On Wed, 29 May 2024 11:01:43 -0500 Tom Zanussi <tom.zanu...@linux.intel.com> wrote:
> Hi Masami, > > On Wed, 2024-05-29 at 08:38 +0900, Masami Hiramatsu wrote: > > On Wed, 29 May 2024 01:46:40 +0900 > > Masami Hiramatsu (Google) <mhira...@kernel.org> wrote: > > > > > On Mon, 27 May 2024 19:29:07 -0400 > > > Steven Rostedt <rost...@goodmis.org> wrote: > > > > > > > On Sun, 26 May 2024 19:10:57 +0900 > > > > "Masami Hiramatsu (Google)" <mhira...@kernel.org> wrote: > > > > > > > > > Hi, > > > > > > > > > > Here is a series of some fixes/improvements for the test > > > > > modules and boot > > > > > time selftest of kprobe events. I found a WARNING message with > > > > > some boot > > > > > time selftest configuration, which came from the combination of > > > > > embedded > > > > > kprobe generate API tests module and ftrace boot-time selftest. > > > > > So the main > > > > > problem is that the test module should not be built-in. But I > > > > > also think > > > > > this WARNING message is useless (because there are warning > > > > > messages already) > > > > > and the cleanup code is redundant. This series fixes those > > > > > issues. > > > > > > > > Note, when I enable trace tests as builtin instead of modules, I > > > > just > > > > disable the bootup self tests when it detects this. This helps > > > > with > > > > doing tests via config options than having to add user space code > > > > that > > > > loads modules. > > > > > > > > Could you do something similar? > > > > > > OK, in that case, I would like to move the test cleanup code in > > > module_exit function into the end of module_init function. > > > It looks there is no reason to split those into 2 parts. > > > > Wait, I would like to hear Tom's opinion. I found following usage > > comments > > in the code. > > > > * Following that are a few examples using the created events to test > > * various ways of tracing a synthetic event. > > * > > * To test, select CONFIG_SYNTH_EVENT_GEN_TEST and build the module. > > * Then: > > * > > * # insmod kernel/trace/synth_event_gen_test.ko > > * # cat /sys/kernel/tracing/trace > > * > > * You should see several events in the trace buffer - > > * "create_synth_test", "empty_synth_test", and several instances of > > * "gen_synth_test". > > * > > * To remove the events, remove the module: > > * > > * # rmmod synth_event_gen_test > > > > Tom, is that intended behavior ? and are you expected to reuse these > > events outside of the module? e.g. load the test module and run some > > test script in user space which uses those events? > > > > Yeah, this module was meant as a sample module showing how to create > and generate synthetic events in-kernel. > > So the interested user insmods the module, looks at the trace stream > and sees, ok the events are there as expected, so it does work, great, > let's remove the module to get rid of them and go write our own. > > Having both the creation and cleanup in module_init() wouldn't allow > the user the opportunity to do that i.e. verify the results by reading > the trace file. So, in summary, it is designed to be a module. Steve, I think these tests should be kept as modules. There are many reason to do so. - This test is designed to be used as module. - This can conflict with other boot time selftest if it is embedded. - We can make these tests and boot time selftest mutable exclusive but if we make these tests as modules, we can build and run both tests safely. - Embedding these tests leave new events when the kernel boot, which user must be cleaned up by manual. What would you think? Thank you, > > Tom > > > As far as I can see, those tests are not intended to be embedded in > > the > > kernel because those are expected to be removed. > > > > Thank you, > > > > > > > > Thank you, > > > > > > > > > > > -- Steve > > > > > > > > > > > > > > > > > > Thank you, > > > > > > > > > > --- > > > > > > > > > > Masami Hiramatsu (Google) (3): > > > > > tracing: Build event generation tests only as modules > > > > > tracing/kprobe: Remove unneeded WARN_ON_ONCE() in > > > > > selftests > > > > > tracing/kprobe: Remove cleanup code unrelated to selftest > > > > > > > > > > > > > > -- > > > Masami Hiramatsu (Google) <mhira...@kernel.org> > > > > > > -- Masami Hiramatsu (Google) <mhira...@kernel.org>
