[PATCH 0/2] Input: discard pre-registration events and test state seeding

[Karlos Abel <kabel@voidship.net>]

This series prevents input handlers from receiving buffered initialization
events after device registration. On a ThinkPad T14 Gen 6, a later LED
update flushed a stale SW_RFKILL_ALL event seeded by thinkpad_acpi.
The fix drops the pending events and their timestamp before handlers
attach, while retaining the seeded switch and absolute-axis state.

Patch 1 contains the six-line runtime fix. Patch 2 adds KUnit coverage for
registration with and without event-buffer resizing. The test uses a
virtual SW_DOCK device and performs no real radio operations.

Tested on mainline 3857c2fe5449541e24afc5efdb0f81a8a8f9a3a0 (7.3.0-rc6):
 - Tests alone on the unmodified input core: four pass, two fail.
   The non-resizing case replays one stale switch event; both cases
   retain the initialization timestamp.
 - Patch 1 alone: all four existing input-core tests pass.
 - Both patches: all six input-core tests pass.
Both source commits were built and tested under UML without compiler
warnings. The final files match the earlier failing/passing comparison.

The same runtime fix was also tested with QEMU/KVM on Arch 7.2.7 and on
the ThinkPad.

AI assistance: OpenAI Codex assisted source analysis, the fix, regression
tests and this text. The submitter performed the physical hardware
comparisons.

Karlos Abel (2):
  Input: discard pre-registration events before attaching handlers
  Input: test state seeding across device registration

 drivers/input/input.c            |   6 ++
 drivers/input/tests/input_test.c | 168 +++++++++++++++++++++++++++++++
 2 files changed, 174 insertions(+)


base-commit: 3857c2fe5449541e24afc5efdb0f81a8a8f9a3a0