[PATCH v4 3/3] tracing/ftrace: Add support to record and display tgid

From: Joel Fernandes
Date: Mon Jun 26 2017 - 01:39:38 EST


Make function tracer able to record tgid if/when record-tgid is enabled.

Cc: kernel-team@xxxxxxxxxxx
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Tested-by: Michael Sartain <mikesart@xxxxxxxxx>
Signed-off-by: Joel Fernandes <joelaf@xxxxxxxxxx>
---
kernel/trace/trace_functions.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)

diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index a3bddbfd0874..d6bdc38ab273 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -27,6 +27,7 @@ static void
function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct pt_regs *pt_regs);
static struct tracer_flags func_flags;
+static bool tgid_recorded;

/* Our option */
enum {
@@ -104,6 +105,11 @@ static int function_trace_init(struct trace_array *tr)
put_cpu();

tracing_start_cmdline_record();
+
+ if (tr->trace_flags & TRACE_ITER_RECORD_TGID) {
+ tgid_recorded = true;
+ tracing_start_tgid_record();
+ }
tracing_start_function_trace(tr);
return 0;
}
@@ -112,6 +118,10 @@ static void function_trace_reset(struct trace_array *tr)
{
tracing_stop_function_trace(tr);
tracing_stop_cmdline_record();
+ if (tgid_recorded) {
+ tracing_stop_tgid_record();
+ tgid_recorded = false;
+ }
ftrace_reset_array_ops(tr);
}

@@ -252,6 +262,21 @@ func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
return 0;
}

+static int
+func_tracer_flag_changed(struct trace_array *tr, unsigned int mask,
+ int enabled)
+{
+ if (mask == TRACE_ITER_RECORD_TGID) {
+ tgid_recorded = !!enabled;
+ if (enabled)
+ tracing_start_tgid_record();
+ else
+ tracing_stop_tgid_record();
+ }
+
+ return 0;
+}
+
static struct tracer function_trace __tracer_data =
{
.name = "function",
@@ -260,6 +285,7 @@ static struct tracer function_trace __tracer_data =
.start = function_trace_start,
.flags = &func_flags,
.set_flag = func_set_flag,
+ .flag_changed = func_tracer_flag_changed,
.allow_instances = true,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_function,
--
2.13.1.611.g7e3b11ae1-goog