On Fri, 24 Aug 2018 22:41:22 -0400 Steven Rostedt rostedt@goodmis.org wrote:
On Sat, 25 Aug 2018 10:45:09 +0900 Masami Hiramatsu mhiramat@kernel.org wrote:
On Fri, 24 Aug 2018 19:23:52 -0400 Steven Rostedt rostedt@goodmis.org wrote:
On Fri, 17 Aug 2018 01:40:30 +0900 Masami Hiramatsu mhiramat@kernel.org wrote:
Add a testcase for max stack tracer, which checks basic max stack usage tracing and its filter feature.
Signed-off-by: Masami Hiramatsu mhiramat@kernel.org
.../ftrace/test.d/ftrace/func_stack_tracer.tc | 39 ++++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100644 tools/testing/selftests/ftrace/test.d/ftrace/func_stack_tracer.tc
diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/func_stack_tracer.tc b/tools/testing/selftests/ftrace/test.d/ftrace/func_stack_tracer.tc new file mode 100644 index 000000000000..b414f0e3c646 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/ftrace/func_stack_tracer.tc @@ -0,0 +1,39 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: ftrace - Max stack tracer +# Test the basic function of max-stack usage tracing
+if [ ! -f stack_trace ]; then
- echo "Max stack tracer is not supported - please make CONFIG_STACK_TRACER=y"
- exit_unsupported
+fi
+echo > stack_trace_filter +echo 0 > stack_max_size +echo 1 > /proc/sys/kernel/stack_tracer_enabled
+: "Fork and wait for the first entry become !lock" +timeout=10 +while [ $timeout -ne 0 ]; do
- ( echo "forked" )
- FL=`grep " 0)" stack_trace`
- echo $FL | grep -q "lock" || break;
- timeout=$((timeout - 1))
+done +echo 0 > /proc/sys/kernel/stack_tracer_enabled
+echo '*lock*' > stack_trace_filter +test `cat stack_trace_filter | wc -l` -eq `grep lock stack_trace_filter | wc -l`
+echo 0 > stack_max_size +echo 1 > /proc/sys/kernel/stack_tracer_enabled
This test fails quite a bit because it doesn't guarantee that another stack trace gets in that is bigger, and we don't find the "lock".
Hmm, maybe I misunderstand what is the stack_trace_filter. I thought it filtered the function that triggered stack trace, so the top of stack trace was always filtered function. If not, what does this filter?
Ah, I missed the filter part, no its correct, and actually found a bug ;-) By adding this patch, it works again:
Great! this shows ftracetest really works :) Anyway, with this fix, we don't need the timeout things anymore.
Thanks!
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index 4237eba4ef20..2b0d1ee3241c 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -111,7 +111,7 @@ check_stack(unsigned long ip, unsigned long *stack) stack_trace_max_size = this_size; stack_trace_max.nr_entries = 0;
- stack_trace_max.skip = 3;
- stack_trace_max.skip = 0;
save_stack_trace(&stack_trace_max);
-- Steve
+: "Fork and always the first entry including lock" +timeout=10 +while [ $timeout -ne 0 ]; do
- ( echo "forked" )
- FL=`grep " 0)" stack_trace`
- echo $FL | grep -q "lock"
- timeout=$((timeout - 1))
+done +echo 0 > /proc/sys/kernel/stack_tracer_enabled