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

[changbin . du]

From: Changbin Du <changbin...@intel.com>

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...@intel.com>
---
 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