Use pipe instead of eventfd() for notification command queue

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/bin/lttng-sessiond/notification-thread-commands.c b/src/bin/lttng-sessiond/notification-thread-commands.c
index d9fdf01588465a3e826bbc53b3a0e6cb35d29705..cca667476b2efffd32ac520ba1e764198a538328 100644 (file)
--- a/src/bin/lttng-sessiond/notification-thread-commands.c
+++ b/src/bin/lttng-sessiond/notification-thread-commands.c
@@ -44,7 +44,7 @@ int run_command_wait(struct notification_thread_handle *handle,
        cds_list_add_tail(&cmd->cmd_list_node,
                        &handle->cmd_queue.list);
        /* Wake-up thread. */
-       ret = write(handle->cmd_queue.event_fd,
+       ret = write(lttng_pipe_get_writefd(handle->cmd_queue.event_pipe),
                        &notification_counter, sizeof(notification_counter));
        if (ret < 0) {
                PERROR("write to notification thread's queue event fd");

diff --git a/src/bin/lttng-sessiond/notification-thread-events.c b/src/bin/lttng-sessiond/notification-thread-events.c
index bfdbb2085e5e36366ae505ec59a71dde7adcdde6..327ea7fc34907119cde2662bb42ee34262179f5c 100644 (file)
--- a/src/bin/lttng-sessiond/notification-thread-events.c
+++ b/src/bin/lttng-sessiond/notification-thread-events.c
@@ -1275,7 +1275,7 @@ int handle_notification_thread_command(
        struct notification_thread_command *cmd;
 
        /* Read event_fd to put it back into a quiescent state. */
-       ret = read(handle->cmd_queue.event_fd, &counter, sizeof(counter));
+       ret = read(lttng_pipe_get_readfd(handle->cmd_queue.event_pipe), &counter, sizeof(counter));
        if (ret == -1) {
                goto error;
        }

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) {

diff --git a/src/bin/lttng-sessiond/notification-thread.h b/src/bin/lttng-sessiond/notification-thread.h
index a9c771104d48118a1a61ce65008f8df9b76c3439..2aa76e71ca422bfd007dfcaec4786ebb1d7db549 100644 (file)
--- a/src/bin/lttng-sessiond/notification-thread.h
+++ b/src/bin/lttng-sessiond/notification-thread.h
@@ -30,11 +30,11 @@
 struct notification_thread_handle {
        /*
         * Queue of struct notification command.
-        * event_fd must be WRITE(2) to signal that a new command
+        * event_pipe must be WRITE(2) to signal that a new command
         * has been enqueued.
         */
        struct {
-               int event_fd;
+               struct lttng_pipe *event_pipe;
                struct cds_list_head list;
                pthread_mutex_t lock;
        } cmd_queue;