[for-next][PATCH 22/26] tracing: Define event fields early stage

Steven Rostedt
2020-09-22T01:25:03Z

Define event fields at early stage so that boot-time tracing can
access the event fields (like per-event filter setting).

Link: https://lkml.kernel.org/r/159974152862.478751.2023768466808361350.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace_events.c | 92 ++++++++++++++++++++++---------------
1 file changed, 55 insertions(+), 37 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index ee25d849ebba..8e87fbab6930 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -2123,12 +2123,48 @@ event_subsystem_dir(struct trace_array *tr, const char *name,
return NULL;
}

+static int
+event_define_fields(struct trace_event_call *call)
+{
+ struct list_head *head;
+ int ret = 0;
+
+ /*
+ * Other events may have the same class. Only update
+ * the fields if they are not already defined.
+ */
+ head = trace_get_fields(call);
+ if (list_empty(head)) {
+ struct trace_event_fields *field = call->class->fields_array;
+ unsigned int offset = sizeof(struct trace_entry);
+
+ for (; field->type; field++) {
+ if (field->type == TRACE_FUNCTION_TYPE) {
+ field->define_fields(call);
+ break;
+ }
+
+ offset = ALIGN(offset, field->align);
+ ret = trace_define_field(call, field->type, field->name,
+ offset, field->size,
+ field->is_signed, field->filter_type);
+ if (WARN_ON_ONCE(ret)) {
+ pr_err("error code is %d\n", ret);
+ break;
+ }
+
+ offset += field->size;
+ }
+ }
+
+ return ret;
+}
+
static int
event_create_dir(struct dentry *parent, struct trace_event_file *file)
{
struct trace_event_call *call = file->event_call;
struct trace_array *tr = file->tr;
- struct list_head *head;
struct dentry *d_events;
const char *name;
int ret;
@@ -2162,35 +2198,10 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file)
&ftrace_event_id_fops);
#endif

- /*
- * Other events may have the same class. Only update
- * the fields if they are not already defined.
- */
- head = trace_get_fields(call);
- if (list_empty(head)) {
- struct trace_event_fields *field = call->class->fields_array;
- unsigned int offset = sizeof(struct trace_entry);
-
- for (; field->type; field++) {
- if (field->type == TRACE_FUNCTION_TYPE) {
- ret = field->define_fields(call);
- break;
- }
-
- offset = ALIGN(offset, field->align);
- ret = trace_define_field(call, field->type, field->name,
- offset, field->size,
- field->is_signed, field->filter_type);
- if (ret)
- break;
-
- offset += field->size;
- }
- if (ret < 0) {
- pr_warn("Could not initialize trace point events/%s\n",
- name);
- return -1;
- }
+ ret = event_define_fields(call);
+ if (ret < 0) {
+ pr_warn("Could not initialize trace point events/%s\n", name);
+ return ret;
}

/*
@@ -2493,7 +2504,7 @@ __trace_early_add_new_event(struct trace_event_call *call,
if (!file)
return -ENOMEM;

- return 0;
+ return event_define_fields(call);
}

struct ftrace_module_file_ops;
@@ -3431,6 +3442,18 @@ static __init int event_trace_enable_again(void)

early_initcall(event_trace_enable_again);

+/* Init fields which doesn't related to the tracefs */
+static __init int event_trace_init_fields(void)
+{
+ if (trace_define_generic_fields())
+ pr_warn("tracing: Failed to allocated generic fields");
+
+ if (trace_define_common_fields())
+ pr_warn("tracing: Failed to allocate common fields");
+
+ return 0;
+}
+
__init int event_trace_init(void)
{
struct trace_array *tr;
@@ -3446,12 +3469,6 @@ __init int event_trace_init(void)
if (!entry)
pr_warn("Could not create tracefs 'available_events' entry\n");

- if (trace_define_generic_fields())
- pr_warn("tracing: Failed to allocated generic fields");
-
- if (trace_define_common_fields())
- pr_warn("tracing: Failed to allocate common fields");
-
ret = early_event_add_tracer(NULL, tr);
if (ret)
return ret;
@@ -3469,6 +3486,7 @@ void __init trace_event_init(void)
event_trace_memsetup();
init_ftrace_syscalls();
event_trace_enable();
+ event_trace_init_fields();
}

#ifdef CONFIG_EVENT_TRACE_STARTUP_TEST
--
2.28.0