[PATCH v2 4/5] libtracefs: Option's bit masks to be owned by the instance

["Yordan Karadzhov (VMware)" <y.karadz@gmail.com>]

If the instance owns two mask objects, we no longer need to
dynamically allocate memory in tracefs_options_get_supported() and
tracefs_options_get_enabled(). This will simplify the code on the
caller side, since the user is no longer responsible for freeing
those masks.

Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
---
 Documentation/libtracefs-option-get.txt |  4 +---
 include/tracefs-local.h                 |  6 ++++++
 include/tracefs.h                       |  2 +-
 src/tracefs-instance.c                  | 14 ++++++++++++++
 src/tracefs-tools.c                     | 18 ++++++++----------
 5 files changed, 30 insertions(+), 14 deletions(-)

diff --git a/Documentation/libtracefs-option-get.txt b/Documentation/libtracefs-option-get.txt
index 9b3cb56..3290f24 100644
--- a/Documentation/libtracefs-option-get.txt
+++ b/Documentation/libtracefs-option-get.txt
@@ -52,14 +52,13 @@ EXAMPLE
 --
 #include <tracefs.h>
 ...
-struct tracefs_options_mask *options;
+const struct tracefs_options_mask *options;
 ...
 options = tracefs_options_get_supported(NULL);
 if (!options) {
 	/* Failed to get supported options */
 } else {
 	...
-	free(options);
 }
 ...
 options = tracefs_options_get_enabled(NULL);
@@ -67,7 +66,6 @@ if (!options) {
 	/* Failed to get options, enabled in the top instance */
 } else {
 	...
-	free(options);
 }
 ...
 
diff --git a/include/tracefs-local.h b/include/tracefs-local.h
index 0a746f2..0a083f9 100644
--- a/include/tracefs-local.h
+++ b/include/tracefs-local.h
@@ -37,4 +37,10 @@ struct tracefs_options_mask {
 	unsigned long long	mask;
 };
 
+struct tracefs_options_mask *
+supported_opts_mask(struct tracefs_instance *instance);
+
+struct tracefs_options_mask *
+enabled_opts_mask(struct tracefs_instance *instance);
+
 #endif /* _TRACE_FS_LOCAL_H */
diff --git a/include/tracefs.h b/include/tracefs.h
index 0665e8d..6e9cf55 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -132,7 +132,7 @@ enum tracefs_option_id {
 #define TRACEFS_OPTION_MAX (TRACEFS_OPTION_VERBOSE + 1)
 
 struct tracefs_options_mask;
-bool tracefs_option_is_set(struct tracefs_options_mask *options,
+bool tracefs_option_is_set(const struct tracefs_options_mask *options,
 			   enum tracefs_option_id id);
 struct tracefs_options_mask *tracefs_options_get_supported(struct tracefs_instance *instance);
 bool tracefs_option_is_supported(struct tracefs_instance *instance, enum tracefs_option_id id);
diff --git a/src/tracefs-instance.c b/src/tracefs-instance.c
index 0df313c..4d78be6 100644
--- a/src/tracefs-instance.c
+++ b/src/tracefs-instance.c
@@ -23,8 +23,22 @@ struct tracefs_instance {
 	char	*trace_dir;
 	char	*name;
 	int	flags;
+	struct tracefs_options_mask	supported_opts;
+	struct tracefs_options_mask	enabled_opts;
 };
 
+__hidden inline struct tracefs_options_mask *
+supported_opts_mask(struct tracefs_instance *instance)
+{
+	return &instance->supported_opts;
+}
+
+__hidden inline struct tracefs_options_mask *
+enabled_opts_mask(struct tracefs_instance *instance)
+{
+	return &instance->enabled_opts;
+}
+
 /**
  * instance_alloc - allocate a new ftrace instance
  * @trace_dir - Full path to the tracing directory, where the instance is
diff --git a/src/tracefs-tools.c b/src/tracefs-tools.c
index a932216..980ad47 100644
--- a/src/tracefs-tools.c
+++ b/src/tracefs-tools.c
@@ -215,9 +215,8 @@ static struct tracefs_options_mask *trace_get_options(struct tracefs_instance *i
 	DIR *dir = NULL;
 	long long val;
 
-	bitmask = calloc(1, sizeof(struct tracefs_options_mask));
-	if (!bitmask)
-		return NULL;
+	bitmask = enabled? enabled_opts_mask(instance) :
+			   supported_opts_mask(instance);
 	dname = tracefs_instance_get_file(instance, "options");
 	if (!dname)
 		goto error;
@@ -247,7 +246,6 @@ error:
 	if (dir)
 		closedir(dir);
 	tracefs_put_tracing_file(dname);
-	free(bitmask);
 	return NULL;
 }
 
@@ -255,8 +253,8 @@ error:
  * tracefs_options_get_supported - Get all supported trace options in given instance
  * @instance: ftrace instance, can be NULL for the top instance
  *
- * Returns allocated bitmask structure with all trace options, supported in given
- * instance, or NULL in case of an error. The returned structure must be freed with free()
+ * Returns bitmask structure with all trace options, supported in given instance,
+ * or NULL in case of an error.
  */
 struct tracefs_options_mask *tracefs_options_get_supported(struct tracefs_instance *instance)
 {
@@ -267,8 +265,8 @@ struct tracefs_options_mask *tracefs_options_get_supported(struct tracefs_instan
  * tracefs_options_get_enabled - Get all currently enabled trace options in given instance
  * @instance: ftrace instance, can be NULL for the top instance
  *
- * Returns allocated bitmask structure with all trace options, enabled in given
- * instance, or NULL in case of an error. The returned structure must be freed with free()
+ * Returns bitmask structure with all trace options, enabled in given instance,
+ * or NULL in case of an error.
  */
 struct tracefs_options_mask *tracefs_options_get_enabled(struct tracefs_instance *instance)
 {
@@ -278,7 +276,7 @@ struct tracefs_options_mask *tracefs_options_get_enabled(struct tracefs_instance
 static int trace_config_option(struct tracefs_instance *instance,
 			       enum tracefs_option_id id, bool set)
 {
-	char *set_str = set ? "1" : "0";
+	const char *set_str = set ? "1" : "0";
 	char file[PATH_MAX];
 	const char *name;
 
@@ -366,7 +364,7 @@ bool tracefs_option_is_enabled(struct tracefs_instance *instance, enum tracefs_o
  * Returns true if an option with given id is set in the bitmask,
  * false if it is not set.
  */
-bool tracefs_option_is_set(struct tracefs_options_mask *options,
+bool tracefs_option_is_set(const struct tracefs_options_mask *options,
 			   enum tracefs_option_id id)
 {
 	if (id > TRACEFS_OPTION_INVALID)
-- 
2.27.0