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Commit 7862ad18 authored by Tom Zanussi's avatar Tom Zanussi Committed by Steven Rostedt
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tracing: Add 'enable_event' and 'disable_event' event trigger commands 

Add 'enable_event' and 'disable_event' event_command commands.

enable_event and disable_event event triggers are added by the user
via these commands in a similar way and using practically the same
syntax as the analagous 'enable_event' and 'disable_event' ftrace
function commands, but instead of writing to the set_ftrace_filter
file, the enable_event and disable_event triggers are written to the
per-event 'trigger' files:

    echo 'enable_event:system:event' > .../othersys/otherevent/trigger
    echo 'disable_event:system:event' > .../othersys/otherevent/trigger

The above commands will enable or disable the 'system:event' trace
events whenever the othersys:otherevent events are hit.

This also adds a 'count' version that limits the number of times the
command will be invoked:

    echo 'enable_event:system:event:N' > .../othersys/otherevent/trigger
    echo 'disable_event:system:event:N' > .../othersys/otherevent/trigger

Where N is the number of times the command will be invoked.

The above commands will will enable or disable the 'system:event'
trace events whenever the othersys:otherevent events are hit, but only
N times.

This also makes the find_event_file() helper function extern, since
it's useful to use from other places, such as the event triggers code,
so make it accessible.

Link: http://lkml.kernel.org/r/f825f3048c3f6b026ee37ae5825f9fc373451828.1382622043.git.tom.zanussi@linux.intel.com



Signed-off-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent f21ecbb3

include/linux/ftrace_event.h

+1 −0
Original line number Diff line number Diff line
@@ -348,6 +348,7 @@ enum event_trigger_type { 
	ETT_TRACE_ONOFF		= (1 << 0),

	ETT_SNAPSHOT		= (1 << 1),

	ETT_STACKTRACE		= (1 << 2),

	ETT_EVENT_ENABLE	= (1 << 3),

};



extern void destroy_preds(struct ftrace_event_file *file);

kernel/trace/trace.h

+4 −0
Original line number Diff line number Diff line
@@ -1028,6 +1028,10 @@ extern void trace_event_enable_cmd_record(bool enable); 
extern int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr);

extern int event_trace_del_tracer(struct trace_array *tr);



extern struct ftrace_event_file *find_event_file(struct trace_array *tr,

						 const char *system,

						 const char *event);



static inline void *event_file_data(struct file *filp)

{

	return ACCESS_ONCE(file_inode(filp)->i_private);

kernel/trace/trace_events.c

+1 −1
Original line number Diff line number Diff line
@@ -1868,7 +1868,7 @@ struct event_probe_data { 
	bool				enable;

};



static struct ftrace_event_file *

struct ftrace_event_file *

find_event_file(struct trace_array *tr, const char *system,  const char *event)

{

	struct ftrace_event_file *file;

kernel/trace/trace_events_trigger.c

+359 −0
Original line number Diff line number Diff line
@@ -864,6 +864,364 @@ static __init void unregister_trigger_traceon_traceoff_cmds(void) 
	unregister_event_command(&trigger_traceoff_cmd);

}



/* Avoid typos */

#define ENABLE_EVENT_STR	"enable_event"

#define DISABLE_EVENT_STR	"disable_event"



struct enable_trigger_data {

	struct ftrace_event_file	*file;

	bool				enable;

};



static void

event_enable_trigger(struct event_trigger_data *data)

{

	struct enable_trigger_data *enable_data = data->private_data;



	if (enable_data->enable)

		clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);

	else

		set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);

}



static void

event_enable_count_trigger(struct event_trigger_data *data)

{

	struct enable_trigger_data *enable_data = data->private_data;



	if (!data->count)

		return;



	/* Skip if the event is in a state we want to switch to */

	if (enable_data->enable == !(enable_data->file->flags & FTRACE_EVENT_FL_SOFT_DISABLED))

		return;



	if (data->count != -1)

		(data->count)--;



	event_enable_trigger(data);

}



static int

event_enable_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,

			   struct event_trigger_data *data)

{

	struct enable_trigger_data *enable_data = data->private_data;



	seq_printf(m, "%s:%s:%s",

		   enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,

		   enable_data->file->event_call->class->system,

		   enable_data->file->event_call->name);



	if (data->count == -1)

		seq_puts(m, ":unlimited");

	else

		seq_printf(m, ":count=%ld", data->count);



	if (data->filter_str)

		seq_printf(m, " if %s\n", data->filter_str);

	else

		seq_puts(m, "\n");



	return 0;

}



static void

event_enable_trigger_free(struct event_trigger_ops *ops,

			  struct event_trigger_data *data)

{

	struct enable_trigger_data *enable_data = data->private_data;



	if (WARN_ON_ONCE(data->ref <= 0))

		return;



	data->ref--;

	if (!data->ref) {

		/* Remove the SOFT_MODE flag */

		trace_event_enable_disable(enable_data->file, 0, 1);

		module_put(enable_data->file->event_call->mod);

		trigger_data_free(data);

		kfree(enable_data);

	}

}



static struct event_trigger_ops event_enable_trigger_ops = {

	.func			= event_enable_trigger,

	.print			= event_enable_trigger_print,

	.init			= event_trigger_init,

	.free			= event_enable_trigger_free,

};



static struct event_trigger_ops event_enable_count_trigger_ops = {

	.func			= event_enable_count_trigger,

	.print			= event_enable_trigger_print,

	.init			= event_trigger_init,

	.free			= event_enable_trigger_free,

};



static struct event_trigger_ops event_disable_trigger_ops = {

	.func			= event_enable_trigger,

	.print			= event_enable_trigger_print,

	.init			= event_trigger_init,

	.free			= event_enable_trigger_free,

};



static struct event_trigger_ops event_disable_count_trigger_ops = {

	.func			= event_enable_count_trigger,

	.print			= event_enable_trigger_print,

	.init			= event_trigger_init,

	.free			= event_enable_trigger_free,

};



static int

event_enable_trigger_func(struct event_command *cmd_ops,

			  struct ftrace_event_file *file,

			  char *glob, char *cmd, char *param)

{

	struct ftrace_event_file *event_enable_file;

	struct enable_trigger_data *enable_data;

	struct event_trigger_data *trigger_data;

	struct event_trigger_ops *trigger_ops;

	struct trace_array *tr = file->tr;

	const char *system;

	const char *event;

	char *trigger;

	char *number;

	bool enable;

	int ret;



	if (!param)

		return -EINVAL;



	/* separate the trigger from the filter (s:e:n [if filter]) */

	trigger = strsep(&param, " \t");

	if (!trigger)

		return -EINVAL;



	system = strsep(&trigger, ":");

	if (!trigger)

		return -EINVAL;



	event = strsep(&trigger, ":");



	ret = -EINVAL;

	event_enable_file = find_event_file(tr, system, event);

	if (!event_enable_file)

		goto out;



	enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;



	trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);



	ret = -ENOMEM;

	trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);

	if (!trigger_data)

		goto out;



	enable_data = kzalloc(sizeof(*enable_data), GFP_KERNEL);

	if (!enable_data) {

		kfree(trigger_data);

		goto out;

	}



	trigger_data->count = -1;

	trigger_data->ops = trigger_ops;

	trigger_data->cmd_ops = cmd_ops;

	INIT_LIST_HEAD(&trigger_data->list);

	RCU_INIT_POINTER(trigger_data->filter, NULL);



	enable_data->enable = enable;

	enable_data->file = event_enable_file;

	trigger_data->private_data = enable_data;



	if (glob[0] == '!') {

		cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);

		kfree(trigger_data);

		kfree(enable_data);

		ret = 0;

		goto out;

	}



	if (trigger) {

		number = strsep(&trigger, ":");



		ret = -EINVAL;

		if (!strlen(number))

			goto out_free;



		/*

		 * We use the callback data field (which is a pointer)

		 * as our counter.

		 */

		ret = kstrtoul(number, 0, &trigger_data->count);

		if (ret)

			goto out_free;

	}



	if (!param) /* if param is non-empty, it's supposed to be a filter */

		goto out_reg;



	if (!cmd_ops->set_filter)

		goto out_reg;



	ret = cmd_ops->set_filter(param, trigger_data, file);

	if (ret < 0)

		goto out_free;



 out_reg:

	/* Don't let event modules unload while probe registered */

	ret = try_module_get(event_enable_file->event_call->mod);

	if (!ret) {

		ret = -EBUSY;

		goto out_free;

	}



	ret = trace_event_enable_disable(event_enable_file, 1, 1);

	if (ret < 0)

		goto out_put;

	ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);

	/*

	 * The above returns on success the # of functions enabled,

	 * but if it didn't find any functions it returns zero.

	 * Consider no functions a failure too.

	 */

	if (!ret) {

		ret = -ENOENT;

		goto out_disable;

	} else if (ret < 0)

		goto out_disable;

	/* Just return zero, not the number of enabled functions */

	ret = 0;

 out:

	return ret;



 out_disable:

	trace_event_enable_disable(event_enable_file, 0, 1);

 out_put:

	module_put(event_enable_file->event_call->mod);

 out_free:

	kfree(trigger_data);

	kfree(enable_data);

	goto out;

}



static int event_enable_register_trigger(char *glob,

					 struct event_trigger_ops *ops,

					 struct event_trigger_data *data,

					 struct ftrace_event_file *file)

{

	struct enable_trigger_data *enable_data = data->private_data;

	struct enable_trigger_data *test_enable_data;

	struct event_trigger_data *test;

	int ret = 0;



	list_for_each_entry_rcu(test, &file->triggers, list) {

		test_enable_data = test->private_data;

		if (test_enable_data &&

		    (test_enable_data->file == enable_data->file)) {

			ret = -EEXIST;

			goto out;

		}

	}



	if (data->ops->init) {

		ret = data->ops->init(data->ops, data);

		if (ret < 0)

			goto out;

	}



	list_add_rcu(&data->list, &file->triggers);

	ret++;



	if (trace_event_trigger_enable_disable(file, 1) < 0) {

		list_del_rcu(&data->list);

		ret--;

	}

out:

	return ret;

}



static void event_enable_unregister_trigger(char *glob,

					    struct event_trigger_ops *ops,

					    struct event_trigger_data *test,

					    struct ftrace_event_file *file)

{

	struct enable_trigger_data *test_enable_data = test->private_data;

	struct enable_trigger_data *enable_data;

	struct event_trigger_data *data;

	bool unregistered = false;



	list_for_each_entry_rcu(data, &file->triggers, list) {

		enable_data = data->private_data;

		if (enable_data &&

		    (enable_data->file == test_enable_data->file)) {

			unregistered = true;

			list_del_rcu(&data->list);

			trace_event_trigger_enable_disable(file, 0);

			break;

		}

	}



	if (unregistered && data->ops->free)

		data->ops->free(data->ops, data);

}



static struct event_trigger_ops *

event_enable_get_trigger_ops(char *cmd, char *param)

{

	struct event_trigger_ops *ops;

	bool enable;



	enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;



	if (enable)

		ops = param ? &event_enable_count_trigger_ops :

			&event_enable_trigger_ops;

	else

		ops = param ? &event_disable_count_trigger_ops :

			&event_disable_trigger_ops;



	return ops;

}



static struct event_command trigger_enable_cmd = {

	.name			= ENABLE_EVENT_STR,

	.trigger_type		= ETT_EVENT_ENABLE,

	.func			= event_enable_trigger_func,

	.reg			= event_enable_register_trigger,

	.unreg			= event_enable_unregister_trigger,

	.get_trigger_ops	= event_enable_get_trigger_ops,

};



static struct event_command trigger_disable_cmd = {

	.name			= DISABLE_EVENT_STR,

	.trigger_type		= ETT_EVENT_ENABLE,

	.func			= event_enable_trigger_func,

	.reg			= event_enable_register_trigger,

	.unreg			= event_enable_unregister_trigger,

	.get_trigger_ops	= event_enable_get_trigger_ops,

};



static __init void unregister_trigger_enable_disable_cmds(void)

{

	unregister_event_command(&trigger_enable_cmd);

	unregister_event_command(&trigger_disable_cmd);

}



static __init int register_trigger_enable_disable_cmds(void)

{

	int ret;



	ret = register_event_command(&trigger_enable_cmd);

	if (WARN_ON(ret < 0))

		return ret;

	ret = register_event_command(&trigger_disable_cmd);

	if (WARN_ON(ret < 0))

		unregister_trigger_enable_disable_cmds();



	return ret;

}



static __init int register_trigger_traceon_traceoff_cmds(void)

{

	int ret;
@@ -883,6 +1241,7 @@ __init int register_trigger_cmds(void) 
	register_trigger_traceon_traceoff_cmds();

	register_trigger_snapshot_cmd();

	register_trigger_stacktrace_cmd();

	register_trigger_enable_disable_cmds();



	return 0;

}