tracing: Add hist trigger support for multiple values ('vals=' param)

Allow users to specify trace event fields to use in aggregated sums
via a new 'vals=' keyword.  Before this addition, the only aggregated
sum supported was the implied value 'hitcount'.  With this addition,
'hitcount' is also supported as an explicit value field, as is any
numeric trace event field.

This expands the hist trigger syntax from this:

  # echo hist:keys=xxx [ if filter] > event/trigger

to this:

  # echo hist:keys=xxx:vals=yyy [ if filter] > event/trigger

Link: http://lkml.kernel.org/r/2a5d1adb5ba6c65d7bb2148e379f2fed47f29a68.1457029949.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>

1 files changed, 78 insertions, 1 deletions

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 23b45e462117..1b33590b9c8f 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -84,6 +84,7 @@ enum hist_field_flags {
 
 struct hist_trigger_attrs {
 	char		*keys_str;
+	char		*vals_str;
 	unsigned int	map_bits;
 };
 
@@ -165,6 +166,7 @@ static void destroy_hist_trigger_attrs(struct hist_trigger_attrs *attrs)
 		return;
 
 	kfree(attrs->keys_str);
+	kfree(attrs->vals_str);
 	kfree(attrs);
 }
 
@@ -183,6 +185,10 @@ static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str)
 		if ((strncmp(str, "key=", strlen("key=")) == 0) ||
 		    (strncmp(str, "keys=", strlen("keys=")) == 0))
 			attrs->keys_str = kstrdup(str, GFP_KERNEL);
+		else if ((strncmp(str, "val=", strlen("val=")) == 0) ||
+			 (strncmp(str, "vals=", strlen("vals=")) == 0) ||
+			 (strncmp(str, "values=", strlen("values=")) == 0))
+			attrs->vals_str = kstrdup(str, GFP_KERNEL);
 		else if (strncmp(str, "size=", strlen("size=")) == 0) {
 			int map_bits = parse_map_size(str);
 
@@ -276,13 +282,70 @@ static int create_hitcount_val(struct hist_trigger_data *hist_data)
 	return 0;
 }
 
+static int create_val_field(struct hist_trigger_data *hist_data,
+			    unsigned int val_idx,
+			    struct trace_event_file *file,
+			    char *field_str)
+{
+	struct ftrace_event_field *field = NULL;
+	unsigned long flags = 0;
+	int ret = 0;
+
+	if (WARN_ON(val_idx >= TRACING_MAP_VALS_MAX))
+		return -EINVAL;
+	field = trace_find_event_field(file->event_call, field_str);
+	if (!field) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	hist_data->fields[val_idx] = create_hist_field(field, flags);
+	if (!hist_data->fields[val_idx]) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	++hist_data->n_vals;
+
+	if (WARN_ON(hist_data->n_vals > TRACING_MAP_VALS_MAX))
+		ret = -EINVAL;
+ out:
+	return ret;
+}
+
 static int create_val_fields(struct hist_trigger_data *hist_data,
 			     struct trace_event_file *file)
 {
+	char *fields_str, *field_str;
+	unsigned int i, j;
 	int ret;
 
 	ret = create_hitcount_val(hist_data);
+	if (ret)
+		goto out;
 
+	fields_str = hist_data->attrs->vals_str;
+	if (!fields_str)
+		goto out;
+
+	strsep(&fields_str, "=");
+	if (!fields_str)
+		goto out;
+
+	for (i = 0, j = 1; i < TRACING_MAP_VALS_MAX &&
+		     j < TRACING_MAP_VALS_MAX; i++) {
+		field_str = strsep(&fields_str, ",");
+		if (!field_str)
+			break;
+		if (strcmp(field_str, "hitcount") == 0)
+			continue;
+		ret = create_val_field(hist_data, j++, file, field_str);
+		if (ret)
+			goto out;
+	}
+	if (fields_str && (strcmp(fields_str, "hitcount") != 0))
+		ret = -EINVAL;
+ out:
 	return ret;
 }
 
@@ -552,6 +615,12 @@ hist_trigger_entry_print(struct seq_file *m,
 	seq_printf(m, " hitcount: %10llu",
 		   tracing_map_read_sum(elt, HITCOUNT_IDX));
 
+	for (i = 1; i < hist_data->n_vals; i++) {
+		seq_printf(m, "  %s: %10llu",
+			   hist_data->fields[i]->field->name,
+			   tracing_map_read_sum(elt, i));
+	}
+
 	seq_puts(m, "\n");
 }
 
@@ -659,7 +728,15 @@ static int event_hist_trigger_print(struct seq_file *m,
 	}
 
 	seq_puts(m, ":vals=");
-	seq_puts(m, "hitcount");
+
+	for_each_hist_val_field(i, hist_data) {
+		if (i == HITCOUNT_IDX)
+			seq_puts(m, "hitcount");
+		else {
+			seq_puts(m, ",");
+			hist_field_print(m, hist_data->fields[i]);
+		}
+	}
 
 	seq_puts(m, ":sort=");
 	seq_puts(m, "hitcount");