[PATCH v2] libtracefs: New API for clearing filter on event

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

There is no API for clearing filter from event. After adding an API that
applys a filter we must provide an identical API for clearing the filter.

Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
---
 Documentation/libtracefs-filter.txt |  8 +++++++-
 include/tracefs.h                   |  3 ++-
 src/tracefs-filter.c                | 14 ++++++++++++++
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/Documentation/libtracefs-filter.txt b/Documentation/libtracefs-filter.txt
index 7db3d60..f7bbb17 100644
--- a/Documentation/libtracefs-filter.txt
+++ b/Documentation/libtracefs-filter.txt
@@ -3,7 +3,7 @@ libtracefs(3)
 
 NAME
 ----
-tracefs_filter_string_append, tracefs_filter_string_verify, tracefs_event_apply_filter -
+tracefs_filter_string_append, tracefs_filter_string_verify, tracefs_event_filter_apply tracefs_event_filter_clear -
 Add, verify and apply event filters
 
 SYNOPSIS
@@ -17,6 +17,8 @@ int tracefs_filter_string_append(struct tep_event pass:[*]event, char pass:[**]
 				 enum tracefs_synth_compare compare, const char pass:[*]val);
 int tracefs_filter_string_verify(struct tep_event pass:[*]event, const char pass:[*]filter, char pass:[**]err);
 int tracefs_event_filter_apply(struct tracefs_instance pass:[*]instance, struct tep_event pass:[*]event, const char pass:[*]filter);
+int tracefs_event_filter_clear(struct tracefs_instance pass:[*]instance, struct tep_event pass:[*]event);
+
 --
 
 DESCRIPTION
@@ -69,6 +71,8 @@ with *free*().
 
 *tracefs_event_filter_apply*() applies given _filter_ string on _event_ in given _instance_.
 
+*tracefs_event_filter_clear*() clear all filters on _event_ in given _instance_.
+
 RETURN VALUE
 ------------
 *tracefs_filter_string_append*() returns 0 on success and -1 on error.
@@ -80,6 +84,8 @@ freed with *free*().
 
 *tracefs_event_filter_apply*() returns 0 on success and -1 on error.
 
+*tracefs_event_filter_clear*() returns 0 on success and -1 on error.
+
 EXAMPLE
 -------
 [source,c]
diff --git a/include/tracefs.h b/include/tracefs.h
index ac92dca..3ac3d9c 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -479,6 +479,8 @@ int tracefs_filter_string_verify(struct tep_event *event, const char *filter,
 int tracefs_event_filter_apply(struct tracefs_instance *instance,
 			       struct tep_event *event, const char *filter);
 
+int tracefs_event_filter_clear(struct tracefs_instance *instance,
+			       struct tep_event *event);
 
 /** Deprecated do not use: Instead use tracefs_filter_string_append() **/
 int tracefs_event_append_filter(struct tep_event *event, char **filter,
@@ -490,7 +492,6 @@ int tracefs_event_append_filter(struct tep_event *event, char **filter,
 int tracefs_event_verify_filter(struct tep_event *event, const char *filter,
 				char **err);
 
-
 #define TRACEFS_TIMESTAMP "common_timestamp"
 #define TRACEFS_TIMESTAMP_USECS "common_timestamp.usecs"
 
diff --git a/src/tracefs-filter.c b/src/tracefs-filter.c
index 7bc36fe..85d0be1 100644
--- a/src/tracefs-filter.c
+++ b/src/tracefs-filter.c
@@ -764,6 +764,20 @@ int tracefs_event_filter_apply(struct tracefs_instance *instance,
 					"filter", filter);
 }
 
+/**
+ * tracefs_event_filter_clear - clear the filter on event in given instance
+ * @instance: The instance in which the filter will be applied (NULL for toplevel).
+ * @event: The event to apply the filter on.
+ *
+ * Returns 0 on succes and -1 on error.
+ */
+int tracefs_event_filter_clear(struct tracefs_instance *instance,
+			       struct tep_event *event)
+{
+	return tracefs_event_file_write(instance, event->system, event->name,
+					"filter", "0");
+}
+
 /** Deprecated **/
 int tracefs_event_append_filter(struct tep_event *event, char **filter,
 				enum tracefs_filter type,
-- 
2.32.0