X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fagent-thread.c;h=9c98d30ab4e71accd303a442d41b45feeee212b6;hp=2439b3e28ec0fe73c54c08be3d32b3c7c70af005;hb=5b0936814a6004448eeec430b2dfea534f35a2fc;hpb=427392b43cfe21d440808494f87564fc0224dd70

diff --git a/src/bin/lttng-sessiond/agent-thread.c b/src/bin/lttng-sessiond/agent-thread.c
index 2439b3e28..9c98d30ab 100644
--- a/src/bin/lttng-sessiond/agent-thread.c
+++ b/src/bin/lttng-sessiond/agent-thread.c
@@ -31,6 +31,9 @@
 #include "lttng-sessiond.h"
 #include "session.h"
 #include "utils.h"
+#include "thread.h"
+
+static int agent_tracing_enabled = -1;
 
 /*
  * Note that there is not port here. It's set after this URI is parsed so we
@@ -57,6 +60,10 @@ static void update_agent_app(struct agent_app *app)
 
 	session_lock_list();
 	cds_list_for_each_entry_safe(session, stmp, &list->head, list) {
+		if (!session_get(session)) {
+			continue;
+		}
+
 		session_lock(session);
 		if (session->ust_session) {
 			struct agent *agt;
@@ -69,6 +76,7 @@ static void update_agent_app(struct agent_app *app)
 			rcu_read_unlock();
 		}
 		session_unlock(session);
+		session_put(session);
 	}
 	session_unlock_list();
 }
@@ -81,6 +89,8 @@ static struct lttcomm_sock *init_tcp_socket(void)
 	int ret;
 	struct lttng_uri *uri = NULL;
 	struct lttcomm_sock *sock = NULL;
+	unsigned int port;
+	bool bind_succeeded = false;
 
 	/*
 	 * This should never fail since the URI is hardcoded and the port is set
@@ -88,8 +98,8 @@ static struct lttcomm_sock *init_tcp_socket(void)
 	 */
 	ret = uri_parse(default_reg_uri, &uri);
 	assert(ret);
-	assert(agent_tcp_port);
-	uri->port = agent_tcp_port;
+	assert(config.agent_tcp_port.begin > 0);
+	uri->port = config.agent_tcp_port.begin;
 
 	sock = lttcomm_alloc_sock_from_uri(uri);
 	uri_free(uri);
@@ -103,11 +113,43 @@ static struct lttcomm_sock *init_tcp_socket(void)
 		goto error;
 	}
 
-	ret = sock->ops->bind(sock);
-	if (ret < 0) {
-		WARN("Another session daemon is using this agent port. Agent support "
-				"will be deactivated to prevent interfering with the tracing.");
-		goto error;
+	for (port = config.agent_tcp_port.begin;
+			port <= config.agent_tcp_port.end; port++) {
+		ret = lttcomm_sock_set_port(sock, (uint16_t) port);
+		if (ret) {
+			ERR("[agent-thread] Failed to set port %u on socket",
+					port);
+			goto error;
+		}
+		DBG3("[agent-thread] Trying to bind on port %u", port);
+		ret = sock->ops->bind(sock);
+		if (!ret) {
+			bind_succeeded = true;
+			break;
+		}
+
+		if (errno == EADDRINUSE) {
+			DBG("Failed to bind to port %u since it is already in use",
+					port);
+		} else {
+			PERROR("Failed to bind to port %u", port);
+			goto error;
+		}
+	}
+
+	if (!bind_succeeded) {
+		if (config.agent_tcp_port.begin == config.agent_tcp_port.end) {
+			WARN("Another process is already using the agent port %i. "
+					"Agent support will be deactivated.",
+					config.agent_tcp_port.begin);
+			goto error;
+		} else {
+			WARN("All ports in the range [%i, %i] are already in use. "
+					"Agent support will be deactivated.",
+					config.agent_tcp_port.begin,
+					config.agent_tcp_port.end);
+			goto error;
+		}
 	}
 
 	ret = sock->ops->listen(sock, -1);
@@ -116,7 +158,7 @@ static struct lttcomm_sock *init_tcp_socket(void)
 	}
 
 	DBG("[agent-thread] Listening on TCP port %u and socket %d",
-			agent_tcp_port, sock->fd);
+			port, sock->fd);
 
 	return sock;
 
@@ -132,9 +174,19 @@ error:
  */
 static void destroy_tcp_socket(struct lttcomm_sock *sock)
 {
+	int ret;
+	uint16_t port;
+
 	assert(sock);
 
-	DBG3("[agent-thread] Destroy TCP socket on port %u", agent_tcp_port);
+	ret = lttcomm_sock_get_port(sock, &port);
+	if (ret) {
+		ERR("[agent-thread] Failed to get port of agent TCP socket");
+		port = 0;
+	}
+
+	DBG3("[agent-thread] Destroy TCP socket on port %" PRIu16,
+			port);
 
 	/* This will return gracefully if fd is invalid. */
 	sock->ops->close(sock);
@@ -223,15 +275,35 @@ error:
 	return ret;
 }
 
+bool agent_tracing_is_enabled(void)
+{
+	int enabled;
+
+	enabled = uatomic_read(&agent_tracing_enabled);
+	assert(enabled != -1);
+	return enabled == 1;
+}
+
+/*
+ * Write agent TCP port using the rundir.
+ */
+static int write_agent_port(uint16_t port)
+{
+	return utils_create_pid_file((pid_t) port,
+			config.agent_port_file_path.value);
+}
+
 /*
  * This thread manage application notify communication.
  */
-void *agent_thread_manage_registration(void *data)
+static void *thread_agent_management(void *data)
 {
 	int i, ret, pollfd;
 	uint32_t revents, nb_fd;
 	struct lttng_poll_event events;
 	struct lttcomm_sock *reg_sock;
+	struct lttng_pipe *quit_pipe = data;
+	const int quit_pipe_read_fd = lttng_pipe_get_readfd(quit_pipe);
 
 	DBG("[agent-thread] Manage agent application registration.");
 
@@ -241,17 +313,44 @@ void *agent_thread_manage_registration(void *data)
 	/* Agent initialization call MUST be called before starting the thread. */
 	assert(agent_apps_ht_by_sock);
 
-	/* Create pollset with size 2, quit pipe and socket. */
-	ret = sessiond_set_thread_pollset(&events, 2);
+	/* Create pollset with size 2, quit pipe and registration socket. */
+	ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
 	if (ret < 0) {
 		goto error_poll_create;
 	}
 
+	ret = lttng_poll_add(&events, quit_pipe_read_fd,
+			LPOLLIN | LPOLLERR);
+	if (ret < 0) {
+		goto error_tcp_socket;
+	}
+
 	reg_sock = init_tcp_socket();
-	if (!reg_sock) {
+	if (reg_sock) {
+		uint16_t port;
+
+		assert(lttcomm_sock_get_port(reg_sock, &port) == 0);
+
+		ret = write_agent_port(port);
+		if (ret) {
+			ERR("[agent-thread] Failed to create agent port file: agent tracing will be unavailable");
+			/* Don't prevent the launch of the sessiond on error. */
+			sessiond_notify_ready();
+			goto error;
+		}
+	} else {
+		/* Don't prevent the launch of the sessiond on error. */
+		sessiond_notify_ready();
 		goto error_tcp_socket;
 	}
 
+	/*
+	 * Signal that the agent thread is ready. The command thread
+	 * may start to query whether or not agent tracing is enabled.
+	 */
+	uatomic_set(&agent_tracing_enabled, 1);
+	sessiond_notify_ready();
+
 	/* Add TCP socket to poll set. */
 	ret = lttng_poll_add(&events, reg_sock->fd,
 			LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
@@ -290,8 +389,7 @@ restart:
 			}
 
 			/* Thread quit pipe has been closed. Killing thread. */
-			ret = sessiond_check_thread_quit_pipe(pollfd, revents);
-			if (ret) {
+			if (pollfd == quit_pipe_read_fd) {
 				goto exit;
 			}
 
@@ -354,9 +452,49 @@ error:
 error_tcp_socket:
 	lttng_poll_clean(&events);
 error_poll_create:
-	DBG("[agent-thread] is cleaning up and stopping.");
-
+	uatomic_set(&agent_tracing_enabled, 0);
+	DBG("[agent-thread] Cleaning up and stopping.");
 	rcu_thread_offline();
 	rcu_unregister_thread();
 	return NULL;
 }
+
+static bool shutdown_agent_management_thread(void *data)
+{
+	struct lttng_pipe *quit_pipe = data;
+	const int write_fd = lttng_pipe_get_writefd(quit_pipe);
+
+	return notify_thread_pipe(write_fd) == 1;
+}
+
+static void cleanup_agent_management_thread(void *data)
+{
+	struct lttng_pipe *quit_pipe = data;
+
+	lttng_pipe_destroy(quit_pipe);
+}
+
+bool launch_agent_management_thread(void)
+{
+	struct lttng_pipe *quit_pipe;
+	struct lttng_thread *thread;
+
+	quit_pipe = lttng_pipe_open(FD_CLOEXEC);
+	if (!quit_pipe) {
+		goto error;
+	}
+	thread = lttng_thread_create("Agent management",
+			thread_agent_management,
+			shutdown_agent_management_thread,
+			cleanup_agent_management_thread,
+			quit_pipe);
+	if (!thread) {
+		goto error;
+	}
+
+	lttng_thread_put(thread);
+	return true;
+error:
+	cleanup_agent_management_thread(quit_pipe);
+	return false;
+}