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authorSteven Rostedt <srostedt@redhat.com>2009-03-12 19:42:29 -0400
committerSteven Rostedt <srostedt@redhat.com>2009-03-12 21:15:01 -0400
commite447e1df2e568cd43d1918963c9f09fae85aea57 (patch)
treea73edfcc1b603a921ed7e332ce614e1345385100 /kernel/trace/trace_stack.c
parent2da03ecee6308ea174e8a02b92a3c4ec92e886c8 (diff)
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>
Diffstat (limited to 'kernel/trace/trace_stack.c')
-rw-r--r--kernel/trace/trace_stack.c15
1 files changed, 15 insertions, 0 deletions
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;
}