[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 "ltt-events.h"

static LIST_HEAD(sessions);
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);
}

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;

	mutex_lock(&sessions_mutex);
	if (session->active)
		goto active;	/* Refuse to add channel to active session */
	chan = kmalloc(sizeof(struct ltt_channel), GFP_KERNEL);
	if (!chan)
		return NULL;
	chan->session = session;

	/* TODO: create rb channel */
	list_add(&chan->list, &session->chan);
	mutex_unlock(&sessions_mutex);
	return chan;

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

/*
 * Only used internally at session destruction.
 */
int _ltt_channel_destroy(struct ltt_channel *chan)
{
	/* TODO: destroy rb channel */
	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);
}

static int __init ltt_events_init(void)
{
	int ret;

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

	/* TODO: show ABI to userspace */

	return 0;
}

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

	/* TODO: hide ABI from userspace, wait for callers to release refs. */

	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>
	10	#include "ltt-events.h"
	11
	12	static LIST_HEAD(sessions);
	13	static DEFINE_MUTEX(sessions_mutex);
	14	static struct kmem_cache *event_cache;
	15
abcca994 MD	16	static void synchronize_trace(void)
	17	{
	18	synchronize_sched();
	19	#ifdef CONFIG_PREEMPT_RT
	20	synchronize_rcu();
	21	#endif
	22	}
	23
baf20995	24	struct ltt_session *ltt_session_create(void)
4e3c1b9b MD	25	{
	26	struct ltt_session *session;
	27
	28	mutex_lock(&sessions_mutex);
baf20995	29	session = kmalloc(sizeof(struct ltt_session));
4e3c1b9b MD	30	if (!session)
4e3c1b9b MD	31	return NULL;
4e3c1b9b MD	32	INIT_LIST_HEAD(&session->chan);
	33	list_add(&session->list, &sessions);
	34	mutex_unlock(&sessions_mutex);
	35	return session;
	36
	37	exist:
	38	mutex_unlock(&sessions_mutex);
	39	return NULL;
	40	}
	41
	42	int ltt_session_destroy(struct ltt_session *session)
	43	{
	44	struct ltt_channel chan, tmpchan;
	45	struct ltt_event event, tmpevent;
	46
	47	mutex_lock(&sessions_mutex);
abcca994 MD	48	session->active = 0;
abcca994 MD	49	synchronize_trace(); /* Wait for in-flight events to complete */
4e3c1b9b MD	50	list_for_each_entry_safe(event, tmpevent, &session->events, list)
	51	_ltt_event_destroy(event);
	52	list_for_each_entry_safe(chan, tmpchan, &session->chan, list)
	53	_ltt_channel_destroy(chan);
	54	list_del(&session->list);
	55	mutex_unlock(&sessions_mutex);
	56	kfree(session);
	57	}
	58
baf20995	59	struct ltt_channel ltt_channel_create(struct ltt_session session,
4e3c1b9b MD	60	int overwrite, void *buf_addr,
	61	size_t subbuf_size, size_t num_subbuf,
	62	unsigned int switch_timer_interval,
	63	unsigned int read_timer_interval)
	64	{
	65	struct ltt_channel *chan;
	66
	67	mutex_lock(&sessions_mutex);
e5382b6d MD	68	if (session->active)
e5382b6d MD	69	goto active; /* Refuse to add channel to active session */
baf20995	70	chan = kmalloc(sizeof(struct ltt_channel), GFP_KERNEL);
4e3c1b9b MD	71	if (!chan)
4e3c1b9b MD	72	return NULL;
4e3c1b9b MD	73	chan->session = session;
	74
	75	/* TODO: create rb channel */
	76	list_add(&chan->list, &session->chan);
	77	mutex_unlock(&sessions_mutex);
	78	return chan;
	79
	80	exist:
e5382b6d	81	active:
4e3c1b9b MD	82	mutex_unlock(&sessions_mutex);
	83	return NULL;
	84	}
	85
	86	/*
	87	* Only used internally at session destruction.
	88	*/
	89	int _ltt_channel_destroy(struct ltt_channel *chan)
	90	{
abcca994	91	/* TODO: destroy rb channel */
4e3c1b9b MD	92	list_del(&chan->list);
	93	kfree(chan);
	94	}
	95
e5382b6d MD	96	/*
	97	* Supports event creation while tracing session is active.
	98	*/
4e3c1b9b	99	struct ltt_event ltt_event_create(struct ltt_channel chan, char *name,
baf20995 MD	100	enum instrum_type itype,
baf20995 MD	101	void probe, void filter)
4e3c1b9b MD	102	{
4e3c1b9b MD	103	struct ltt_event *event;
3d084699	104	int ret;
4e3c1b9b MD	105
4e3c1b9b MD	106	mutex_lock(&sessions_mutex);
e5382b6d MD	107	if (chan->free_event_id == -1UL)
e5382b6d MD	108	goto full;
4e3c1b9b MD	109	/*
	110	* This is O(n^2) (for each event loop called at event creation).
	111	* Might require a hash if we have lots of events.
	112	*/
	113	list_for_each_entry(event, &chan->session->events, list)
	114	if (!strcmp(event->name, name))
	115	goto exist;
	116	event = kmem_cache_zalloc(events_cache, GFP_KERNEL);
	117	if (!event)
	118	goto cache_error;
	119	event->name = kmalloc(strlen(name) + 1, GFP_KERNEL);
	120	if (!event->name)
	121	goto error;
	122	strcpy(event->name, name);
	123	event->chan = chan;
baf20995	124	event->probe = probe;
4e3c1b9b	125	event->filter = filter;
e5382b6d	126	event->id = chan->free_event_id++;
baf20995	127	event->itype = itype;
4e3c1b9b	128	mutex_unlock(&sessions_mutex);
e5382b6d MD	129	/* Populate ltt_event structure before tracepoint registration. */
e5382b6d MD	130	smp_wmb();
baf20995 MD	131	switch (itype) {
	132	case INSTRUM_TRACEPOINTS:
	133	ret = tracepoint_probe_register(name, probe, event);
	134	break;
	135	default:
	136	WARN_ON_ONCE(1);
	137	}
4e3c1b9b MD	138	return event;
	139
	140	error:
	141	kmem_cache_free(event);
	142	cache_error:
	143	exist:
e5382b6d	144	full:
4e3c1b9b MD	145	mutex_unlock(&sessions_mutex);
	146	return NULL;
	147	}
	148
	149	/*
	150	* Only used internally at session destruction.
	151	*/
	152	int _ltt_event_destroy(struct ltt_event *event)
	153	{
baf20995 MD	154	switch (event->itype) {
	155	case INSTRUM_TRACEPOINTS:
	156	ret = tracepoint_probe_unregister(name, event->probe, event);
	157	break;
	158	default:
	159	WARN_ON_ONCE(1);
	160	}
4e3c1b9b MD	161	kfree(event->name);
	162	kmem_cache_free(event);
	163	}
	164
	165	static int __init ltt_events_init(void)
	166	{
	167	int ret;
	168
	169	events_cache = KMEM_CACHE(ltt_event, 0);
	170	if (!events_cache)
	171	return -ENOMEM;
92e94819 MD	172
	173	/* TODO: show ABI to userspace */
	174
4e3c1b9b MD	175	return 0;
	176	}
	177
	178	static void __exit ltt_events_exit(void)
	179	{
92e94819 MD	180	struct ltt_session session, tmpsession;
	181
	182	/* TODO: hide ABI from userspace, wait for callers to release refs. */
	183
	184	list_for_each_entry_safe(session, tmpsession, &sessions, list)
	185	ltt_session_destroy(session);
4e3c1b9b MD	186	kmem_cache_destroy(events_cache);
4e3c1b9b MD	187	}
92e94819 MD	188
	189	MODULE_LICENSE("GPL and additional rights");
	190	MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
	191	MODULE_DESCRIPTION("LTTng Events");