From: Steven Rostedt <rostedt@xxxxxxxxxxx> 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. Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Sven Schnelle <svens@xxxxxxxxxxxxx> Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx> Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx> Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx> Cc: Guo Ren <guoren@xxxxxxxxxx> Cc: Donglin Peng <dolinux.peng@xxxxxxxxx> Cc: Zheng Yejian <zhengyejian@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/20241223201542.240760965@xxxxxxxxxxx Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> --- 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 406b21472bde..49fcf665cb58 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -462,7 +462,7 @@ 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); @@ -473,6 +473,28 @@ 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(); @@ -1605,6 +1627,9 @@ 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
