btl/scif: start the listening thread once only

opal/mca/btl/scif/btl_scif.h

@@ -93,6 +93,7 @@ typedef struct mca_btl_scif_module_t {
     pthread_t listen_thread;
 
     volatile bool exiting;
+    bool listening;
 } mca_btl_scif_module_t;
 
 typedef struct mca_btl_scif_component_t {

opal/mca/btl/scif/btl_scif_add_procs.c

@@ -98,10 +98,13 @@ int mca_btl_scif_add_procs(struct mca_btl_base_module_t* btl,
 
     scif_module->endpoint_count = procs_on_board;
 
-    /* start listening thread */
-    rc = pthread_create (&mca_btl_scif_module.listen_thread, NULL, mca_btl_scif_connect_accept, NULL);
-    if (0 > rc) {
-        return OPAL_ERROR;
+    if (!mca_btl_scif_module.listening) {
+        /* start listening thread */
+        rc = pthread_create (&mca_btl_scif_module.listen_thread, NULL, mca_btl_scif_connect_accept, NULL);
+        if (0 > rc) {
+            return OPAL_ERROR;
+        }
+        mca_btl_scif_module.listening = true;
     }
 
     return OPAL_SUCCESS;

opal/mca/btl/scif/btl_scif_component.c

@@ -267,6 +267,7 @@ static mca_btl_base_module_t **mca_btl_scif_component_init (int *num_btl_modules
 
     base_modules[0] = &mca_btl_scif_module.super;
     mca_btl_scif_module.exiting = false;
+    mca_btl_scif_module.listening = false;
 
     rc = mca_btl_scif_modex_send ();
     if (OPAL_SUCCESS != rc) {

opal/mca/btl/scif/btl_scif_module.c

@@ -126,7 +126,7 @@ mca_btl_scif_module_finalize (struct mca_btl_base_module_t *btl)
     }
 
     /* close the listening endpoint */
-    if (-1 != mca_btl_scif_module.scif_fd) {
+    if (mca_btl_scif_module.listening && -1 != mca_btl_scif_module.scif_fd) {
         /* wake up the scif thread */
         scif_epd_t tmpfd;
         tmpfd = scif_open();