Ensure sockets are kept open across all their hash table life-span

[lttng-tools.git] / lttng-sessiond / ust-app.c

diff --git a/lttng-sessiond/ust-app.c b/lttng-sessiond/ust-app.c
index 2bee4d90ab7626b7b51c314b67ef539d65441634..46c3dfdc12442247274801d26a3dac72f58bbf95 100644 (file)
--- a/lttng-sessiond/ust-app.c
+++ b/lttng-sessiond/ust-app.c
@@ -143,6 +143,7 @@ static void delete_ust_app(struct ust_app *app)
        struct cds_lfht_node *node;
        struct cds_lfht_iter iter;
        struct ust_app_session *ua_sess;
+       int sock;
 
        rcu_read_lock();
 
@@ -167,9 +168,8 @@ static void delete_ust_app(struct ust_app *app)
        /* Socket is already closed at this point */
 
        /* Delete ust app sessions info */
-       if (app->sock_closed) {
-               app->key.sock = -1;
-       }
+       sock = app->key.sock;
+       app->key.sock = -1;
 
        cds_lfht_for_each_entry(app->sessions, &iter, ua_sess, node) {
                hashtable_del(app->sessions, &iter);
@@ -182,9 +182,13 @@ static void delete_ust_app(struct ust_app *app)
                goto end;
        }
 
-       if (!app->sock_closed) {
-               close(app->key.sock);
-       }
+       /*
+        * Wait until we have removed the key from the sock hash table
+        * before closing this socket, otherwise an application could
+        * re-use the socket ID and race with the teardown, using the
+        * same hash table entry.
+        */
+       close(sock);
 
        DBG2("UST app pid %d deleted", app->key.pid);
        free(app);
@@ -881,10 +885,6 @@ void ust_app_unregister(int sock)
                goto error;
        }
 
-       /* We got called because the socket was closed on the remote end. */
-       close(sock);
-       /* Using a flag because we still need "sock" as a key. */
-       lta->sock_closed = 1;
        hashtable_del(ust_app_ht, &iter);
        call_rcu(&node->head, delete_ust_app_rcu);
 error:
@@ -983,8 +983,6 @@ void ust_app_clean_list(void)
 
        cds_lfht_for_each(ust_app_ht, &iter, node) {
                app = caa_container_of(node, struct ust_app, node);
-               close(app->key.sock);
-               app->sock_closed = 1;
 
                ret = hashtable_del(ust_app_ht, &iter);
                if (!ret) {