[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 "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;
	init_waitqueue_head(&chan->notify_wait);

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