tracing: Add support for multiple hist triggers per event

Allow users to define any number of hist triggers per trace event.
Any number of hist triggers may be added for a given event, which may
differ by key, value, or filter.

Reading the event's 'hist' file will display the output of all the
hist triggers defined on an event concatenated in the order they were
defined.

Link: http://lkml.kernel.org/r/48a0c8dd34c344571de880fb35e211c6d9a28961.1457029949.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>

2 files changed, 145 insertions, 35 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8430145bea12..e89b2ed76d2d 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3856,9 +3856,11 @@ static const char readme_msg[] =
 	"\t    sort field.  The 'size' parameter can be used to specify more\n"
 	"\t    or fewer than the default 2048 entries for the hashtable size.\n\n"
 	"\t    Reading the 'hist' file for the event will dump the hash\n"
-	"\t    table in its entirety to stdout.  The default format used to\n"
-	"\t    display a given field can be modified by appending any of the\n"
-	"\t    following modifiers to the field name, as applicable:\n\n"
+	"\t    table in its entirety to stdout.  If there are multiple hist\n"
+	"\t    triggers attached to an event, there will be a table for each\n"
+	"\t    trigger in the output.  The default format used to display a\n"
+	"\t    given field can be modified by appending any of the following\n"
+	"\t    modifiers to the field name, as applicable:\n\n"
 	"\t            .hex        display a number as a hex value\n"
 	"\t            .sym        display an address as a symbol\n"
 	"\t            .sym-offset display an address as a symbol and offset\n"
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 5d4f02792440..4b02f8ab4dd3 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1032,33 +1032,18 @@ static int print_entries(struct seq_file *m,
 	return n_entries;
 }
 
-static int hist_show(struct seq_file *m, void *v)
+static void hist_trigger_show(struct seq_file *m,
+			      struct event_trigger_data *data, int n)
 {
-	struct event_trigger_data *test, *data = NULL;
-	struct trace_event_file *event_file;
 	struct hist_trigger_data *hist_data;
 	int n_entries, ret = 0;
 
-	mutex_lock(&event_mutex);
-
-	event_file = event_file_data(m->private);
-	if (unlikely(!event_file)) {
-		ret = -ENODEV;
-		goto out_unlock;
-	}
-
-	list_for_each_entry_rcu(test, &event_file->triggers, list) {
-		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
-			data = test;
-			break;
-		}
-	}
-	if (!data)
-		goto out_unlock;
+	if (n > 0)
+		seq_puts(m, "\n\n");
 
 	seq_puts(m, "# event histogram\n#\n# trigger info: ");
 	data->ops->print(m, data->ops, data);
-	seq_puts(m, "\n");
+	seq_puts(m, "#\n\n");
 
 	hist_data = data->private_data;
 	n_entries = print_entries(m, hist_data);
@@ -1070,6 +1055,27 @@ static int hist_show(struct seq_file *m, void *v)
 	seq_printf(m, "\nTotals:\n    Hits: %llu\n    Entries: %u\n    Dropped: %llu\n",
 		   (u64)atomic64_read(&hist_data->map->hits),
 		   n_entries, (u64)atomic64_read(&hist_data->map->drops));
+}
+
+static int hist_show(struct seq_file *m, void *v)
+{
+	struct event_trigger_data *data;
+	struct trace_event_file *event_file;
+	int n = 0, ret = 0;
+
+	mutex_lock(&event_mutex);
+
+	event_file = event_file_data(m->private);
+	if (unlikely(!event_file)) {
+		ret = -ENODEV;
+		goto out_unlock;
+	}
+
+	list_for_each_entry_rcu(data, &event_file->triggers, list) {
+		if (data->cmd_ops->trigger_type == ETT_EVENT_HIST)
+			hist_trigger_show(m, data, n++);
+	}
+
  out_unlock:
 	mutex_unlock(&event_mutex);
 
@@ -1233,6 +1239,54 @@ static void hist_clear(struct event_trigger_data *data)
 	data->paused = paused;
 }
 
+static bool hist_trigger_match(struct event_trigger_data *data,
+			       struct event_trigger_data *data_test)
+{
+	struct tracing_map_sort_key *sort_key, *sort_key_test;
+	struct hist_trigger_data *hist_data, *hist_data_test;
+	struct hist_field *key_field, *key_field_test;
+	unsigned int i;
+
+	hist_data = data->private_data;
+	hist_data_test = data_test->private_data;
+
+	if (hist_data->n_vals != hist_data_test->n_vals ||
+	    hist_data->n_fields != hist_data_test->n_fields ||
+	    hist_data->n_sort_keys != hist_data_test->n_sort_keys)
+		return false;
+
+	if ((data->filter_str && !data_test->filter_str) ||
+	    (!data->filter_str && data_test->filter_str))
+		return false;
+
+	for_each_hist_field(i, hist_data) {
+		key_field = hist_data->fields[i];
+		key_field_test = hist_data_test->fields[i];
+
+		if (key_field->flags != key_field_test->flags)
+			return false;
+		if (key_field->field != key_field_test->field)
+			return false;
+		if (key_field->offset != key_field_test->offset)
+			return false;
+	}
+
+	for (i = 0; i < hist_data->n_sort_keys; i++) {
+		sort_key = &hist_data->sort_keys[i];
+		sort_key_test = &hist_data_test->sort_keys[i];
+
+		if (sort_key->field_idx != sort_key_test->field_idx ||
+		    sort_key->descending != sort_key_test->descending)
+			return false;
+	}
+
+	if (data->filter_str &&
+	    (strcmp(data->filter_str, data_test->filter_str) != 0))
+		return false;
+
+	return true;
+}
+
 static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
 				 struct event_trigger_data *data,
 				 struct trace_event_file *file)
@@ -1243,6 +1297,8 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
 
 	list_for_each_entry_rcu(test, &file->triggers, list) {
 		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			if (!hist_trigger_match(data, test))
+				continue;
 			if (hist_data->attrs->pause)
 				test->paused = true;
 			else if (hist_data->attrs->cont)
@@ -1282,6 +1338,44 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
 	return ret;
 }
 
+static void hist_unregister_trigger(char *glob, struct event_trigger_ops *ops,
+				    struct event_trigger_data *data,
+				    struct trace_event_file *file)
+{
+	struct event_trigger_data *test;
+	bool unregistered = false;
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			if (!hist_trigger_match(data, test))
+				continue;
+			unregistered = true;
+			list_del_rcu(&test->list);
+			trace_event_trigger_enable_disable(file, 0);
+			update_cond_flag(file);
+			break;
+		}
+	}
+
+	if (unregistered && test->ops->free)
+		test->ops->free(test->ops, test);
+}
+
+static void hist_unreg_all(struct trace_event_file *file)
+{
+	struct event_trigger_data *test;
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			list_del_rcu(&test->list);
+			trace_event_trigger_enable_disable(file, 0);
+			update_cond_flag(file);
+			if (test->ops->free)
+				test->ops->free(test->ops, test);
+		}
+	}
+}
+
 static int event_hist_trigger_func(struct event_command *cmd_ops,
 				   struct trace_event_file *file,
 				   char *glob, char *cmd, char *param)
@@ -1331,22 +1425,19 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
 
 	trigger_data->private_data = hist_data;
 
+	/* if param is non-empty, it's supposed to be a filter */
+	if (param && cmd_ops->set_filter) {
+		ret = cmd_ops->set_filter(param, trigger_data, file);
+		if (ret < 0)
+			goto out_free;
+	}
+
 	if (glob[0] == '!') {
 		cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
 		ret = 0;
 		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:
 	ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
 	/*
 	 * The above returns on success the # of triggers registered,
@@ -1379,7 +1470,8 @@ static struct event_command trigger_hist_cmd = {
 	.flags			= EVENT_CMD_FL_NEEDS_REC,
 	.func			= event_hist_trigger_func,
 	.reg			= hist_register_trigger,
-	.unreg			= unregister_trigger,
+	.unreg			= hist_unregister_trigger,
+	.unreg_all		= hist_unreg_all,
 	.get_trigger_ops	= event_hist_get_trigger_ops,
 	.set_filter		= set_trigger_filter,
 };
@@ -1406,7 +1498,6 @@ hist_enable_trigger(struct event_trigger_data *data, void *rec)
 				test->paused = false;
 			else
 				test->paused = true;
-			break;
 		}
 	}
 }
@@ -1469,12 +1560,28 @@ hist_enable_get_trigger_ops(char *cmd, char *param)
 	return ops;
 }
 
+static void hist_enable_unreg_all(struct trace_event_file *file)
+{
+	struct event_trigger_data *test;
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_HIST_ENABLE) {
+			list_del_rcu(&test->list);
+			update_cond_flag(file);
+			trace_event_trigger_enable_disable(file, 0);
+			if (test->ops->free)
+				test->ops->free(test->ops, test);
+		}
+	}
+}
+
 static struct event_command trigger_hist_enable_cmd = {
 	.name			= ENABLE_HIST_STR,
 	.trigger_type		= ETT_HIST_ENABLE,
 	.func			= event_enable_trigger_func,
 	.reg			= event_enable_register_trigger,
 	.unreg			= event_enable_unregister_trigger,
+	.unreg_all		= hist_enable_unreg_all,
 	.get_trigger_ops	= hist_enable_get_trigger_ops,
 	.set_filter		= set_trigger_filter,
 };
@@ -1485,6 +1592,7 @@ static struct event_command trigger_hist_disable_cmd = {
 	.func			= event_enable_trigger_func,
 	.reg			= event_enable_register_trigger,
 	.unreg			= event_enable_unregister_trigger,
+	.unreg_all		= hist_enable_unreg_all,
 	.get_trigger_ops	= hist_enable_get_trigger_ops,
 	.set_filter		= set_trigger_filter,
 };