This series is the result of debugging issues root caused to races between the GuC's destroyed_worker_func being triggered vs repeating suspend-resume cycles with concurrent delayed fence signals for engine-freeing. The reproduction steps require that an app is created right before the start of the suspend cycle where it creates a new gem context and submits a tiny workload that would complete in the middle of the suspend cycle. However this app uses dma-buffer sharing or dma-fence with non-GPU objects or signals that eventually triggers a FENCE_FREE via__i915_sw_fence_notify that connects to engines_notify -> free_engines_rcu -> intel_context_put -> kref_put(&ce->ref..) that queues the worker after the GuCs CTB has been disabled (i.e. after i915-gem's suspend-late flows). This sequence is a corner-case and required repeating this app->suspend->resume cycle ~1500 times across 4 identical systems to see it once. That said, based on above callstack, it is clear that merely flushing the context destruction worker, which is obviously missing and needed, isn't sufficient. Because of that, this series adds additional patches besides the obvious flushing of the worker during the suspend flows. It includes (1) closing a race between sending the context- deregistration H2G vs the CTB getting disabled in the midst of it (by detecing the failure and unrolling the guc-lrc-unpin flow) and (2) not infinitely waiting in intel_gt_pm_wait_timeout_for_idle when in the suspend-flow. Alan Previn (3): drm/i915/guc: Flush context destruction worker at suspend drm/i915/guc: Close deregister-context race against CT-loss drm/i915/gt: Timeout when waiting for idle in suspending drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 +- drivers/gpu/drm/i915/gt/intel_gt_pm.c | 13 +++++- drivers/gpu/drm/i915/gt/intel_gt_pm.h | 7 ++- .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 43 +++++++++++++++++-- .../gpu/drm/i915/gt/uc/intel_guc_submission.h | 2 + drivers/gpu/drm/i915/gt/uc/intel_uc.c | 7 +++ drivers/gpu/drm/i915/gt/uc/intel_uc.h | 1 + drivers/gpu/drm/i915/intel_wakeref.c | 14 ++++-- drivers/gpu/drm/i915/intel_wakeref.h | 5 ++- 9 files changed, 80 insertions(+), 14 deletions(-) base-commit: 20610a111d61d6945d578360942dc5c7bd828eb5 -- 2.39.0
