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Commit f21ecbb3 authored by Tom Zanussi's avatar Tom Zanussi Committed by Steven Rostedt
Browse files

tracing: Add 'stacktrace' event trigger command 

Add 'stacktrace' event_command.  stacktrace event triggers are added
by the user via this command in a similar way and using practically
the same syntax as the analogous 'stacktrace' ftrace function command,
but instead of writing to the set_ftrace_filter file, the stacktrace
event trigger is written to the per-event 'trigger' files:

    echo 'stacktrace' > .../tracing/events/somesys/someevent/trigger

The above command will turn on stacktraces for someevent i.e. whenever
someevent is hit, a stacktrace will be logged.

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

    echo 'stacktrace:N' > .../tracing/events/somesys/someevent/trigger

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

The above command will log N stacktraces for someevent i.e. whenever
someevent is hit N times, a stacktrace will be logged.

Link: http://lkml.kernel.org/r/0c30c008a0828c660aa0e1bbd3255cf179ed5c30.1382622043.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 93e31ffb

include/linux/ftrace_event.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -347,6 +347,7 @@ enum event_trigger_type { 
	ETT_NONE		= (0),

	ETT_NONE		= (0),

	ETT_TRACE_ONOFF		= (1 << 0),

	ETT_TRACE_ONOFF		= (1 << 0),

	ETT_SNAPSHOT		= (1 << 1),

	ETT_SNAPSHOT		= (1 << 1),

	ETT_STACKTRACE		= (1 << 2),

};

};





extern void destroy_preds(struct ftrace_event_file *file);

extern void destroy_preds(struct ftrace_event_file *file);

kernel/trace/trace_events_trigger.c

+79 −0
Original line number Original line Diff line number Diff line
@@ -780,6 +780,84 @@ static __init int register_trigger_snapshot_cmd(void) 
static __init int register_trigger_snapshot_cmd(void) { return 0; }

static __init int register_trigger_snapshot_cmd(void) { return 0; }

#endif /* CONFIG_TRACER_SNAPSHOT */

#endif /* CONFIG_TRACER_SNAPSHOT */





#ifdef CONFIG_STACKTRACE

/*

 * Skip 3:

 *   stacktrace_trigger()

 *   event_triggers_post_call()

 *   ftrace_raw_event_xxx()

 */

#define STACK_SKIP 3



static void

stacktrace_trigger(struct event_trigger_data *data)

{

	trace_dump_stack(STACK_SKIP);

}



static void

stacktrace_count_trigger(struct event_trigger_data *data)

{

	if (!data->count)

		return;



	if (data->count != -1)

		(data->count)--;



	stacktrace_trigger(data);

}



static int

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

			 struct event_trigger_data *data)

{

	return event_trigger_print("stacktrace", m, (void *)data->count,

				   data->filter_str);

}



static struct event_trigger_ops stacktrace_trigger_ops = {

	.func			= stacktrace_trigger,

	.print			= stacktrace_trigger_print,

	.init			= event_trigger_init,

	.free			= event_trigger_free,

};



static struct event_trigger_ops stacktrace_count_trigger_ops = {

	.func			= stacktrace_count_trigger,

	.print			= stacktrace_trigger_print,

	.init			= event_trigger_init,

	.free			= event_trigger_free,

};



static struct event_trigger_ops *

stacktrace_get_trigger_ops(char *cmd, char *param)

{

	return param ? &stacktrace_count_trigger_ops : &stacktrace_trigger_ops;

}



static struct event_command trigger_stacktrace_cmd = {

	.name			= "stacktrace",

	.trigger_type		= ETT_STACKTRACE,

	.post_trigger		= true,

	.func			= event_trigger_callback,

	.reg			= register_trigger,

	.unreg			= unregister_trigger,

	.get_trigger_ops	= stacktrace_get_trigger_ops,

};



static __init int register_trigger_stacktrace_cmd(void)

{

	int ret;



	ret = register_event_command(&trigger_stacktrace_cmd);

	WARN_ON(ret < 0);



	return ret;

}

#else

static __init int register_trigger_stacktrace_cmd(void) { return 0; }

#endif /* CONFIG_STACKTRACE */



static __init void unregister_trigger_traceon_traceoff_cmds(void)

static __init void unregister_trigger_traceon_traceoff_cmds(void)

{

{

	unregister_event_command(&trigger_traceon_cmd);

	unregister_event_command(&trigger_traceon_cmd);
@@ -804,6 +882,7 @@ __init int register_trigger_cmds(void) 
{

{

	register_trigger_traceon_traceoff_cmds();

	register_trigger_traceon_traceoff_cmds();

	register_trigger_snapshot_cmd();

	register_trigger_snapshot_cmd();

	register_trigger_stacktrace_cmd();





	return 0;

	return 0;

}
 
}