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Commit dff81f55 authored by Tom Zanussi's avatar Tom Zanussi Committed by Steven Rostedt (VMware)
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tracing: Add hist trigger onchange() handler 

Add support for a hist:onchange($var) handler, similar to the onmax()
handler but triggering whenever there's any change in $var, not just a
max.

Link: http://lkml.kernel.org/r/dfbc7e4ada242603e9ec3f049b5ad076a07dfd03.1550100284.git.tom.zanussi@linux.intel.com



Signed-off-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent fd451a3d

kernel/trace/trace.c

+2 −1
Original line number Diff line number Diff line
@@ -4915,7 +4915,8 @@ static const char readme_msg[] = 
	"\t        <handler>.<action>\n\n"

	"\t    The available handlers are:\n\n"

	"\t        onmatch(matching.event)  - invoke on addition or update\n"

	"\t        onmax(var)               - invoke if var exceeds current max\n\n"

	"\t        onmax(var)               - invoke if var exceeds current max\n"

	"\t        onchange(var)            - invoke action if var changes\n\n"

	"\t    The available actions are:\n\n"

	"\t        <synthetic_event>(param list)        - generate synthetic event\n"

	"\t        save(field,...)                      - save current event fields\n"

kernel/trace/trace_events_hist.c

+50 −8
Original line number Diff line number Diff line
@@ -391,6 +391,7 @@ typedef bool (*check_track_val_fn_t) (u64 track_val, u64 var_val); 
enum handler_id {

	HANDLER_ONMATCH = 1,

	HANDLER_ONMAX,

	HANDLER_ONCHANGE,

};



enum action_id {
@@ -1989,7 +1990,8 @@ static int parse_action(char *str, struct hist_trigger_attrs *attrs) 
		return ret;



	if ((str_has_prefix(str, "onmatch(")) ||

	    (str_has_prefix(str, "onmax("))) {

	    (str_has_prefix(str, "onmax(")) ||

	    (str_has_prefix(str, "onchange("))) {

		attrs->action_str[attrs->n_actions] = kstrdup(str, GFP_KERNEL);

		if (!attrs->action_str[attrs->n_actions]) {

			ret = -ENOMEM;
@@ -3481,6 +3483,14 @@ static bool check_track_val_max(u64 track_val, u64 var_val) 
	return true;

}



static bool check_track_val_changed(u64 track_val, u64 var_val)

{

	if (var_val == track_val)

		return false;



	return true;

}



static u64 get_track_val(struct hist_trigger_data *hist_data,

			 struct tracing_map_elt *elt,

			 struct action_data *data)
@@ -3640,6 +3650,8 @@ static void track_data_print(struct seq_file *m, 


	if (data->handler == HANDLER_ONMAX)

		seq_printf(m, "\n\tmax: %10llu", track_val);

	else if (data->handler == HANDLER_ONCHANGE)

		seq_printf(m, "\n\tchanged: %10llu", track_val);



	if (data->action == ACTION_SNAPSHOT)

		return;
@@ -3727,14 +3739,14 @@ static int track_data_create(struct hist_trigger_data *hist_data, 


	track_data_var_str = data->track_data.var_str;

	if (track_data_var_str[0] != '$') {

		hist_err("For onmax(x), x must be a variable: ", track_data_var_str);

		hist_err("For onmax(x) or onchange(x), x must be a variable: ", track_data_var_str);

		return -EINVAL;

	}

	track_data_var_str++;



	var_field = find_target_event_var(hist_data, NULL, NULL, track_data_var_str);

	if (!var_field) {

		hist_err("Couldn't find onmax variable: ", track_data_var_str);

		hist_err("Couldn't find onmax or onchange variable: ", track_data_var_str);

		return -EINVAL;

	}
@@ -3751,6 +3763,14 @@ static int track_data_create(struct hist_trigger_data *hist_data, 
		ret = PTR_ERR(track_var);

		goto out;

	}



	if (data->handler == HANDLER_ONCHANGE)

		track_var = create_var(hist_data, file, "__change", sizeof(u64), "u64");

	if (IS_ERR(track_var)) {

		hist_err("Couldn't create onchange variable: ", "__change");

		ret = PTR_ERR(track_var);

		goto out;

	}

	data->track_data.track_var = track_var;



	ret = action_create(hist_data, data);
@@ -3830,6 +3850,8 @@ static int action_parse(char *str, struct action_data *data, 


		if (handler == HANDLER_ONMAX)

			data->track_data.check_val = check_track_val_max;

		else if (handler == HANDLER_ONCHANGE)

			data->track_data.check_val = check_track_val_changed;

		else {

			hist_err("action parsing: Handler doesn't support action: ", action_name);

			ret = -EINVAL;
@@ -3850,6 +3872,8 @@ static int action_parse(char *str, struct action_data *data, 


		if (handler == HANDLER_ONMAX)

			data->track_data.check_val = check_track_val_max;

		else if (handler == HANDLER_ONCHANGE)

			data->track_data.check_val = check_track_val_changed;

		else {

			hist_err("action parsing: Handler doesn't support action: ", action_name);

			ret = -EINVAL;
@@ -3870,6 +3894,8 @@ static int action_parse(char *str, struct action_data *data, 


		if (handler == HANDLER_ONMAX)

			data->track_data.check_val = check_track_val_max;

		else if (handler == HANDLER_ONCHANGE)

			data->track_data.check_val = check_track_val_changed;



		if (handler != HANDLER_ONMATCH) {

			data->track_data.save_data = action_trace;
@@ -4700,7 +4726,8 @@ static void destroy_actions(struct hist_trigger_data *hist_data) 


		if (data->handler == HANDLER_ONMATCH)

			onmatch_destroy(data);

		else if (data->handler == HANDLER_ONMAX)

		else if (data->handler == HANDLER_ONMAX ||

			 data->handler == HANDLER_ONCHANGE)

			track_data_destroy(hist_data, data);

		else

			kfree(data);
@@ -4736,6 +4763,15 @@ static int parse_actions(struct hist_trigger_data *hist_data) 
				ret = PTR_ERR(data);

				break;

			}

		} else if ((len = str_has_prefix(str, "onchange("))) {

			char *action_str = str + len;



			data = track_data_parse(hist_data, action_str,

						HANDLER_ONCHANGE);

			if (IS_ERR(data)) {

				ret = PTR_ERR(data);

				break;

			}

		} else {

			ret = -EINVAL;

			break;
@@ -4760,7 +4796,8 @@ static int create_actions(struct hist_trigger_data *hist_data) 
			ret = onmatch_create(hist_data, data);

			if (ret)

				break;

		} else if (data->handler == HANDLER_ONMAX) {

		} else if (data->handler == HANDLER_ONMAX ||

			   data->handler == HANDLER_ONCHANGE) {

			ret = track_data_create(hist_data, data);

			if (ret)

				break;
@@ -4785,7 +4822,8 @@ static void print_actions(struct seq_file *m, 
		if (data->action == ACTION_SNAPSHOT)

			continue;



		if (data->handler == HANDLER_ONMAX)

		if (data->handler == HANDLER_ONMAX ||

		    data->handler == HANDLER_ONCHANGE)

			track_data_print(m, hist_data, elt, data);

	}

}
@@ -4817,6 +4855,8 @@ static void print_track_data_spec(struct seq_file *m, 
{

	if (data->handler == HANDLER_ONMAX)

		seq_puts(m, ":onmax(");

	else if (data->handler == HANDLER_ONCHANGE)

		seq_puts(m, ":onchange(");

	seq_printf(m, "%s", data->track_data.var_str);

	seq_printf(m, ").%s(", data->action_name);
@@ -4874,7 +4914,8 @@ static bool actions_match(struct hist_trigger_data *hist_data, 
			if (strcmp(data->match_data.event,

				   data_test->match_data.event) != 0)

				return false;

		} else if (data->handler == HANDLER_ONMAX) {

		} else if (data->handler == HANDLER_ONMAX ||

			   data->handler == HANDLER_ONCHANGE) {

			if (strcmp(data->track_data.var_str,

				   data_test->track_data.var_str) != 0)

				return false;
@@ -4895,7 +4936,8 @@ static void print_actions_spec(struct seq_file *m, 


		if (data->handler == HANDLER_ONMATCH)

			print_onmatch_spec(m, hist_data, data);

		else if (data->handler == HANDLER_ONMAX)

		else if (data->handler == HANDLER_ONMAX ||

			 data->handler == HANDLER_ONCHANGE)

			print_track_data_spec(m, hist_data, data);

	}

}