tracing/function_graph: Fix filters for function_graph threshold

Function graph tracer currently ignores filters if tracing_thresh is set.
For example, even if set_ftrace_pid is set, then its ignored if tracing_thresh
set, resulting in all processes being traced.

To fix this, we reuse the same entry function as when tracing_thresh is not
set and do everything as in the regular case except for writing the function entry
to the ring buffer.

Link: http://lkml.kernel.org/r/1466228694-2677-1-git-send-email-agnel.joel@gmail.com

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Joel Fernandes <agnel.joel@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 8 insertions, 9 deletions

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 67cce7896aeb..7363ccf79512 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -338,6 +338,13 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
         if (ftrace_graph_notrace_addr(trace->func))
                 return 1;
 
+        /*
+         * Stop here if tracing_threshold is set. We only write function return
+         * events to the ring buffer.
+         */
+        if (tracing_thresh)
+                return 1;
+
         local_irq_save(flags);
         cpu = raw_smp_processor_id();
         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
@@ -355,14 +362,6 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
         return ret;
 }
 
-static int trace_graph_thresh_entry(struct ftrace_graph_ent *trace)
-{
-        if (tracing_thresh)
-                return 1;
-        else
-                return trace_graph_entry(trace);
-}
-
 static void
 __trace_graph_function(struct trace_array *tr,
                 unsigned long ip, unsigned long flags, int pc)
@@ -457,7 +456,7 @@ static int graph_trace_init(struct trace_array *tr)
         set_graph_array(tr);
         if (tracing_thresh)
                 ret = register_ftrace_graph(&trace_graph_thresh_return,
-                                            &trace_graph_thresh_entry);
+                                            &trace_graph_entry);
         else
                 ret = register_ftrace_graph(&trace_graph_return,
                                             &trace_graph_entry);