[PATCH 5.2 082/131] fgraph: Remove redundant ftrace_graph_notrace_addr() test

From: Greg Kroah-Hartman
Date: Mon Aug 05 2019 - 09:25:01 EST


From: Changbin Du <changbin.du@xxxxxxxxx>

commit 6c77221df96177da0520847ce91e33f539fb8b2d upstream.

We already have tested it before. The second one should be removed.
With this change, the performance should have little improvement.

Link: http://lkml.kernel.org/r/20190730140850.7927-1-changbin.du@xxxxxxxxx

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 9cd2992f2d6c ("fgraph: Have set_graph_notrace only affect function_graph tracer")
Signed-off-by: Changbin Du <changbin.du@xxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
kernel/trace/trace_functions_graph.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)

--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -137,6 +137,13 @@ int trace_graph_entry(struct ftrace_grap
if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT))
return 0;

+ /*
+ * Do not trace a function if it's filtered by set_graph_notrace.
+ * Make the index of ret stack negative to indicate that it should
+ * ignore further functions. But it needs its own ret stack entry
+ * to recover the original index in order to continue tracing after
+ * returning from the function.
+ */
if (ftrace_graph_notrace_addr(trace->func)) {
trace_recursion_set(TRACE_GRAPH_NOTRACE_BIT);
/*
@@ -156,16 +163,6 @@ int trace_graph_entry(struct ftrace_grap
return 0;

/*
- * Do not trace a function if it's filtered by set_graph_notrace.
- * Make the index of ret stack negative to indicate that it should
- * ignore further functions. But it needs its own ret stack entry
- * to recover the original index in order to continue tracing after
- * returning from the function.
- */
- 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.
*/