Re: [Ksummit-discuss] [MAINTAINERS SUMMIT] & [TECH TOPIC] Improve regression tracking

[ebiederm@xmission.com (Eric W. Biederman)]

Shuah Khan <shuahkh@osg.samsung.com> writes:

> On 08/02/2017 11:33 AM, Eric W. Biederman wrote:
>> Shuah Khan <shuahkh@osg.samsung.com> writes:
>> 
>>> On 07/31/2017 10:54 AM, Eric W. Biederman wrote:
>>>> Steven Rostedt <rostedt@goodmis.org> writes:
>>>>
>>>>> On Wed, 5 Jul 2017 09:48:31 -0700
>>>>> Guenter Roeck <linux@roeck-us.net> wrote:
>>>>>
>>>>>> On 07/05/2017 08:27 AM, Steven Rostedt wrote:
>>>>>>> On Wed, 5 Jul 2017 08:16:33 -0700
>>>>>>> Guenter Roeck <linux@roeck-us.net> wrote:  
>>>>>> [ ... ]
>>>>>>>>
>>>>>>>> If we start shaming people for not providing unit tests, all we'll accomplish is
>>>>>>>> that people will stop providing bug fixes.  
>>>>>>>
>>>>>>> I need to be clearer on this. What I meant was, if there's a bug
>>>>>>> where someone has a test that easily reproduces the bug, then if
>>>>>>> there's not a test added to selftests for said bug, then we should
>>>>>>> shame those into doing so.
>>>>>>>   
>>>>>>
>>>>>> I don't think that public shaming of kernel developers is going to work
>>>>>> any better than public shaming of children or teenagers.
>>>>>>
>>>>>> Maybe a friendlier approach would be more useful ?
>>>>>
>>>>> I'm a friendly shamer ;-)
>>>>>
>>>>>>
>>>>>> If a test to reproduce a problem exists, it might be more beneficial to suggest
>>>>>> to the patch submitter that it would be great if that test would be submitted
>>>>>> as unit test instead of shaming that person for not doing so. Acknowledging and
>>>>>> praising kselftest submissions might help more than shaming for non-submissions.
>>>>>>
>>>>>>> A bug that is found by inspection or hard to reproduce test cases are
>>>>>>> not applicable, as they don't have tests that can show a regression.
>>>>>>>   
>>>>>>
>>>>>> My concern would be that once the shaming starts, it won't stop.
>>>>>
>>>>> I think this is a communication issue. My word for "shaming" was to
>>>>> call out a developer for not submitting a test. It wasn't about making
>>>>> fun of them, or anything like that. I was only making a point
>>>>> about how to teach people that they need to be more aware of the
>>>>> testing infrastructure. Not about actually demeaning people.
>>>>>
>>>>> Lets take a hypothetical sample. Say someone posted a bug report with
>>>>> an associated reproducer for it. The developer then runs the reproducer
>>>>> sees the bug, makes a fix and sends it to Linus and stable. Now the
>>>>> developer forgets this and continues on their merry way. Along comes
>>>>> someone like myself and sees a reproducing test case for a bug, but
>>>>> sees no test added to kselftests. I would send an email along the lines
>>>>> of "Hi, I noticed that there was a reproducer for this bug you fixed.
>>>>> How come there was no test added to the kselftests to make sure it
>>>>> doesn't appear again?" There, I "shamed" them ;-)
>>>>
>>>> I just want to point out that kselftests are hard to build and run.
>>>>
>>>> As I was looking at another issue I found a bug in one of the tests.  It
>>>> had defined a constant wrong.  I have a patch.  It took me a week of
>>>> poking at the kselftest code and trying one thing or another (between
>>>> working on other things) before I could figure out which combination of
>>>> things would let the test build and run.
>>>>
>>>> Until kselftests get easier to run I don't think they are something we
>>>> want to push to hard.
>>>>
>>>
>>> I would say it is easy to run ksefltests - "make kseflttest" from the
>>> main Makefile does this for you. You can also run individual tests:
>> 
>> On 4.13-rc1  That doesn't work.
>> 
>> $ make O=$PWD-build -j8 kselftests
>> make[1]: Entering directory 'linux-build'
>> make[1]: *** No rule to make target 'kselftests'.  Stop.
>> make[1]: Leaving directory 'linux-build'
>> Makefile:145: recipe for target 'sub-make' failed
>> make: *** [sub-make] Error 2
>
> It is "make kselftest"

If I include the standard O= to keep my source tree pristine
it still fails.  Which is a practical issue.  Especially because
that "make kselftest" needs to be followed by I think "make mrproper"
to get back to my normal development workflow.

I don't remember exactly what the issue was but I could not get:
tools/testing/selftests/x86/mpx-mini-test.c
tools/testing/selftests/x86/protection_keys.c

to build let alone run when I did "make kselftest"

>> And why I have to use some esoteric command and not just the
>> traditional "make path/to/test/output" to run an individual
>> test is beyond me.
>> 
>
> make kselftest from top level Makefile is a way to run all the tests.
> As I mentioned in my previous email 
>
> "You can also run individual tests:
>
> "make -C tools/testing/selftests/sync" for example to run sync tests.
>
> or you can also run:
>
> make -C tools/testing/selftests/ run_tests

As I said complicated.  That is definitely not the ordinary way of
building things in the kernel tree.

Given that some of those other tests take a little while to run, running
individual tests is actually quite important during development.

Eric