Re: [PATCH v2 2/2] drm/tests: Change "igt_" prefix to "test_drm_"

[Jani Nikula]

On Fri, 02 Sep 2022, Maxime Ripard <maxime@xxxxxxxxxx> wrote:
> On Fri, Sep 02, 2022 at 11:04:14AM +0300, Jani Nikula wrote:
>> On Thu, 01 Sep 2022, Maíra Canal <mairacanal@xxxxxxxxxx> wrote:
>> > Hi Maxime,
>> >
>> > On 9/1/22 09:55, Maxime Ripard wrote:
>> >> Hi,
>> >> 
>> >> On Thu, Sep 01, 2022 at 09:42:10AM -0300, Maíra Canal wrote:
>> >>> With the introduction of KUnit, IGT is no longer the only option to run
>> >>> the DRM unit tests, as the tests can be run through kunit-tool or on
>> >>> real hardware with CONFIG_KUNIT.
>> >>>
>> >>> Therefore, remove the "igt_" prefix from the tests and replace it with
>> >>> the "test_drm_" prefix, making the tests' names independent from the tool
>> >>> used.
>> >>>
>> >>> Signed-off-by: Maíra Canal <mairacanal@xxxxxxxxxx>
>> >>>
>> >>> ---
>> >>> v1 -> v2: https://lore.kernel.org/dri-devel/20220830211603.191734-1-mairacanal@xxxxxxxxxx/
>> >>> - Change "drm_" prefix to "test_drm_", as "drm_" can be a bit confusing (Jani Nikula).
>> >> 
>> >> I appreciate it's a bit of a bikeshed but I disagree with this. The
>> >> majority of the kunit tests already out there start with the framework
>> >> name, including *all* the examples in the kunit doc. Plus, it's fairly
>> >> obvious that it's a test, kunit is only about running tests in the first
>> >> place.
>> >
>> > Would it be better to keep it as "drm_"?
>> 
>> That's not "keeping". That's renaming igt to drm.
>
> Well, there's like half the tests that are prefixed with drm, the other
> with igt, so it's both really
>
>> > Currently, I don't think it is appropriate to hold the "igt_" prefix, as
>> > the tests are not IGT exclusive, but I don't have a strong opinion on
>> > using the "drm_" or the "test_drm" prefixes.
>> 
>> I repeat my stance that "drm_" alone is confusing.
>
> What are you confusing it with?
>
>> For the reason alone that it pollutes the code tagging tools, mixing
>> actual drm_ types and functions with unit test functions.
>
> I don't get it, I'm sorry. All these functions are static and not part
> of any API, so I can't see how it would pollute a code tagging tool. Or
> at least, not more than any driver does.
>
> And we're part of a larger project here, it's about consistency with the
> rest of the ecosystem.

Okay, so I'm just going to explain what I mean, but say "whatever" right
after and move on.

For example, drm_buddy_test.c includes drm_buddy.h so with the igt_ ->
drm_ rename none of the test functions may clash with the drm_buddy_
prefixed existing functions. Ditto for all tests similarly.

For example drm_buddy_alloc_range() as a name sounds like something that
allocs a range, not something that tests range allocation. On the other
hand, you have drm_buddy_alloc_blocks() which is actually a real
drm_buddy function, not a test. What would you call a test that tests
that? Here, we end up with names that are all prefixed drm_buddy and you
won't know what's the actual function and what's the test unless you
look it up.

I use code tagging that I can use for finding and completing
e.g. functions. Currently I have the following completions, for
igt_buddy_ and drm_buddy_, respectively:

Possible completions are:
igt_buddy_alloc_limit 	igt_buddy_alloc_optimistic 	igt_buddy_alloc_pathological
igt_buddy_alloc_pessimistic 	igt_buddy_alloc_range 	igt_buddy_alloc_smoke

Possible completions are:
drm_buddy_alloc_blocks 	drm_buddy_block 	drm_buddy_block_is_allocated 	drm_buddy_block_is_free
drm_buddy_block_is_split 	drm_buddy_block_offset 	drm_buddy_block_order 	drm_buddy_block_print
drm_buddy_block_size 	drm_buddy_block_state 	drm_buddy_block_trim 	drm_buddy_fini
drm_buddy_free_block 	drm_buddy_free_list 	drm_buddy_init 	drm_buddy_init_test
drm_buddy_module_exit 	drm_buddy_module_init 	drm_buddy_print

With the patch at hand, they'll all be lumped under drm_buddy_
completions, and some of them will be actual drm buddy functions and
some not.

I just find it a very odd convention to name the tests in a way that's
indistinguishable from the real things. Even *within* drm_buddy_test.c
where you read the test code. Because currently you do have calls to
igt_buddy_ prefixed functions from other igt_buddy_ prefixed functions,
along with the drm_buddy_ prefixed calls. I think it's just going to be
a mess.

/rant

Whatever. Moving on.


BR,
Jani.


-- 
Jani Nikula, Intel Open Source Graphics Center