From 8ada111f6d3ab40d1c33cf1a7b2546de9a47d1d5 Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Wed, 17 May 2017 16:03:13 -0400
Subject: [PATCH 1/1] Fix: use lttng_waiter instead of futex in notification
 thread
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 .../lttng-sessiond/notification-thread-commands.c    |  6 ++----
 .../lttng-sessiond/notification-thread-commands.h    |  5 +++--
 src/bin/lttng-sessiond/notification-thread-events.c  |  4 ++--
 src/bin/lttng-sessiond/notification-thread.c         | 12 +-----------
 4 files changed, 8 insertions(+), 19 deletions(-)

diff --git a/src/bin/lttng-sessiond/notification-thread-commands.c b/src/bin/lttng-sessiond/notification-thread-commands.c
index 5483a317f..d9fdf0158 100644
--- a/src/bin/lttng-sessiond/notification-thread-commands.c
+++ b/src/bin/lttng-sessiond/notification-thread-commands.c
@@ -20,7 +20,6 @@
 #include "notification-thread.h"
 #include "notification-thread-commands.h"
 #include <common/error.h>
-#include <common/futex.h>
 #include <unistd.h>
 #include <stdint.h>
 #include <inttypes.h>
@@ -30,6 +29,7 @@ void init_notification_thread_command(struct notification_thread_command *cmd)
 {
 	memset(cmd, 0, sizeof(*cmd));
 	CDS_INIT_LIST_HEAD(&cmd->cmd_list_node);
+	lttng_waiter_init(&cmd->reply_waiter);
 }
 
 static
@@ -39,8 +39,6 @@ int run_command_wait(struct notification_thread_handle *handle,
 	int ret;
 	uint64_t notification_counter = 1;
 
-	futex_nto1_prepare(&cmd->reply_futex);
-
 	pthread_mutex_lock(&handle->cmd_queue.lock);
 	/* Add to queue. */
 	cds_list_add_tail(&cmd->cmd_list_node,
@@ -59,7 +57,7 @@ int run_command_wait(struct notification_thread_handle *handle,
 	}
 	pthread_mutex_unlock(&handle->cmd_queue.lock);
 
-	futex_nto1_wait(&cmd->reply_futex);
+	lttng_waiter_wait(&cmd->reply_waiter);
 	return 0;
 error_unlock_queue:
 	pthread_mutex_unlock(&handle->cmd_queue.lock);
diff --git a/src/bin/lttng-sessiond/notification-thread-commands.h b/src/bin/lttng-sessiond/notification-thread-commands.h
index fc7e90bcb..8885d4faf 100644
--- a/src/bin/lttng-sessiond/notification-thread-commands.h
+++ b/src/bin/lttng-sessiond/notification-thread-commands.h
@@ -22,6 +22,7 @@
 #include <lttng/lttng-error.h>
 #include <urcu/rculfhash.h>
 #include "notification-thread.h"
+#include <common/waiter.h>
 
 struct notification_thread_data;
 struct lttng_trigger;
@@ -65,8 +66,8 @@ struct notification_thread_command {
 		} remove_channel;
 	} parameters;
 
-	/* Futex on which to wait for command reply (optional). */
-	int32_t reply_futex;
+	/* lttng_waiter on which to wait for command reply (optional). */
+	struct lttng_waiter reply_waiter;
 	enum lttng_error_code reply_code;
 };
 
diff --git a/src/bin/lttng-sessiond/notification-thread-events.c b/src/bin/lttng-sessiond/notification-thread-events.c
index 8e70baed5..b0657a4c5 100644
--- a/src/bin/lttng-sessiond/notification-thread-events.c
+++ b/src/bin/lttng-sessiond/notification-thread-events.c
@@ -1110,12 +1110,12 @@ int handle_notification_thread_command(
 	}
 end:
 	cds_list_del(&cmd->cmd_list_node);
-	futex_nto1_wake(&cmd->reply_futex);
+	lttng_waiter_wake_up(&cmd->reply_waiter);
 	pthread_mutex_unlock(&handle->cmd_queue.lock);
 	return ret;
 error_unlock:
 	/* Wake-up and return a fatal error to the calling thread. */
-	futex_nto1_wake(&cmd->reply_futex);
+	lttng_waiter_wake_up(&cmd->reply_waiter);
 	pthread_mutex_unlock(&handle->cmd_queue.lock);
 	cmd->reply_code = LTTNG_ERR_FATAL;
 error:
diff --git a/src/bin/lttng-sessiond/notification-thread.c b/src/bin/lttng-sessiond/notification-thread.c
index 059e62059..e0937d8e5 100644
--- a/src/bin/lttng-sessiond/notification-thread.c
+++ b/src/bin/lttng-sessiond/notification-thread.c
@@ -25,7 +25,6 @@
 #include <common/config/session-config.h>
 #include <common/defaults.h>
 #include <common/utils.h>
-#include <common/futex.h>
 #include <common/align.h>
 #include <common/time.h>
 #include <sys/eventfd.h>
@@ -158,7 +157,6 @@ void notification_thread_handle_destroy(
 		struct notification_thread_handle *handle)
 {
 	int ret;
-	struct notification_thread_command *cmd, *tmp;
 
 	if (!handle) {
 		goto end;
@@ -172,15 +170,7 @@ void notification_thread_handle_destroy(
 		PERROR("close notification command queue event_fd");
 	}
 
-	pthread_mutex_lock(&handle->cmd_queue.lock);
-	/* Purge queue of in-flight commands and mark them as cancelled. */
-	cds_list_for_each_entry_safe(cmd, tmp, &handle->cmd_queue.list,
-			cmd_list_node) {
-		cds_list_del(&cmd->cmd_list_node);
-		cmd->reply_code = LTTNG_ERR_COMMAND_CANCELLED;
-		futex_nto1_wake(&cmd->reply_futex);
-	}
-	pthread_mutex_unlock(&handle->cmd_queue.lock);
+	assert(cds_list_empty(&handle->cmd_queue.list));
 	pthread_mutex_destroy(&handle->cmd_queue.lock);
 
 	if (handle->channel_monitoring_pipes.ust32_consumer >= 0) {
-- 
2.34.1