From e447e1df2e568cd43d1918963c9f09fae85aea57 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 12 Mar 2009 19:42:29 -0400 Subject: [PATCH] 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 --- kernel/trace/trace_stack.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index 4564fd94b0cd..91ccbf396c9a 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -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; } -- 2.39.5