[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 = kmalloc(sizeof(struct ltt_session), GFP_KERNEL);
	if (!session)
		return NULL;
	INIT_LIST_HEAD(&session->chan);
	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;
}

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 = NULL, *tran_iter;
	char *transport_name;

	mutex_lock(&sessions_mutex);
	if (session->active)
		goto active;	/* Refuse to add channel to active session */
	transport_name = overwrite ? "relay-overwrite" : "relay-discard";
	list_for_each_entry(tran_iter, &ltt_transport_list, node) {
		if (!strcmp(tran_iter->name, transport_name)) {
			transport = tran_iter;
			break;
		}
	}
	if (!transport)
		goto notransport;
	chan = kmalloc(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);
	chan->ops = &transport->ops;
	list_add(&chan->list, &session->chan);
	mutex_unlock(&sessions_mutex);
	return 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
4e3c1b9b MD	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>
c0e31d2e MD	10	#include <linux/list.h>
	11	#include <linux/mutex.h>
	12	#include <linux/sched.h>
11b5a3c2 MD	13	#include <linux/slab.h>
11b5a3c2 MD	14	#include <linux/vmalloc.h> /* For vmalloc_sync_all */
4e3c1b9b MD	15	#include "ltt-events.h"
	16
	17	static LIST_HEAD(sessions);
c0e31d2e	18	static LIST_HEAD(ltt_transport_list);
4e3c1b9b MD	19	static DEFINE_MUTEX(sessions_mutex);
	20	static struct kmem_cache *event_cache;
	21
abcca994 MD	22	static void synchronize_trace(void)
	23	{
	24	synchronize_sched();
	25	#ifdef CONFIG_PREEMPT_RT
	26	synchronize_rcu();
	27	#endif
	28	}
	29
baf20995	30	struct ltt_session *ltt_session_create(void)
4e3c1b9b MD	31	{
	32	struct ltt_session *session;
	33
	34	mutex_lock(&sessions_mutex);
11b5a3c2	35	session = kmalloc(sizeof(struct ltt_session), GFP_KERNEL);
4e3c1b9b MD	36	if (!session)
4e3c1b9b MD	37	return NULL;
4e3c1b9b MD	38	INIT_LIST_HEAD(&session->chan);
	39	list_add(&session->list, &sessions);
	40	mutex_unlock(&sessions_mutex);
	41	return session;
4e3c1b9b MD	42	}
4e3c1b9b MD	43
11b5a3c2	44	void ltt_session_destroy(struct ltt_session *session)
4e3c1b9b MD	45	{
	46	struct ltt_channel chan, tmpchan;
	47	struct ltt_event event, tmpevent;
	48
	49	mutex_lock(&sessions_mutex);
abcca994 MD	50	session->active = 0;
abcca994 MD	51	synchronize_trace(); /* Wait for in-flight events to complete */
4e3c1b9b MD	52	list_for_each_entry_safe(event, tmpevent, &session->events, list)
	53	_ltt_event_destroy(event);
	54	list_for_each_entry_safe(chan, tmpchan, &session->chan, list)
	55	_ltt_channel_destroy(chan);
	56	list_del(&session->list);
	57	mutex_unlock(&sessions_mutex);
	58	kfree(session);
	59	}
	60
c0e31d2e MD	61	int ltt_session_start(struct ltt_session *session)
	62	{
	63	int ret = 0;
	64
	65	mutex_lock(&sessions_mutex);
	66	if (session->active) {
	67	ret = -EBUSY;
	68	goto end;
	69	}
	70	session->active = 1;
	71	synchronize_trace(); /* Wait for in-flight events to complete */
	72	end:
	73	mutex_unlock(&sessions_mutex);
11b5a3c2	74	return ret;
c0e31d2e MD	75	}
	76
	77	int ltt_session_stop(struct ltt_session *session)
	78	{
	79	int ret = 0;
	80
	81	mutex_lock(&sessions_mutex);
	82	if (!session->active) {
	83	ret = -EBUSY;
	84	goto end;
	85	}
	86	session->active = 0;
	87	synchronize_trace(); /* Wait for in-flight events to complete */
	88	end:
	89	mutex_unlock(&sessions_mutex);
11b5a3c2	90	return ret;
c0e31d2e MD	91	}
c0e31d2e MD	92
baf20995	93	struct ltt_channel ltt_channel_create(struct ltt_session session,
4e3c1b9b MD	94	int overwrite, void *buf_addr,
	95	size_t subbuf_size, size_t num_subbuf,
	96	unsigned int switch_timer_interval,
	97	unsigned int read_timer_interval)
	98	{
	99	struct ltt_channel *chan;
c0e31d2e MD	100	struct ltt_transport transport = NULL, tran_iter;
c0e31d2e MD	101	char *transport_name;
4e3c1b9b MD	102
4e3c1b9b MD	103	mutex_lock(&sessions_mutex);
e5382b6d MD	104	if (session->active)
e5382b6d MD	105	goto active; /* Refuse to add channel to active session */
c0e31d2e MD	106	transport_name = overwrite ? "relay-overwrite" : "relay-discard";
	107	list_for_each_entry(tran_iter, &ltt_transport_list, node) {
	108	if (!strcmp(tran_iter->name, transport_name)) {
	109	transport = tran_iter;
	110	break;
	111	}
	112	}
	113	if (!transport)
	114	goto notransport;
baf20995	115	chan = kmalloc(sizeof(struct ltt_channel), GFP_KERNEL);
4e3c1b9b	116	if (!chan)
c0e31d2e	117	goto nomem;
4e3c1b9b	118	chan->session = session;
653fe716	119	init_waitqueue_head(&chan->notify_wait);
11b5a3c2 MD	120	chan->chan = transport->ops.channel_create("[lttng]", session, buf_addr,
	121	subbuf_size, num_subbuf, switch_timer_interval,
	122	read_timer_interval);
	123	chan->ops = &transport->ops;
4e3c1b9b MD	124	list_add(&chan->list, &session->chan);
	125	mutex_unlock(&sessions_mutex);
	126	return chan;
	127
c0e31d2e MD	128	nomem:
c0e31d2e MD	129	notransport:
e5382b6d	130	active:
4e3c1b9b MD	131	mutex_unlock(&sessions_mutex);
	132	return NULL;
	133	}
	134
	135	/*
	136	* Only used internally at session destruction.
	137	*/
11b5a3c2	138	void _ltt_channel_destroy(struct ltt_channel *chan)
4e3c1b9b	139	{
11b5a3c2	140	chan->ops->channel_destroy(chan->chan);
4e3c1b9b MD	141	list_del(&chan->list);
	142	kfree(chan);
	143	}
	144
e5382b6d MD	145	/*
	146	* Supports event creation while tracing session is active.
	147	*/
4e3c1b9b	148	struct ltt_event ltt_event_create(struct ltt_channel chan, char *name,
baf20995 MD	149	enum instrum_type itype,
baf20995 MD	150	void probe, void filter)
4e3c1b9b MD	151	{
4e3c1b9b MD	152	struct ltt_event *event;
3d084699	153	int ret;
4e3c1b9b MD	154
4e3c1b9b MD	155	mutex_lock(&sessions_mutex);
e5382b6d MD	156	if (chan->free_event_id == -1UL)
e5382b6d MD	157	goto full;
4e3c1b9b MD	158	/*
	159	* This is O(n^2) (for each event loop called at event creation).
	160	* Might require a hash if we have lots of events.
	161	*/
	162	list_for_each_entry(event, &chan->session->events, list)
	163	if (!strcmp(event->name, name))
	164	goto exist;
11b5a3c2	165	event = kmem_cache_zalloc(event_cache, GFP_KERNEL);
4e3c1b9b MD	166	if (!event)
	167	goto cache_error;
	168	event->name = kmalloc(strlen(name) + 1, GFP_KERNEL);
	169	if (!event->name)
11b5a3c2	170	goto name_error;
4e3c1b9b MD	171	strcpy(event->name, name);
4e3c1b9b MD	172	event->chan = chan;
baf20995	173	event->probe = probe;
4e3c1b9b	174	event->filter = filter;
e5382b6d	175	event->id = chan->free_event_id++;
baf20995	176	event->itype = itype;
e5382b6d MD	177	/* Populate ltt_event structure before tracepoint registration. */
e5382b6d MD	178	smp_wmb();
baf20995 MD	179	switch (itype) {
	180	case INSTRUM_TRACEPOINTS:
	181	ret = tracepoint_probe_register(name, probe, event);
11b5a3c2 MD	182	if (ret)
11b5a3c2 MD	183	goto register_error;
baf20995 MD	184	break;
	185	default:
	186	WARN_ON_ONCE(1);
	187	}
11b5a3c2	188	mutex_unlock(&sessions_mutex);
4e3c1b9b MD	189	return event;
4e3c1b9b MD	190
11b5a3c2 MD	191	register_error:
	192	kfree(event->name);
	193	name_error:
	194	kmem_cache_free(event_cache, event);
4e3c1b9b MD	195	cache_error:
4e3c1b9b MD	196	exist:
e5382b6d	197	full:
4e3c1b9b MD	198	mutex_unlock(&sessions_mutex);
	199	return NULL;
	200	}
	201
	202	/*
	203	* Only used internally at session destruction.
	204	*/
	205	int _ltt_event_destroy(struct ltt_event *event)
	206	{
11b5a3c2 MD	207	int ret = -EINVAL;
11b5a3c2 MD	208
baf20995 MD	209	switch (event->itype) {
baf20995 MD	210	case INSTRUM_TRACEPOINTS:
11b5a3c2 MD	211	ret = tracepoint_probe_unregister(event->name, event->probe,
	212	event);
	213	if (ret)
	214	return ret;
baf20995 MD	215	break;
	216	default:
	217	WARN_ON_ONCE(1);
	218	}
4e3c1b9b	219	kfree(event->name);
11b5a3c2 MD	220	kmem_cache_free(event_cache, event);
11b5a3c2 MD	221	return ret;
4e3c1b9b MD	222	}
4e3c1b9b MD	223
c0e31d2e MD	224	/**
	225	* ltt_transport_register - LTT transport registration
	226	* @transport: transport structure
	227	*
	228	* Registers a transport which can be used as output to extract the data out of
	229	* LTTng. The module calling this registration function must ensure that no
	230	* trap-inducing code will be executed by the transport functions. E.g.
	231	* vmalloc_sync_all() must be called between a vmalloc and the moment the memory
	232	* is made visible to the transport function. This registration acts as a
	233	* vmalloc_sync_all. Therefore, only if the module allocates virtual memory
	234	* after its registration must it synchronize the TLBs.
	235	*/
	236	void ltt_transport_register(struct ltt_transport *transport)
	237	{
	238	/*
	239	* Make sure no page fault can be triggered by the module about to be
	240	* registered. We deal with this here so we don't have to call
	241	* vmalloc_sync_all() in each module's init.
	242	*/
	243	vmalloc_sync_all();
	244
	245	mutex_lock(&sessions_mutex);
	246	list_add_tail(&transport->node, &ltt_transport_list);
	247	mutex_unlock(&sessions_mutex);
	248	}
	249	EXPORT_SYMBOL_GPL(ltt_transport_register);
	250
	251	/**
	252	* ltt_transport_unregister - LTT transport unregistration
	253	* @transport: transport structure
	254	*/
	255	void ltt_transport_unregister(struct ltt_transport *transport)
	256	{
	257	mutex_lock(&sessions_mutex);
	258	list_del(&transport->node);
	259	mutex_unlock(&sessions_mutex);
	260	}
	261	EXPORT_SYMBOL_GPL(ltt_transport_unregister);
	262
	263
4e3c1b9b MD	264	static int __init ltt_events_init(void)
4e3c1b9b MD	265	{
1c25284c MD	266	int ret;
1c25284c MD	267
11b5a3c2 MD	268	event_cache = KMEM_CACHE(ltt_event, 0);
11b5a3c2 MD	269	if (!event_cache)
4e3c1b9b	270	return -ENOMEM;
1c25284c MD	271	ret = ltt_debugfs_abi_init();
	272	if (ret)
	273	goto error;
4e3c1b9b	274	return 0;
1c25284c MD	275	error:
	276	kmem_cache_destroy(event_cache);
	277	return ret;
4e3c1b9b MD	278	}
4e3c1b9b MD	279
11b5a3c2 MD	280	module_init(ltt_events_init);
11b5a3c2 MD	281
4e3c1b9b MD	282	static void __exit ltt_events_exit(void)
4e3c1b9b MD	283	{
92e94819 MD	284	struct ltt_session session, tmpsession;
92e94819 MD	285
1c25284c	286	ltt_debugfs_abi_exit();
92e94819 MD	287	list_for_each_entry_safe(session, tmpsession, &sessions, list)
92e94819 MD	288	ltt_session_destroy(session);
11b5a3c2	289	kmem_cache_destroy(event_cache);
4e3c1b9b	290	}
92e94819	291
11b5a3c2 MD	292	module_exit(ltt_events_exit);
11b5a3c2 MD	293
92e94819 MD	294	MODULE_LICENSE("GPL and additional rights");
	295	MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
	296	MODULE_DESCRIPTION("LTTng Events");