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

/*
 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
 * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@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 <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"
#include "agent.h"

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

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

	/* 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_JUL:
		channel_name = DEFAULT_JUL_CHANNEL_NAME;
		goto common_ust;
	case LTTNG_DOMAIN_LOG4J:
		channel_name = DEFAULT_LOG4J_CHANNEL_NAME;
		goto common_ust;
	case LTTNG_DOMAIN_PYTHON:
		channel_name = DEFAULT_PYTHON_CHANNEL_NAME;
		goto common_ust;
	case LTTNG_DOMAIN_UST:
common_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 */
	}

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

	/*
	 * Set the overwrite mode for this channel based on the session
	 * type unless the client explicitly overrides the channel mode.
	 */
	if (attr->attr.overwrite == DEFAULT_CHANNEL_OVERWRITE) {
		attr->attr.overwrite = !!ksession->snapshot_mode;
	}

	/* Enforce mmap output for snapshot sessions. */
	if (ksession->snapshot_mode) {
		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;
	enum lttng_domain_type domain = LTTNG_DOMAIN_UST;
	bool chan_published = false;

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

	/*
	 * Set the overwrite mode for this channel based on the session
	 * type unless the client explicitly overrides the channel mode.
	 */
	if (attr->attr.overwrite == DEFAULT_CHANNEL_OVERWRITE) {
		attr->attr.overwrite = !!usess->snapshot_mode;
	}

	/* Enforce mmap output for snapshot sessions. */
	if (usess->snapshot_mode) {
		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, domain);
	if (uchan == NULL) {
		ret = LTTNG_ERR_FATAL;
		goto error;
	}

	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);
		chan_published = true;
	} 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);
	if (domain != LTTNG_DOMAIN_UST) {
		struct agent *agt = trace_ust_find_agent(usess, domain);

		if (!agt) {
			agt = agent_create(domain);
			if (!agt) {
				ret = LTTNG_ERR_NOMEM;
				goto error_remove_chan;
			}
			agent_add(agt, usess->agents);
		}
	}

	free(defattr);
	return LTTNG_OK;

error_remove_chan:
	if (chan_published) {
		trace_ust_delete_channel(usess->domain_global.channels, uchan);
	}
error_free_chan:
	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	/*
54d01ffb DG	2	* Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
bdf64013	3	* Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
54d01ffb	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.
54d01ffb	8	*
d14d33bf AM	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.
54d01ffb	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.
54d01ffb DG	17	*/
54d01ffb DG	18
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"
b63d638b	34	#include "agent.h"
54d01ffb DG	35
	36	/*
	37	* Return allocated channel attributes.
	38	*/
0a9c6494 DG	39	struct lttng_channel *channel_new_default_attr(int dom,
0a9c6494 DG	40	enum lttng_buffer_type type)
54d01ffb DG	41	{
54d01ffb DG	42	struct lttng_channel *chan;
bdf64013	43	const char *channel_name = DEFAULT_CHANNEL_NAME;
54d01ffb DG	44
	45	chan = zmalloc(sizeof(struct lttng_channel));
	46	if (chan == NULL) {
7885e399	47	PERROR("zmalloc channel init");
54d01ffb DG	48	goto error_alloc;
	49	}
	50
0a9c6494	51	/* Same for all domains. */
54d01ffb	52	chan->attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
0a9c6494 DG	53	chan->attr.tracefile_size = DEFAULT_CHANNEL_TRACEFILE_SIZE;
0a9c6494 DG	54	chan->attr.tracefile_count = DEFAULT_CHANNEL_TRACEFILE_COUNT;
54d01ffb DG	55
54d01ffb DG	56	switch (dom) {
1b1c65fa	57	case LTTNG_DOMAIN_KERNEL:
0a9c6494	58	assert(type == LTTNG_BUFFER_GLOBAL);
3e230f92 SM	59	chan->attr.subbuf_size =
3e230f92 SM	60	default_get_kernel_channel_subbuf_size();
1b1c65fa MD	61	chan->attr.num_subbuf = DEFAULT_KERNEL_CHANNEL_SUBBUF_NUM;
1b1c65fa MD	62	chan->attr.output = DEFAULT_KERNEL_CHANNEL_OUTPUT;
6bb9e85f MD	63	chan->attr.switch_timer_interval = DEFAULT_KERNEL_CHANNEL_SWITCH_TIMER;
6bb9e85f MD	64	chan->attr.read_timer_interval = DEFAULT_KERNEL_CHANNEL_READ_TIMER;
ecc48a90	65	chan->attr.live_timer_interval = DEFAULT_KERNEL_CHANNEL_LIVE_TIMER;
1b1c65fa	66	break;
bdf64013 JG	67	case LTTNG_DOMAIN_JUL:
	68	channel_name = DEFAULT_JUL_CHANNEL_NAME;
	69	goto common_ust;
	70	case LTTNG_DOMAIN_LOG4J:
	71	channel_name = DEFAULT_LOG4J_CHANNEL_NAME;
	72	goto common_ust;
	73	case LTTNG_DOMAIN_PYTHON:
	74	channel_name = DEFAULT_PYTHON_CHANNEL_NAME;
	75	goto common_ust;
1b1c65fa	76	case LTTNG_DOMAIN_UST:
bdf64013	77	common_ust:
0a9c6494 DG	78	switch (type) {
	79	case LTTNG_BUFFER_PER_UID:
	80	chan->attr.subbuf_size = default_get_ust_uid_channel_subbuf_size();
	81	chan->attr.num_subbuf = DEFAULT_UST_UID_CHANNEL_SUBBUF_NUM;
	82	chan->attr.output = DEFAULT_UST_UID_CHANNEL_OUTPUT;
	83	chan->attr.switch_timer_interval =
	84	DEFAULT_UST_UID_CHANNEL_SWITCH_TIMER;
	85	chan->attr.read_timer_interval =
	86	DEFAULT_UST_UID_CHANNEL_READ_TIMER;
ecc48a90 JD	87	chan->attr.live_timer_interval =
ecc48a90 JD	88	DEFAULT_UST_UID_CHANNEL_LIVE_TIMER;
0a9c6494 DG	89	break;
	90	case LTTNG_BUFFER_PER_PID:
	91	default:
	92	chan->attr.subbuf_size = default_get_ust_pid_channel_subbuf_size();
	93	chan->attr.num_subbuf = DEFAULT_UST_PID_CHANNEL_SUBBUF_NUM;
	94	chan->attr.output = DEFAULT_UST_PID_CHANNEL_OUTPUT;
	95	chan->attr.switch_timer_interval =
	96	DEFAULT_UST_PID_CHANNEL_SWITCH_TIMER;
	97	chan->attr.read_timer_interval =
	98	DEFAULT_UST_PID_CHANNEL_READ_TIMER;
ecc48a90 JD	99	chan->attr.live_timer_interval =
ecc48a90 JD	100	DEFAULT_UST_UID_CHANNEL_LIVE_TIMER;
0a9c6494 DG	101	break;
0a9c6494 DG	102	}
1b1c65fa MD	103	break;
	104	default:
	105	goto error; /* Not implemented */
54d01ffb DG	106	}
54d01ffb DG	107
bdf64013 JG	108	if (snprintf(chan->name, sizeof(chan->name), "%s",
	109	channel_name) < 0) {
	110	PERROR("snprintf default channel name");
	111	goto error;
	112	}
54d01ffb DG	113	return chan;
	114
	115	error:
	116	free(chan);
	117	error_alloc:
	118	return NULL;
	119	}
	120
	121	/*
	122	* Disable kernel channel of the kernel session.
	123	*/
	124	int channel_kernel_disable(struct ltt_kernel_session *ksession,
	125	char *channel_name)
	126	{
	127	int ret;
	128	struct ltt_kernel_channel *kchan;
	129
0525e9ae DG	130	assert(ksession);
	131	assert(channel_name);
	132
54d01ffb DG	133	kchan = trace_kernel_get_channel_by_name(channel_name, ksession);
54d01ffb DG	134	if (kchan == NULL) {
f73fabfd	135	ret = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
54d01ffb	136	goto error;
0525e9ae DG	137	}
	138
	139	/* Only if channel is enabled disable it. */
	140	if (kchan->enabled == 1) {
54d01ffb	141	ret = kernel_disable_channel(kchan);
7885e399	142	if (ret < 0 && ret != -EEXIST) {
f73fabfd	143	ret = LTTNG_ERR_KERN_CHAN_DISABLE_FAIL;
54d01ffb DG	144	goto error;
	145	}
	146	}
	147
f73fabfd	148	ret = LTTNG_OK;
54d01ffb DG	149
	150	error:
	151	return ret;
	152	}
	153
	154	/*
	155	* Enable kernel channel of the kernel session.
	156	*/
	157	int channel_kernel_enable(struct ltt_kernel_session *ksession,
	158	struct ltt_kernel_channel *kchan)
	159	{
	160	int ret;
	161
0525e9ae DG	162	assert(ksession);
	163	assert(kchan);
	164
54d01ffb DG	165	if (kchan->enabled == 0) {
	166	ret = kernel_enable_channel(kchan);
	167	if (ret < 0) {
f73fabfd	168	ret = LTTNG_ERR_KERN_CHAN_ENABLE_FAIL;
54d01ffb DG	169	goto error;
54d01ffb DG	170	}
42224349	171	} else {
f73fabfd	172	ret = LTTNG_ERR_KERN_CHAN_EXIST;
42224349	173	goto error;
54d01ffb DG	174	}
54d01ffb DG	175
f73fabfd	176	ret = LTTNG_OK;
54d01ffb DG	177
	178	error:
	179	return ret;
	180	}
	181
da9d9d9c MD	182	static int channel_validate(struct lttng_channel *attr)
	183	{
	184	/*
	185	* The ringbuffer (both in user space and kernel) behaves badly
	186	* in overwrite mode and with less than 2 subbuffers so block it
	187	* right away and send back an invalid attribute error.
	188	*/
	189	if (attr->attr.overwrite && attr->attr.num_subbuf < 2) {
	190	return -1;
	191	}
	192	return 0;
	193	}
	194
54d01ffb DG	195	/*
	196	* Create kernel channel of the kernel session and notify kernel thread.
	197	*/
	198	int channel_kernel_create(struct ltt_kernel_session *ksession,
ff4d74e6	199	struct lttng_channel *attr, int kernel_pipe)
54d01ffb DG	200	{
54d01ffb DG	201	int ret;
ff4d74e6	202	struct lttng_channel *defattr = NULL;
54d01ffb	203
0525e9ae DG	204	assert(ksession);
0525e9ae DG	205
54d01ffb DG	206	/* Creating channel attributes if needed */
54d01ffb DG	207	if (attr == NULL) {
0a9c6494 DG	208	defattr = channel_new_default_attr(LTTNG_DOMAIN_KERNEL,
0a9c6494 DG	209	LTTNG_BUFFER_GLOBAL);
ff4d74e6	210	if (defattr == NULL) {
f73fabfd	211	ret = LTTNG_ERR_FATAL;
54d01ffb DG	212	goto error;
54d01ffb DG	213	}
ff4d74e6	214	attr = defattr;
54d01ffb DG	215	}
54d01ffb DG	216
8d5841ea MD	217	/*
	218	* Set the overwrite mode for this channel based on the session
	219	* type unless the client explicitly overrides the channel mode.
	220	*/
	221	if (attr->attr.overwrite == DEFAULT_CHANNEL_OVERWRITE) {
	222	attr->attr.overwrite = !!ksession->snapshot_mode;
	223	}
	224
	225	/* Enforce mmap output for snapshot sessions. */
27babd3a	226	if (ksession->snapshot_mode) {
27babd3a DG	227	attr->attr.output = LTTNG_EVENT_MMAP;
	228	}
	229
da9d9d9c MD	230	/* Validate common channel properties. */
	231	if (channel_validate(attr) < 0) {
	232	ret = LTTNG_ERR_INVALID;
	233	goto error;
	234	}
	235
54d01ffb	236	/* Channel not found, creating it */
fdd9eb17	237	ret = kernel_create_channel(ksession, attr);
54d01ffb	238	if (ret < 0) {
f73fabfd	239	ret = LTTNG_ERR_KERN_CHAN_FAIL;
54d01ffb DG	240	goto error;
	241	}
	242
	243	/* Notify kernel thread that there is a new channel */
	244	ret = notify_thread_pipe(kernel_pipe);
	245	if (ret < 0) {
f73fabfd	246	ret = LTTNG_ERR_FATAL;
54d01ffb DG	247	goto error;
	248	}
	249
f73fabfd	250	ret = LTTNG_OK;
54d01ffb	251	error:
ff4d74e6	252	free(defattr);
54d01ffb DG	253	return ret;
54d01ffb DG	254	}
7885e399 DG	255
	256	/*
	257	* Enable UST channel for session and domain.
	258	*/
7972aab2	259	int channel_ust_enable(struct ltt_ust_session *usess,
7885e399 DG	260	struct ltt_ust_channel *uchan)
7885e399 DG	261	{
f73fabfd	262	int ret = LTTNG_OK;
7885e399	263
0525e9ae DG	264	assert(usess);
	265	assert(uchan);
	266
7885e399 DG	267	/* If already enabled, everything is OK */
	268	if (uchan->enabled) {
	269	DBG3("Channel %s already enabled. Skipping", uchan->name);
f73fabfd	270	ret = LTTNG_ERR_UST_CHAN_EXIST;
7885e399 DG	271	goto end;
	272	}
	273
7972aab2 DG	274	DBG2("Channel %s being enabled in UST domain", uchan->name);
	275
	276	/*
	277	* Enable channel for UST global domain on all applications. Ignore return
	278	* value here since whatever error we got, it means that the channel was
	279	* not created on one or many registered applications and we can not report
	280	* this to the user yet. However, at this stage, the channel was
	281	* successfully created on the session daemon side so the enable-channel
	282	* command is a success.
	283	*/
d54b4440	284	(void) ust_app_enable_channel_glb(usess, uchan);
7885e399	285
7885e399 DG	286	uchan->enabled = 1;
	287	DBG2("Channel %s enabled successfully", uchan->name);
	288
	289	end:
7885e399 DG	290	return ret;
	291	}
	292
	293	/*
	294	* Create UST channel for session and domain.
	295	*/
7972aab2 DG	296	int channel_ust_create(struct ltt_ust_session *usess,
7972aab2 DG	297	struct lttng_channel *attr, enum lttng_buffer_type type)
7885e399	298	{
f73fabfd	299	int ret = LTTNG_OK;
7885e399 DG	300	struct ltt_ust_channel *uchan = NULL;
7885e399 DG	301	struct lttng_channel *defattr = NULL;
b63d638b	302	enum lttng_domain_type domain = LTTNG_DOMAIN_UST;
5d9fd660	303	bool chan_published = false;
7885e399	304
0525e9ae DG	305	assert(usess);
0525e9ae DG	306
7885e399 DG	307	/* Creating channel attributes if needed */
7885e399 DG	308	if (attr == NULL) {
0a9c6494	309	defattr = channel_new_default_attr(LTTNG_DOMAIN_UST, type);
7885e399	310	if (defattr == NULL) {
f73fabfd	311	ret = LTTNG_ERR_FATAL;
7885e399 DG	312	goto error;
	313	}
	314	attr = defattr;
b63d638b JG	315	} else {
	316	/*
	317	* HACK: Set the channel's subdomain (JUL, Log4j, Python, etc.)
	318	* based on the default name.
	319	*/
	320	if (!strcmp(attr->name, DEFAULT_JUL_CHANNEL_NAME)) {
	321	domain = LTTNG_DOMAIN_JUL;
	322	} else if (!strcmp(attr->name, DEFAULT_LOG4J_CHANNEL_NAME)) {
	323	domain = LTTNG_DOMAIN_LOG4J;
	324	} else if (!strcmp(attr->name, DEFAULT_PYTHON_CHANNEL_NAME)) {
	325	domain = LTTNG_DOMAIN_PYTHON;
	326	}
7885e399 DG	327	}
7885e399 DG	328
8d5841ea MD	329	/*
	330	* Set the overwrite mode for this channel based on the session
	331	* type unless the client explicitly overrides the channel mode.
	332	*/
	333	if (attr->attr.overwrite == DEFAULT_CHANNEL_OVERWRITE) {
	334	attr->attr.overwrite = !!usess->snapshot_mode;
	335	}
	336
	337	/* Enforce mmap output for snapshot sessions. */
27babd3a	338	if (usess->snapshot_mode) {
27babd3a DG	339	attr->attr.output = LTTNG_EVENT_MMAP;
	340	}
	341
da9d9d9c MD	342	/* Validate common channel properties. */
	343	if (channel_validate(attr) < 0) {
	344	ret = LTTNG_ERR_INVALID;
	345	goto error;
	346	}
	347
b024d072	348	/*
0525e9ae DG	349	* Validate UST buffer size and number of buffers: must both be power of 2
	350	* and nonzero. We validate right here for UST, because applications will
	351	* not report the error to the user (unlike kernel tracing).
b024d072	352	*/
0525e9ae DG	353	if (!attr->attr.subbuf_size \|\|
0525e9ae DG	354	(attr->attr.subbuf_size & (attr->attr.subbuf_size - 1))) {
f73fabfd	355	ret = LTTNG_ERR_INVALID;
b024d072 MD	356	goto error;
b024d072 MD	357	}
0525e9ae	358
12744796 DG	359	/*
	360	* Invalid subbuffer size if it's lower then the page size.
	361	*/
	362	if (attr->attr.subbuf_size < page_size) {
	363	ret = LTTNG_ERR_INVALID;
	364	goto error;
	365	}
	366
0525e9ae DG	367	if (!attr->attr.num_subbuf \|\|
0525e9ae DG	368	(attr->attr.num_subbuf & (attr->attr.num_subbuf - 1))) {
f73fabfd	369	ret = LTTNG_ERR_INVALID;
b024d072 MD	370	goto error;
	371	}
	372
a79d84dd DG	373	if (attr->attr.output != LTTNG_EVENT_MMAP) {
	374	ret = LTTNG_ERR_NOT_SUPPORTED;
	375	goto error;
	376	}
	377
1624d5b7 JD	378	/*
	379	* The tracefile_size should not be < to the subbuf_size, otherwise
	380	* we won't be able to write the packets on disk
	381	*/
	382	if ((attr->attr.tracefile_size > 0) &&
	383	(attr->attr.tracefile_size < attr->attr.subbuf_size)) {
	384	ret = LTTNG_ERR_INVALID;
	385	goto error;
	386	}
	387
2e8269f7 DG	388	/* Validate buffer type. */
	389	switch (type) {
	390	case LTTNG_BUFFER_PER_PID:
0a9c6494	391	break;
2e8269f7 DG	392	case LTTNG_BUFFER_PER_UID:
	393	break;
	394	default:
	395	ret = LTTNG_ERR_BUFFER_NOT_SUPPORTED;
	396	goto error;
	397	}
	398
7885e399	399	/* Create UST channel */
b63d638b	400	uchan = trace_ust_create_channel(attr, domain);
7885e399	401	if (uchan == NULL) {
f73fabfd	402	ret = LTTNG_ERR_FATAL;
7885e399 DG	403	goto error;
7885e399 DG	404	}
51755dc8	405
58f3ca76	406	uchan->enabled = 1;
7972aab2 DG	407	if (trace_ust_is_max_id(usess->used_channel_id)) {
	408	ret = LTTNG_ERR_UST_CHAN_FAIL;
	409	goto error;
	410	}
	411	uchan->id = trace_ust_get_next_chan_id(usess);
	412
	413	DBG2("Channel %s is being created for UST with buffer %d and id %" PRIu64,
	414	uchan->name, type, uchan->id);
	415
	416	/* Flag session buffer type. */
	417	if (!usess->buffer_type_changed) {
	418	usess->buffer_type = type;
	419	usess->buffer_type_changed = 1;
	420	} else if (usess->buffer_type != type) {
	421	/* Buffer type was already set. Refuse to create channel. */
	422	ret = LTTNG_ERR_BUFFER_TYPE_MISMATCH;
7885e399 DG	423	goto error_free_chan;
	424	}
	425
7972aab2 DG	426	/* Enable channel for global domain */
7972aab2 DG	427	ret = ust_app_create_channel_glb(usess, uchan);
49c336c1	428	if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
f73fabfd	429	ret = LTTNG_ERR_UST_CHAN_FAIL;
7885e399 DG	430	goto error_free_chan;
	431	}
	432
fc34caaa DG	433	/* Adding the channel to the channel hash table. */
fc34caaa DG	434	rcu_read_lock();
ad7a9107 DG	435	if (strncmp(uchan->name, DEFAULT_METADATA_NAME,
	436	sizeof(uchan->name))) {
	437	lttng_ht_add_unique_str(usess->domain_global.channels, &uchan->node);
5d9fd660	438	chan_published = true;
84ad93e8 DG	439	} else {
	440	/*
	441	* Copy channel attribute to session if this is metadata so if NO
	442	* application exists we can access that data in the shadow copy during
	443	* the global update of newly registered application.
	444	*/
	445	memcpy(&usess->metadata_attr, &uchan->attr,
	446	sizeof(usess->metadata_attr));
ad7a9107	447	}
fc34caaa DG	448	rcu_read_unlock();
fc34caaa DG	449
7885e399	450	DBG2("Channel %s created successfully", uchan->name);
b63d638b JG	451	if (domain != LTTNG_DOMAIN_UST) {
	452	struct agent *agt = trace_ust_find_agent(usess, domain);
	453
	454	if (!agt) {
	455	agt = agent_create(domain);
	456	if (!agt) {
	457	ret = LTTNG_ERR_NOMEM;
5d9fd660	458	goto error_remove_chan;
b63d638b JG	459	}
	460	agent_add(agt, usess->agents);
	461	}
	462	}
7885e399 DG	463
7885e399 DG	464	free(defattr);
f73fabfd	465	return LTTNG_OK;
7885e399	466
5d9fd660 MD	467	error_remove_chan:
	468	if (chan_published) {
	469	trace_ust_delete_channel(usess->domain_global.channels, uchan);
	470	}
7885e399 DG	471	error_free_chan:
	472	trace_ust_destroy_channel(uchan);
	473	error:
	474	free(defattr);
	475	return ret;
	476	}
	477
	478	/*
	479	* Disable UST channel for session and domain.
	480	*/
7972aab2	481	int channel_ust_disable(struct ltt_ust_session *usess,
7885e399 DG	482	struct ltt_ust_channel *uchan)
7885e399 DG	483	{
f73fabfd	484	int ret = LTTNG_OK;
7885e399	485
0525e9ae DG	486	assert(usess);
	487	assert(uchan);
	488
7885e399 DG	489	/* Already disabled */
	490	if (uchan->enabled == 0) {
	491	DBG2("Channel UST %s already disabled", uchan->name);
	492	goto end;
	493	}
	494
7972aab2 DG	495	DBG2("Channel %s being disabled in UST global domain", uchan->name);
	496	/* Disable channel for global domain */
	497	ret = ust_app_disable_channel_glb(usess, uchan);
49c336c1	498	if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
f73fabfd	499	ret = LTTNG_ERR_UST_CHAN_DISABLE_FAIL;
7885e399 DG	500	goto error;
	501	}
	502
	503	uchan->enabled = 0;
	504
	505	DBG2("Channel %s disabled successfully", uchan->name);
	506
f73fabfd	507	return LTTNG_OK;
7885e399 DG	508
	509	end:
	510	error:
	511	return ret;
	512	}