fix thread name on fatal and cgroup netdev rename crash (#16771)

* fix thread name on fatal

* fix cgroup missing reference counter dup

2 files changed, 20 insertions, 10 deletions

diff --git a/collectors/cgroups.plugin/cgroup-top.c b/collectors/cgroups.plugin/cgroup-top.c
index aa158a0102..de794d8811 100644
--- a/collectors/cgroups.plugin/cgroup-top.c
+++ b/collectors/cgroups.plugin/cgroup-top.c
@@ -15,17 +15,17 @@ void cgroup_netdev_link_init(void) {
 }
 
 const DICTIONARY_ITEM *cgroup_netdev_get(struct cgroup *cg) {
-    if(cg->cgroup_netdev_link)
-        return cg->cgroup_netdev_link;
-
-
-    struct cgroup_netdev_link t = {
+    if(!cg->cgroup_netdev_link) {
+        struct cgroup_netdev_link t = {
             .read_slot = 0,
-            .received = { NAN, NAN },
-            .sent = { NAN, NAN },
-    };
+            .received = {NAN, NAN},
+            .sent = {NAN, NAN},
+        };
+
+        cg->cgroup_netdev_link =
+            dictionary_set_and_acquire_item(cgroup_netdev_link_dict, cg->id, &t, sizeof(struct cgroup_netdev_link));
+    }
 
-    cg->cgroup_netdev_link = dictionary_set_and_acquire_item(cgroup_netdev_link_dict, cg->id, &t, sizeof(struct cgroup_netdev_link));
     return dictionary_acquired_item_dup(cgroup_netdev_link_dict, cg->cgroup_netdev_link);
 }
 
@@ -34,6 +34,7 @@ void cgroup_netdev_delete(struct cgroup *cg) {
         dictionary_acquired_item_release(cgroup_netdev_link_dict, cg->cgroup_netdev_link);
         dictionary_del(cgroup_netdev_link_dict, cg->id);
         dictionary_garbage_collect(cgroup_netdev_link_dict);
+        cg->cgroup_netdev_link = NULL;
     }
 }
 
diff --git a/libnetdata/log/log.c b/libnetdata/log/log.c
index b93ef2cc29..abc1207824 100644
--- a/libnetdata/log/log.c
+++ b/libnetdata/log/log.c
@@ -2305,7 +2305,16 @@ void netdata_logger_fatal( const char *file, const char *function, const unsigne
     char action_data[70+1];
     snprintfz(action_data, 70, "%04lu@%-10.10s:%-15.15s/%d", line, file, function, saved_errno);
 
-    const char *thread_tag = thread_log_fields[NDF_THREAD_TAG].entry.txt;
+    char os_threadname[NETDATA_THREAD_NAME_MAX + 1];
+    const char *thread_tag = netdata_thread_tag();
+    if(!netdata_thread_tag_exists()) {
+        if (!netdata_thread_tag_exists()) {
+            os_thread_get_current_name_np(os_threadname);
+            if ('\0' != os_threadname[0])
+                /* If it is not an empty string replace "MAIN" thread_tag */
+                thread_tag = os_threadname;
+        }
+    }
     if(!thread_tag)
         thread_tag = "UNKNOWN";