[PATCH v4 0/2] Add gem_change_handle_race test suite for DRM_IOCTL_GEM_CHANGE_HANDLE

From: Vitaly Prosyak <[email protected]>

This series adds comprehensive race condition testing for the proposed
DRM_IOCTL_GEM_CHANGE_HANDLE ioctl to validate concurrent operation handling
in GEM handle management.

The test suite is GPU-agnostic and works with both Intel i915 and AMD amdgpu
drivers, focusing on proper locking and handle lifecycle management during
concurrent GEM operations.

v4 changes (addressing Kamil Konieczny's review feedback):
 - Removed running_under_gdb() function from patch 1 entirely
   (was wastefully added in patch 1 and removed in patch 2 in v3)
 - Fixed all double newlines throughout both patches
 - Moved all formatting/style fixes to patch 1 (patch 2 is now clean):
   * Removed #define _GNU_SOURCE (already defined by meson build system)
   * Added header comment explaining tests/intel/ location
   * Fixed check_kernel_traces() brace style
   * Enhanced pin_to_cpu() with error handling and ARM compatibility
   * Fixed variable declarations (C89 style)
   * Removed unnecessary braces in if statements
   * Fixed static variable initialization
 - Patch 2 is now completely clean: only adds new test functions
   (234 insertions, 0 deletions - no modifications to patch 1 code)
 - Added git format-patch -v4 for version tracking
 - Added meson.build entry to patch 1
 - Fixed compilation warning: _GNU_SOURCE redefined (removed from source)

v3 changes (addressing Kamil Konieczny's review feedback):
 - Removed reference to external documentation (RACE_CONDITIONS_EXPLAINED.md)
 - Sanitized test descriptions and comments (security consideration)
 - Renamed 'race-darknavy-cve' to 'race-close-before-lock'
 - Renamed internal functions and variables for clarity
 - No functional changes to test logic

v2 changes (addressing Kamil Konieczny's review feedback):
 - Added header comment explaining why test is in tests/intel/ directory
 - ARM compatibility fixes (graceful CPU pinning failure handling)
 - Made pin_to_cpu() handle failures gracefully with igt_debug()

v1:
 - Initial submission with 7 race condition subtests

Test coverage:
==============

Patch 1 adds 7 race condition subtests:
- race-change-vs-close: CHANGE_HANDLE races against GEM_CLOSE
- race-change-vs-change: Two CHANGE_HANDLE ops race on same handle
- race-change-vs-prime: CHANGE_HANDLE races against PRIME_HANDLE_TO_FD
- race-aggressive-change-vs-close: High-iteration close vs change
- race-exploit-single-thread: Sequential swap+close pattern
- race-exploit-random-handles: Random handle stress test
- race-close-before-lock: Close-before-lock scenario with CPU pinning

Patch 2 adds 5 edge-case and functional subtests:
- noop-same-handle: handle == new_handle returns success (noop)
- invalid-new-handle-exceeds-int-max: new_handle > INT_MAX returns -EINVAL
- invalid-handle-nonexistent: non-existent handle returns -ENOENT
- edge-new-handle-zero: new_handle == 0 (documents current behavior)
- functional-rename-verification: Verifies actual rename operation works

Testing:
========
Tested on AMD Navi 32 (GFX11) with amdgpu driver:
- All 12 subtests compile cleanly
- All subtests execute successfully
- No compilation warnings

The test is located in tests/intel/ following IGT convention for gem_* tests,
and uses i915/gem.h infrastructure while remaining vendor-agnostic via DRM core.

Cc: Simona Vetter <[email protected]>
Cc: Kamil Konieczny <[email protected]>
Cc: Christian König <[email protected]>
Cc: Alex Deucher <[email protected]>
Cc: Jesse Zhang <[email protected]>

Vitaly Prosyak (2):
  tests/intel: Add gem_change_handle_race test suite
  tests/intel/gem_change_handle_race: Add edge-case and functional
    subtests

 tests/intel/gem_change_handle_race.c | 1977 ++++++++++++++++++++++++++
 tests/meson.build                    |    1 +
 2 files changed, 1978 insertions(+)
 create mode 100644 tests/intel/gem_change_handle_race.c

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2.43.0