Fix: add missing rcu lock for UST lookup

[lttng-tools.git] / src / bin / lttng-sessiond / trace-ust.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
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <common/common.h>
#include <common/defaults.h>

#include "trace-ust.h"

/*
 * Match function for the events hash table lookup.
 *
 * Matches by name only. Used by the disable command.
 */
int trace_ust_ht_match_event_by_name(struct cds_lfht_node *node,
		const void *_key)
{
	struct ltt_ust_event *event;
	const char *name;

	assert(node);
	assert(_key);

	event = caa_container_of(node, struct ltt_ust_event, node.node);
	name = _key;

	/* Event name */
	if (strncmp(event->attr.name, name, sizeof(event->attr.name)) != 0) {
		goto no_match;
	}

	/* Match */
	return 1;

no_match:
	return 0;
}

/*
 * Match function for the hash table lookup.
 *
 * It matches an ust event based on three attributes which are the event name,
 * the filter bytecode and the loglevel.
 */
int trace_ust_ht_match_event(struct cds_lfht_node *node, const void *_key)
{
	struct ltt_ust_event *event;
	const struct ltt_ust_ht_key *key;

	assert(node);
	assert(_key);

	event = caa_container_of(node, struct ltt_ust_event, node.node);
	key = _key;

	/* Match the 3 elements of the key: name, filter and loglevel. */

	/* Event name */
	if (strncmp(event->attr.name, key->name, sizeof(event->attr.name)) != 0) {
		goto no_match;
	}

	/* Event loglevel. */
	if (event->attr.loglevel != key->loglevel) {
		if (event->attr.loglevel_type == LTTNG_UST_LOGLEVEL_ALL
				&& key->loglevel == 0 && event->attr.loglevel == -1) {
			/*
			 * Match is accepted. This is because on event creation, the
			 * loglevel is set to -1 if the event loglevel type is ALL so 0 and
			 * -1 are accepted for this loglevel type since 0 is the one set by
			 * the API when receiving an enable event.
			 */
		} else {
			goto no_match;
		}
	}

	/* Only one of the filters is NULL, fail. */
	if ((key->filter && !event->filter) || (!key->filter && event->filter)) {
		goto no_match;
	}

	if (key->filter && event->filter) {
		/* Both filters exists, check length followed by the bytecode. */
		if (event->filter->len != key->filter->len ||
				memcmp(event->filter->data, key->filter->data,
					event->filter->len) != 0) {
			goto no_match;
		}
	}

	/* Match. */
	return 1;

no_match:
	return 0;
}

/*
 * Find the channel in the hashtable and return channel pointer. RCU read side
 * lock MUST be acquired before calling this.
 */
struct ltt_ust_channel *trace_ust_find_channel_by_name(struct lttng_ht *ht,
		char *name)
{
	struct lttng_ht_node_str *node;
	struct lttng_ht_iter iter;

	lttng_ht_lookup(ht, (void *)name, &iter);
	node = lttng_ht_iter_get_node_str(&iter);
	if (node == NULL) {
		goto error;
	}

	DBG2("Trace UST channel %s found by name", name);

	return caa_container_of(node, struct ltt_ust_channel, node);

error:
	DBG2("Trace UST channel %s not found by name", name);
	return NULL;
}

/*
 * Find the event in the hashtable and return event pointer. RCU read side lock
 * MUST be acquired before calling this.
 */
struct ltt_ust_event *trace_ust_find_event(struct lttng_ht *ht,
		char *name, struct lttng_filter_bytecode *filter, int loglevel)
{
	struct lttng_ht_node_str *node;
	struct lttng_ht_iter iter;
	struct ltt_ust_ht_key key;

	assert(name);
	assert(ht);

	key.name = name;
	key.filter = filter;
	key.loglevel = loglevel;

	cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
			trace_ust_ht_match_event, &key, &iter.iter);
	node = lttng_ht_iter_get_node_str(&iter);
	if (node == NULL) {
		goto error;
	}

	DBG2("Trace UST event %s found", key.name);

	return caa_container_of(node, struct ltt_ust_event, node);

error:
	DBG2("Trace UST event %s NOT found", key.name);
	return NULL;
}

/*
 * Allocate and initialize a ust session data structure.
 *
 * Return pointer to structure or NULL.
 */
struct ltt_ust_session *trace_ust_create_session(char *path,
		unsigned int session_id)
{
	struct ltt_ust_session *lus;

	/* Allocate a new ltt ust session */
	lus = zmalloc(sizeof(struct ltt_ust_session));
	if (lus == NULL) {
		PERROR("create ust session zmalloc");
		goto error;
	}

	/* Init data structure */
	lus->id = session_id;
	lus->start_trace = 0;

	/* Alloc UST domain hash tables */
	lus->domain_pid = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
	lus->domain_exec = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);

	/* Alloc UST global domain channels' HT */
	lus->domain_global.channels = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);

	lus->consumer = consumer_create_output(CONSUMER_DST_LOCAL);
	if (lus->consumer == NULL) {
		goto error_consumer;
	}

	/*
	 * The tmp_consumer stays NULL until a set_consumer_uri command is
	 * executed. At this point, the consumer should be nullify until an
	 * enable_consumer command. This assignment is symbolic since we've zmalloc
	 * the struct.
	 */
	lus->tmp_consumer = NULL;

	/* Use the default consumer output which is the tracing session path. */
	if (path && strlen(path) > 0) {
		int ret;

		ret = snprintf(lus->consumer->dst.trace_path, PATH_MAX,
				"%s" DEFAULT_UST_TRACE_DIR, path);
		if (ret < 0) {
			PERROR("snprintf UST consumer trace path");
			goto error_path;
		}

		/* Set session path */
		ret = snprintf(lus->pathname, PATH_MAX, "%s" DEFAULT_UST_TRACE_DIR,
				path);
		if (ret < 0) {
			PERROR("snprintf kernel traces path");
			goto error_path;
		}
	}

	DBG2("UST trace session create successful");

	return lus;

error_path:
	consumer_destroy_output(lus->consumer);
error_consumer:
	lttng_ht_destroy(lus->domain_global.channels);
	lttng_ht_destroy(lus->domain_exec);
	lttng_ht_destroy(lus->domain_pid);
	free(lus);
error:
	return NULL;
}

/*
 * Allocate and initialize a ust channel data structure.
 *
 * Return pointer to structure or NULL.
 */
struct ltt_ust_channel *trace_ust_create_channel(struct lttng_channel *chan,
		char *path)
{
	int ret;
	struct ltt_ust_channel *luc;

	assert(chan);
	assert(path);

	luc = zmalloc(sizeof(struct ltt_ust_channel));
	if (luc == NULL) {
		PERROR("ltt_ust_channel zmalloc");
		goto error;
	}

	/* Copy UST channel attributes */
	luc->attr.overwrite = chan->attr.overwrite;
	luc->attr.subbuf_size = chan->attr.subbuf_size;
	luc->attr.num_subbuf = chan->attr.num_subbuf;
	luc->attr.switch_timer_interval = chan->attr.switch_timer_interval;
	luc->attr.read_timer_interval = chan->attr.read_timer_interval;
	luc->attr.output = (enum lttng_ust_output) chan->attr.output;

	/* Translate to UST output enum */
	switch (luc->attr.output) {
	default:
		luc->attr.output = LTTNG_UST_MMAP;
		break;
	}

	/* Copy channel name */
	strncpy(luc->name, chan->name, sizeof(luc->name));
	luc->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';

	/* Init node */
	lttng_ht_node_init_str(&luc->node, luc->name);
	/* Alloc hash tables */
	luc->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
	luc->ctx = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);

	/* Set trace output path */
	ret = snprintf(luc->pathname, PATH_MAX, "%s", path);
	if (ret < 0) {
		PERROR("asprintf ust create channel");
		goto error_free_channel;
	}

	DBG2("Trace UST channel %s created", luc->name);

	return luc;

error_free_channel:
	lttng_ht_destroy(luc->ctx);
	lttng_ht_destroy(luc->events);
	free(luc);
error:
	return NULL;
}

/*
 * Allocate and initialize a ust event. Set name and event type.
 *
 * Return pointer to structure or NULL.
 */
struct ltt_ust_event *trace_ust_create_event(struct lttng_event *ev,
		struct lttng_filter_bytecode *filter)
{
	struct ltt_ust_event *lue;

	assert(ev);

	lue = zmalloc(sizeof(struct ltt_ust_event));
	if (lue == NULL) {
		PERROR("ust event zmalloc");
		goto error;
	}

	switch (ev->type) {
	case LTTNG_EVENT_PROBE:
		lue->attr.instrumentation = LTTNG_UST_PROBE;
		break;
	case LTTNG_EVENT_FUNCTION:
		lue->attr.instrumentation = LTTNG_UST_FUNCTION;
		break;
	case LTTNG_EVENT_FUNCTION_ENTRY:
		lue->attr.instrumentation = LTTNG_UST_FUNCTION;
		break;
	case LTTNG_EVENT_TRACEPOINT:
		lue->attr.instrumentation = LTTNG_UST_TRACEPOINT;
		break;
	default:
		ERR("Unknown ust instrumentation type (%d)", ev->type);
		goto error_free_event;
	}

	/* Copy event name */
	strncpy(lue->attr.name, ev->name, LTTNG_UST_SYM_NAME_LEN);
	lue->attr.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';

	switch (ev->loglevel_type) {
	case LTTNG_EVENT_LOGLEVEL_ALL:
		lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_ALL;
		lue->attr.loglevel = -1;	/* Force to -1 */
		break;
	case LTTNG_EVENT_LOGLEVEL_RANGE:
		lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_RANGE;
		lue->attr.loglevel = ev->loglevel;
		break;
	case LTTNG_EVENT_LOGLEVEL_SINGLE:
		lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_SINGLE;
		lue->attr.loglevel = ev->loglevel;
		break;
	default:
		ERR("Unknown ust loglevel type (%d)", ev->loglevel_type);
		goto error_free_event;
	}

	/* Same layout. */
	lue->filter = (struct lttng_ust_filter_bytecode *) filter;

	/* Init node */
	lttng_ht_node_init_str(&lue->node, lue->attr.name);

	DBG2("Trace UST event %s, loglevel (%d,%d) created",
		lue->attr.name, lue->attr.loglevel_type,
		lue->attr.loglevel);

	return lue;

error_free_event:
	free(lue);
error:
	return NULL;
}

/*
 * Allocate and initialize a ust metadata.
 *
 * Return pointer to structure or NULL.
 */
struct ltt_ust_metadata *trace_ust_create_metadata(char *path)
{
	int ret;
	struct ltt_ust_metadata *lum;

	assert(path);

	lum = zmalloc(sizeof(struct ltt_ust_metadata));
	if (lum == NULL) {
		PERROR("ust metadata zmalloc");
		goto error;
	}

	/* Set default attributes */
	lum->attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
	lum->attr.subbuf_size = default_get_metadata_subbuf_size();
	lum->attr.num_subbuf = DEFAULT_METADATA_SUBBUF_NUM;
	lum->attr.switch_timer_interval = DEFAULT_CHANNEL_SWITCH_TIMER;
	lum->attr.read_timer_interval = DEFAULT_CHANNEL_READ_TIMER;
	lum->attr.output = LTTNG_UST_MMAP;

	lum->handle = -1;
	/* Set metadata trace path */
	ret = snprintf(lum->pathname, PATH_MAX, "%s/metadata", path);
	if (ret < 0) {
		PERROR("asprintf ust metadata");
		goto error_free_metadata;
	}

	return lum;

error_free_metadata:
	free(lum);
error:
	return NULL;
}

/*
 * Allocate and initialize an UST context.
 *
 * Return pointer to structure or NULL.
 */
struct ltt_ust_context *trace_ust_create_context(
		struct lttng_event_context *ctx)
{
	struct ltt_ust_context *uctx;
	enum lttng_ust_context_type utype;

	assert(ctx);

	switch (ctx->ctx) {
	case LTTNG_EVENT_CONTEXT_VTID:
		utype = LTTNG_UST_CONTEXT_VTID;
		break;
	case LTTNG_EVENT_CONTEXT_VPID:
		utype = LTTNG_UST_CONTEXT_VPID;
		break;
	case LTTNG_EVENT_CONTEXT_PTHREAD_ID:
		utype = LTTNG_UST_CONTEXT_PTHREAD_ID;
		break;
	case LTTNG_EVENT_CONTEXT_PROCNAME:
		utype = LTTNG_UST_CONTEXT_PROCNAME;
		break;
	default:
		ERR("Invalid UST context");
		return NULL;
	}

	uctx = zmalloc(sizeof(struct ltt_ust_context));
	if (uctx == NULL) {
		PERROR("zmalloc ltt_ust_context");
		goto error;
	}

	uctx->ctx.ctx = utype;
	lttng_ht_node_init_ulong(&uctx->node, (unsigned long) uctx->ctx.ctx);

	return uctx;

error:
	return NULL;
}

/*
 * RCU safe free context structure.
 */
static void destroy_context_rcu(struct rcu_head *head)
{
	struct lttng_ht_node_ulong *node =
		caa_container_of(head, struct lttng_ht_node_ulong, head);
	struct ltt_ust_context *ctx =
		caa_container_of(node, struct ltt_ust_context, node);

	free(ctx);
}

/*
 * Cleanup UST context hash table.
 */
static void destroy_contexts(struct lttng_ht *ht)
{
	int ret;
	struct lttng_ht_node_ulong *node;
	struct lttng_ht_iter iter;

	assert(ht);

	cds_lfht_for_each_entry(ht->ht, &iter.iter, node, node) {
		ret = lttng_ht_del(ht, &iter);
		if (!ret) {
			call_rcu(&node->head, destroy_context_rcu);
		}
	}

	lttng_ht_destroy(ht);
}

/*
 * Cleanup ust event structure.
 */
void trace_ust_destroy_event(struct ltt_ust_event *event)
{
	assert(event);

	DBG2("Trace destroy UST event %s", event->attr.name);
	free(event->filter);
	free(event);
}

/*
 * URCU intermediate call to complete destroy event.
 */
static void destroy_event_rcu(struct rcu_head *head)
{
	struct lttng_ht_node_str *node =
		caa_container_of(head, struct lttng_ht_node_str, head);
	struct ltt_ust_event *event =
		caa_container_of(node, struct ltt_ust_event, node);

	trace_ust_destroy_event(event);
}

/*
 * Cleanup UST events hashtable.
 */
static void destroy_events(struct lttng_ht *events)
{
	int ret;
	struct lttng_ht_node_str *node;
	struct lttng_ht_iter iter;

	assert(events);

	cds_lfht_for_each_entry(events->ht, &iter.iter, node, node) {
		ret = lttng_ht_del(events, &iter);
		assert(!ret);
		call_rcu(&node->head, destroy_event_rcu);
	}

	lttng_ht_destroy(events);
}

/*
 * Cleanup ust channel structure.
 */
void trace_ust_destroy_channel(struct ltt_ust_channel *channel)
{
	assert(channel);

	DBG2("Trace destroy UST channel %s", channel->name);

	rcu_read_lock();

	/* Destroying all events of the channel */
	destroy_events(channel->events);
	/* Destroying all context of the channel */
	destroy_contexts(channel->ctx);

	free(channel);

	rcu_read_unlock();
}

/*
 * URCU intermediate call to complete destroy channel.
 */
static void destroy_channel_rcu(struct rcu_head *head)
{
	struct lttng_ht_node_str *node =
		caa_container_of(head, struct lttng_ht_node_str, head);
	struct ltt_ust_channel *channel =
		caa_container_of(node, struct ltt_ust_channel, node);

	trace_ust_destroy_channel(channel);
}

/*
 * Cleanup ust metadata structure.
 */
void trace_ust_destroy_metadata(struct ltt_ust_metadata *metadata)
{
	assert(metadata);

	if (!metadata->handle) {
		return;
	}
	DBG2("Trace UST destroy metadata %d", metadata->handle);
	free(metadata);
}

/*
 * Iterate over a hash table containing channels and cleanup safely.
 */
static void destroy_channels(struct lttng_ht *channels)
{
	int ret;
	struct lttng_ht_node_str *node;
	struct lttng_ht_iter iter;

	assert(channels);

	rcu_read_lock();

	cds_lfht_for_each_entry(channels->ht, &iter.iter, node, node) {
		ret = lttng_ht_del(channels, &iter);
		assert(!ret);
		call_rcu(&node->head, destroy_channel_rcu);
	}

	lttng_ht_destroy(channels);

	rcu_read_unlock();
}

/*
 * Cleanup UST pid domain.
 */
static void destroy_domain_pid(struct lttng_ht *ht)
{
	int ret;
	struct lttng_ht_iter iter;
	struct ltt_ust_domain_pid *dpid;

	assert(ht);

	cds_lfht_for_each_entry(ht->ht, &iter.iter, dpid, node.node) {
		ret = lttng_ht_del(ht , &iter);
		assert(!ret);
		destroy_channels(dpid->channels);
	}

	lttng_ht_destroy(ht);
}

/*
 * Cleanup UST exec name domain.
 */
static void destroy_domain_exec(struct lttng_ht *ht)
{
	int ret;
	struct lttng_ht_iter iter;
	struct ltt_ust_domain_exec *dexec;

	assert(ht);

	cds_lfht_for_each_entry(ht->ht, &iter.iter, dexec, node.node) {
		ret = lttng_ht_del(ht , &iter);
		assert(!ret);
		destroy_channels(dexec->channels);
	}

	lttng_ht_destroy(ht);
}

/*
 * Cleanup UST global domain.
 */
static void destroy_domain_global(struct ltt_ust_domain_global *dom)
{
	assert(dom);

	destroy_channels(dom->channels);
}

/*
 * Cleanup ust session structure
 */
void trace_ust_destroy_session(struct ltt_ust_session *session)
{
	assert(session);

	rcu_read_lock();

	DBG2("Trace UST destroy session %u", session->id);

	/* Cleaning up UST domain */
	destroy_domain_global(&session->domain_global);
	destroy_domain_pid(session->domain_pid);
	destroy_domain_exec(session->domain_exec);

	consumer_destroy_output(session->consumer);
	consumer_destroy_output(session->tmp_consumer);

	free(session);

	rcu_read_unlock();
}