[PATCH v9 0/6] DRM scheduler kunit tests

[Tvrtko Ursulin]

There has repeatedly been quite a bit of apprehension when any change to the DRM
scheduler is proposed, with two main reasons being code base is considered
fragile, not well understood and not very well documented, and secondly the lack
of systematic testing outside the vendor specific tests suites and/or test
farms.

This series is an attempt to dislodge this status quo by adding some unit tests
using the kunit framework.

General approach is that there is a mock "hardware" backend which can be
controlled from tests, which in turn allows exercising various scheduler code
paths.

Only some simple basic tests get added in the series and hopefully it is easy to
understand what tests are doing.

An obligatory "screenshot" for reference:

[14:09:05] ============ drm_sched_basic_tests (3 subtests) ============
[14:09:06] [PASSED] drm_sched_basic_submit
[14:09:06] ================== drm_sched_basic_test  ===================
[14:09:06] [PASSED] A queue of jobs in a single entity
[14:09:06] [PASSED] A chain of dependent jobs across multiple entities
[14:09:06] [PASSED] Multiple independent job queues
[14:09:06] [PASSED] Multiple inter-dependent job queues
[14:09:07] ============== [PASSED] drm_sched_basic_test ===============
[14:09:07] [PASSED] drm_sched_basic_entity_cleanup
[14:09:07] ============== [PASSED] drm_sched_basic_tests ==============
[14:09:07] ======== drm_sched_basic_timeout_tests (1 subtest) =========
[14:09:08] [PASSED] drm_sched_basic_timeout
[14:09:08] ========== [PASSED] drm_sched_basic_timeout_tests ==========
[14:09:08] ======= drm_sched_basic_priority_tests (2 subtests) ========
[14:09:10] [PASSED] drm_sched_priorities
[14:09:10] [PASSED] drm_sched_change_priority
[14:09:10] ========= [PASSED] drm_sched_basic_priority_tests ==========
[14:09:10] ====== drm_sched_basic_modify_sched_tests (1 subtest) ======
[14:09:11] [PASSED] drm_sched_test_modify_sched
[14:09:11] ======= [PASSED] drm_sched_basic_modify_sched_tests ========
[14:09:11] ======== drm_sched_basic_credits_tests (1 subtest) =========
[14:09:12] [PASSED] drm_sched_test_credits
[14:09:12] ========== [PASSED] drm_sched_basic_credits_tests ==========
[14:09:12] ============================================================
[14:09:12] Testing complete. Ran 11 tests: passed: 11
[14:09:13] Elapsed time: 13.539s total, 0.001s configuring, 3.004s building, 10.462s running

v2:
 * Parameterize a bunch of similar tests.
 * Improve test commentary.
 * Rename TDR test to timeout. (Christian)
 * Improve quality and consistency of naming. (Philipp)

RFC v2 -> series v1:
 * Rebased for drm_sched_init changes.
 * Fixed modular build.
 * Added some comments.
 * Filename renames. (Philipp)

v2:
 * Dealt with a bunch of checkpatch warnings.

v3:
 * Some mock API renames, kerneldoc grammar fixes and indentation fixes.

v4:
 * Fix use after free caused by relying on scheduler fence for querying status.
 * Kerneldoc fixes.

v5:
 * Cleanup in-flight jobs on scheduler shutdown.
 * Change hang_limit to 1.

v6:
 * Use KUNIT_ASSERT_TRUE/FALSE.
 * Fixed patch titles.
 * Added credit_limit test.
 * Added CONFIG_DRM_SCHED_KUNIT_TEST_ASPIRATIONAL.

v7:
 * v6 omitted to send the first patch by mistake.

v8:
 * Removed CONFIG_DRM_SCHED_KUNIT_TEST_ASPIRATIONAL for now.
 * Added Christian's acks.

v9:
 * Fixed a potential memory leak caused by a race condition on mock scheduler
   shutdown. In order to reliably clean up everything, we have keep track of
   jobs even past the signalling stage, all until either DRM sched core managed
   to run the ->free_job() callback, or until mock scheduler teardown from the
   test.

Cc: Christian König <christian.koenig at amd.com>
Cc: Danilo Krummrich <dakr at kernel.org>
Cc: Matthew Brost <matthew.brost at intel.com>
Cc: Philipp Stanner <phasta at kernel.org>

Tvrtko Ursulin (6):
  drm: Move some options to separate new Kconfig
  drm/sched: Add scheduler unit testing infrastructure and some basic
    tests
  drm/sched: Add a simple timeout test
  drm/sched: Add basic priority tests
  drm/sched: Add a basic test for modifying entities scheduler list
  drm/sched: Add a basic test for checking credit limit

 drivers/gpu/drm/Kconfig                       | 109 +---
 drivers/gpu/drm/Kconfig.debug                 | 115 +++++
 drivers/gpu/drm/scheduler/.kunitconfig        |  12 +
 drivers/gpu/drm/scheduler/Makefile            |   2 +
 drivers/gpu/drm/scheduler/tests/Makefile      |   7 +
 .../gpu/drm/scheduler/tests/mock_scheduler.c  | 359 +++++++++++++
 drivers/gpu/drm/scheduler/tests/sched_tests.h | 226 +++++++++
 drivers/gpu/drm/scheduler/tests/tests_basic.c | 476 ++++++++++++++++++
 8 files changed, 1202 insertions(+), 104 deletions(-)
 create mode 100644 drivers/gpu/drm/Kconfig.debug
 create mode 100644 drivers/gpu/drm/scheduler/.kunitconfig
 create mode 100644 drivers/gpu/drm/scheduler/tests/Makefile
 create mode 100644 drivers/gpu/drm/scheduler/tests/mock_scheduler.c
 create mode 100644 drivers/gpu/drm/scheduler/tests/sched_tests.h
 create mode 100644 drivers/gpu/drm/scheduler/tests/tests_basic.c

-- 
2.48.0