Fix: event notifier create protocol order issue

[lttng-ust.git] / liblttng-ust / lttng-ust-abi.c

diff --git a/liblttng-ust/lttng-ust-abi.c b/liblttng-ust/lttng-ust-abi.c
index 0d2058a3f5947b24eb604c88a0f1c5a20e880a1b..b35065996815a1cc3c8fd56aac47a6f6471018e6 100644 (file)
--- a/liblttng-ust/lttng-ust-abi.c
+++ b/liblttng-ust/lttng-ust-abi.c
@@ -57,6 +57,7 @@
 #include "../libringbuffer/frontend_types.h"
 #include "../libringbuffer/shm.h"
 #include "../libcounter/counter.h"
+#include "tracepoint-internal.h"
 #include "lttng-tracer.h"
 #include "string-utils.h"
 #include "ust-events-internal.h"
@@ -438,7 +439,7 @@ long lttng_cmd(int objd, unsigned int cmd, unsigned long arg,
        case LTTNG_UST_TRACEPOINT_FIELD_LIST:
                return lttng_abi_tracepoint_field_list(owner);
        case LTTNG_UST_WAIT_QUIESCENT:
-               synchronize_trace();
+               lttng_ust_synchronize_trace();
                return 0;
        case LTTNG_UST_EVENT_NOTIFIER_GROUP_CREATE:
                return lttng_abi_event_notifier_send_fd(owner,
@@ -815,10 +816,10 @@ int lttng_ust_event_notifier_group_create_error_counter(int event_notifier_group
                return -EINVAL;
 
        switch (error_counter_conf->bitness) {
-       case LTTNG_UST_COUNTER_BITNESS_64BITS:
+       case LTTNG_UST_COUNTER_BITNESS_64:
                counter_transport_name = "counter-per-cpu-64-modular";
                break;
-       case LTTNG_UST_COUNTER_BITNESS_32BITS:
+       case LTTNG_UST_COUNTER_BITNESS_32:
                counter_transport_name = "counter-per-cpu-32-modular";
                break;
        default:
@@ -845,8 +846,16 @@ int lttng_ust_event_notifier_group_create_error_counter(int event_notifier_group
                goto create_error;
        }
 
-       event_notifier_group->error_counter = counter;
        event_notifier_group->error_counter_len = counter_len;
+       /*
+        * store-release to publish error counter matches load-acquire
+        * in record_error. Ensures the counter is created and the
+        * error_counter_len is set before they are used.
+        * Currently a full memory barrier is used, which could be
+        * turned into acquire-release barriers.
+        */
+       cmm_smp_mb();
+       CMM_STORE_SHARED(event_notifier_group->error_counter, counter);
 
        counter->objd = counter_objd;
        counter->event_notifier_group = event_notifier_group;   /* owner */