Fix double start/stop trace

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

diff --git a/src/bin/lttng-sessiond/ust-app.c b/src/bin/lttng-sessiond/ust-app.c
index 77888048794c39d2cdd329122eccb3af633da39f..335c20ff18556f6df3705be8be6440ff14b1f00e 100644 (file)
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -865,6 +865,8 @@ static struct ust_app_session *create_ust_app_session(
                ret = ustctl_create_session(app->key.sock);
                if (ret < 0) {
                        ERR("Creating session for app pid %d", app->key.pid);
+                       /* This means that the tracer is gone... */
+                       ua_sess = (void*) -1UL;
                        goto error;
                }
 
@@ -1275,6 +1277,13 @@ int ust_app_register(struct ust_register_msg *msg, int sock)
                close(sock);
                return -EINVAL;
        }
+       if (msg->major != LTTNG_UST_COMM_MAJOR) {
+               ERR("Registration failed: application \"%s\" (pid: %d) has "
+                       "communication protocol version %u.%u, but sessiond supports 2.x.\n",
+                       msg->name, msg->pid, msg->major, msg->minor);
+               close(sock);
+               return -EINVAL;
+       }
        lta = zmalloc(sizeof(struct ust_app));
        if (lta == NULL) {
                PERROR("malloc");
@@ -1750,8 +1759,11 @@ int ust_app_create_channel_glb(struct ltt_ust_session *usess,
                 */
                ua_sess = create_ust_app_session(usess, app);
                if (ua_sess == NULL) {
-                       /* Major problem here and it's maybe the tracer or malloc() */
+                       /* The malloc() failed. */
                        goto error;
+               } else if (ua_sess == (void *) -1UL) {
+                       /* The application's socket is not valid. Contiuing */
+                       continue;
                }
 
                /* Create channel onto application */
@@ -2025,10 +2037,12 @@ int ust_app_stop_trace(struct ltt_ust_session *usess, struct ust_app *app)
                goto error_rcu_unlock;
        }
 
-       /* Not started, continuing. */
-       if (ua_sess->started == 0) {
-               goto end;
-       }
+       /*
+        * If started = 0, it means that stop trace has been called for a session
+        * that was never started. This is a code flow error and should never
+        * happen.
+        */
+       assert(ua_sess->started == 1);
 
        /* This inhibits UST tracing */
        ret = ustctl_stop_session(app->key.sock, ua_sess->handle);
@@ -2059,8 +2073,6 @@ int ust_app_stop_trace(struct ltt_ust_session *usess, struct ust_app *app)
                                ret);
        }
 
-       ua_sess->started = 0;
-
 end:
        rcu_read_unlock();
        return 0;