[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(char *name)
{
	struct ltt_session *session;

	mutex_lock(&sessions_mutex);
	list_for_each_entry(session, &sessions, list)
		if (!strcmp(session->name, name))
			goto exist;
	session = kmalloc(sizeof(struct ltt_session) + strlen(name) + 1);
	if (!session)
		return NULL;
	strcpy(session->name, name);
	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, char *name,
				       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 */
	list_for_each_entry(chan, &session->chan, list)
		if (!strcmp(chan->name, name))
			goto exist;
	chan = kmalloc(sizeof(struct ltt_channel) + strlen(name) + 1, GFP_KERNEL);
	if (!chan)
		return NULL;
	strcpy(chan->name, name);
	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,
				   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->filter = filter;
	event->id = chan->free_event_id++;
	mutex_unlock(&sessions_mutex);
	/* Populate ltt_event structure before tracepoint registration. */
	smp_wmb();
	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)
{
	/* TODO unregister from tracepoint */
	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
4e3c1b9b MD	24	struct ltt_session ltt_session_create(char name)
	25	{
	26	struct ltt_session *session;
	27
	28	mutex_lock(&sessions_mutex);
	29	list_for_each_entry(session, &sessions, list)
	30	if (!strcmp(session->name, name))
	31	goto exist;
	32	session = kmalloc(sizeof(struct ltt_session) + strlen(name) + 1);
	33	if (!session)
	34	return NULL;
	35	strcpy(session->name, name);
	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
	63	struct ltt_channel ltt_channel_create(struct ltt_session session, char *name,
	64	int overwrite, void *buf_addr,
	65	size_t subbuf_size, size_t num_subbuf,
	66	unsigned int switch_timer_interval,
	67	unsigned int read_timer_interval)
	68	{
	69	struct ltt_channel *chan;
	70
	71	mutex_lock(&sessions_mutex);
e5382b6d MD	72	if (session->active)
e5382b6d MD	73	goto active; /* Refuse to add channel to active session */
4e3c1b9b MD	74	list_for_each_entry(chan, &session->chan, list)
	75	if (!strcmp(chan->name, name))
	76	goto exist;
	77	chan = kmalloc(sizeof(struct ltt_channel) + strlen(name) + 1, GFP_KERNEL);
	78	if (!chan)
	79	return NULL;
	80	strcpy(chan->name, name);
	81	chan->session = session;
	82
	83	/* TODO: create rb channel */
	84	list_add(&chan->list, &session->chan);
	85	mutex_unlock(&sessions_mutex);
	86	return chan;
	87
	88	exist:
e5382b6d	89	active:
4e3c1b9b MD	90	mutex_unlock(&sessions_mutex);
	91	return NULL;
	92	}
	93
	94	/*
	95	* Only used internally at session destruction.
	96	*/
	97	int _ltt_channel_destroy(struct ltt_channel *chan)
	98	{
abcca994	99	/* TODO: destroy rb channel */
4e3c1b9b MD	100	list_del(&chan->list);
	101	kfree(chan);
	102	}
	103
e5382b6d MD	104	/*
	105	* Supports event creation while tracing session is active.
	106	*/
4e3c1b9b MD	107	struct ltt_event ltt_event_create(struct ltt_channel chan, char *name,
	108	void *filter)
	109	{
	110	struct ltt_event *event;
3d084699	111	int ret;
4e3c1b9b MD	112
4e3c1b9b MD	113	mutex_lock(&sessions_mutex);
e5382b6d MD	114	if (chan->free_event_id == -1UL)
e5382b6d MD	115	goto full;
4e3c1b9b MD	116	/*
	117	* This is O(n^2) (for each event loop called at event creation).
	118	* Might require a hash if we have lots of events.
	119	*/
	120	list_for_each_entry(event, &chan->session->events, list)
	121	if (!strcmp(event->name, name))
	122	goto exist;
	123	event = kmem_cache_zalloc(events_cache, GFP_KERNEL);
	124	if (!event)
	125	goto cache_error;
	126	event->name = kmalloc(strlen(name) + 1, GFP_KERNEL);
	127	if (!event->name)
	128	goto error;
	129	strcpy(event->name, name);
	130	event->chan = chan;
	131	event->filter = filter;
e5382b6d	132	event->id = chan->free_event_id++;
4e3c1b9b	133	mutex_unlock(&sessions_mutex);
e5382b6d MD	134	/* Populate ltt_event structure before tracepoint registration. */
e5382b6d MD	135	smp_wmb();
4e3c1b9b MD	136	return event;
	137
	138	error:
	139	kmem_cache_free(event);
	140	cache_error:
	141	exist:
e5382b6d	142	full:
4e3c1b9b MD	143	mutex_unlock(&sessions_mutex);
	144	return NULL;
	145	}
	146
	147	/*
	148	* Only used internally at session destruction.
	149	*/
	150	int _ltt_event_destroy(struct ltt_event *event)
	151	{
	152	/* TODO unregister from tracepoint */
	153	kfree(event->name);
	154	kmem_cache_free(event);
	155	}
	156
	157	static int __init ltt_events_init(void)
	158	{
	159	int ret;
	160
	161	events_cache = KMEM_CACHE(ltt_event, 0);
	162	if (!events_cache)
	163	return -ENOMEM;
92e94819 MD	164
	165	/* TODO: show ABI to userspace */
	166
4e3c1b9b MD	167	return 0;
	168	}
	169
	170	static void __exit ltt_events_exit(void)
	171	{
92e94819 MD	172	struct ltt_session session, tmpsession;
	173
	174	/* TODO: hide ABI from userspace, wait for callers to release refs. */
	175
	176	list_for_each_entry_safe(session, tmpsession, &sessions, list)
	177	ltt_session_destroy(session);
4e3c1b9b MD	178	kmem_cache_destroy(events_cache);
4e3c1b9b MD	179	}
92e94819 MD	180
	181	MODULE_LICENSE("GPL and additional rights");
	182	MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
	183	MODULE_DESCRIPTION("LTTng Events");