+ /* The session was already removed so scheduled for teardown. */
+ continue;
+ }
+
+ if (ua_sess->buffer_type == LTTNG_BUFFER_PER_PID) {
+ (void) ust_app_flush_app_session(lta, ua_sess);
+ }
+
+ /*
+ * Add session to list for teardown. This is safe since at this point we
+ * are the only one using this list.
+ */
+ pthread_mutex_lock(&ua_sess->lock);
+
+ if (ua_sess->deleted) {
+ pthread_mutex_unlock(&ua_sess->lock);
+ continue;
+ }
+
+ /*
+ * Normally, this is done in the delete session process which is
+ * executed in the call rcu below. However, upon registration we can't
+ * afford to wait for the grace period before pushing data or else the
+ * data pending feature can race between the unregistration and stop
+ * command where the data pending command is sent *before* the grace
+ * period ended.
+ *
+ * The close metadata below nullifies the metadata pointer in the
+ * session so the delete session will NOT push/close a second time.
+ */
+ registry = get_session_registry(ua_sess);
+ if (registry) {
+ /* Push metadata for application before freeing the application. */
+ (void) push_metadata(registry, ua_sess->consumer);
+
+ /*
+ * Don't ask to close metadata for global per UID buffers. Close
+ * metadata only on destroy trace session in this case. Also, the
+ * previous push metadata could have flag the metadata registry to
+ * close so don't send a close command if closed.
+ */
+ if (ua_sess->buffer_type != LTTNG_BUFFER_PER_UID) {
+ /* And ask to close it for this session registry. */
+ (void) close_metadata(registry, ua_sess->consumer);
+ }
+ }
+ cds_list_add(&ua_sess->teardown_node, <a->teardown_head);
+
+ pthread_mutex_unlock(&ua_sess->lock);
+ }
+
+ /* Remove application from PID hash table */
+ ret = lttng_ht_del(ust_app_ht_by_sock, &ust_app_sock_iter);
+ assert(!ret);
+
+ /*
+ * Remove application from notify hash table. The thread handling the
+ * notify socket could have deleted the node so ignore on error because
+ * either way it's valid. The close of that socket is handled by the other
+ * thread.
+ */
+ iter.iter.node = <a->notify_sock_n.node;
+ (void) lttng_ht_del(ust_app_ht_by_notify_sock, &iter);
+
+ /*
+ * Ignore return value since the node might have been removed before by an
+ * add replace during app registration because the PID can be reassigned by
+ * the OS.
+ */
+ iter.iter.node = <a->pid_n.node;
+ ret = lttng_ht_del(ust_app_ht, &iter);
+ if (ret) {
+ DBG3("Unregister app by PID %d failed. This can happen on pid reuse",
+ lta->pid);
+ }
+
+ /* Free memory */
+ call_rcu(<a->pid_n.head, delete_ust_app_rcu);
+
+ rcu_read_unlock();
+ return;
+}
+
+/*
+ * Fill events array with all events name of all registered apps.
+ */
+int ust_app_list_events(struct lttng_event **events)
+{
+ int ret, handle;
+ size_t nbmem, count = 0;
+ struct lttng_ht_iter iter;
+ struct ust_app *app;
+ struct lttng_event *tmp_event;
+
+ nbmem = UST_APP_EVENT_LIST_SIZE;
+ tmp_event = zmalloc(nbmem * sizeof(struct lttng_event));
+ if (tmp_event == NULL) {
+ PERROR("zmalloc ust app events");
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ rcu_read_lock();
+
+ cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app, pid_n.node) {
+ struct lttng_ust_tracepoint_iter uiter;
+
+ health_code_update();
+
+ if (!app->compatible) {
+ /*
+ * TODO: In time, we should notice the caller of this error by
+ * telling him that this is a version error.
+ */
+ continue;
+ }
+ pthread_mutex_lock(&app->sock_lock);
+ handle = ustctl_tracepoint_list(app->sock);
+ if (handle < 0) {
+ if (handle != -EPIPE && handle != -LTTNG_UST_ERR_EXITING) {
+ ERR("UST app list events getting handle failed for app pid %d",
+ app->pid);
+ }
+ pthread_mutex_unlock(&app->sock_lock);
+ continue;
+ }
+
+ while ((ret = ustctl_tracepoint_list_get(app->sock, handle,
+ &uiter)) != -LTTNG_UST_ERR_NOENT) {
+ /* Handle ustctl error. */
+ if (ret < 0) {
+ int release_ret;
+
+ if (ret != -LTTNG_UST_ERR_EXITING && ret != -EPIPE) {
+ ERR("UST app tp list get failed for app %d with ret %d",
+ 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;
+ }
+ free(tmp_event);
+ release_ret = ustctl_release_handle(app->sock, handle);
+ if (release_ret < 0 &&
+ release_ret != -LTTNG_UST_ERR_EXITING &&
+ release_ret != -EPIPE) {
+ ERR("Error releasing app handle for app %d with ret %d", app->sock, release_ret);
+ }
+ pthread_mutex_unlock(&app->sock_lock);
+ goto rcu_error;
+ }
+
+ health_code_update();
+ if (count >= nbmem) {
+ /* In case the realloc fails, we free the memory */
+ struct lttng_event *new_tmp_event;
+ size_t new_nbmem;
+
+ new_nbmem = nbmem << 1;
+ DBG2("Reallocating event list from %zu to %zu entries",
+ nbmem, new_nbmem);
+ new_tmp_event = realloc(tmp_event,
+ new_nbmem * sizeof(struct lttng_event));
+ if (new_tmp_event == NULL) {
+ int release_ret;
+
+ PERROR("realloc ust app events");
+ free(tmp_event);
+ ret = -ENOMEM;
+ release_ret = ustctl_release_handle(app->sock, handle);
+ if (release_ret < 0 &&
+ release_ret != -LTTNG_UST_ERR_EXITING &&
+ release_ret != -EPIPE) {
+ ERR("Error releasing app handle for app %d with ret %d", app->sock, release_ret);
+ }
+ pthread_mutex_unlock(&app->sock_lock);
+ goto rcu_error;
+ }
+ /* Zero the new memory */
+ memset(new_tmp_event + nbmem, 0,
+ (new_nbmem - nbmem) * sizeof(struct lttng_event));
+ nbmem = new_nbmem;
+ tmp_event = new_tmp_event;
+ }
+ memcpy(tmp_event[count].name, uiter.name, LTTNG_UST_SYM_NAME_LEN);
+ tmp_event[count].loglevel = uiter.loglevel;
+ tmp_event[count].type = (enum lttng_event_type) LTTNG_UST_TRACEPOINT;
+ tmp_event[count].pid = app->pid;
+ tmp_event[count].enabled = -1;
+ count++;
+ }
+ ret = ustctl_release_handle(app->sock, handle);
+ pthread_mutex_unlock(&app->sock_lock);
+ if (ret < 0 && ret != -LTTNG_UST_ERR_EXITING && ret != -EPIPE) {
+ ERR("Error releasing app handle for app %d with ret %d", app->sock, ret);
+ }
+ }
+
+ ret = count;
+ *events = tmp_event;
+
+ DBG2("UST app list events done (%zu events)", count);
+
+rcu_error:
+ rcu_read_unlock();
+error:
+ health_code_update();
+ return ret;
+}
+
+/*
+ * Fill events array with all events name of all registered apps.
+ */
+int ust_app_list_event_fields(struct lttng_event_field **fields)
+{
+ int ret, handle;
+ size_t nbmem, count = 0;
+ struct lttng_ht_iter iter;
+ struct ust_app *app;
+ struct lttng_event_field *tmp_event;
+
+ nbmem = UST_APP_EVENT_LIST_SIZE;
+ tmp_event = zmalloc(nbmem * sizeof(struct lttng_event_field));
+ if (tmp_event == NULL) {
+ PERROR("zmalloc ust app event fields");
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ rcu_read_lock();
+
+ cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app, pid_n.node) {
+ struct lttng_ust_field_iter uiter;
+
+ health_code_update();
+
+ if (!app->compatible) {
+ /*
+ * TODO: In time, we should notice the caller of this error by
+ * telling him that this is a version error.
+ */
+ continue;
+ }
+ pthread_mutex_lock(&app->sock_lock);
+ handle = ustctl_tracepoint_field_list(app->sock);
+ if (handle < 0) {
+ if (handle != -EPIPE && handle != -LTTNG_UST_ERR_EXITING) {
+ ERR("UST app list field getting handle failed for app pid %d",
+ app->pid);
+ }
+ pthread_mutex_unlock(&app->sock_lock);
+ continue;
+ }
+
+ while ((ret = ustctl_tracepoint_field_list_get(app->sock, handle,
+ &uiter)) != -LTTNG_UST_ERR_NOENT) {
+ /* Handle ustctl error. */
+ if (ret < 0) {
+ int release_ret;
+
+ if (ret != -LTTNG_UST_ERR_EXITING && ret != -EPIPE) {
+ ERR("UST app tp list field failed for app %d with ret %d",
+ 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. Reset list and count for next app.
+ */
+ break;
+ }
+ free(tmp_event);
+ release_ret = ustctl_release_handle(app->sock, handle);
+ pthread_mutex_unlock(&app->sock_lock);
+ if (release_ret < 0 &&
+ release_ret != -LTTNG_UST_ERR_EXITING &&
+ release_ret != -EPIPE) {
+ ERR("Error releasing app handle for app %d with ret %d", app->sock, release_ret);
+ }
+ goto rcu_error;
+ }
+
+ health_code_update();
+ if (count >= nbmem) {
+ /* In case the realloc fails, we free the memory */
+ struct lttng_event_field *new_tmp_event;
+ size_t new_nbmem;
+
+ new_nbmem = nbmem << 1;
+ DBG2("Reallocating event field list from %zu to %zu entries",
+ nbmem, new_nbmem);
+ new_tmp_event = realloc(tmp_event,
+ new_nbmem * sizeof(struct lttng_event_field));
+ if (new_tmp_event == NULL) {
+ int release_ret;
+
+ PERROR("realloc ust app event fields");
+ free(tmp_event);
+ ret = -ENOMEM;
+ release_ret = ustctl_release_handle(app->sock, handle);
+ pthread_mutex_unlock(&app->sock_lock);
+ if (release_ret &&
+ release_ret != -LTTNG_UST_ERR_EXITING &&
+ release_ret != -EPIPE) {
+ ERR("Error releasing app handle for app %d with ret %d", app->sock, release_ret);
+ }
+ goto rcu_error;
+ }
+ /* Zero the new memory */
+ memset(new_tmp_event + nbmem, 0,
+ (new_nbmem - nbmem) * sizeof(struct lttng_event_field));
+ nbmem = new_nbmem;
+ tmp_event = new_tmp_event;
+ }
+
+ memcpy(tmp_event[count].field_name, uiter.field_name, LTTNG_UST_SYM_NAME_LEN);
+ /* Mapping between these enums matches 1 to 1. */
+ tmp_event[count].type = (enum lttng_event_field_type) uiter.type;
+ tmp_event[count].nowrite = uiter.nowrite;
+
+ memcpy(tmp_event[count].event.name, uiter.event_name, LTTNG_UST_SYM_NAME_LEN);
+ tmp_event[count].event.loglevel = uiter.loglevel;
+ tmp_event[count].event.type = LTTNG_EVENT_TRACEPOINT;
+ tmp_event[count].event.pid = app->pid;
+ tmp_event[count].event.enabled = -1;
+ count++;
+ }
+ ret = ustctl_release_handle(app->sock, handle);
+ pthread_mutex_unlock(&app->sock_lock);
+ if (ret < 0 &&
+ ret != -LTTNG_UST_ERR_EXITING &&
+ ret != -EPIPE) {
+ ERR("Error releasing app handle for app %d with ret %d", app->sock, ret);
+ }
+ }
+
+ ret = count;
+ *fields = tmp_event;
+
+ DBG2("UST app list event fields done (%zu events)", count);
+
+rcu_error:
+ rcu_read_unlock();
+error:
+ health_code_update();
+ return ret;
+}
+
+/*
+ * Free and clean all traceable apps of the global list.
+ *
+ * Should _NOT_ be called with RCU read-side lock held.
+ */
+void ust_app_clean_list(void)
+{
+ int ret;
+ struct ust_app *app;
+ struct lttng_ht_iter iter;
+
+ DBG2("UST app cleaning registered apps hash table");
+
+ rcu_read_lock();
+
+ if (ust_app_ht) {
+ cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app, pid_n.node) {
+ ret = lttng_ht_del(ust_app_ht, &iter);
+ assert(!ret);
+ call_rcu(&app->pid_n.head, delete_ust_app_rcu);
+ }
+ }
+
+ /* Cleanup socket hash table */
+ if (ust_app_ht_by_sock) {
+ cds_lfht_for_each_entry(ust_app_ht_by_sock->ht, &iter.iter, app,
+ sock_n.node) {
+ ret = lttng_ht_del(ust_app_ht_by_sock, &iter);
+ assert(!ret);
+ }
+ }
+
+ /* Cleanup notify socket hash table */
+ if (ust_app_ht_by_notify_sock) {
+ cds_lfht_for_each_entry(ust_app_ht_by_notify_sock->ht, &iter.iter, app,
+ notify_sock_n.node) {
+ ret = lttng_ht_del(ust_app_ht_by_notify_sock, &iter);
+ assert(!ret);
+ }
+ }
+ rcu_read_unlock();
+
+ /* Destroy is done only when the ht is empty */
+ if (ust_app_ht) {
+ ht_cleanup_push(ust_app_ht);
+ }
+ if (ust_app_ht_by_sock) {
+ ht_cleanup_push(ust_app_ht_by_sock);
+ }
+ if (ust_app_ht_by_notify_sock) {
+ ht_cleanup_push(ust_app_ht_by_notify_sock);
+ }
+}
+
+/*
+ * Init UST app hash table.
+ */
+int ust_app_ht_alloc(void)
+{
+ ust_app_ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
+ if (!ust_app_ht) {
+ return -1;
+ }
+ ust_app_ht_by_sock = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
+ if (!ust_app_ht_by_sock) {
+ return -1;
+ }
+ ust_app_ht_by_notify_sock = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
+ if (!ust_app_ht_by_notify_sock) {
+ return -1;
+ }
+ return 0;
+}
+
+/*
+ * For a specific UST session, disable the channel for all registered apps.
+ */
+int ust_app_disable_channel_glb(struct ltt_ust_session *usess,
+ struct ltt_ust_channel *uchan)
+{
+ int ret = 0;
+ struct lttng_ht_iter iter;
+ struct lttng_ht_node_str *ua_chan_node;
+ struct ust_app *app;
+ struct ust_app_session *ua_sess;
+ struct ust_app_channel *ua_chan;
+
+ if (usess == NULL || uchan == NULL) {
+ ERR("Disabling UST global channel with NULL values");
+ ret = -1;
+ goto error;
+ }
+
+ DBG2("UST app disabling channel %s from global domain for session id %" PRIu64,
+ uchan->name, usess->id);
+
+ rcu_read_lock();
+
+ /* For every registered applications */
+ cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app, pid_n.node) {
+ struct lttng_ht_iter uiter;
+ if (!app->compatible) {
+ /*
+ * TODO: In time, we should notice the caller of this error by
+ * telling him that this is a version error.
+ */
+ continue;
+ }
+ ua_sess = lookup_session_by_app(usess, app);
+ if (ua_sess == NULL) {
+ continue;
+ }
+
+ /* Get channel */
+ lttng_ht_lookup(ua_sess->channels, (void *)uchan->name, &uiter);
+ ua_chan_node = lttng_ht_iter_get_node_str(&uiter);
+ /* If the session if found for the app, the channel must be there */
+ assert(ua_chan_node);
+
+ ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
+ /* The channel must not be already disabled */
+ assert(ua_chan->enabled == 1);
+
+ /* Disable channel onto application */
+ ret = disable_ust_app_channel(ua_sess, ua_chan, app);
+ if (ret < 0) {
+ /* XXX: We might want to report this error at some point... */
+ continue;
+ }
+ }
+
+ rcu_read_unlock();
+
+error:
+ return ret;
+}
+
+/*
+ * For a specific UST session, enable the channel for all registered apps.
+ */
+int ust_app_enable_channel_glb(struct ltt_ust_session *usess,
+ struct ltt_ust_channel *uchan)
+{
+ int ret = 0;
+ struct lttng_ht_iter iter;
+ struct ust_app *app;
+ struct ust_app_session *ua_sess;
+
+ if (usess == NULL || uchan == NULL) {
+ ERR("Adding UST global channel to NULL values");
+ ret = -1;
+ goto error;
+ }
+
+ DBG2("UST app enabling channel %s to global domain for session id %" PRIu64,
+ uchan->name, usess->id);
+
+ rcu_read_lock();
+
+ /* For every registered applications */
+ cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app, pid_n.node) {
+ if (!app->compatible) {
+ /*
+ * TODO: In time, we should notice the caller of this error by
+ * telling him that this is a version error.
+ */
+ continue;
+ }
+ ua_sess = lookup_session_by_app(usess, app);
+ if (ua_sess == NULL) {
+ continue;
+ }
+
+ /* Enable channel onto application */
+ ret = enable_ust_app_channel(ua_sess, uchan, app);
+ if (ret < 0) {
+ /* XXX: We might want to report this error at some point... */
+ continue;
+ }
+ }
+
+ rcu_read_unlock();
+
+error:
+ return ret;
+}
+
+/*
+ * Disable an event in a channel and for a specific session.
+ */
+int ust_app_disable_event_glb(struct ltt_ust_session *usess,
+ struct ltt_ust_channel *uchan, struct ltt_ust_event *uevent)
+{
+ int ret = 0;
+ struct lttng_ht_iter iter, uiter;
+ struct lttng_ht_node_str *ua_chan_node;
+ struct ust_app *app;
+ struct ust_app_session *ua_sess;
+ struct ust_app_channel *ua_chan;
+ struct ust_app_event *ua_event;
+
+ DBG("UST app disabling event %s for all apps in channel "
+ "%s for session id %" PRIu64,
+ uevent->attr.name, uchan->name, usess->id);
+
+ rcu_read_lock();
+
+ /* For all registered applications */
+ cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app, pid_n.node) {
+ if (!app->compatible) {
+ /*
+ * TODO: In time, we should notice the caller of this error by
+ * telling him that this is a version error.
+ */
+ continue;
+ }
+ ua_sess = lookup_session_by_app(usess, app);
+ if (ua_sess == NULL) {
+ /* Next app */
+ continue;
+ }
+
+ /* Lookup channel in the ust app session */
+ lttng_ht_lookup(ua_sess->channels, (void *)uchan->name, &uiter);
+ ua_chan_node = lttng_ht_iter_get_node_str(&uiter);
+ if (ua_chan_node == NULL) {
+ DBG2("Channel %s not found in session id %" PRIu64 " for app pid %d."
+ "Skipping", uchan->name, usess->id, app->pid);
+ continue;
+ }
+ ua_chan = caa_container_of(ua_chan_node, struct ust_app_channel, node);
+
+ ua_event = find_ust_app_event(ua_chan->events, uevent->attr.name,
+ uevent->filter, uevent->attr.loglevel,
+ uevent->exclusion);
+ if (ua_event == NULL) {
+ DBG2("Event %s not found in channel %s for app pid %d."
+ "Skipping", uevent->attr.name, uchan->name, app->pid);
+ continue;
+ }
+
+ ret = disable_ust_app_event(ua_sess, ua_event, app);
+ if (ret < 0) {
+ /* XXX: Report error someday... */
+ continue;
+ }
+ }
+
+ rcu_read_unlock();
+
+ return ret;
+}
+
+/*
+ * For a specific UST session, create the channel for all registered apps.
+ */
+int ust_app_create_channel_glb(struct ltt_ust_session *usess,
+ struct ltt_ust_channel *uchan)
+{
+ int ret = 0, created;
+ struct lttng_ht_iter iter;
+ struct ust_app *app;
+ struct ust_app_session *ua_sess = NULL;
+
+ /* Very wrong code flow */
+ assert(usess);
+ assert(uchan);
+
+ DBG2("UST app adding channel %s to UST domain for session id %" PRIu64,
+ uchan->name, usess->id);
+
+ rcu_read_lock();
+
+ /* For every registered applications */
+ cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app, pid_n.node) {
+ if (!app->compatible) {
+ /*
+ * TODO: In time, we should notice the caller of this error by
+ * telling him that this is a version error.
+ */
+ continue;
+ }
+ if (!trace_ust_pid_tracker_lookup(usess, app->pid)) {
+ /* Skip. */
+ continue;
+ }
+
+ /*
+ * Create session on the tracer side and add it to app session HT. Note
+ * that if session exist, it will simply return a pointer to the ust
+ * app session.
+ */
+ ret = create_ust_app_session(usess, app, &ua_sess, &created);
+ if (ret < 0) {
+ switch (ret) {
+ case -ENOTCONN:
+ /*
+ * The application's socket is not valid. Either a bad socket
+ * or a timeout on it. We can't inform the caller that for a
+ * specific app, the session failed so lets continue here.
+ */
+ ret = 0; /* Not an error. */
+ continue;
+ case -ENOMEM:
+ default:
+ goto error_rcu_unlock;
+ }
+ }
+ assert(ua_sess);
+
+ pthread_mutex_lock(&ua_sess->lock);
+
+ if (ua_sess->deleted) {
+ pthread_mutex_unlock(&ua_sess->lock);
+ continue;
+ }
+
+ if (!strncmp(uchan->name, DEFAULT_METADATA_NAME,
+ sizeof(uchan->name))) {
+ copy_channel_attr_to_ustctl(&ua_sess->metadata_attr, &uchan->attr);
+ ret = 0;
+ } else {
+ /* Create channel onto application. We don't need the chan ref. */
+ ret = create_ust_app_channel(ua_sess, uchan, app,
+ LTTNG_UST_CHAN_PER_CPU, usess, NULL);
+ }
+ pthread_mutex_unlock(&ua_sess->lock);
+ if (ret < 0) {
+ /* Cleanup the created session if it's the case. */
+ if (created) {
+ destroy_app_session(app, ua_sess);
+ }
+ switch (ret) {
+ case -ENOTCONN:
+ /*
+ * The application's socket is not valid. Either a bad socket
+ * or a timeout on it. We can't inform the caller that for a
+ * specific app, the session failed so lets continue here.
+ */
+ ret = 0; /* Not an error. */
+ continue;
+ case -ENOMEM:
+ default:
+ goto error_rcu_unlock;
+ }
+ }
+ }
+
+error_rcu_unlock:
+ rcu_read_unlock();
+ return ret;
+}
+
+/*
+ * Enable event for a specific session and channel on the tracer.
+ */
+int ust_app_enable_event_glb(struct ltt_ust_session *usess,
+ struct ltt_ust_channel *uchan, struct ltt_ust_event *uevent)
+{
+ int ret = 0;
+ struct lttng_ht_iter iter, uiter;
+ struct lttng_ht_node_str *ua_chan_node;
+ struct ust_app *app;
+ struct ust_app_session *ua_sess;
+ struct ust_app_channel *ua_chan;
+ struct ust_app_event *ua_event;
+
+ DBG("UST app enabling event %s for all apps for session id %" PRIu64,
+ uevent->attr.name, usess->id);
+
+ /*
+ * NOTE: At this point, this function is called only if the session and
+ * channel passed are already created for all apps. and enabled on the
+ * tracer also.
+ */
+
+ rcu_read_lock();
+
+ /* For all registered applications */
+ cds_lfht_for_each_entry(ust_app_ht->ht, &iter.iter, app, pid_n.node) {
+ if (!app->compatible) {
+ /*
+ * TODO: In time, we should notice the caller of this error by
+ * telling him that this is a version error.
+ */
+ continue;