[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 "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));
	if (!session)
		return NULL;
	INIT_LIST_HEAD(&session->chan);
	list_add(&session->list, &sessions);
	mutex_unlock(&sessions_mutex);
	return session;

exist:
	mutex_unlock(&sessions_mutex);
	return NULL;
}

int 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);
	transport->ops.channel_create(session, buf_addr, subbuf_size,
				      num_subbuf, switch_timer_interval,
				      read_timer_interval);
	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.
 */
int _ltt_channel_destroy(struct ltt_channel *chan)
{
	transport->ops.channel_destroy(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(events_cache, GFP_KERNEL);
	if (!event)
		goto cache_error;
	event->name = kmalloc(strlen(name) + 1, GFP_KERNEL);
	if (!event->name)
		goto error;
	strcpy(event->name, name);
	event->chan = chan;
	event->probe = probe;
	event->filter = filter;
	event->id = chan->free_event_id++;
	event->itype = itype;
	mutex_unlock(&sessions_mutex);
	/* Populate ltt_event structure before tracepoint registration. */
	smp_wmb();
	switch (itype) {
	case INSTRUM_TRACEPOINTS:
		ret = tracepoint_probe_register(name, probe, event);
		break;
	default:
		WARN_ON_ONCE(1);
	}
	return event;

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

/**
 * 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;

	events_cache = KMEM_CACHE(ltt_event, 0);
	if (!events_cache)
		return -ENOMEM;
	return 0;
}

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

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

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