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Date: Thu, 12 Aug 2021 22:16:53 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-trace-devel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, Tom Zanussi <zanussi@...nel.org>,
Daniel Bristot de Oliveira <bristot@...hat.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
linux-rt-users <linux-rt-users@...r.kernel.org>,
Clark Williams <williams@...hat.com>,
"Steven Rostedt (VMware)" <rostedt@...dmis.org>
Subject: [PATCH 5/7] libtracefs: Add API tracefs_synth_save()
From: "Steven Rostedt (VMware)" <rostedt@...dmis.org>
Add an API tracefs_synth_save() that will save fields when onmax() or
onchange() handlers are executed.
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
Documentation/libtracefs-synth2.txt | 9 ++++
include/tracefs.h | 3 ++
src/tracefs-hist.c | 73 ++++++++++++++++++++++++++++-
3 files changed, 83 insertions(+), 2 deletions(-)
diff --git a/Documentation/libtracefs-synth2.txt b/Documentation/libtracefs-synth2.txt
index 194a4e021f62..cfcae7411f58 100644
--- a/Documentation/libtracefs-synth2.txt
+++ b/Documentation/libtracefs-synth2.txt
@@ -25,6 +25,9 @@ int tracefs_synth_trace(struct tracefs_synth pass:[*]synth,
enum tracefs_synth_handler type, const char pass:[*]var);
int tracefs_synth_snapshot(struct tracefs_synth pass:[*]synth,
enum tracefs_synth_handler type, const char pass:[*]var);
+int tracefs_synth_save(struct tracefs_synth pass:[*]synth,
+ enum tracefs_synth_handler type, const char pass:[*]var,
+ char pass:[**]save_fields);
--
DESCRIPTION
@@ -84,6 +87,12 @@ into a "snapshot" buffer, that can be accessed via the "snapshot" file in the
top level tracefs directory, or one of the instances. _var_ changes. _var_ must be one of
the _name_ elements used in *tracefs_synth_add_end_field*(3).
+*tracefs_synth_save*() When the given variable _var_ is either a new max if
+_handler_ is TRACEFS_SYNTH_HANDLE_MAX_ or simpy changed if TRACEFS_SYNTH_HANDLE_CHANGE_
+then saven the given _save_fields_ list. The fields will be stored in the histogram
+"hist" file of the event that can be retrieved with *tracefs_event_file_read*(3).
+_var_ changes. _var_ must be one of the _name_ elements used in *tracefs_synth_add_end_field*(3).
+
RETURN VALUE
------------
Returns zero on success or -1 on error.
diff --git a/include/tracefs.h b/include/tracefs.h
index 45a5bb2df2de..25abbdc10ebf 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -480,6 +480,9 @@ int tracefs_synth_trace(struct tracefs_synth *synth,
enum tracefs_synth_handler type, const char *field);
int tracefs_synth_snapshot(struct tracefs_synth *synth,
enum tracefs_synth_handler type, const char *field);
+int tracefs_synth_save(struct tracefs_synth *synth,
+ enum tracefs_synth_handler type, const char *field,
+ char **save_fields);
bool tracefs_synth_complete(struct tracefs_synth *synth);
struct tracefs_hist *tracefs_synth_get_start_hist(struct tracefs_synth *synth);
int tracefs_synth_create(struct tracefs_instance *instance,
diff --git a/src/tracefs-hist.c b/src/tracefs-hist.c
index 2c9c37b8ec23..003715fa693c 100644
--- a/src/tracefs-hist.c
+++ b/src/tracefs-hist.c
@@ -525,6 +525,7 @@ enum action_type {
ACTION_NONE,
ACTION_TRACE,
ACTION_SNAPSHOT,
+ ACTION_SAVE,
};
struct action {
@@ -532,6 +533,7 @@ struct action {
enum action_type type;
enum tracefs_synth_handler handler;
char *handle_field;
+ char *save;
};
/*
@@ -580,6 +582,13 @@ struct tracefs_synth {
int arg_cnt;
};
+static void action_free(struct action *action)
+{
+ free(action->handle_field);
+ free(action->save);
+ free(action);
+}
+
/**
* tracefs_synth_free - free the resources alloced to a synth
* @synth: The tracefs_synth descriptor
@@ -610,8 +619,7 @@ void tracefs_synth_free(struct tracefs_synth *synth)
while ((action = synth->actions)) {
synth->actions = action->next;
- free(action->handle_field);
- free(action);
+ action_free(action);
}
free(synth);
@@ -1445,6 +1453,64 @@ int tracefs_synth_snapshot(struct tracefs_synth *synth,
return 0;
}
+/**
+ * tracefs_synth_save - create a save command to the histogram
+ * @synth: The tracefs_synth descriptor
+ * @type: The type of handler to attach the save action
+ * @max_field: The field for handlers onmax and onchange
+ * @fields: The fields to save for the end variable
+ *
+ * Add the action to save fields for handlers onmax and onchange.
+ *
+ * Returns 0 on succes, -1 on error.
+ */
+int tracefs_synth_save(struct tracefs_synth *synth,
+ enum tracefs_synth_handler type, const char *max_field,
+ char **fields)
+{
+ struct action *action;
+ char *save;
+ int i;
+
+ if (!synth || !max_field || (type == TRACEFS_SYNTH_HANDLE_MATCH)) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ action = create_action(type, synth, max_field);
+ if (!action)
+ return -1;
+
+ action->type = ACTION_SAVE;
+ action->handler = type;
+ *synth->next_action = action;
+ synth->next_action = &action->next;
+
+ save = strdup(".save(");
+ if (!save)
+ goto error;
+
+ for (i = 0; fields[i]; i++) {
+ char *delim = i ? "," : NULL;
+
+ if (!trace_verify_event_field(synth->end_event, fields[i], NULL))
+ goto error;
+ save = append_string(save, delim, fields[i]);
+ }
+ save = append_string(save, NULL, ")");
+ if (!save)
+ goto error;
+
+ action->save = save;
+ add_action(synth, action);
+ return 0;
+ error:
+ action_free(action);
+ free(save);
+ return -1;
+ return 0;
+}
+
static char *create_synthetic_event(struct tracefs_synth *synth)
{
char *synthetic_event;
@@ -1596,6 +1662,9 @@ static char *create_actions(char *hist, struct tracefs_synth *synth)
case ACTION_SNAPSHOT:
hist = append_string(hist, NULL, ".snapshot()");
break;
+ case ACTION_SAVE:
+ hist = append_string(hist, NULL, action->save);
+ break;
default:
continue;
}
--
2.30.2
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