[PATCH] perf ftrace: Add -O option to set trace option

[changbin . du]

From: Changbin Du <changbin.du@xxxxxxxxx>

There are some trace options to control what gets printed in the trace
output or manipulate the tracers. This patch add a commandline option
to set it.

Example:
perf ftrace -t function -O noprint-parent --trace-funcs "__kmalloc" -a
            Xorg-1874  [002] ....  4107.182911: __kmalloc
            Xorg-1874  [002] ....  4107.182920: __kmalloc

perf ftrace -t function -O print-parent --trace-funcs "__kmalloc" -a
            Xorg-1874  [000] ....  3924.917243: __kmalloc <-drm_atomic_state_init
            Xorg-1874  [000] ....  3924.917251: __kmalloc <-drm_atomic_state_init

Signed-off-by: Changbin Du <changbin.du@xxxxxxxxx>
---
 tools/perf/builtin-ftrace.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 25a42ac..8b473e2 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -36,6 +36,7 @@ struct perf_ftrace {
 	struct list_head	graph_funcs;
 	struct list_head	nograph_funcs;
 	int			graph_depth;
+	const char		*trace_option;
 };
 
 struct filter_entry {
@@ -261,6 +262,17 @@ static int set_tracing_depth(struct perf_ftrace *ftrace)
 	return 0;
 }
 
+static int set_tracing_option(struct perf_ftrace *ftrace)
+{
+	if (ftrace->trace_option == NULL)
+		return 0;
+
+	if (write_tracing_file("trace_options", ftrace->trace_option) < 0)
+		return -1;
+
+	return 0;
+}
+
 static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
 {
 	char *trace_file;
@@ -313,6 +325,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
 		goto out_reset;
 	}
 
+	if (set_tracing_option(ftrace) < 0) {
+		pr_err("failed to set trace option\n");
+		goto out_reset;
+	}
+
 	if (write_tracing_file("current_tracer", ftrace->tracer) < 0) {
 		pr_err("failed to set current_tracer to %s\n", ftrace->tracer);
 		goto out_reset;
@@ -456,6 +473,8 @@ int cmd_ftrace(int argc, const char **argv)
 		     "Set nograph filter on given functions", parse_filter_func),
 	OPT_INTEGER('D', "graph-depth", &ftrace.graph_depth,
 		    "Max depth for function graph tracer"),
+	OPT_STRING('O', "trace-option", &ftrace.trace_option, "option",
+		   "Set a trace option"),
 	OPT_END()
 	};
 
-- 
2.7.4