fgraph: Have set_graph_notrace only affect function_graph tracer

In order to make the function graph infrastructure more generic, there can
not be code specific for the function_graph tracer in the generic code. This
includes the set_graph_notrace logic, that stops all graph calls when a
function in the set_graph_notrace is hit.

By using the trace_recursion mask, we can use a bit in the current
task_struct to implement the notrace code, and move the logic out of
fgraph.c and into trace_functions_graph.c and keeps it affecting only the
tracer and not all call graph callbacks.

Acked-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index b846d82c2f95..ecf543df943b 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -188,6 +188,18 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
         int cpu;
         int pc;
 
+        if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT))
+                return 0;
+
+        if (ftrace_graph_notrace_addr(trace->func)) {
+                trace_recursion_set(TRACE_GRAPH_NOTRACE_BIT);
+                /*
+                 * Need to return 1 to have the return called
+                 * that will clear the NOTRACE bit.
+                 */
+                return 1;
+        }
+
         if (!ftrace_trace_task(tr))
                 return 0;
 
@@ -290,6 +302,11 @@ void trace_graph_return(struct ftrace_graph_ret *trace)
 
         ftrace_graph_addr_finish(trace);
 
+        if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
+                trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
+                return;
+        }
+
         local_irq_save(flags);
         cpu = raw_smp_processor_id();
         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
@@ -315,6 +332,11 @@ static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
 {
         ftrace_graph_addr_finish(trace);
 
+        if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
+                trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
+                return;
+        }
+
         if (tracing_thresh &&
             (trace->rettime - trace->calltime < tracing_thresh))
                 return;