UCX: fix problem when doing multiple session init/finalize

Another case where the MCA system gets shut down if no more "instances" are present,
but unless --enable-mca-dso is used, the UCX common has retained info about memory
allocation, etc. that is no longer correct.

related to #12909

Signed-off-by: Howard Pritchard <[email protected]>

opal/mca/common/ucx/common_ucx.c

@@ -4,7 +4,7 @@
  * Copyright (c) 2019      Intel, Inc.  All rights reserved.
  * Copyright (c) 2019      Research Organization for Information Science
  *                         and Technology (RIST).  All rights reserved.
- * Copyright (c) 2021      Triad National Security, LLC. All rights
+ * Copyright (c) 2021-2024 Triad National Security, LLC. All rights
  *                         reserved.
  * Copyright (c) 2022      Google, LLC. All rights reserved.
  * Copyright (c) 2022      IBM Corporation.  All rights reserved.
@@ -107,6 +107,10 @@ OPAL_DECLSPEC void opal_common_ucx_mca_var_register(const mca_base_component_t *
         // cleans up the MCA vars. This will cause the string to go
         // out of scope unless we place the pointer to it on the heap.
         opal_common_ucx.tls = (char **) malloc(sizeof(char *));
+        *opal_common_ucx.tls = NULL;
+    }
+
+    if (NULL == *opal_common_ucx.tls) {
         *opal_common_ucx.tls = strdup(default_tls);
     }
 
@@ -122,8 +126,13 @@ OPAL_DECLSPEC void opal_common_ucx_mca_var_register(const mca_base_component_t *
 
     if (NULL == opal_common_ucx.devices) {
         opal_common_ucx.devices = (char**) malloc(sizeof(char*));
+        *opal_common_ucx.devices = NULL;
+    }
+
+    if (NULL == *opal_common_ucx.devices) {
         *opal_common_ucx.devices = strdup(default_devices);
     }
+
     devices_index = mca_base_var_register(
         "opal", "opal_common", "ucx", "devices",
         "List of device driver pattern names, which, if supported by UCX, will "