On Tue, 30 Jul 2019 22:08:50 +0800
Changbin Du <[email protected]> wrote:
> We already have tested it before. The second one should be removed.
> With this change, the performance should have little improvement.
>
> Fixes: 9cd2992f2d6c ("fgraph: Have set_graph_notrace only affect
> function_graph tracer")
Thanks! I think this should even be marked for stable. Not really a bad
bug, but a bug none the less.
-- Steve
> Signed-off-by: Changbin Du <[email protected]>
> ---
> kernel/trace/trace_functions_graph.c | 17 +++++++----------
> 1 file changed, 7 insertions(+), 10 deletions(-)
>
> diff --git a/kernel/trace/trace_functions_graph.c
> b/kernel/trace/trace_functions_graph.c
> index 69ebf3c2f1b5..78af97163147 100644
> --- a/kernel/trace/trace_functions_graph.c
> +++ b/kernel/trace/trace_functions_graph.c
> @@ -137,6 +137,13 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
> 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);
> /*
> @@ -155,16 +162,6 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
> if (ftrace_graph_ignore_irqs())
> 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.
