[28/54] tracing: Add hist trigger action hook

Commit Message

[e-mail] Aug. 29, 2018, 12:17 p.m. UTC

Add a hook for executing extra actions whenever a histogram entry is
added or updated.

The default 'action' when a hist entry is added to a histogram is to
update the set of values associated with it.  Some applications may
want to perform additional actions at that point, such as generate
another event, or compare and save a maximum.

Add a simple framework for doing that; specific actions will be
implemented on top of it in later patches.

Link: http://lkml.kernel.org/r/948[e-mail]

Signed-off-by: Tom Zanussi <[e-mail]>
Signed-off-by: Steven Rostedt (VMware) <[e-mail]>
(cherry picked from commit 0212e2aa30e112363aa559f30f6c24ae095f3e78)
Signed-off-by: Hirotaka MOTAI <[e-mail]>
---
 kernel/trace/trace_events_hist.c | 106 ++++++++++++++++++++++++++++++-
 1 file changed, 104 insertions(+), 2 deletions(-)

Patch

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index dbcdd2ff..68b9d6d3 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -28,16 +28,17 @@  struct hist_field;
 
 typedef u64 (*hist_field_fn_t) (struct hist_field *field,
 				struct tracing_map_elt *elt,
 				struct ring_buffer_event *rbe,
 				void *event);
 
 #define HIST_FIELD_OPERANDS_MAX	2
 #define HIST_FIELDS_MAX		(TRACING_MAP_FIELDS_MAX + TRACING_MAP_VARS_MAX)
+#define HIST_ACTIONS_MAX	8
 
 enum field_op_id {
 	FIELD_OP_NONE,
 	FIELD_OP_PLUS,
 	FIELD_OP_MINUS,
 	FIELD_OP_UNARY_MINUS,
 };
 
@@ -237,16 +238,19 @@  struct hist_trigger_attrs {
 	bool		cont;
 	bool		clear;
 	bool		ts_in_usecs;
 	unsigned int	map_bits;
 
 	char		*assignment_str[TRACING_MAP_VARS_MAX];
 	unsigned int	n_assignments;
 
+	char		*action_str[HIST_ACTIONS_MAX];
+	unsigned int	n_actions;
+
 	struct var_defs	var_defs;
 };
 
 struct hist_trigger_data {
 	struct hist_field               *fields[HIST_FIELDS_MAX];
 	unsigned int			n_vals;
 	unsigned int			n_keys;
 	unsigned int			n_fields;
@@ -256,16 +260,31 @@  struct hist_trigger_data {
 	unsigned int			n_sort_keys;
 	struct trace_event_file		*event_file;
 	struct hist_trigger_attrs	*attrs;
 	struct tracing_map		*map;
 	bool				enable_timestamps;
 	bool				remove;
 	struct hist_field               *var_refs[TRACING_MAP_VARS_MAX];
 	unsigned int			n_var_refs;
+
+	struct action_data		*actions[HIST_ACTIONS_MAX];
+	unsigned int			n_actions;
+};
+
+struct action_data;
+
+typedef void (*action_fn_t) (struct hist_trigger_data *hist_data,
+			     struct tracing_map_elt *elt, void *rec,
+			     struct ring_buffer_event *rbe,
+			     struct action_data *data, u64 *var_ref_vals);
+
+struct action_data {
+	action_fn_t		fn;
+	unsigned int		var_ref_idx;
 };
 
 static u64 hist_field_timestamp(struct hist_field *hist_field,
 				struct tracing_map_elt *elt,
 				struct ring_buffer_event *rbe,
 				void *event)
 {
 	struct hist_trigger_data *hist_data = hist_field->hist_data;
@@ -759,23 +778,36 @@  static void destroy_hist_trigger_attrs(struct hist_trigger_attrs *attrs)
 	unsigned int i;
 
 	if (!attrs)
 		return;
 
 	for (i = 0; i < attrs->n_assignments; i++)
 		kfree(attrs->assignment_str[i]);
 
+	for (i = 0; i < attrs->n_actions; i++)
+		kfree(attrs->action_str[i]);
+
 	kfree(attrs->name);
 	kfree(attrs->sort_key_str);
 	kfree(attrs->keys_str);
 	kfree(attrs->vals_str);
 	kfree(attrs);
 }
 
+static int parse_action(char *str, struct hist_trigger_attrs *attrs)
+{
+	int ret = 0;
+
+	if (attrs->n_actions >= HIST_ACTIONS_MAX)
+		return ret;
+
+	return ret;
+}
+
 static int parse_assignment(char *str, struct hist_trigger_attrs *attrs)
 {
 	int ret = 0;
 
 	if ((strncmp(str, "key=", strlen("key=")) == 0) ||
 	    (strncmp(str, "keys=", strlen("keys=")) == 0)) {
 		attrs->keys_str = kstrdup(str, GFP_KERNEL);
 		if (!attrs->keys_str) {
@@ -849,18 +881,19 @@  static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str)
 		} else if (strcmp(str, "pause") == 0)
 			attrs->pause = true;
 		else if ((strcmp(str, "cont") == 0) ||
 			 (strcmp(str, "continue") == 0))
 			attrs->cont = true;
 		else if (strcmp(str, "clear") == 0)
 			attrs->clear = true;
 		else {
-			ret = -EINVAL;
-			goto free;
+			ret = parse_action(str, attrs);
+			if (ret)
+				goto free;
 		}
 	}
 
 	if (!attrs->keys_str) {
 		ret = -EINVAL;
 		goto free;
 	}
 
@@ -2042,21 +2075,65 @@  static int create_sort_keys(struct hist_trigger_data *hist_data)
 		}
 	}
 
 	hist_data->n_sort_keys = i;
  out:
 	return ret;
 }
 
+static void destroy_actions(struct hist_trigger_data *hist_data)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_actions; i++) {
+		struct action_data *data = hist_data->actions[i];
+
+		kfree(data);
+	}
+}
+
+static int parse_actions(struct hist_trigger_data *hist_data)
+{
+	unsigned int i;
+	int ret = 0;
+	char *str;
+
+	for (i = 0; i < hist_data->attrs->n_actions; i++) {
+		str = hist_data->attrs->action_str[i];
+	}
+
+	return ret;
+}
+
+static int create_actions(struct hist_trigger_data *hist_data,
+			  struct trace_event_file *file)
+{
+	struct action_data *data;
+	unsigned int i;
+	int ret = 0;
+
+	for (i = 0; i < hist_data->attrs->n_actions; i++) {
+		data = hist_data->actions[i];
+	}
+
+	return ret;
+}
+
 static void destroy_hist_data(struct hist_trigger_data *hist_data)
 {
+	if (!hist_data)
+		return;
+
 	destroy_hist_trigger_attrs(hist_data->attrs);
 	destroy_hist_fields(hist_data);
 	tracing_map_destroy(hist_data->map);
+
+	destroy_actions(hist_data);
+
 	kfree(hist_data);
 }
 
 static int create_tracing_map_fields(struct hist_trigger_data *hist_data)
 {
 	struct tracing_map *map = hist_data->map;
 	struct ftrace_event_field *field;
 	struct hist_field *hist_field;
@@ -2113,16 +2190,20 @@  create_hist_data(unsigned int map_bits,
 	hist_data = kzalloc(sizeof(*hist_data), GFP_KERNEL);
 	if (!hist_data)
 		return ERR_PTR(-ENOMEM);
 
 	hist_data->attrs = attrs;
 	hist_data->remove = remove;
 	hist_data->event_file = file;
 
+	ret = parse_actions(hist_data);
+	if (ret)
+		goto free;
+
 	ret = create_hist_fields(hist_data, file);
 	if (ret)
 		goto free;
 
 	ret = create_sort_keys(hist_data);
 	if (ret)
 		goto free;
 
@@ -2204,16 +2285,30 @@  static inline void add_to_key(char *compound_key, void *key,
 		/* ensure NULL-termination */
 		if (size > key_field->size - 1)
 			size = key_field->size - 1;
 	}
 
 	memcpy(compound_key + key_field->offset, key, size);
 }
 
+static void
+hist_trigger_actions(struct hist_trigger_data *hist_data,
+		     struct tracing_map_elt *elt, void *rec,
+		     struct ring_buffer_event *rbe, u64 *var_ref_vals)
+{
+	struct action_data *data;
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_actions; i++) {
+		data = hist_data->actions[i];
+		data->fn(hist_data, elt, rec, rbe, data, var_ref_vals);
+	}
+}
+
 static void event_hist_trigger(struct event_trigger_data *data, void *rec,
 			       struct ring_buffer_event *rbe)
 {
 	struct hist_trigger_data *hist_data = data->private_data;
 	bool use_compound_key = (hist_data->n_keys > 1);
 	unsigned long entries[HIST_STACKTRACE_DEPTH];
 	u64 var_ref_vals[TRACING_MAP_VARS_MAX];
 	char compound_key[HIST_KEY_SIZE_MAX];
@@ -2259,16 +2354,19 @@  static void event_hist_trigger(struct event_trigger_data *data, void *rec,
 	    !resolve_var_refs(hist_data, key, var_ref_vals, false))
 		return;
 
 	elt = tracing_map_insert(hist_data->map, key);
 	if (!elt)
 		return;
 
 	hist_trigger_elt_update(hist_data, elt, rec, rbe, var_ref_vals);
+
+	if (resolve_var_refs(hist_data, key, var_ref_vals, true))
+		hist_trigger_actions(hist_data, elt, rec, rbe, var_ref_vals);
 }
 
 static void hist_trigger_stacktrace_print(struct seq_file *m,
 					  unsigned long *stacktrace_entries,
 					  unsigned int max_entries)
 {
 	char str[KSYM_SYMBOL_LEN];
 	unsigned int spaces = 8;
@@ -3043,16 +3141,20 @@  static int event_hist_trigger_func(struct event_command *cmd_ops,
 		goto out_free;
 
 	if (get_named_trigger_data(trigger_data))
 		goto enable;
 
 	if (has_hist_vars(hist_data))
 		save_hist_vars(hist_data);
 
+	ret = create_actions(hist_data, file);
+	if (ret)
+		goto out_unreg;
+
 	ret = tracing_map_init(hist_data->map);
 	if (ret)
 		goto out_unreg;
 enable:
 	ret = hist_trigger_enable(trigger_data, file);
 	if (ret)
 		goto out_unreg;