session server BUGFIX do not join ch threads

Made CH threads detached to avoid a deadlock where thread A holds config
wr lock and tries to join thread B, thread B wakes up and tries to lock
config read lock.

Author: Roytak

src/server_config.c

@@ -872,22 +872,18 @@ nc_server_config_ch_del_endpt(struct nc_ch_client *ch_client, struct nc_ch_endpt
 static void
 nc_server_config_destroy_ch_client(struct nc_ch_client *ch_client)
 {
-    pthread_t tid;
     uint16_t i, ch_endpt_count;
 
     /* CH COND LOCK */
     pthread_mutex_lock(&ch_client->thread_data->cond_lock);
     if (ch_client->thread_data->thread_running) {
+        /* notify the thread to exit,
+         * it will stop once the current thread is finished applying the configuration
+         * and releases the config lock */
         ch_client->thread_data->thread_running = 0;
         pthread_cond_signal(&ch_client->thread_data->cond);
         /* CH COND UNLOCK */
         pthread_mutex_unlock(&ch_client->thread_data->cond_lock);
-
-        /* get tid */
-        tid = ch_client->tid;
-
-        /* wait for the thread to terminate */
-        pthread_join(tid, NULL);
     } else {
         /* CH COND UNLOCK */
         pthread_mutex_unlock(&ch_client->thread_data->cond_lock);

src/session_p.h

@@ -557,7 +557,6 @@ struct nc_server_opts {
 
     struct nc_ch_client {
         char *name;                                     /**< Identifier of the Call Home client. */
-        pthread_t tid;                                  /**< Call Home client's thread ID */
         struct nc_ch_client_thread_arg *thread_data;    /**< Data of the Call Home client's thread */
 
         struct nc_ch_endpt {

src/session_server.c

@@ -3249,11 +3249,25 @@ nc_connect_ch_client_dispatch(const char *client_name, nc_server_ch_session_acqu
     pthread_t tid;
     struct nc_ch_client_thread_arg *arg = NULL;
     struct nc_ch_client *ch_client;
+    pthread_attr_t attr;
 
     NC_CHECK_ARG_RET(NULL, client_name, acquire_ctx_cb, release_ctx_cb, new_session_cb, -1);
 
     NC_CHECK_SRV_INIT_RET(-1);
 
+    /* init pthread attribute */
+    if ((r = pthread_attr_init(&attr))) {
+        ERR(NULL, "Initializing pthread attributes failed (%s).", strerror(r));
+        return -1;
+    }
+
+    /* set the thread to be detached */
+    if ((r = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED))) {
+        ERR(NULL, "Setting pthread attributes to detached failed (%s).", strerror(r));
+        rc = -1;
+        goto cleanup;
+    }
+
     /* CONFIG READ LOCK */
     pthread_rwlock_rdlock(&server_opts.config_lock);
 
@@ -3265,7 +3279,8 @@ nc_connect_ch_client_dispatch(const char *client_name, nc_server_ch_session_acqu
 
     if (!ch_client) {
         ERR(NULL, "Client \"%s\" not found.", client_name);
-        return -1;
+        rc = -1;
+        goto cleanup;
     }
 
     /* create the thread argument */
@@ -3283,18 +3298,18 @@ nc_connect_ch_client_dispatch(const char *client_name, nc_server_ch_session_acqu
 
     /* creating the thread */
     arg->thread_running = 1;
-    if ((r = pthread_create(&tid, NULL, nc_ch_client_thread, arg))) {
+    if ((r = pthread_create(&tid, &attr, nc_ch_client_thread, arg))) {
         ERR(NULL, "Creating a new thread failed (%s).", strerror(r));
         rc = -1;
         goto cleanup;
     }
 
     /* the thread now manages arg */
-    ch_client->tid = tid;
     ch_client->thread_data = arg;
     arg = NULL;
 
 cleanup:
+    pthread_attr_destroy(&attr);
     if (arg) {
         free(arg->client_name);
         free(arg);