path: root/kernel/trace/trace_events_trigger.c

/*
 * trace_events_trigger - trace event triggers
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (C) 2013 Tom Zanussi <tom.zanussi@linux.intel.com>
 */

#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/mutex.h>
#include <linux/slab.h>

#include "trace.h"

static LIST_HEAD(trigger_commands);
static DEFINE_MUTEX(trigger_cmd_mutex);

void trigger_data_free(struct event_trigger_data *data)
{
	if (data->cmd_ops->set_filter)
		data->cmd_ops->set_filter(NULL, data, NULL);

	synchronize_sched(); /* make sure current triggers exit before free */
	kfree(data);
}

/**
 * event_triggers_call - Call triggers associated with a trace event
 * @file: The trace_event_file associated with the event
 * @rec: The trace entry for the event, NULL for unconditional invocation
 *
 * For each trigger associated with an event, invoke the trigger
 * function registered with the associated trigger command.  If rec is
 * non-NULL, it means that the trigger requires further processing and
 * shouldn't be unconditionally invoked.  If rec is non-NULL and the
 * trigger has a filter associated with it, rec will checked against
 * the filter and if the record matches the trigger will be invoked.
 * If the trigger is a 'post_trigger', meaning it shouldn't be invoked
 * in any case until the current event is written, the trigger
 * function isn't invoked but the bit associated with the deferred
 * trigger is set in the return value.
 *
 * Returns an enum event_trigger_type value containing a set bit for
 * any trigger that should be deferred, ETT_NONE if nothing to defer.
 *
 * Called from tracepoint handlers (with rcu_read_lock_sched() held).
 *
 * Return: an enum event_trigger_type value containing a set bit for
 * any trigger that should be deferred, ETT_NONE if nothing to defer.
 */
enum event_trigger_type
event_triggers_call(struct trace_event_file *file, void *rec)
{
	struct event_trigger_data *data;
	enum event_trigger_type tt = ETT_NONE;
	struct event_filter *filter;

	if (list_empty(&file->triggers))
		return tt;

	list_for_each_entry_rcu(data, &file->triggers, list) {
		if (data->paused)
			continue;
		if (!rec) {
			data->ops->func(data, rec);
			continue;
		}
		filter = rcu_dereference_sched(data->filter);
		if (filter && !filter_match_preds(filter, rec))
			continue;
		if (event_command_post_trigger(data->cmd_ops)) {
			tt |= data->cmd_ops->trigger_type;
			continue;
		}
		data->ops->func(data, rec);
	}
	return tt;
}
EXPORT_SYMBOL_GPL(event_triggers_call);

/**
 * event_triggers_post_call - Call 'post_triggers' for a trace event
 * @file: The trace_event_file associated with the event
 * @tt: enum event_trigger_type containing a set bit for each trigger to invoke
 * @rec: The trace entry for the event
 *
 * For each trigger associated with an event, invoke the trigger
 * function registered with the associated trigger command, if the
 * corresponding bit is set in the tt enum passed into this function.
 * See @event_triggers_call for details on how those bits are set.
 *
 * Called from tracepoint handlers (with rcu_read_lock_sched() held).
 */
void
event_triggers_post_call(struct trace_event_file *file,
			 enum event_trigger_type tt,
			 void *rec)
{
	struct event_trigger_data *data;

	list_for_each_entry_rcu(data, &file->triggers, list) {
		if (data->paused)
			continue;
		if (data->cmd_ops->trigger_type & tt)
			data->ops->func(data, rec);
	}
}
EXPORT_SYMBOL_GPL(event_triggers_post_call);

#define SHOW_AVAILABLE_TRIGGERS	(void *)(1UL)

static void *trigger_next(struct seq_file *m, void *t, loff_t *pos)
{
	struct trace_event_file *event_file = event_file_data(m->private);

	if (t == SHOW_AVAILABLE_TRIGGERS)
		return NULL;

	return seq_list_next(t, &event_file->triggers, pos);
}

static void *trigger_start(struct seq_file *m, loff_t *pos)
{
	struct trace_event_file *event_file;

	/* ->stop() is called