[lttng-tools.git] / src / common / kernel-consumer / kernel-consumer.c

/*
 * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
 *                      Mathieu Desnoyers <mathieu.desnoyers@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 _GNU_SOURCE
#include <assert.h>
#include <poll.h>
#include <pthread.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/stat.h>

#include <common/common.h>
#include <common/kernel-ctl/kernel-ctl.h>
#include <common/sessiond-comm/sessiond-comm.h>
#include <common/sessiond-comm/relayd.h>
#include <common/compat/fcntl.h>
#include <common/relayd/relayd.h>

#include "kernel-consumer.h"

extern struct lttng_consumer_global_data consumer_data;
extern int consumer_poll_timeout;
extern volatile int consumer_quit;

/*
 * Take a snapshot for a specific fd
 *
 * Returns 0 on success, < 0 on error
 */
int lttng_kconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
		struct lttng_consumer_stream *stream)
{
	int ret = 0;
	int infd = stream->wait_fd;

	ret = kernctl_snapshot(infd);
	if (ret != 0) {
		errno = -ret;
		perror("Getting sub-buffer snapshot.");
	}

	return ret;
}

/*
 * Get the produced position
 *
 * Returns 0 on success, < 0 on error
 */
int lttng_kconsumer_get_produced_snapshot(
		struct lttng_consumer_local_data *ctx,
		struct lttng_consumer_stream *stream,
		unsigned long *pos)
{
	int ret;
	int infd = stream->wait_fd;

	ret = kernctl_snapshot_get_produced(infd, pos);
	if (ret != 0) {
		errno = -ret;
		perror("kernctl_snapshot_get_produced");
	}

	return ret;
}

int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
		int sock, struct pollfd *consumer_sockpoll)
{
	ssize_t ret;
	struct lttcomm_consumer_msg msg;

	ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
	if (ret != sizeof(msg)) {
		lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_CMD);
		return ret;
	}
	if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
		return -ENOENT;
	}

	/* relayd needs RCU read-side protection */
	rcu_read_lock();

	switch (msg.cmd_type) {
	case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
	{
		int fd;
		struct consumer_relayd_sock_pair *relayd;

		DBG("Consumer adding relayd socket");

		/* Get relayd reference if exists. */
		relayd = consumer_find_relayd(msg.u.relayd_sock.net_index);
		if (relayd == NULL) {
			/* Not found. Allocate one. */
			relayd = consumer_allocate_relayd_sock_pair(
					msg.u.relayd_sock.net_index);
			if (relayd == NULL) {
				lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
				goto end_nosignal;
			}
		}

		/* Poll on consumer socket. */
		if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
			return -EINTR;
		}

		/* Get relayd socket from session daemon */
		ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
		if (ret != sizeof(fd)) {
			lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
			goto end_nosignal;
		}

		/* Copy socket information and received FD */
		switch (msg.u.relayd_sock.type) {
		case LTTNG_STREAM_CONTROL:
			/* Copy received lttcomm socket */
			lttcomm_copy_sock(&relayd->control_sock, &msg.u.relayd_sock.sock);

			ret = lttcomm_create_sock(&relayd->control_sock);
			if (ret < 0) {
				goto end_nosignal;
			}

			/* Close the created socket fd which is useless */
			close(relayd->control_sock.fd);

			/* Assign new file descriptor */
			relayd->control_sock.fd = fd;
			break;
		case LTTNG_STREAM_DATA:
			/* Copy received lttcomm socket */
			lttcomm_copy_sock(&relayd->data_sock, &msg.u.relayd_sock.sock);
			ret = lttcomm_create_sock(&relayd->data_sock);
			if (ret < 0) {
				goto end_nosignal;
			}

			/* Close the created socket fd which is useless */
			close(relayd->data_sock.fd);

			/* Assign new file descriptor */
			relayd->data_sock.fd = fd;
			break;
		default:
			ERR("Unknown relayd socket type");
			goto end_nosignal;
		}

		DBG("Consumer %s socket created successfully with net idx %d (fd: %d)",
				msg.u.relayd_sock.type == LTTNG_STREAM_CONTROL ? "control" : "data",
				relayd->net_seq_idx, fd);

		/*
		 * Add relayd socket pair to consumer data hashtable. If object already
		 * exists or on error, the function gracefully returns.
		 */
		consumer_add_relayd(relayd);

		goto end_nosignal;
	}
	case LTTNG_CONSUMER_ADD_CHANNEL:
	{
		struct lttng_consumer_channel *new_channel;

		DBG("consumer_add_channel %d", msg.u.channel.channel_key);
		new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
				-1, -1,
				msg.u.channel.mmap_len,
				msg.u.channel.max_sb_size);
		if (new_channel == NULL) {
			lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
			goto end_nosignal;
		}
		if (ctx->on_recv_channel != NULL) {
			ret = ctx->on_recv_channel(new_channel);
			if (ret == 0) {
				consumer_add_channel(new_channel);
			} else if (ret < 0) {
				goto end_nosignal;
			}
		} else {
			consumer_add_channel(new_channel);
		}
		goto end_nosignal;
	}
	case LTTNG_CONSUMER_ADD_STREAM:
	{
		int fd;
		struct consumer_relayd_sock_pair *relayd = NULL;
		struct lttng_consumer_stream *new_stream;

		/* block */
		if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
			return -EINTR;
		}

		/* Get stream file descriptor from socket */
		ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
		if (ret != sizeof(fd)) {
			lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
			return ret;
		}

		new_stream = consumer_allocate_stream(msg.u.stream.channel_key,
				msg.u.stream.stream_key,
				fd, fd,
				msg.u.stream.state,
				msg.u.stream.mmap_len,
				msg.u.stream.output,
				msg.u.stream.path_name,
				msg.u.stream.uid,
				msg.u.stream.gid,
				msg.u.stream.net_index,
				msg.u.stream.metadata_flag);
		if (new_stream == NULL) {
			lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
			goto end;
		}

		/* The stream is not metadata. Get relayd reference if exists. */
		relayd = consumer_find_relayd(msg.u.stream.net_index);
		if (relayd != NULL) {
			/* Add stream on the relayd */
			pthread_mutex_lock(&relayd->ctrl_sock_mutex);
			ret = relayd_add_stream(&relayd->control_sock,
					msg.u.stream.name, msg.u.stream.path_name,
					&new_stream->relayd_stream_id);
			pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
			if (ret < 0) {
				goto end;
			}
		} else if (msg.u.stream.net_index != -1) {
			ERR("Network sequence index %d unknown. Not adding stream.",
					msg.u.stream.net_index);
			free(new_stream);
			goto end;
		}

		if (ctx->on_recv_stream != NULL) {
			ret = ctx->on_recv_stream(new_stream);
			if (ret == 0) {
				consumer_add_stream(new_stream);
			} else if (ret < 0) {
				goto end;
			}
		} else {
			consumer_add_stream(new_stream);
		}

		DBG("Kernel consumer_add_stream (%d)", fd);
		break;
	}
	case LTTNG_CONSUMER_UPDATE_STREAM:
	{
		if (ctx->on_update_stream != NULL) {
			ret = ctx->on_update_stream(msg.u.stream.stream_key, msg.u.stream.state);
			if (ret == 0) {
				consumer_change_stream_state(msg.u.stream.stream_key, msg.u.stream.state);
			} else if (ret < 0) {
				goto end;
			}
		} else {
			consumer_change_stream_state(msg.u.stream.stream_key,
				msg.u.stream.state);
		}
		break;
	}
	default:
		break;
	}
end:
	/*
	 * Wake-up the other end by writing a null byte in the pipe
	 * (non-blocking). Important note: Because writing into the
	 * pipe is non-blocking (and therefore we allow dropping wakeup
	 * data, as long as there is wakeup data present in the pipe
	 * buffer to wake up the other end), the other end should
	 * perform the following sequence for waiting:
	 * 1) empty the pipe (reads).
	 * 2) perform update operation.
	 * 3) wait on the pipe (poll).
	 */
	do {
		ret = write(ctx->consumer_poll_pipe[1], "", 1);
	} while (ret < 0 && errno == EINTR);
end_nosignal:
	rcu_read_unlock();
	return 0;
}

/*
 * Consume data on a file descriptor and write it on a trace file.
 */
ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
		struct lttng_consumer_local_data *ctx)
{
	unsigned long len;
	int err;
	ssize_t ret = 0;
	int infd = stream->wait_fd;

	DBG("In read_subbuffer (infd : %d)", infd);
	/* Get the next subbuffer */
	err = kernctl_get_next_subbuf(infd);
	if (err != 0) {
		/*
		 * This is a debug message even for single-threaded consumer,
		 * because poll() have more relaxed criterions than get subbuf,
		 * so get_subbuf may fail for short race windows where poll()
		 * would issue wakeups.
		 */
		DBG("Reserving sub buffer failed (everything is normal, "
				"it is due to concurrency)");
		goto end;
	}

	switch (stream->output) {
		case LTTNG_EVENT_SPLICE:
			/* read the whole subbuffer */
			err = kernctl_get_padded_subbuf_size(infd, &len);
			if (err != 0) {
				errno = -ret;
				perror("Getting sub-buffer len failed.");
				goto end;
			}

			/* splice the subbuffer to the tracefile */
			ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, len);
			if (ret != len) {
				/*
				 * display the error but continue processing to try
				 * to release the subbuffer
				 */
				ERR("Error splicing to tracefile (ret: %ld != len: %ld)",
						ret, len);
			}

			break;
		case LTTNG_EVENT_MMAP:
			/* read the used subbuffer size */
			err = kernctl_get_padded_subbuf_size(infd, &len);
			if (err != 0) {
				errno = -ret;
				perror("Getting sub-buffer len failed.");
				goto end;
			}
			/* write the subbuffer to the tracefile */
			ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
			if (ret != len) {
				/*
				 * display the error but continue processing to try
				 * to release the subbuffer
				 */
				ERR("Error writing to tracefile");
			}
			break;
		default:
			ERR("Unknown output method");
			ret = -1;
	}

	err = kernctl_put_next_subbuf(infd);
	if (err != 0) {
		errno = -ret;
		if (errno == EFAULT) {
			perror("Error in unreserving sub buffer\n");
		} else if (errno == EIO) {
			/* Should never happen with newer LTTng versions */
			perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
		}
		goto end;
	}

end:
	return ret;
}

int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
{
	int ret;

	/* Opening the tracefile in write mode */
	if (strlen(stream->path_name) > 0 && stream->net_seq_idx == -1) {
		ret = run_as_open(stream->path_name,
				O_WRONLY|O_CREAT|O_TRUNC,
				S_IRWXU|S_IRWXG|S_IRWXO,
				stream->uid, stream->gid);
		if (ret < 0) {
			ERR("Opening %s", stream->path_name);
			perror("open");
			goto error;
		}
		stream->out_fd = ret;
	}

	if (stream->output == LTTNG_EVENT_MMAP) {
		/* get the len of the mmap region */
		unsigned long mmap_len;

		ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
		if (ret != 0) {
			errno = -ret;
			perror("kernctl_get_mmap_len");
			goto error_close_fd;
		}
		stream->mmap_len = (size_t) mmap_len;

		stream->mmap_base = mmap(NULL, stream->mmap_len,
				PROT_READ, MAP_PRIVATE, stream->wait_fd, 0);
		if (stream->mmap_base == MAP_FAILED) {
			perror("Error mmaping");
			ret = -1;
			goto error_close_fd;
		}
	}

	/* we return 0 to let the library handle the FD internally */
	return 0;

error_close_fd:
	{
		int err;

		err = close(stream->out_fd);
		assert(!err);
	}
error:
	return ret;
}
Commit	Line	Data
3bd1e081 MD	1	/*
	2	* Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
	3	* Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	4	*
d14d33bf AM	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License, version 2 only,
	7	* as published by the Free Software Foundation.
3bd1e081 MD	8	*
	9	* This program is distributed in the hope that it will be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
d14d33bf AM	14	* You should have received a copy of the GNU General Public License along
	15	* with this program; if not, write to the Free Software Foundation, Inc.,
	16	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
3bd1e081 MD	17	*/
	18
	19	#define _GNU_SOURCE
	20	#include <assert.h>
3bd1e081 MD	21	#include <poll.h>
	22	#include <pthread.h>
	23	#include <stdlib.h>
	24	#include <string.h>
	25	#include <sys/mman.h>
	26	#include <sys/socket.h>
	27	#include <sys/types.h>
	28	#include <unistd.h>
dbb5dfe6	29	#include <sys/stat.h>
3bd1e081	30
990570ed	31	#include <common/common.h>
10a8a223	32	#include <common/kernel-ctl/kernel-ctl.h>
10a8a223	33	#include <common/sessiond-comm/sessiond-comm.h>
00e2e675	34	#include <common/sessiond-comm/relayd.h>
dbb5dfe6	35	#include <common/compat/fcntl.h>
00e2e675	36	#include <common/relayd/relayd.h>
0857097f	37
10a8a223	38	#include "kernel-consumer.h"
3bd1e081 MD	39
	40	extern struct lttng_consumer_global_data consumer_data;
	41	extern int consumer_poll_timeout;
	42	extern volatile int consumer_quit;
	43
3bd1e081 MD	44	/*
	45	* Take a snapshot for a specific fd
	46	*
	47	* Returns 0 on success, < 0 on error
	48	*/
	49	int lttng_kconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
	50	struct lttng_consumer_stream *stream)
	51	{
	52	int ret = 0;
	53	int infd = stream->wait_fd;
	54
	55	ret = kernctl_snapshot(infd);
	56	if (ret != 0) {
87dc6a9c	57	errno = -ret;
3bd1e081 MD	58	perror("Getting sub-buffer snapshot.");
	59	}
	60
	61	return ret;
	62	}
	63
	64	/*
	65	* Get the produced position
	66	*
	67	* Returns 0 on success, < 0 on error
	68	*/
	69	int lttng_kconsumer_get_produced_snapshot(
	70	struct lttng_consumer_local_data *ctx,
	71	struct lttng_consumer_stream *stream,
	72	unsigned long *pos)
	73	{
	74	int ret;
	75	int infd = stream->wait_fd;
	76
	77	ret = kernctl_snapshot_get_produced(infd, pos);
	78	if (ret != 0) {
87dc6a9c	79	errno = -ret;
3bd1e081 MD	80	perror("kernctl_snapshot_get_produced");
	81	}
	82
	83	return ret;
	84	}
	85
	86	int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
	87	int sock, struct pollfd *consumer_sockpoll)
	88	{
	89	ssize_t ret;
	90	struct lttcomm_consumer_msg msg;
	91
	92	ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
	93	if (ret != sizeof(msg)) {
f2fc6720	94	lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_CMD);
3bd1e081 MD	95	return ret;
	96	}
	97	if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
	98	return -ENOENT;
	99	}
	100
b0b335c8 MD	101	/* relayd needs RCU read-side protection */
	102	rcu_read_lock();
	103
3bd1e081	104	switch (msg.cmd_type) {
00e2e675 DG	105	case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
	106	{
	107	int fd;
	108	struct consumer_relayd_sock_pair *relayd;
	109
	110	DBG("Consumer adding relayd socket");
	111
	112	/* Get relayd reference if exists. */
	113	relayd = consumer_find_relayd(msg.u.relayd_sock.net_index);
	114	if (relayd == NULL) {
	115	/* Not found. Allocate one. */
	116	relayd = consumer_allocate_relayd_sock_pair(
	117	msg.u.relayd_sock.net_index);
	118	if (relayd == NULL) {
	119	lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
	120	goto end_nosignal;
	121	}
	122	}
	123
	124	/* Poll on consumer socket. */
	125	if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
	126	return -EINTR;
	127	}
	128
	129	/* Get relayd socket from session daemon */
	130	ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
	131	if (ret != sizeof(fd)) {
	132	lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
	133	goto end_nosignal;
	134	}
	135
	136	/* Copy socket information and received FD */
	137	switch (msg.u.relayd_sock.type) {
	138	case LTTNG_STREAM_CONTROL:
	139	/* Copy received lttcomm socket */
	140	lttcomm_copy_sock(&relayd->control_sock, &msg.u.relayd_sock.sock);
	141
	142	ret = lttcomm_create_sock(&relayd->control_sock);
	143	if (ret < 0) {
	144	goto end_nosignal;
	145	}
	146
	147	/* Close the created socket fd which is useless */
	148	close(relayd->control_sock.fd);
	149
	150	/* Assign new file descriptor */
	151	relayd->control_sock.fd = fd;
	152	break;
	153	case LTTNG_STREAM_DATA:
	154	/* Copy received lttcomm socket */
	155	lttcomm_copy_sock(&relayd->data_sock, &msg.u.relayd_sock.sock);
	156	ret = lttcomm_create_sock(&relayd->data_sock);
	157	if (ret < 0) {
	158	goto end_nosignal;
	159	}
	160
	161	/* Close the created socket fd which is useless */
	162	close(relayd->data_sock.fd);
	163
	164	/* Assign new file descriptor */
	165	relayd->data_sock.fd = fd;
	166	break;
	167	default:
	168	ERR("Unknown relayd socket type");
169	goto end_nosignal;
170	}
171
172	DBG("Consumer %s socket created successfully with net idx %d (fd: %d)",
173	msg.u.relayd_sock.type == LTTNG_STREAM_CONTROL ? "control" : "data",
174	relayd->net_seq_idx, fd);
175
176	/*
177	* Add relayd socket pair to consumer data hashtable. If object already
178	* exists or on error, the function gracefully returns.
179	*/
180	consumer_add_relayd(relayd);
181
182	goto end_nosignal;
183	}
3bd1e081 MD	184	case LTTNG_CONSUMER_ADD_CHANNEL:
	185	{
	186	struct lttng_consumer_channel *new_channel;
	187
	188	DBG("consumer_add_channel %d", msg.u.channel.channel_key);
	189	new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
	190	-1, -1,
	191	msg.u.channel.mmap_len,
	192	msg.u.channel.max_sb_size);
	193	if (new_channel == NULL) {
	194	lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
	195	goto end_nosignal;
	196	}
	197	if (ctx->on_recv_channel != NULL) {
	198	ret = ctx->on_recv_channel(new_channel);
	199	if (ret == 0) {
	200	consumer_add_channel(new_channel);
	201	} else if (ret < 0) {
	202	goto end_nosignal;
	203	}
	204	} else {
	205	consumer_add_channel(new_channel);
	206	}
	207	goto end_nosignal;
	208	}
	209	case LTTNG_CONSUMER_ADD_STREAM:
	210	{
f2fc6720	211	int fd;
00e2e675 DG	212	struct consumer_relayd_sock_pair *relayd = NULL;
00e2e675 DG	213	struct lttng_consumer_stream *new_stream;
3bd1e081 MD	214
	215	/* block */
	216	if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
	217	return -EINTR;
	218	}
00e2e675 DG	219
00e2e675 DG	220	/* Get stream file descriptor from socket */
f2fc6720 MD	221	ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
f2fc6720 MD	222	if (ret != sizeof(fd)) {
3bd1e081 MD	223	lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
	224	return ret;
	225	}
3bd1e081	226
3bd1e081 MD	227	new_stream = consumer_allocate_stream(msg.u.stream.channel_key,
3bd1e081 MD	228	msg.u.stream.stream_key,
f2fc6720	229	fd, fd,
3bd1e081 MD	230	msg.u.stream.state,
	231	msg.u.stream.mmap_len,
	232	msg.u.stream.output,
6df2e2c9 MD	233	msg.u.stream.path_name,
6df2e2c9 MD	234	msg.u.stream.uid,
00e2e675 DG	235	msg.u.stream.gid,
	236	msg.u.stream.net_index,
	237	msg.u.stream.metadata_flag);
3bd1e081 MD	238	if (new_stream == NULL) {
	239	lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
	240	goto end;
	241	}
00e2e675 DG	242
	243	/* The stream is not metadata. Get relayd reference if exists. */
	244	relayd = consumer_find_relayd(msg.u.stream.net_index);
	245	if (relayd != NULL) {
	246	/* Add stream on the relayd */
	247	pthread_mutex_lock(&relayd->ctrl_sock_mutex);
	248	ret = relayd_add_stream(&relayd->control_sock,
	249	msg.u.stream.name, msg.u.stream.path_name,
	250	&new_stream->relayd_stream_id);
	251	pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
	252	if (ret < 0) {
	253	goto end;
	254	}
	255	} else if (msg.u.stream.net_index != -1) {
	256	ERR("Network sequence index %d unknown. Not adding stream.",
	257	msg.u.stream.net_index);
	258	free(new_stream);
	259	goto end;
	260	}
	261
3bd1e081 MD	262	if (ctx->on_recv_stream != NULL) {
	263	ret = ctx->on_recv_stream(new_stream);
	264	if (ret == 0) {
	265	consumer_add_stream(new_stream);
	266	} else if (ret < 0) {
	267	goto end;
	268	}
	269	} else {
	270	consumer_add_stream(new_stream);
	271	}
00e2e675 DG	272
00e2e675 DG	273	DBG("Kernel consumer_add_stream (%d)", fd);
3bd1e081 MD	274	break;
	275	}
	276	case LTTNG_CONSUMER_UPDATE_STREAM:
	277	{
	278	if (ctx->on_update_stream != NULL) {
	279	ret = ctx->on_update_stream(msg.u.stream.stream_key, msg.u.stream.state);
	280	if (ret == 0) {
	281	consumer_change_stream_state(msg.u.stream.stream_key, msg.u.stream.state);
	282	} else if (ret < 0) {
	283	goto end;
	284	}
	285	} else {
	286	consumer_change_stream_state(msg.u.stream.stream_key,
	287	msg.u.stream.state);
	288	}
	289	break;
	290	}
	291	default:
	292	break;
	293	}
	294	end:
04fdd819 MD	295	/*
	296	* Wake-up the other end by writing a null byte in the pipe
	297	* (non-blocking). Important note: Because writing into the
	298	* pipe is non-blocking (and therefore we allow dropping wakeup
	299	* data, as long as there is wakeup data present in the pipe
	300	* buffer to wake up the other end), the other end should
	301	* perform the following sequence for waiting:
	302	* 1) empty the pipe (reads).
	303	* 2) perform update operation.
	304	* 3) wait on the pipe (poll).
	305	*/
	306	do {
	307	ret = write(ctx->consumer_poll_pipe[1], "", 1);
6f94560a	308	} while (ret < 0 && errno == EINTR);
3bd1e081	309	end_nosignal:
b0b335c8	310	rcu_read_unlock();
3bd1e081 MD	311	return 0;
3bd1e081 MD	312	}
d41f73b7 MD	313
	314	/*
	315	* Consume data on a file descriptor and write it on a trace file.
	316	*/
4078b776	317	ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
d41f73b7 MD	318	struct lttng_consumer_local_data *ctx)
	319	{
	320	unsigned long len;
	321	int err;
4078b776	322	ssize_t ret = 0;
d41f73b7 MD	323	int infd = stream->wait_fd;
	324
	325	DBG("In read_subbuffer (infd : %d)", infd);
	326	/* Get the next subbuffer */
	327	err = kernctl_get_next_subbuf(infd);
	328	if (err != 0) {
d41f73b7 MD	329	/*
	330	* This is a debug message even for single-threaded consumer,
	331	* because poll() have more relaxed criterions than get subbuf,
	332	* so get_subbuf may fail for short race windows where poll()
	333	* would issue wakeups.
	334	*/
	335	DBG("Reserving sub buffer failed (everything is normal, "
	336	"it is due to concurrency)");
	337	goto end;
	338	}
	339
	340	switch (stream->output) {
	341	case LTTNG_EVENT_SPLICE:
	342	/* read the whole subbuffer */
	343	err = kernctl_get_padded_subbuf_size(infd, &len);
	344	if (err != 0) {
87dc6a9c	345	errno = -ret;
d41f73b7 MD	346	perror("Getting sub-buffer len failed.");
	347	goto end;
	348	}
	349
	350	/* splice the subbuffer to the tracefile */
	351	ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, len);
47e81c02	352	if (ret != len) {
d41f73b7 MD	353	/*
	354	* display the error but continue processing to try
	355	* to release the subbuffer
	356	*/
00e2e675 DG	357	ERR("Error splicing to tracefile (ret: %ld != len: %ld)",
00e2e675 DG	358	ret, len);
d41f73b7	359	}
47e81c02	360
d41f73b7 MD	361	break;
	362	case LTTNG_EVENT_MMAP:
	363	/* read the used subbuffer size */
	364	err = kernctl_get_padded_subbuf_size(infd, &len);
	365	if (err != 0) {
87dc6a9c	366	errno = -ret;
d41f73b7 MD	367	perror("Getting sub-buffer len failed.");
	368	goto end;
	369	}
	370	/* write the subbuffer to the tracefile */
	371	ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
47e81c02	372	if (ret != len) {
d41f73b7 MD	373	/*
	374	* display the error but continue processing to try
	375	* to release the subbuffer
	376	*/
	377	ERR("Error writing to tracefile");
	378	}
	379	break;
	380	default:
	381	ERR("Unknown output method");
	382	ret = -1;
	383	}
	384
	385	err = kernctl_put_next_subbuf(infd);
	386	if (err != 0) {
87dc6a9c	387	errno = -ret;
d41f73b7 MD	388	if (errno == EFAULT) {
	389	perror("Error in unreserving sub buffer\n");
	390	} else if (errno == EIO) {
	391	/* Should never happen with newer LTTng versions */
	392	perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
	393	}
	394	goto end;
	395	}
	396
	397	end:
	398	return ret;
	399	}
	400
	401	int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
	402	{
	403	int ret;
	404
	405	/* Opening the tracefile in write mode */
00e2e675	406	if (strlen(stream->path_name) > 0 && stream->net_seq_idx == -1) {
e11d277b	407	ret = run_as_open(stream->path_name,
60b6c79c MD	408	O_WRONLY\|O_CREAT\|O_TRUNC,
	409	S_IRWXU\|S_IRWXG\|S_IRWXO,
	410	stream->uid, stream->gid);
d41f73b7 MD	411	if (ret < 0) {
	412	ERR("Opening %s", stream->path_name);
	413	perror("open");
	414	goto error;
	415	}
	416	stream->out_fd = ret;
	417	}
	418
	419	if (stream->output == LTTNG_EVENT_MMAP) {
	420	/* get the len of the mmap region */
	421	unsigned long mmap_len;
	422
	423	ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
	424	if (ret != 0) {
87dc6a9c	425	errno = -ret;
d41f73b7 MD	426	perror("kernctl_get_mmap_len");
	427	goto error_close_fd;
	428	}
	429	stream->mmap_len = (size_t) mmap_len;
	430
	431	stream->mmap_base = mmap(NULL, stream->mmap_len,
	432	PROT_READ, MAP_PRIVATE, stream->wait_fd, 0);
	433	if (stream->mmap_base == MAP_FAILED) {
	434	perror("Error mmaping");
	435	ret = -1;
	436	goto error_close_fd;
	437	}
	438	}
	439
	440	/* we return 0 to let the library handle the FD internally */
	441	return 0;
	442
	443	error_close_fd:
	444	{
	445	int err;
	446
	447	err = close(stream->out_fd);
	448	assert(!err);
	449	}
	450	error:
	451	return ret;
	452	}
	453