[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;
	}
	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);
	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_probes_init();
	if (ret)
		goto error;
	ret = ltt_debugfs_abi_init();
	if (ret)
		goto error_abi;
	return 0;
error_abi:
	ltt_probes_exit();
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();
	ltt_probes_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);
f3d01b96	35	session = kzalloc(sizeof(struct ltt_session), GFP_KERNEL);
4e3c1b9b MD	36	if (!session)
4e3c1b9b MD	37	return NULL;
4e3c1b9b	38	INIT_LIST_HEAD(&session->chan);
f3d01b96	39	INIT_LIST_HEAD(&session->events);
4e3c1b9b MD	40	list_add(&session->list, &sessions);
	41	mutex_unlock(&sessions_mutex);
	42	return session;
4e3c1b9b MD	43	}
4e3c1b9b MD	44
11b5a3c2	45	void ltt_session_destroy(struct ltt_session *session)
4e3c1b9b MD	46	{
	47	struct ltt_channel chan, tmpchan;
	48	struct ltt_event event, tmpevent;
	49
	50	mutex_lock(&sessions_mutex);
abcca994 MD	51	session->active = 0;
abcca994 MD	52	synchronize_trace(); /* Wait for in-flight events to complete */
4e3c1b9b MD	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
c0e31d2e MD	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);
11b5a3c2	75	return ret;
c0e31d2e MD	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);
11b5a3c2	91	return ret;
c0e31d2e MD	92	}
c0e31d2e MD	93
f3d01b96 MD	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
baf20995	105	struct ltt_channel ltt_channel_create(struct ltt_session session,
4e3c1b9b MD	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;
f3d01b96	112	struct ltt_transport *transport;
c0e31d2e	113	char *transport_name;
4e3c1b9b MD	114
4e3c1b9b MD	115	mutex_lock(&sessions_mutex);
f3d01b96 MD	116	if (session->active) {
f3d01b96 MD	117	printk(KERN_WARNING "LTTng refusing to add channel to active session\n");
e5382b6d	118	goto active; /* Refuse to add channel to active session */
c0e31d2e	119	}
f3d01b96 MD	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);
c0e31d2e	125	goto notransport;
f3d01b96	126	}
f3d01b96	127	chan = kzalloc(sizeof(struct ltt_channel), GFP_KERNEL);
4e3c1b9b	128	if (!chan)
c0e31d2e	129	goto nomem;
4e3c1b9b	130	chan->session = session;
653fe716	131	init_waitqueue_head(&chan->notify_wait);
11b5a3c2 MD	132	chan->chan = transport->ops.channel_create("[lttng]", session, buf_addr,
	133	subbuf_size, num_subbuf, switch_timer_interval,
	134	read_timer_interval);
f3d01b96 MD	135	if (!chan->chan)
f3d01b96 MD	136	goto create_error;
11b5a3c2	137	chan->ops = &transport->ops;
4e3c1b9b MD	138	list_add(&chan->list, &session->chan);
	139	mutex_unlock(&sessions_mutex);
	140	return chan;
	141
f3d01b96 MD	142	create_error:
f3d01b96 MD	143	kfree(chan);
c0e31d2e MD	144	nomem:
c0e31d2e MD	145	notransport:
e5382b6d	146	active:
4e3c1b9b MD	147	mutex_unlock(&sessions_mutex);
	148	return NULL;
	149	}
	150
	151	/*
	152	* Only used internally at session destruction.
	153	*/
11b5a3c2	154	void _ltt_channel_destroy(struct ltt_channel *chan)
4e3c1b9b	155	{
11b5a3c2	156	chan->ops->channel_destroy(chan->chan);
4e3c1b9b MD	157	list_del(&chan->list);
	158	kfree(chan);
	159	}
	160
e5382b6d MD	161	/*
	162	* Supports event creation while tracing session is active.
	163	*/
4e3c1b9b	164	struct ltt_event ltt_event_create(struct ltt_channel chan, char *name,
baf20995 MD	165	enum instrum_type itype,
baf20995 MD	166	void probe, void filter)
4e3c1b9b MD	167	{
4e3c1b9b MD	168	struct ltt_event *event;
3d084699	169	int ret;
4e3c1b9b MD	170
4e3c1b9b MD	171	mutex_lock(&sessions_mutex);
e5382b6d MD	172	if (chan->free_event_id == -1UL)
e5382b6d MD	173	goto full;
4e3c1b9b MD	174	/*
	175	* This is O(n^2) (for each event loop called at event creation).
	176	* Might require a hash if we have lots of events.
	177	*/
	178	list_for_each_entry(event, &chan->session->events, list)
	179	if (!strcmp(event->name, name))
	180	goto exist;
11b5a3c2	181	event = kmem_cache_zalloc(event_cache, GFP_KERNEL);
4e3c1b9b MD	182	if (!event)
	183	goto cache_error;
	184	event->name = kmalloc(strlen(name) + 1, GFP_KERNEL);
	185	if (!event->name)
11b5a3c2	186	goto name_error;
4e3c1b9b MD	187	strcpy(event->name, name);
4e3c1b9b MD	188	event->chan = chan;
baf20995	189	event->probe = probe;
4e3c1b9b	190	event->filter = filter;
e5382b6d	191	event->id = chan->free_event_id++;
baf20995	192	event->itype = itype;
e5382b6d MD	193	/* Populate ltt_event structure before tracepoint registration. */
e5382b6d MD	194	smp_wmb();
baf20995 MD	195	switch (itype) {
	196	case INSTRUM_TRACEPOINTS:
	197	ret = tracepoint_probe_register(name, probe, event);
11b5a3c2 MD	198	if (ret)
11b5a3c2 MD	199	goto register_error;
baf20995 MD	200	break;
	201	default:
	202	WARN_ON_ONCE(1);
	203	}
11b5a3c2	204	mutex_unlock(&sessions_mutex);
4e3c1b9b MD	205	return event;
4e3c1b9b MD	206
11b5a3c2 MD	207	register_error:
	208	kfree(event->name);
	209	name_error:
	210	kmem_cache_free(event_cache, event);
4e3c1b9b MD	211	cache_error:
4e3c1b9b MD	212	exist:
e5382b6d	213	full:
4e3c1b9b MD	214	mutex_unlock(&sessions_mutex);
	215	return NULL;
	216	}
	217
	218	/*
	219	* Only used internally at session destruction.
	220	*/
	221	int _ltt_event_destroy(struct ltt_event *event)
	222	{
11b5a3c2 MD	223	int ret = -EINVAL;
11b5a3c2 MD	224
baf20995 MD	225	switch (event->itype) {
baf20995 MD	226	case INSTRUM_TRACEPOINTS:
11b5a3c2 MD	227	ret = tracepoint_probe_unregister(event->name, event->probe,
	228	event);
	229	if (ret)
	230	return ret;
baf20995 MD	231	break;
	232	default:
	233	WARN_ON_ONCE(1);
	234	}
4e3c1b9b	235	kfree(event->name);
11b5a3c2 MD	236	kmem_cache_free(event_cache, event);
11b5a3c2 MD	237	return ret;
4e3c1b9b MD	238	}
4e3c1b9b MD	239
c0e31d2e MD	240	/**
	241	* ltt_transport_register - LTT transport registration
	242	* @transport: transport structure
	243	*
	244	* Registers a transport which can be used as output to extract the data out of
	245	* LTTng. The module calling this registration function must ensure that no
	246	* trap-inducing code will be executed by the transport functions. E.g.
	247	* vmalloc_sync_all() must be called between a vmalloc and the moment the memory
	248	* is made visible to the transport function. This registration acts as a
	249	* vmalloc_sync_all. Therefore, only if the module allocates virtual memory
	250	* after its registration must it synchronize the TLBs.
	251	*/
	252	void ltt_transport_register(struct ltt_transport *transport)
	253	{
	254	/*
	255	* Make sure no page fault can be triggered by the module about to be
	256	* registered. We deal with this here so we don't have to call
	257	* vmalloc_sync_all() in each module's init.
	258	*/
	259	vmalloc_sync_all();
	260
	261	mutex_lock(&sessions_mutex);
	262	list_add_tail(&transport->node, &ltt_transport_list);
	263	mutex_unlock(&sessions_mutex);
	264	}
	265	EXPORT_SYMBOL_GPL(ltt_transport_register);
	266
	267	/**
	268	* ltt_transport_unregister - LTT transport unregistration
	269	* @transport: transport structure
	270	*/
	271	void ltt_transport_unregister(struct ltt_transport *transport)
	272	{
	273	mutex_lock(&sessions_mutex);
	274	list_del(&transport->node);
	275	mutex_unlock(&sessions_mutex);
	276	}
	277	EXPORT_SYMBOL_GPL(ltt_transport_unregister);
	278
	279
4e3c1b9b MD	280	static int __init ltt_events_init(void)
4e3c1b9b MD	281	{
1c25284c MD	282	int ret;
1c25284c MD	283
11b5a3c2 MD	284	event_cache = KMEM_CACHE(ltt_event, 0);
11b5a3c2 MD	285	if (!event_cache)
4e3c1b9b	286	return -ENOMEM;
02119ee5	287	ret = ltt_probes_init();
1c25284c MD	288	if (ret)
1c25284c MD	289	goto error;
02119ee5 MD	290	ret = ltt_debugfs_abi_init();
	291	if (ret)
	292	goto error_abi;
4e3c1b9b	293	return 0;
02119ee5 MD	294	error_abi:
02119ee5 MD	295	ltt_probes_exit();
1c25284c MD	296	error:
	297	kmem_cache_destroy(event_cache);
	298	return ret;
4e3c1b9b MD	299	}
4e3c1b9b MD	300
11b5a3c2 MD	301	module_init(ltt_events_init);
11b5a3c2 MD	302
4e3c1b9b MD	303	static void __exit ltt_events_exit(void)
4e3c1b9b MD	304	{
92e94819 MD	305	struct ltt_session session, tmpsession;
92e94819 MD	306
1c25284c	307	ltt_debugfs_abi_exit();
02119ee5	308	ltt_probes_exit();
92e94819 MD	309	list_for_each_entry_safe(session, tmpsession, &sessions, list)
92e94819 MD	310	ltt_session_destroy(session);
11b5a3c2	311	kmem_cache_destroy(event_cache);
4e3c1b9b	312	}
92e94819	313
11b5a3c2 MD	314	module_exit(ltt_events_exit);
11b5a3c2 MD	315
92e94819 MD	316	MODULE_LICENSE("GPL and additional rights");
	317	MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
	318	MODULE_DESCRIPTION("LTTng Events");