Re: [PATCH v2 1/5] drm/ttm: Update Makefile for KUnit

[Karolina Stolarek <karolina.stolarek@intel.com>]

On 11.09.2023 12:49, Jani Nikula wrote:
> On Mon, 11 Sep 2023, Karolina Stolarek <karolina.stolarek@intel.com> wrote:
>> Update Makefile so it can produce a module that consists of TTM tests.
>> This will allow us to test non-exported functions when KUnit tests
>> are built as a module. Remove the tests' Makefile.
> 
> I'm asking questions instead of making assertions, because I'm not 100%
> confident, but I don't feel like this Makefile could work right.

Questions, assertions and comments are fine, I'm glad you're taking a 
look at the patch :) I'm not 100% confident either, so I welcome 
suggestions on how to improve it.

The problem is that TTM tests try to test symbols that are not exported, 
so I have to compile all the files together into one module if I choose 
to build KUnit tests as a module. The other option that I'm considering 
is to make the tests are builtin only. I'm tempted to go with it (for 
the sake of simplicity), but I'm trying to get the module option to work 
first.

> 
>>
>> Signed-off-by: Karolina Stolarek <karolina.stolarek@intel.com>
>> Reported-by: kernel test robot <lkp@intel.com>
>> Closes: https://lore.kernel.org/oe-kbuild-all/202309010358.50gYLkmw-lkp@intel.com/
>> Closes: https://lore.kernel.org/oe-kbuild-all/202309011134.bwvpuyOj-lkp@intel.com/
>> Closes: https://lore.kernel.org/oe-kbuild-all/202309011935.bBpezbUQ-lkp@intel.com/
>> ---
>>   drivers/gpu/drm/ttm/Makefile       | 18 +++++++++++++-----
>>   drivers/gpu/drm/ttm/tests/Makefile |  6 ------
>>   2 files changed, 13 insertions(+), 11 deletions(-)
>>   delete mode 100644 drivers/gpu/drm/ttm/tests/Makefile
>>
>> diff --git a/drivers/gpu/drm/ttm/Makefile b/drivers/gpu/drm/ttm/Makefile
>> index dad298127226..6322a33e65ed 100644
>> --- a/drivers/gpu/drm/ttm/Makefile
>> +++ b/drivers/gpu/drm/ttm/Makefile
>> @@ -2,10 +2,18 @@
>>   #
>>   # Makefile for the drm device driver.  This driver provides support for the
>>   
>> -ttm-y := ttm_tt.o ttm_bo.o ttm_bo_util.o ttm_bo_vm.o ttm_module.o \
>> -	ttm_execbuf_util.o ttm_range_manager.o ttm_resource.o ttm_pool.o \
>> -	ttm_device.o ttm_sys_manager.o
>> +ttm := ttm_tt.o ttm_bo.o ttm_bo_util.o ttm_bo_vm.o ttm_module.o \
>> +       ttm_execbuf_util.o ttm_range_manager.o ttm_resource.o ttm_pool.o \
>> +       ttm_device.o ttm_sys_manager.o
>> +obj-$(CONFIG_DRM_TTM) += $(ttm)
> 
> Does that not lead to each object in $(ttm) becoming its own module?

Huh, yes, that is what would happen here. Not good...

> 
>>   ttm-$(CONFIG_AGP) += ttm_agp_backend.o
> 
> Does this not create a ttm.o with just one object, depending on
> CONFIG_AGP?

I just left it as it was before my changes.

> 
>>   
>> -obj-$(CONFIG_DRM_TTM) += ttm.o
>> -obj-$(CONFIG_DRM_TTM_KUNIT_TEST) += tests/
>> +ttm-tests := tests/ttm_kunit_helpers.o tests/ttm_device_test.o \
>> +             tests/ttm_pool_test.o
> 
> I'd preserve the one object per line syntax. It's nicer for the diffs in
> subsequent updates.

OK, will update it in the next version (if such comes). I just followed 
the style of "ttm-y".

> 
>> +
>> +ifeq ($(CONFIG_DRM_TTM_KUNIT_TEST),m)
>> +    ttm-test-objs := $(ttm) $(ttm-tests)
> 
> Isn't the -objs syntax for host/userspace programs? And if not, doesn't
> it lead to objects with exported symbols being present in two places?

I saw it in use in other Makefiles, so I followed it. As for the 
exported symbols, I tested both builtin and module configs, and it was 
fine, but it's possible I missed something. I suspect that the variables 
are first expanded, and then processed by the Makefile.

Many thanks,
Karolina

> 
> Confused.
> 
> BR,
> Jani.
> 
>> +    obj-m := ttm-test.o
>> +else
>> +    obj-$(CONFIG_DRM_TTM_KUNIT_TEST) += $(ttm-tests)
>> +endif
>> diff --git a/drivers/gpu/drm/ttm/tests/Makefile b/drivers/gpu/drm/ttm/tests/Makefile
>> deleted file mode 100644
>> index ec87c4fc1ad5..000000000000
>> --- a/drivers/gpu/drm/ttm/tests/Makefile
>> +++ /dev/null
>> @@ -1,6 +0,0 @@
>> -# SPDX-License-Identifier: GPL-2.0 AND MIT
>> -
>> -obj-$(CONFIG_DRM_TTM_KUNIT_TEST) += \
>> -        ttm_device_test.o \
>> -        ttm_pool_test.o \
>> -        ttm_kunit_helpers.o
>