[lttng-modules.git] / lttng-clock.c

/*
 * lttng-clock.c
 *
 * Copyright (C) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; only
 * version 2.1 of the License.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <linux/module.h>
#include <linux/kmod.h>
#include <linux/mutex.h>

#include <wrapper/trace-clock.h>
#include <lttng-events.h>
#include <lttng-tracer.h>

struct lttng_trace_clock *lttng_trace_clock;
EXPORT_SYMBOL_GPL(lttng_trace_clock);

static DEFINE_MUTEX(clock_mutex);
static struct module *lttng_trace_clock_mod;	/* plugin */
static int clock_used;				/* refcount */

int lttng_clock_register_plugin(struct lttng_trace_clock *ltc,
		struct module *mod)
{
	int ret = 0;

	mutex_lock(&clock_mutex);
	if (clock_used) {
		ret = -EBUSY;
		goto end;
	}
	if (lttng_trace_clock_mod) {
		ret = -EEXIST;
		goto end;
	}
	/* set clock */
	ACCESS_ONCE(lttng_trace_clock) = ltc;
	lttng_trace_clock_mod = mod;
end:
	mutex_unlock(&clock_mutex);
	return ret;
}
EXPORT_SYMBOL_GPL(lttng_clock_register_plugin);

void lttng_clock_unregister_plugin(struct lttng_trace_clock *ltc,
		struct module *mod)
{
	mutex_lock(&clock_mutex);
	WARN_ON_ONCE(clock_used);
	if (!lttng_trace_clock_mod) {
		goto end;
	}
	WARN_ON_ONCE(lttng_trace_clock_mod != mod);

	ACCESS_ONCE(lttng_trace_clock) = NULL;
	lttng_trace_clock_mod = NULL;
end:
	mutex_unlock(&clock_mutex);
}
EXPORT_SYMBOL_GPL(lttng_clock_unregister_plugin);

void lttng_clock_ref(void)
{
	mutex_lock(&clock_mutex);
	clock_used++;
	if (lttng_trace_clock_mod) {
		int ret;

		ret = try_module_get(lttng_trace_clock_mod);
		if (!ret) {
			printk(KERN_ERR "LTTng-clock cannot get clock plugin module\n");
			ACCESS_ONCE(lttng_trace_clock) = NULL;
			lttng_trace_clock_mod = NULL;
		}
	}
	mutex_unlock(&clock_mutex);
}
EXPORT_SYMBOL_GPL(lttng_clock_ref);

void lttng_clock_unref(void)
{
	mutex_lock(&clock_mutex);
	clock_used--;
	if (lttng_trace_clock_mod)
		module_put(lttng_trace_clock_mod);
	mutex_unlock(&clock_mutex);
}
EXPORT_SYMBOL_GPL(lttng_clock_unref);

MODULE_LICENSE("GPL and additional rights");
MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
MODULE_DESCRIPTION("LTTng Clock");
MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
	LTTNG_MODULES_EXTRAVERSION);
Commit	Line	Data
2754583e MD	1	/*
	2	* lttng-clock.c
	3	*
	4	* Copyright (C) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	5	*
	6	* This library is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU Lesser General Public
	8	* License as published by the Free Software Foundation; only
	9	* version 2.1 of the License.
	10	*
	11	* This library is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	14	* Lesser General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU Lesser General Public
	17	* License along with this library; if not, write to the Free Software
	18	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	19	*/
	20
	21	#include <linux/module.h>
	22	#include <linux/kmod.h>
	23	#include <linux/mutex.h>
	24
241ae9a8 MD	25	#include <wrapper/trace-clock.h>
	26	#include <lttng-events.h>
	27	#include <lttng-tracer.h>
2754583e MD	28
	29	struct lttng_trace_clock *lttng_trace_clock;
	30	EXPORT_SYMBOL_GPL(lttng_trace_clock);
	31
	32	static DEFINE_MUTEX(clock_mutex);
	33	static struct module lttng_trace_clock_mod; / plugin */
	34	static int clock_used; /* refcount */
	35
	36	int lttng_clock_register_plugin(struct lttng_trace_clock *ltc,
	37	struct module *mod)
	38	{
	39	int ret = 0;
	40
	41	mutex_lock(&clock_mutex);
	42	if (clock_used) {
	43	ret = -EBUSY;
	44	goto end;
	45	}
	46	if (lttng_trace_clock_mod) {
	47	ret = -EEXIST;
	48	goto end;
	49	}
	50	/* set clock */
	51	ACCESS_ONCE(lttng_trace_clock) = ltc;
	52	lttng_trace_clock_mod = mod;
	53	end:
	54	mutex_unlock(&clock_mutex);
	55	return ret;
	56	}
	57	EXPORT_SYMBOL_GPL(lttng_clock_register_plugin);
	58
	59	void lttng_clock_unregister_plugin(struct lttng_trace_clock *ltc,
	60	struct module *mod)
	61	{
	62	mutex_lock(&clock_mutex);
	63	WARN_ON_ONCE(clock_used);
	64	if (!lttng_trace_clock_mod) {
	65	goto end;
	66	}
	67	WARN_ON_ONCE(lttng_trace_clock_mod != mod);
	68
	69	ACCESS_ONCE(lttng_trace_clock) = NULL;
	70	lttng_trace_clock_mod = NULL;
	71	end:
	72	mutex_unlock(&clock_mutex);
	73	}
	74	EXPORT_SYMBOL_GPL(lttng_clock_unregister_plugin);
	75
	76	void lttng_clock_ref(void)
	77	{
	78	mutex_lock(&clock_mutex);
	79	clock_used++;
	80	if (lttng_trace_clock_mod) {
	81	int ret;
	82
	83	ret = try_module_get(lttng_trace_clock_mod);
	84	if (!ret) {
	85	printk(KERN_ERR "LTTng-clock cannot get clock plugin module\n");
	86	ACCESS_ONCE(lttng_trace_clock) = NULL;
	87	lttng_trace_clock_mod = NULL;
	88	}
	89	}
	90	mutex_unlock(&clock_mutex);
	91	}
92	EXPORT_SYMBOL_GPL(lttng_clock_ref);
93
94	void lttng_clock_unref(void)
95	{
96	mutex_lock(&clock_mutex);
97	clock_used--;
98	if (lttng_trace_clock_mod)
99	module_put(lttng_trace_clock_mod);
100	mutex_unlock(&clock_mutex);
101	}
102	EXPORT_SYMBOL_GPL(lttng_clock_unref);
103
104	MODULE_LICENSE("GPL and additional rights");
105	MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
106	MODULE_DESCRIPTION("LTTng Clock");
107	MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
108	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
109	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
110	LTTNG_MODULES_EXTRAVERSION);