[PATCH v4 00/10] libtracefs dynamic events support

[PATCH v4 00/10] libtracefs dynamic events support

[Tzvetomir Stoyanov (VMware)]

The libtracefs logic that works with ftrace dynamic events is unified
and capsulated into a new set of dynamic events APIs. This change makes
the code more consistent and reusable. Also, adding future libtracefs
support for uprobes and eprobes dynamic events is simplified.
The existing library APIs for kprobes and synthetic events are
reimplemented using the new dynamic events helpers.

This patch sets depends on "[PATCH v2 0/4] Modifications of some 'hist' APIs":
 https://lore.kernel.org/linux-trace-devel/20210924095702.151826-1-y.karadz@gmail.com/

Suggested-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>

v4 changes:
 - Redefined the dynamic events enum, so the items can be used in a bitmask.
 - Reimplement the logic for parsing dynamic event strings from ftrace files.
 - Coding style fixes.
 - Added more comments.

v3 changes:
 - Exposed dynamic events API as official tracefs APIs.
 - Removed kprobe specific APIs, that duplicate corresponding dynamic events
   APIs.
 - Updated unit tests and man pages with the new dynamic events APIs.
 - Fixed typos, found by Yordan. 

v2 changes:
 - Removed triple pointer from the APIs.
 - Reimplement dynamic events parsing using strtok_r instead of strchr.
 - Coding style fixes.


Tzvetomir Stoyanov (VMware) (10):
  libtracefs: New APIs for dynamic events
  libtracefs: New APIs for kprobe allocation
  libtracefs: Remove redundant kprobes APIs
  libtracefs: Change tracefs_kprobe_info API
  libtracefs: Reimplement kprobe raw APIs
  libtracefs: Extend kprobes unit test
  libtracefs: Rename tracefs_synth_init API
  libtracefs: Use the internal dynamic events API when creating
    synthetic events
  libtracefs: Update kprobes man pages
  libtracefs: Document dynamic events APIs

 Documentation/libtracefs-dynevents.txt | 251 +++++++++
 Documentation/libtracefs-kprobes.txt   | 111 ++--
 Documentation/libtracefs-synth.txt     |  20 +-
 Documentation/libtracefs-synth2.txt    |  10 +-
 Documentation/libtracefs.txt           |  17 +
 include/tracefs-local.h                |  18 +
 include/tracefs.h                      |  54 +-
 src/Makefile                           |   1 +
 src/tracefs-dynevents.c                | 689 +++++++++++++++++++++++++
 src/tracefs-hist.c                     | 125 +++--
 src/tracefs-kprobes.c                  | 530 ++++++-------------
 src/tracefs-sqlhist.c                  |   6 +-
 utest/tracefs-utest.c                  | 412 +++++++++------
 13 files changed, 1535 insertions(+), 709 deletions(-)
 create mode 100644 Documentation/libtracefs-dynevents.txt
 create mode 100644 src/tracefs-dynevents.c

-- 
2.31.1

[PATCH v4 01/10] libtracefs: New APIs for dynamic events

[Tzvetomir Stoyanov (VMware)]

Ftrace supports dynamic events, created by the user - kprobes, uprobes,
eprobes and synthetic events. There are two interfaces for managing
these events - new common "dynamic_events" file and event specific
"kprobe_events", "uprobe_events", "synthetic_events" files. The
configuration syntax for all dynamic events is almost the same.
To simplify support of dynamic events in the tracefs library, new
APIs are introduced. They handle both configuration interfaces -
the common "dynamic_events" file is preferred, if available.
On the old kernels, where this file is missing, the event
specific files are used. The new APIs can be used to create,
delete and get ftrace dynamic events from any type:

 enum tracefs_dynevent_type;
 tracefs_dynevent_create();
 tracefs_dynevent_destroy();
 tracefs_dynevent_destroy_all();
 tracefs_dynevent_free();
 tracefs_dynevent_list_free();
 tracefs_dynevent_get_all();

There is no public API for allocation of a new dynamic event, as that
logic is specific for each dynamic event type.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/tracefs-local.h |  18 ++
 include/tracefs.h       |  19 ++
 src/Makefile            |   1 +
 src/tracefs-dynevents.c | 689 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 727 insertions(+)
 create mode 100644 src/tracefs-dynevents.c

diff --git a/include/tracefs-local.h b/include/tracefs-local.h
index 684eccf..f1a532c 100644
--- a/include/tracefs-local.h
+++ b/include/tracefs-local.h
@@ -94,4 +94,22 @@ int synth_add_start_field(struct tracefs_synth *synth,
 			  const char *start_field,
 			  const char *name,
 			  enum tracefs_hist_key_type type);
+
+/* Internal interface for ftrace dynamic events */
+
+struct tracefs_dynevent {
+	char *trace_file;
+	char *prefix;
+	char *system;
+	char *event;
+	char *address;
+	char *format;
+	enum tracefs_dynevent_type type;
+};
+
+struct tracefs_dynevent *
+dynevent_alloc(enum tracefs_dynevent_type type, const char *system,
+	       const char *event, const char *address, const char *format);
+int dynevent_get_count(enum tracefs_dynevent_type types, const char *system);
+
 #endif /* _TRACE_FS_LOCAL_H */
diff --git a/include/tracefs.h b/include/tracefs.h
index a2cda30..81f22af 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -238,6 +238,25 @@ ssize_t tracefs_trace_pipe_stream(int fd, struct tracefs_instance *instance, int
 ssize_t tracefs_trace_pipe_print(struct tracefs_instance *instance, int flags);
 void tracefs_trace_pipe_stop(struct tracefs_instance *instance);
 
+/* Dynamic events */
+struct tracefs_dynevent;
+enum tracefs_dynevent_type {
+	TRACEFS_DYNEVENT_KPROBE		= 1 << 0,
+	TRACEFS_DYNEVENT_KRETPROBE	= 1 << 1,
+	TRACEFS_DYNEVENT_UPROBE		= 1 << 2,
+	TRACEFS_DYNEVENT_URETPROBE	= 1 << 3,
+	TRACEFS_DYNEVENT_EPROBE		= 1 << 4,
+	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(enum tracefs_dynevent_type types, bool force);
+void tracefs_dynevent_free(struct tracefs_dynevent *devent);
+void tracefs_dynevent_list_free(struct tracefs_dynevent **events);
+struct tracefs_dynevent **
+tracefs_dynevent_get_all(enum tracefs_dynevent_type types, const char *system);
+
 enum tracefs_kprobe_type {
 	TRACEFS_ALL_KPROBES,
 	TRACEFS_KPROBE,
diff --git a/src/Makefile b/src/Makefile
index 4e38d98..99cd7da 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -11,6 +11,7 @@ OBJS += tracefs-marker.o
 OBJS += tracefs-kprobes.o
 OBJS += tracefs-hist.o
 OBJS += tracefs-filter.o
+OBJS += tracefs-dynevents.o
 
 # Order matters for the the three below
 OBJS += sqlhist-lex.o
diff --git a/src/tracefs-dynevents.c b/src/tracefs-dynevents.c
new file mode 100644
index 0000000..0437629
--- /dev/null
+++ b/src/tracefs-dynevents.c
@@ -0,0 +1,689 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ * Copyright (C) 2021 VMware Inc, Steven Rostedt <rostedt@goodmis.org>
+ *
+ * Updates:
+ * Copyright (C) 2021, VMware, Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
+ *
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+
+#include "tracefs.h"
+#include "tracefs-local.h"
+
+#define DYNEVENTS_EVENTS "dynamic_events"
+#define KPROBE_EVENTS "kprobe_events"
+#define UPROBE_EVENTS "uprobe_events"
+#define SYNTH_EVENTS "synthetic_events"
+#define DYNEVENTS_DEFAULT_GROUP "dynamic"
+
+struct dyn_events_desc;
+static int dyn_generic_parse(struct dyn_events_desc *,
+			     const char *, char *, struct tracefs_dynevent **);
+static int dyn_synth_parse(struct dyn_events_desc *,
+			   const char *, char *, struct tracefs_dynevent **);
+static int dyn_generic_del(struct dyn_events_desc *, struct tracefs_dynevent *);
+static int dyn_synth_del(struct dyn_events_desc *, struct tracefs_dynevent *);
+
+struct dyn_events_desc {
+	enum tracefs_dynevent_type type;
+	const char *file;
+	const char *prefix;
+	int (*del)(struct dyn_events_desc *desc, struct tracefs_dynevent *dyn);
+	int (*parse)(struct dyn_events_desc *desc, const char *group,
+				char *line, struct tracefs_dynevent **ret_dyn);
+} dynevents[] = {
+	{TRACEFS_DYNEVENT_KPROBE, NULL, "p", dyn_generic_del, dyn_generic_parse},
+	{TRACEFS_DYNEVENT_KRETPROBE, NULL, "r", dyn_generic_del, dyn_generic_parse},
+	{TRACEFS_DYNEVENT_UPROBE, NULL, "p", dyn_generic_del, dyn_generic_parse},
+	{TRACEFS_DYNEVENT_URETPROBE, NULL, "r", dyn_generic_del, dyn_generic_parse},
+	{TRACEFS_DYNEVENT_EPROBE, NULL, "e", dyn_generic_del, dyn_generic_parse},
+	{TRACEFS_DYNEVENT_SYNTH, NULL, "s", dyn_synth_del, dyn_synth_parse},
+};
+
+/* get position of the first set bit */
+static inline int bit_index(unsigned int bits)
+{
+	int i = 0;
+
+	while (bits) {
+		if (bits & 0x1)
+			return i;
+		bits >>= 1;
+		i++;
+	}
+
+	return -1;
+}
+
+static int dyn_generic_del(struct dyn_events_desc *desc, struct tracefs_dynevent *dyn)
+{
+	char *str;
+	int ret;
+
+	if (dyn->system)
+		ret = asprintf(&str, "-:%s/%s", dyn->system, dyn->event);
+	else
+		ret = asprintf(&str, "-:%s", dyn->event);
+
+	if (ret < 0)
+		return -1;
+
+	ret = tracefs_instance_file_append(NULL, desc->file, str);
+	free(str);
+
+	return ret < 0 ? ret : 0;
+}
+
+/**
+ * tracefs_dynevent_free - Free a dynamic event context
+ * @devent: Pointer to a dynamic event context
+ *
+ * The dynamic event, described by this context, is not
+ * removed from the system by this API. It only frees the memory.
+ */
+void tracefs_dynevent_free(struct tracefs_dynevent *devent)
+{
+	if (!devent)
+		return;
+	free(devent->system);
+	free(devent->event);
+	free(devent->address);
+	free(devent->format);
+	free(devent->prefix);
+	free(devent->trace_file);
+	free(devent);
+}
+
+static void parse_prefix(char *word, char **prefix, char **system, char **name)
+{
+	char *sav;
+
+	*prefix = NULL;
+	*system = NULL;
+	*name = NULL;
+
+	*prefix = strtok_r(word, ":", &sav);
+	*system = strtok_r(NULL, "/", &sav);
+	if (!(*system))
+		return;
+
+	*name = strtok_r(NULL, " ", &sav);
+	if (!(*name)) {
+		*name = *system;
+		*system = NULL;
+	}
+}
+
+/*
+ * Parse lines from dynamic_events, kprobe_events and uprobe_events files
+ * PREFIX[:[SYSTEM/]EVENT] [ADDRSS] [FORMAT]
+ */
+static int dyn_generic_parse(struct dyn_events_desc *desc, const char *group,
+			     char *line, struct tracefs_dynevent **ret_dyn)
+{
+	struct tracefs_dynevent *dyn;
+	char *word;
+	char *format = NULL;
+	char *address;
+	char *system;
+	char *prefix;
+	char *event;
+	char *sav;
+
+	if (strncmp(line, desc->prefix, strlen(desc->prefix)))
+		return -1;
+
+	word = strtok_r(line, " ", &sav);
+	if (!word || *word == '\0')
+		return -1;
+
+	parse_prefix(word, &prefix, &system, &event);
+	if (!prefix)
+		return -1;
+
+	if (desc->type != TRACEFS_DYNEVENT_SYNTH) {
+		address = strtok_r(NULL, " ", &sav);
+		if (!address || *address == '\0')
+			return -1;
+	}
+
+	format = strtok_r(NULL, "", &sav);
+
+	/* KPROBEs and UPROBEs share the same prefix, check the format */
+	if (desc->type == TRACEFS_DYNEVENT_UPROBE || desc->type == TRACEFS_DYNEVENT_URETPROBE) {
+		if (!strchr(address, '/'))
+			return -1;
+	}
+
+	if (group && (!system || strcmp(group, system) != 0))
+		return -1;
+
+	if (!ret_dyn)
+		return 0;
+
+	dyn = calloc(1, sizeof(*dyn));
+	if (!dyn)
+		return -1;
+
+	dyn->type = desc->type;
+	dyn->trace_file = strdup(desc->file);
+	if (!dyn->trace_file)
+		goto error;
+
+	dyn->prefix = strdup(prefix);
+	if (!dyn->prefix)
+		goto error;
+
+	if (system) {
+		dyn->system = strdup(system);
+		if (!dyn->system)
+			goto error;
+	}
+
+	if (event) {
+		dyn->event = strdup(event);
+		if (!dyn->event)
+			goto error;
+	}
+
+	if (address) {
+		dyn->address = strdup(address);
+		if (!dyn->address)
+			goto error;
+
+	}
+
+	if (format) {
+		dyn->format = strdup(format);
+		if (!dyn->format)
+			goto error;
+
+	}
+
+	*ret_dyn = dyn;
+	return 0;
+error:
+	tracefs_dynevent_free(dyn);
+	return -1;
+}
+
+static int dyn_synth_del(struct dyn_events_desc *desc, struct tracefs_dynevent *dyn)
+{
+	char *str;
+	int ret;
+
+	if (strcmp(desc->file, DYNEVENTS_EVENTS))
+		return dyn_generic_del(desc, dyn);
+
+	ret = asprintf(&str, "!%s", dyn->event);
+	if (ret < 0)
+		return -1;
+
+	ret = tracefs_instance_file_append(NULL, desc->file, str);
+	free(str);
+
+	return ret < 0 ? ret : 0;
+}
+
+/*
+ * Parse lines from synthetic_events file
+ * EVENT ARG [ARG]
+ */
+static int dyn_synth_parse(struct dyn_events_desc *desc, const char *group,
+			   char *line, struct tracefs_dynevent **ret_dyn)
+{
+	struct tracefs_dynevent *dyn;
+	char *format;
+	char *event;
+	char *sav;
+
+	if (strcmp(desc->file, DYNEVENTS_EVENTS))
+		return dyn_generic_parse(desc, group, line, ret_dyn);
+
+	/* synthetic_events file has slightly different syntax */
+	event = strtok_r(line, " ", &sav);
+	if (!event || *event == '\0')
+		return -1;
+
+	format = strtok_r(NULL, "", &sav);
+	if (!format || *format == '\0')
+		return -1;
+
+	if (!ret_dyn)
+		return 0;
+
+	dyn = calloc(1, sizeof(*dyn));
+	if (!dyn)
+		return -1;
+
+	dyn->type = desc->type;
+	dyn->trace_file = strdup(desc->file);
+	if (!dyn->trace_file)
+		goto error;
+
+	dyn->event = strdup(event);
+	if (!dyn->event)
+		goto error;
+
+	dyn->format = strdup(format+1);
+	if (!dyn->format)
+		goto error;
+
+	*ret_dyn = dyn;
+	return 0;
+error:
+	tracefs_dynevent_free(dyn);
+	return -1;
+}
+
+static void init_devent_desc(void)
+{
+	int max = bit_index(TRACEFS_DYNEVENT_MAX);
+	int i;
+
+	BUILD_BUG_ON(ARRAY_SIZE(dynevents) != max);
+
+	/* Use  ftrace dynamic_events, if available */
+	if (tracefs_file_exists(NULL, DYNEVENTS_EVENTS)) {
+		for (i = 0; i < max; i++)
+			dynevents[i].file = DYNEVENTS_EVENTS;
+		return;
+	}
+
+	if (tracefs_file_exists(NULL, KPROBE_EVENTS)) {
+		dynevents[bit_index(TRACEFS_DYNEVENT_KPROBE)].file = KPROBE_EVENTS;
+		dynevents[bit_index(TRACEFS_DYNEVENT_KRETPROBE)].file = KPROBE_EVENTS;
+	}
+	if (tracefs_file_exists(NULL, UPROBE_EVENTS)) {
+		dynevents[bit_index(TRACEFS_DYNEVENT_UPROBE)].file = UPROBE_EVENTS;
+		dynevents[bit_index(TRACEFS_DYNEVENT_URETPROBE)].file = UPROBE_EVENTS;
+	}
+	if (tracefs_file_exists(NULL, SYNTH_EVENTS)) {
+		dynevents[bit_index(TRACEFS_DYNEVENT_SYNTH)].file = SYNTH_EVENTS;
+		dynevents[bit_index(TRACEFS_DYNEVENT_SYNTH)].prefix = "";
+	}
+
+}
+
+static struct dyn_events_desc *get_devent_desc(int index)
+{
+	static bool init;
+	static int max;
+
+	if (index < 0)
+		return NULL;
+
+	if (!init) {
+		init_devent_desc();
+		max = bit_index(TRACEFS_DYNEVENT_MAX);
+		init = true;
+	}
+
+	if (index < 0 || index >= max)
+		return NULL;
+
+	return &dynevents[index];
+}
+
+/**
+ * dynevent_alloc - Allocate new dynamic event
+ * @type: Type of the dynamic event
+ * @system: The system name (NULL for the default dynamic)
+ * @event: Name of the event
+ * @addr: The function and offset (or address) to insert the probe
+ * @format: The format string to define the probe.
+ *
+ * Allocate a dynamic event context that will be in the @system group
+ * (or dynamic if @system is NULL). Have the name of @event and
+ * will be associated to @addr, if applicable for that event type
+ * (function name, with or without offset, or a address). And the @format will
+ * define the format of the kprobe.
+ * The dynamic event is not created in the system.
+ *
+ * Return a pointer to a dynamic event context on success, or NULL on error.
+ * The returned pointer must be freed with tracefs_dynevent_free()
+ *
+ * errno will be set to EINVAL if event is NULL.
+ */
+__hidden struct tracefs_dynevent *
+dynevent_alloc(enum tracefs_dynevent_type type, const char *system,
+	       const char *event, const char *address, const char *format)
+{
+	struct tracefs_dynevent *devent;
+	struct dyn_events_desc *desc;
+
+	if (!event) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	desc = get_devent_desc(bit_index(type));
+	if (!desc || !desc->file) {
+		errno = ENOTSUP;
+		return NULL;
+	}
+
+	devent = calloc(1, sizeof(*devent));
+	if (!devent)
+		return NULL;
+
+	devent->type = type;
+	devent->trace_file = strdup(desc->file);
+	if (!devent->trace_file)
+		goto err;
+
+	if (!system)
+		system = DYNEVENTS_DEFAULT_GROUP;
+	devent->system = strdup(system);
+	if (!devent->system)
+		goto err;
+
+	devent->event = strdup(event);
+	if (!devent->event)
+		goto err;
+
+	devent->prefix = strdup(desc->prefix);
+	if (!devent->prefix)
+		goto err;
+
+	if (address) {
+		devent->address = strdup(address);
+		if (!devent->address)
+			goto err;
+	}
+	if (format) {
+		devent->format = strdup(format);
+		if (!devent->format)
+			goto err;
+	}
+
+	return devent;
+err:
+	tracefs_dynevent_free(devent);
+	return NULL;
+}
+
+/**
+ * tracefs_dynevent_create - Create a dynamic event in the system
+ * @devent: Pointer to a dynamic event context, describing the event
+ *
+ * Return 0 on success, or -1 on error.
+ */
+int tracefs_dynevent_create(struct tracefs_dynevent *devent)
+{
+	char *str;
+	int ret;
+
+	if (!devent)
+		return -1;
+
+	if (devent->system && devent->system[0])
+		ret = asprintf(&str, "%s%s%s/%s %s %s\n",
+				devent->prefix, strlen(devent->prefix) ? ":" : "",
+				devent->system, devent->event,
+				devent->address ? devent->address : "",
+				devent->format ? devent->format : "");
+	else
+		ret = asprintf(&str, "%s%s%s %s %s\n",
+				devent->prefix, strlen(devent->prefix) ? ":" : "",
+				devent->event,
+				devent->address ? devent->address : "",
+				devent->format ? devent->format : "");
+	if (ret < 0)
+		return -1;
+
+	ret = tracefs_instance_file_append(NULL, devent->trace_file, str);
+	free(str);
+
+	return ret < 0 ? ret : 0;
+}
+
+static void disable_events(const char *system, const char *event,
+			   char **list)
+{
+	struct tracefs_instance *instance;
+	int i;
+
+	/*
+	 * Note, this will not fail even on error.
+	 * That is because even if something fails, it may still
+	 * work enough to clear the kprobes. If that's the case
+	 * the clearing after the loop will succeed and the function
+	 * is a success, even though other parts had failed. If
+	 * one of the kprobe events is enabled in one of the
+	 * instances that fail, then the clearing will fail too
+	 * and the function will return an error.
+	 */
+
+	tracefs_event_disable(NULL, system, event);
+	/* No need to test results */
+
+	if (!list)
+		return;
+
+	for (i = 0; list[i]; i++) {
+		instance = tracefs_instance_alloc(NULL, list[i]);
+		/* If this fails, try the next one */
+		if (!instance)
+			continue;
+		tracefs_event_disable(instance, system, event);
+		tracefs_instance_free(instance);
+	}
+}
+
+/**
+ * tracefs_dynevent_destroy - Remove a dynamic event from the system
+ * @devent: A dynamic event context, describing the dynamic event that will be deleted.
+ * @force: Will attempt to disable all events before removing them.
+ *
+ * The dynamic event context is not freed by this API. It only removes the event from the system.
+ * If there are any enabled events, and @force is not set, then it will error with -1 and errno
+ * to be EBUSY.
+ *
+ * Return 0 on success, or -1 on error.
+ */
+int tracefs_dynevent_destroy(struct tracefs_dynevent *devent, bool force)
+{
+	struct dyn_events_desc *desc;
+	char **instance_list;
+
+	if (!devent)
+		return -1;
+
+	if (force) {
+		instance_list = tracefs_instances(NULL);
+		disable_events(devent->system, devent->event, instance_list);
+		tracefs_list_free(instance_list);
+	}
+
+	desc = get_devent_desc(bit_index(devent->type));
+	if (!desc)
+		return -1;
+
+	return desc->del(desc, devent);
+}
+
+static int get_all_dynevents(int index, const char *system,
+			     struct tracefs_dynevent ***ret_all)
+{
+	struct dyn_events_desc *desc;
+	struct tracefs_dynevent *devent, **tmp, **all = NULL;
+	char *content;
+	int count = 0;
+	char *line;
+	char *next;
+	int ret;
+
+	desc = get_devent_desc(index);
+	if (!desc)
+		return -1;
+
+	content = tracefs_instance_file_read(NULL, desc->file, NULL);
+	if (!content)
+		return -1;
+
+	line = content;
+	do {
+		next = strchr(line, '\n');
+		if (next)
+			*next = '\0';
+		ret = desc->parse(desc, system, line, ret_all ? &devent : NULL);
+		if (!ret) {
+			if (ret_all) {
+				tmp = realloc(all, (count + 1) * sizeof(*tmp));
+				if (!tmp)
+					goto error;
+				all = tmp;
+				all[count] = devent;
+			}
+			count++;
+		}
+		line = next + 1;
+	} while (next);
+
+	free(content);
+	if (ret_all)
+		*ret_all = all;
+	return count;
+
+error:
+	free(content);
+	free(all);
+	return -1;
+}
+
+/**
+ * tracefs_dynevent_list_free - Deletes an array of pointers to dynamic event contexts
+ * @events: An array of pointers to dynamic event contexts. The last element of the array
+ *	    must be a NULL pointer.
+ */
+void tracefs_dynevent_list_free(struct tracefs_dynevent **events)
+{
+	int i = 0;
+
+	if (!events)
+		return;
+
+	while (events[i])
+		tracefs_dynevent_free(events[i++]);
+
+	free(events);
+}
+
+/**
+ * tracefs_dynevent_get_all - return an array of pointers to dynamic events of given types
+ * @types: Dynamic event type, or bitmask of dynamic event types. If 0 is passed, all types
+ *	   are considered.
+ * @system: Get events from that system only. If @system is NULL, events from all systems
+ *	    are returned.
+ *
+ * Returns an array of pointers to dynamic events of given types that exist in the system.
+ * The array must be freed with tracefs_dynevent_list_free(). If there are no events a NULL
+ * pointer is returned.
+ */
+struct tracefs_dynevent **
+tracefs_dynevent_get_all(enum tracefs_dynevent_type types, const char *system)
+{
+	struct tracefs_dynevent **events, **tmp, **all_events = NULL;
+	int count, all = 0;
+	int i;
+
+	for (i = 1; i < TRACEFS_DYNEVENT_MAX; i <<= 1) {
+		if (types) {
+			if (i > types)
+				break;
+			if (!(types & i))
+				continue;
+		}
+		count = get_all_dynevents(i - 1, system, &events);
+		if (count > 0) {
+			tmp = realloc(all_events, (all + count + 1) * sizeof(*tmp));
+			if (!tmp)
+				goto error;
+			all_events = tmp;
+			memcpy(all_events + all, events, count * sizeof(*events));
+			all += count;
+			/* Add a NULL pointer at the end */
+			all_events[all] = NULL;
+		}
+	}
+
+	return all_events;
+
+error:
+	if (all_events) {
+		for (i = 0; i < all; i++)
+			free(all_events[i]);
+		free(all_events);
+	}
+	return NULL;
+}
+
+/**
+ * tracefs_dynevent_destroy_all - removes all dynamic events of given types from the system
+ * @types: Dynamic event type, or bitmask of dynamic event types. If 0 is passed, all types
+ *	   are considered.
+ * @force: Will attempt to disable all events before removing them.
+ *
+ * Will remove all dynamic events of the given types from the system. If there are any enabled
+ * events, and @force is not set, then the removal of these will fail. If @force is set, then
+ * it will attempt to disable all the events in all instances before removing them.
+ *
+ * Returns zero if all requested events are removed successfully, or -1 if some of them are not
+ * removed.
+ */
+int tracefs_dynevent_destroy_all(enum tracefs_dynevent_type types, bool force)
+{
+	struct tracefs_dynevent **all;
+	int ret = 0;
+	int i;
+
+	all = tracefs_dynevent_get_all(types, NULL);
+	if (!all)
+		return 0;
+
+	for (i = 0; all[i]; i++) {
+		if (tracefs_dynevent_destroy(all[i], force))
+			ret = -1;
+	}
+
+	tracefs_dynevent_list_free(all);
+
+	return ret;
+}
+
+/**
+ * dynevent_get_count - Count dynamic events of given types and system
+ * @types: Dynamic event type, or bitmask of dynamic event types. If 0 is passed, all types
+ *	   are considered.
+ * @system: Count events from that system only. If @system is NULL, events from all systems
+ *	    are counted.
+ *
+ * Return the count of requested dynamic events
+ */
+__hidden int dynevent_get_count(enum tracefs_dynevent_type types, const char *system)
+{
+	int count, all = 0;
+	int i;
+
+	for (i = 1; i < TRACEFS_DYNEVENT_MAX; i <<= 1) {
+		if (types) {
+			if (i > types)
+				break;
+			if (!(types & i))
+				continue;
+		}
+		count = get_all_dynevents(i - 1, system, NULL);
+		if (count > 0)
+			all += count;
+	}
+
+	return all;
+}
-- 
2.31.1

[PATCH v4 02/10] libtracefs: New APIs for kprobe allocation

[Tzvetomir Stoyanov (VMware)]

In order to be consistent with the other APIs, new APIs for kprobe
allocation are introduced:
 tracefs_kprobe_alloc();
 tracefs_kretprobe_alloc();
These APIs allocate new kpobe dynamic event, that can be used with
tracefs_dynevent_... set of APIs.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/tracefs.h     |   5 ++
 src/tracefs-kprobes.c | 109 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 114 insertions(+)

diff --git a/include/tracefs.h b/include/tracefs.h
index 81f22af..3b2fc50 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -263,6 +263,11 @@ enum tracefs_kprobe_type {
 	TRACEFS_KRETPROBE,
 };
 
+struct tracefs_dynevent *
+tracefs_kprobe_alloc(const char *system, const char *event, const char *addr, const char *format);
+struct tracefs_dynevent *
+tracefs_kretprobe_alloc(const char *system, const char *event,
+			const char *addr, const char *format, int max);
 int tracefs_kprobe_raw(const char *system, const char *event,
 		       const char *addr, const char *format);
 int tracefs_kretprobe_raw(const char *system, const char *event,
diff --git a/src/tracefs-kprobes.c b/src/tracefs-kprobes.c
index 6fdd8f9..b2dcb0e 100644
--- a/src/tracefs-kprobes.c
+++ b/src/tracefs-kprobes.c
@@ -20,6 +20,115 @@
 #define KPROBE_EVENTS "kprobe_events"
 #define KPROBE_DEFAULT_GROUP "kprobes"
 
+static struct tracefs_dynevent *
+kprobe_alloc(enum tracefs_dynevent_type type, const char *system, const char *event,
+	     const char *addr, const char *format)
+{
+	struct tracefs_dynevent *kp;
+	const char *sys = system;
+	const char *ename = event;
+	char *tmp;
+
+	if (!addr) {
+		errno = EBADMSG;
+		return NULL;
+	}
+	if (!sys)
+		sys = KPROBE_DEFAULT_GROUP;
+
+	if (!event) {
+		ename = strdup(addr);
+		if (!ename)
+			return NULL;
+		tmp = strchr(ename, ':');
+		if (tmp)
+			*tmp = '\0';
+	}
+
+	kp = dynevent_alloc(type, sys, ename, addr, format);
+	if (!event)
+		free((char *)ename);
+
+	return kp;
+}
+
+/**
+ * tracefs_kprobe_alloc - Allocate new kprobe
+ * @system: The system name (NULL for the default kprobes)
+ * @event: The event to create (NULL to use @addr for the event)
+ * @addr: The function and offset (or address) to insert the probe
+ * @format: The format string to define the probe.
+ *
+ * Allocate a kprobe context that will be in the @system group (or kprobes if
+ * @system is NULL). Have the name of @event (or @addr if @event is NULL). Will
+ * be inserted to @addr (function name, with or without offset, or a address).
+ * And the @format will define the format of the kprobe.
+ *
+ * See the Linux documentation file under:
+ *  Documentation/trace/kprobetrace.rst
+ *
+ * The kprobe is not created in the system.
+ *
+ * Return a pointer to a kprobe context on success, or NULL on error.
+ * The returned pointer must be freed with tracefs_dynevent_free()
+ *
+ * errno will be set to EBADMSG if addr is NULL.
+ */
+struct tracefs_dynevent *
+tracefs_kprobe_alloc(const char *system, const char *event, const char *addr, const char *format)
+
+{
+	return kprobe_alloc(TRACEFS_DYNEVENT_KPROBE, system, event, addr, format);
+}
+
+/**
+ * tracefs_kretprobe_alloc - Allocate new kretprobe
+ * @system: The system name (NULL for the default kprobes)
+ * @event: The event to create (NULL to use @addr for the event)
+ * @addr: The function and offset (or address) to insert the retprobe
+ * @format: The format string to define the retprobe.
+ * @max: Maximum number of instances of the specified function that
+ *	 can be probed simultaneously, or 0 for the default value.
+ *
+ * Allocate a kretprobe that will be in the @system group (or kprobes if
+ * @system is NULL). Have the name of @event (or @addr if @event is
+ * NULL). Will be inserted to @addr (function name, with or without
+ * offset, or a address). And the @format will define the raw format
+ * of the kprobe. See the Linux documentation file under:
+ * Documentation/trace/kprobetrace.rst
+ * The kretprobe is not created in the system.
+ *
+ * Return a pointer to a kprobe context on success, or NULL on error.
+ * The returned pointer must be freed with tracefs_dynevent_free()
+ *
+ * errno will be set to EBADMSG if addr is NULL.
+ */
+struct tracefs_dynevent *
+tracefs_kretprobe_alloc(const char *system, const char *event,
+			const char *addr, const char *format, int max)
+{
+	struct tracefs_dynevent *kp;
+	int ret;
+
+	kp = kprobe_alloc(TRACEFS_DYNEVENT_KRETPROBE, system, event, addr, format);
+	if (!kp)
+		return NULL;
+
+	if (!max)
+		return kp;
+
+	free(kp->prefix);
+	kp->prefix = NULL;
+	ret = asprintf(&kp->prefix, "r%d:", max);
+	if (ret < 0)
+		goto error;
+
+	return kp;
+error:
+	tracefs_dynevent_free(kp);
+	return NULL;
+}
+
 static int insert_kprobe(const char *type, const char *system,
 			 const char *event, const char *addr,
 			 const char *format)
-- 
2.31.1

[PATCH v4 03/10] libtracefs: Remove redundant kprobes APIs

[Tzvetomir Stoyanov (VMware)]

The newly introduced set of APIs tracefs_dynevent_...() can be used to
manage kprobes. These legacy APIs are removed as redundant:
 tracefs_kprobe_clear_all();
 tracefs_kprobe_clear_probe();
 tracefs_get_kprobes()

There is one functionality, missing in the new clear API - clearing all
dynamic events from specific system only. If this is needed,
tracefs_dynevent_destroy() can be extended with that use case.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/tracefs.h     |   3 -
 src/tracefs-kprobes.c | 247 ------------------------------------------
 2 files changed, 250 deletions(-)

diff --git a/include/tracefs.h b/include/tracefs.h
index 3b2fc50..7d9a9af 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -272,11 +272,8 @@ int tracefs_kprobe_raw(const char *system, const char *event,
 		       const char *addr, const char *format);
 int tracefs_kretprobe_raw(const char *system, const char *event,
 			  const char *addr, const char *format);
-char **tracefs_get_kprobes(enum tracefs_kprobe_type type);
 enum tracefs_kprobe_type tracefs_kprobe_info(const char *group, const char *event,
 					     char **type, char **addr, char **format);
-int tracefs_kprobe_clear_all(bool force);
-int tracefs_kprobe_clear_probe(const char *system, const char *event, bool force);
 
 enum tracefs_hist_key_type {
 	TRACEFS_HIST_KEY_NORMAL = 0,
diff --git a/src/tracefs-kprobes.c b/src/tracefs-kprobes.c
index b2dcb0e..f67a93a 100644
--- a/src/tracefs-kprobes.c
+++ b/src/tracefs-kprobes.c
@@ -266,80 +266,6 @@ static int parse_kprobe(char *content, char **saveptr,
 	return 0;
 }
 
-/**
- * tracefs_get_kprobes - return a list kprobes (by group/event name)
- * @type: The type of kprobes to return.
- *
- * If @type is TRACEFS_ALL_KPROBES all kprobes in the kprobe_events
- * are returned. Otherwise if it is TRACEFS_KPROBE, then only
- * normal kprobes (p:) are returned, or if type is TRACEFS_KRETPROBE
- * then only kretprobes (r:) are returned.
- *
- * Returns a list of strings that contain the kprobes that exist
- * in the kprobe_events files. The strings returned are in the
- * "group/event" format.
- * The list must be freed with tracefs_list_free().
- * If there are no kprobes, a list is still returned, but it contains
- * only a NULL pointer.
- * On error, NULL is returned.
- */
-char **tracefs_get_kprobes(enum tracefs_kprobe_type type)
-{
-	char **list = NULL;
-	char *content;
-	char *saveptr;
-	char *event;
-	char *ktype;
-	int ret;
-
-	errno = 0;
-	content = tracefs_instance_file_read(NULL, KPROBE_EVENTS, NULL);
-	if (!content) {
-		if (errno)
-			return NULL;
-		/* content is NULL on empty file, return an empty list */
-		return trace_list_create_empty();
-	}
-
-	ret = parse_kprobe(content, &saveptr, &ktype, NULL, &event, NULL, NULL);
-
-	while (!ret) {
-		char **tmp;
-
-		if (type != TRACEFS_ALL_KPROBES) {
-			switch (*ktype) {
-			case 'p':
-				if (type != TRACEFS_KPROBE)
-					goto next;
-				break;
-			case 'r':
-				if (type != TRACEFS_KRETPROBE)
-					goto next;
-				break;
-			default:
-				goto next;
-			}
-		}
-
-		tmp = tracefs_list_add(list, event);
-		if (!tmp)
-			goto fail;
-		list = tmp;
- next:
-		ret = parse_kprobe(NULL, &saveptr, &ktype, NULL, &event, NULL, NULL);
-	}
-
-	if (!list)
-		list = trace_list_create_empty();
- out:
-	free(content);
-	return list;
- fail:
-	tracefs_list_free(list);
-	list = NULL;
-	goto out;
-}
-
 /**
  * tracefs_kprobe_info - return the type of kprobe specified.
  * @group: The group the kprobe is in (NULL for the default "kprobes")
@@ -410,176 +336,3 @@ enum tracefs_kprobe_type tracefs_kprobe_info(const char *group, const char *even
 	free(content);
 	return rtype;
 }
-
-static void disable_events(const char *system, const char *event,
-			   char **list)
-{
-	struct tracefs_instance *instance;
-	int i;
-
-	/*
-	 * Note, this will not fail even on error.
-	 * That is because even if something fails, it may still
-	 * work enough to clear the kprobes. If that's the case
-	 * the clearing after the loop will succeed and the function
-	 * is a success, even though other parts had failed. If
-	 * one of the kprobe events is enabled in one of the
-	 * instances that fail, then the clearing will fail too
-	 * and the function will return an error.
-	 */
-
-	tracefs_event_disable(NULL, system, event);
-	/* No need to test results */
-
-	if (!list)
-		return;
-
-	for (i = 0; list[i]; i++) {
-		instance = tracefs_instance_alloc(NULL, list[i]);
-		/* If this fails, try the next one */
-		if (!instance)
-			continue;
-		tracefs_event_disable(instance, system, event);
-		tracefs_instance_free(instance);
-	}
-	return;
-}
-
-static int clear_kprobe(const char *system, const char *event)
-{
-	/* '-' + ':' + '/' + '\n' + '\0' = 5 bytes */
-	int len = strlen(system) + strlen(event) + 5;
-	char content[len];
-
-	sprintf(content, "-:%s/%s", system, event);
-	return tracefs_instance_file_append(NULL, KPROBE_EVENTS, content);
-}
-
-static int kprobe_clear_probes(const char *group, bool force)
-{
-	char **instance_list;
-	char **kprobe_list;
-	char *saveptr;
-	char *system;
-	char *kprobe;
-	char *event;
-	int ret;
-	int i;
-
-	kprobe_list = tracefs_get_kprobes(TRACEFS_ALL_KPROBES);
-	if (!kprobe_list)
-		return -1;
-
-	instance_list = tracefs_instances(NULL);
-	/*
-	 * Even if the above failed and instance_list is NULL,
-	 * keep going, as the enabled event may simply be in the
-	 * top level.
-	 */
-
-	/*
-	 * If a system is defined, the default is to pass unless
-	 * an event fails to be removed. If a system is not defined,
-	 * the default is to fail, unless all are removed.
-	 */
-	ret = group ? 0 : -1;
-
-	for (i = 0; kprobe_list[i]; i++) {
-		kprobe = kprobe_list[i];
-
-		system = strtok_r(kprobe, "/", &saveptr);
-		if (!system)
-			goto out;
-
-		event = strtok_r(NULL," ", &saveptr);
-		if (!event)
-			goto out;
-
-		/* Skip if this does not match a given system */
-		if (group && strcmp(system, group) != 0)
-			continue;
-
-		if (force)
-			disable_events(system, event, instance_list);
-
-		if (group) {
-			ret = clear_kprobe(system, event);
-			if (ret < 0)
-				goto out;
-		} else {
-			ret = tracefs_instance_file_clear(NULL, KPROBE_EVENTS);
-			/* On success stop the loop */
-			if (!ret)
-				goto out;
-		}
-
-		/* Set the default for whether a system is defined or not */
-		ret = group ? 0 : -1;
-	}
- out:
-	tracefs_list_free(instance_list);
-	tracefs_list_free(kprobe_list);
-	return ret;
-}
-
-/**
- * tracefs_kprobe_clear_all - clear kprobe events
- * @force: Will attempt to disable all kprobe events and clear them
- *
- * Will remove all defined kprobe events. If any of them are enabled,
- * and @force is not set, then it will error with -1 and errno to be
- * EBUSY. If @force is set, then it will attempt to disable all the kprobe
- * events in all instances, and try again.
- *
- * Returns zero on success, -1 otherwise.
- */
-int tracefs_kprobe_clear_all(bool force)
-{
-	if (tracefs_instance_file_clear(NULL, KPROBE_EVENTS) == 0)
-		return 0;
-
-	if (!force)
-		return -1;
-
-	/* Attempt to disable all kprobe events */
-	return kprobe_clear_probes(NULL, force);
-}
-
-/**
- * tracefs_kprobe_clear_all - clear kprobe events
- * @system: System to clear (NULL means default)
- * @event: Name of probe to clear in system (NULL for all probes in system)
- * @force: Will attempt to disable all kprobe events and clear them
- *
- * Will remove the kprobes that match the @system and @event. If @system
- * is NULL, then "kprobes" is used and will ignore all other system
- * groups of kprobes. The @event is NULL then all events under the given
- * @system are removed, otherwise only the event that matches.
- *
- * Returns zero on success, -1 otherwise.
- */
-int tracefs_kprobe_clear_probe(const char *system, const char *event, bool force)
-{
-	char **instance_list;
-	int ret;
-
-	if (!system)
-		system = "kprobes";
-
-	if (!event)
-		return kprobe_clear_probes(system, force);
-
-	/*
-	 * Since we know we are disabling a specific event, try
-	 * to disable it first before clearing it.
-	 */
-	if (force) {
-		instance_list = tracefs_instances(NULL);
-		disable_events(system, event, instance_list);
-		tracefs_list_free(instance_list);
-	}
-
-	ret = clear_kprobe(system, event);
-
-	return ret < 0 ? -1 : 0;
-}
-- 
2.31.1

[PATCH v4 04/10] libtracefs: Change tracefs_kprobe_info API

[Tzvetomir Stoyanov (VMware)]

In order to make kprobe APIs consistent with the other libtracefs APIs,
the tracefs_kprobe_info() API is reimplemented and changed to work with
the library dynamic event structure.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/tracefs.h     |  11 +--
 src/tracefs-kprobes.c | 159 ++++++++++++------------------------------
 2 files changed, 48 insertions(+), 122 deletions(-)

diff --git a/include/tracefs.h b/include/tracefs.h
index 7d9a9af..8377ade 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -257,12 +257,6 @@ void tracefs_dynevent_list_free(struct tracefs_dynevent **events);
 struct tracefs_dynevent **
 tracefs_dynevent_get_all(enum tracefs_dynevent_type types, const char *system);
 
-enum tracefs_kprobe_type {
-	TRACEFS_ALL_KPROBES,
-	TRACEFS_KPROBE,
-	TRACEFS_KRETPROBE,
-};
-
 struct tracefs_dynevent *
 tracefs_kprobe_alloc(const char *system, const char *event, const char *addr, const char *format);
 struct tracefs_dynevent *
@@ -272,8 +266,9 @@ int tracefs_kprobe_raw(const char *system, const char *event,
 		       const char *addr, const char *format);
 int tracefs_kretprobe_raw(const char *system, const char *event,
 			  const char *addr, const char *format);
-enum tracefs_kprobe_type tracefs_kprobe_info(const char *group, const char *event,
-					     char **type, char **addr, char **format);
+enum tracefs_dynevent_type tracefs_kprobe_info(struct tracefs_dynevent *kprobe,
+					       char **system, char **event,
+					       char **prefix, char **addr, char **format);
 
 enum tracefs_hist_key_type {
 	TRACEFS_HIST_KEY_NORMAL = 0,
diff --git a/src/tracefs-kprobes.c b/src/tracefs-kprobes.c
index f67a93a..a391637 100644
--- a/src/tracefs-kprobes.c
+++ b/src/tracefs-kprobes.c
@@ -214,125 +214,56 @@ int tracefs_kretprobe_raw(const char *system, const char *event,
 	return insert_kprobe("r", system, event, addr, format);
 }
 
-/*
- * Helper function to parse kprobes.
- * @content: The content of kprobe_events on the first iteration.
- *           NULL on next iterations.
- * @saveptr: Same as saveptr for strtok_r
- * @type: Where to store the type (before ':')
- * @system: Store the system of the kprobe (NULL to have event contain
- *          both system and event, as in "kprobes/myprobe").
- * @event: Where to store the event.
- * @addr: Where to store the addr (may be NULL to ignore)
- * @format: Where to store the format (may be NULL to ignore)
- */
-static int parse_kprobe(char *content, char **saveptr,
-			char **type, char **system, char **event,
-			char **addr, char **format)
-{
-	char *p;
-
-	p = strtok_r(content, ":", saveptr);
-	if (!p)
-		return 1; /* eof */
-	*type = p;
-
-	if (system) {
-		p = strtok_r(NULL, "/", saveptr);
-		if (!p)
-			return -1;
-		*system = p;
-	}
-
-	p = strtok_r(NULL, " ", saveptr);
-	if (!p)
-		return -1;
-	*event = p;
-
-	if (addr || format) {
-		p = strtok_r(NULL, " ", saveptr);
-		if (!p)
-			return -1;
-		if (addr)
-			*addr = p;
-	}
-
-	p = strtok_r(NULL, "\n", saveptr);
-	if (!p)
-		return -1;
-	if (format)
-		*format = p;
-
-	return 0;
-}
-
 /**
- * tracefs_kprobe_info - return the type of kprobe specified.
- * @group: The group the kprobe is in (NULL for the default "kprobes")
- * @event: The name of the kprobe to find.
- * @type: String to return kprobe type (before ':') NULL to ignore.
- * @addr: String to return address kprobe is attached to. NULL to ignore.
- * @format: String to return kprobe format. NULL to ignore.
- *
- * If @type, @addr, or @format is non NULL, then the returned string
- * must be freed with free(). They will also be set to NULL, and
- * even on error, they may contain strings to be freed. If they are
- * not NULL, then they still need to be freed.
+ * tracefs_kprobe_info - return details of a kprobe
+ * @kprobe: A kprobe context, describing given kprobe.
+ * @group: return, group in which the kprobe is configured
+ * @event: return, name of the kprobe event
+ * @prefix: return, prefix string of the kprobe
+ *	    for kretprobes, the maxactive count is encoded in the prefix
+ * @addr: return, the function and offset (or address) of the kprobe
+ * @format: return, the format string of the kprobe
  *
- * Returns TRACEFS_ALL_KPROBES if an error occurs or the kprobe is not found,
- *            or the probe is of an unknown type.
- * TRACEFS_KPROBE if the type of kprobe found is a normal kprobe.
- * TRACEFS_KRETPROBE if the type of kprobe found is a kretprobe.
+ * Returns the type of the kprobe, or TRACEFS_DYNEVENT_MAX in case of an error.
+ * Any of the @group, @event, @prefix, @addr and @format parameters are optional.
+ * If a valid pointer is passed, in case of success - a string is allocated and returned.
+ * These strings must be freed with free().
  */
-enum tracefs_kprobe_type tracefs_kprobe_info(const char *group, const char *event,
-					     char **type, char **addr, char **format)
-{
-	enum tracefs_kprobe_type rtype = TRACEFS_ALL_KPROBES;
-	char *saveptr;
-	char *content;
-	char *system;
-	char *probe;
-	char *ktype;
-	char *kaddr;
-	char *kfmt;
-	int ret;
-
-	if (!group)
-		group = KPROBE_DEFAULT_GROUP;
-
-	if (type)
-		*type = NULL;
-	if (addr)
-		*addr = NULL;
-	if (format)
-		*format = NULL;
-
-	content = tracefs_instance_file_read(NULL, KPROBE_EVENTS, NULL);
-	if (!content)
-		return rtype;
-
-	ret = parse_kprobe(content, &saveptr, &ktype, &system, &probe,
-			   &kaddr, &kfmt);
-
-	while (!ret) {
-
-		if (!strcmp(system, group) && !strcmp(probe, event)) {
-			if (type)
-				*type = strdup(ktype);
-			if (addr)
-				*addr = strdup(kaddr);
-			if (format)
-				*format = strdup(kfmt);
 
-			switch (*ktype) {
-			case 'p': rtype = TRACEFS_KPROBE; break;
-			case 'r': rtype = TRACEFS_KRETPROBE; break;
+enum tracefs_dynevent_type tracefs_kprobe_info(struct tracefs_dynevent *kprobe,
+					       char **system, char **event,
+					       char **prefix, char **addr, char **format)
+{
+	char **lv[] = { system, event, prefix, addr, format };
+	char **rv[] = { &kprobe->system, &kprobe->event, &kprobe->prefix,
+			&kprobe->address, &kprobe->format };
+	int i;
+
+	if (!kprobe)
+		return TRACEFS_DYNEVENT_MAX;
+
+	for (i = 0; i < ARRAY_SIZE(lv); i++)
+		*lv[i] = NULL;
+
+	for (i = 0; i < ARRAY_SIZE(lv); i++) {
+		if (lv[i]) {
+			if (*rv[i]) {
+				*lv[i] = strdup(*rv[i]);
+				if (!*lv[i])
+					goto error;
+			} else {
+				*lv[i] = NULL;
 			}
-			break;
 		}
-		ret = parse_kprobe(NULL, &saveptr, &ktype, &system, &probe,
-				   &kaddr, &kfmt);
 	}
-	free(content);
-	return rtype;
+
+	return kprobe->type;
+
+error:
+	for (i--; i >= 0; i--) {
+		if (lv[i])
+			free(*lv[i]);
+	}
+
+	return TRACEFS_DYNEVENT_MAX;
 }
-- 
2.31.1

[PATCH v4 05/10] libtracefs: Reimplement kprobe raw APIs

[Tzvetomir Stoyanov (VMware)]

In order to unify the code and use the new dynamic event helpers, these
kprobe APIs are rewritten:
 kracefs_kprobe_raw()
 kracefs_kretprobe_raw()
The definition and logic of the APIs remain the same.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 src/tracefs-kprobes.c | 37 ++++++++++---------------------------
 1 file changed, 10 insertions(+), 27 deletions(-)

diff --git a/src/tracefs-kprobes.c b/src/tracefs-kprobes.c
index a391637..f152b67 100644
--- a/src/tracefs-kprobes.c
+++ b/src/tracefs-kprobes.c
@@ -129,37 +129,20 @@ error:
 	return NULL;
 }
 
-static int insert_kprobe(const char *type, const char *system,
-			 const char *event, const char *addr,
-			 const char *format)
+static int kprobe_raw(enum tracefs_dynevent_type type, const char *system,
+		      const char *event, const char *addr, const char *format)
 {
-	char *str;
+	static struct tracefs_dynevent *kp;
 	int ret;
 
-	if (!tracefs_file_exists(NULL, KPROBE_EVENTS))
-		return -1;
-
-	errno = EBADMSG;
-	if (!addr || !format)
-		return -1;
-
-	if (!event)
-		event = addr;
-
-	if (system)
-		ret = asprintf(&str, "%s:%s/%s %s %s\n",
-			       type, system, event, addr, format);
-	else
-		ret = asprintf(&str, "%s:%s %s %s\n",
-			       type, event, addr, format);
-
-	if (ret < 0)
+	kp = kprobe_alloc(type, system, event, addr, format);
+	if (!kp)
 		return -1;
 
-	ret = tracefs_instance_file_append(NULL, KPROBE_EVENTS, str);
-	free(str);
+	ret = tracefs_dynevent_create(kp);
+	tracefs_dynevent_free(kp);
 
-	return ret < 0 ? ret : 0;
+	return ret;
 }
 
 /**
@@ -185,7 +168,7 @@ static int insert_kprobe(const char *type, const char *system,
 int tracefs_kprobe_raw(const char *system, const char *event,
 		       const char *addr, const char *format)
 {
-	return insert_kprobe("p", system, event, addr, format);
+	return kprobe_raw(TRACEFS_DYNEVENT_KPROBE, system, event, addr, format);
 }
 
 /**
@@ -211,7 +194,7 @@ int tracefs_kprobe_raw(const char *system, const char *event,
 int tracefs_kretprobe_raw(const char *system, const char *event,
 			  const char *addr, const char *format)
 {
-	return insert_kprobe("r", system, event, addr, format);
+	return kprobe_raw(TRACEFS_DYNEVENT_KRETPROBE, system, event, addr, format);
 }
 
 /**
-- 
2.31.1

[PATCH v4 06/10] libtracefs: Extend kprobes unit test

[Tzvetomir Stoyanov (VMware)]

As there are a lot of changes in the libtracefs kprobes APIs, the unit
test of that functionality should be updated. A new test section is
added, for testing the all kprobes APIs.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 utest/tracefs-utest.c | 412 +++++++++++++++++++++++++-----------------
 1 file changed, 242 insertions(+), 170 deletions(-)

diff --git a/utest/tracefs-utest.c b/utest/tracefs-utest.c
index 09bb8f2..c590c6b 100644
--- a/utest/tracefs-utest.c
+++ b/utest/tracefs-utest.c
@@ -28,22 +28,6 @@
 #define TRACE_ON	"tracing_on"
 #define TRACE_CLOCK	"trace_clock"
 
-#define KPROBE_EVENTS	"kprobe_events"
-
-#define KPROBE_1_NAME	"mkdir"
-#define KPROBE_1_GROUP	"kprobes"
-#define KPROBE_1_ADDR	"do_mkdirat"
-#define KPROBE_1_FMT	"path=+u0($arg2):ustring"
-
-#define KPROBE_2_NAME	"open"
-#define KPROBE_2_GROUP	"myprobe"
-#define KPROBE_2_ADDR	"do_sys_openat2"
-#define KPROBE_2_FMT	"file=+u0($arg2):ustring flags=+0($arg3):x64"
-
-#define KRETPROBE_NAME	"retopen"
-#define KRETPROBE_ADDR	"do_sys_openat2"
-#define KRETPROBE_FMT	"ret=$retval"
-
 #define SQL_1_EVENT	"wakeup_1"
 #define SQL_1_SQL	"select sched_switch.next_pid as woke_pid, sched_waking.common_pid as waking_pid from sched_waking join sched_switch on sched_switch.next_pid = sched_waking.pid"
 
@@ -457,28 +441,262 @@ static void test_instance_file_read(struct tracefs_instance *inst, const char *f
 	free(file);
 }
 
+#define KPROBE_DEFAULT_GROUP "kprobes"
+struct kprobe_test {
+	enum tracefs_dynevent_type type;
+	char *prefix;
+	char *system;
+	char *event;
+	char *address;
+	char *format;
+};
+
+static bool check_kprobes(struct kprobe_test *kprobes, int count,
+			  struct tracefs_dynevent **devents, bool in_system)
+{
+
+	enum tracefs_dynevent_type ktype;
+	char *ename;
+	char *kaddress;
+	char *kevent;
+	char *ksystem;
+	char *kformat;
+	char *kprefix;
+	int found = 0;
+	int ret;
+	int i, j;
+
+	for (i = 0; devents && devents[i]; i++) {
+		ktype = tracefs_kprobe_info(devents[i], &ksystem,
+					   &kevent, &kprefix, &kaddress, &kformat);
+		for (j = 0; j < count; j++) {
+			if (ktype != kprobes[j].type)
+				continue;
+			if (kprobes[j].event)
+				ename = kprobes[j].event;
+			else
+				ename = kprobes[j].address;
+			if (strcmp(ename, kevent))
+				continue;
+			if (kprobes[j].system) {
+				CU_TEST(strcmp(kprobes[j].system, ksystem) == 0);
+			} else {
+				CU_TEST(strcmp(KPROBE_DEFAULT_GROUP, ksystem) == 0);
+			}
+			CU_TEST(strcmp(kprobes[j].address, kaddress) == 0);
+			if (kprobes[j].format) {
+				CU_TEST(strcmp(kprobes[j].format, kformat) == 0);
+			}
+			if (kprobes[j].prefix) {
+				CU_TEST(strcmp(kprobes[j].prefix, kprefix) == 0);
+			}
+			ret = tracefs_event_enable(test_instance, ksystem, kevent);
+			if (in_system) {
+				CU_TEST(ret == 0);
+			} else {
+				CU_TEST(ret != 0);
+			}
+			ret = tracefs_event_disable(test_instance, ksystem, kevent);
+			if (in_system) {
+				CU_TEST(ret == 0);
+			} else {
+				CU_TEST(ret != 0);
+			}
+
+			found++;
+			break;
+		}
+		free(ksystem);
+		free(kevent);
+		free(kprefix);
+		free(kaddress);
+		free(kformat);
+	}
+
+	CU_TEST(found == count);
+	if (found != count)
+		return false;
+
+	return true;
+}
+
+static struct tracefs_dynevent **get_kprobes_check(enum tracefs_dynevent_type types, int count)
+{
+	struct tracefs_dynevent **devents;
+	int i;
+
+	devents = tracefs_dynevent_get_all(types, NULL);
+	if (count) {
+		CU_TEST(devents != NULL);
+		if (!devents)
+			return NULL;
+		i = 0;
+		while (devents[i])
+			i++;
+		CU_TEST(i == count);
+	} else {
+		CU_TEST(devents == NULL);
+	}
+
+	return devents;
+}
+
+#define KPROBE_COUNT	3
+#define KRETPROBE_COUNT	2
+static void test_kprobes(void)
+{
+	struct kprobe_test ktests[KPROBE_COUNT] = {
+		{ TRACEFS_DYNEVENT_KPROBE, "p", NULL, "mkdir", "do_mkdirat", "path=+u0($arg2):ustring" },
+		{ TRACEFS_DYNEVENT_KPROBE, "p", NULL, "close", "close_fd", NULL },
+		{ TRACEFS_DYNEVENT_KPROBE, "p", "ptest", "open2", "do_sys_openat2",
+				  "file=+u0($arg2):ustring flags=+0($arg3):x64" },
+	};
+	struct kprobe_test kretests[KRETPROBE_COUNT] = {
+		{ TRACEFS_DYNEVENT_KRETPROBE, NULL, NULL, "retopen", "do_sys_openat2", "ret=$retval" },
+		{ TRACEFS_DYNEVENT_KRETPROBE, NULL, NULL, NULL, "do_sys_open", "ret=$retval" },
+	};
+	struct tracefs_dynevent *dkretprobe[KRETPROBE_COUNT + 1];
+	struct tracefs_dynevent *dkprobe[KPROBE_COUNT + 1];
+	struct tracefs_dynevent **devents;
+	char *tmp;
+	int ret;
+	int i;
+
+	/* Invalid parameters */
+	CU_TEST(tracefs_kprobe_alloc("test", NULL, NULL, "test") == NULL);
+	CU_TEST(tracefs_kretprobe_alloc("test", NULL, NULL, "test", 0) == NULL);
+	CU_TEST(tracefs_dynevent_create(NULL) != 0);
+	CU_TEST(tracefs_kprobe_info(NULL, &tmp, &tmp, &tmp, &tmp, &tmp) == TRACEFS_DYNEVENT_MAX);
+	CU_TEST(tracefs_kprobe_raw("test", "test", NULL, "test") != 0);
+	CU_TEST(tracefs_kretprobe_raw("test", "test", NULL, "test") != 0);
+
+	/* kprobes APIs */
+	ret = tracefs_dynevent_destroy_all(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE, true);
+	CU_TEST(ret == 0);
+	get_kprobes_check(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE, 0);
+
+	for (i = 0; i < KPROBE_COUNT; i++) {
+		dkprobe[i] = tracefs_kprobe_alloc(ktests[i].system, ktests[i].event,
+						  ktests[i].address, ktests[i].format);
+		CU_TEST(dkprobe[i] != NULL);
+	}
+	dkprobe[i] = NULL;
+	get_kprobes_check(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE, 0);
+	CU_TEST(check_kprobes(ktests, KPROBE_COUNT, dkprobe, false));
+
+	for (i = 0; i < KRETPROBE_COUNT; i++) {
+		dkretprobe[i] = tracefs_kretprobe_alloc(kretests[i].system, kretests[i].event,
+							kretests[i].address, kretests[i].format, 0);
+		CU_TEST(dkretprobe[i] != NULL);
+	}
+	dkretprobe[i] = NULL;
+	get_kprobes_check(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE, 0);
+	CU_TEST(check_kprobes(kretests, KRETPROBE_COUNT, dkretprobe, false));
+
+	for (i = 0; i < KPROBE_COUNT; i++) {
+		CU_TEST(tracefs_dynevent_create(dkprobe[i]) == 0);
+	}
+	devents = get_kprobes_check(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE,
+				    KPROBE_COUNT);
+	CU_TEST(check_kprobes(ktests, KPROBE_COUNT, devents, true));
+	CU_TEST(check_kprobes(kretests, KRETPROBE_COUNT, dkretprobe, false));
+	tracefs_dynevent_list_free(devents);
+	devents = NULL;
+
+	for (i = 0; i < KRETPROBE_COUNT; i++) {
+		CU_TEST(tracefs_dynevent_create(dkretprobe[i]) == 0);
+	}
+	devents = get_kprobes_check(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE,
+				    KPROBE_COUNT + KRETPROBE_COUNT);
+	CU_TEST(check_kprobes(ktests, KPROBE_COUNT, devents, true));
+	CU_TEST(check_kprobes(kretests, KRETPROBE_COUNT, devents, true));
+	tracefs_dynevent_list_free(devents);
+	devents = NULL;
+
+	for (i = 0; i < KRETPROBE_COUNT; i++) {
+		CU_TEST(tracefs_dynevent_destroy(dkretprobe[i], false) == 0);
+	}
+	devents = get_kprobes_check(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE,
+				    KPROBE_COUNT);
+	CU_TEST(check_kprobes(ktests, KPROBE_COUNT, devents, true));
+	CU_TEST(check_kprobes(kretests, KRETPROBE_COUNT, dkretprobe, false));
+	tracefs_dynevent_list_free(devents);
+	devents = NULL;
+
+	for (i = 0; i < KPROBE_COUNT; i++) {
+		CU_TEST(tracefs_dynevent_destroy(dkprobe[i], false) == 0);
+	}
+	get_kprobes_check(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE, 0);
+	CU_TEST(check_kprobes(ktests, KPROBE_COUNT, dkprobe, false));
+	CU_TEST(check_kprobes(kretests, KRETPROBE_COUNT, dkretprobe, false));
+	tracefs_dynevent_list_free(devents);
+	devents = NULL;
+
+	for (i = 0; i < KPROBE_COUNT; i++)
+		tracefs_dynevent_free(dkprobe[i]);
+	for (i = 0; i < KRETPROBE_COUNT; i++)
+		tracefs_dynevent_free(dkretprobe[i]);
+
+	/* kprobes raw APIs */
+	ret = tracefs_dynevent_destroy_all(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE, true);
+	CU_TEST(ret == 0);
+	get_kprobes_check(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE, 0);
+
+	for (i = 0; i < KPROBE_COUNT; i++) {
+		ret = tracefs_kprobe_raw(ktests[i].system, ktests[i].event,
+					 ktests[i].address, ktests[i].format);
+		CU_TEST(ret == 0);
+	}
+
+	devents = get_kprobes_check(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE, KPROBE_COUNT);
+	CU_TEST(check_kprobes(ktests, KPROBE_COUNT, devents, true));
+	tracefs_dynevent_list_free(devents);
+	devents = NULL;
+
+	for (i = 0; i < KRETPROBE_COUNT; i++) {
+		ret = tracefs_kretprobe_raw(kretests[i].system, kretests[i].event,
+					    kretests[i].address, kretests[i].format);
+		CU_TEST(ret == 0);
+	}
+
+	devents = get_kprobes_check(TRACEFS_DYNEVENT_KPROBE, KPROBE_COUNT);
+	CU_TEST(check_kprobes(ktests, KPROBE_COUNT, devents, true));
+	tracefs_dynevent_list_free(devents);
+	devents = NULL;
+
+	devents = get_kprobes_check(TRACEFS_DYNEVENT_KRETPROBE, KRETPROBE_COUNT);
+	CU_TEST(check_kprobes(kretests, KRETPROBE_COUNT, devents, true));
+	tracefs_dynevent_list_free(devents);
+	devents = NULL;
+
+	devents = get_kprobes_check(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE,
+				    KPROBE_COUNT + KRETPROBE_COUNT);
+	CU_TEST(check_kprobes(ktests, KPROBE_COUNT, devents, true));
+	CU_TEST(check_kprobes(kretests, KRETPROBE_COUNT, devents, true));
+	tracefs_dynevent_list_free(devents);
+	devents = NULL;
+
+	ret = tracefs_dynevent_destroy_all(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE, true);
+	CU_TEST(ret == 0);
+	get_kprobes_check(0, 0);
+}
+
 static void test_instance_file(void)
 {
 	struct tracefs_instance *instance = NULL;
 	struct tracefs_instance *second = NULL;
-	enum tracefs_kprobe_type type;
 	const char *name = get_rand_str();
 	const char *inst_name = NULL;
 	const char *tdir;
 	char *inst_file;
 	char *inst_dir;
 	struct stat st;
-	char **kprobes;
-	char *kformat;
-	char *ktype;
-	char *kaddr;
-	char *fname;
 	char *file1;
 	char *file2;
 	char *tracer;
+	char *fname;
 	int size;
 	int ret;
-	int i;
 
 	tdir  = tracefs_tracing_dir();
 	CU_TEST(tdir != NULL);
@@ -541,153 +759,6 @@ static void test_instance_file(void)
 	free(file1);
 	free(file2);
 
-	ret = tracefs_kprobe_clear_all(true);
-	CU_TEST(ret == 0);
-	ret = tracefs_kprobe_raw(NULL, KPROBE_1_NAME, KPROBE_1_ADDR, KPROBE_1_FMT);
-	CU_TEST(ret == 0);
-	ret = tracefs_kprobe_raw(KPROBE_2_GROUP, KPROBE_2_NAME, KPROBE_2_ADDR,
-				 KPROBE_2_FMT);
-	CU_TEST(ret == 0);
-
-	ret = tracefs_kretprobe_raw(KPROBE_2_GROUP, KRETPROBE_NAME, KRETPROBE_ADDR,
-				 KRETPROBE_FMT);
-	CU_TEST(ret == 0);
-
-	type = tracefs_kprobe_info(KPROBE_1_GROUP, KPROBE_1_NAME, &ktype,
-				   &kaddr, &kformat);
-	CU_TEST(type == TRACEFS_KPROBE);
-	CU_TEST(ktype && *ktype == 'p');
-	CU_TEST(kaddr && !strcmp(kaddr, KPROBE_1_ADDR));
-	CU_TEST(kformat && !strcmp(kformat, KPROBE_1_FMT));
-	free(ktype);
-	free(kaddr);
-	free(kformat);
-
-	type = tracefs_kprobe_info(KPROBE_2_GROUP, KPROBE_2_NAME, &ktype,
-				   &kaddr, &kformat);
-	CU_TEST(type == TRACEFS_KPROBE);
-	CU_TEST(ktype && *ktype == 'p');
-	CU_TEST(kaddr && !strcmp(kaddr, KPROBE_2_ADDR));
-	CU_TEST(kformat && !strcmp(kformat, KPROBE_2_FMT));
-	free(ktype);
-	free(kaddr);
-	free(kformat);
-
-	type = tracefs_kprobe_info(KPROBE_2_GROUP, KRETPROBE_NAME, &ktype,
-				   &kaddr, &kformat);
-	CU_TEST(type == TRACEFS_KRETPROBE);
-	CU_TEST(ktype && *ktype == 'r');
-	CU_TEST(kaddr && !strcmp(kaddr, KRETPROBE_ADDR));
-	CU_TEST(kformat && !strcmp(kformat, KRETPROBE_FMT));
-	free(ktype);
-	free(kaddr);
-	free(kformat);
-
-	kprobes = tracefs_get_kprobes(TRACEFS_ALL_KPROBES);
-	CU_TEST(kprobes != NULL);
-
-	for (i = 0; kprobes[i]; i++) {
-		char *system = strtok(kprobes[i], "/");
-		char *event = strtok(NULL, "");
-		bool found = false;
-		if (!strcmp(system, KPROBE_1_GROUP)) {
-			CU_TEST(!strcmp(event, KPROBE_1_NAME));
-			found = true;
-		} else if (!strcmp(system, KPROBE_2_GROUP)) {
-			switch (tracefs_kprobe_info(system, event, NULL, NULL, NULL)) {
-			case TRACEFS_KPROBE:
-				CU_TEST(!strcmp(event, KPROBE_2_NAME));
-				found = true;
-				break;
-			case TRACEFS_KRETPROBE:
-				CU_TEST(!strcmp(event, KRETPROBE_NAME));
-				found = true;
-				break;
-			default:
-				break;
-			}
-		}
-		CU_TEST(found);
-	}
-	tracefs_list_free(kprobes);
-	CU_TEST(i == 3);
-
-	kprobes = tracefs_get_kprobes(TRACEFS_KPROBE);
-	CU_TEST(kprobes != NULL);
-
-	for (i = 0; kprobes[i]; i++) {
-		char *system = strtok(kprobes[i], "/");
-		char *event = strtok(NULL, "");
-		bool found = false;
-		if (!strcmp(system, KPROBE_1_GROUP)) {
-			CU_TEST(!strcmp(event, KPROBE_1_NAME));
-			found = true;
-		} else if (!strcmp(system, KPROBE_2_GROUP)) {
-			CU_TEST(!strcmp(event, KPROBE_2_NAME));
-			found = true;
-		}
-		CU_TEST(found);
-	}
-	tracefs_list_free(kprobes);
-	CU_TEST(i == 2);
-
-	kprobes = tracefs_get_kprobes(TRACEFS_KRETPROBE);
-	CU_TEST(kprobes != NULL);
-
-	for (i = 0; kprobes[i]; i++) {
-		char *system = strtok(kprobes[i], "/");
-		char *event = strtok(NULL, "");
-		bool found = false;
-		if (!strcmp(system, KPROBE_2_GROUP)) {
-			CU_TEST(!strcmp(event, KRETPROBE_NAME));
-			found = true;
-		}
-		CU_TEST(found);
-	}
-	tracefs_list_free(kprobes);
-	CU_TEST(i == 1);
-
-	ret = tracefs_event_enable(instance, KPROBE_1_GROUP, KPROBE_1_NAME);
-	CU_TEST(ret == 0);
-	ret = tracefs_event_enable(instance, KPROBE_2_GROUP, KPROBE_2_NAME);
-	CU_TEST(ret == 0);
-	ret = tracefs_event_enable(instance, KPROBE_2_GROUP, KRETPROBE_NAME);
-	CU_TEST(ret == 0);
-
-	ret = tracefs_kprobe_clear_all(false);
-	CU_TEST(ret < 0);
-
-	ret = tracefs_kprobe_clear_probe(KPROBE_2_GROUP, NULL, false);
-	CU_TEST(ret < 0);
-
-	ret = tracefs_kprobe_clear_probe(KPROBE_2_GROUP, NULL, true);
-	CU_TEST(ret == 0);
-
-	kprobes = tracefs_get_kprobes(TRACEFS_ALL_KPROBES);
-	CU_TEST(kprobes != NULL);
-
-	for (i = 0; kprobes[i]; i++) {
-		char *system = strtok(kprobes[i], "/");
-		char *event = strtok(NULL, "");
-		bool found = false;
-		if (!strcmp(system, KPROBE_1_GROUP)) {
-			CU_TEST(!strcmp(event, KPROBE_1_NAME));
-			found = true;
-		}
-		CU_TEST(found);
-	}
-	tracefs_list_free(kprobes);
-	CU_TEST(i == 1);
-
-	ret = tracefs_kprobe_clear_all(true);
-	CU_TEST(ret == 0);
-
-	kprobes = tracefs_get_kprobes(TRACEFS_ALL_KPROBES);
-	CU_TEST(kprobes != NULL);
-
-	CU_TEST(kprobes[0] == NULL);
-	tracefs_list_free(kprobes);
-
 	tracefs_put_tracing_file(inst_file);
 	free(fname);
 
@@ -1442,4 +1513,5 @@ void test_tracefs_lib(void)
 		    test_custom_trace_dir);
 	CU_add_test(suite, "ftrace marker",
 		    test_ftrace_marker);
+	CU_add_test(suite, "kprobes", test_kprobes);
 }
-- 
2.31.1

[PATCH v4 07/10] libtracefs: Rename tracefs_synth_init API

[Tzvetomir Stoyanov (VMware)]

In order to be consistent with the others library APIs, the
tracefs_synth_init() is renamed to tracefs_synth_alloc().

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 Documentation/libtracefs-synth.txt  | 20 ++++++++++----------
 Documentation/libtracefs-synth2.txt | 10 +++++-----
 include/tracefs.h                   | 18 +++++++++---------
 src/tracefs-hist.c                  | 22 +++++++++++-----------
 src/tracefs-sqlhist.c               |  6 +++---
 5 files changed, 38 insertions(+), 38 deletions(-)

diff --git a/Documentation/libtracefs-synth.txt b/Documentation/libtracefs-synth.txt
index 77076e1..2fd9019 100644
--- a/Documentation/libtracefs-synth.txt
+++ b/Documentation/libtracefs-synth.txt
@@ -3,7 +3,7 @@ libtracefs(3)
 
 NAME
 ----
-tracefs_synth_init, tracefs_synth_add_match_field, tracefs_synth_add_compare_field, tracefs_synth_add_start_field,
+tracefs_synth_alloc, tracefs_synth_add_match_field, tracefs_synth_add_compare_field, tracefs_synth_add_start_field,
 tracefs_synth_add_end_field, tracefs_synth_append_start_filter, tracefs_synth_append_end_filter, tracefs_synth_free,
 - Creation of a synthetic event descriptor
 
@@ -13,7 +13,7 @@ SYNOPSIS
 --
 *#include <tracefs.h>*
 
-struct tracefs_synth pass:[*]tracefs_synth_init(struct tep_handle pass:[*]tep,
+struct tracefs_synth pass:[*]tracefs_synth_alloc(struct tep_handle pass:[*]tep,
 					 const char pass:[*]name,
 					 const char pass:[*]start_system,
 					 const char pass:[*]start_event,
@@ -69,7 +69,7 @@ as a field for both events to calculate the delta in nanoseconds, or use
 *TRACEFS_TIMESTAMP_USECS" as the compare fields for both events to calculate the
 delta in microseconds. This is used as the example below.
 
-*tracefs_synth_init*() allocates and initializes a synthetic event.
+*tracefs_synth_alloc*() allocates and initializes a synthetic event.
 It does not create the synthetic event, but supplies the minimal information
 to do so. See *tracefs_synth_create*(3) for how to create the synthetic
 event in the system. It requires a _tep_ handler that can be created by
@@ -156,11 +156,11 @@ _field_, _compare_, and _val_ are ignored unless _type_ is equal to
 filters on the ending event.
 
 *tracefs_synth_free*() frees the allocated descriptor returned by
-*tracefs_synth_init*().
+*tracefs_synth_alloc*().
 
 RETURN VALUE
 ------------
-*tracefs_synth_init*() returns an allocated struct tracefs_synth descriptor
+*tracefs_synth_alloc*() returns an allocated struct tracefs_synth descriptor
 on sucess or NULL on error.
 
 All other functions that return an integer returns zero on success or -1
@@ -209,11 +209,11 @@ static void make_event(void)
 	tep = tracefs_local_events(NULL);
 
 	/* Initialize the synthetic event */
-	synth = tracefs_synth_init(tep, "wakeup_lat",
-				   NULL, start_event,
-				   NULL, end_event,
-				   start_field, end_field,
-				   match_name);
+	synth = tracefs_synth_alloc(tep, "wakeup_lat",
+				    NULL, start_event,
+				    NULL, end_event,
+				    start_field, end_field,
+				    match_name);
 
 	/* The tep is no longer needed */
 	tep_free(tep);
diff --git a/Documentation/libtracefs-synth2.txt b/Documentation/libtracefs-synth2.txt
index 4c44253..f734b44 100644
--- a/Documentation/libtracefs-synth2.txt
+++ b/Documentation/libtracefs-synth2.txt
@@ -142,11 +142,11 @@ static void make_event(void)
 	tep = tracefs_local_events(NULL);
 
 	/* Initialize the synthetic event */
-	synth = tracefs_synth_init(tep, "wakeup_lat",
-				   NULL, start_event,
-				   NULL, end_event,
-				   start_field, end_field,
-				   match_name);
+	synth = tracefs_synth_alloc(tep, "wakeup_lat",
+				    NULL, start_event,
+				    NULL, end_event,
+				    start_field, end_field,
+				    match_name);
 
 	/* The tep is no longer needed */
 	tep_free(tep);
diff --git a/include/tracefs.h b/include/tracefs.h
index 8377ade..ad8a7f5 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -478,15 +478,15 @@ enum tracefs_synth_handler {
 	TRACEFS_SYNTH_HANDLE_CHANGE,
 };
 
-struct tracefs_synth *tracefs_synth_init(struct tep_handle *tep,
-					 const char *name,
-					 const char *start_system,
-					 const char *start_event,
-					 const char *end_system,
-					 const char *end_event,
-					 const char *start_match_field,
-					 const char *end_match_field,
-					 const char *match_name);
+struct tracefs_synth *tracefs_synth_alloc(struct tep_handle *tep,
+					  const char *name,
+					  const char *start_system,
+					  const char *start_event,
+					  const char *end_system,
+					  const char *end_event,
+					  const char *start_match_field,
+					  const char *end_match_field,
+					  const char *match_name);
 int tracefs_synth_add_match_field(struct tracefs_synth *synth,
 				  const char *start_match_field,
 				  const char *end_match_field,
diff --git a/src/tracefs-hist.c b/src/tracefs-hist.c
index 27bab00..9009dba 100644
--- a/src/tracefs-hist.c
+++ b/src/tracefs-hist.c
@@ -692,7 +692,7 @@ static void action_free(struct action *action)
  * @synth: The tracefs_synth descriptor
  *
  * Frees the resources allocated for a @synth created with
- * tracefs_synth_init(). It does not touch the system. That is,
+ * tracefs_synth_alloc(). It does not touch the system. That is,
  * any synthetic event created, will not be destroyed by this
  * function.
  */
@@ -890,7 +890,7 @@ synth_init_from(struct tep_handle *tep, const char *start_system,
 }
 
 /**
- * tracefs_synth_init - create a new tracefs_synth instance
+ * tracefs_synth_alloc - create a new tracefs_synth instance
  * @tep: The tep handle that holds the events to work on
  * @name: The name of the synthetic event being created
  * @start_system: The name of the system of the start event (can be NULL)
@@ -933,15 +933,15 @@ synth_init_from(struct tep_handle *tep, const char *start_system,
  * event on the system is not created. That needs to be done with
  * tracefs_synth_create().
  */
-struct tracefs_synth *tracefs_synth_init(struct tep_handle *tep,
-					 const char *name,
-					 const char *start_system,
-					 const char *start_event_name,
-					 const char *end_system,
-					 const char *end_event_name,
-					 const char *start_match_field,
-					 const char *end_match_field,
-					 const char *match_name)
+struct tracefs_synth *tracefs_synth_alloc(struct tep_handle *tep,
+					  const char *name,
+					  const char *start_system,
+					  const char *start_event_name,
+					  const char *end_system,
+					  const char *end_event_name,
+					  const char *start_match_field,
+					  const char *end_match_field,
+					  const char *match_name)
 {
 	struct tep_event *end_event;
 	struct tracefs_synth *synth;
diff --git a/src/tracefs-sqlhist.c b/src/tracefs-sqlhist.c
index d77ce86..016f3eb 100644
--- a/src/tracefs-sqlhist.c
+++ b/src/tracefs-sqlhist.c
@@ -1419,9 +1419,9 @@ static struct tracefs_synth *build_synth(struct tep_handle *tep,
 	assign_match(start_system, start_event, match,
 		     &start_match, &end_match);
 
-	synth = tracefs_synth_init(tep, name, start_system,
-				   start_event, end_system, end_event,
-				   start_match, end_match, NULL);
+	synth = tracefs_synth_alloc(tep, name, start_system,
+				    start_event, end_system, end_event,
+				    start_match, end_match, NULL);
 	if (!synth)
 		return synth_init_error(tep, table);
 
-- 
2.31.1

[PATCH v4 08/10] libtracefs: Use the internal dynamic events API when creating synthetic events

[Tzvetomir Stoyanov (VMware)]

Synthetic events are type of ftrace dynamic events. The tracefs library
has dedicated APIs to manage dynamic events of all types. In order the
code to be consistent, the creation of synthetic events inside the
library is reimplemented with these new dynamic events APIs.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 src/tracefs-hist.c | 103 +++++++++++++++++++++------------------------
 1 file changed, 47 insertions(+), 56 deletions(-)

diff --git a/src/tracefs-hist.c b/src/tracefs-hist.c
index 9009dba..08bb2da 100644
--- a/src/tracefs-hist.c
+++ b/src/tracefs-hist.c
@@ -661,6 +661,7 @@ struct tracefs_synth {
 	struct tep_event	*end_event;
 	struct action		*actions;
 	struct action		**next_action;
+	struct tracefs_dynevent	*dyn_event;
 	char			*name;
 	char			**synthetic_fields;
 	char			**synthetic_args;
@@ -719,6 +720,7 @@ void tracefs_synth_free(struct tracefs_synth *synth)
 		synth->actions = action->next;
 		action_free(action);
 	}
+	tracefs_dynevent_free(synth->dyn_event);
 
 	free(synth);
 }
@@ -889,6 +891,28 @@ synth_init_from(struct tep_handle *tep, const char *start_system,
 	return synth;
 }
 
+static int alloc_synthetic_event(struct tracefs_synth *synth)
+{
+	char *synthetic_format;
+	const char *field;
+	int i;
+
+	synthetic_format = strdup("");
+	if (!synthetic_format)
+		return -1;
+
+	for (i = 0; synth->synthetic_fields && synth->synthetic_fields[i]; i++) {
+		field = synth->synthetic_fields[i];
+		synthetic_format = append_string(synthetic_format, " ", field);
+	}
+
+	synth->dyn_event = dynevent_alloc(TRACEFS_DYNEVENT_SYNTH, NULL,
+					  synth->name, NULL, synthetic_format);
+	free(synthetic_format);
+
+	return synth->dyn_event ? 0 : -1;
+}
+
 /**
  * tracefs_synth_alloc - create a new tracefs_synth instance
  * @tep: The tep handle that holds the events to work on
@@ -1609,38 +1633,6 @@ int tracefs_synth_save(struct tracefs_synth *synth,
 	return 0;
 }
 
-static char *create_synthetic_event(struct tracefs_synth *synth)
-{
-	char *synthetic_event;
-	const char *field;
-	int i;
-
-	synthetic_event = strdup(synth->name);
-	if (!synthetic_event)
-		return NULL;
-
-	for (i = 0; synth->synthetic_fields && synth->synthetic_fields[i]; i++) {
-		field = synth->synthetic_fields[i];
-		synthetic_event = append_string(synthetic_event, " ", field);
-	}
-
-	return synthetic_event;
-}
-
-static int remove_synthetic(const char *synthetic)
-{
-	char *str;
-	int ret;
-
-	ret = asprintf(&str, "!%s", synthetic);
-	if (ret < 0)
-		return -1;
-
-	ret = tracefs_instance_file_append(NULL, "synthetic_events", str);
-	free(str);
-	return ret < 0 ? -1 : 0;
-}
-
 static int remove_hist(struct tracefs_instance *instance,
 		       struct tep_event *event, const char *hist)
 {
@@ -1919,7 +1911,6 @@ tracefs_synth_get_start_hist(struct tracefs_synth *synth)
 int tracefs_synth_create(struct tracefs_instance *instance,
 			 struct tracefs_synth *synth)
 {
-	char *synthetic_event;
 	char *start_hist = NULL;
 	char *end_hist = NULL;
 	int ret;
@@ -1937,14 +1928,10 @@ int tracefs_synth_create(struct tracefs_instance *instance,
 	if (verify_state(synth) < 0)
 		return -1;
 
-	synthetic_event = create_synthetic_event(synth);
-	if (!synthetic_event)
+	if (!synth->dyn_event && alloc_synthetic_event(synth))
+		return -1;
+	if (!tracefs_dynevent_create(synth->dyn_event))
 		return -1;
-
-	ret = tracefs_instance_file_append(NULL, "synthetic_events",
-					   synthetic_event);
-	if (ret < 0)
-		goto free_synthetic;
 
 	start_hist = create_hist(synth->start_keys, synth->start_vars);
 	start_hist = append_filter(start_hist, synth->start_filter,
@@ -1980,9 +1967,7 @@ int tracefs_synth_create(struct tracefs_instance *instance,
  remove_synthetic:
 	free(end_hist);
 	free(start_hist);
-	remove_synthetic(synthetic_event);
- free_synthetic:
-	free(synthetic_event);
+	tracefs_dynevent_destroy(synth->dyn_event, false);
 	return -1;
 }
 
@@ -2007,7 +1992,6 @@ int tracefs_synth_create(struct tracefs_instance *instance,
 int tracefs_synth_destroy(struct tracefs_instance *instance,
 			  struct tracefs_synth *synth)
 {
-	char *synthetic_event;
 	char *hist;
 	int ret;
 
@@ -2041,11 +2025,7 @@ int tracefs_synth_destroy(struct tracefs_instance *instance,
 	ret = remove_hist(instance, synth->start_event, hist);
 	free(hist);
 
-	synthetic_event = create_synthetic_event(synth);
-	if (!synthetic_event)
-		return -1;
-
-	ret = remove_synthetic(synthetic_event);
+	ret = tracefs_dynevent_destroy(synth->dyn_event, false);
 
 	return ret ? -1 : 0;
 }
@@ -2067,7 +2047,7 @@ int tracefs_synth_show(struct trace_seq *seq,
 		       struct tracefs_instance *instance,
 		       struct tracefs_synth *synth)
 {
-	char *synthetic_event = NULL;
+	bool new_event = false;
 	char *hist = NULL;
 	char *path;
 	int ret = -1;
@@ -2082,16 +2062,19 @@ int tracefs_synth_show(struct trace_seq *seq,
 		return -1;
 	}
 
-	synthetic_event = create_synthetic_event(synth);
-	if (!synthetic_event)
-		return -1;
+	if (!synth->dyn_event) {
+		if (alloc_synthetic_event(synth))
+			return -1;
+		new_event = true;
+	}
 
 	path = trace_find_tracing_dir();
 	if (!path)
 		goto out_free;
 
-	trace_seq_printf(seq, "echo '%s' > %s/synthetic_events\n",
-			 synthetic_event, path);
+	trace_seq_printf(seq, "echo '%s%s %s' > %s/%s\n",
+			 synth->dyn_event->prefix, synth->dyn_event->event,
+			 synth->dyn_event->format, path, synth->dyn_event->trace_file);
 
 	tracefs_put_tracing_file(path);
 	path = tracefs_instance_get_dir(instance);
@@ -2116,10 +2099,18 @@ int tracefs_synth_show(struct trace_seq *seq,
 			 hist, path, synth->end_event->system,
 			 synth->end_event->name);
 
+	if (new_event) {
+		tracefs_dynevent_free(synth->dyn_event);
+		synth->dyn_event = NULL;
+	}
+
 	ret = 0;
  out_free:
-	free(synthetic_event);
 	free(hist);
 	tracefs_put_tracing_file(path);
+	if (new_event) {
+		tracefs_dynevent_free(synth->dyn_event);
+		synth->dyn_event = NULL;
+	}
 	return ret;
 }
-- 
2.31.1

[PATCH v4 09/10] libtracefs: Update kprobes man pages

[Tzvetomir Stoyanov (VMware)]

As there are a lot of changes in the libtracefs kprobes APIs, the
documentation of the library should be updated.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 Documentation/libtracefs-kprobes.txt | 111 +++++++++++++--------------
 Documentation/libtracefs.txt         |   7 ++
 2 files changed, 60 insertions(+), 58 deletions(-)

diff --git a/Documentation/libtracefs-kprobes.txt b/Documentation/libtracefs-kprobes.txt
index c10576e..fedac96 100644
--- a/Documentation/libtracefs-kprobes.txt
+++ b/Documentation/libtracefs-kprobes.txt
@@ -3,7 +3,9 @@ libtracefs(3)
 
 NAME
 ----
-tracefs_kprobe_raw, tracefs_kretprobe_raw, tracefs_get_kprobes, tracefs_kprobe_info, tracefs_kprobe_clear_all, tracefs_kprobe_clear_probe - Create, list, and destroy kprobes
+tracefs_kprobe_alloc, tracefs_kretprobe_alloc, tracefs_kprobe_info,
+tracefs_kprobe_raw, tracefs_kretprobe_raw - Allocate, get, and create kprobes
+
 
 SYNOPSIS
 --------
@@ -11,18 +13,44 @@ SYNOPSIS
 --
 *#include <tracefs.h>*
 
-int tracefs_kprobe_raw(const char pass:[*]system, const char pass:[*]event, const char pass:[*]addr, const char pass:[*]format);
-int tracefs_kretprobe_raw(const char pass:[*]system, const char pass:[*]event, const char pass:[*]addr, const char pass:[*]format);
-char pass:[*]pass:[*]tracefs_get_kprobes(enum tracefs_kprobe_type type);
-enum tracefs_kprobe_type tracefs_kprobe_info(const char pass:[*]group, const char pass:[*]event,
-					     char pass:[*]pass:[*]type, char pass:[*]pass:[*]addr, char pass:[*]pass:[*]format);
-enum tracefs_kprobe_type tracefs_kprobe_type(const char pass:[*]group, const char pass:[*]event)
-int tracefs_kprobe_clear_all(bool force);
-int tracefs_kprobe_clear_probe(const char pass:[*]system, const char pass:[*]event, bool force);
+struct tracefs_dynevent pass:[*]
+*tracefs_kprobe_alloc*(const char pass:[*]_system_, const char pass:[*]_event_,
+		       const char pass:[*]_addr_, const char pass:[*]_format_);
+struct tracefs_dynevent pass:[*]
+*tracefs_kretprobe_alloc*(const char pass:[*]_system_, const char pass:[*]_event_,
+			  const char pass:[*]_addr_, const char pass:[*]_format_, int _max_);
+enum tracefs_dynevent_type *tracefs_kprobe_info*(struct tracefs_dynevent pass:[*]_kprobe_,
+						char pass:[*]pass:[*]_system_, char pass:[*]pass:[*]_event_,
+						char pass:[*]pass:[*]_prefix_, char pass:[*]pass:[*]_addr_,
+						char pass:[*]pass:[*]_format_);
+int *tracefs_kprobe_raw*(const char pass:[*]_system_, const char pass:[*]_event_,
+			 const char pass:[*]_addr_, const char pass:[*]_format_);
+int *tracefs_kretprobe_raw*(const char pass:[*]_system_, const char pass:[*]_event_,
+			    const char pass:[*]_addr_, const char pass:[*]_format_);
 --
 
 DESCRIPTION
 -----------
+*tracefs_kprobe_alloc*() allocates a new kprobe context. The kbrobe is not configured in the system.
+The new kprobe will be in the _system_ group (or kprobes if _system_ is NULL). Have the name of
+_event_ (or _addr_ if _event_ is NULL). Will be inserted to _addr_ (function name, with or without
+offset, or a address). And the _format_ will define the format of the kprobe. See the Linux
+documentation file under: Documentation/trace/kprobetrace.rst
+
+*tracefs_kretprobe_alloc*() is the same as *tracefs_kprobe_alloc*, but allocates context for
+kretprobe. It has one additional parameter, which is optional, _max_ - maxactive count.
+See description of kretprobes in the Documentation/trace/kprobetrace.rst file.
+
+*tracefs_kprobe_info*() returns the type and information of a given _kprobe_. If any of the
+_system_, _event_, _prefix_, _addr_ or _format_ arguments are not NULL, then strings are allocated
+and returned back via these arguments. The _system_ and _event_ holds the system and the name of the
+kprobe. If _prefix_ is non NULL, then it will hold an allocated string that holds the prefix portion
+of the kprobe in the kprobe_events file (the content up to the ":", including it). Note that for
+kretprobes, the max active count is encoded in the prefix srting. If _addr_ is non NULL, it will
+hold the address or function that the kprobe is attached to. If _format_ is non NULL, it will hold
+the format string of the kprobe. Note, that the content in _group_, _event_, _prefix_, _addr_, and
+_format_ must be freed with free(3) if they are set.
+
 *tracefs_kprobe_raw*() will create a kprobe event. If _system_ is NULL, then
 the default "kprobes" is used for the group (event system). Otherwise if _system_
 is specified then the kprobe will be created under the group by that name. The
@@ -36,55 +64,21 @@ document.
 creates a kretprobe instead of a kprobe. The difference is also described
 in the Linux kernel source in the Documentation/trace/kprobetrace.rst file.
 
-*tracefs_get_kprobes*() returns an array of strings (char pass:[*]) that contain
-the registered kprobes and kretprobes depending on the given _type_. If _type_ is
-TRACEFS_ALL_KPROBES, then all kprobes found are returned. If _type_ is
-TRACEFS_KPROBE, then only normal kprobes are returned. If _type_ is
-TRACEFS_KRETPROBE, then only kretprobes are returned.
-The names are in the "system/event" format.
-That is, one string holds both the kprobe's name as well as the group it is
-defined under. These strings are allocated and may be modified with the
-*strtok*(3) and *strtok_r*(3) functions. The string returned must be freed with
-*tracefs_list_free*(3).
-
-*tracefs_kprobe_info*() returns the type of the given kprobe. If _group_ is
-NULL, then the default "kprobes" is used. If _type_ is non NULL, then it will
-hold an allocated string that holds the type portion of the kprobe in the
-kprobe_events file (the content before the ":"). If _addr_ is non NULL, it will
-hold the address or function that the kprobe is attached to. If _format_ is non
-NULL, it will hold the format string of the kprobe. Note, that the content in
-_type_, _addr_, and _format_ must be freed with free(3) if they are set. Even
-in the case of an error, as they may hold information of what caused the error.
-
-*tracefs_kprobe_clear_all*() will try to remove all kprobes that have been
-registered. If the @force flag is set, it will then disable those kprobe events
-if they are enabled and then try to clear the kprobes.
-
-*tracefs_kprobe_clear_probe*() will try to clear specified kprobes. If _system_
-is NULL, then it will only clear the default kprobes under the "kprobes" group.
-If _event_ is NULL, it will clear all kprobes under the given _system_. If the
-_force_ flag is set, then it will disable the given kprobe events before clearing
-them.
-
 RETURN VALUE
 ------------
 
-*tracefs_kprobe_raw*(), *tracefs_kretprobe_raw*(), *tracefs_kprobe_clear_all*(),
-and *tracefs_kprobe_clear_probe*() return 0 on success, or -1 on error.
-
-If a parsing error occurs on *tracefs_kprobe_raw*() or *tracefs_kretprobe_raw*()
-then *tracefs_error_last*(3) may be used to retrieve the error message explaining
-the parsing issue.
+*tracefs_kprobe_raw*() and *tracefs_kretprobe_raw*() return 0 on success, or -1 on error.
+If a parsing error occurs on *tracefs_kprobe_raw*() or *tracefs_kretprobe_raw*() then
+*tracefs_error_last*(3) may be used to retrieve the error message explaining the parsing issue.
 
-*tracefs_get_kprobes*() returns an allocate string list of allocated strings
-on success that must be freed with *tracefs_list_free*(3) and returns
-NULL on error.
+The *tracefs_kprobe_alloc*() and *tracefs_kretprobe_alloc*() APIs return pointer to allocated
+tracefs_dynevent structure, describing the probe. This pointer must be freed by
+*tracefs_dynevent_free*(3).
 
-*tracefs_kprobe_info*() returns the type of the given kprobe. It returns
-TRACEFS_KPROBE for normal kprobes, TRACEFS_KRETPROBE for kretprobes, and
-on error, or if the kprobe is not found TRACEFS_ALL_KPROBES is returned.
-If _type_, _addr_, or _format_ are non NULL, they will contain allocated
-strings that must be freed by free(3) even in the case of error.
+*tracefs_kprobe_info*() returns the type of the given kprobe. It returns TRACEFS_DYNEVENT_KPROBE for
+normal kprobes, TRACEFS_DYNEVENT_KRETPROBE for kretprobes or TRACEFS_DYNEVENT_MAX on error.
+If _system_, _event_, _prefix_, _addr_, or _format_ are non NULL, they will contain allocated
+strings that must be freed by free(3).
 
 ERRORS
 ------
@@ -96,9 +90,10 @@ The following errors are for all the above calls:
 
 *ENOMEM* Memory allocation error.
 
-*tracefs_kprobe_raw*(), *tracefs_kretprobe_raw*() can fail with the following errors:
+*tracefs_kprobe_raw*(), *tracefs_kretprobe_raw*(), *tracefs_kprobe_alloc*(),
+and *tracefs_kretprobe_alloc*() can fail with the following errors:
 
-*EBADMSG* Either _addr_ or _format_ are NULL.
+*EBADMSG* if _addr_ is NULL.
 
 *EINVAL*  Most likely a parsing error occurred (use *tracefs_error_last*(3) to possibly
           see what that error was).
@@ -217,7 +212,7 @@ int main (int argc, char **argv, char **env)
 		exit(-1);
 	}
 
-	tracefs_kprobe_clear_probe(mykprobe, NULL, true);
+	tracefs_kprobe_destroy(NULL, true);
 
 	kprobe_create("open", "do_sys_openat2",
 		      "file=+0($arg2):ustring flags=+0($arg3):x64 mode=+8($arg3):x64\n");
@@ -247,7 +242,7 @@ int main (int argc, char **argv, char **env)
 	} while (waitpid(pid, NULL, WNOHANG) != pid);
 
 	/* Will disable the events */
-	tracefs_kprobe_clear_probe(mykprobe, NULL, true);
+	tracefs_kprobe_destroy(NULL, true);
 	tracefs_instance_destroy(instance);
 	tep_free(tep);
 
@@ -293,5 +288,5 @@ https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
 
 COPYING
 -------
-Copyright \(C) 2020 VMware, Inc. Free use of this software is granted under
+Copyright \(C) 2021 VMware, Inc. Free use of this software is granted under
 the terms of the GNU Public License (GPL).
diff --git a/Documentation/libtracefs.txt b/Documentation/libtracefs.txt
index 2c9eabd..f679002 100644
--- a/Documentation/libtracefs.txt
+++ b/Documentation/libtracefs.txt
@@ -63,6 +63,13 @@ Writing data in the trace buffer:
 
 Control library logs:
 	int *tracefs_set_loglevel*(enum tep_loglevel _level_);
+
+Kprobes and Kretprobes:
+	struct tracefs_dynevent pass:[*] *tracefs_kprobe_alloc*(const char pass:[*]_system_, const char pass:[*]_event_, const char pass:[*]_addr_, const char pass:[*]_format_);
+	struct tracefs_dynevent pass:[*] *tracefs_kretprobe_alloc*(const char pass:[*]_system_, const char pass:[*]_event_, const char pass:[*]_addr_, const char pass:[*]_format_, int _max_);
+	enum tracefs_kprobe_type *tracefs_kprobe_info*(struct tracefs_dynevent pass:[*]_kprobe_, char pass:[*]pass:[*]_system_, char pass:[*]pass:[*]_event_, char pass:[*]pass:[*]_prefix_, char pass:[*]pass:[*]_addr_, char pass:[*]pass:[*]_format_);
+	int *tracefs_kprobe_raw*(const char pass:[*]_system_, const char pass:[*]_event_, const char pass:[*]_addr_, const char pass:[*]_format_);
+	int *tracefs_kretprobe_raw*(const char pass:[*]_system_, const char pass:[*]_event_, const char pass:[*]_addr_, const char pass:[*]_format_);
 --
 
 DESCRIPTION
-- 
2.31.1

[PATCH v4 10/10] libtracefs: Document dynamic events APIs

[Tzvetomir Stoyanov (VMware)]

As a new set of APIs for ftrace dynamic events were added recently,
they must be documented. A new man page is added, describing these
APIs:
  tracefs_dynevent_create();
  tracefs_dynevent_destroy();
  tracefs_dynevent_destroy_all();
  tracefs_dynevent_free();
  tracefs_dynevent_list_free();
  tracefs_dynevent_get_all();

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 Documentation/libtracefs-dynevents.txt | 251 +++++++++++++++++++++++++
 Documentation/libtracefs.txt           |  10 +
 2 files changed, 261 insertions(+)
 create mode 100644 Documentation/libtracefs-dynevents.txt

diff --git a/Documentation/libtracefs-dynevents.txt b/Documentation/libtracefs-dynevents.txt
new file mode 100644
index 0000000..d3b4830
--- /dev/null
+++ b/Documentation/libtracefs-dynevents.txt
@@ -0,0 +1,251 @@
+libtracefs(3)
+=============
+
+NAME
+----
+tracefs_dynevent_create, tracefs_dynevent_destroy, tracefs_dynevent_destroy_all,
+tracefs_dynevent_free, tracefs_dynevent_list_free, tracefs_dynevent_get_all -
+Create, destroy, free and get dynamic events.
+
+SYNOPSIS
+--------
+[verse]
+--
+*#include <tracefs.h>*
+
+struct *tracefs_dynevent*;
+enum *tracefs_dynevent_type*;
+int *tracefs_dynevent_create*(struct tracefs_dynevent pass:[*]_devent_);
+int *tracefs_dynevent_destroy*(struct tracefs_dynevent pass:[*]_devent_, bool _force_);
+int *tracefs_dynevent_destroy_all*(enum tracefs_dynevent_type _types_, bool _force_);
+void *tracefs_dynevent_free*(struct tracefs_dynevent pass:[*]_devent_);
+void *tracefs_dynevent_list_free*(struct tracefs_dynevent pass:[*]pass:[*]_events_);
+struct tracefs_dynevent pass:[*]pass:[*]*tracefs_dynevent_get_all*(enum tracefs_dynevent_type _types_, const char pass:[*]_system_);
+--
+
+DESCRIPTION
+-----------
+
+The *tracefs_dynevent_create*() function creates dynamic event _devent_ in the system.
+
+The *tracefs_dynevent_destroy*() function removes dynamic event _devent_ from the system. If _force_
+is true, the function will attempt to disable all events in all trace instances, before removing
+the dynamic event. The _devent_ context is not freed, use *tracefs_dynevent_free*() to free it.
+
+The *tracefs_dynevent_destroy_all*() function removes all dynamic events of given types from the
+system. The _types_ parameter is a type of specific dynamic event, or a bitmask of dynamic events
+types *tracefs_dynevent_type*, that will be removed. If _types_ is 0, dynamic events from all types
+will be removed.  If _force_ is true, the function will attempt to disable all events in all trace
+instances, before removing the dynamic events.
+
+The *tracefs_dynevent_get_all*() function allocates and returns an array of pointers to dynamic
+events of given types that exist in the system. The last element of the array is a NULL pointer.
+The array must be freed with *tracefs_dynevent_list_free*(). If there are no events a NULL pointer is
+returned. The _types_ parameter is a type of specific dynamic event, or a bitmask of dynamic events
+types *tracefs_dynevent_type*, that will be retrieved. If _types_ is 0, dynamic events from all
+types will be retrieved.
+
+The *tracefs_dynevent_free*() function frees a dynamic event context _devent_.
+
+The *tracefs_dynevent_list_free*() function frees an array of pointers to dynamic event, returned
+by *tracefs_dynevent_get_all()* API.
+
+RETURN VALUE
+------------
+
+*tracefs_dynevent_create*() returns 0 on success, or -1 on error. If a parsing error occurs then
+*tracefs_error_last*(3) may be used to retrieve the error message explaining the parsing issue.
+
+*tracefs_dynevent_destroy*() and *tracefs_dynevent_destroy_all*() return 0 on success, or -1 on
+error. If _force_ is enabled, the functions may fail on disabling the events.
+
+*tracefs_dynevent_get_all*() function returns allocated array of pointers to dynamic events, or NULL
+in case of an error or in case there are no events in the system. That array must be freed by
+*tracefs_dynevent_list_free*().
+
+ERRORS
+------
+The following errors are for all the above calls:
+
+*EPERM* Not run as root user
+
+*ENODEV* dynamic events of requested type are not configured for the running kernel.
+
+*ENOMEM* Memory allocation error.
+
+*tracefs_dynevent_create*() can fail with the following errors:
+
+*EINVAL*  Most likely a parsing error occurred (use *tracefs_error_last*(3) to possibly
+          see what that error was).
+
+Other errors may also happen caused by internal system calls.
+
+EXAMPLE
+-------
+[source,c]
+--
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
+#include <tracefs/tracefs.h>
+
+static struct tep_event *open_event;
+static struct tep_format_field *file_field;
+
+static struct tep_event *openret_event;
+static struct tep_format_field *ret_field;
+
+static int callback(struct tep_event *event, struct tep_record *record,
+		    int cpu, void *data)
+{
+	struct trace_seq seq;
+
+	trace_seq_init(&seq);
+	tep_print_event(event->tep, &seq, record, "%d-%s: ", TEP_PRINT_PID, TEP_PRINT_COMM);
+
+	if (event->id == open_event->id) {
+		trace_seq_puts(&seq, "open file='");
+		tep_print_field(&seq, record->data, file_field);
+		trace_seq_puts(&seq, "'\n");
+	} else if (event->id == openret_event->id) {
+		unsigned long long ret;
+		tep_read_number_field(ret_field, record->data, &ret);
+		trace_seq_printf(&seq, "open ret=%lld\n", ret);
+	} else {
+		goto out;
+	}
+
+	trace_seq_terminate(&seq);
+	trace_seq_do_printf(&seq);
+out:
+	trace_seq_destroy(&seq);
+
+	return 0;
+}
+
+static pid_t run_exec(char **argv, char **env)
+{
+	pid_t pid;
+
+	pid = fork();
+	if (pid)
+		return pid;
+
+	execve(argv[0], argv, env);
+	perror("exec");
+	exit(-1);
+}
+
+const char *mykprobe = "my_kprobes";
+
+int main (int argc, char **argv, char **env)
+{
+	struct tracefs_dynevent *kprobe, *kretprobe;
+	const char *sysnames[] = { mykprobe, NULL };
+	struct tracefs_instance *instance;
+	struct tep_handle *tep;
+	pid_t pid;
+
+	if (argc < 2) {
+		printf("usage: %s command\n", argv[0]);
+		exit(-1);
+	}
+
+	instance = tracefs_instance_create("exec_open");
+	if (!instance) {
+		perror("creating instance");
+		exit(-1);
+	}
+
+	tracefs_dynevent_destroy_all(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE, true);
+
+	kprobe = tracefs_kprobe_alloc(mykprobe, "open", "do_sys_openat2",
+				      "file=+0($arg2):ustring flags=+0($arg3):x64 mode=+8($arg3):x64\n");
+	kretprobe = tracefs_kretprobe_alloc(mykprobe, "openret", "do_sys_openat2", "ret=%ax", 0);
+	if (!kprobe || !kretprobe) {
+		perror("allocating dynamic events");
+		exit(-1);
+	}
+
+	if (tracefs_dynevent_create(kprobe) || tracefs_dynevent_create(kretprobe)){
+		err = tracefs_error_last(NULL);
+		perror("Failed to create kprobes:");
+		if (err && strlen(err))
+			fprintf(stderr, "%s\n", err);
+		exit(-1);
+	}
+
+	tep = tracefs_local_events_system(NULL, sysnames);
+	if (!tep) {
+		perror("reading events");
+		exit(-1);
+	}
+	open_event = tep_find_event_by_name(tep, mykprobe, "open");
+	file_field = tep_find_field(open_event, "file");
+
+	openret_event = tep_find_event_by_name(tep, mykprobe, "openret");
+	ret_field = tep_find_field(openret_event, "ret");
+
+	tracefs_event_enable(instance, mykprobe, NULL);
+	pid = run_exec(&argv[1], env);
+
+	/* Let the child start to run */
+	sched_yield();
+
+	do {
+		tracefs_load_cmdlines(NULL, tep);
+		tracefs_iterate_raw_events(tep, instance, NULL, 0, callback, NULL);
+	} while (waitpid(pid, NULL, WNOHANG) != pid);
+
+	/* Will disable the events */
+	tracefs_dynevent_destroy_all(TRACEFS_DYNEVENT_KPROBE | TRACEFS_DYNEVENT_KRETPROBE, true);
+	tracefs_dynevent_free(kprobe);
+	tracefs_dynevent_free(kretprobe);
+	tracefs_instance_destroy(instance);
+	tep_free(tep);
+
+	return 0;
+}
+--
+
+FILES
+-----
+[verse]
+--
+*tracefs.h*
+	Header file to include in order to have access to the library APIs.
+*-ltracefs*
+	Linker switch to add when building a program that uses the library.
+--
+
+SEE ALSO
+--------
+_libtracefs(3)_,
+_libtraceevent(3)_,
+_trace-cmd(1)_
+
+AUTHOR
+------
+[verse]
+--
+*Steven Rostedt* <rostedt@goodmis.org>
+*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>
+*Yordan Karadzhov* <y.karadz@gmail.com>
+--
+REPORTING BUGS
+--------------
+Report bugs to  <linux-trace-devel@vger.kernel.org>
+
+LICENSE
+-------
+libtracefs is Free Software licensed under the GNU LGPL 2.1
+
+RESOURCES
+---------
+https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
+
+COPYING
+-------
+Copyright \(C) 2021 VMware, Inc. Free use of this software is granted under
+the terms of the GNU Public License (GPL).
diff --git a/Documentation/libtracefs.txt b/Documentation/libtracefs.txt
index f679002..9ffb6ab 100644
--- a/Documentation/libtracefs.txt
+++ b/Documentation/libtracefs.txt
@@ -64,6 +64,16 @@ Writing data in the trace buffer:
 Control library logs:
 	int *tracefs_set_loglevel*(enum tep_loglevel _level_);
 
+Dynamic event generic APIs:
+	struct *tracefs_dynevent*;
+	enum *tracefs_dynevent_type*;
+	int *tracefs_dynevent_create*(struct tracefs_dynevent pass:[*]_devent_);
+	int *tracefs_dynevent_destroy*(struct tracefs_dynevent pass:[*]_devent_, bool _force_);
+	int *tracefs_dynevent_destroy_all*(enum tracefs_dynevent_type _types_, bool _force_);
+	void *tracefs_dynevent_free*(struct tracefs_dynevent pass:[*]_devent_);
+	void *tracefs_dynevent_list_free*(struct tracefs_dynevent pass:[*]pass:[*]_events_);
+	struct tracefs_dynevent pass:[*]pass:[*]*tracefs_dynevent_get_all*(enum tracefs_dynevent_type _types_, const char pass:[*]_system_);
+
 Kprobes and Kretprobes:
 	struct tracefs_dynevent pass:[*] *tracefs_kprobe_alloc*(const char pass:[*]_system_, const char pass:[*]_event_, const char pass:[*]_addr_, const char pass:[*]_format_);
 	struct tracefs_dynevent pass:[*] *tracefs_kretprobe_alloc*(const char pass:[*]_system_, const char pass:[*]_event_, const char pass:[*]_addr_, const char pass:[*]_format_, int _max_);
-- 
2.31.1

Re: [PATCH v4 08/10] libtracefs: Use the internal dynamic events API when creating synthetic events

[Yordan Karadzhov]

On 4.11.21 г. 13:10, Tzvetomir Stoyanov (VMware) wrote:
> Synthetic events are type of ftrace dynamic events. The tracefs library
> has dedicated APIs to manage dynamic events of all types. In order the
> code to be consistent, the creation of synthetic events inside the
> library is reimplemented with these new dynamic events APIs.
> 
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> ---
>   src/tracefs-hist.c | 103 +++++++++++++++++++++------------------------
>   1 file changed, 47 insertions(+), 56 deletions(-)
> 
> diff --git a/src/tracefs-hist.c b/src/tracefs-hist.c
> index 9009dba..08bb2da 100644
> --- a/src/tracefs-hist.c
> +++ b/src/tracefs-hist.c
> @@ -661,6 +661,7 @@ struct tracefs_synth {
>   	struct tep_event	*end_event;
>   	struct action		*actions;
>   	struct action		**next_action;
> +	struct tracefs_dynevent	*dyn_event;
>   	char			*name;
>   	char			**synthetic_fields;
>   	char			**synthetic_args;
> @@ -719,6 +720,7 @@ void tracefs_synth_free(struct tracefs_synth *synth)
>   		synth->actions = action->next;
>   		action_free(action);
>   	}
> +	tracefs_dynevent_free(synth->dyn_event);
>   
>   	free(synth);
>   }
> @@ -889,6 +891,28 @@ synth_init_from(struct tep_handle *tep, const char *start_system,
>   	return synth;
>   }
>   
> +static int alloc_synthetic_event(struct tracefs_synth *synth)
> +{
> +	char *synthetic_format;
> +	const char *field;
> +	int i;
> +
> +	synthetic_format = strdup("");
> +	if (!synthetic_format)
> +		return -1;
> +
> +	for (i = 0; synth->synthetic_fields && synth->synthetic_fields[i]; i++) {
> +		field = synth->synthetic_fields[i];
> +		synthetic_format = append_string(synthetic_format, " ", field);
> +	}
> +
> +	synth->dyn_event = dynevent_alloc(TRACEFS_DYNEVENT_SYNTH, NULL,
> +					  synth->name, NULL, synthetic_format);
> +	free(synthetic_format);
> +
> +	return synth->dyn_event ? 0 : -1;
> +}
> +
>   /**
>    * tracefs_synth_alloc - create a new tracefs_synth instance
>    * @tep: The tep handle that holds the events to work on
> @@ -1609,38 +1633,6 @@ int tracefs_synth_save(struct tracefs_synth *synth,
>   	return 0;
>   }
>   
> -static char *create_synthetic_event(struct tracefs_synth *synth)
> -{
> -	char *synthetic_event;
> -	const char *field;
> -	int i;
> -
> -	synthetic_event = strdup(synth->name);
> -	if (!synthetic_event)
> -		return NULL;
> -
> -	for (i = 0; synth->synthetic_fields && synth->synthetic_fields[i]; i++) {
> -		field = synth->synthetic_fields[i];
> -		synthetic_event = append_string(synthetic_event, " ", field);
> -	}
> -
> -	return synthetic_event;
> -}
> -
> -static int remove_synthetic(const char *synthetic)
> -{
> -	char *str;
> -	int ret;
> -
> -	ret = asprintf(&str, "!%s", synthetic);
> -	if (ret < 0)
> -		return -1;
> -
> -	ret = tracefs_instance_file_append(NULL, "synthetic_events", str);
> -	free(str);
> -	return ret < 0 ? -1 : 0;
> -}
> -
>   static int remove_hist(struct tracefs_instance *instance,
>   		       struct tep_event *event, const char *hist)
>   {
> @@ -1919,7 +1911,6 @@ tracefs_synth_get_start_hist(struct tracefs_synth *synth)
>   int tracefs_synth_create(struct tracefs_instance *instance,

I wonder is it really necessary this function to take 'tracefs_instance' as argument?

I remember from conversations with Steven that setting the histograms/triggers in the top instance will have the same 
effect. Or maybe I am wrong? The same question applies for the 'destroy' API.

Thanks!
Yordan


>   			 struct tracefs_synth *synth)
>   {
> -	char *synthetic_event;
>   	char *start_hist = NULL;
>   	char *end_hist = NULL;
>   	int ret;
> @@ -1937,14 +1928,10 @@ int tracefs_synth_create(struct tracefs_instance *instance,
>   	if (verify_state(synth) < 0)
>   		return -1;
>   
> -	synthetic_event = create_synthetic_event(synth);
> -	if (!synthetic_event)
> +	if (!synth->dyn_event && alloc_synthetic_event(synth))
> +		return -1;
> +	if (!tracefs_dynevent_create(synth->dyn_event))
>   		return -1;
> -
> -	ret = tracefs_instance_file_append(NULL, "synthetic_events",
> -					   synthetic_event);
> -	if (ret < 0)
> -		goto free_synthetic;
>   
>   	start_hist = create_hist(synth->start_keys, synth->start_vars);
>   	start_hist = append_filter(start_hist, synth->start_filter,
> @@ -1980,9 +1967,7 @@ int tracefs_synth_create(struct tracefs_instance *instance,
>    remove_synthetic:
>   	free(end_hist);
>   	free(start_hist);
> -	remove_synthetic(synthetic_event);
> - free_synthetic:
> -	free(synthetic_event);
> +	tracefs_dynevent_destroy(synth->dyn_event, false);
>   	return -1;
>   }
>   
> @@ -2007,7 +1992,6 @@ int tracefs_synth_create(struct tracefs_instance *instance,
>   int tracefs_synth_destroy(struct tracefs_instance *instance,
>   			  struct tracefs_synth *synth)
>   {
> -	char *synthetic_event;
>   	char *hist;
>   	int ret;
>   
> @@ -2041,11 +2025,7 @@ int tracefs_synth_destroy(struct tracefs_instance *instance,
>   	ret = remove_hist(instance, synth->start_event, hist);
>   	free(hist);
>   
> -	synthetic_event = create_synthetic_event(synth);
> -	if (!synthetic_event)
> -		return -1;
> -
> -	ret = remove_synthetic(synthetic_event);
> +	ret = tracefs_dynevent_destroy(synth->dyn_event, false);
>   
>   	return ret ? -1 : 0;
>   }
> @@ -2067,7 +2047,7 @@ int tracefs_synth_show(struct trace_seq *seq,
>   		       struct tracefs_instance *instance,
>   		       struct tracefs_synth *synth)
>   {
> -	char *synthetic_event = NULL;
> +	bool new_event = false;
>   	char *hist = NULL;
>   	char *path;
>   	int ret = -1;
> @@ -2082,16 +2062,19 @@ int tracefs_synth_show(struct trace_seq *seq,
>   		return -1;
>   	}
>   
> -	synthetic_event = create_synthetic_event(synth);
> -	if (!synthetic_event)
> -		return -1;
> +	if (!synth->dyn_event) {
> +		if (alloc_synthetic_event(synth))
> +			return -1;
> +		new_event = true;
> +	}
>   
>   	path = trace_find_tracing_dir();
>   	if (!path)
>   		goto out_free;
>   
> -	trace_seq_printf(seq, "echo '%s' > %s/synthetic_events\n",
> -			 synthetic_event, path);
> +	trace_seq_printf(seq, "echo '%s%s %s' > %s/%s\n",
> +			 synth->dyn_event->prefix, synth->dyn_event->event,
> +			 synth->dyn_event->format, path, synth->dyn_event->trace_file);
>   
>   	tracefs_put_tracing_file(path);
>   	path = tracefs_instance_get_dir(instance);
> @@ -2116,10 +2099,18 @@ int tracefs_synth_show(struct trace_seq *seq,
>   			 hist, path, synth->end_event->system,
>   			 synth->end_event->name);
>   
> +	if (new_event) {
> +		tracefs_dynevent_free(synth->dyn_event);
> +		synth->dyn_event = NULL;
> +	}
> +
>   	ret = 0;
>    out_free:
> -	free(synthetic_event);
>   	free(hist);
>   	tracefs_put_tracing_file(path);
> +	if (new_event) {
> +		tracefs_dynevent_free(synth->dyn_event);
> +		synth->dyn_event = NULL;
> +	}
>   	return ret;
>   }
> 

Re: [PATCH v4 08/10] libtracefs: Use the internal dynamic events API when creating synthetic events

[Steven Rostedt]

On Thu, 4 Nov 2021 14:47:34 +0200
Yordan Karadzhov <y.karadz@gmail.com> wrote:

> > @@ -1919,7 +1911,6 @@ tracefs_synth_get_start_hist(struct tracefs_synth *synth)
> >   int tracefs_synth_create(struct tracefs_instance *instance,  
> 
> I wonder is it really necessary this function to take 'tracefs_instance' as argument?
> 
> I remember from conversations with Steven that setting the histograms/triggers in the top instance will have the same 
> effect. Or maybe I am wrong? The same question applies for the 'destroy' API.

Good point.

Yeah, let's make the events global, and just use the top level for creation
and destruction. As events added to the system affect all instances, they
should only be done at the top level.

-- Steve

Re: [PATCH v4 01/10] libtracefs: New APIs for dynamic events

[Steven Rostedt]

On Thu,  4 Nov 2021 13:10:38 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> ---
>  include/tracefs-local.h |  18 ++
>  include/tracefs.h       |  19 ++
>  src/Makefile            |   1 +
>  src/tracefs-dynevents.c | 689 ++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 727 insertions(+)
>  create mode 100644 src/tracefs-dynevents.c
> 
> diff --git a/include/tracefs-local.h b/include/tracefs-local.h
> index 684eccf..f1a532c 100644
> --- a/include/tracefs-local.h
> +++ b/include/tracefs-local.h
> @@ -94,4 +94,22 @@ int synth_add_start_field(struct tracefs_synth *synth,
>  			  const char *start_field,
>  			  const char *name,
>  			  enum tracefs_hist_key_type type);
> +
> +/* Internal interface for ftrace dynamic events */
> +
> +struct tracefs_dynevent {
> +	char *trace_file;
> +	char *prefix;
> +	char *system;
> +	char *event;
> +	char *address;
> +	char *format;
> +	enum tracefs_dynevent_type type;
> +};
> +
> +struct tracefs_dynevent *
> +dynevent_alloc(enum tracefs_dynevent_type type, const char *system,
> +	       const char *event, const char *address, const char *format);
> +int dynevent_get_count(enum tracefs_dynevent_type types, const char *system);
> +
>  #endif /* _TRACE_FS_LOCAL_H */
> diff --git a/include/tracefs.h b/include/tracefs.h
> index a2cda30..81f22af 100644
> --- a/include/tracefs.h
> +++ b/include/tracefs.h
> @@ -238,6 +238,25 @@ ssize_t tracefs_trace_pipe_stream(int fd, struct tracefs_instance *instance, int
>  ssize_t tracefs_trace_pipe_print(struct tracefs_instance *instance, int flags);
>  void tracefs_trace_pipe_stop(struct tracefs_instance *instance);
>  
> +/* Dynamic events */
> +struct tracefs_dynevent;
> +enum tracefs_dynevent_type {
> +	TRACEFS_DYNEVENT_KPROBE		= 1 << 0,
> +	TRACEFS_DYNEVENT_KRETPROBE	= 1 << 1,
> +	TRACEFS_DYNEVENT_UPROBE		= 1 << 2,
> +	TRACEFS_DYNEVENT_URETPROBE	= 1 << 3,
> +	TRACEFS_DYNEVENT_EPROBE		= 1 << 4,
> +	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(enum tracefs_dynevent_type types, bool force);
> +void tracefs_dynevent_free(struct tracefs_dynevent *devent);
> +void tracefs_dynevent_list_free(struct tracefs_dynevent **events);


> +struct tracefs_dynevent **
> +tracefs_dynevent_get_all(enum tracefs_dynevent_type types, const char *system);

The above still takes more than one type, thus it should be an integer.

That's because declaring it as an enum means that it should not take:

	TRACEFS_DYNEVENT_EPROBE | TRACEFS_DYNEVENT_KPROBE

as an argument, because the above is not one of the enums.

Unsigned int is good enough (we don't expect to have more than 32 types).


> +
>  enum tracefs_kprobe_type {
>  	TRACEFS_ALL_KPROBES,
>  	TRACEFS_KPROBE,
> diff --git a/src/Makefile b/src/Makefile
> index 4e38d98..99cd7da 100644
> --- a/src/Makefile
> +++ b/src/Makefile
> @@ -11,6 +11,7 @@ OBJS += tracefs-marker.o
>  OBJS += tracefs-kprobes.o
>  OBJS += tracefs-hist.o
>  OBJS += tracefs-filter.o
> +OBJS += tracefs-dynevents.o
>  
>  # Order matters for the the three below
>  OBJS += sqlhist-lex.o
> diff --git a/src/tracefs-dynevents.c b/src/tracefs-dynevents.c
> new file mode 100644
> index 0000000..0437629
> --- /dev/null
> +++ b/src/tracefs-dynevents.c
> @@ -0,0 +1,689 @@
> +// SPDX-License-Identifier: LGPL-2.1
> +/*
> + * Copyright (C) 2021 VMware Inc, Steven Rostedt <rostedt@goodmis.org>
> + *
> + * Updates:
> + * Copyright (C) 2021, VMware, Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
> + *
> + */
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <dirent.h>
> +#include <unistd.h>
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <limits.h>
> +
> +#include "tracefs.h"
> +#include "tracefs-local.h"
> +
> +#define DYNEVENTS_EVENTS "dynamic_events"
> +#define KPROBE_EVENTS "kprobe_events"
> +#define UPROBE_EVENTS "uprobe_events"
> +#define SYNTH_EVENTS "synthetic_events"
> +#define DYNEVENTS_DEFAULT_GROUP "dynamic"
> +
> +struct dyn_events_desc;
> +static int dyn_generic_parse(struct dyn_events_desc *,
> +			     const char *, char *, struct tracefs_dynevent **);
> +static int dyn_synth_parse(struct dyn_events_desc *,
> +			   const char *, char *, struct tracefs_dynevent **);
> +static int dyn_generic_del(struct dyn_events_desc *, struct tracefs_dynevent *);
> +static int dyn_synth_del(struct dyn_events_desc *, struct tracefs_dynevent *);
> +
> +struct dyn_events_desc {
> +	enum tracefs_dynevent_type type;
> +	const char *file;
> +	const char *prefix;
> +	int (*del)(struct dyn_events_desc *desc, struct tracefs_dynevent *dyn);
> +	int (*parse)(struct dyn_events_desc *desc, const char *group,
> +				char *line, struct tracefs_dynevent **ret_dyn);
> +} dynevents[] = {
> +	{TRACEFS_DYNEVENT_KPROBE, NULL, "p", dyn_generic_del, dyn_generic_parse},
> +	{TRACEFS_DYNEVENT_KRETPROBE, NULL, "r", dyn_generic_del, dyn_generic_parse},
> +	{TRACEFS_DYNEVENT_UPROBE, NULL, "p", dyn_generic_del, dyn_generic_parse},
> +	{TRACEFS_DYNEVENT_URETPROBE, NULL, "r", dyn_generic_del, dyn_generic_parse},
> +	{TRACEFS_DYNEVENT_EPROBE, NULL, "e", dyn_generic_del, dyn_generic_parse},
> +	{TRACEFS_DYNEVENT_SYNTH, NULL, "s", dyn_synth_del, dyn_synth_parse},
> +};
> +
> +/* get position of the first set bit */
> +static inline int bit_index(unsigned int bits)
> +{
> +	int i = 0;
> +
> +	while (bits) {
> +		if (bits & 0x1)
> +			return i;
> +		bits >>= 1;
> +		i++;
> +	}
> +
> +	return -1;
> +}

Use ffs() instead.

  man ffs

> +
> +static int dyn_generic_del(struct dyn_events_desc *desc, struct tracefs_dynevent *dyn)
> +{
> +	char *str;
> +	int ret;
> +
> +	if (dyn->system)
> +		ret = asprintf(&str, "-:%s/%s", dyn->system, dyn->event);
> +	else
> +		ret = asprintf(&str, "-:%s", dyn->event);
> +
> +	if (ret < 0)
> +		return -1;
> +
> +	ret = tracefs_instance_file_append(NULL, desc->file, str);
> +	free(str);
> +
> +	return ret < 0 ? ret : 0;
> +}
> +
> +/**
> + * tracefs_dynevent_free - Free a dynamic event context
> + * @devent: Pointer to a dynamic event context
> + *
> + * The dynamic event, described by this context, is not
> + * removed from the system by this API. It only frees the memory.
> + */
> +void tracefs_dynevent_free(struct tracefs_dynevent *devent)
> +{
> +	if (!devent)
> +		return;
> +	free(devent->system);
> +	free(devent->event);
> +	free(devent->address);
> +	free(devent->format);
> +	free(devent->prefix);
> +	free(devent->trace_file);
> +	free(devent);
> +}
> +
> +static void parse_prefix(char *word, char **prefix, char **system, char **name)
> +{
> +	char *sav;
> +
> +	*prefix = NULL;
> +	*system = NULL;
> +	*name = NULL;
> +
> +	*prefix = strtok_r(word, ":", &sav);
> +	*system = strtok_r(NULL, "/", &sav);
> +	if (!(*system))
> +		return;
> +
> +	*name = strtok_r(NULL, " ", &sav);
> +	if (!(*name)) {
> +		*name = *system;
> +		*system = NULL;
> +	}
> +}
> +
> +/*
> + * Parse lines from dynamic_events, kprobe_events and uprobe_events files
> + * PREFIX[:[SYSTEM/]EVENT] [ADDRSS] [FORMAT]
> + */
> +static int dyn_generic_parse(struct dyn_events_desc *desc, const char *group,
> +			     char *line, struct tracefs_dynevent **ret_dyn)
> +{
> +	struct tracefs_dynevent *dyn;
> +	char *word;
> +	char *format = NULL;
> +	char *address;
> +	char *system;
> +	char *prefix;
> +	char *event;
> +	char *sav;
> +
> +	if (strncmp(line, desc->prefix, strlen(desc->prefix)))
> +		return -1;
> +
> +	word = strtok_r(line, " ", &sav);
> +	if (!word || *word == '\0')
> +		return -1;
> +
> +	parse_prefix(word, &prefix, &system, &event);
> +	if (!prefix)
> +		return -1;
> +
> +	if (desc->type != TRACEFS_DYNEVENT_SYNTH) {
> +		address = strtok_r(NULL, " ", &sav);
> +		if (!address || *address == '\0')
> +			return -1;
> +	}
> +
> +	format = strtok_r(NULL, "", &sav);
> +
> +	/* KPROBEs and UPROBEs share the same prefix, check the format */
> +	if (desc->type == TRACEFS_DYNEVENT_UPROBE || desc->type == TRACEFS_DYNEVENT_URETPROBE) {

Since the above is now bitmasks, you can change it to:

	if (desc->type & (TRACEFS_DYNEVENT_UPROBE | TRACEFS_DYNEVENT_URETPROBE))


> +		if (!strchr(address, '/'))
> +			return -1;
> +	}
> +
> +	if (group && (!system || strcmp(group, system) != 0))
> +		return -1;
> +
> +	if (!ret_dyn)
> +		return 0;
> +
> +	dyn = calloc(1, sizeof(*dyn));
> +	if (!dyn)
> +		return -1;
> +
> +	dyn->type = desc->type;
> +	dyn->trace_file = strdup(desc->file);
> +	if (!dyn->trace_file)
> +		goto error;
> +
> +	dyn->prefix = strdup(prefix);
> +	if (!dyn->prefix)
> +		goto error;
> +
> +	if (system) {
> +		dyn->system = strdup(system);
> +		if (!dyn->system)
> +			goto error;
> +	}
> +
> +	if (event) {
> +		dyn->event = strdup(event);
> +		if (!dyn->event)
> +			goto error;
> +	}
> +
> +	if (address) {
> +		dyn->address = strdup(address);
> +		if (!dyn->address)
> +			goto error;
> +

I know I mentioned that errors should have a empty line after them, but
that's only if there's another command after it. It doesn't apply to end of
blocks.

> +	}
> +
> +	if (format) {
> +		dyn->format = strdup(format);
> +		if (!dyn->format)
> +			goto error;
> +

Same here.

> +	}
> +
> +	*ret_dyn = dyn;
> +	return 0;
> +error:
> +	tracefs_dynevent_free(dyn);
> +	return -1;
> +}
> +
> +static int dyn_synth_del(struct dyn_events_desc *desc, struct tracefs_dynevent *dyn)
> +{
> +	char *str;
> +	int ret;
> +
> +	if (strcmp(desc->file, DYNEVENTS_EVENTS))
> +		return dyn_generic_del(desc, dyn);
> +
> +	ret = asprintf(&str, "!%s", dyn->event);
> +	if (ret < 0)
> +		return -1;
> +
> +	ret = tracefs_instance_file_append(NULL, desc->file, str);
> +	free(str);
> +
> +	return ret < 0 ? ret : 0;
> +}
> +
> +/*
> + * Parse lines from synthetic_events file
> + * EVENT ARG [ARG]
> + */
> +static int dyn_synth_parse(struct dyn_events_desc *desc, const char *group,
> +			   char *line, struct tracefs_dynevent **ret_dyn)
> +{
> +	struct tracefs_dynevent *dyn;
> +	char *format;
> +	char *event;
> +	char *sav;
> +
> +	if (strcmp(desc->file, DYNEVENTS_EVENTS))
> +		return dyn_generic_parse(desc, group, line, ret_dyn);
> +
> +	/* synthetic_events file has slightly different syntax */
> +	event = strtok_r(line, " ", &sav);
> +	if (!event || *event == '\0')
> +		return -1;
> +
> +	format = strtok_r(NULL, "", &sav);
> +	if (!format || *format == '\0')
> +		return -1;
> +
> +	if (!ret_dyn)
> +		return 0;
> +
> +	dyn = calloc(1, sizeof(*dyn));
> +	if (!dyn)
> +		return -1;
> +
> +	dyn->type = desc->type;
> +	dyn->trace_file = strdup(desc->file);
> +	if (!dyn->trace_file)
> +		goto error;
> +
> +	dyn->event = strdup(event);
> +	if (!dyn->event)
> +		goto error;
> +
> +	dyn->format = strdup(format+1);
> +	if (!dyn->format)
> +		goto error;
> +
> +	*ret_dyn = dyn;
> +	return 0;
> +error:
> +	tracefs_dynevent_free(dyn);
> +	return -1;
> +}
> +
> +static void init_devent_desc(void)
> +{
> +	int max = bit_index(TRACEFS_DYNEVENT_MAX);
> +	int i;
> +
> +	BUILD_BUG_ON(ARRAY_SIZE(dynevents) != max);
> +
> +	/* Use  ftrace dynamic_events, if available */
> +	if (tracefs_file_exists(NULL, DYNEVENTS_EVENTS)) {
> +		for (i = 0; i < max; i++)
> +			dynevents[i].file = DYNEVENTS_EVENTS;
> +		return;
> +	}
> +
> +	if (tracefs_file_exists(NULL, KPROBE_EVENTS)) {
> +		dynevents[bit_index(TRACEFS_DYNEVENT_KPROBE)].file = KPROBE_EVENTS;
> +		dynevents[bit_index(TRACEFS_DYNEVENT_KRETPROBE)].file = KPROBE_EVENTS;
> +	}
> +	if (tracefs_file_exists(NULL, UPROBE_EVENTS)) {
> +		dynevents[bit_index(TRACEFS_DYNEVENT_UPROBE)].file = UPROBE_EVENTS;
> +		dynevents[bit_index(TRACEFS_DYNEVENT_URETPROBE)].file = UPROBE_EVENTS;
> +	}
> +	if (tracefs_file_exists(NULL, SYNTH_EVENTS)) {
> +		dynevents[bit_index(TRACEFS_DYNEVENT_SYNTH)].file = SYNTH_EVENTS;
> +		dynevents[bit_index(TRACEFS_DYNEVENT_SYNTH)].prefix = "";
> +	}
> +
> +}
> +
> +static struct dyn_events_desc *get_devent_desc(int index)
> +{
> +	static bool init;
> +	static int max;
> +
> +	if (index < 0)
> +		return NULL;
> +
> +	if (!init) {
> +		init_devent_desc();
> +		max = bit_index(TRACEFS_DYNEVENT_MAX);
> +		init = true;
> +	}
> +
> +	if (index < 0 || index >= max)
> +		return NULL;
> +
> +	return &dynevents[index];
> +}
> +
> +/**
> + * dynevent_alloc - Allocate new dynamic event
> + * @type: Type of the dynamic event
> + * @system: The system name (NULL for the default dynamic)
> + * @event: Name of the event
> + * @addr: The function and offset (or address) to insert the probe
> + * @format: The format string to define the probe.
> + *
> + * Allocate a dynamic event context that will be in the @system group
> + * (or dynamic if @system is NULL). Have the name of @event and
> + * will be associated to @addr, if applicable for that event type
> + * (function name, with or without offset, or a address). And the @format will
> + * define the format of the kprobe.
> + * The dynamic event is not created in the system.
> + *
> + * Return a pointer to a dynamic event context on success, or NULL on error.
> + * The returned pointer must be freed with tracefs_dynevent_free()
> + *
> + * errno will be set to EINVAL if event is NULL.
> + */
> +__hidden struct tracefs_dynevent *
> +dynevent_alloc(enum tracefs_dynevent_type type, const char *system,
> +	       const char *event, const char *address, const char *format)
> +{
> +	struct tracefs_dynevent *devent;
> +	struct dyn_events_desc *desc;
> +
> +	if (!event) {
> +		errno = EINVAL;
> +		return NULL;
> +	}
> +
> +	desc = get_devent_desc(bit_index(type));
> +	if (!desc || !desc->file) {
> +		errno = ENOTSUP;
> +		return NULL;
> +	}
> +
> +	devent = calloc(1, sizeof(*devent));
> +	if (!devent)
> +		return NULL;
> +
> +	devent->type = type;
> +	devent->trace_file = strdup(desc->file);
> +	if (!devent->trace_file)
> +		goto err;
> +
> +	if (!system)
> +		system = DYNEVENTS_DEFAULT_GROUP;
> +	devent->system = strdup(system);
> +	if (!devent->system)
> +		goto err;
> +
> +	devent->event = strdup(event);
> +	if (!devent->event)
> +		goto err;
> +
> +	devent->prefix = strdup(desc->prefix);
> +	if (!devent->prefix)
> +		goto err;
> +
> +	if (address) {
> +		devent->address = strdup(address);
> +		if (!devent->address)
> +			goto err;
> +	}
> +	if (format) {
> +		devent->format = strdup(format);
> +		if (!devent->format)
> +			goto err;
> +	}
> +
> +	return devent;
> +err:
> +	tracefs_dynevent_free(devent);
> +	return NULL;
> +}
> +
> +/**
> + * tracefs_dynevent_create - Create a dynamic event in the system
> + * @devent: Pointer to a dynamic event context, describing the event
> + *
> + * Return 0 on success, or -1 on error.
> + */
> +int tracefs_dynevent_create(struct tracefs_dynevent *devent)
> +{
> +	char *str;
> +	int ret;
> +
> +	if (!devent)
> +		return -1;
> +
> +	if (devent->system && devent->system[0])
> +		ret = asprintf(&str, "%s%s%s/%s %s %s\n",
> +				devent->prefix, strlen(devent->prefix) ? ":" : "",
> +				devent->system, devent->event,
> +				devent->address ? devent->address : "",
> +				devent->format ? devent->format : "");
> +	else
> +		ret = asprintf(&str, "%s%s%s %s %s\n",
> +				devent->prefix, strlen(devent->prefix) ? ":" : "",
> +				devent->event,
> +				devent->address ? devent->address : "",
> +				devent->format ? devent->format : "");
> +	if (ret < 0)
> +		return -1;
> +
> +	ret = tracefs_instance_file_append(NULL, devent->trace_file, str);
> +	free(str);
> +
> +	return ret < 0 ? ret : 0;
> +}
> +
> +static void disable_events(const char *system, const char *event,
> +			   char **list)
> +{
> +	struct tracefs_instance *instance;
> +	int i;
> +
> +	/*
> +	 * Note, this will not fail even on error.
> +	 * That is because even if something fails, it may still
> +	 * work enough to clear the kprobes. If that's the case
> +	 * the clearing after the loop will succeed and the function
> +	 * is a success, even though other parts had failed. If
> +	 * one of the kprobe events is enabled in one of the
> +	 * instances that fail, then the clearing will fail too
> +	 * and the function will return an error.
> +	 */
> +
> +	tracefs_event_disable(NULL, system, event);
> +	/* No need to test results */
> +
> +	if (!list)
> +		return;
> +
> +	for (i = 0; list[i]; i++) {
> +		instance = tracefs_instance_alloc(NULL, list[i]);
> +		/* If this fails, try the next one */
> +		if (!instance)
> +			continue;
> +		tracefs_event_disable(instance, system, event);
> +		tracefs_instance_free(instance);
> +	}
> +}
> +
> +/**
> + * tracefs_dynevent_destroy - Remove a dynamic event from the system
> + * @devent: A dynamic event context, describing the dynamic event that will be deleted.
> + * @force: Will attempt to disable all events before removing them.
> + *
> + * The dynamic event context is not freed by this API. It only removes the event from the system.
> + * If there are any enabled events, and @force is not set, then it will error with -1 and errno
> + * to be EBUSY.
> + *
> + * Return 0 on success, or -1 on error.
> + */
> +int tracefs_dynevent_destroy(struct tracefs_dynevent *devent, bool force)
> +{
> +	struct dyn_events_desc *desc;
> +	char **instance_list;
> +
> +	if (!devent)
> +		return -1;
> +
> +	if (force) {
> +		instance_list = tracefs_instances(NULL);
> +		disable_events(devent->system, devent->event, instance_list);
> +		tracefs_list_free(instance_list);
> +	}
> +
> +	desc = get_devent_desc(bit_index(devent->type));
> +	if (!desc)
> +		return -1;
> +
> +	return desc->del(desc, devent);
> +}
> +
> +static int get_all_dynevents(int index, const char *system,
> +			     struct tracefs_dynevent ***ret_all)
> +{
> +	struct dyn_events_desc *desc;
> +	struct tracefs_dynevent *devent, **tmp, **all = NULL;
> +	char *content;
> +	int count = 0;
> +	char *line;
> +	char *next;
> +	int ret;
> +
> +	desc = get_devent_desc(index);
> +	if (!desc)
> +		return -1;
> +
> +	content = tracefs_instance_file_read(NULL, desc->file, NULL);
> +	if (!content)
> +		return -1;
> +
> +	line = content;
> +	do {
> +		next = strchr(line, '\n');
> +		if (next)
> +			*next = '\0';
> +		ret = desc->parse(desc, system, line, ret_all ? &devent : NULL);
> +		if (!ret) {
> +			if (ret_all) {
> +				tmp = realloc(all, (count + 1) * sizeof(*tmp));
> +				if (!tmp)
> +					goto error;
> +				all = tmp;
> +				all[count] = devent;
> +			}
> +			count++;
> +		}
> +		line = next + 1;
> +	} while (next);
> +
> +	free(content);
> +	if (ret_all)
> +		*ret_all = all;
> +	return count;
> +
> +error:
> +	free(content);
> +	free(all);
> +	return -1;
> +}
> +
> +/**
> + * tracefs_dynevent_list_free - Deletes an array of pointers to dynamic event contexts
> + * @events: An array of pointers to dynamic event contexts. The last element of the array
> + *	    must be a NULL pointer.
> + */
> +void tracefs_dynevent_list_free(struct tracefs_dynevent **events)
> +{
> +	int i = 0;
> +
> +	if (!events)
> +		return;
> +
> +	while (events[i])

A for loop is safer. As this adds an unneeded dependency between the loop
and the below command. As well as requires initializing i above. Three
dependent actions in three different locations is not robust.

	for (i = 0; events[i]; i++)

is condensed and safer to modifications of the code.

> +		tracefs_dynevent_free(events[i++]);
> +
> +	free(events);
> +}
> +
> +/**
> + * tracefs_dynevent_get_all - return an array of pointers to dynamic events of given types
> + * @types: Dynamic event type, or bitmask of dynamic event types. If 0 is passed, all types
> + *	   are considered.
> + * @system: Get events from that system only. If @system is NULL, events from all systems
> + *	    are returned.
> + *
> + * Returns an array of pointers to dynamic events of given types that exist in the system.
> + * The array must be freed with tracefs_dynevent_list_free(). If there are no events a NULL
> + * pointer is returned.
> + */
> +struct tracefs_dynevent **
> +tracefs_dynevent_get_all(enum tracefs_dynevent_type types, const char *system)

As mentioned above, types is not of type enum tracefs_dynevent_type and
should not be declared that way.

-- Steve

> +{
> +	struct tracefs_dynevent **events, **tmp, **all_events = NULL;
> +	int count, all = 0;
> +	int i;
> +
> +	for (i = 1; i < TRACEFS_DYNEVENT_MAX; i <<= 1) {
> +		if (types) {
> +			if (i > types)
> +				break;
> +			if (!(types & i))
> +				continue;
> +		}
> +		count = get_all_dynevents(i - 1, system, &events);
> +		if (count > 0) {
> +			tmp = realloc(all_events, (all + count + 1) * sizeof(*tmp));
> +			if (!tmp)
> +				goto error;
> +			all_events = tmp;
> +			memcpy(all_events + all, events, count * sizeof(*events));
> +			all += count;
> +			/* Add a NULL pointer at the end */
> +			all_events[all] = NULL;
> +		}
> +	}
> +
> +	return all_events;
> +
> +error:
> +	if (all_events) {
> +		for (i = 0; i < all; i++)
> +			free(all_events[i]);
> +		free(all_events);
> +	}
> +	return NULL;
> +}
> +
> +/**
> + * tracefs_dynevent_destroy_all - removes all dynamic events of given types from the system
> + * @types: Dynamic event type, or bitmask of dynamic event types. If 0 is passed, all types
> + *	   are considered.
> + * @force: Will attempt to disable all events before removing them.
> + *
> + * Will remove all dynamic events of the given types from the system. If there are any enabled
> + * events, and @force is not set, then the removal of these will fail. If @force is set, then
> + * it will attempt to disable all the events in all instances before removing them.
> + *
> + * Returns zero if all requested events are removed successfully, or -1 if some of them are not
> + * removed.
> + */
> +int tracefs_dynevent_destroy_all(enum tracefs_dynevent_type types, bool force)
> +{
> +	struct tracefs_dynevent **all;
> +	int ret = 0;
> +	int i;
> +
> +	all = tracefs_dynevent_get_all(types, NULL);
> +	if (!all)
> +		return 0;
> +
> +	for (i = 0; all[i]; i++) {
> +		if (tracefs_dynevent_destroy(all[i], force))
> +			ret = -1;
> +	}
> +
> +	tracefs_dynevent_list_free(all);
> +
> +	return ret;
> +}
> +
> +/**
> + * dynevent_get_count - Count dynamic events of given types and system
> + * @types: Dynamic event type, or bitmask of dynamic event types. If 0 is passed, all types
> + *	   are considered.
> + * @system: Count events from that system only. If @system is NULL, events from all systems
> + *	    are counted.
> + *
> + * Return the count of requested dynamic events
> + */
> +__hidden int dynevent_get_count(enum tracefs_dynevent_type types, const char *system)
> +{
> +	int count, all = 0;
> +	int i;
> +
> +	for (i = 1; i < TRACEFS_DYNEVENT_MAX; i <<= 1) {
> +		if (types) {
> +			if (i > types)
> +				break;
> +			if (!(types & i))
> +				continue;
> +		}
> +		count = get_all_dynevents(i - 1, system, NULL);
> +		if (count > 0)
> +			all += count;
> +	}
> +
> +	return all;
> +}

Re: [PATCH v4 01/10] libtracefs: New APIs for dynamic events

[Steven Rostedt]

On Thu,  4 Nov 2021 13:10:38 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> +static void init_devent_desc(void)
> +{
> +	int max = bit_index(TRACEFS_DYNEVENT_MAX);
> +	int i;
> +
> +	BUILD_BUG_ON(ARRAY_SIZE(dynevents) != max);
> +
> +	/* Use  ftrace dynamic_events, if available */
> +	if (tracefs_file_exists(NULL, DYNEVENTS_EVENTS)) {
> +		for (i = 0; i < max; i++)
> +			dynevents[i].file = DYNEVENTS_EVENTS;
> +		return;
> +	}
> +
> +	if (tracefs_file_exists(NULL, KPROBE_EVENTS)) {
> +		dynevents[bit_index(TRACEFS_DYNEVENT_KPROBE)].file = KPROBE_EVENTS;
> +		dynevents[bit_index(TRACEFS_DYNEVENT_KRETPROBE)].file = KPROBE_EVENTS;
> +	}
> +	if (tracefs_file_exists(NULL, UPROBE_EVENTS)) {
> +		dynevents[bit_index(TRACEFS_DYNEVENT_UPROBE)].file = UPROBE_EVENTS;
> +		dynevents[bit_index(TRACEFS_DYNEVENT_URETPROBE)].file = UPROBE_EVENTS;
> +	}
> +	if (tracefs_file_exists(NULL, SYNTH_EVENTS)) {
> +		dynevents[bit_index(TRACEFS_DYNEVENT_SYNTH)].file = SYNTH_EVENTS;
> +		dynevents[bit_index(TRACEFS_DYNEVENT_SYNTH)].prefix = "";
> +	}
> +

Nit. Remove the extra line.

-- Steve

> +}
> +

Re: [PATCH v4 01/10] libtracefs: New APIs for dynamic events

[Steven Rostedt]

On Thu,  4 Nov 2021 13:10:38 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:


>  
> +/* Dynamic events */
> +struct tracefs_dynevent;
> +enum tracefs_dynevent_type {
> +	TRACEFS_DYNEVENT_KPROBE		= 1 << 0,
> +	TRACEFS_DYNEVENT_KRETPROBE	= 1 << 1,
> +	TRACEFS_DYNEVENT_UPROBE		= 1 << 2,
> +	TRACEFS_DYNEVENT_URETPROBE	= 1 << 3,
> +	TRACEFS_DYNEVENT_EPROBE		= 1 << 4,
> +	TRACEFS_DYNEVENT_SYNTH		= 1 << 5,
> +	TRACEFS_DYNEVENT_MAX		= 1 << 6,
> +};

[..]

> +
> +static struct dyn_events_desc *get_devent_desc(int index)

This should take the enum tracefs_dynevent_type.

> +{
> +	static bool init;
> +	static int max;

Why the max variable? It's always set to a constant defined at compile time.

> +
> +	if (index < 0)
> +		return NULL;

This should never happen as this is a static function, and is not needed if
we take the enum as the argument.

> +
> +	if (!init) {
> +		init_devent_desc();
> +		max = bit_index(TRACEFS_DYNEVENT_MAX);
> +		init = true;
> +	}
> +

Here we can have the bit_index:

	/* One bit has to be set */
	if (!index)
		return NULL;

And since we only expect one bit set, we can have:

	/* Only one bit must be set */
	if (index & (index - 1))
		return NULL;

Because the above is true iff index is not a power of two.

Since now we know that index has only a single bit set, we can compare to
max:

	/* Is it a valid value? */
	if (index >= TRACEFS_DYNEVENT_MAX)
		return NULL;

Then we use bit_index here:

	return &dynevents[bit_index(index)];

And remove having to use bit_index in the below callers.

> +	if (index < 0 || index >= max)
> +		return NULL;
> +
> +	return &dynevents[index];
> +}
> +
> +/**
> + * dynevent_alloc - Allocate new dynamic event
> + * @type: Type of the dynamic event
> + * @system: The system name (NULL for the default dynamic)
> + * @event: Name of the event
> + * @addr: The function and offset (or address) to insert the probe
> + * @format: The format string to define the probe.
> + *
> + * Allocate a dynamic event context that will be in the @system group
> + * (or dynamic if @system is NULL). Have the name of @event and
> + * will be associated to @addr, if applicable for that event type
> + * (function name, with or without offset, or a address). And the @format will
> + * define the format of the kprobe.
> + * The dynamic event is not created in the system.
> + *
> + * Return a pointer to a dynamic event context on success, or NULL on error.
> + * The returned pointer must be freed with tracefs_dynevent_free()
> + *
> + * errno will be set to EINVAL if event is NULL.
> + */
> +__hidden struct tracefs_dynevent *
> +dynevent_alloc(enum tracefs_dynevent_type type, const char *system,
> +	       const char *event, const char *address, const char *format)
> +{
> +	struct tracefs_dynevent *devent;
> +	struct dyn_events_desc *desc;
> +
> +	if (!event) {
> +		errno = EINVAL;
> +		return NULL;
> +	}
> +
> +	desc = get_devent_desc(bit_index(type));

	desc = get_devent_desc(type);

> +	if (!desc || !desc->file) {
> +		errno = ENOTSUP;
> +		return NULL;
> +	}
> +
> +	devent = calloc(1, sizeof(*devent));
> +	if (!devent)
> +		return NULL;
> +
> +	devent->type = type;
> +	devent->trace_file = strdup(desc->file);
> +	if (!devent->trace_file)
> +		goto err;
> +
> +	if (!system)
> +		system = DYNEVENTS_DEFAULT_GROUP;
> +	devent->system = strdup(system);
> +	if (!devent->system)
> +		goto err;
> +
> +	devent->event = strdup(event);
> +	if (!devent->event)
> +		goto err;
> +
> +	devent->prefix = strdup(desc->prefix);
> +	if (!devent->prefix)
> +		goto err;
> +
> +	if (address) {
> +		devent->address = strdup(address);
> +		if (!devent->address)
> +			goto err;
> +	}
> +	if (format) {
> +		devent->format = strdup(format);
> +		if (!devent->format)
> +			goto err;
> +	}
> +
> +	return devent;
> +err:
> +	tracefs_dynevent_free(devent);
> +	return NULL;
> +}
> +



> +/**
> + * tracefs_dynevent_destroy - Remove a dynamic event from the system
> + * @devent: A dynamic event context, describing the dynamic event that will be deleted.
> + * @force: Will attempt to disable all events before removing them.
> + *
> + * The dynamic event context is not freed by this API. It only removes the event from the system.
> + * If there are any enabled events, and @force is not set, then it will error with -1 and errno
> + * to be EBUSY.
> + *
> + * Return 0 on success, or -1 on error.
> + */
> +int tracefs_dynevent_destroy(struct tracefs_dynevent *devent, bool force)
> +{
> +	struct dyn_events_desc *desc;
> +	char **instance_list;
> +
> +	if (!devent)
> +		return -1;
> +
> +	if (force) {
> +		instance_list = tracefs_instances(NULL);
> +		disable_events(devent->system, devent->event, instance_list);
> +		tracefs_list_free(instance_list);
> +	}
> +
> +	desc = get_devent_desc(bit_index(devent->type));

	desc = get_devent_desc(devent->type);

> +	if (!desc)
> +		return -1;
> +
> +	return desc->del(desc, devent);
> +}
> +
> +static int get_all_dynevents(int index, const char *system,
> +			     struct tracefs_dynevent ***ret_all)

This too should be passed in the enum, because you changed the caller to
it below, where you are passing in the mask and not the index.

> +{
> +	struct dyn_events_desc *desc;
> +	struct tracefs_dynevent *devent, **tmp, **all = NULL;
> +	char *content;
> +	int count = 0;
> +	char *line;
> +	char *next;
> +	int ret;
> +
> +	desc = get_devent_desc(index);
> +	if (!desc)
> +		return -1;
> +
> +	content = tracefs_instance_file_read(NULL, desc->file, NULL);
> +	if (!content)
> +		return -1;
> +
> +	line = content;
> +	do {
> +		next = strchr(line, '\n');
> +		if (next)
> +			*next = '\0';
> +		ret = desc->parse(desc, system, line, ret_all ? &devent : NULL);
> +		if (!ret) {
> +			if (ret_all) {
> +				tmp = realloc(all, (count + 1) * sizeof(*tmp));
> +				if (!tmp)
> +					goto error;
> +				all = tmp;
> +				all[count] = devent;
> +			}
> +			count++;
> +		}
> +		line = next + 1;
> +	} while (next);
> +
> +	free(content);
> +	if (ret_all)
> +		*ret_all = all;
> +	return count;
> +
> +error:
> +	free(content);
> +	free(all);
> +	return -1;
> +}
> +

> +
> +/**
> + * tracefs_dynevent_get_all - return an array of pointers to dynamic events of given types
> + * @types: Dynamic event type, or bitmask of dynamic event types. If 0 is passed, all types
> + *	   are considered.
> + * @system: Get events from that system only. If @system is NULL, events from all systems
> + *	    are returned.
> + *
> + * Returns an array of pointers to dynamic events of given types that exist in the system.
> + * The array must be freed with tracefs_dynevent_list_free(). If there are no events a NULL
> + * pointer is returned.
> + */
> +struct tracefs_dynevent **
> +tracefs_dynevent_get_all(enum tracefs_dynevent_type types, const char *system)
> +{
> +	struct tracefs_dynevent **events, **tmp, **all_events = NULL;
> +	int count, all = 0;
> +	int i;
> +
> +	for (i = 1; i < TRACEFS_DYNEVENT_MAX; i <<= 1) {
> +		if (types) {
> +			if (i > types)
> +				break;
> +			if (!(types & i))
> +				continue;
> +		}
> +		count = get_all_dynevents(i - 1, system, &events);

I'm confused at what you are trying to do above. As i is the bitmask, and
you are calling get_all_dynevents for all types below it, and doing it for
each mask? I think you want to just pass in i, as  that's the bitmask you
want.


> +		if (count > 0) {
> +			tmp = realloc(all_events, (all + count + 1) * sizeof(*tmp));
> +			if (!tmp)
> +				goto error;
> +			all_events = tmp;
> +			memcpy(all_events + all, events, count * sizeof(*events));
> +			all += count;
> +			/* Add a NULL pointer at the end */
> +			all_events[all] = NULL;
> +		}
> +	}
> +
> +	return all_events;
> +
> +error:
> +	if (all_events) {
> +		for (i = 0; i < all; i++)
> +			free(all_events[i]);
> +		free(all_events);
> +	}
> +	return NULL;
> +}
> +
> +/**
> + * tracefs_dynevent_destroy_all - removes all dynamic events of given types from the system
> + * @types: Dynamic event type, or bitmask of dynamic event types. If 0 is passed, all types
> + *	   are considered.
> + * @force: Will attempt to disable all events before removing them.
> + *
> + * Will remove all dynamic events of the given types from the system. If there are any enabled
> + * events, and @force is not set, then the removal of these will fail. If @force is set, then
> + * it will attempt to disable all the events in all instances before removing them.
> + *
> + * Returns zero if all requested events are removed successfully, or -1 if some of them are not
> + * removed.
> + */
> +int tracefs_dynevent_destroy_all(enum tracefs_dynevent_type types, bool force)

This too needs to be an int, and not the enum, because more than one type
is no longer a valid enum tracefs_dynevent_type.


> +{
> +	struct tracefs_dynevent **all;
> +	int ret = 0;
> +	int i;
> +
> +	all = tracefs_dynevent_get_all(types, NULL);
> +	if (!all)
> +		return 0;
> +
> +	for (i = 0; all[i]; i++) {
> +		if (tracefs_dynevent_destroy(all[i], force))
> +			ret = -1;
> +	}
> +
> +	tracefs_dynevent_list_free(all);
> +
> +	return ret;
> +}
> +
> +/**
> + * dynevent_get_count - Count dynamic events of given types and system
> + * @types: Dynamic event type, or bitmask of dynamic event types. If 0 is passed, all types
> + *	   are considered.
> + * @system: Count events from that system only. If @system is NULL, events from all systems
> + *	    are counted.
> + *
> + * Return the count of requested dynamic events
> + */
> +__hidden int dynevent_get_count(enum tracefs_dynevent_type types, const char *system)
> +{
> +	int count, all = 0;
> +	int i;
> +
> +	for (i = 1; i < TRACEFS_DYNEVENT_MAX; i <<= 1) {
> +		if (types) {
> +			if (i > types)
> +				break;
> +			if (!(types & i))
> +				continue;
> +		}
> +		count = get_all_dynevents(i - 1, system, NULL);

Same here.

-- Steve

> +		if (count > 0)
> +			all += count;
> +	}
> +
> +	return all;
> +}

Re: [PATCH v4 02/10] libtracefs: New APIs for kprobe allocation

[Steven Rostedt]

On Thu,  4 Nov 2021 13:10:39 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> +tracefs_kretprobe_alloc(const char *system, const char *event,
> +			const char *addr, const char *format, int max);

Probably should be "unsigned int max"

-- Steve

Re: [PATCH v4 04/10] libtracefs: Change tracefs_kprobe_info API

[Steven Rostedt]

On Thu,  4 Nov 2021 13:10:41 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> +enum tracefs_dynevent_type tracefs_kprobe_info(struct tracefs_dynevent *kprobe,
> +					       char **system, char **event,
> +					       char **prefix, char **addr, char **format)
> +{
> +	char **lv[] = { system, event, prefix, addr, format };
> +	char **rv[] = { &kprobe->system, &kprobe->event, &kprobe->prefix,
> +			&kprobe->address, &kprobe->format };
> +	int i;
> +
> +	if (!kprobe)
> +		return TRACEFS_DYNEVENT_MAX;
> +
> +	for (i = 0; i < ARRAY_SIZE(lv); i++)
> +		*lv[i] = NULL;

Do we really need to initialize them to NULL here?

Not to mention, if one of the parameters is NULL itself, this will SEGFAULT.

> +
> +	for (i = 0; i < ARRAY_SIZE(lv); i++) {

Nice use of ARRAY_SIZE() ;-)

> +		if (lv[i]) {
> +			if (*rv[i]) {
> +				*lv[i] = strdup(*rv[i]);
> +				if (!*lv[i])
> +					goto error;
> +			} else {
> +				*lv[i] = NULL;
>  			}

The above here sets it to NULL if the parameter is non NULL.

We don't need the initial NULL setting loop.

-- Steve


> -			break;
>  		}
> -		ret = parse_kprobe(NULL, &saveptr, &ktype, &system, &probe,
> -				   &kaddr, &kfmt);
>  	}
> -	free(content);
> -	return rtype;
> +
> +	return kprobe->type;
> +
> +error:
> +	for (i--; i >= 0; i--) {
> +		if (lv[i])
> +			free(*lv[i]);
> +	}
> +
> +	return TRACEFS_DYNEVENT_MAX;
>  }

Re: [PATCH v4 08/10] libtracefs: Use the internal dynamic events API when creating synthetic events

[Steven Rostedt]

On Thu,  4 Nov 2021 13:10:45 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> Synthetic events are type of ftrace dynamic events. The tracefs library
> has dedicated APIs to manage dynamic events of all types. In order the
> code to be consistent, the creation of synthetic events inside the
> library is reimplemented with these new dynamic events APIs.
> 
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> ---
>  src/tracefs-hist.c | 103 +++++++++++++++++++++------------------------
>  1 file changed, 47 insertions(+), 56 deletions(-)
> 
> diff --git a/src/tracefs-hist.c b/src/tracefs-hist.c
> index 9009dba..08bb2da 100644
> --- a/src/tracefs-hist.c
> +++ b/src/tracefs-hist.c
> @@ -661,6 +661,7 @@ struct tracefs_synth {
>  	struct tep_event	*end_event;
>  	struct action		*actions;
>  	struct action		**next_action;
> +	struct tracefs_dynevent	*dyn_event;
>  	char			*name;
>  	char			**synthetic_fields;
>  	char			**synthetic_args;
> @@ -719,6 +720,7 @@ void tracefs_synth_free(struct tracefs_synth *synth)
>  		synth->actions = action->next;
>  		action_free(action);
>  	}
> +	tracefs_dynevent_free(synth->dyn_event);
>  
>  	free(synth);
>  }
> @@ -889,6 +891,28 @@ synth_init_from(struct tep_handle *tep, const char *start_system,
>  	return synth;
>  }
>  
> +static int alloc_synthetic_event(struct tracefs_synth *synth)
> +{
> +	char *synthetic_format;

Should we just call it "format". It's obviously for the synthetic event.

> +	const char *field;
> +	int i;
> +
> +	synthetic_format = strdup("");
> +	if (!synthetic_format)
> +		return -1;
> +
> +	for (i = 0; synth->synthetic_fields && synth->synthetic_fields[i]; i++) {
> +		field = synth->synthetic_fields[i];
> +		synthetic_format = append_string(synthetic_format, " ", field);

My OCD is bothering me that the first field has a space appended to it.

		format = append_string(format, i ? " " : NULL, field);


> +	}
> +
> +	synth->dyn_event = dynevent_alloc(TRACEFS_DYNEVENT_SYNTH, NULL,
> +					  synth->name, NULL, synthetic_format);
> +	free(synthetic_format);
> +
> +	return synth->dyn_event ? 0 : -1;
> +}
> +
>  /**
>   * tracefs_synth_alloc - create a new tracefs_synth instance
>   * @tep: The tep handle that holds the events to work on
> @@ -1609,38 +1633,6 @@ int tracefs_synth_save(struct tracefs_synth *synth,
>  	return 0;
>  }
>  
> -static char *create_synthetic_event(struct tracefs_synth *synth)
> -{
> -	char *synthetic_event;
> -	const char *field;
> -	int i;
> -
> -	synthetic_event = strdup(synth->name);
> -	if (!synthetic_event)
> -		return NULL;
> -
> -	for (i = 0; synth->synthetic_fields && synth->synthetic_fields[i]; i++) {
> -		field = synth->synthetic_fields[i];
> -		synthetic_event = append_string(synthetic_event, " ", field);
> -	}
> -
> -	return synthetic_event;
> -}
> -
> -static int remove_synthetic(const char *synthetic)
> -{
> -	char *str;
> -	int ret;
> -
> -	ret = asprintf(&str, "!%s", synthetic);
> -	if (ret < 0)
> -		return -1;
> -
> -	ret = tracefs_instance_file_append(NULL, "synthetic_events", str);
> -	free(str);
> -	return ret < 0 ? -1 : 0;
> -}
> -
>  static int remove_hist(struct tracefs_instance *instance,
>  		       struct tep_event *event, const char *hist)
>  {
> @@ -1919,7 +1911,6 @@ tracefs_synth_get_start_hist(struct tracefs_synth *synth)
>  int tracefs_synth_create(struct tracefs_instance *instance,
>  			 struct tracefs_synth *synth)

I think we should call this:

	tracefs_synth_create_raw()

that passes in the "instance".

Then we could have tracefs_synth_create() just use the top instance (no
instance passed to it), and we could decide later if we want to create an
internal instance or not to do the work to keep from modifying the top
instance.

That is, we would have:

int tracefs_synth_create(struct tracefs_synth *synth)
{
	return tracefs_synth_create_raw(synth->create_instance, synth);
}

Have synth->create_instance be defaulted to NULL on allocation, and would
get updated by another interface perhaps?

We could also add to the _raw() function:

	if (synth->create_instance && instance &&
	    synth->create_instance != instance) {
		errno = EINVAL;
		return -1
	}

	if (!synth->create_instance && instance) {
		syth->create_instance = instance;
		trace_get_instance(instance);
	}

Would need to have in the destructor:

	if (synth->create_instance)
		trace_put_instance(synth->create_instance);


Or something like that.


>  {
> -	char *synthetic_event;
>  	char *start_hist = NULL;
>  	char *end_hist = NULL;
>  	int ret;
> @@ -1937,14 +1928,10 @@ int tracefs_synth_create(struct tracefs_instance *instance,
>  	if (verify_state(synth) < 0)
>  		return -1;
>  
> -	synthetic_event = create_synthetic_event(synth);
> -	if (!synthetic_event)
> +	if (!synth->dyn_event && alloc_synthetic_event(synth))
> +		return -1;
> +	if (!tracefs_dynevent_create(synth->dyn_event))
>  		return -1;
> -
> -	ret = tracefs_instance_file_append(NULL, "synthetic_events",
> -					   synthetic_event);
> -	if (ret < 0)
> -		goto free_synthetic;
>  
>  	start_hist = create_hist(synth->start_keys, synth->start_vars);
>  	start_hist = append_filter(start_hist, synth->start_filter,
> @@ -1980,9 +1967,7 @@ int tracefs_synth_create(struct tracefs_instance *instance,
>   remove_synthetic:
>  	free(end_hist);
>  	free(start_hist);
> -	remove_synthetic(synthetic_event);
> - free_synthetic:
> -	free(synthetic_event);
> +	tracefs_dynevent_destroy(synth->dyn_event, false);
>  	return -1;
>  }
>  
> @@ -2007,7 +1992,6 @@ int tracefs_synth_create(struct tracefs_instance *instance,
>  int tracefs_synth_destroy(struct tracefs_instance *instance,
>  			  struct tracefs_synth *synth)
>  {
> -	char *synthetic_event;
>  	char *hist;
>  	int ret;
>  
> @@ -2041,11 +2025,7 @@ int tracefs_synth_destroy(struct tracefs_instance *instance,
>  	ret = remove_hist(instance, synth->start_event, hist);
>  	free(hist);
>  
> -	synthetic_event = create_synthetic_event(synth);
> -	if (!synthetic_event)
> -		return -1;
> -
> -	ret = remove_synthetic(synthetic_event);
> +	ret = tracefs_dynevent_destroy(synth->dyn_event, false);
>  
>  	return ret ? -1 : 0;
>  }
> @@ -2067,7 +2047,7 @@ int tracefs_synth_show(struct trace_seq *seq,
>  		       struct tracefs_instance *instance,
>  		       struct tracefs_synth *synth)
>  {
> -	char *synthetic_event = NULL;
> +	bool new_event = false;
>  	char *hist = NULL;
>  	char *path;
>  	int ret = -1;
> @@ -2082,16 +2062,19 @@ int tracefs_synth_show(struct trace_seq *seq,
>  		return -1;
>  	}
>  
> -	synthetic_event = create_synthetic_event(synth);
> -	if (!synthetic_event)
> -		return -1;
> +	if (!synth->dyn_event) {
> +		if (alloc_synthetic_event(synth))
> +			return -1;
> +		new_event = true;
> +	}

We should start looking at making this thread safe. Probably need to add
comments with /* TODO - make thread safe */ so we know where to look.

Don't need to do it for this patch set, but we need to remember. The
comment might help for now (that is, add the comment to the next series).

-- Steve

>  
>  	path = trace_find_tracing_dir();
>  	if (!path)
>  		goto out_free;
>  
> -	trace_seq_printf(seq, "echo '%s' > %s/synthetic_events\n",
> -			 synthetic_event, path);
> +	trace_seq_printf(seq, "echo '%s%s %s' > %s/%s\n",
> +			 synth->dyn_event->prefix, synth->dyn_event->event,
> +			 synth->dyn_event->format, path, synth->dyn_event->trace_file);
>  
>  	tracefs_put_tracing_file(path);
>  	path = tracefs_instance_get_dir(instance);
> @@ -2116,10 +2099,18 @@ int tracefs_synth_show(struct trace_seq *seq,
>  			 hist, path, synth->end_event->system,
>  			 synth->end_event->name);
>  
> +	if (new_event) {
> +		tracefs_dynevent_free(synth->dyn_event);
> +		synth->dyn_event = NULL;
> +	}
> +
>  	ret = 0;
>   out_free:
> -	free(synthetic_event);
>  	free(hist);
>  	tracefs_put_tracing_file(path);
> +	if (new_event) {
> +		tracefs_dynevent_free(synth->dyn_event);
> +		synth->dyn_event = NULL;
> +	}
>  	return ret;
>  }

Re: [PATCH v4 04/10] libtracefs: Change tracefs_kprobe_info API

[Tzvetomir Stoyanov]

On Thu, Nov 4, 2021 at 6:33 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Thu,  4 Nov 2021 13:10:41 +0200
> "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:
>
> > +enum tracefs_dynevent_type tracefs_kprobe_info(struct tracefs_dynevent *kprobe,
> > +                                            char **system, char **event,
> > +                                            char **prefix, char **addr, char **format)
> > +{
> > +     char **lv[] = { system, event, prefix, addr, format };
> > +     char **rv[] = { &kprobe->system, &kprobe->event, &kprobe->prefix,
> > +                     &kprobe->address, &kprobe->format };
> > +     int i;
> > +
> > +     if (!kprobe)
> > +             return TRACEFS_DYNEVENT_MAX;
> > +
> > +     for (i = 0; i < ARRAY_SIZE(lv); i++)
> > +             *lv[i] = NULL;
>
> Do we really need to initialize them to NULL here?
>
> Not to mention, if one of the parameters is NULL itself, this will SEGFAULT.
>

I'll add a check for that. They should be set to NULL to ensure that
free() in the error path will not segfault, if the caller passes not
initialised pointers.

> > +
> > +     for (i = 0; i < ARRAY_SIZE(lv); i++) {
>
> Nice use of ARRAY_SIZE() ;-)
>
> > +             if (lv[i]) {
> > +                     if (*rv[i]) {
> > +                             *lv[i] = strdup(*rv[i]);
> > +                             if (!*lv[i])
> > +                                     goto error;
> > +                     } else {
> > +                             *lv[i] = NULL;
> >                       }
>
> The above here sets it to NULL if the parameter is non NULL.
>
> We don't need the initial NULL setting loop.
>
> -- Steve
>
>
> > -                     break;
> >               }
> > -             ret = parse_kprobe(NULL, &saveptr, &ktype, &system, &probe,
> > -                                &kaddr, &kfmt);
> >       }
> > -     free(content);
> > -     return rtype;
> > +
> > +     return kprobe->type;
> > +
> > +error:
> > +     for (i--; i >= 0; i--) {
> > +             if (lv[i])
> > +                     free(*lv[i]);
> > +     }
> > +
> > +     return TRACEFS_DYNEVENT_MAX;
> >  }
>


-- 
Tzvetomir (Ceco) Stoyanov
VMware Open Source Technology Center

Re: [PATCH v4 04/10] libtracefs: Change tracefs_kprobe_info API

[Steven Rostedt]

On Thu, 4 Nov 2021 19:28:49 +0200
Tzvetomir Stoyanov <tz.stoyanov@gmail.com> wrote:

> On Thu, Nov 4, 2021 at 6:33 PM Steven Rostedt <rostedt@goodmis.org> wrote:
> >
> > On Thu,  4 Nov 2021 13:10:41 +0200
> > "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:
> >  
> > > +enum tracefs_dynevent_type tracefs_kprobe_info(struct tracefs_dynevent *kprobe,
> > > +                                            char **system, char **event,
> > > +                                            char **prefix, char **addr, char **format)
> > > +{
> > > +     char **lv[] = { system, event, prefix, addr, format };
> > > +     char **rv[] = { &kprobe->system, &kprobe->event, &kprobe->prefix,
> > > +                     &kprobe->address, &kprobe->format };
> > > +     int i;
> > > +
> > > +     if (!kprobe)
> > > +             return TRACEFS_DYNEVENT_MAX;
> > > +
> > > +     for (i = 0; i < ARRAY_SIZE(lv); i++)
> > > +             *lv[i] = NULL;  
> >
> > Do we really need to initialize them to NULL here?
> >
> > Not to mention, if one of the parameters is NULL itself, this will SEGFAULT.
> >  
> 
> I'll add a check for that. They should be set to NULL to ensure that
> free() in the error path will not segfault, if the caller passes not
> initialised pointers.

It wont, due to the fact that it starts at i and works backward down to
zero. The only items it will look at are the ones that were already
initialized. Which is why I did it that way.

> 
> > > +
> > > +     for (i = 0; i < ARRAY_SIZE(lv); i++) {  
> >
> > Nice use of ARRAY_SIZE() ;-)
> >  
> > > +             if (lv[i]) {
> > > +                     if (*rv[i]) {
> > > +                             *lv[i] = strdup(*rv[i]);
> > > +                             if (!*lv[i])
> > > +                                     goto error;
> > > +                     } else {
> > > +                             *lv[i] = NULL;
> > >                       }  

> > > +
> > > +     return kprobe->type;
> > > +
> > > +error:
> > > +     for (i--; i >= 0; i--) {

The above means that we do not need to initialize anything that wasn't
touched.

-- Steve


> > > +             if (lv[i])
> > > +                     free(*lv[i]);
> > > +     }
> > > +
> > > +     return TRACEFS_DYNEVENT_MAX;
> > >  }  
> >  
> 
> 

Re: [PATCH v4 09/10] libtracefs: Update kprobes man pages

[Steven Rostedt]

On Thu,  4 Nov 2021 13:10:46 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> As there are a lot of changes in the libtracefs kprobes APIs, the
> documentation of the library should be updated.
> 
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> ---
>  Documentation/libtracefs-kprobes.txt | 111 +++++++++++++--------------
>  Documentation/libtracefs.txt         |   7 ++
>  2 files changed, 60 insertions(+), 58 deletions(-)
> 
> diff --git a/Documentation/libtracefs-kprobes.txt b/Documentation/libtracefs-kprobes.txt
> index c10576e..fedac96 100644
> --- a/Documentation/libtracefs-kprobes.txt
> +++ b/Documentation/libtracefs-kprobes.txt
> @@ -3,7 +3,9 @@ libtracefs(3)
>  
>  NAME
>  ----
> -tracefs_kprobe_raw, tracefs_kretprobe_raw, tracefs_get_kprobes, tracefs_kprobe_info, tracefs_kprobe_clear_all, tracefs_kprobe_clear_probe - Create, list, and destroy kprobes
> +tracefs_kprobe_alloc, tracefs_kretprobe_alloc, tracefs_kprobe_info,
> +tracefs_kprobe_raw, tracefs_kretprobe_raw - Allocate, get, and create kprobes
> +
>  
>  SYNOPSIS
>  --------
> @@ -11,18 +13,44 @@ SYNOPSIS
>  --
>  *#include <tracefs.h>*
>  
> -int tracefs_kprobe_raw(const char pass:[*]system, const char pass:[*]event, const char pass:[*]addr, const char pass:[*]format);
> -int tracefs_kretprobe_raw(const char pass:[*]system, const char pass:[*]event, const char pass:[*]addr, const char pass:[*]format);
> -char pass:[*]pass:[*]tracefs_get_kprobes(enum tracefs_kprobe_type type);
> -enum tracefs_kprobe_type tracefs_kprobe_info(const char pass:[*]group, const char pass:[*]event,
> -					     char pass:[*]pass:[*]type, char pass:[*]pass:[*]addr, char pass:[*]pass:[*]format);
> -enum tracefs_kprobe_type tracefs_kprobe_type(const char pass:[*]group, const char pass:[*]event)
> -int tracefs_kprobe_clear_all(bool force);
> -int tracefs_kprobe_clear_probe(const char pass:[*]system, const char pass:[*]event, bool force);
> +struct tracefs_dynevent pass:[*]
> +*tracefs_kprobe_alloc*(const char pass:[*]_system_, const char pass:[*]_event_,
> +		       const char pass:[*]_addr_, const char pass:[*]_format_);
> +struct tracefs_dynevent pass:[*]
> +*tracefs_kretprobe_alloc*(const char pass:[*]_system_, const char pass:[*]_event_,
> +			  const char pass:[*]_addr_, const char pass:[*]_format_, int _max_);
> +enum tracefs_dynevent_type *tracefs_kprobe_info*(struct tracefs_dynevent pass:[*]_kprobe_,
> +						char pass:[*]pass:[*]_system_, char pass:[*]pass:[*]_event_,
> +						char pass:[*]pass:[*]_prefix_, char pass:[*]pass:[*]_addr_,
> +						char pass:[*]pass:[*]_format_);
> +int *tracefs_kprobe_raw*(const char pass:[*]_system_, const char pass:[*]_event_,
> +			 const char pass:[*]_addr_, const char pass:[*]_format_);
> +int *tracefs_kretprobe_raw*(const char pass:[*]_system_, const char pass:[*]_event_,
> +			    const char pass:[*]_addr_, const char pass:[*]_format_);
>  --
>  
>  DESCRIPTION
>  -----------
> +*tracefs_kprobe_alloc*() allocates a new kprobe context. The kbrobe is not configured in the system.
> +The new kprobe will be in the _system_ group (or kprobes if _system_ is NULL). Have the name of

               "is NULL) and have the name of"

> +_event_ (or _addr_ if _event_ is NULL). Will be inserted to _addr_ (function name, with or without

Need proper grammar here:  "The kprobe will be inserted"

> +offset, or a address). And the _format_ will define the format of the kprobe. See the Linux

  "), and the _format_"

> +documentation file under: Documentation/trace/kprobetrace.rst
> +
> +*tracefs_kretprobe_alloc*() is the same as *tracefs_kprobe_alloc*, but allocates context for
> +kretprobe. It has one additional parameter, which is optional, _max_ - maxactive count.
> +See description of kretprobes in the Documentation/trace/kprobetrace.rst file.
> +
> +*tracefs_kprobe_info*() returns the type and information of a given _kprobe_. If any of the
> +_system_, _event_, _prefix_, _addr_ or _format_ arguments are not NULL, then strings are allocated
> +and returned back via these arguments. The _system_ and _event_ holds the system and the name of the
> +kprobe. If _prefix_ is non NULL, then it will hold an allocated string that holds the prefix portion
> +of the kprobe in the kprobe_events file (the content up to the ":", including it). Note that for
> +kretprobes, the max active count is encoded in the prefix srting. If _addr_ is non NULL, it will
> +hold the address or function that the kprobe is attached to. If _format_ is non NULL, it will hold
> +the format string of the kprobe. Note, that the content in _group_, _event_, _prefix_, _addr_, and
> +_format_ must be freed with free(3) if they are set.
> +
>  *tracefs_kprobe_raw*() will create a kprobe event. If _system_ is NULL, then
>  the default "kprobes" is used for the group (event system). Otherwise if _system_
>  is specified then the kprobe will be created under the group by that name. The
> @@ -36,55 +64,21 @@ document.
>  creates a kretprobe instead of a kprobe. The difference is also described
>  in the Linux kernel source in the Documentation/trace/kprobetrace.rst file.
>  
> -*tracefs_get_kprobes*() returns an array of strings (char pass:[*]) that contain
> -the registered kprobes and kretprobes depending on the given _type_. If _type_ is
> -TRACEFS_ALL_KPROBES, then all kprobes found are returned. If _type_ is
> -TRACEFS_KPROBE, then only normal kprobes are returned. If _type_ is
> -TRACEFS_KRETPROBE, then only kretprobes are returned.
> -The names are in the "system/event" format.
> -That is, one string holds both the kprobe's name as well as the group it is
> -defined under. These strings are allocated and may be modified with the
> -*strtok*(3) and *strtok_r*(3) functions. The string returned must be freed with
> -*tracefs_list_free*(3).
> -
> -*tracefs_kprobe_info*() returns the type of the given kprobe. If _group_ is
> -NULL, then the default "kprobes" is used. If _type_ is non NULL, then it will
> -hold an allocated string that holds the type portion of the kprobe in the
> -kprobe_events file (the content before the ":"). If _addr_ is non NULL, it will
> -hold the address or function that the kprobe is attached to. If _format_ is non
> -NULL, it will hold the format string of the kprobe. Note, that the content in
> -_type_, _addr_, and _format_ must be freed with free(3) if they are set. Even
> -in the case of an error, as they may hold information of what caused the error.
> -
> -*tracefs_kprobe_clear_all*() will try to remove all kprobes that have been
> -registered. If the @force flag is set, it will then disable those kprobe events
> -if they are enabled and then try to clear the kprobes.
> -
> -*tracefs_kprobe_clear_probe*() will try to clear specified kprobes. If _system_
> -is NULL, then it will only clear the default kprobes under the "kprobes" group.
> -If _event_ is NULL, it will clear all kprobes under the given _system_. If the
> -_force_ flag is set, then it will disable the given kprobe events before clearing
> -them.
> -
>  RETURN VALUE
>  ------------
>  
> -*tracefs_kprobe_raw*(), *tracefs_kretprobe_raw*(), *tracefs_kprobe_clear_all*(),
> -and *tracefs_kprobe_clear_probe*() return 0 on success, or -1 on error.
> -
> -If a parsing error occurs on *tracefs_kprobe_raw*() or *tracefs_kretprobe_raw*()
> -then *tracefs_error_last*(3) may be used to retrieve the error message explaining
> -the parsing issue.
> +*tracefs_kprobe_raw*() and *tracefs_kretprobe_raw*() return 0 on success, or -1 on error.
> +If a parsing error occurs on *tracefs_kprobe_raw*() or *tracefs_kretprobe_raw*() then
> +*tracefs_error_last*(3) may be used to retrieve the error message explaining the parsing issue.
>  
> -*tracefs_get_kprobes*() returns an allocate string list of allocated strings
> -on success that must be freed with *tracefs_list_free*(3) and returns
> -NULL on error.
> +The *tracefs_kprobe_alloc*() and *tracefs_kretprobe_alloc*() APIs return pointer to allocated

  "APIs return a pointer to an allocated"

> +tracefs_dynevent structure, describing the probe. This pointer must be freed by
> +*tracefs_dynevent_free*(3).

 Add: "Note, this only allocates a descriptor representing the kprobe. It
      does not modify the running system."

>  
> -*tracefs_kprobe_info*() returns the type of the given kprobe. It returns
> -TRACEFS_KPROBE for normal kprobes, TRACEFS_KRETPROBE for kretprobes, and
> -on error, or if the kprobe is not found TRACEFS_ALL_KPROBES is returned.
> -If _type_, _addr_, or _format_ are non NULL, they will contain allocated
> -strings that must be freed by free(3) even in the case of error.
> +*tracefs_kprobe_info*() returns the type of the given kprobe. It returns TRACEFS_DYNEVENT_KPROBE for
> +normal kprobes, TRACEFS_DYNEVENT_KRETPROBE for kretprobes or TRACEFS_DYNEVENT_MAX on error.

I should have commented on this on the patch that implements this, but I
noticed it now. As TRACEFS_DYNEVENT_MAX may change in the future, we should
not use it for any API. And now that the enum represents bits, it an error
should return 0.

We can make: TRACFS_DYNEVENT_ERROR be zero in enum tracefs_dynevent_type.


> +If _system_, _event_, _prefix_, _addr_, or _format_ are non NULL, they will contain allocated
> +strings that must be freed by free(3).
>  
>  ERRORS
>  ------
> @@ -96,9 +90,10 @@ The following errors are for all the above calls:
>  
>  *ENOMEM* Memory allocation error.
>  
> -*tracefs_kprobe_raw*(), *tracefs_kretprobe_raw*() can fail with the following errors:
> +*tracefs_kprobe_raw*(), *tracefs_kretprobe_raw*(), *tracefs_kprobe_alloc*(),
> +and *tracefs_kretprobe_alloc*() can fail with the following errors:
>  
> -*EBADMSG* Either _addr_ or _format_ are NULL.
> +*EBADMSG* if _addr_ is NULL.
>  
>  *EINVAL*  Most likely a parsing error occurred (use *tracefs_error_last*(3) to possibly
>            see what that error was).
> @@ -217,7 +212,7 @@ int main (int argc, char **argv, char **env)
>  		exit(-1);
>  	}
>  
> -	tracefs_kprobe_clear_probe(mykprobe, NULL, true);
> +	tracefs_kprobe_destroy(NULL, true);

There is no tracefs_kprobe_destroy().

>  
>  	kprobe_create("open", "do_sys_openat2",
>  		      "file=+0($arg2):ustring flags=+0($arg3):x64 mode=+8($arg3):x64\n");
> @@ -247,7 +242,7 @@ int main (int argc, char **argv, char **env)
>  	} while (waitpid(pid, NULL, WNOHANG) != pid);
>  
>  	/* Will disable the events */
> -	tracefs_kprobe_clear_probe(mykprobe, NULL, true);
> +	tracefs_kprobe_destroy(NULL, true);

Here too.

-- Steve

>  	tracefs_instance_destroy(instance);
>  	tep_free(tep);
>  
> @@ -293,5 +288,5 @@ https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
>  
>  COPYING
>  -------
> -Copyright \(C) 2020 VMware, Inc. Free use of this software is granted under
> +Copyright \(C) 2021 VMware, Inc. Free use of this software is granted under
>  the terms of the GNU Public License (GPL).
> diff --git a/Documentation/libtracefs.txt b/Documentation/libtracefs.txt
> index 2c9eabd..f679002 100644
> --- a/Documentation/libtracefs.txt
> +++ b/Documentation/libtracefs.txt
> @@ -63,6 +63,13 @@ Writing data in the trace buffer:
>  
>  Control library logs:
>  	int *tracefs_set_loglevel*(enum tep_loglevel _level_);
> +
> +Kprobes and Kretprobes:
> +	struct tracefs_dynevent pass:[*] *tracefs_kprobe_alloc*(const char pass:[*]_system_, const char pass:[*]_event_, const char pass:[*]_addr_, const char pass:[*]_format_);
> +	struct tracefs_dynevent pass:[*] *tracefs_kretprobe_alloc*(const char pass:[*]_system_, const char pass:[*]_event_, const char pass:[*]_addr_, const char pass:[*]_format_, int _max_);
> +	enum tracefs_kprobe_type *tracefs_kprobe_info*(struct tracefs_dynevent pass:[*]_kprobe_, char pass:[*]pass:[*]_system_, char pass:[*]pass:[*]_event_, char pass:[*]pass:[*]_prefix_, char pass:[*]pass:[*]_addr_, char pass:[*]pass:[*]_format_);
> +	int *tracefs_kprobe_raw*(const char pass:[*]_system_, const char pass:[*]_event_, const char pass:[*]_addr_, const char pass:[*]_format_);
> +	int *tracefs_kretprobe_raw*(const char pass:[*]_system_, const char pass:[*]_event_, const char pass:[*]_addr_, const char pass:[*]_format_);
>  --
>  
>  DESCRIPTION

Re: [PATCH v4 08/10] libtracefs: Use the internal dynamic events API when creating synthetic events

[Tzvetomir Stoyanov]

On Thu, Nov 4, 2021 at 7:13 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
[ ... ]
> >  static int remove_hist(struct tracefs_instance *instance,
> >                      struct tep_event *event, const char *hist)
> >  {
> > @@ -1919,7 +1911,6 @@ tracefs_synth_get_start_hist(struct tracefs_synth *synth)
> >  int tracefs_synth_create(struct tracefs_instance *instance,
> >                        struct tracefs_synth *synth)
>
> I think we should call this:
>
>         tracefs_synth_create_raw()
>
> that passes in the "instance".
>
> Then we could have tracefs_synth_create() just use the top instance (no
> instance passed to it), and we could decide later if we want to create an
> internal instance or not to do the work to keep from modifying the top
> instance.
>
> That is, we would have:
>
> int tracefs_synth_create(struct tracefs_synth *synth)
> {
>         return tracefs_synth_create_raw(synth->create_instance, synth);
> }
>
> Have synth->create_instance be defaulted to NULL on allocation, and would
> get updated by another interface perhaps?
>
> We could also add to the _raw() function:
>
>         if (synth->create_instance && instance &&
>             synth->create_instance != instance) {
>                 errno = EINVAL;
>                 return -1
>         }
>
>         if (!synth->create_instance && instance) {
>                 syth->create_instance = instance;
>                 trace_get_instance(instance);
>         }
>
> Would need to have in the destructor:
>
>         if (synth->create_instance)
>                 trace_put_instance(synth->create_instance);
>
>
> Or something like that.
>

I looked and tested more this code today, but as I understood the
instance is mandatory in histograms creation and should not be removed
from this API. That API appends the histogram config in the event's
trigger files, which is for specific instances. The histogram is
accumulated only in the context of that instance. I'm going to send
next version of the patch set, but without changes to this API.

>
[ ... ]
>


-- 
Tzvetomir (Ceco) Stoyanov
VMware Open Source Technology Center

Re: [PATCH v4 08/10] libtracefs: Use the internal dynamic events API when creating synthetic events

[Steven Rostedt]

On Fri, 5 Nov 2021 14:15:05 +0200
Tzvetomir Stoyanov <tz.stoyanov@gmail.com> wrote:

> I looked and tested more this code today, but as I understood the
> instance is mandatory in histograms creation and should not be removed
> from this API. That API appends the histogram config in the event's
> trigger files, which is for specific instances. The histogram is
> accumulated only in the context of that instance. I'm going to send
> next version of the patch set, but without changes to this API.

The histogram code is internal to the synthetic events. That's because it
uses the histogram to save the data across the start to end event to create
the synthetic event. The histogram is an implementation detail of the
synthetic event and should not be exposed via the API. And that is
*exactly* why instances should not be exposed to the synthetic event!

In fact, I don't wan the user to have control over the instances because
they are likely to screw it up if they don't know what they are doing.
That's why I suggested to convert the current API into a raw event, because
to use instances, you had better know what you are doing, otherwise you can
easily screw it up.

The histograms used by synthetic events are "special" and if not done
properly, will not do what people expect.

If you don't want to make this change, I will.

-- Steve