tracing: Separate out trace events from global variables

The trace events for ftrace are all defined via global variables.
The arrays of events and event systems are linked to a global list.
This prevents multiple users of the event system (what to enable and
what not to).

By adding descriptors to represent the event/file relation, as well
as to which trace_array descriptor they are associated with, allows
for more than one set of events to be defined. Once the trace events
files have a link between the trace event and the trace_array they
are associated with, we can create multiple trace_arrays that can
record separate events in separate buffers.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4f1dade56981..932931897b8d 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -189,6 +189,8 @@ unsigned long long ns2usecs(cycle_t nsec)
  */
 static struct trace_array       global_trace;
 
+LIST_HEAD(ftrace_trace_arrays);
+
 static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
 
 int filter_current_check_discard(struct ring_buffer *buffer,
@@ -5359,6 +5361,12 @@ __init static int tracer_alloc_buffers(void)
 
         register_die_notifier(&trace_die_notifier);
 
+        global_trace.flags = TRACE_ARRAY_FL_GLOBAL;
+
+        INIT_LIST_HEAD(&global_trace.systems);
+        INIT_LIST_HEAD(&global_trace.events);
+        list_add(&global_trace.list, &ftrace_trace_arrays);
+
         while (trace_boot_options) {
                 char *option;