Fix: don't report error if UST app dies

An application dying unexpectedly is a normal behavior so the execution
must continue and not report an error when sending commands onto the
dying application.

Signed-off-by: David Goulet <dgoulet@efficios.com>

diff --git a/src/bin/lttng-sessiond/ust-app.c b/src/bin/lttng-sessiond/ust-app.c
index cf4b7ca772f467712f2f0d1c715ca98e77d8b353..7a34230689c3153b7a9cee0c912eb105d3dd92be 100644 (file)
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -1055,6 +1055,12 @@ int create_ust_channel_context(struct ust_app_channel *ua_chan,
                        ERR("UST app create channel context failed for app (pid: %d) "
                                        "with ret %d", app->pid, ret);
                } else {
+                       /*
+                        * This is normal behavior, an application can die during the
+                        * creation process. Don't report an error so the execution can
+                        * continue normally.
+                        */
+                       ret = 0;
                        DBG3("UST app disable event failed. Application is dead.");
                }
                goto error;
@@ -1093,6 +1099,12 @@ int set_ust_event_filter(struct ust_app_event *ua_event,
                        ERR("UST app event %s filter failed for app (pid: %d) "
                                        "with ret %d", ua_event->attr.name, app->pid, ret);
                } else {
+                       /*
+                        * This is normal behavior, an application can die during the
+                        * creation process. Don't report an error so the execution can
+                        * continue normally.
+                        */
+                       ret = 0;
                        DBG3("UST app filter event failed. Application is dead.");
                }
                goto error;
@@ -1122,6 +1134,12 @@ static int disable_ust_event(struct ust_app *app,
                                        "and session handle %d with ret %d",
                                        ua_event->attr.name, app->pid, ua_sess->handle, ret);
                } else {
+                       /*
+                        * This is normal behavior, an application can die during the
+                        * creation process. Don't report an error so the execution can
+                        * continue normally.
+                        */
+                       ret = 0;
                        DBG3("UST app disable event failed. Application is dead.");
                }
                goto error;
@@ -1152,6 +1170,12 @@ static int disable_ust_channel(struct ust_app *app,
                                        "and session handle %d with ret %d",
                                        ua_chan->name, app->pid, ua_sess->handle, ret);
                } else {
+                       /*
+                        * This is normal behavior, an application can die during the
+                        * creation process. Don't report an error so the execution can
+                        * continue normally.
+                        */
+                       ret = 0;
                        DBG3("UST app disable channel failed. Application is dead.");
                }
                goto error;
@@ -1182,6 +1206,12 @@ static int enable_ust_channel(struct ust_app *app,
                                        "and session handle %d with ret %d",
                                        ua_chan->name, app->pid, ua_sess->handle, ret);
                } else {
+                       /*
+                        * This is normal behavior, an application can die during the
+                        * creation process. Don't report an error so the execution can
+                        * continue normally.
+                        */
+                       ret = 0;
                        DBG3("UST app enable channel failed. Application is dead.");
                }
                goto error;
@@ -1214,6 +1244,12 @@ static int enable_ust_event(struct ust_app *app,
                                        "and session handle %d with ret %d",
                                        ua_event->attr.name, app->pid, ua_sess->handle, ret);
                } else {
+                       /*
+                        * This is normal behavior, an application can die during the
+                        * creation process. Don't report an error so the execution can
+                        * continue normally.
+                        */
+                       ret = 0;
                        DBG3("UST app enable event failed. Application is dead.");
                }
                goto error;
@@ -1294,6 +1330,12 @@ int create_ust_event(struct ust_app *app, struct ust_app_session *ua_sess,
                        ERR("Error ustctl create event %s for app pid: %d with ret %d",
                                        ua_event->attr.name, app->pid, ret);
                } else {
+                       /*
+                        * This is normal behavior, an application can die during the
+                        * creation process. Don't report an error so the execution can
+                        * continue normally.
+                        */
+                       ret = 0;
                        DBG3("UST app create event failed. Application is dead.");
                }
                goto error;
@@ -1732,6 +1774,13 @@ static int create_ust_app_session(struct ltt_ust_session *usess,
                                                app->pid, ret);
                        } else {
                                DBG("UST app creating session failed. Application is dead");
+                               /*
+                                * This is normal behavior, an application can die during the
+                                * creation process. Don't report an error so the execution can
+                                * continue normally. This will get flagged ENOTCONN and the
+                                * caller will handle it.
+                                */
+                               ret = 0;
                        }
                        delete_ust_app_session(-1, ua_sess, app);
                        if (ret != -ENOMEM) {
@@ -3000,6 +3049,12 @@ int ust_app_list_events(struct lttng_event **events)
                                                        app->sock, ret);
                                } else {
                                        DBG3("UST app tp list get failed. Application is dead");
+                                       /*
+                                        * This is normal behavior, an application can die during the
+                                        * creation process. Don't report an error so the execution can
+                                        * continue normally. Continue normal execution.
+                                        */
+                                       break;
                                }
                                goto rcu_error;
                        }
@@ -3094,6 +3149,12 @@ int ust_app_list_event_fields(struct lttng_event_field **fields)
                                                        app->sock, ret);
                                } else {
                                        DBG3("UST app tp list field failed. Application is dead");
+                                       /*
+                                        * This is normal behavior, an application can die during the
+                                        * creation process. Don't report an error so the execution can
+                                        * continue normally.
+                                        */
+                                       break;
                                }
                                goto rcu_error;
                        }
@@ -3709,6 +3770,13 @@ skip_setup:
                                        app->pid, ret);
                } else {
                        DBG("UST app start session failed. Application is dead.");
+                       /*
+                        * This is normal behavior, an application can die during the
+                        * creation process. Don't report an error so the execution can
+                        * continue normally.
+                        */
+                       pthread_mutex_unlock(&ua_sess->lock);
+                       goto end;
                }
                goto error_unlock;
        }
@@ -3784,6 +3852,12 @@ int ust_app_stop_trace(struct ltt_ust_session *usess, struct ust_app *app)
                                        app->pid, ret);
                } else {
                        DBG("UST app stop session failed. Application is dead.");
+                       /*
+                        * This is normal behavior, an application can die during the
+                        * creation process. Don't report an error so the execution can
+                        * continue normally.
+                        */
+                       goto end_unlock;
                }
                goto error_rcu_unlock;
        }
@@ -3807,6 +3881,7 @@ int ust_app_stop_trace(struct ltt_ust_session *usess, struct ust_app *app)
                (void) push_metadata(registry, ua_sess->consumer);
        }
 
+end_unlock:
        pthread_mutex_unlock(&ua_sess->lock);
 end_no_session:
        rcu_read_unlock();
@@ -3861,8 +3936,11 @@ int ust_app_flush_trace(struct ltt_ust_session *usess, struct ust_app *app)
                        } else {
                                DBG3("UST app failed to flush %s. Application is dead.",
                                                ua_chan->name);
-                               /* No need to continue. */
-                               break;
+                               /*
+                                * This is normal behavior, an application can die during the
+                                * creation process. Don't report an error so the execution can
+                                * continue normally.
+                                */
                        }
                        /* Continuing flushing all buffers */
                        continue;