[PATCH v4 3/4] ftrace: Have funcgraph-args take affect during tracing
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2025-02-27 18:57:39
Also in:
bpf, lkml
Subsystem:
the rest, tracing · Maintainers:
Linus Torvalds, Steven Rostedt, Masami Hiramatsu
From: Steven Rostedt <rostedt@goodmis.org> Currently, when function_graph is started, it looks at the option funcgraph-args, and if it is set, it will enable tracing of the arguments. But if tracing is already running, and the user enables funcgraph-args, it will have no effect. Instead, it should enable argument tracing when it is enabled, even if it means disabling the function graph tracing for a short time in order to do the transition. Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> --- kernel/trace/trace_functions_graph.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 5049fe25ceef..71b2fb068b6b 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c@@ -464,7 +464,7 @@ static int graph_trace_init(struct trace_array *tr) else tr->gops->retfunc = trace_graph_return; - /* Make gops functions are visible before we start tracing */ + /* Make gops functions visible before we start tracing */ smp_mb(); ret = register_ftrace_graph(tr->gops);
@@ -475,6 +475,28 @@ static int graph_trace_init(struct trace_array *tr) return 0; } +static int ftrace_graph_trace_args(struct trace_array *tr, int set) +{ + trace_func_graph_ent_t entry; + + if (set) + entry = trace_graph_entry_args; + else + entry = trace_graph_entry; + + /* See if there's any changes */ + if (tr->gops->entryfunc == entry) + return 0; + + unregister_ftrace_graph(tr->gops); + + tr->gops->entryfunc = entry; + + /* Make gops functions visible before we start tracing */ + smp_mb(); + return register_ftrace_graph(tr->gops); +} + static void graph_trace_reset(struct trace_array *tr) { tracing_stop_cmdline_record();
@@ -1607,6 +1629,9 @@ func_graph_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set) if (bit == TRACE_GRAPH_GRAPH_TIME) ftrace_graph_graph_time_control(set); + if (bit == TRACE_GRAPH_ARGS) + return ftrace_graph_trace_args(tr, set); + return 0; }
--
2.47.2