drm/i915/execlists: Offline error capture
Currently, we skip error capture upon forced preemption. We apply forced preemption when there is a higher priority request that should be running but is being blocked, and we skip inline error capture so that the preemption request is not further delayed by a user controlled capture -- extending the denial of service. However, preemption reset is also used for heartbeats and regular GPU hangs. By skipping the error capture, we remove the ability to debug GPU hangs. In order to capture the error without delaying the preemption request further, we can do an out-of-line capture by removing the guilty request from the execution queue and scheduling a worker to dump that request. When removing a request, we need to remove the entire context and all descendants from the execution queue, so that they do not jump past. Closes: https://gitlab.freedesktop.org/drm/intel/issues/738 Fixes: 3a7a92ab ("drm/i915/execlists: Force preemption") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200116184754.2860848-3-chris@chris-wilson.co.uk
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