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

/*
 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
 *
 * 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
#define _LGPL_SOURCE
#include <inttypes.h>
#include <string.h>
#include <unistd.h>

#include <common/common.h>
#include <common/defaults.h>
#include <common/sessiond-comm/sessiond-comm.h>

#include "channel.h"
#include "lttng-sessiond.h"
#include "kernel.h"
#include "ust-ctl.h"
#include "utils.h"
#include "ust-app.h"

/*
 * Return allocated channel attributes.
 */
struct lttng_channel *channel_new_default_attr(int dom,
		enum lttng_buffer_type type)
{
	struct lttng_channel *chan;

	chan = zmalloc(sizeof(struct lttng_channel));
	if (chan == NULL) {
		PERROR("zmalloc channel init");
		goto error_alloc;
	}

	if (snprintf(chan->name, sizeof(chan->name), "%s",
				DEFAULT_CHANNEL_NAME) < 0) {
		PERROR("snprintf default channel name");
		goto error;
	}

	/* Same for all domains. */
	chan->attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
	chan->attr.tracefile_size = DEFAULT_CHANNEL_TRACEFILE_SIZE;
	chan->attr.tracefile_count = DEFAULT_CHANNEL_TRACEFILE_COUNT;

	switch (dom) {
	case LTTNG_DOMAIN_KERNEL:
		assert(type == LTTNG_BUFFER_GLOBAL);
		chan->attr.subbuf_size =
			default_get_kernel_channel_subbuf_size();
		chan->attr.num_subbuf = DEFAULT_KERNEL_CHANNEL_SUBBUF_NUM;
		chan->attr.output = DEFAULT_KERNEL_CHANNEL_OUTPUT;
		chan->attr.switch_timer_interval = DEFAULT_KERNEL_CHANNEL_SWITCH_TIMER;
		chan->attr.read_timer_interval = DEFAULT_KERNEL_CHANNEL_READ_TIMER;
		chan->attr.live_timer_interval = DEFAULT_KERNEL_CHANNEL_LIVE_TIMER;
		break;
	case LTTNG_DOMAIN_UST:
		switch (type) {
		case LTTNG_BUFFER_PER_UID:
			chan->attr.subbuf_size = default_get_ust_uid_channel_subbuf_size();
			chan->attr.num_subbuf = DEFAULT_UST_UID_CHANNEL_SUBBUF_NUM;
			chan->attr.output = DEFAULT_UST_UID_CHANNEL_OUTPUT;
			chan->attr.switch_timer_interval =
				DEFAULT_UST_UID_CHANNEL_SWITCH_TIMER;
			chan->attr.read_timer_interval =
				DEFAULT_UST_UID_CHANNEL_READ_TIMER;
			chan->attr.live_timer_interval =
				DEFAULT_UST_UID_CHANNEL_LIVE_TIMER;
			break;
		case LTTNG_BUFFER_PER_PID:
		default:
			chan->attr.subbuf_size = default_get_ust_pid_channel_subbuf_size();
			chan->attr.num_subbuf = DEFAULT_UST_PID_CHANNEL_SUBBUF_NUM;
			chan->attr.output = DEFAULT_UST_PID_CHANNEL_OUTPUT;
			chan->attr.switch_timer_interval =
				DEFAULT_UST_PID_CHANNEL_SWITCH_TIMER;
			chan->attr.read_timer_interval =
				DEFAULT_UST_PID_CHANNEL_READ_TIMER;
			chan->attr.live_timer_interval =
				DEFAULT_UST_UID_CHANNEL_LIVE_TIMER;
			break;
		}
		break;
	default:
		goto error;	/* Not implemented */
	}

	return chan;

error:
	free(chan);
error_alloc:
	return NULL;
}

/*
 * Disable kernel channel of the kernel session.
 */
int channel_kernel_disable(struct ltt_kernel_session *ksession,
		char *channel_name)
{
	int ret;
	struct ltt_kernel_channel *kchan;

	assert(ksession);
	assert(channel_name);

	kchan = trace_kernel_get_channel_by_name(channel_name, ksession);
	if (kchan == NULL) {
		ret = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
		goto error;
	}

	/* Only if channel is enabled disable it. */
	if (kchan->enabled == 1) {
		ret = kernel_disable_channel(kchan);
		if (ret < 0 && ret != -EEXIST) {
			ret = LTTNG_ERR_KERN_CHAN_DISABLE_FAIL;
			goto error;
		}
	}

	ret = LTTNG_OK;

error:
	return ret;
}

/*
 * Enable kernel channel of the kernel session.
 */
int channel_kernel_enable(struct ltt_kernel_session *ksession,
		struct ltt_kernel_channel *kchan)
{
	int ret;

	assert(ksession);
	assert(kchan);

	if (kchan->enabled == 0) {
		ret = kernel_enable_channel(kchan);
		if (ret < 0) {
			ret = LTTNG_ERR_KERN_CHAN_ENABLE_FAIL;
			goto error;
		}
	} else {
		ret = LTTNG_ERR_KERN_CHAN_EXIST;
		goto error;
	}

	ret = LTTNG_OK;

error:
	return ret;
}

static int channel_validate(struct lttng_channel *attr)
{
	/*
	 * The ringbuffer (both in user space and kernel) behaves badly
	 * in overwrite mode and with less than 2 subbuffers so block it
	 * right away and send back an invalid attribute error.
	 */
	if (attr->attr.overwrite && attr->attr.num_subbuf < 2) {
		return -1;
	}
	return 0;
}

/*
 * Create kernel channel of the kernel session and notify kernel thread.
 */
int channel_kernel_create(struct ltt_kernel_session *ksession,
		struct lttng_channel *attr, int kernel_pipe)
{
	int ret;
	struct lttng_channel *defattr = NULL;

	assert(ksession);

	/* Creating channel attributes if needed */
	if (attr == NULL) {
		defattr = channel_new_default_attr(LTTNG_DOMAIN_KERNEL,
				LTTNG_BUFFER_GLOBAL);
		if (defattr == NULL) {
			ret = LTTNG_ERR_FATAL;
			goto error;
		}
		attr = defattr;
	}

	if (ksession->snapshot_mode) {
		/* Force channel attribute for snapshot mode. */
		attr->attr.overwrite = 1;
		attr->attr.output = LTTNG_EVENT_MMAP;
	}

	/* Validate common channel properties. */
	if (channel_validate(attr) < 0) {
		ret = LTTNG_ERR_INVALID;
		goto error;
	}

	/* Channel not found, creating it */
	ret = kernel_create_channel(ksession, attr);
	if (ret < 0) {
		ret = LTTNG_ERR_KERN_CHAN_FAIL;
		goto error;
	}

	/* Notify kernel thread that there is a new channel */
	ret = notify_thread_pipe(kernel_pipe);
	if (ret < 0) {
		ret = LTTNG_ERR_FATAL;
		goto error;
	}

	ret = LTTNG_OK;
error:
	free(defattr);
	return ret;
}

/*
 * Enable UST channel for session and domain.
 */
int channel_ust_enable(struct ltt_ust_session *usess,
		struct ltt_ust_channel *uchan)
{
	int ret = LTTNG_OK;

	assert(usess);
	assert(uchan);

	/* If already enabled, everything is OK */
	if (uchan->enabled) {
		DBG3("Channel %s already enabled. Skipping", uchan->name);
		ret = LTTNG_ERR_UST_CHAN_EXIST;
		goto end;
	}

	DBG2("Channel %s being enabled in UST domain", uchan->name);

	/*
	 * Enable channel for UST global domain on all applications. Ignore return
	 * value here since whatever error we got, it means that the channel was
	 * not created on one or many registered applications and we can not report
	 * this to the user yet. However, at this stage, the channel was
	 * successfully created on the session daemon side so the enable-channel
	 * command is a success.
	 */
	(void) ust_app_enable_channel_glb(usess, uchan);

	uchan->enabled = 1;
	DBG2("Channel %s enabled successfully", uchan->name);

end:
	return ret;
}

/*
 * Create UST channel for session and domain.
 */
int channel_ust_create(struct ltt_ust_session *usess,
		struct lttng_channel *attr, enum lttng_buffer_type type)
{
	int ret = LTTNG_OK;
	struct ltt_ust_channel *uchan = NULL;
	struct lttng_channel *defattr = NULL;

	assert(usess);

	/* Creating channel attributes if needed */
	if (attr == NULL) {
		defattr = channel_new_default_attr(LTTNG_DOMAIN_UST, type);
		if (defattr == NULL) {
			ret = LTTNG_ERR_FATAL;
			goto error;
		}
		attr = defattr;
	}

	if (usess->snapshot_mode) {
		/* Force channel attribute for snapshot mode. */
		attr->attr.overwrite = 1;
		attr->attr.output = LTTNG_EVENT_MMAP;
	}

	/* Validate common channel properties. */
	if (channel_validate(attr) < 0) {
		ret = LTTNG_ERR_INVALID;
		goto error;
	}

	/*
	 * Validate UST buffer size and number of buffers: must both be power of 2
	 * and nonzero. We validate right here for UST, because applications will
	 * not report the error to the user (unlike kernel tracing).
	 */
	if (!attr->attr.subbuf_size ||
			(attr->attr.subbuf_size & (attr->attr.subbuf_size - 1))) {
		ret = LTTNG_ERR_INVALID;
		goto error;
	}

	/*
	 * Invalid subbuffer size if it's lower then the page size.
	 */
	if (attr->attr.subbuf_size < page_size) {
		ret = LTTNG_ERR_INVALID;
		goto error;
	}

	if (!attr->attr.num_subbuf ||
			(attr->attr.num_subbuf & (attr->attr.num_subbuf - 1))) {
		ret = LTTNG_ERR_INVALID;
		goto error;
	}

	if (attr->attr.output != LTTNG_EVENT_MMAP) {
		ret = LTTNG_ERR_NOT_SUPPORTED;
		goto error;
	}

	/*
	 * The tracefile_size should not be < to the subbuf_size, otherwise
	 * we won't be able to write the packets on disk
	 */
	if ((attr->attr.tracefile_size > 0) &&
			(attr->attr.tracefile_size < attr->attr.subbuf_size)) {
		ret = LTTNG_ERR_INVALID;
		goto error;
	}

	/* Validate buffer type. */
	switch (type) {
	case LTTNG_BUFFER_PER_PID:
		break;
	case LTTNG_BUFFER_PER_UID:
		break;
	default:
		ret = LTTNG_ERR_BUFFER_NOT_SUPPORTED;
		goto error;
	}

	/* Create UST channel */
	uchan = trace_ust_create_channel(attr, LTTNG_DOMAIN_UST);
	if (uchan == NULL) {
		ret = LTTNG_ERR_FATAL;
		goto error;
	}

	/*
	 * HACK: Set the channel's subdomain (JUL, Log4j, Python, etc.)
	 * based on the default name.
	 */
	if (!strcmp(uchan->name, DEFAULT_JUL_CHANNEL_NAME)) {
		uchan->domain = LTTNG_DOMAIN_JUL;
	} else if (!strcmp(uchan->name, DEFAULT_LOG4J_CHANNEL_NAME)) {
		uchan->domain = LTTNG_DOMAIN_LOG4J;
	} else if (!strcmp(uchan->name, DEFAULT_PYTHON_CHANNEL_NAME)) {
		uchan->domain = LTTNG_DOMAIN_PYTHON;
	}

	uchan->enabled = 1;
	if (trace_ust_is_max_id(usess->used_channel_id)) {
		ret = LTTNG_ERR_UST_CHAN_FAIL;
		goto error;
	}
	uchan->id = trace_ust_get_next_chan_id(usess);

	DBG2("Channel %s is being created for UST with buffer %d and id %" PRIu64,
			uchan->name, type, uchan->id);

	/* Flag session buffer type. */
	if (!usess->buffer_type_changed) {
		usess->buffer_type = type;
		usess->buffer_type_changed = 1;
	} else if (usess->buffer_type != type) {
		/* Buffer type was already set. Refuse to create channel. */
		ret = LTTNG_ERR_BUFFER_TYPE_MISMATCH;
		goto error_free_chan;
	}

	/* Enable channel for global domain */
	ret = ust_app_create_channel_glb(usess, uchan);
	if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
		ret = LTTNG_ERR_UST_CHAN_FAIL;
		goto error_free_chan;
	}

	/* Adding the channel to the channel hash table. */
	rcu_read_lock();
	if (strncmp(uchan->name, DEFAULT_METADATA_NAME,
				sizeof(uchan->name))) {
		lttng_ht_add_unique_str(usess->domain_global.channels, &uchan->node);
	} else {
		/*
		 * Copy channel attribute to session if this is metadata so if NO
		 * application exists we can access that data in the shadow copy during
		 * the global update of newly registered application.
		 */
		memcpy(&usess->metadata_attr, &uchan->attr,
				sizeof(usess->metadata_attr));
	}
	rcu_read_unlock();

	DBG2("Channel %s created successfully", uchan->name);

	free(defattr);
	return LTTNG_OK;

error_free_chan:
	/*
	 * No need to remove the channel from the hash table because at this point
	 * it was not added hence the direct call and no call_rcu().
	 */
	trace_ust_destroy_channel(uchan);
error:
	free(defattr);
	return ret;
}

/*
 * Disable UST channel for session and domain.
 */
int channel_ust_disable(struct ltt_ust_session *usess,
		struct ltt_ust_channel *uchan)
{
	int ret = LTTNG_OK;

	assert(usess);
	assert(uchan);

	/* Already disabled */
	if (uchan->enabled == 0) {
		DBG2("Channel UST %s already disabled", uchan->name);
		goto end;
	}

	DBG2("Channel %s being disabled in UST global domain", uchan->name);
	/* Disable channel for global domain */
	ret = ust_app_disable_channel_glb(usess, uchan);
	if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
		ret = LTTNG_ERR_UST_CHAN_DISABLE_FAIL;
		goto error;
	}

	uchan->enabled = 0;

	DBG2("Channel %s disabled successfully", uchan->name);

	return LTTNG_OK;

end:
error:
	return ret;
}
Commit	Line	Data
54d01ffb DG	1	/*
	2	* Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
	3	*
d14d33bf AM	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License, version 2 only,
	6	* as published by the Free Software Foundation.
54d01ffb	7	*
d14d33bf AM	8	* This program is distributed in the hope that it will be useful,
	9	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	10	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	11	* GNU General Public License for more details.
54d01ffb	12	*
d14d33bf AM	13	* You should have received a copy of the GNU General Public License along
	14	* with this program; if not, write to the Free Software Foundation, Inc.,
	15	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
54d01ffb DG	16	*/
54d01ffb DG	17
7885e399	18	#define _GNU_SOURCE
6c1c0768	19	#define _LGPL_SOURCE
7972aab2	20	#include <inttypes.h>
56fff090	21	#include <string.h>
54d01ffb DG	22	#include <unistd.h>
54d01ffb DG	23
990570ed DG	24	#include <common/common.h>
990570ed DG	25	#include <common/defaults.h>
db758600	26	#include <common/sessiond-comm/sessiond-comm.h>
54d01ffb DG	27
54d01ffb DG	28	#include "channel.h"
12744796	29	#include "lttng-sessiond.h"
4771f025	30	#include "kernel.h"
44d3bd01	31	#include "ust-ctl.h"
54d01ffb	32	#include "utils.h"
7885e399	33	#include "ust-app.h"
54d01ffb DG	34
	35	/*
	36	* Return allocated channel attributes.
	37	*/
0a9c6494 DG	38	struct lttng_channel *channel_new_default_attr(int dom,
0a9c6494 DG	39	enum lttng_buffer_type type)
54d01ffb DG	40	{
	41	struct lttng_channel *chan;
	42
	43	chan = zmalloc(sizeof(struct lttng_channel));
	44	if (chan == NULL) {
7885e399	45	PERROR("zmalloc channel init");
54d01ffb DG	46	goto error_alloc;
	47	}
	48
44d3bd01 DG	49	if (snprintf(chan->name, sizeof(chan->name), "%s",
44d3bd01 DG	50	DEFAULT_CHANNEL_NAME) < 0) {
7885e399	51	PERROR("snprintf default channel name");
54d01ffb DG	52	goto error;
	53	}
	54
0a9c6494	55	/* Same for all domains. */
54d01ffb	56	chan->attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
0a9c6494 DG	57	chan->attr.tracefile_size = DEFAULT_CHANNEL_TRACEFILE_SIZE;
0a9c6494 DG	58	chan->attr.tracefile_count = DEFAULT_CHANNEL_TRACEFILE_COUNT;
54d01ffb DG	59
54d01ffb DG	60	switch (dom) {
1b1c65fa	61	case LTTNG_DOMAIN_KERNEL:
0a9c6494	62	assert(type == LTTNG_BUFFER_GLOBAL);
3e230f92 SM	63	chan->attr.subbuf_size =
3e230f92 SM	64	default_get_kernel_channel_subbuf_size();
1b1c65fa MD	65	chan->attr.num_subbuf = DEFAULT_KERNEL_CHANNEL_SUBBUF_NUM;
1b1c65fa MD	66	chan->attr.output = DEFAULT_KERNEL_CHANNEL_OUTPUT;
6bb9e85f MD	67	chan->attr.switch_timer_interval = DEFAULT_KERNEL_CHANNEL_SWITCH_TIMER;
6bb9e85f MD	68	chan->attr.read_timer_interval = DEFAULT_KERNEL_CHANNEL_READ_TIMER;
ecc48a90	69	chan->attr.live_timer_interval = DEFAULT_KERNEL_CHANNEL_LIVE_TIMER;
1b1c65fa MD	70	break;
1b1c65fa MD	71	case LTTNG_DOMAIN_UST:
0a9c6494 DG	72	switch (type) {
	73	case LTTNG_BUFFER_PER_UID:
	74	chan->attr.subbuf_size = default_get_ust_uid_channel_subbuf_size();
	75	chan->attr.num_subbuf = DEFAULT_UST_UID_CHANNEL_SUBBUF_NUM;
	76	chan->attr.output = DEFAULT_UST_UID_CHANNEL_OUTPUT;
	77	chan->attr.switch_timer_interval =
	78	DEFAULT_UST_UID_CHANNEL_SWITCH_TIMER;
	79	chan->attr.read_timer_interval =
	80	DEFAULT_UST_UID_CHANNEL_READ_TIMER;
ecc48a90 JD	81	chan->attr.live_timer_interval =
ecc48a90 JD	82	DEFAULT_UST_UID_CHANNEL_LIVE_TIMER;
0a9c6494 DG	83	break;
	84	case LTTNG_BUFFER_PER_PID:
	85	default:
	86	chan->attr.subbuf_size = default_get_ust_pid_channel_subbuf_size();
	87	chan->attr.num_subbuf = DEFAULT_UST_PID_CHANNEL_SUBBUF_NUM;
	88	chan->attr.output = DEFAULT_UST_PID_CHANNEL_OUTPUT;
	89	chan->attr.switch_timer_interval =
	90	DEFAULT_UST_PID_CHANNEL_SWITCH_TIMER;
	91	chan->attr.read_timer_interval =
	92	DEFAULT_UST_PID_CHANNEL_READ_TIMER;
ecc48a90 JD	93	chan->attr.live_timer_interval =
ecc48a90 JD	94	DEFAULT_UST_UID_CHANNEL_LIVE_TIMER;
0a9c6494 DG	95	break;
0a9c6494 DG	96	}
1b1c65fa MD	97	break;
	98	default:
	99	goto error; /* Not implemented */
54d01ffb DG	100	}
	101
	102	return chan;
	103
	104	error:
	105	free(chan);
	106	error_alloc:
	107	return NULL;
	108	}
	109
	110	/*
	111	* Disable kernel channel of the kernel session.
	112	*/
	113	int channel_kernel_disable(struct ltt_kernel_session *ksession,
	114	char *channel_name)
	115	{
	116	int ret;
	117	struct ltt_kernel_channel *kchan;
	118
0525e9ae DG	119	assert(ksession);
	120	assert(channel_name);
	121
54d01ffb DG	122	kchan = trace_kernel_get_channel_by_name(channel_name, ksession);
54d01ffb DG	123	if (kchan == NULL) {
f73fabfd	124	ret = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
54d01ffb	125	goto error;
0525e9ae DG	126	}
	127
	128	/* Only if channel is enabled disable it. */
	129	if (kchan->enabled == 1) {
54d01ffb	130	ret = kernel_disable_channel(kchan);
7885e399	131	if (ret < 0 && ret != -EEXIST) {
f73fabfd	132	ret = LTTNG_ERR_KERN_CHAN_DISABLE_FAIL;
54d01ffb DG	133	goto error;
	134	}
	135	}
	136
f73fabfd	137	ret = LTTNG_OK;
54d01ffb DG	138
	139	error:
	140	return ret;
	141	}
	142
	143	/*
	144	* Enable kernel channel of the kernel session.
	145	*/
	146	int channel_kernel_enable(struct ltt_kernel_session *ksession,
	147	struct ltt_kernel_channel *kchan)
	148	{
	149	int ret;
	150
0525e9ae DG	151	assert(ksession);
	152	assert(kchan);
	153
54d01ffb DG	154	if (kchan->enabled == 0) {
	155	ret = kernel_enable_channel(kchan);
	156	if (ret < 0) {
f73fabfd	157	ret = LTTNG_ERR_KERN_CHAN_ENABLE_FAIL;
54d01ffb DG	158	goto error;
54d01ffb DG	159	}
42224349	160	} else {
f73fabfd	161	ret = LTTNG_ERR_KERN_CHAN_EXIST;
42224349	162	goto error;
54d01ffb DG	163	}
54d01ffb DG	164
f73fabfd	165	ret = LTTNG_OK;
54d01ffb DG	166
	167	error:
	168	return ret;
	169	}
	170
a297c109 MD	171	static int channel_validate(struct lttng_channel *attr)
	172	{
	173	/*
	174	* The ringbuffer (both in user space and kernel) behaves badly
	175	* in overwrite mode and with less than 2 subbuffers so block it
	176	* right away and send back an invalid attribute error.
	177	*/
	178	if (attr->attr.overwrite && attr->attr.num_subbuf < 2) {
	179	return -1;
	180	}
	181	return 0;
	182	}
	183
54d01ffb DG	184	/*
	185	* Create kernel channel of the kernel session and notify kernel thread.
	186	*/
	187	int channel_kernel_create(struct ltt_kernel_session *ksession,
ff4d74e6	188	struct lttng_channel *attr, int kernel_pipe)
54d01ffb DG	189	{
54d01ffb DG	190	int ret;
ff4d74e6	191	struct lttng_channel *defattr = NULL;
54d01ffb	192
0525e9ae DG	193	assert(ksession);
0525e9ae DG	194
54d01ffb DG	195	/* Creating channel attributes if needed */
54d01ffb DG	196	if (attr == NULL) {
0a9c6494 DG	197	defattr = channel_new_default_attr(LTTNG_DOMAIN_KERNEL,
0a9c6494 DG	198	LTTNG_BUFFER_GLOBAL);
ff4d74e6	199	if (defattr == NULL) {
f73fabfd	200	ret = LTTNG_ERR_FATAL;
54d01ffb DG	201	goto error;
54d01ffb DG	202	}
ff4d74e6	203	attr = defattr;
54d01ffb DG	204	}
54d01ffb DG	205
27babd3a DG	206	if (ksession->snapshot_mode) {
	207	/* Force channel attribute for snapshot mode. */
	208	attr->attr.overwrite = 1;
	209	attr->attr.output = LTTNG_EVENT_MMAP;
	210	}
	211
a297c109 MD	212	/* Validate common channel properties. */
	213	if (channel_validate(attr) < 0) {
	214	ret = LTTNG_ERR_INVALID;
	215	goto error;
	216	}
	217
54d01ffb	218	/* Channel not found, creating it */
fdd9eb17	219	ret = kernel_create_channel(ksession, attr);
54d01ffb	220	if (ret < 0) {
f73fabfd	221	ret = LTTNG_ERR_KERN_CHAN_FAIL;
54d01ffb DG	222	goto error;
	223	}
	224
	225	/* Notify kernel thread that there is a new channel */
	226	ret = notify_thread_pipe(kernel_pipe);
	227	if (ret < 0) {
f73fabfd	228	ret = LTTNG_ERR_FATAL;
54d01ffb DG	229	goto error;
	230	}
	231
f73fabfd	232	ret = LTTNG_OK;
54d01ffb	233	error:
ff4d74e6	234	free(defattr);
54d01ffb DG	235	return ret;
54d01ffb DG	236	}
7885e399 DG	237
	238	/*
	239	* Enable UST channel for session and domain.
	240	*/
7972aab2	241	int channel_ust_enable(struct ltt_ust_session *usess,
7885e399 DG	242	struct ltt_ust_channel *uchan)
7885e399 DG	243	{
f73fabfd	244	int ret = LTTNG_OK;
7885e399	245
0525e9ae DG	246	assert(usess);
	247	assert(uchan);
	248
7885e399 DG	249	/* If already enabled, everything is OK */
	250	if (uchan->enabled) {
	251	DBG3("Channel %s already enabled. Skipping", uchan->name);
f73fabfd	252	ret = LTTNG_ERR_UST_CHAN_EXIST;
7885e399 DG	253	goto end;
	254	}
	255
7972aab2 DG	256	DBG2("Channel %s being enabled in UST domain", uchan->name);
	257
	258	/*
	259	* Enable channel for UST global domain on all applications. Ignore return
	260	* value here since whatever error we got, it means that the channel was
	261	* not created on one or many registered applications and we can not report
	262	* this to the user yet. However, at this stage, the channel was
	263	* successfully created on the session daemon side so the enable-channel
	264	* command is a success.
	265	*/
d54b4440	266	(void) ust_app_enable_channel_glb(usess, uchan);
7885e399	267
7885e399 DG	268	uchan->enabled = 1;
	269	DBG2("Channel %s enabled successfully", uchan->name);
	270
	271	end:
7885e399 DG	272	return ret;
	273	}
	274
	275	/*
	276	* Create UST channel for session and domain.
	277	*/
7972aab2 DG	278	int channel_ust_create(struct ltt_ust_session *usess,
7972aab2 DG	279	struct lttng_channel *attr, enum lttng_buffer_type type)
7885e399	280	{
f73fabfd	281	int ret = LTTNG_OK;
7885e399 DG	282	struct ltt_ust_channel *uchan = NULL;
	283	struct lttng_channel *defattr = NULL;
	284
0525e9ae DG	285	assert(usess);
0525e9ae DG	286
7885e399 DG	287	/* Creating channel attributes if needed */
7885e399 DG	288	if (attr == NULL) {
0a9c6494	289	defattr = channel_new_default_attr(LTTNG_DOMAIN_UST, type);
7885e399	290	if (defattr == NULL) {
f73fabfd	291	ret = LTTNG_ERR_FATAL;
7885e399 DG	292	goto error;
	293	}
	294	attr = defattr;
	295	}
	296
27babd3a DG	297	if (usess->snapshot_mode) {
	298	/* Force channel attribute for snapshot mode. */
	299	attr->attr.overwrite = 1;
	300	attr->attr.output = LTTNG_EVENT_MMAP;
	301	}
	302
a297c109 MD	303	/* Validate common channel properties. */
	304	if (channel_validate(attr) < 0) {
	305	ret = LTTNG_ERR_INVALID;
	306	goto error;
	307	}
	308
b024d072	309	/*
0525e9ae DG	310	* Validate UST buffer size and number of buffers: must both be power of 2
	311	* and nonzero. We validate right here for UST, because applications will
	312	* not report the error to the user (unlike kernel tracing).
b024d072	313	*/
0525e9ae DG	314	if (!attr->attr.subbuf_size \|\|
0525e9ae DG	315	(attr->attr.subbuf_size & (attr->attr.subbuf_size - 1))) {
f73fabfd	316	ret = LTTNG_ERR_INVALID;
b024d072 MD	317	goto error;
b024d072 MD	318	}
0525e9ae	319
12744796 DG	320	/*
	321	* Invalid subbuffer size if it's lower then the page size.
	322	*/
	323	if (attr->attr.subbuf_size < page_size) {
	324	ret = LTTNG_ERR_INVALID;
	325	goto error;
	326	}
	327
0525e9ae DG	328	if (!attr->attr.num_subbuf \|\|
0525e9ae DG	329	(attr->attr.num_subbuf & (attr->attr.num_subbuf - 1))) {
f73fabfd	330	ret = LTTNG_ERR_INVALID;
b024d072 MD	331	goto error;
	332	}
	333
a79d84dd DG	334	if (attr->attr.output != LTTNG_EVENT_MMAP) {
	335	ret = LTTNG_ERR_NOT_SUPPORTED;
	336	goto error;
	337	}
	338
1624d5b7 JD	339	/*
	340	* The tracefile_size should not be < to the subbuf_size, otherwise
	341	* we won't be able to write the packets on disk
	342	*/
	343	if ((attr->attr.tracefile_size > 0) &&
	344	(attr->attr.tracefile_size < attr->attr.subbuf_size)) {
	345	ret = LTTNG_ERR_INVALID;
	346	goto error;
	347	}
	348
2e8269f7 DG	349	/* Validate buffer type. */
	350	switch (type) {
	351	case LTTNG_BUFFER_PER_PID:
0a9c6494	352	break;
2e8269f7 DG	353	case LTTNG_BUFFER_PER_UID:
	354	break;
	355	default:
	356	ret = LTTNG_ERR_BUFFER_NOT_SUPPORTED;
	357	goto error;
	358	}
	359
7885e399	360	/* Create UST channel */
0a3fca4d	361	uchan = trace_ust_create_channel(attr, LTTNG_DOMAIN_UST);
7885e399	362	if (uchan == NULL) {
f73fabfd	363	ret = LTTNG_ERR_FATAL;
7885e399 DG	364	goto error;
7885e399 DG	365	}
0a3fca4d JG	366
	367	/*
	368	* HACK: Set the channel's subdomain (JUL, Log4j, Python, etc.)
	369	* based on the default name.
	370	*/
	371	if (!strcmp(uchan->name, DEFAULT_JUL_CHANNEL_NAME)) {
	372	uchan->domain = LTTNG_DOMAIN_JUL;
	373	} else if (!strcmp(uchan->name, DEFAULT_LOG4J_CHANNEL_NAME)) {
	374	uchan->domain = LTTNG_DOMAIN_LOG4J;
	375	} else if (!strcmp(uchan->name, DEFAULT_PYTHON_CHANNEL_NAME)) {
	376	uchan->domain = LTTNG_DOMAIN_PYTHON;
	377	}
	378
58f3ca76	379	uchan->enabled = 1;
7972aab2 DG	380	if (trace_ust_is_max_id(usess->used_channel_id)) {
	381	ret = LTTNG_ERR_UST_CHAN_FAIL;
	382	goto error;
	383	}
	384	uchan->id = trace_ust_get_next_chan_id(usess);
	385
	386	DBG2("Channel %s is being created for UST with buffer %d and id %" PRIu64,
	387	uchan->name, type, uchan->id);
	388
	389	/* Flag session buffer type. */
	390	if (!usess->buffer_type_changed) {
	391	usess->buffer_type = type;
	392	usess->buffer_type_changed = 1;
	393	} else if (usess->buffer_type != type) {
	394	/* Buffer type was already set. Refuse to create channel. */
	395	ret = LTTNG_ERR_BUFFER_TYPE_MISMATCH;
7885e399 DG	396	goto error_free_chan;
	397	}
	398
7972aab2 DG	399	/* Enable channel for global domain */
7972aab2 DG	400	ret = ust_app_create_channel_glb(usess, uchan);
49c336c1	401	if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
f73fabfd	402	ret = LTTNG_ERR_UST_CHAN_FAIL;
7885e399 DG	403	goto error_free_chan;
	404	}
	405
fc34caaa DG	406	/* Adding the channel to the channel hash table. */
fc34caaa DG	407	rcu_read_lock();
ad7a9107 DG	408	if (strncmp(uchan->name, DEFAULT_METADATA_NAME,
	409	sizeof(uchan->name))) {
	410	lttng_ht_add_unique_str(usess->domain_global.channels, &uchan->node);
84ad93e8 DG	411	} else {
	412	/*
	413	* Copy channel attribute to session if this is metadata so if NO
	414	* application exists we can access that data in the shadow copy during
	415	* the global update of newly registered application.
	416	*/
	417	memcpy(&usess->metadata_attr, &uchan->attr,
	418	sizeof(usess->metadata_attr));
ad7a9107	419	}
fc34caaa DG	420	rcu_read_unlock();
fc34caaa DG	421
7885e399 DG	422	DBG2("Channel %s created successfully", uchan->name);
	423
	424	free(defattr);
f73fabfd	425	return LTTNG_OK;
7885e399 DG	426
7885e399 DG	427	error_free_chan:
24d1723f DG	428	/*
	429	* No need to remove the channel from the hash table because at this point
	430	* it was not added hence the direct call and no call_rcu().
	431	*/
7885e399 DG	432	trace_ust_destroy_channel(uchan);
	433	error:
	434	free(defattr);
	435	return ret;
	436	}
	437
	438	/*
	439	* Disable UST channel for session and domain.
	440	*/
7972aab2	441	int channel_ust_disable(struct ltt_ust_session *usess,
7885e399 DG	442	struct ltt_ust_channel *uchan)
7885e399 DG	443	{
f73fabfd	444	int ret = LTTNG_OK;
7885e399	445
0525e9ae DG	446	assert(usess);
	447	assert(uchan);
	448
7885e399 DG	449	/* Already disabled */
	450	if (uchan->enabled == 0) {
	451	DBG2("Channel UST %s already disabled", uchan->name);
	452	goto end;
	453	}
	454
7972aab2 DG	455	DBG2("Channel %s being disabled in UST global domain", uchan->name);
	456	/* Disable channel for global domain */
	457	ret = ust_app_disable_channel_glb(usess, uchan);
49c336c1	458	if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
f73fabfd	459	ret = LTTNG_ERR_UST_CHAN_DISABLE_FAIL;
7885e399 DG	460	goto error;
	461	}
	462
	463	uchan->enabled = 0;
	464
	465	DBG2("Channel %s disabled successfully", uchan->name);
	466
f73fabfd	467	return LTTNG_OK;
7885e399 DG	468
	469	end:
	470	error:
	471	return ret;
	472	}