[PATCH v8 0/1 i-g-t] tests: Add a new test for driver/device hot reload

[Janusz Krzysztofik]

The test should help resolving driver bugs which exhibit themselves
when a device is unplugged / driver unbind from a device while the
device is busy (different from simple module unload which requires 
device references being put first).

Janusz Krzysztofik (1):
  tests: Add a new test for driver/device hot reload

 tests/Makefile.sources  |   1 +
 tests/core_hot_reload.c | 408 ++++++++++++++++++++++++++++++++++++++++
 tests/meson.build       |   1 +
 3 files changed, 410 insertions(+)
 create mode 100644 tests/core_hot_reload.c

Changelog:
v7->v8:
- move workload functions back from fixture to subtests,
- register different actions and different workloads in respective
  tables and iterate over those tables while enumerating subtests,
- introduce new subtest flavors by simply omiting module unload step,
- instead of simply requesting bus rescan or not, introduce action
  specific device recovery helpers, required specifically with those
  new subtests not touching the module,
- split workload functions in two parts, one spawning the workload,
  the other waiting for its completion,
- for the new subtests not requiring module unload, run workload
  functions directly from the test process and use new workload
  completion wait functions in place of subprocess completion wait,
- take more control over logging, longjumps and exit codes in
  workload subprocesses,
- add some debug messages for easy progress watching,
- move function API descriptions on top of respective typedefs,
- drop patch 2/2 with external workload command again, still nobody
  likes it.

v6->v7:
- add missing igt_exit() needed with the second patch.

v5->v6 (third public submission, incorrectly marked as v5, sorry):
- run workload inside an igt helper subprocess so resources consumed
  by the workload are cleaned up automatically on workload subprocess
  crash, without affecting test results,
- move the igt helper with workload back from subtests to initial
  fixture so workload crash also does not affect test results,
- re-add the second patch which extends the test with an option for
  using an external command as a workload,
- other cleanups suggested by Kasia and Chris.

v4->v5 (second public submission, marked as v2):
- try to restore the device to a working state after each subtest
  (Petri, Daniel).

v3->v4 (first public submission, not marked with any version number):
- run dummy_load from inside subtests (Antonio).

v2->v3 (internal submission):
- run dummy_load from the test process directly (Antonio),
- drop the patch for running external workload (Antonio).

v1->v2 (internal submission):
- run a subprocess with dummy_load instead of external command
  (Antonio),
- keep use of external workload command as an option, move that to a
  separate patch.
-- 
2.20.1