Hi, steve, after some operations on file 'tracing_cpumask' and 'snapshot', trace ring buffer can no longer record anything. This series contain a patch to fix it and a constrived testcase to reproduce it. I think the reproduction testcase is useful to help others to check if their version has this problem and verify the bugfix. However, currently in "tools/testing/selftests/ftrace/test.d", there seems no appropriate subdirectory to put this kind reproductions. So I now put the testcase in "00basic" because it is basicly simple. Or would there be a new directory to collect simple reproduction testcases? Zheng Yejian (2): tracing: Fix cpu buffers unavailable due to 'record_disabled' messed selftests/ftrace: Add a basic testcase for snapshot kernel/trace/trace.c | 2 ++ .../ftrace/test.d/00basic/snapshot1.tc | 17 +++++++++++++++++ 2 files changed, 19 insertions(+) create mode 100644 tools/testing/selftests/ftrace/test.d/00basic/snapshot1.tc -- 2.25.1