[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>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 */

#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 "lttng-ust-ctl.h"
#include "lttng-ust-error.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;
	struct lttng_channel_extended *extended_attr = NULL;

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

	extended_attr = zmalloc(sizeof(struct lttng_channel_extended));
	if (!extended_attr) {
		PERROR("zmalloc channel extended init");
		goto error;
	}

	chan->attr.extended.ptr = extended_attr;

	/* 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;
		extended_attr->blocking_timeout = DEFAULT_KERNEL_CHANNEL_BLOCKING_TIMEOUT;
		extended_attr->monitor_timer_interval =
			DEFAULT_KERNEL_CHANNEL_MONITOR_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;
			extended_attr->blocking_timeout = DEFAULT_UST_UID_CHANNEL_BLOCKING_TIMEOUT;
			extended_attr->monitor_timer_interval =
				DEFAULT_UST_UID_CHANNEL_MONITOR_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_PID_CHANNEL_LIVE_TIMER;
			extended_attr->blocking_timeout = DEFAULT_UST_PID_CHANNEL_BLOCKING_TIMEOUT;
			extended_attr->monitor_timer_interval =
				DEFAULT_UST_PID_CHANNEL_MONITOR_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(extended_attr);
	free(chan);
error_alloc:
	return NULL;
}

void channel_attr_destroy(struct lttng_channel *channel)
{
	if (!channel) {
		return;
	}
	free(channel->attr.extended.ptr);
	free(channel);
}

/*
 * 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;
}

static int channel_validate_kernel(struct lttng_channel *attr)
{
	/* Kernel channels do not support blocking timeout. */
	if (((struct lttng_channel_extended *)attr->attr.extended.ptr)->blocking_timeout) {
		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;
	}

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

	if (channel_validate_kernel(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:
	channel_attr_destroy(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;
	} else {
		uchan->enabled = 1;
		DBG2("Channel %s enabled successfully", uchan->name);
	}

	if (!usess->active) {
		/*
		 * The channel will be activated against the apps
		 * when the session is started as part of the
		 * application channel "synchronize" operation.
		 */
		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);


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;
	}

	/* 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);
		}
	}

	channel_attr_destroy(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:
	channel_attr_destroy(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;
	}
	if (!usess->active) {
		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
	1	/*
	2	* Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
	3	* Copyright (C) 2016 Jérémie Galarneau <jeremie.galarneau@efficios.com>
	4	*
	5	* SPDX-License-Identifier: GPL-2.0-only
	6	*
	7	*/
	8
	9	#define _LGPL_SOURCE
	10	#include <inttypes.h>
	11	#include <string.h>
	12	#include <unistd.h>
	13
	14	#include <common/common.h>
	15	#include <common/defaults.h>
	16	#include <common/sessiond-comm/sessiond-comm.h>
	17
	18	#include "channel.h"
	19	#include "lttng-sessiond.h"
	20	#include "kernel.h"
	21	#include "lttng-ust-ctl.h"
	22	#include "lttng-ust-error.h"
	23	#include "utils.h"
	24	#include "ust-app.h"
	25	#include "agent.h"
	26
	27	/*
	28	* Return allocated channel attributes.
	29	*/
	30	struct lttng_channel *channel_new_default_attr(int dom,
	31	enum lttng_buffer_type type)
	32	{
	33	struct lttng_channel *chan;
	34	const char *channel_name = DEFAULT_CHANNEL_NAME;
	35	struct lttng_channel_extended *extended_attr = NULL;
	36
	37	chan = zmalloc(sizeof(struct lttng_channel));
	38	if (chan == NULL) {
	39	PERROR("zmalloc channel init");
	40	goto error_alloc;
	41	}
	42
	43	extended_attr = zmalloc(sizeof(struct lttng_channel_extended));
	44	if (!extended_attr) {
	45	PERROR("zmalloc channel extended init");
	46	goto error;
	47	}
	48
	49	chan->attr.extended.ptr = extended_attr;
	50
	51	/* Same for all domains. */
	52	chan->attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
	53	chan->attr.tracefile_size = DEFAULT_CHANNEL_TRACEFILE_SIZE;
	54	chan->attr.tracefile_count = DEFAULT_CHANNEL_TRACEFILE_COUNT;
	55
	56	switch (dom) {
	57	case LTTNG_DOMAIN_KERNEL:
	58	assert(type == LTTNG_BUFFER_GLOBAL);
	59	chan->attr.subbuf_size =
	60	default_get_kernel_channel_subbuf_size();
	61	chan->attr.num_subbuf = DEFAULT_KERNEL_CHANNEL_SUBBUF_NUM;
	62	chan->attr.output = DEFAULT_KERNEL_CHANNEL_OUTPUT;
	63	chan->attr.switch_timer_interval = DEFAULT_KERNEL_CHANNEL_SWITCH_TIMER;
	64	chan->attr.read_timer_interval = DEFAULT_KERNEL_CHANNEL_READ_TIMER;
	65	chan->attr.live_timer_interval = DEFAULT_KERNEL_CHANNEL_LIVE_TIMER;
	66	extended_attr->blocking_timeout = DEFAULT_KERNEL_CHANNEL_BLOCKING_TIMEOUT;
	67	extended_attr->monitor_timer_interval =
	68	DEFAULT_KERNEL_CHANNEL_MONITOR_TIMER;
	69	break;
	70	case LTTNG_DOMAIN_JUL:
	71	channel_name = DEFAULT_JUL_CHANNEL_NAME;
	72	goto common_ust;
	73	case LTTNG_DOMAIN_LOG4J:
	74	channel_name = DEFAULT_LOG4J_CHANNEL_NAME;
	75	goto common_ust;
	76	case LTTNG_DOMAIN_PYTHON:
	77	channel_name = DEFAULT_PYTHON_CHANNEL_NAME;
	78	goto common_ust;
	79	case LTTNG_DOMAIN_UST:
	80	common_ust:
	81	switch (type) {
	82	case LTTNG_BUFFER_PER_UID:
	83	chan->attr.subbuf_size = default_get_ust_uid_channel_subbuf_size();
	84	chan->attr.num_subbuf = DEFAULT_UST_UID_CHANNEL_SUBBUF_NUM;
	85	chan->attr.output = DEFAULT_UST_UID_CHANNEL_OUTPUT;
	86	chan->attr.switch_timer_interval =
	87	DEFAULT_UST_UID_CHANNEL_SWITCH_TIMER;
	88	chan->attr.read_timer_interval =
	89	DEFAULT_UST_UID_CHANNEL_READ_TIMER;
	90	chan->attr.live_timer_interval =
	91	DEFAULT_UST_UID_CHANNEL_LIVE_TIMER;
	92	extended_attr->blocking_timeout = DEFAULT_UST_UID_CHANNEL_BLOCKING_TIMEOUT;
	93	extended_attr->monitor_timer_interval =
	94	DEFAULT_UST_UID_CHANNEL_MONITOR_TIMER;
	95	break;
	96	case LTTNG_BUFFER_PER_PID:
	97	default:
	98	chan->attr.subbuf_size = default_get_ust_pid_channel_subbuf_size();
	99	chan->attr.num_subbuf = DEFAULT_UST_PID_CHANNEL_SUBBUF_NUM;
	100	chan->attr.output = DEFAULT_UST_PID_CHANNEL_OUTPUT;
	101	chan->attr.switch_timer_interval =
	102	DEFAULT_UST_PID_CHANNEL_SWITCH_TIMER;
	103	chan->attr.read_timer_interval =
	104	DEFAULT_UST_PID_CHANNEL_READ_TIMER;
	105	chan->attr.live_timer_interval =
	106	DEFAULT_UST_PID_CHANNEL_LIVE_TIMER;
	107	extended_attr->blocking_timeout = DEFAULT_UST_PID_CHANNEL_BLOCKING_TIMEOUT;
	108	extended_attr->monitor_timer_interval =
	109	DEFAULT_UST_PID_CHANNEL_MONITOR_TIMER;
	110	break;
	111	}
	112	break;
	113	default:
	114	goto error; /* Not implemented */
	115	}
	116
	117	if (snprintf(chan->name, sizeof(chan->name), "%s",
	118	channel_name) < 0) {
	119	PERROR("snprintf default channel name");
	120	goto error;
	121	}
	122	return chan;
	123
	124	error:
	125	free(extended_attr);
	126	free(chan);
	127	error_alloc:
	128	return NULL;
	129	}
	130
	131	void channel_attr_destroy(struct lttng_channel *channel)
	132	{
	133	if (!channel) {
	134	return;
	135	}
	136	free(channel->attr.extended.ptr);
	137	free(channel);
	138	}
	139
	140	/*
	141	* Disable kernel channel of the kernel session.
	142	*/
	143	int channel_kernel_disable(struct ltt_kernel_session *ksession,
	144	char *channel_name)
	145	{
	146	int ret;
	147	struct ltt_kernel_channel *kchan;
	148
	149	assert(ksession);
	150	assert(channel_name);
	151
	152	kchan = trace_kernel_get_channel_by_name(channel_name, ksession);
	153	if (kchan == NULL) {
	154	ret = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
	155	goto error;
	156	}
	157
	158	/* Only if channel is enabled disable it. */
	159	if (kchan->enabled == 1) {
	160	ret = kernel_disable_channel(kchan);
	161	if (ret < 0 && ret != -EEXIST) {
	162	ret = LTTNG_ERR_KERN_CHAN_DISABLE_FAIL;
	163	goto error;
	164	}
	165	}
	166
	167	ret = LTTNG_OK;
	168
	169	error:
	170	return ret;
	171	}
	172
	173	/*
	174	* Enable kernel channel of the kernel session.
	175	*/
	176	int channel_kernel_enable(struct ltt_kernel_session *ksession,
	177	struct ltt_kernel_channel *kchan)
	178	{
	179	int ret;
	180
	181	assert(ksession);
	182	assert(kchan);
	183
	184	if (kchan->enabled == 0) {
	185	ret = kernel_enable_channel(kchan);
	186	if (ret < 0) {
	187	ret = LTTNG_ERR_KERN_CHAN_ENABLE_FAIL;
	188	goto error;
	189	}
	190	} else {
	191	ret = LTTNG_ERR_KERN_CHAN_EXIST;
	192	goto error;
	193	}
	194
	195	ret = LTTNG_OK;
	196
	197	error:
	198	return ret;
	199	}
	200
	201	static int channel_validate(struct lttng_channel *attr)
	202	{
	203	/*
	204	* The ringbuffer (both in user space and kernel) behaves badly
	205	* in overwrite mode and with less than 2 subbuffers so block it
	206	* right away and send back an invalid attribute error.
	207	*/
	208	if (attr->attr.overwrite && attr->attr.num_subbuf < 2) {
	209	return -1;
	210	}
	211	return 0;
	212	}
	213
	214	static int channel_validate_kernel(struct lttng_channel *attr)
	215	{
	216	/* Kernel channels do not support blocking timeout. */
	217	if (((struct lttng_channel_extended *)attr->attr.extended.ptr)->blocking_timeout) {
	218	return -1;
	219	}
	220	return 0;
	221	}
	222
	223	/*
	224	* Create kernel channel of the kernel session and notify kernel thread.
	225	*/
	226	int channel_kernel_create(struct ltt_kernel_session *ksession,
	227	struct lttng_channel *attr, int kernel_pipe)
	228	{
	229	int ret;
	230	struct lttng_channel *defattr = NULL;
	231
	232	assert(ksession);
	233
	234	/* Creating channel attributes if needed */
	235	if (attr == NULL) {
	236	defattr = channel_new_default_attr(LTTNG_DOMAIN_KERNEL,
	237	LTTNG_BUFFER_GLOBAL);
	238	if (defattr == NULL) {
	239	ret = LTTNG_ERR_FATAL;
	240	goto error;
	241	}
	242	attr = defattr;
	243	}
	244
	245	/*
	246	* Set the overwrite mode for this channel based on the session
	247	* type unless the client explicitly overrides the channel mode.
	248	*/
	249	if (attr->attr.overwrite == DEFAULT_CHANNEL_OVERWRITE) {
	250	attr->attr.overwrite = !!ksession->snapshot_mode;
	251	}
	252
	253	/* Validate common channel properties. */
	254	if (channel_validate(attr) < 0) {
	255	ret = LTTNG_ERR_INVALID;
	256	goto error;
	257	}
	258
	259	if (channel_validate_kernel(attr) < 0) {
	260	ret = LTTNG_ERR_INVALID;
	261	goto error;
	262	}
	263
	264	/* Channel not found, creating it */
	265	ret = kernel_create_channel(ksession, attr);
	266	if (ret < 0) {
	267	ret = LTTNG_ERR_KERN_CHAN_FAIL;
	268	goto error;
	269	}
	270
	271	/* Notify kernel thread that there is a new channel */
	272	ret = notify_thread_pipe(kernel_pipe);
	273	if (ret < 0) {
	274	ret = LTTNG_ERR_FATAL;
	275	goto error;
	276	}
	277
	278	ret = LTTNG_OK;
	279	error:
	280	channel_attr_destroy(defattr);
	281	return ret;
	282	}
	283
	284	/*
	285	* Enable UST channel for session and domain.
	286	*/
	287	int channel_ust_enable(struct ltt_ust_session *usess,
	288	struct ltt_ust_channel *uchan)
	289	{
	290	int ret = LTTNG_OK;
	291
	292	assert(usess);
	293	assert(uchan);
	294
	295	/* If already enabled, everything is OK */
	296	if (uchan->enabled) {
	297	DBG3("Channel %s already enabled. Skipping", uchan->name);
	298	ret = LTTNG_ERR_UST_CHAN_EXIST;
	299	goto end;
	300	} else {
	301	uchan->enabled = 1;
	302	DBG2("Channel %s enabled successfully", uchan->name);
	303	}
	304
	305	if (!usess->active) {
	306	/*
	307	* The channel will be activated against the apps
	308	* when the session is started as part of the
	309	* application channel "synchronize" operation.
	310	*/
	311	goto end;
	312	}
	313
	314	DBG2("Channel %s being enabled in UST domain", uchan->name);
	315
	316	/*
	317	* Enable channel for UST global domain on all applications. Ignore return
	318	* value here since whatever error we got, it means that the channel was
	319	* not created on one or many registered applications and we can not report
	320	* this to the user yet. However, at this stage, the channel was
	321	* successfully created on the session daemon side so the enable-channel
	322	* command is a success.
	323	*/
	324	(void) ust_app_enable_channel_glb(usess, uchan);
	325
	326
	327	end:
	328	return ret;
	329	}
	330
	331	/*
	332	* Create UST channel for session and domain.
	333	*/
	334	int channel_ust_create(struct ltt_ust_session *usess,
	335	struct lttng_channel *attr, enum lttng_buffer_type type)
	336	{
	337	int ret = LTTNG_OK;
	338	struct ltt_ust_channel *uchan = NULL;
	339	struct lttng_channel *defattr = NULL;
	340	enum lttng_domain_type domain = LTTNG_DOMAIN_UST;
	341	bool chan_published = false;
	342
	343	assert(usess);
	344
	345	/* Creating channel attributes if needed */
	346	if (attr == NULL) {
	347	defattr = channel_new_default_attr(LTTNG_DOMAIN_UST, type);
	348	if (defattr == NULL) {
	349	ret = LTTNG_ERR_FATAL;
	350	goto error;
	351	}
	352	attr = defattr;
	353	} else {
	354	/*
	355	* HACK: Set the channel's subdomain (JUL, Log4j, Python, etc.)
	356	* based on the default name.
	357	*/
	358	if (!strcmp(attr->name, DEFAULT_JUL_CHANNEL_NAME)) {
	359	domain = LTTNG_DOMAIN_JUL;
	360	} else if (!strcmp(attr->name, DEFAULT_LOG4J_CHANNEL_NAME)) {
	361	domain = LTTNG_DOMAIN_LOG4J;
	362	} else if (!strcmp(attr->name, DEFAULT_PYTHON_CHANNEL_NAME)) {
	363	domain = LTTNG_DOMAIN_PYTHON;
	364	}
	365	}
	366
	367	/*
	368	* Set the overwrite mode for this channel based on the session
	369	* type unless the client explicitly overrides the channel mode.
	370	*/
	371	if (attr->attr.overwrite == DEFAULT_CHANNEL_OVERWRITE) {
	372	attr->attr.overwrite = !!usess->snapshot_mode;
	373	}
	374
	375	/* Enforce mmap output for snapshot sessions. */
	376	if (usess->snapshot_mode) {
	377	attr->attr.output = LTTNG_EVENT_MMAP;
	378	}
	379
	380	/* Validate common channel properties. */
	381	if (channel_validate(attr) < 0) {
	382	ret = LTTNG_ERR_INVALID;
	383	goto error;
	384	}
	385
	386	/*
	387	* Validate UST buffer size and number of buffers: must both be power of 2
	388	* and nonzero. We validate right here for UST, because applications will
	389	* not report the error to the user (unlike kernel tracing).
	390	*/
	391	if (!attr->attr.subbuf_size \|\|
	392	(attr->attr.subbuf_size & (attr->attr.subbuf_size - 1))) {
	393	ret = LTTNG_ERR_INVALID;
	394	goto error;
	395	}
	396
	397	/*
	398	* Invalid subbuffer size if it's lower then the page size.
	399	*/
	400	if (attr->attr.subbuf_size < page_size) {
	401	ret = LTTNG_ERR_INVALID;
	402	goto error;
	403	}
	404
	405	if (!attr->attr.num_subbuf \|\|
	406	(attr->attr.num_subbuf & (attr->attr.num_subbuf - 1))) {
	407	ret = LTTNG_ERR_INVALID;
	408	goto error;
	409	}
	410
	411	if (attr->attr.output != LTTNG_EVENT_MMAP) {
	412	ret = LTTNG_ERR_NOT_SUPPORTED;
	413	goto error;
	414	}
	415
	416	/*
	417	* The tracefile_size should not be < to the subbuf_size, otherwise
	418	* we won't be able to write the packets on disk
	419	*/
	420	if ((attr->attr.tracefile_size > 0) &&
	421	(attr->attr.tracefile_size < attr->attr.subbuf_size)) {
	422	ret = LTTNG_ERR_INVALID;
	423	goto error;
	424	}
	425
	426	/* Validate buffer type. */
	427	switch (type) {
	428	case LTTNG_BUFFER_PER_PID:
	429	break;
	430	case LTTNG_BUFFER_PER_UID:
	431	break;
	432	default:
	433	ret = LTTNG_ERR_BUFFER_NOT_SUPPORTED;
	434	goto error;
	435	}
	436
	437	/* Create UST channel */
	438	uchan = trace_ust_create_channel(attr, domain);
	439	if (uchan == NULL) {
	440	ret = LTTNG_ERR_FATAL;
	441	goto error;
	442	}
	443
	444	uchan->enabled = 1;
	445	if (trace_ust_is_max_id(usess->used_channel_id)) {
	446	ret = LTTNG_ERR_UST_CHAN_FAIL;
	447	goto error;
	448	}
	449	uchan->id = trace_ust_get_next_chan_id(usess);
	450
	451	DBG2("Channel %s is being created for UST with buffer %d and id %" PRIu64,
	452	uchan->name, type, uchan->id);
	453
	454	/* Flag session buffer type. */
	455	if (!usess->buffer_type_changed) {
	456	usess->buffer_type = type;
	457	usess->buffer_type_changed = 1;
	458	} else if (usess->buffer_type != type) {
	459	/* Buffer type was already set. Refuse to create channel. */
	460	ret = LTTNG_ERR_BUFFER_TYPE_MISMATCH;
	461	goto error_free_chan;
	462	}
	463
	464	/* Adding the channel to the channel hash table. */
	465	rcu_read_lock();
	466	if (strncmp(uchan->name, DEFAULT_METADATA_NAME,
	467	sizeof(uchan->name))) {
	468	lttng_ht_add_unique_str(usess->domain_global.channels, &uchan->node);
	469	chan_published = true;
	470	} else {
	471	/*
	472	* Copy channel attribute to session if this is metadata so if NO
	473	* application exists we can access that data in the shadow copy during
	474	* the global update of newly registered application.
	475	*/
	476	memcpy(&usess->metadata_attr, &uchan->attr,
	477	sizeof(usess->metadata_attr));
	478	}
	479	rcu_read_unlock();
	480
	481	DBG2("Channel %s created successfully", uchan->name);
	482	if (domain != LTTNG_DOMAIN_UST) {
	483	struct agent *agt = trace_ust_find_agent(usess, domain);
	484
	485	if (!agt) {
	486	agt = agent_create(domain);
	487	if (!agt) {
	488	ret = LTTNG_ERR_NOMEM;
	489	goto error_remove_chan;
	490	}
	491	agent_add(agt, usess->agents);
	492	}
	493	}
	494
	495	channel_attr_destroy(defattr);
	496	return LTTNG_OK;
	497
	498	error_remove_chan:
	499	if (chan_published) {
	500	trace_ust_delete_channel(usess->domain_global.channels, uchan);
	501	}
	502	error_free_chan:
	503	trace_ust_destroy_channel(uchan);
	504	error:
	505	channel_attr_destroy(defattr);
	506	return ret;
	507	}
	508
	509	/*
	510	* Disable UST channel for session and domain.
	511	*/
	512	int channel_ust_disable(struct ltt_ust_session *usess,
	513	struct ltt_ust_channel *uchan)
	514	{
	515	int ret = LTTNG_OK;
	516
	517	assert(usess);
	518	assert(uchan);
	519
	520	/* Already disabled */
	521	if (uchan->enabled == 0) {
	522	DBG2("Channel UST %s already disabled", uchan->name);
	523	goto end;
	524	}
	525	if (!usess->active) {
	526	goto end;
	527	}
	528
	529	DBG2("Channel %s being disabled in UST global domain", uchan->name);
	530	/* Disable channel for global domain */
	531	ret = ust_app_disable_channel_glb(usess, uchan);
	532	if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
	533	ret = LTTNG_ERR_UST_CHAN_DISABLE_FAIL;
	534	goto error;
	535	}
	536
	537	uchan->enabled = 0;
	538
	539	DBG2("Channel %s disabled successfully", uchan->name);
	540
	541	return LTTNG_OK;
	542
	543	end:
	544	error:
	545	return ret;
	546	}