[mirror_ubuntu-hirsute-kernel.git] / kernel / trace / trace_event_profile.c

/*
 * trace event based perf counter profiling
 *
 * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
 *
 */

#include <linux/module.h>
#include "trace.h"

/*
 * We can't use a size but a type in alloc_percpu()
 * So let's create a dummy type that matches the desired size
 */
typedef struct {char buf[FTRACE_MAX_PROFILE_SIZE];} profile_buf_t;

char		*trace_profile_buf;
EXPORT_SYMBOL_GPL(trace_profile_buf);

char		*trace_profile_buf_nmi;
EXPORT_SYMBOL_GPL(trace_profile_buf_nmi);

/* Count the events in use (per event id, not per instance) */
static int	total_profile_count;

static int ftrace_profile_enable_event(struct ftrace_event_call *event)
{
	char *buf;
	int ret = -ENOMEM;

	if (atomic_inc_return(&event->profile_count))
		return 0;

	if (!total_profile_count++) {
		buf = (char *)alloc_percpu(profile_buf_t);
		if (!buf)
			goto fail_buf;

		rcu_assign_pointer(trace_profile_buf, buf);

		buf = (char *)alloc_percpu(profile_buf_t);
		if (!buf)
			goto fail_buf_nmi;

		rcu_assign_pointer(trace_profile_buf_nmi, buf);
	}

	ret = event->profile_enable();
	if (!ret)
		return 0;

	kfree(trace_profile_buf_nmi);
fail_buf_nmi:
	kfree(trace_profile_buf);
fail_buf:
	total_profile_count--;
	atomic_dec(&event->profile_count);

	return ret;
}

int ftrace_profile_enable(int event_id)
{
	struct ftrace_event_call *event;
	int ret = -EINVAL;

	mutex_lock(&event_mutex);
	list_for_each_entry(event, &ftrace_events, list) {
		if (event->id == event_id && event->profile_enable &&
		    try_module_get(event->mod)) {
			ret = ftrace_profile_enable_event(event);
			break;
		}
	}
	mutex_unlock(&event_mutex);

	return ret;
}

static void ftrace_profile_disable_event(struct ftrace_event_call *event)
{
	char *buf, *nmi_buf;

	if (!atomic_add_negative(-1, &event->profile_count))
		return;

	event->profile_disable();

	if (!--total_profile_count) {
		buf = trace_profile_buf;
		rcu_assign_pointer(trace_profile_buf, NULL);

		nmi_buf = trace_profile_buf_nmi;
		rcu_assign_pointer(trace_profile_buf_nmi, NULL);

		/*
		 * Ensure every events in profiling have finished before
		 * releasing the buffers
		 */
		synchronize_sched();

		free_percpu(buf);
		free_percpu(nmi_buf);
	}
}

void ftrace_profile_disable(int event_id)
{
	struct ftrace_event_call *event;

	mutex_lock(&event_mutex);
	list_for_each_entry(event, &ftrace_events, list) {
		if (event->id == event_id) {
			ftrace_profile_disable_event(event);
			module_put(event->mod);
			break;
		}
	}
	mutex_unlock(&event_mutex);
}
Commit	Line	Data
ac199db0 PZ	1	/*
	2	* trace event based perf counter profiling
	3	*
	4	* Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
	5	*
	6	*/
	7
558e6547	8	#include <linux/module.h>
ac199db0 PZ	9	#include "trace.h"
ac199db0 PZ	10
20ab4425 FW	11	/*
	12	* We can't use a size but a type in alloc_percpu()
	13	* So let's create a dummy type that matches the desired size
	14	*/
	15	typedef struct {char buf[FTRACE_MAX_PROFILE_SIZE];} profile_buf_t;
	16
	17	char *trace_profile_buf;
05bafda8 PZ	18	EXPORT_SYMBOL_GPL(trace_profile_buf);
	19
	20	char *trace_profile_buf_nmi;
	21	EXPORT_SYMBOL_GPL(trace_profile_buf_nmi);
20ab4425 FW	22
	23	/* Count the events in use (per event id, not per instance) */
	24	static int total_profile_count;
	25
e5e25cf4 FW	26	static int ftrace_profile_enable_event(struct ftrace_event_call *event)
e5e25cf4 FW	27	{
20ab4425 FW	28	char *buf;
	29	int ret = -ENOMEM;
	30
e5e25cf4 FW	31	if (atomic_inc_return(&event->profile_count))
	32	return 0;
	33
20ab4425 FW	34	if (!total_profile_count++) {
	35	buf = (char *)alloc_percpu(profile_buf_t);
	36	if (!buf)
	37	goto fail_buf;
	38
	39	rcu_assign_pointer(trace_profile_buf, buf);
	40
	41	buf = (char *)alloc_percpu(profile_buf_t);
	42	if (!buf)
	43	goto fail_buf_nmi;
	44
	45	rcu_assign_pointer(trace_profile_buf_nmi, buf);
	46	}
	47
	48	ret = event->profile_enable();
	49	if (!ret)
	50	return 0;
	51
	52	kfree(trace_profile_buf_nmi);
	53	fail_buf_nmi:
	54	kfree(trace_profile_buf);
	55	fail_buf:
	56	total_profile_count--;
	57	atomic_dec(&event->profile_count);
	58
	59	return ret;
e5e25cf4 FW	60	}
e5e25cf4 FW	61
ac199db0 PZ	62	int ftrace_profile_enable(int event_id)
	63	{
	64	struct ftrace_event_call *event;
20c8928a	65	int ret = -EINVAL;
ac199db0	66
20c8928a	67	mutex_lock(&event_mutex);
a59fd602	68	list_for_each_entry(event, &ftrace_events, list) {
558e6547 LZ	69	if (event->id == event_id && event->profile_enable &&
558e6547 LZ	70	try_module_get(event->mod)) {
e5e25cf4	71	ret = ftrace_profile_enable_event(event);
20c8928a LZ	72	break;
20c8928a LZ	73	}
ac199db0	74	}
20c8928a	75	mutex_unlock(&event_mutex);
ac199db0	76
20c8928a	77	return ret;
ac199db0 PZ	78	}
ac199db0 PZ	79
e5e25cf4 FW	80	static void ftrace_profile_disable_event(struct ftrace_event_call *event)
e5e25cf4 FW	81	{
20ab4425 FW	82	char buf, nmi_buf;
20ab4425 FW	83
e5e25cf4 FW	84	if (!atomic_add_negative(-1, &event->profile_count))
	85	return;
	86
	87	event->profile_disable();
20ab4425 FW	88
	89	if (!--total_profile_count) {
	90	buf = trace_profile_buf;
	91	rcu_assign_pointer(trace_profile_buf, NULL);
	92
	93	nmi_buf = trace_profile_buf_nmi;
	94	rcu_assign_pointer(trace_profile_buf_nmi, NULL);
	95
	96	/*
	97	* Ensure every events in profiling have finished before
	98	* releasing the buffers
	99	*/
	100	synchronize_sched();
	101
	102	free_percpu(buf);
	103	free_percpu(nmi_buf);
	104	}
e5e25cf4 FW	105	}
e5e25cf4 FW	106
ac199db0 PZ	107	void ftrace_profile_disable(int event_id)
	108	{
	109	struct ftrace_event_call *event;
	110
20c8928a	111	mutex_lock(&event_mutex);
a59fd602	112	list_for_each_entry(event, &ftrace_events, list) {
20c8928a	113	if (event->id == event_id) {
e5e25cf4	114	ftrace_profile_disable_event(event);
558e6547	115	module_put(event->mod);
20c8928a LZ	116	break;
20c8928a LZ	117	}
ac199db0	118	}
20c8928a	119	mutex_unlock(&event_mutex);
ac199db0	120	}