Messages in this thread | | | Date | Tue, 30 Jul 2019 12:15:27 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH] fgraph: Remove redundant ftrace_graph_notrace_addr() test |
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On Tue, 30 Jul 2019 22:08:50 +0800 Changbin Du <changbin.du@gmail.com> 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 <changbin.du@gmail.com> > --- > 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.
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