Commit e447e1df authored Mar 12, 2009 by Steven Rostedt

tracing: explain why stack tracer is empty



If the stack tracing is disabled (by default) the stack_trace file
will only contain the header:

 # cat /debug/tracing/stack_trace
        Depth    Size      Location    (0 entries)
        -----    ----      --------

This can be frustrating to a developer that does not realize that the
stack tracer is disabled. This patch adds the following text:

  # cat /debug/tracing/stack_trace
        Depth    Size      Location    (0 entries)
        -----    ----      --------
 #
 #  Stack tracer disabled
 #
 # To enable the stack tracer, either add 'stacktrace' to the
 # kernel command line
 # or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'
 #

Signed-off-by: Steven Rostedt <srostedt@redhat.com>

parent 2da03ece

kernel/trace/trace_stack.c

+15 −0

Original line number	Diff line number	Diff line
		@@ -245,6 +245,17 @@ static int trace_lookup_stack(struct seq_file *m, long i)
		#endif
		}

		static void print_disabled(struct seq_file *m)
		{
		seq_puts(m, "#\n"
		"# Stack tracer disabled\n"
		"#\n"
		"# To enable the stack tracer, either add 'stacktrace' to the\n"
		"# kernel command line\n"
		"# or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'\n"
		"#\n");
		}

		static int t_show(struct seq_file m, void v)
		{
		long i;
		@@ -255,6 +266,10 @@ static int t_show(struct seq_file m, void v)
		" (%d entries)\n"
		" ----- ---- --------\n",
		max_stack_trace.nr_entries);

		if (!stack_tracer_enabled && !max_stack_size)
		print_disabled(m);

		return 0;
		}