[deliverable/lttng-modules.git] / ltt-events.c

/*
 * ltt-events.c
 *
 * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * Holds LTTng per-session event registry.
 */

#include <linux/module.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>	/* For vmalloc_sync_all */
#include "ltt-events.h"

static LIST_HEAD(sessions);
static LIST_HEAD(ltt_transport_list);
static DEFINE_MUTEX(sessions_mutex);
static struct kmem_cache *event_cache;

static void synchronize_trace(void)
{
	synchronize_sched();
#ifdef CONFIG_PREEMPT_RT
	synchronize_rcu();
#endif
}

struct ltt_session *ltt_session_create(void)
{
	struct ltt_session *session;

	mutex_lock(&sessions_mutex);
	session = kzalloc(sizeof(struct ltt_session), GFP_KERNEL);
	if (!session)
		return NULL;
	INIT_LIST_HEAD(&session->chan);
	INIT_LIST_HEAD(&session->events);
	list_add(&session->list, &sessions);
	mutex_unlock(&sessions_mutex);
	return session;
}

void ltt_session_destroy(struct ltt_session *session)
{
	struct ltt_channel *chan, *tmpchan;
	struct ltt_event *event, *tmpevent;

	mutex_lock(&sessions_mutex);
	session->active = 0;
	synchronize_trace();	/* Wait for in-flight events to complete */
	list_for_each_entry_safe(event, tmpevent, &session->events, list)
		_ltt_event_destroy(event);
	list_for_each_entry_safe(chan, tmpchan, &session->chan, list)
		_ltt_channel_destroy(chan);
	list_del(&session->list);
	mutex_unlock(&sessions_mutex);
	kfree(session);
}

int ltt_session_start(struct ltt_session *session)
{
	int ret = 0;

	mutex_lock(&sessions_mutex);
	if (session->active) {
		ret = -EBUSY;
		goto end;
	}
	session->active = 1;
	synchronize_trace();	/* Wait for in-flight events to complete */
end:
	mutex_unlock(&sessions_mutex);
	return ret;
}

int ltt_session_stop(struct ltt_session *session)
{
	int ret = 0;

	mutex_lock(&sessions_mutex);
	if (!session->active) {
		ret = -EBUSY;
		goto end;
	}
	session->active = 0;
	synchronize_trace();	/* Wait for in-flight events to complete */
end:
	mutex_unlock(&sessions_mutex);
	return ret;
}

static struct ltt_transport *ltt_transport_find(char *name)
{
	struct ltt_transport *transport;

	list_for_each_entry(transport, &ltt_transport_list, node) {
		if (!strcmp(transport->name, name))
			return transport;
	}
	return NULL;
}

struct ltt_channel *ltt_channel_create(struct ltt_session *session,
				       int overwrite, void *buf_addr,
				       size_t subbuf_size, size_t num_subbuf,
				       unsigned int switch_timer_interval,
				       unsigned int read_timer_interval)
{
	struct ltt_channel *chan;
	struct ltt_transport *transport;
	char *transport_name;

	mutex_lock(&sessions_mutex);
	if (session->active) {
		printk(KERN_WARNING "LTTng refusing to add channel to active session\n");
		goto active;	/* Refuse to add channel to active session */
	}
	transport_name = overwrite ? "relay-overwrite" : "relay-discard";
	transport = ltt_transport_find(transport_name);
	if (!transport) {
		printk(KERN_WARNING "LTTng transport %s not found\n",
		       transport_name);
		goto notransport;
	}
	printk("got transport\n");
	chan = kzalloc(sizeof(struct ltt_channel), GFP_KERNEL);
	if (!chan)
		goto nomem;
	chan->session = session;
	init_waitqueue_head(&chan->notify_wait);
	chan->chan = transport->ops.channel_create("[lttng]", session, buf_addr,
			subbuf_size, num_subbuf, switch_timer_interval,
			read_timer_interval);
	printk("chan create %p\n", chan->chan);
	if (!chan->chan)
		goto create_error;
	chan->ops = &transport->ops;
	list_add(&chan->list, &session->chan);
	mutex_unlock(&sessions_mutex);
	return chan;

create_error:
	kfree(chan);
nomem:
notransport:
active:
	mutex_unlock(&sessions_mutex);
	return NULL;
}

/*
 * Only used internally at session destruction.
 */
void _ltt_channel_destroy(struct ltt_channel *chan)
{
	chan->ops->channel_destroy(chan->chan);
	list_del(&chan->list);
	kfree(chan);
}

/*
 * Supports event creation while tracing session is active.
 */
struct ltt_event *ltt_event_create(struct ltt_channel *chan, char *name,
				   enum instrum_type itype,
				   void *probe, void *filter)
{
	struct ltt_event *event;
	int ret;

	mutex_lock(&sessions_mutex);
	if (chan->free_event_id == -1UL)
		goto full;
	/*
	 * This is O(n^2) (for each event loop called at event creation).
	 * Might require a hash if we have lots of events.
	 */
	list_for_each_entry(event, &chan->session->events, list)
		if (!strcmp(event->name, name))
			goto exist;
	event = kmem_cache_zalloc(event_cache, GFP_KERNEL);
	if (!event)
		goto cache_error;
	event->name = kmalloc(strlen(name) + 1, GFP_KERNEL);
	if (!event->name)
		goto name_error;
	strcpy(event->name, name);
	event->chan = chan;
	event->probe = probe;
	event->filter = filter;
	event->id = chan->free_event_id++;
	event->itype = itype;
	/* Populate ltt_event structure before tracepoint registration. */
	smp_wmb();
	switch (itype) {
	case INSTRUM_TRACEPOINTS:
		ret = tracepoint_probe_register(name, probe, event);
		if (ret)
			goto register_error;
		break;
	default:
		WARN_ON_ONCE(1);
	}
	mutex_unlock(&sessions_mutex);
	return event;

register_error:
	kfree(event->name);
name_error:
	kmem_cache_free(event_cache, event);
cache_error:
exist:
full:
	mutex_unlock(&sessions_mutex);
	return NULL;
}

/*
 * Only used internally at session destruction.
 */
int _ltt_event_destroy(struct ltt_event *event)
{
	int ret = -EINVAL;

	switch (event->itype) {
	case INSTRUM_TRACEPOINTS:
		ret = tracepoint_probe_unregister(event->name, event->probe,
						  event);
		if (ret)
			return ret;
		break;
	default:
		WARN_ON_ONCE(1);
	}
	kfree(event->name);
	kmem_cache_free(event_cache, event);
	return ret;
}

/**
 * ltt_transport_register - LTT transport registration
 * @transport: transport structure
 *
 * Registers a transport which can be used as output to extract the data out of
 * LTTng. The module calling this registration function must ensure that no
 * trap-inducing code will be executed by the transport functions. E.g.
 * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
 * is made visible to the transport function. This registration acts as a
 * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
 * after its registration must it synchronize the TLBs.
 */
void ltt_transport_register(struct ltt_transport *transport)
{
	/*
	 * Make sure no page fault can be triggered by the module about to be
	 * registered. We deal with this here so we don't have to call
	 * vmalloc_sync_all() in each module's init.
	 */
	vmalloc_sync_all();

	mutex_lock(&sessions_mutex);
	list_add_tail(&transport->node, &ltt_transport_list);
	mutex_unlock(&sessions_mutex);
}
EXPORT_SYMBOL_GPL(ltt_transport_register);

/**
 * ltt_transport_unregister - LTT transport unregistration
 * @transport: transport structure
 */
void ltt_transport_unregister(struct ltt_transport *transport)
{
	mutex_lock(&sessions_mutex);
	list_del(&transport->node);
	mutex_unlock(&sessions_mutex);
}
EXPORT_SYMBOL_GPL(ltt_transport_unregister);


static int __init ltt_events_init(void)
{
	int ret;

	event_cache = KMEM_CACHE(ltt_event, 0);
	if (!event_cache)
		return -ENOMEM;
	ret = ltt_debugfs_abi_init();
	if (ret)
		goto error;
	return 0;
error:
	kmem_cache_destroy(event_cache);
	return ret;
}

module_init(ltt_events_init);

static void __exit ltt_events_exit(void)
{
	struct ltt_session *session, *tmpsession;

	ltt_debugfs_abi_exit();
	list_for_each_entry_safe(session, tmpsession, &sessions, list)
		ltt_session_destroy(session);
	kmem_cache_destroy(event_cache);
}

module_exit(ltt_events_exit);

MODULE_LICENSE("GPL and additional rights");
MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
MODULE_DESCRIPTION("LTTng Events");
Commit	Line	Data
	1	/*
	2	* ltt-events.c
	3	*
	4	* Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	5	*
	6	* Holds LTTng per-session event registry.
	7	*/
	8
	9	#include <linux/module.h>
	10	#include <linux/list.h>
	11	#include <linux/mutex.h>
	12	#include <linux/sched.h>
	13	#include <linux/slab.h>
	14	#include <linux/vmalloc.h> /* For vmalloc_sync_all */
	15	#include "ltt-events.h"
	16
	17	static LIST_HEAD(sessions);
	18	static LIST_HEAD(ltt_transport_list);
	19	static DEFINE_MUTEX(sessions_mutex);
	20	static struct kmem_cache *event_cache;
	21
	22	static void synchronize_trace(void)
	23	{
	24	synchronize_sched();
	25	#ifdef CONFIG_PREEMPT_RT
	26	synchronize_rcu();
	27	#endif
	28	}
	29
	30	struct ltt_session *ltt_session_create(void)
	31	{
	32	struct ltt_session *session;
	33
	34	mutex_lock(&sessions_mutex);
	35	session = kzalloc(sizeof(struct ltt_session), GFP_KERNEL);
	36	if (!session)
	37	return NULL;
	38	INIT_LIST_HEAD(&session->chan);
	39	INIT_LIST_HEAD(&session->events);
	40	list_add(&session->list, &sessions);
	41	mutex_unlock(&sessions_mutex);
	42	return session;
	43	}
	44
	45	void ltt_session_destroy(struct ltt_session *session)
	46	{
	47	struct ltt_channel chan, tmpchan;
	48	struct ltt_event event, tmpevent;
	49
	50	mutex_lock(&sessions_mutex);
	51	session->active = 0;
	52	synchronize_trace(); /* Wait for in-flight events to complete */
	53	list_for_each_entry_safe(event, tmpevent, &session->events, list)
	54	_ltt_event_destroy(event);
	55	list_for_each_entry_safe(chan, tmpchan, &session->chan, list)
	56	_ltt_channel_destroy(chan);
	57	list_del(&session->list);
	58	mutex_unlock(&sessions_mutex);
	59	kfree(session);
	60	}
	61
	62	int ltt_session_start(struct ltt_session *session)
	63	{
	64	int ret = 0;
	65
	66	mutex_lock(&sessions_mutex);
	67	if (session->active) {
	68	ret = -EBUSY;
	69	goto end;
	70	}
	71	session->active = 1;
	72	synchronize_trace(); /* Wait for in-flight events to complete */
	73	end:
	74	mutex_unlock(&sessions_mutex);
	75	return ret;
	76	}
	77
	78	int ltt_session_stop(struct ltt_session *session)
	79	{
	80	int ret = 0;
	81
	82	mutex_lock(&sessions_mutex);
	83	if (!session->active) {
	84	ret = -EBUSY;
	85	goto end;
	86	}
	87	session->active = 0;
	88	synchronize_trace(); /* Wait for in-flight events to complete */
	89	end:
	90	mutex_unlock(&sessions_mutex);
	91	return ret;
	92	}
	93
	94	static struct ltt_transport ltt_transport_find(char name)
	95	{
	96	struct ltt_transport *transport;
	97
	98	list_for_each_entry(transport, &ltt_transport_list, node) {
	99	if (!strcmp(transport->name, name))
	100	return transport;
	101	}
	102	return NULL;
	103	}
	104
	105	struct ltt_channel ltt_channel_create(struct ltt_session session,
	106	int overwrite, void *buf_addr,
	107	size_t subbuf_size, size_t num_subbuf,
	108	unsigned int switch_timer_interval,
	109	unsigned int read_timer_interval)
	110	{
	111	struct ltt_channel *chan;
	112	struct ltt_transport *transport;
	113	char *transport_name;
	114
	115	mutex_lock(&sessions_mutex);
	116	if (session->active) {
	117	printk(KERN_WARNING "LTTng refusing to add channel to active session\n");
	118	goto active; /* Refuse to add channel to active session */
	119	}
	120	transport_name = overwrite ? "relay-overwrite" : "relay-discard";
	121	transport = ltt_transport_find(transport_name);
	122	if (!transport) {
	123	printk(KERN_WARNING "LTTng transport %s not found\n",
	124	transport_name);
	125	goto notransport;
	126	}
	127	printk("got transport\n");
	128	chan = kzalloc(sizeof(struct ltt_channel), GFP_KERNEL);
	129	if (!chan)
	130	goto nomem;
	131	chan->session = session;
	132	init_waitqueue_head(&chan->notify_wait);
	133	chan->chan = transport->ops.channel_create("[lttng]", session, buf_addr,
	134	subbuf_size, num_subbuf, switch_timer_interval,
	135	read_timer_interval);
	136	printk("chan create %p\n", chan->chan);
	137	if (!chan->chan)
	138	goto create_error;
	139	chan->ops = &transport->ops;
	140	list_add(&chan->list, &session->chan);
	141	mutex_unlock(&sessions_mutex);
	142	return chan;
	143
	144	create_error:
	145	kfree(chan);
	146	nomem:
	147	notransport:
	148	active:
	149	mutex_unlock(&sessions_mutex);
	150	return NULL;
	151	}
	152
	153	/*
	154	* Only used internally at session destruction.
	155	*/
	156	void _ltt_channel_destroy(struct ltt_channel *chan)
	157	{
	158	chan->ops->channel_destroy(chan->chan);
	159	list_del(&chan->list);
	160	kfree(chan);
	161	}
	162
	163	/*
	164	* Supports event creation while tracing session is active.
	165	*/
	166	struct ltt_event ltt_event_create(struct ltt_channel chan, char *name,
	167	enum instrum_type itype,
	168	void probe, void filter)
	169	{
	170	struct ltt_event *event;
	171	int ret;
	172
	173	mutex_lock(&sessions_mutex);
	174	if (chan->free_event_id == -1UL)
	175	goto full;
	176	/*
	177	* This is O(n^2) (for each event loop called at event creation).
	178	* Might require a hash if we have lots of events.
	179	*/
	180	list_for_each_entry(event, &chan->session->events, list)
	181	if (!strcmp(event->name, name))
	182	goto exist;
	183	event = kmem_cache_zalloc(event_cache, GFP_KERNEL);
	184	if (!event)
	185	goto cache_error;
	186	event->name = kmalloc(strlen(name) + 1, GFP_KERNEL);
	187	if (!event->name)
	188	goto name_error;
	189	strcpy(event->name, name);
	190	event->chan = chan;
	191	event->probe = probe;
	192	event->filter = filter;
	193	event->id = chan->free_event_id++;
	194	event->itype = itype;
	195	/* Populate ltt_event structure before tracepoint registration. */
	196	smp_wmb();
	197	switch (itype) {
	198	case INSTRUM_TRACEPOINTS:
	199	ret = tracepoint_probe_register(name, probe, event);
	200	if (ret)
	201	goto register_error;
	202	break;
	203	default:
	204	WARN_ON_ONCE(1);
	205	}
	206	mutex_unlock(&sessions_mutex);
	207	return event;
	208
	209	register_error:
	210	kfree(event->name);
	211	name_error:
	212	kmem_cache_free(event_cache, event);
	213	cache_error:
	214	exist:
	215	full:
	216	mutex_unlock(&sessions_mutex);
	217	return NULL;
	218	}
	219
	220	/*
	221	* Only used internally at session destruction.
	222	*/
	223	int _ltt_event_destroy(struct ltt_event *event)
	224	{
	225	int ret = -EINVAL;
	226
	227	switch (event->itype) {
	228	case INSTRUM_TRACEPOINTS:
	229	ret = tracepoint_probe_unregister(event->name, event->probe,
	230	event);
	231	if (ret)
	232	return ret;
	233	break;
	234	default:
	235	WARN_ON_ONCE(1);
	236	}
	237	kfree(event->name);
	238	kmem_cache_free(event_cache, event);
	239	return ret;
	240	}
	241
	242	/**
	243	* ltt_transport_register - LTT transport registration
	244	* @transport: transport structure
	245	*
	246	* Registers a transport which can be used as output to extract the data out of
	247	* LTTng. The module calling this registration function must ensure that no
	248	* trap-inducing code will be executed by the transport functions. E.g.
	249	* vmalloc_sync_all() must be called between a vmalloc and the moment the memory
	250	* is made visible to the transport function. This registration acts as a
	251	* vmalloc_sync_all. Therefore, only if the module allocates virtual memory
	252	* after its registration must it synchronize the TLBs.
	253	*/
	254	void ltt_transport_register(struct ltt_transport *transport)
	255	{
	256	/*
	257	* Make sure no page fault can be triggered by the module about to be
	258	* registered. We deal with this here so we don't have to call
	259	* vmalloc_sync_all() in each module's init.
	260	*/
	261	vmalloc_sync_all();
	262
	263	mutex_lock(&sessions_mutex);
	264	list_add_tail(&transport->node, &ltt_transport_list);
	265	mutex_unlock(&sessions_mutex);
	266	}
	267	EXPORT_SYMBOL_GPL(ltt_transport_register);
	268
	269	/**
	270	* ltt_transport_unregister - LTT transport unregistration
	271	* @transport: transport structure
	272	*/
	273	void ltt_transport_unregister(struct ltt_transport *transport)
	274	{
	275	mutex_lock(&sessions_mutex);
	276	list_del(&transport->node);
	277	mutex_unlock(&sessions_mutex);
	278	}
	279	EXPORT_SYMBOL_GPL(ltt_transport_unregister);
	280
	281
	282	static int __init ltt_events_init(void)
	283	{
	284	int ret;
	285
	286	event_cache = KMEM_CACHE(ltt_event, 0);
	287	if (!event_cache)
	288	return -ENOMEM;
	289	ret = ltt_debugfs_abi_init();
	290	if (ret)
	291	goto error;
	292	return 0;
	293	error:
	294	kmem_cache_destroy(event_cache);
	295	return ret;
	296	}
	297
	298	module_init(ltt_events_init);
	299
	300	static void __exit ltt_events_exit(void)
	301	{
	302	struct ltt_session session, tmpsession;
	303
	304	ltt_debugfs_abi_exit();
	305	list_for_each_entry_safe(session, tmpsession, &sessions, list)
	306	ltt_session_destroy(session);
	307	kmem_cache_destroy(event_cache);
	308	}
	309
	310	module_exit(ltt_events_exit);
	311
	312	MODULE_LICENSE("GPL and additional rights");
	313	MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
	314	MODULE_DESCRIPTION("LTTng Events");