Use pipe instead of eventfd() for notification command queue

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

diff --git a/src/bin/lttng-sessiond/notification-thread.c b/src/bin/lttng-sessiond/notification-thread.c
index b580faa2682e1fa7a3a632fc095d93af3ef41b5d..c47b36533e2bdef05ad3ba4c609b9382e10856ed 100644 (file)
--- a/src/bin/lttng-sessiond/notification-thread.c
+++ b/src/bin/lttng-sessiond/notification-thread.c
@@ -54,17 +54,12 @@ void notification_thread_handle_destroy(
                goto end;
        }
 
-       if (handle->cmd_queue.event_fd < 0) {
-               goto end;
-       }
-       ret = close(handle->cmd_queue.event_fd);
-       if (ret < 0) {
-               PERROR("close notification command queue event_fd");
-       }
-
        assert(cds_list_empty(&handle->cmd_queue.list));
        pthread_mutex_destroy(&handle->cmd_queue.lock);
 
+       if (handle->cmd_queue.event_pipe) {
+               lttng_pipe_destroy(handle->cmd_queue.event_pipe);
+       }
        if (handle->channel_monitoring_pipes.ust32_consumer >= 0) {
                ret = close(handle->channel_monitoring_pipes.ust32_consumer);
                if (ret) {
@@ -94,18 +89,22 @@ struct notification_thread_handle *notification_thread_handle_create(
 {
        int ret;
        struct notification_thread_handle *handle;
+       struct lttng_pipe *event_pipe = NULL;
 
        handle = zmalloc(sizeof(*handle));
        if (!handle) {
                goto end;
        }
 
-       /* FIXME Replace eventfd by a pipe to support older kernels. */
-       handle->cmd_queue.event_fd = eventfd(0, EFD_CLOEXEC | EFD_SEMAPHORE);
-       if (handle->cmd_queue.event_fd < 0) {
-               PERROR("eventfd notification command queue");
+       event_pipe = lttng_pipe_open(O_CLOEXEC);
+       if (!event_pipe) {
+               ERR("event_pipe creation");
                goto error;
        }
+
+       handle->cmd_queue.event_pipe = event_pipe;
+       event_pipe = NULL;
+
        CDS_INIT_LIST_HEAD(&handle->cmd_queue.list);
        ret = pthread_mutex_init(&handle->cmd_queue.lock, NULL);
        if (ret) {
@@ -145,6 +144,7 @@ struct notification_thread_handle *notification_thread_handle_create(
 end:
        return handle;
 error:
+       lttng_pipe_destroy(event_pipe);
        notification_thread_handle_destroy(handle);
        return NULL;
 }
@@ -282,7 +282,7 @@ int init_poll_set(struct lttng_poll_event *poll_set,
                ERR("[notification-thread] Failed to add notification channel socket to pollset");
                goto error;
        }
-       ret = lttng_poll_add(poll_set, handle->cmd_queue.event_fd,
+       ret = lttng_poll_add(poll_set, lttng_pipe_get_readfd(handle->cmd_queue.event_pipe),
                        LPOLLIN | LPOLLERR);
        if (ret < 0) {
                ERR("[notification-thread] Failed to add notification command queue event fd to pollset");
@@ -544,7 +544,7 @@ void *thread_notification(void *data)
                                        ERR("[notification-thread] Unexpected poll events %u for notification socket %i", revents, fd);
                                        goto error;
                                }
-                       } else if (fd == handle->cmd_queue.event_fd) {
+                       } else if (fd == lttng_pipe_get_readfd(handle->cmd_queue.event_pipe)) {
                                ret = handle_notification_thread_command(handle,
                                                &state);
                                if (ret < 0) {