Merge pull request #7546 from devreal/egrequest-obj-retain

grequestx: fix racy initialization and premature destruction

ompi/request/grequestx.c

@@ -30,7 +30,7 @@ static bool requests_initialized = false;
 static opal_list_t requests;
 static opal_atomic_int32_t active_requests = 0;
 static bool in_progress = false;
-static opal_mutex_t lock;
+static opal_mutex_t lock = OPAL_MUTEX_STATIC_INIT;
 
 static int grequestx_progress(void) {
     ompi_grequest_t *request, *next;
@@ -47,6 +47,7 @@ static int grequestx_progress(void) {
             OPAL_THREAD_LOCK(&lock);
             if (REQUEST_COMPLETE(&request->greq_base)) {
                 opal_list_remove_item(&requests, &request->greq_base.super.super);
+                OBJ_RELEASE(request);
                 completed++;
             }
         }
@@ -73,13 +74,17 @@ int ompi_grequestx_start(
     }
     ((ompi_grequest_t *)*request)->greq_poll.c_poll = gpoll_fn;
 
+    /* prevent the request from being destroyed upon completion,
+     * we first have to remove it from the list of active requests
+     */
+    OBJ_RETAIN(((ompi_grequest_t *)*request));
+
+    OPAL_THREAD_LOCK(&lock);
     if (!requests_initialized) {
         OBJ_CONSTRUCT(&requests, opal_list_t);
-        OBJ_CONSTRUCT(&lock, opal_mutex_t);
         requests_initialized = true;
     }
 
-    OPAL_THREAD_LOCK(&lock);
     opal_list_append(&requests, &((*request)->super.super));
     OPAL_THREAD_UNLOCK(&lock);
     int32_t tmp = OPAL_THREAD_ADD_FETCH32(&active_requests, 1);