[RFC][PATCH 1/3] tracing: Add trace_array parameter to create_event_filter()

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>

Pass in the trace_array that represents the instance the filter being
changed is in to create_event_filter(). This will allow for error messages
that happen when writing to the filter can be displayed in the proper
instance "error_log" file.

Note, for calls to create_filter() (that was also modified to support
create_event_filter()), that changes filters that do not exist in a instance
(for perf for example), NULL may be passed in, which means that there will
not be any message to log for that filter.

Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
 kernel/trace/trace.h                |  3 ++-
 kernel/trace/trace_events_filter.c  | 21 ++++++++++++---------
 kernel/trace/trace_events_trigger.c |  3 ++-
 3 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index b711edbef7e7..809c5d7f0064 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1553,7 +1553,8 @@ extern int apply_subsystem_event_filter(struct trace_subsystem_dir *dir,
 extern void print_subsystem_event_filter(struct event_subsystem *system,
 					 struct trace_seq *s);
 extern int filter_assign_type(const char *type);
-extern int create_event_filter(struct trace_event_call *call,
+extern int create_event_filter(struct trace_array *tr,
+			       struct trace_event_call *call,
 			       char *filter_str, bool set_str,
 			       struct event_filter **filterp);
 extern void free_event_filter(struct event_filter *filter);
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 290d42c59101..b1033638e499 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -920,7 +920,8 @@ static void remove_filter_string(struct event_filter *filter)
 	filter->filter_string = NULL;
 }
 
-static void append_filter_err(struct filter_parse_error *pe,
+static void append_filter_err(struct trace_array *tr,
+			      struct filter_parse_error *pe,
 			      struct event_filter *filter)
 {
 	struct trace_seq *s;
@@ -1607,7 +1608,7 @@ static int process_system_preds(struct trace_subsystem_dir *dir,
 		if (err) {
 			filter_disable(file);
 			parse_error(pe, FILT_ERR_BAD_SUBSYS_FILTER, 0);
-			append_filter_err(pe, filter);
+			append_filter_err(tr, pe, filter);
 		} else
 			event_set_filtered_flag(file);
 
@@ -1719,7 +1720,8 @@ static void create_filter_finish(struct filter_parse_error *pe)
  * information if @set_str is %true and the caller is responsible for
  * freeing it.
  */
-static int create_filter(struct trace_event_call *call,
+static int create_filter(struct trace_array *tr,
+			 struct trace_event_call *call,
 			 char *filter_string, bool set_str,
 			 struct event_filter **filterp)
 {
@@ -1736,17 +1738,18 @@ static int create_filter(struct trace_event_call *call,
 
 	err = process_preds(call, filter_string, *filterp, pe);
 	if (err && set_str)
-		append_filter_err(pe, *filterp);
+		append_filter_err(tr, pe, *filterp);
 	create_filter_finish(pe);
 
 	return err;
 }
 
-int create_event_filter(struct trace_event_call *call,
+int create_event_filter(struct trace_array *tr,
+			struct trace_event_call *call,
 			char *filter_str, bool set_str,
 			struct event_filter **filterp)
 {
-	return create_filter(call, filter_str, set_str, filterp);
+	return create_filter(tr, call, filter_str, set_str, filterp);
 }
 
 /**
@@ -1773,7 +1776,7 @@ static int create_system_filter(struct trace_subsystem_dir *dir,
 			kfree((*filterp)->filter_string);
 			(*filterp)->filter_string = NULL;
 		} else {
-			append_filter_err(pe, *filterp);
+			append_filter_err(tr, pe, *filterp);
 		}
 	}
 	create_filter_finish(pe);
@@ -1804,7 +1807,7 @@ int apply_event_filter(struct trace_event_file *file, char *filter_string)
 		return 0;
 	}
 
-	err = create_filter(call, filter_string, true, &filter);
+	err = create_filter(file->tr, call, filter_string, true, &filter);
 
 	/*
 	 * Always swap the call filter with the new filter
@@ -2060,7 +2063,7 @@ int ftrace_profile_set_filter(struct perf_event *event, int event_id,
 	if (event->filter)
 		goto out_unlock;
 
-	err = create_filter(call, filter_str, false, &filter);
+	err = create_filter(NULL, call, filter_str, false, &filter);
 	if (err)
 		goto free_filter;
 
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index cd12ecb66eb9..2a2912cb4533 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -731,7 +731,8 @@ int set_trigger_filter(char *filter_str,
 		goto out;
 
 	/* The filter is for the 'trigger' event, not the triggered event */
-	ret = create_event_filter(file->event_call, filter_str, false, &filter);
+	ret = create_event_filter(file->tr, file->event_call,
+				  filter_str, false, &filter);
 	/*
 	 * If create_event_filter() fails, filter still needs to be freed.
 	 * Which the calling code will do with data->filter.
-- 
2.20.1