tracing/events: convert event call sites to use a link list
Impact: makes it possible to define events in modules
The events are created by reading down the section that they are linked
in by the macros. But this is not scalable to modules. This patch converts
the manipulations to use a global link list, and on boot up it adds
the items in the section to the list.
This change will allow modules to add their tracing events to the list as
well.
Note, this change alone does not permit modules to use the TRACE_EVENT macros,
but the change is needed for them to eventually do so.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index ead68ac..5c66aaf 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -19,6 +19,8 @@
static DEFINE_MUTEX(event_mutex);
+LIST_HEAD(ftrace_events);
+
int trace_define_field(struct ftrace_event_call *call, char *type,
char *name, int offset, int size)
{
@@ -54,16 +56,14 @@
static void ftrace_clear_events(void)
{
- struct ftrace_event_call *call = (void *)__start_ftrace_events;
+ struct ftrace_event_call *call;
-
- while ((unsigned long)call < (unsigned long)__stop_ftrace_events) {
+ list_for_each_entry(call, &ftrace_events, list) {
if (call->enabled) {
call->enabled = 0;
call->unregfunc();
}
- call++;
}
}
@@ -89,7 +89,7 @@
static int ftrace_set_clr_event(char *buf, int set)
{
- struct ftrace_event_call *call = __start_ftrace_events;
+ struct ftrace_event_call *call;
char *event = NULL, *sub = NULL, *match;
int ret = -EINVAL;
@@ -118,7 +118,7 @@
}
mutex_lock(&event_mutex);
- for_each_event(call) {
+ list_for_each_entry(call, &ftrace_events, list) {
if (!call->name || !call->regfunc)
continue;
@@ -224,15 +224,17 @@
static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
- struct ftrace_event_call *call = m->private;
- struct ftrace_event_call *next = call;
+ struct list_head *list = m->private;
+ struct ftrace_event_call *call;
(*pos)++;
for (;;) {
- if ((unsigned long)call >= (unsigned long)__stop_ftrace_events)
+ if (list == &ftrace_events)
return NULL;
+ call = list_entry(list, struct ftrace_event_call, list);
+
/*
* The ftrace subsystem is for showing formats only.
* They can not be enabled or disabled via the event files.
@@ -240,11 +242,10 @@
if (call->regfunc)
break;
- call++;
- next = call;
+ list = list->next;
}
- m->private = ++next;
+ m->private = list->next;
return call;
}
@@ -257,22 +258,23 @@
static void *
s_next(struct seq_file *m, void *v, loff_t *pos)
{
- struct ftrace_event_call *call = m->private;
- struct ftrace_event_call *next;
+ struct list_head *list = m->private;
+ struct ftrace_event_call *call;
(*pos)++;
retry:
- if ((unsigned long)call >= (unsigned long)__stop_ftrace_events)
+ if (list == &ftrace_events)
return NULL;
+ call = list_entry(list, struct ftrace_event_call, list);
+
if (!call->enabled) {
- call++;
+ list = list->next;
goto retry;
}
- next = call;
- m->private = ++next;
+ m->private = list->next;
return call;
}
@@ -312,7 +314,7 @@
if (!ret) {
struct seq_file *m = file->private_data;
- m->private = __start_ftrace_events;
+ m->private = ftrace_events.next;
}
return ret;
}
@@ -797,9 +799,17 @@
return 0;
}
+extern struct ftrace_event_call __start_ftrace_events[];
+extern struct ftrace_event_call __stop_ftrace_events[];
+
+#define for_each_event(event) \
+ for (event = __start_ftrace_events; \
+ (unsigned long)event < (unsigned long)__stop_ftrace_events; \
+ event++)
+
static __init int event_trace_init(void)
{
- struct ftrace_event_call *call = __start_ftrace_events;
+ struct ftrace_event_call *call;
struct dentry *d_tracer;
struct dentry *entry;
struct dentry *d_events;
@@ -830,6 +840,7 @@
/* The linker may leave blanks */
if (!call->name)
continue;
+ list_add(&call->list, &ftrace_events);
event_create_dir(call, d_events);
}