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

/*
 * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License, version 2 only, as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#define _LGPL_SOURCE
#include <assert.h>

#include <common/common.h>
#include <common/sessiond-comm/sessiond-comm.h>
#include <common/uri.h>
#include <common/utils.h>

#include <common/compat/endian.h>

#include "fd-limit.h"
#include "agent-thread.h"
#include "agent.h"
#include "lttng-sessiond.h"
#include "session.h"
#include "utils.h"

static int agent_tracing_enabled = -1;

/*
 * Note that there is not port here. It's set after this URI is parsed so we
 * can let the user define a custom one. However, localhost is ALWAYS the
 * default listening address.
 */
static const char *default_reg_uri =
	"tcp://" DEFAULT_NETWORK_VIEWER_BIND_ADDRESS;

/*
 * Update agent application using the given socket. This is done just after
 * registration was successful.
 *
 * This is a quite heavy call in terms of locking since the session list lock
 * AND session lock are acquired.
 */
static void update_agent_app(struct agent_app *app)
{
	struct ltt_session *session, *stmp;
	struct ltt_session_list *list;

	list = session_get_list();
	assert(list);

	session_lock_list();
	cds_list_for_each_entry_safe(session, stmp, &list->head, list) {
		session_lock(session);
		if (session->ust_session) {
			struct agent *agt;

			rcu_read_lock();
			agt = trace_ust_find_agent(session->ust_session, app->domain);
			if (agt) {
				agent_update(agt, app->sock->fd);
			}
			rcu_read_unlock();
		}
		session_unlock(session);
	}
	session_unlock_list();
}

/*
 * Create and init socket from uri.
 */
static struct lttcomm_sock *init_tcp_socket(void)
{
	int ret;
	struct lttng_uri *uri = NULL;
	struct lttcomm_sock *sock = NULL;

	/*
	 * This should never fail since the URI is hardcoded and the port is set
	 * before this thread is launched.
	 */
	ret = uri_parse(default_reg_uri, &uri);
	assert(ret);
	assert(config.agent_tcp_port);
	uri->port = config.agent_tcp_port;

	sock = lttcomm_alloc_sock_from_uri(uri);
	uri_free(uri);
	if (sock == NULL) {
		ERR("[agent-thread] agent allocating TCP socket");
		goto error;
	}

	ret = lttcomm_create_sock(sock);
	if (ret < 0) {
		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;
	}

	ret = sock->ops->listen(sock, -1);
	if (ret < 0) {
		goto error;
	}

	DBG("[agent-thread] Listening on TCP port %u and socket %d",
			config.agent_tcp_port, sock->fd);

	return sock;

error:
	if (sock) {
		lttcomm_destroy_sock(sock);
	}
	return NULL;
}

/*
 * Close and destroy the given TCP socket.
 */
static void destroy_tcp_socket(struct lttcomm_sock *sock)
{
	assert(sock);

	DBG3("[agent-thread] Destroy TCP socket on port %u", config.agent_tcp_port);

	/* This will return gracefully if fd is invalid. */
	sock->ops->close(sock);
	lttcomm_destroy_sock(sock);
}

/*
 * Handle a new agent registration using the reg socket. After that, a new
 * agent application is added to the global hash table and attach to an UST app
 * object. If r_app is not NULL, the created app is set to the pointer.
 *
 * Return the new FD created upon accept() on success or else a negative errno
 * value.
 */
static int handle_registration(struct lttcomm_sock *reg_sock,
		struct agent_app **r_app)
{
	int ret;
	pid_t pid;
	uint32_t major_version, minor_version;
	ssize_t size;
	enum lttng_domain_type domain;
	struct agent_app *app;
	struct agent_register_msg msg;
	struct lttcomm_sock *new_sock;

	assert(reg_sock);

	new_sock = reg_sock->ops->accept(reg_sock);
	if (!new_sock) {
		ret = -ENOTCONN;
		goto error;
	}

	size = new_sock->ops->recvmsg(new_sock, &msg, sizeof(msg), 0);
	if (size < sizeof(msg)) {
		ret = -EINVAL;
		goto error_socket;
	}
	domain = be32toh(msg.domain);
	pid = be32toh(msg.pid);
	major_version = be32toh(msg.major_version);
	minor_version = be32toh(msg.minor_version);

	/* Test communication protocol version of the registring agent. */
	if (major_version != AGENT_MAJOR_VERSION) {
		ret = -EINVAL;
		goto error_socket;
	}
	if (minor_version != AGENT_MINOR_VERSION) {
		ret = -EINVAL;
		goto error_socket;
	}

	DBG2("[agent-thread] New registration for pid %d domain %d on socket %d",
			pid, domain, new_sock->fd);

	app = agent_create_app(pid, domain, new_sock);
	if (!app) {
		ret = -ENOMEM;
		goto error_socket;
	}

	/*
	 * Add before assigning the socket value to the UST app so it can be found
	 * concurrently.
	 */
	agent_add_app(app);

	/*
	 * We don't need to attach the agent app to the app. If we ever do so, we
	 * should consider both registration order of agent before app and app
	 * before agent.
	 */

	if (r_app) {
		*r_app = app;
	}

	return new_sock->fd;

error_socket:
	new_sock->ops->close(new_sock);
	lttcomm_destroy_sock(new_sock);
error:
	return ret;
}

bool agent_tracing_is_enabled(void)
{
	int enabled;

	enabled = uatomic_read(&agent_tracing_enabled);
	assert(enabled != -1);
	return enabled == 1;
}

/*
 * This thread manage application notify communication.
 */
void *agent_thread_manage_registration(void *data)
{
	int i, ret, pollfd;
	uint32_t revents, nb_fd;
	struct lttng_poll_event events;
	struct lttcomm_sock *reg_sock;

	DBG("[agent-thread] Manage agent application registration.");

	rcu_register_thread();
	rcu_thread_online();

	/* 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);
	if (ret < 0) {
		goto error_poll_create;
	}

	reg_sock = init_tcp_socket();
	uatomic_set(&agent_tracing_enabled, !!reg_sock);

	/*
	 * Signal that the agent thread is ready. The command thread
	 * may start to query whether or not agent tracing is enabled.
	 */
	sessiond_notify_ready();
	if (!reg_sock) {
		goto error_tcp_socket;
	}

	/* Add TCP socket to poll set. */
	ret = lttng_poll_add(&events, reg_sock->fd,
			LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
	if (ret < 0) {
		goto error;
	}

	while (1) {
		DBG3("[agent-thread] Manage agent polling");

		/* Inifinite blocking call, waiting for transmission */
restart:
		ret = lttng_poll_wait(&events, -1);
		DBG3("[agent-thread] Manage agent return from poll on %d fds",
				LTTNG_POLL_GETNB(&events));
		if (ret < 0) {
			/*
			 * Restart interrupted system call.
			 */
			if (errno == EINTR) {
				goto restart;
			}
			goto error;
		}
		nb_fd = ret;
		DBG3("[agent-thread] %d fd ready", nb_fd);

		for (i = 0; i < nb_fd; i++) {
			/* Fetch once the poll data */
			revents = LTTNG_POLL_GETEV(&events, i);
			pollfd = LTTNG_POLL_GETFD(&events, i);

			if (!revents) {
				/* No activity for this FD (poll implementation). */
				continue;
			}

			/* Thread quit pipe has been closed. Killing thread. */
			ret = sessiond_check_thread_quit_pipe(pollfd, revents);
			if (ret) {
				goto exit;
			}

			if (revents & LPOLLIN) {
				int new_fd;
				struct agent_app *app = NULL;

				assert(pollfd == reg_sock->fd);
				new_fd = handle_registration(reg_sock, &app);
				if (new_fd < 0) {
					continue;
				}
				/* Should not have a NULL app on success. */
				assert(app);

				/*
				 * Since this is a command socket (write then read),
				 * only add poll error event to only detect shutdown.
				 */
				ret = lttng_poll_add(&events, new_fd,
						LPOLLERR | LPOLLHUP | LPOLLRDHUP);
				if (ret < 0) {
					agent_destroy_app_by_sock(new_fd);
					continue;
				}

				/* Update newly registered app. */
				update_agent_app(app);

				/* On failure, the poll will detect it and clean it up. */
				ret = agent_send_registration_done(app);
				if (ret < 0) {
					/* Removing from the poll set */
					ret = lttng_poll_del(&events, new_fd);
					if (ret < 0) {
						goto error;
					}
					agent_destroy_app_by_sock(new_fd);
					continue;
				}
			} else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
				/* Removing from the poll set */
				ret = lttng_poll_del(&events, pollfd);
				if (ret < 0) {
					goto error;
				}
				agent_destroy_app_by_sock(pollfd);
			} else {
				ERR("Unexpected poll events %u for sock %d", revents, pollfd);
				goto error;
			}
		}
	}

exit:
	uatomic_set(&agent_tracing_enabled, 0);
	/* Whatever happens, try to delete it and exit. */
	(void) lttng_poll_del(&events, reg_sock->fd);
error:
	destroy_tcp_socket(reg_sock);
error_tcp_socket:
	lttng_poll_clean(&events);
error_poll_create:
	DBG("[agent-thread] is cleaning up and stopping.");

	rcu_thread_offline();
	rcu_unregister_thread();
	return NULL;
}
Commit	Line	Data
4d076222 DG	1	/*
	2	* Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
	3	*
	4	* This program is free software; you can redistribute it and/or modify it
	5	* under the terms of the GNU General Public License, version 2 only, as
	6	* published by the Free Software Foundation.
	7	*
	8	* This program is distributed in the hope that it will be useful, but WITHOUT
	9	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	10	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	11	* more details.
	12	*
	13	* You should have received a copy of the GNU General Public License along with
	14	* this program; if not, write to the Free Software Foundation, Inc., 51
	15	* Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	16	*/
	17
6c1c0768	18	#define _LGPL_SOURCE
4d076222 DG	19	#include <assert.h>
	20
	21	#include <common/common.h>
	22	#include <common/sessiond-comm/sessiond-comm.h>
	23	#include <common/uri.h>
	24	#include <common/utils.h>
	25
f263b7fd JD	26	#include <common/compat/endian.h>
f263b7fd JD	27
4d076222	28	#include "fd-limit.h"
022d91ba	29	#include "agent-thread.h"
6a4e4039	30	#include "agent.h"
4d076222	31	#include "lttng-sessiond.h"
f20baf8e DG	32	#include "session.h"
f20baf8e DG	33	#include "utils.h"
4d076222	34
f28f9e44 JG	35	static int agent_tracing_enabled = -1;
f28f9e44 JG	36
4d076222 DG	37	/*
	38	* Note that there is not port here. It's set after this URI is parsed so we
	39	* can let the user define a custom one. However, localhost is ALWAYS the
	40	* default listening address.
	41	*/
fa91dc52 MD	42	static const char *default_reg_uri =
fa91dc52 MD	43	"tcp://" DEFAULT_NETWORK_VIEWER_BIND_ADDRESS;
4d076222	44
f20baf8e	45	/*
022d91ba	46	* Update agent application using the given socket. This is done just after
f20baf8e DG	47	* registration was successful.
	48	*
	49	* This is a quite heavy call in terms of locking since the session list lock
	50	* AND session lock are acquired.
	51	*/
fefd409b	52	static void update_agent_app(struct agent_app *app)
f20baf8e DG	53	{
	54	struct ltt_session session, stmp;
	55	struct ltt_session_list *list;
	56
	57	list = session_get_list();
	58	assert(list);
	59
	60	session_lock_list();
	61	cds_list_for_each_entry_safe(session, stmp, &list->head, list) {
	62	session_lock(session);
	63	if (session->ust_session) {
fefd409b DG	64	struct agent *agt;
fefd409b DG	65
4da703ad	66	rcu_read_lock();
fefd409b DG	67	agt = trace_ust_find_agent(session->ust_session, app->domain);
	68	if (agt) {
	69	agent_update(agt, app->sock->fd);
	70	}
4da703ad	71	rcu_read_unlock();
f20baf8e DG	72	}
	73	session_unlock(session);
	74	}
	75	session_unlock_list();
	76	}
	77
4d076222 DG	78	/*
	79	* Create and init socket from uri.
	80	*/
	81	static struct lttcomm_sock *init_tcp_socket(void)
	82	{
	83	int ret;
	84	struct lttng_uri *uri = NULL;
	85	struct lttcomm_sock *sock = NULL;
	86
	87	/*
	88	* This should never fail since the URI is hardcoded and the port is set
	89	* before this thread is launched.
	90	*/
	91	ret = uri_parse(default_reg_uri, &uri);
	92	assert(ret);
e6142f2e JG	93	assert(config.agent_tcp_port);
e6142f2e JG	94	uri->port = config.agent_tcp_port;
4d076222 DG	95
	96	sock = lttcomm_alloc_sock_from_uri(uri);
	97	uri_free(uri);
	98	if (sock == NULL) {
022d91ba	99	ERR("[agent-thread] agent allocating TCP socket");
4d076222 DG	100	goto error;
	101	}
	102
	103	ret = lttcomm_create_sock(sock);
	104	if (ret < 0) {
	105	goto error;
	106	}
	107
	108	ret = sock->ops->bind(sock);
	109	if (ret < 0) {
022d91ba	110	WARN("Another session daemon is using this agent port. Agent support "
5368d366	111	"will be deactivated to prevent interfering with the tracing.");
4d076222 DG	112	goto error;
	113	}
	114
	115	ret = sock->ops->listen(sock, -1);
	116	if (ret < 0) {
	117	goto error;
	118	}
	119
022d91ba	120	DBG("[agent-thread] Listening on TCP port %u and socket %d",
e6142f2e	121	config.agent_tcp_port, sock->fd);
4d076222 DG	122
	123	return sock;
	124
	125	error:
	126	if (sock) {
	127	lttcomm_destroy_sock(sock);
	128	}
	129	return NULL;
	130	}
	131
	132	/*
	133	* Close and destroy the given TCP socket.
	134	*/
	135	static void destroy_tcp_socket(struct lttcomm_sock *sock)
	136	{
	137	assert(sock);
	138
e6142f2e	139	DBG3("[agent-thread] Destroy TCP socket on port %u", config.agent_tcp_port);
4d076222 DG	140
	141	/* This will return gracefully if fd is invalid. */
	142	sock->ops->close(sock);
	143	lttcomm_destroy_sock(sock);
	144	}
	145
f20baf8e	146	/*
022d91ba DG	147	* Handle a new agent registration using the reg socket. After that, a new
022d91ba DG	148	* agent application is added to the global hash table and attach to an UST app
1b500e7a	149	* object. If r_app is not NULL, the created app is set to the pointer.
f20baf8e DG	150	*
	151	* Return the new FD created upon accept() on success or else a negative errno
	152	* value.
	153	*/
1b500e7a	154	static int handle_registration(struct lttcomm_sock *reg_sock,
022d91ba	155	struct agent_app **r_app)
f20baf8e DG	156	{
	157	int ret;
	158	pid_t pid;
9474416f	159	uint32_t major_version, minor_version;
f20baf8e	160	ssize_t size;
fefd409b	161	enum lttng_domain_type domain;
022d91ba DG	162	struct agent_app *app;
022d91ba DG	163	struct agent_register_msg msg;
f20baf8e DG	164	struct lttcomm_sock *new_sock;
	165
	166	assert(reg_sock);
	167
	168	new_sock = reg_sock->ops->accept(reg_sock);
	169	if (!new_sock) {
	170	ret = -ENOTCONN;
	171	goto error;
	172	}
	173
	174	size = new_sock->ops->recvmsg(new_sock, &msg, sizeof(msg), 0);
	175	if (size < sizeof(msg)) {
79865500	176	ret = -EINVAL;
f20baf8e DG	177	goto error_socket;
f20baf8e DG	178	}
fefd409b	179	domain = be32toh(msg.domain);
f20baf8e	180	pid = be32toh(msg.pid);
9474416f DG	181	major_version = be32toh(msg.major_version);
	182	minor_version = be32toh(msg.minor_version);
	183
	184	/* Test communication protocol version of the registring agent. */
	185	if (major_version != AGENT_MAJOR_VERSION) {
	186	ret = -EINVAL;
	187	goto error_socket;
	188	}
	189	if (minor_version != AGENT_MINOR_VERSION) {
	190	ret = -EINVAL;
	191	goto error_socket;
	192	}
f20baf8e	193
fefd409b DG	194	DBG2("[agent-thread] New registration for pid %d domain %d on socket %d",
fefd409b DG	195	pid, domain, new_sock->fd);
f20baf8e	196
fefd409b	197	app = agent_create_app(pid, domain, new_sock);
f20baf8e DG	198	if (!app) {
	199	ret = -ENOMEM;
	200	goto error_socket;
	201	}
	202
	203	/*
	204	* Add before assigning the socket value to the UST app so it can be found
	205	* concurrently.
	206	*/
022d91ba	207	agent_add_app(app);
f20baf8e DG	208
f20baf8e DG	209	/*
022d91ba DG	210	* We don't need to attach the agent app to the app. If we ever do so, we
	211	* should consider both registration order of agent before app and app
	212	* before agent.
f20baf8e	213	*/
f20baf8e	214
1b500e7a DG	215	if (r_app) {
	216	*r_app = app;
	217	}
	218
f20baf8e DG	219	return new_sock->fd;
	220
	221	error_socket:
	222	new_sock->ops->close(new_sock);
	223	lttcomm_destroy_sock(new_sock);
	224	error:
	225	return ret;
	226	}
	227
f28f9e44 JG	228	bool agent_tracing_is_enabled(void)
	229	{
	230	int enabled;
	231
	232	enabled = uatomic_read(&agent_tracing_enabled);
	233	assert(enabled != -1);
	234	return enabled == 1;
	235	}
	236
4d076222 DG	237	/*
	238	* This thread manage application notify communication.
	239	*/
022d91ba	240	void agent_thread_manage_registration(void data)
4d076222 DG	241	{
	242	int i, ret, pollfd;
	243	uint32_t revents, nb_fd;
	244	struct lttng_poll_event events;
	245	struct lttcomm_sock *reg_sock;
	246
022d91ba	247	DBG("[agent-thread] Manage agent application registration.");
4d076222 DG	248
	249	rcu_register_thread();
	250	rcu_thread_online();
	251
022d91ba DG	252	/* Agent initialization call MUST be called before starting the thread. */
022d91ba DG	253	assert(agent_apps_ht_by_sock);
f20baf8e	254
4d076222 DG	255	/* Create pollset with size 2, quit pipe and socket. */
	256	ret = sessiond_set_thread_pollset(&events, 2);
	257	if (ret < 0) {
	258	goto error_poll_create;
	259	}
	260
	261	reg_sock = init_tcp_socket();
f28f9e44 JG	262	uatomic_set(&agent_tracing_enabled, !!reg_sock);
	263
	264	/*
	265	* Signal that the agent thread is ready. The command thread
	266	* may start to query whether or not agent tracing is enabled.
	267	*/
7eac7803	268	sessiond_notify_ready();
4d076222 DG	269	if (!reg_sock) {
	270	goto error_tcp_socket;
	271	}
	272
427392b4	273	/* Add TCP socket to poll set. */
4d076222 DG	274	ret = lttng_poll_add(&events, reg_sock->fd,
	275	LPOLLIN \| LPOLLERR \| LPOLLHUP \| LPOLLRDHUP);
	276	if (ret < 0) {
	277	goto error;
	278	}
	279
	280	while (1) {
546f19b5	281	DBG3("[agent-thread] Manage agent polling");
4d076222 DG	282
	283	/* Inifinite blocking call, waiting for transmission */
	284	restart:
	285	ret = lttng_poll_wait(&events, -1);
7fa2082e MD	286	DBG3("[agent-thread] Manage agent return from poll on %d fds",
7fa2082e MD	287	LTTNG_POLL_GETNB(&events));
4d076222 DG	288	if (ret < 0) {
	289	/*
	290	* Restart interrupted system call.
	291	*/
	292	if (errno == EINTR) {
	293	goto restart;
	294	}
	295	goto error;
	296	}
	297	nb_fd = ret;
022d91ba	298	DBG3("[agent-thread] %d fd ready", nb_fd);
4d076222 DG	299
	300	for (i = 0; i < nb_fd; i++) {
	301	/* Fetch once the poll data */
	302	revents = LTTNG_POLL_GETEV(&events, i);
	303	pollfd = LTTNG_POLL_GETFD(&events, i);
	304
fd20dac9 MD	305	if (!revents) {
	306	/* No activity for this FD (poll implementation). */
	307	continue;
	308	}
	309
4d076222 DG	310	/* Thread quit pipe has been closed. Killing thread. */
	311	ret = sessiond_check_thread_quit_pipe(pollfd, revents);
	312	if (ret) {
	313	goto exit;
	314	}
	315
03e43155	316	if (revents & LPOLLIN) {
f20baf8e	317	int new_fd;
022d91ba	318	struct agent_app *app = NULL;
f20baf8e	319
f20baf8e	320	assert(pollfd == reg_sock->fd);
1b500e7a	321	new_fd = handle_registration(reg_sock, &app);
f20baf8e	322	if (new_fd < 0) {
f20baf8e DG	323	continue;
f20baf8e DG	324	}
1b500e7a DG	325	/* Should not have a NULL app on success. */
1b500e7a DG	326	assert(app);
f20baf8e	327
03e43155 MD	328	/*
	329	* Since this is a command socket (write then read),
	330	* only add poll error event to only detect shutdown.
	331	*/
f20baf8e DG	332	ret = lttng_poll_add(&events, new_fd,
	333	LPOLLERR \| LPOLLHUP \| LPOLLRDHUP);
	334	if (ret < 0) {
6a4e4039	335	agent_destroy_app_by_sock(new_fd);
f20baf8e DG	336	continue;
	337	}
	338
	339	/* Update newly registered app. */
fefd409b	340	update_agent_app(app);
1b500e7a DG	341
1b500e7a DG	342	/* On failure, the poll will detect it and clean it up. */
03e43155 MD	343	ret = agent_send_registration_done(app);
	344	if (ret < 0) {
	345	/* Removing from the poll set */
	346	ret = lttng_poll_del(&events, new_fd);
	347	if (ret < 0) {
	348	goto error;
	349	}
	350	agent_destroy_app_by_sock(new_fd);
	351	continue;
	352	}
	353	} else if (revents & (LPOLLERR \| LPOLLHUP \| LPOLLRDHUP)) {
	354	/* Removing from the poll set */
	355	ret = lttng_poll_del(&events, pollfd);
	356	if (ret < 0) {
	357	goto error;
	358	}
	359	agent_destroy_app_by_sock(pollfd);
4d076222	360	} else {
03e43155 MD	361	ERR("Unexpected poll events %u for sock %d", revents, pollfd);
03e43155 MD	362	goto error;
4d076222 DG	363	}
	364	}
	365	}
	366
	367	exit:
f28f9e44	368	uatomic_set(&agent_tracing_enabled, 0);
f20baf8e DG	369	/* Whatever happens, try to delete it and exit. */
f20baf8e DG	370	(void) lttng_poll_del(&events, reg_sock->fd);
4d076222 DG	371	error:
	372	destroy_tcp_socket(reg_sock);
	373	error_tcp_socket:
	374	lttng_poll_clean(&events);
	375	error_poll_create:
022d91ba	376	DBG("[agent-thread] is cleaning up and stopping.");
4d076222 DG	377
	378	rcu_thread_offline();
	379	rcu_unregister_thread();
	380	return NULL;
	381	}