Re: [PATCH v9 00/53] fix CONFIG_DRM_USE_DYNAMIC_DEBUG=y

jim.cromie
2024-07-13T21:45:24Z

On Fri, Jul 12, 2024 at 9:44 AM Łukasz Bartosik <ukaszb@chromium.org> wrote:
>
> On Wed, Jul 3, 2024 at 12:14 AM <jim.cromie@gmail.com> wrote:
> >
> > On Tue, Jul 2, 2024 at 4:01 PM Luis Chamberlain <mcgrof@kernel.org> wrote:
> > >
> > > On Tue, Jul 02, 2024 at 03:56:50PM -0600, Jim Cromie wrote:
> > > > This fixes dynamic-debug support for DRM.debug, added via classmaps.
> > > > commit bb2ff6c27bc9 (drm: Disable dynamic debug as broken)
> > > >
> > > > CONFIG_DRM_USE_DYNAMIC_DEBUG=y was marked broken because drm.debug=val
> > > > was applied when drm.ko was modprobed; too early for the yet-to-load
> > > > drivers, which thus missed the enablement. My testing with
> > > > /etc/modprobe.d/ entries and modprobes with dyndbg=$querycmd options
> > > > obscured this omission.
> > > >
> > > > The fix is to replace invocations of DECLARE_DYNDBG_CLASSMAP with
> > > > DYNDBG_CLASSMAP_DEFINE for core, and DYNDBG_CLASSMAP_USE for drivers.
> > > > The distinction allows dyndbg to also handle the users properly.
> > > >
> > > > DRM is the only current classmaps user, and is not really using it,
> > > > so if you think DRM could benefit from zero-off-cost debugs based on
> > > > static-keys, please test.
> > > >
> > > > HISTORY
> > > >
> > > > 9/4/22 - ee879be38bc8..ace7c4bbb240 commited - classmaps-v1 dyndbg parts
> > > > 9/11/22 - 0406faf25fb1..16deeb8e18ca commited - classmaps-v1 drm parts
> > > >
> > > > https://lore.kernel.org/lkml/Y3XUrOGAV4I7bB3M@kroah.com/
> > > > greg k-h says:
> > > > This should go through the drm tree now. The rest probably should also
> > > > go that way and not through my tree as well.
> > >
> > > Can't this just be defined as a coccinelle smpl patch? Must easier
> > > to read than 53 patches?
> > >
> >
> > perhaps it could - Im not sure that would be easier to review
> > than a file-scoped struct declaration or reference per driver
> >
> > Also, I did it hoping to solicit more Tested-by:s with drm.debug=0x1ff
> >
> > Jim
> >
>
> Jim,
>
> When testing different combinations of Y/M for TEST_DYNAMIC_DEBUG and
> TEST_DYNAMIC_DEBUG_SUBMOD in virtme-ng I spotted test failures:
>
> When the TEST_DYNAMIC_DEBUG=M and TEST_DYNAMIC_DEBUG_SUBMOD=M -
> BASIC_TESTS, COMMA_TERMINATOR_TESTS, TEST_PERCENT_SPLITTING,
> TEST_MOD_SUBMOD selftests passed
> When the TEST_DYNAMIC_DEBUG=Y and TEST_DYNAMIC_DEBUG_SUBMOD=M -
> BASIC_TESTS, COMMA_TERMINATOR_TESTS selftests passed, however
> TEST_PERCENT_SPLITTING selftest fails with ": ./dyndbg_selftest.sh:270
> check failed expected 1 on =pf, got 0"
> When the TEST_DYNAMIC_DEBUG=Y and TEST_DYNAMIC_DEBUG_SUBMOD=Y -
> BASIC_TESTS, COMMA_TERMINATOR_TESTS selftests passed, however
> TEST_PERCENT_SPLITTING selftest fails also with ":
> ./dyndbg_selftest.sh:270 check failed expected 1 on =pf, got 0"
>
> Have I missed something ?
>

I am not seeing those 2 failures on those 2 configs.

most of my recent testing has been on x86-defconfig + minimals,
built and run using/inside virtme-ng

the last kernel I installed on this hw was june 16, I will repeat that,
and report soon if I see the failure outside the vm

I'll also send you my script, to maybe speed isolation of the differences.

> Thanks,
> Lukasz
>
> > > Luis
> > >