Hi Janusz,
throughout the series you modify the code right after
introducing it. How about changing the order of things a bit:
1) order the functions in a symmetrical way between
register/unregister steps and group them as you see necessary,
(At that point you would not be fixing the issue yet, but
prepare the code for further changes)
2) then introduce the new flag along with all the labels needed
for clean unregistration.
I think that way you could reduce number of patches (and changes
in code needing review) while also fixing the original issue.
Overall, I believe this is a good effort and much needed change
in registration and unregistering process.
Best Regards,
Krzysztof
> Starting with commit ec3e00b4ee27 ("drm/i915: stop registering if
> drm_dev_register() fails"), we may return from i915_driver_register()
> immediately, skipping remaining registration steps. However, the
> _unregister() counterpart called at device remove knows nothing about that
> skip and executes reverts of all those steps. As a consequence, a number
> of kernel warnings that taint the kernel are triggered.
>
> Introduce a flag that indicates device registration status and raise it on
> device registration success. As a minimum (first patch), when that flag
> is found not set while unregistering the driver, jump over those reverts
> of registration steps omitted after device registration failure that are
> not ready for being called unconditionally (and trigger the kernel
> warnings).
>
> With the second patch, also jump over reverts of other driver registration
> steps that were not called due to device registration failure. Some
> unregister function calls, found implementing additional steps beyond the
> register reverts, are still executed.
>
> To simplify i915_driver_unregister() code, the third patch makes sure
> reverts of driver registration steps executed before potentially
> unsuccessful device registration are symmetrically called after
> the device unplug.
>
> Finally, the last patch further simplifies the i915_driver_unregister()
> code by moving two required steps down, right after device unplug.
>
> The first patch may be squashed with one or more of its follow-ups if so
> decided.
>
> Janusz Krzysztofik (4):
> drm/i915: Skip harmful unregister steps if not registered
> drm/i915: Omit unnecessary driver unregister steps
> drm/i915: Fix asymmetry in PMU register/unregister step order
> drm/i915: Group not skipped unregister steps
>
> drivers/gpu/drm/i915/gt/intel_gt.c | 6 ++++++
> drivers/gpu/drm/i915/i915_driver.c | 18 ++++++++++++------
> drivers/gpu/drm/i915/i915_drv.h | 2 ++
> 3 files changed, 20 insertions(+), 6 deletions(-)
>
> --
> 2.48.1
>
