Fix: Initialize global agent_apps_ht_by_sock on session daemon launch

[lttng-tools.git] / src / bin / lttng-sessiond / agent.c

diff --git a/src/bin/lttng-sessiond/agent.c b/src/bin/lttng-sessiond/agent.c
index 6375894a7d7dfd45add0b4fc742daa83c2993cd9..7349d09f0e7edd9dbfad5e082e89a0825f440a26 100644 (file)
--- a/src/bin/lttng-sessiond/agent.c
+++ b/src/bin/lttng-sessiond/agent.c
@@ -680,6 +680,8 @@ void agent_add_app(struct agent_app *app)
 
 /*
  * Delete agent application from the global hash table.
+ *
+ * rcu_read_lock() must be held by the caller.
  */
 void agent_delete_app(struct agent_app *app)
 {
@@ -691,14 +693,12 @@ void agent_delete_app(struct agent_app *app)
        DBG3("Agent deleting app pid: %d and sock: %d", app->pid, app->sock->fd);
 
        iter.iter.node = &app->node.node;
-       rcu_read_lock();
        ret = lttng_ht_del(agent_apps_ht_by_sock, &iter);
-       rcu_read_unlock();
        assert(!ret);
 }
 
 /*
- * Destroy a agent application object by detaching it from its corresponding
+ * Destroy an agent application object by detaching it from its corresponding
  * UST app if one is connected by closing the socket. Finally, perform a
  * delayed memory reclaim.
  */
@@ -961,16 +961,67 @@ void agent_destroy(struct agent *agt)
 }
 
 /*
- * Initialize agent subsystem.
+ * Allocate agent_apps_ht_by_sock.
  */
-int agent_setup(void)
+int agent_app_ht_alloc(void)
 {
+       int ret = 0;
+
        agent_apps_ht_by_sock = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
        if (!agent_apps_ht_by_sock) {
-               return -1;
+               ret = -1;
        }
 
-       return 0;
+       return ret;
+}
+
+/*
+ * Destroy a agent application by socket.
+ */
+void agent_destroy_app_by_sock(int sock)
+{
+       struct agent_app *app;
+
+       assert(sock >= 0);
+
+       /*
+        * Not finding an application is a very important error that should NEVER
+        * happen. The hash table deletion is ONLY done through this call when the
+        * main sessiond thread is torn down.
+        */
+       rcu_read_lock();
+       app = agent_find_app_by_sock(sock);
+       assert(app);
+
+       /* RCU read side lock is assumed to be held by this function. */
+       agent_delete_app(app);
+
+       /* The application is freed in a RCU call but the socket is closed here. */
+       agent_destroy_app(app);
+       rcu_read_unlock();
+}
+
+/*
+ * Clean-up the agent app hash table and destroy it.
+ */
+void agent_app_ht_clean(void)
+{
+       struct lttng_ht_node_ulong *node;
+       struct lttng_ht_iter iter;
+
+       if (!agent_apps_ht_by_sock) {
+               return;
+       }
+       rcu_read_lock();
+       cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, node, node) {
+               struct agent_app *app;
+
+               app = caa_container_of(node, struct agent_app, node);
+               agent_destroy_app_by_sock(app->sock->fd);
+       }
+       rcu_read_unlock();
+
+       lttng_ht_destroy(agent_apps_ht_by_sock);
 }
 
 /*