
The runstate, comp_runstate and app_runstate are used as guard variables
in the service core lib. To guarantee the inter-threads visibility of
these guard variables, it uses rte_smp_r/wmb. This patch use c11 atomic
built-ins to relax these barriers.
Signed-off-by: Phil Yang <phil.y...@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>
---
lib/librte_eal/common/rte_service.c | 115 ++++++++++++++++++++--------
1 file changed, 84 insertions(+), 31 deletions(-)
diff --git a/lib/librte_eal/common/rte_service.c
b/lib/librte_eal/common/rte_service.c
index 8cac265c9..dbb821139 100644
--- a/lib/librte_eal/common/rte_service.c
+++ b/lib/librte_eal/common/rte_service.c
@@ -265,7 +265,6 @@ rte_service_component_register(const struct
rte_service_spec *spec,
s->spec = *spec;
s->internal_flags |= SERVICE_F_REGISTERED | SERVICE_F_START_CHECK;
- rte_smp_wmb();
rte_service_count++;
if (id_ptr)
@@ -282,7 +281,6 @@ rte_service_component_unregister(uint32_t id)
SERVICE_VALID_GET_OR_ERR_RET(id, s, -EINVAL);
rte_service_count--;
- rte_smp_wmb();
s->internal_flags &= ~(SERVICE_F_REGISTERED);
@@ -301,12 +299,17 @@ rte_service_component_runstate_set(uint32_t id, uint32_t
runstate)
struct rte_service_spec_impl *s;
SERVICE_VALID_GET_OR_ERR_RET(id, s, -EINVAL);
+ /* comp_runstate act as the guard variable. Use store-release
+ * memory order. This synchronizes with load-acquire in
+ * service_run and service_runstate_get function.
+ */
if (runstate)
- s->comp_runstate = RUNSTATE_RUNNING;
+ __atomic_store_n(&s->comp_runstate, RUNSTATE_RUNNING,
+ __ATOMIC_RELEASE);
else
- s->comp_runstate = RUNSTATE_STOPPED;
+ __atomic_store_n(&s->comp_runstate, RUNSTATE_STOPPED,
+ __ATOMIC_RELEASE);
- rte_smp_wmb();
return 0;
}
@@ -316,12 +319,17 @@ rte_service_runstate_set(uint32_t id, uint32_t runstate)
struct rte_service_spec_impl *s;
SERVICE_VALID_GET_OR_ERR_RET(id, s, -EINVAL);
+ /* app_runstate act as the guard variable. Use store-release
+ * memory order. This synchronizes with load-acquire in
+ * service_run runstate_get function.
+ */
if (runstate)
- s->app_runstate = RUNSTATE_RUNNING;
+ __atomic_store_n(&s->app_runstate, RUNSTATE_RUNNING,
+ __ATOMIC_RELEASE);
else
- s->app_runstate = RUNSTATE_STOPPED;
+ __atomic_store_n(&s->app_runstate, RUNSTATE_STOPPED,
+ __ATOMIC_RELEASE);
- rte_smp_wmb();
return 0;
}
@@ -330,15 +338,24 @@ rte_service_runstate_get(uint32_t id)
{
struct rte_service_spec_impl *s;
SERVICE_VALID_GET_OR_ERR_RET(id, s, -EINVAL);
- rte_smp_rmb();
- int check_disabled = !(s->internal_flags & SERVICE_F_START_CHECK);
- int lcore_mapped = (__atomic_load_n(&s->num_mapped_cores,
+ /* comp_runstate and app_runstate act as the guard variables.
+ * Use load-acquire memory order. This synchronizes with
+ * store-release in service state set functions.
+ */
+ if (__atomic_load_n(&s->comp_runstate,
+ __ATOMIC_ACQUIRE) == RUNSTATE_RUNNING &&
+ __atomic_load_n(&s->app_runstate,
+ __ATOMIC_ACQUIRE) == RUNSTATE_RUNNING) {
+ int check_disabled = !(s->internal_flags &
+ SERVICE_F_START_CHECK);
+ int lcore_mapped = (__atomic_load_n(&s->num_mapped_cores,
__ATOMIC_RELAXED) > 0);
- return (s->app_runstate == RUNSTATE_RUNNING) &&
- (s->comp_runstate == RUNSTATE_RUNNING) &&
- (check_disabled | lcore_mapped);
+ return (check_disabled | lcore_mapped);
+ } else
+ return 0;
+
}
static inline void
@@ -367,9 +384,15 @@ service_run(uint32_t i, struct core_state *cs, uint64_t
service_mask,
if (!s)
return -EINVAL;
- if (s->comp_runstate != RUNSTATE_RUNNING ||
- s->app_runstate != RUNSTATE_RUNNING ||
- !(service_mask & (UINT64_C(1) << i))) {
+ /* comp_runstate and app_runstate act as the guard variables.
+ * Use load-acquire memory order. This synchronizes with
+ * store-release in service state set functions.
+ */
+ if (__atomic_load_n(&s->comp_runstate,
+ __ATOMIC_ACQUIRE) != RUNSTATE_RUNNING ||
+ __atomic_load_n(&s->app_runstate,
+ __ATOMIC_ACQUIRE) != RUNSTATE_RUNNING ||
+ !(service_mask & (UINT64_C(1) << i))) {
cs->service_active_on_lcore[i] = 0;
return -ENOEXEC;
}
@@ -434,7 +457,12 @@ service_runner_func(void *arg)
const int lcore = rte_lcore_id();
struct core_state *cs = &lcore_states[lcore];
- while (cs->runstate == RUNSTATE_RUNNING) {
+ /* runstate act as the guard variable. Use load-acquire
+ * memory order here to synchronize with store-release
+ * in runstate update functions.
+ */
+ while (__atomic_load_n(&cs->runstate,
+ __ATOMIC_ACQUIRE) == RUNSTATE_RUNNING) {
const uint64_t service_mask = cs->service_mask;
for (i = 0; i < RTE_SERVICE_NUM_MAX; i++) {
@@ -445,8 +473,6 @@ service_runner_func(void *arg)
}
cs->loops++;
-
- rte_smp_rmb();
}
lcore_config[lcore].state = WAIT;
@@ -614,15 +640,18 @@ rte_service_lcore_reset_all(void)
if (lcore_states[i].is_service_core) {
lcore_states[i].service_mask = 0;
set_lcore_state(i, ROLE_RTE);
- lcore_states[i].runstate = RUNSTATE_STOPPED;
+ /* runstate act as guard variable Use
+ * store-release memory order here to synchronize
+ * with load-acquire in runstate read functions.
+ */
+ __atomic_store_n(&lcore_states[i].runstate,
+ RUNSTATE_STOPPED, __ATOMIC_RELEASE);
}
}
for (i = 0; i < RTE_SERVICE_NUM_MAX; i++)
__atomic_store_n(&rte_services[i].num_mapped_cores, 0,
__ATOMIC_RELAXED);
- rte_smp_wmb();
-
return 0;
}
@@ -638,9 +667,11 @@ rte_service_lcore_add(uint32_t lcore)
/* ensure that after adding a core the mask and state are defaults */
lcore_states[lcore].service_mask = 0;
- lcore_states[lcore].runstate = RUNSTATE_STOPPED;
-
- rte_smp_wmb();
+ /* Use store-release memory order here to synchronize with
+ * load-acquire in runstate read functions.
+ */
+ __atomic_store_n(&lcore_states[lcore].runstate, RUNSTATE_STOPPED,
+ __ATOMIC_RELEASE);
return rte_eal_wait_lcore(lcore);
}
@@ -655,7 +686,12 @@ rte_service_lcore_del(uint32_t lcore)
if (!cs->is_service_core)
return -EINVAL;
- if (cs->runstate != RUNSTATE_STOPPED)
+ /* runstate act as the guard variable. Use load-acquire
+ * memory order here to synchronize with store-release
+ * in runstate update functions.
+ */
+ if (__atomic_load_n(&cs->runstate,
+ __ATOMIC_ACQUIRE) != RUNSTATE_STOPPED)
return -EBUSY;
set_lcore_state(lcore, ROLE_RTE);
@@ -674,13 +710,21 @@ rte_service_lcore_start(uint32_t lcore)
if (!cs->is_service_core)
return -EINVAL;
- if (cs->runstate == RUNSTATE_RUNNING)
+ /* runstate act as the guard variable. Use load-acquire
+ * memory order here to synchronize with store-release
+ * in runstate update functions.
+ */
+ if (__atomic_load_n(&cs->runstate,
+ __ATOMIC_ACQUIRE) == RUNSTATE_RUNNING)
return -EALREADY;
/* set core to run state first, and then launch otherwise it will
* return immediately as runstate keeps it in the service poll loop
*/
- cs->runstate = RUNSTATE_RUNNING;
+ /* Use load-acquire memory order here to synchronize with
+ * store-release in runstate update functions.
+ */
+ __atomic_store_n(&cs->runstate, RUNSTATE_RUNNING, __ATOMIC_RELEASE);
int ret = rte_eal_remote_launch(service_runner_func, 0, lcore);
/* returns -EBUSY if the core is already launched, 0 on success */
@@ -693,7 +737,12 @@ rte_service_lcore_stop(uint32_t lcore)
if (lcore >= RTE_MAX_LCORE)
return -EINVAL;
- if (lcore_states[lcore].runstate == RUNSTATE_STOPPED)
+ /* runstate act as the guard variable. Use load-acquire
+ * memory order here to synchronize with store-release
+ * in runstate update functions.
+ */
+ if (__atomic_load_n(&lcore_states[lcore].runstate,
+ __ATOMIC_ACQUIRE) == RUNSTATE_STOPPED)
return -EALREADY;
uint32_t i;
@@ -713,7 +762,11 @@ rte_service_lcore_stop(uint32_t lcore)
return -EBUSY;
}
- lcore_states[lcore].runstate = RUNSTATE_STOPPED;
+ /* Use store-release memory order here to synchronize with
+ * load-acquire in runstate read functions.
+ */
+ __atomic_store_n(&lcore_states[lcore].runstate, RUNSTATE_STOPPED,
+ __ATOMIC_RELEASE);
return 0;
}
--
2.17.1
