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Commit e86ae9ba authored Mar 03, 2016 by Tom Zanussi Committed by Steven Rostedt Apr 19, 2016

tracing: Add hist trigger support for clearing a trace

Allow users to append 'clear' to an existing trigger in order to have
the hash table cleared.

This expands the hist trigger syntax from this:
    # echo hist:keys=xxx:vals=yyy:sort=zzz.descending:pause/cont \
           [ if filter] >> event/trigger

to this:

    # echo hist:keys=xxx:vals=yyy:sort=zzz.descending:pause/cont/clear \
          [ if filter] >> event/trigger

Link: http://lkml.kernel.org/r/ae15dd0d9b2f7af07a37c1ff682063e2dbcdf160.1457029949.git.tom.zanussi@linux.intel.com



Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

parent 83e99914

kernel/trace/trace.c

+4 −1

Original line number	Original line	Diff line number	Diff line
	@@ -3837,7 +3837,7 @@ static const char readme_msg[] =
	"\t [:values=<field1[,field2,...]>]\n"		"\t [:values=<field1[,field2,...]>]\n"
	"\t [:sort=<field1[,field2,...]>]\n"		"\t [:sort=<field1[,field2,...]>]\n"
	"\t [:size=#entries]\n"		"\t [:size=#entries]\n"
	"\t [:pause][:continue]\n"		"\t [:pause][:continue][:clear]\n"
	"\t [if <filter>]\n\n"		"\t [if <filter>]\n\n"
	"\t When a matching event is hit, an entry is added to a hash\n"		"\t When a matching event is hit, an entry is added to a hash\n"
	"\t table using the key(s) and value(s) named, and the value of a\n"		"\t table using the key(s) and value(s) named, and the value of a\n"
	@@ -3857,6 +3857,9 @@ static const char readme_msg[] =
	"\t trigger or to start a hist trigger but not log any events\n"		"\t trigger or to start a hist trigger but not log any events\n"
	"\t until told to do so. 'continue' can be used to start or\n"		"\t until told to do so. 'continue' can be used to start or\n"
	"\t restart a paused hist trigger.\n\n"		"\t restart a paused hist trigger.\n\n"
			"\t The 'clear' parameter will clear the contents of a running\n"
			"\t hist trigger and leave its current paused/active state\n"
			"\t unchanged.\n\n"
	#endif		#endif
	;		;

kernel/trace/trace_events_hist.c

+22 −2

Original line number	Original line	Diff line number	Diff line
	@@ -88,6 +88,7 @@ struct hist_trigger_attrs {
	char *sort_key_str;		char *sort_key_str;
	bool pause;		bool pause;
	bool cont;		bool cont;
			bool clear;
	unsigned int map_bits;		unsigned int map_bits;
	};		};

	@@ -200,6 +201,8 @@ static struct hist_trigger_attrs parse_hist_trigger_attrs(char trigger_str)
	else if ((strcmp(str, "cont") == 0) \|\|		else if ((strcmp(str, "cont") == 0) \|\|
	(strcmp(str, "continue") == 0))		(strcmp(str, "continue") == 0))
	attrs->cont = true;		attrs->cont = true;
			else if (strcmp(str, "clear") == 0)
			attrs->clear = true;
	else if (strncmp(str, "size=", strlen("size=")) == 0) {		else if (strncmp(str, "size=", strlen("size=")) == 0) {
	int map_bits = parse_map_size(str);		int map_bits = parse_map_size(str);

	@@ -916,6 +919,21 @@ static struct event_trigger_ops event_hist_get_trigger_ops(char cmd,
	return &event_hist_trigger_ops;		return &event_hist_trigger_ops;
	}		}

			static void hist_clear(struct event_trigger_data *data)
			{
			struct hist_trigger_data *hist_data = data->private_data;
			bool paused;

			paused = data->paused;
			data->paused = true;

			synchronize_sched();

			tracing_map_clear(hist_data->map);

			data->paused = paused;
			}

	static int hist_register_trigger(char glob, struct event_trigger_ops ops,		static int hist_register_trigger(char glob, struct event_trigger_ops ops,
	struct event_trigger_data *data,		struct event_trigger_data *data,
	struct trace_event_file *file)		struct trace_event_file *file)
	@@ -930,13 +948,15 @@ static int hist_register_trigger(char glob, struct event_trigger_ops ops,
	test->paused = true;		test->paused = true;
	else if (hist_data->attrs->cont)		else if (hist_data->attrs->cont)
	test->paused = false;		test->paused = false;
			else if (hist_data->attrs->clear)
			hist_clear(test);
	else		else
	ret = -EEXIST;		ret = -EEXIST;
	goto out;		goto out;
	}		}
	}		}

	if (hist_data->attrs->cont) {		if (hist_data->attrs->cont \|\| hist_data->attrs->clear) {
	ret = -ENOENT;		ret = -ENOENT;
	goto out;		goto out;
	}		}
	@@ -1035,7 +1055,7 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
	* triggers registered a failure too.		* triggers registered a failure too.
	*/		*/
	if (!ret) {		if (!ret) {
	if (!(attrs->pause \|\| attrs->cont))		if (!(attrs->pause \|\| attrs->cont \|\| attrs->clear))
	ret = -ENOENT;		ret = -ENOENT;
	goto out_free;		goto out_free;
	} else if (ret < 0)		} else if (ret < 0)