ensure that callbacks are outside of RCU critical sections

src/server/ua_services_attribute.c

@@ -402,8 +402,10 @@ static UA_StatusCode
 readValueAttributeFromNode(UA_Server *server, const UA_VariableNode *vn, UA_DataValue *v,
                            UA_NumericRange *rangeptr) {
     if(vn->value.data.callback.onRead) {
+        UA_RCU_UNLOCK();
         vn->value.data.callback.onRead(vn->value.data.callback.handle,
                                        vn->nodeId, &vn->value.data.value.value, rangeptr);
+        UA_RCU_LOCK();
 #ifdef UA_ENABLE_MULTITHREADING
         /* Reopen the node to see the changes (multithreading only) */
         vn = (const UA_VariableNode*)UA_NodeStore_get(server->nodestore, &vn->nodeId);
@@ -424,8 +426,13 @@ readValueAttributeFromDataSource(const UA_VariableNode *vn, UA_DataValue *v,
         return UA_STATUSCODE_BADINTERNALERROR;
     UA_Boolean sourceTimeStamp = (timestamps == UA_TIMESTAMPSTORETURN_SOURCE ||
                                   timestamps == UA_TIMESTAMPSTORETURN_BOTH);
-    return vn->value.dataSource.read(vn->value.dataSource.handle, vn->nodeId,
-                                     sourceTimeStamp, rangeptr, v);
+
+    UA_RCU_UNLOCK();
+    UA_StatusCode retval =
+        vn->value.dataSource.read(vn->value.dataSource.handle, vn->nodeId,
+                                  sourceTimeStamp, rangeptr, v);
+    UA_RCU_LOCK();
+    return retval;
 }
 
 static UA_StatusCode
@@ -555,15 +562,21 @@ writeValueAttribute(UA_Server *server, UA_VariableNode *node,
             writtenNode = node; /* The node is written in-situ (TODO: this might
                                    change with the nodestore plugin approach) */
 #endif
-            writtenNode->value.data.callback.onWrite(writtenNode->value.data.callback.handle, writtenNode->nodeId,
+            UA_RCU_UNLOCK();
+            writtenNode->value.data.callback.onWrite(writtenNode->value.data.callback.handle,
+                                                     writtenNode->nodeId,
                                                      &writtenNode->value.data.value.value, rangeptr);
+            UA_RCU_LOCK();
         }
     } else {
-        if(node->value.dataSource.write)
+        if(node->value.dataSource.write) {
+            UA_RCU_UNLOCK();
             retval = node->value.dataSource.write(node->value.dataSource.handle,
                                                   node->nodeId, &editableValue.value, rangeptr);
-        else
+            UA_RCU_LOCK();
+        } else {
             retval = UA_STATUSCODE_BADWRITENOTSUPPORTED;
+        }
     }
 
     /* Clean up */