[PATCH v3] libtracefs: New APIs for getting the raw format of synth event

[PATCH v3] libtracefs: New APIs for getting the raw format of synth event

[Yordan Karadzhov (VMware)]

The following APIs are added:
int tracefs_synth_echo_fmt(struct trace_seq *, struct tracefs_synth *)
const char *tracefs_synth_show_event(struct tracefs_synth *)
const char *tracefs_synth_show_start_hist(struct tracefs_synth *)
const char *tracefs_synth_show_end_hist(struct tracefs_synth *)

The new APIs can be useful in the case whene the user wants to
check what exactly gets passed to the kernel as definition of
a synth event.

Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
---
 Documentation/libtracefs-synth2.txt | 23 ++++++-
 include/tracefs.h                   |  5 ++
 src/tracefs-hist.c                  | 94 +++++++++++++++++++++++------
 3 files changed, 102 insertions(+), 20 deletions(-)

diff --git a/Documentation/libtracefs-synth2.txt b/Documentation/libtracefs-synth2.txt
index 569819a..e557bc9 100644
--- a/Documentation/libtracefs-synth2.txt
+++ b/Documentation/libtracefs-synth2.txt
@@ -5,7 +5,8 @@ NAME
 ----
 tracefs_synth_create, tracefs_synth_destroy, tracefs_synth_echo_cmd, tracefs_synth_complete,
 tracefs_synth_get_start_hist, tracefs_synth_trace, tracefs_synth_snapshot,
-tracefs_synth_get_name - Creation of synthetic events
+tracefs_synth_get_name, tracefs_synth_echo_fmt, tracefs_synth_show_event,
+tracefs_synth_show_start_hist, tracefs_synth_show_end_hist - Creation of synthetic events
 
 SYNOPSIS
 --------
@@ -27,6 +28,11 @@ int tracefs_synth_save(struct tracefs_synth pass:[*]synth,
 		       enum tracefs_synth_handler type, const char pass:[*]var,
 		       char pass:[**]save_fields);
 const char *tracefs_synth_get_name(struct tracefs_synth pass:[*]synth);
+int tracefs_synth_echo_fmt(struct trace_seq pass:[*]seq, struct tracefs_synth pass:[*]synth);
+const char *tracefs_synth_show_event(struct tracefs_synth pass:[*]synth);
+const char *tracefs_synth_show_start_hist(struct tracefs_synth pass:[*]synth);
+const char *tracefs_synth_show_end_hist(struct tracefs_synth pass:[*]synth);
+
 --
 
 DESCRIPTION
@@ -93,9 +99,22 @@ _var_ changes. _var_ must be one of the _name_ elements used in *tracefs_synth_a
 The returned string belongs to the synth event object and is freed with the event
 by *tracefs_synth_free*().
 
+*tracefs_synth_show_event*() returns the format of the dynamic event used by the synthetic
+event or NULL on error. The returned string belongs to the synth event object and is freed
+with the event by *tracefs_synth_free*().
+
+*tracefs_synth_show_start_hist*() returns the format of the start histogram used by the
+synthetic event or NULL on error. The returned string belongs to the synth event object
+and is freed with the event by *tracefs_synth_free*().
+
+*tracefs_synth_show_end_hist*() returns the format of the end histogram used by the
+synthetic event or NULL on error. The returned string belongs to the synth event object
+and is freed with the event by *tracefs_synth_free*().
+
 RETURN VALUE
 ------------
-*tracefs_synth_get_name*() returns a string owned by the synth event object.
+*tracefs_synth_get_name*(), *tracefs_synth_show_event*(), *tracefs_synth_show_start_hist*()
+and *tracefs_synth_show_end_hist*()  return a string owned by the synth event object.
 
 All other functions return zero on success or -1 on error.
 
diff --git a/include/tracefs.h b/include/tracefs.h
index 967690f..b772f5a 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -250,6 +250,7 @@ enum tracefs_dynevent_type {
 	TRACEFS_DYNEVENT_SYNTH		= 1 << 5,
 	TRACEFS_DYNEVENT_MAX		= 1 << 6,
 };
+
 int tracefs_dynevent_create(struct tracefs_dynevent *devent);
 int tracefs_dynevent_destroy(struct tracefs_dynevent *devent, bool force);
 int tracefs_dynevent_destroy_all(unsigned int types, bool force);
@@ -550,6 +551,10 @@ int tracefs_synth_create(struct tracefs_synth *synth);
 int tracefs_synth_destroy(struct tracefs_synth *synth);
 void tracefs_synth_free(struct tracefs_synth *synth);
 int tracefs_synth_echo_cmd(struct trace_seq *seq, struct tracefs_synth *synth);
+int tracefs_synth_echo_fmt(struct trace_seq *seq, struct tracefs_synth *synth);
+const char *tracefs_synth_show_event(struct tracefs_synth *synth);
+const char *tracefs_synth_show_start_hist(struct tracefs_synth *synth);
+const char *tracefs_synth_show_end_hist(struct tracefs_synth *synth);
 
 struct tracefs_synth *tracefs_sql(struct tep_handle *tep, const char *name,
 				  const char *sql_buffer, char **err);
diff --git a/src/tracefs-hist.c b/src/tracefs-hist.c
index 6051ecc..f5359a5 100644
--- a/src/tracefs-hist.c
+++ b/src/tracefs-hist.c
@@ -683,6 +683,8 @@ struct tracefs_synth {
 	struct action		*actions;
 	struct action		**next_action;
 	struct tracefs_dynevent	*dyn_event;
+	char			*start_hist;
+	char			*end_hist;
 	char			*name;
 	char			**synthetic_fields;
 	char			**synthetic_args;
@@ -737,6 +739,8 @@ void tracefs_synth_free(struct tracefs_synth *synth)
 		return;
 
 	free(synth->name);
+	free(synth->start_hist);
+	free(synth->end_hist);
 	tracefs_list_free(synth->synthetic_fields);
 	tracefs_list_free(synth->synthetic_args);
 	tracefs_list_free(synth->start_keys);
@@ -1802,6 +1806,67 @@ static char *create_end_hist(struct tracefs_synth *synth)
 	return create_actions(end_hist, synth);
 }
 
+/*
+ * tracefs_synth_echo_fmt - show the raw format of a synthetic event
+ * @seq: A trace_seq to store the format string
+ * @synth: The synthetic event to read format from
+ *
+ * This shows the raw format that describes the synthetic event, including
+ * the format of the dynamic event and the start / end histograms.
+ *
+ * Returns 0 on succes -1 on error.
+ */
+int tracefs_synth_echo_fmt(struct trace_seq *seq, struct tracefs_synth *synth)
+{
+	if (!synth->dyn_event)
+		return -1;
+
+	trace_seq_printf(seq, "%s", synth->dyn_event->format);
+	trace_seq_printf(seq, "\n%s", synth->start_hist);
+	trace_seq_printf(seq, "\n%s", synth->end_hist);
+
+	return 0;
+}
+
+/*
+ * tracefs_synth_show_event - show the dynamic event used by a synth event
+ * @synth: The synthetic event to read format from
+ *
+ * This shows the raw format of the dynamic event used by the synthetic event.
+ *
+ * Returns format string owned by @synth on success, or NULL on error.
+ */
+const char *tracefs_synth_show_event(struct tracefs_synth *synth)
+{
+	return synth->dyn_event ? synth->dyn_event->format : NULL;
+}
+
+/*
+ * tracefs_synth_show_start_hist - show the start histogram used by a synth event
+ * @synth: The synthetic event to read format from
+ *
+ * This shows the raw format of the start histogram used by the synthetic event.
+ *
+ * Returns format string owned by @synth on success, or NULL on error.
+ */
+const char *tracefs_synth_show_start_hist(struct tracefs_synth *synth)
+{
+	return synth->start_hist;
+}
+
+/*
+ * tracefs_synth_show_end_hist - show the end histogram used by a synth event
+ * @synth: The synthetic event to read format from
+ *
+ * This shows the raw format of the end histogram used by the synthetic event.
+ *
+ * Returns format string owned by @synth on success, or NULL on error.
+ */
+const char *tracefs_synth_show_end_hist(struct tracefs_synth *synth)
+{
+	return synth->end_hist;
+}
+
 static char *append_filter(char *hist, char *filter, unsigned int parens)
 {
 	int i;
@@ -1940,8 +2005,6 @@ tracefs_synth_get_start_hist(struct tracefs_synth *synth)
  */
 int tracefs_synth_create(struct tracefs_synth *synth)
 {
-	char *start_hist = NULL;
-	char *end_hist = NULL;
 	int ret;
 
 	if (!synth) {
@@ -1962,40 +2025,35 @@ int tracefs_synth_create(struct tracefs_synth *synth)
 	if (tracefs_dynevent_create(synth->dyn_event))
 		return -1;
 
-	start_hist = create_hist(synth->start_keys, synth->start_vars);
-	start_hist = append_filter(start_hist, synth->start_filter,
-				   synth->start_parens);
-	if (!start_hist)
+	synth->start_hist = create_hist(synth->start_keys, synth->start_vars);
+	synth->start_hist = append_filter(synth->start_hist, synth->start_filter,
+					  synth->start_parens);
+	if (!synth->start_hist)
 		goto remove_synthetic;
 
-	end_hist = create_end_hist(synth);
-	end_hist = append_filter(end_hist, synth->end_filter,
-				   synth->end_parens);
-	if (!end_hist)
+	synth->end_hist = create_end_hist(synth);
+	synth->end_hist = append_filter(synth->end_hist, synth->end_filter,
+					synth->end_parens);
+	if (!synth->end_hist)
 		goto remove_synthetic;
 
 	ret = tracefs_event_file_append(synth->instance, synth->start_event->system,
 					synth->start_event->name,
-					"trigger", start_hist);
+					"trigger", synth->start_hist);
 	if (ret < 0)
 		goto remove_synthetic;
 
 	ret = tracefs_event_file_append(synth->instance, synth->end_event->system,
 					synth->end_event->name,
-					"trigger", end_hist);
+					"trigger", synth->end_hist);
 	if (ret < 0)
 		goto remove_start_hist;
 
-	free(start_hist);
-	free(end_hist);
-
 	return 0;
 
  remove_start_hist:
-	remove_hist(synth->instance, synth->start_event, start_hist);
+	remove_hist(synth->instance, synth->start_event, synth->start_hist);
  remove_synthetic:
-	free(end_hist);
-	free(start_hist);
 	tracefs_dynevent_destroy(synth->dyn_event, false);
 	return -1;
 }
-- 
2.32.0

Re: [PATCH v3] libtracefs: New APIs for getting the raw format of synth event

[Steven Rostedt]

On Thu,  9 Dec 2021 18:38:15 +0200
"Yordan Karadzhov (VMware)" <y.karadz@gmail.com> wrote:

> The following APIs are added:
> int tracefs_synth_echo_fmt(struct trace_seq *, struct tracefs_synth *)
> const char *tracefs_synth_show_event(struct tracefs_synth *)
> const char *tracefs_synth_show_start_hist(struct tracefs_synth *)
> const char *tracefs_synth_show_end_hist(struct tracefs_synth *)
> 
> The new APIs can be useful in the case whene the user wants to

                                        "where"

> check what exactly gets passed to the kernel as definition of
> a synth event.
> 
> Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
> ---
>  Documentation/libtracefs-synth2.txt | 23 ++++++-
>  include/tracefs.h                   |  5 ++
>  src/tracefs-hist.c                  | 94 +++++++++++++++++++++++------
>  3 files changed, 102 insertions(+), 20 deletions(-)
> 
> diff --git a/Documentation/libtracefs-synth2.txt b/Documentation/libtracefs-synth2.txt
> index 569819a..e557bc9 100644
> --- a/Documentation/libtracefs-synth2.txt
> +++ b/Documentation/libtracefs-synth2.txt
> @@ -5,7 +5,8 @@ NAME
>  ----
>  tracefs_synth_create, tracefs_synth_destroy, tracefs_synth_echo_cmd, tracefs_synth_complete,
>  tracefs_synth_get_start_hist, tracefs_synth_trace, tracefs_synth_snapshot,
> -tracefs_synth_get_name - Creation of synthetic events
> +tracefs_synth_get_name, tracefs_synth_echo_fmt, tracefs_synth_show_event,
> +tracefs_synth_show_start_hist, tracefs_synth_show_end_hist - Creation of synthetic events
>  
>  SYNOPSIS
>  --------
> @@ -27,6 +28,11 @@ int tracefs_synth_save(struct tracefs_synth pass:[*]synth,
>  		       enum tracefs_synth_handler type, const char pass:[*]var,
>  		       char pass:[**]save_fields);
>  const char *tracefs_synth_get_name(struct tracefs_synth pass:[*]synth);
> +int tracefs_synth_echo_fmt(struct trace_seq pass:[*]seq, struct tracefs_synth pass:[*]synth);
> +const char *tracefs_synth_show_event(struct tracefs_synth pass:[*]synth);
> +const char *tracefs_synth_show_start_hist(struct tracefs_synth pass:[*]synth);
> +const char *tracefs_synth_show_end_hist(struct tracefs_synth pass:[*]synth);
> +
>  --
>  
>  DESCRIPTION
> @@ -93,9 +99,22 @@ _var_ changes. _var_ must be one of the _name_ elements used in *tracefs_synth_a
>  The returned string belongs to the synth event object and is freed with the event
>  by *tracefs_synth_free*().
>  
> +*tracefs_synth_show_event*() returns the format of the dynamic event used by the synthetic
> +event or NULL on error. The returned string belongs to the synth event object and is freed
> +with the event by *tracefs_synth_free*().
> +
> +*tracefs_synth_show_start_hist*() returns the format of the start histogram used by the
> +synthetic event or NULL on error. The returned string belongs to the synth event object
> +and is freed with the event by *tracefs_synth_free*().
> +
> +*tracefs_synth_show_end_hist*() returns the format of the end histogram used by the
> +synthetic event or NULL on error. The returned string belongs to the synth event object
> +and is freed with the event by *tracefs_synth_free*().
> +
>  RETURN VALUE
>  ------------
> -*tracefs_synth_get_name*() returns a string owned by the synth event object.
> +*tracefs_synth_get_name*(), *tracefs_synth_show_event*(), *tracefs_synth_show_start_hist*()
> +and *tracefs_synth_show_end_hist*()  return a string owned by the synth event object.
>  
>  All other functions return zero on success or -1 on error.
>  
> diff --git a/include/tracefs.h b/include/tracefs.h
> index 967690f..b772f5a 100644
> --- a/include/tracefs.h
> +++ b/include/tracefs.h
> @@ -250,6 +250,7 @@ enum tracefs_dynevent_type {
>  	TRACEFS_DYNEVENT_SYNTH		= 1 << 5,
>  	TRACEFS_DYNEVENT_MAX		= 1 << 6,
>  };
> +
>  int tracefs_dynevent_create(struct tracefs_dynevent *devent);
>  int tracefs_dynevent_destroy(struct tracefs_dynevent *devent, bool force);
>  int tracefs_dynevent_destroy_all(unsigned int types, bool force);
> @@ -550,6 +551,10 @@ int tracefs_synth_create(struct tracefs_synth *synth);
>  int tracefs_synth_destroy(struct tracefs_synth *synth);
>  void tracefs_synth_free(struct tracefs_synth *synth);
>  int tracefs_synth_echo_cmd(struct trace_seq *seq, struct tracefs_synth *synth);
> +int tracefs_synth_echo_fmt(struct trace_seq *seq, struct tracefs_synth *synth);
> +const char *tracefs_synth_show_event(struct tracefs_synth *synth);
> +const char *tracefs_synth_show_start_hist(struct tracefs_synth *synth);
> +const char *tracefs_synth_show_end_hist(struct tracefs_synth *synth);
>  
>  struct tracefs_synth *tracefs_sql(struct tep_handle *tep, const char *name,
>  				  const char *sql_buffer, char **err);
> diff --git a/src/tracefs-hist.c b/src/tracefs-hist.c
> index 6051ecc..f5359a5 100644
> --- a/src/tracefs-hist.c
> +++ b/src/tracefs-hist.c
> @@ -683,6 +683,8 @@ struct tracefs_synth {
>  	struct action		*actions;
>  	struct action		**next_action;
>  	struct tracefs_dynevent	*dyn_event;
> +	char			*start_hist;
> +	char			*end_hist;
>  	char			*name;
>  	char			**synthetic_fields;
>  	char			**synthetic_args;
> @@ -737,6 +739,8 @@ void tracefs_synth_free(struct tracefs_synth *synth)
>  		return;
>  
>  	free(synth->name);
> +	free(synth->start_hist);
> +	free(synth->end_hist);
>  	tracefs_list_free(synth->synthetic_fields);
>  	tracefs_list_free(synth->synthetic_args);
>  	tracefs_list_free(synth->start_keys);
> @@ -1802,6 +1806,67 @@ static char *create_end_hist(struct tracefs_synth *synth)
>  	return create_actions(end_hist, synth);
>  }
>  
> +/*
> + * tracefs_synth_echo_fmt - show the raw format of a synthetic event
> + * @seq: A trace_seq to store the format string
> + * @synth: The synthetic event to read format from
> + *
> + * This shows the raw format that describes the synthetic event, including
> + * the format of the dynamic event and the start / end histograms.
> + *
> + * Returns 0 on succes -1 on error.
> + */
> +int tracefs_synth_echo_fmt(struct trace_seq *seq, struct tracefs_synth *synth)


Sorry to nitpick on the naming again, but perhaps we should call this

  tracefs_synth_raw_fmt()

Because saying "echo_fmt" I would think it would include the "echo" command
in the output.


> +{
> +	if (!synth->dyn_event)
> +		return -1;
> +
> +	trace_seq_printf(seq, "%s", synth->dyn_event->format);
> +	trace_seq_printf(seq, "\n%s", synth->start_hist);
> +	trace_seq_printf(seq, "\n%s", synth->end_hist);

Hmm, shouldn't this end with a \n? Or is it to allow quoting?

-- Steve


> +
> +	return 0;
> +}
> +

Re: [PATCH v3] libtracefs: New APIs for getting the raw format of synth event

[Yordan Karadzhov]

On 9.12.21 г. 20:24 ч., Steven Rostedt wrote:
>> +/*
>> + * tracefs_synth_echo_fmt - show the raw format of a synthetic event
>> + * @seq: A trace_seq to store the format string
>> + * @synth: The synthetic event to read format from
>> + *
>> + * This shows the raw format that describes the synthetic event, including
>> + * the format of the dynamic event and the start / end histograms.
>> + *
>> + * Returns 0 on succes -1 on error.
>> + */
>> +int tracefs_synth_echo_fmt(struct trace_seq *seq, struct tracefs_synth *synth)
> 
> Sorry to nitpick on the naming again, but perhaps we should call this
> 
>    tracefs_synth_raw_fmt()
> 
> Because saying "echo_fmt" I would think it would include the "echo" command
> in the output.
> 

OK

> 
>> +{
>> +	if (!synth->dyn_event)
>> +		return -1;
>> +
>> +	trace_seq_printf(seq, "%s", synth->dyn_event->format);
>> +	trace_seq_printf(seq, "\n%s", synth->start_hist);
>> +	trace_seq_printf(seq, "\n%s", synth->end_hist);
> Hmm, shouldn't this end with a \n? Or is it to allow quoting?

The function returns string and the user is free to do anything with it. If this string ends with "\n" and you print 
this string with puts() you will get extra line (same problem printing it in Python).


Thanks!
Y.

> 
> -- Steve
> 
> 
>> +
>> +	return 0;
>> +}
>> +

Re: [PATCH v3] libtracefs: New APIs for getting the raw format of synth event

[Steven Rostedt]

On Thu, 9 Dec 2021 21:07:28 +0200
Yordan Karadzhov <y.karadz@gmail.com> wrote:

> > Hmm, shouldn't this end with a \n? Or is it to allow quoting?  
> 
> The function returns string and the user is free to do anything with it. If this string ends with "\n" and you print 
> this string with puts() you will get extra line (same problem printing it in Python).

OK, that's fine.

-- Steve