tracing: add run-time field descriptions for event filtering
This patch makes the field descriptions defined for event tracing
available at run-time, for the event-filtering mechanism introduced
in a subsequent patch.
The common event fields are prepended with 'common_' in the format
display, allowing them to be distinguished from the other fields
that might internally have same name and can therefore be
unambiguously used in filters.
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237710639.7703.46.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 3047b56..961b057 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -19,6 +19,34 @@
static DEFINE_MUTEX(event_mutex);
+int trace_define_field(struct ftrace_event_call *call, char *type,
+ char *name, int offset, int size)
+{
+ struct ftrace_event_field *field;
+
+ field = kmalloc(sizeof(*field), GFP_KERNEL);
+ if (!field)
+ goto err;
+ field->name = kstrdup(name, GFP_KERNEL);
+ if (!field->name)
+ goto err;
+ field->type = kstrdup(type, GFP_KERNEL);
+ if (!field->type)
+ goto err;
+ field->offset = offset;
+ field->size = size;
+ list_add(&field->link, &call->fields);
+
+ return 0;
+err:
+ if (field) {
+ kfree(field->name);
+ kfree(field->type);
+ }
+ kfree(field);
+ return -ENOMEM;
+}
+
static void ftrace_clear_events(void)
{
struct ftrace_event_call *call = (void *)__start_ftrace_events;
@@ -343,7 +371,8 @@
#undef FIELD
#define FIELD(type, name) \
- #type, #name, offsetof(typeof(field), name), sizeof(field.name)
+ #type, "common_" #name, offsetof(typeof(field), name), \
+ sizeof(field.name)
static int trace_write_header(struct trace_seq *s)
{
@@ -581,6 +610,15 @@
call->name);
}
+ if (call->define_fields) {
+ ret = call->define_fields();
+ if (ret < 0) {
+ pr_warning("Could not initialize trace point"
+ " events/%s\n", call->name);
+ return ret;
+ }
+ }
+
/* A trace may not want to export its format */
if (!call->show_format)
return 0;
