From e543e370ec3160c06c2cd897477150dfb23f1afd Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 6 Feb 2020 20:49:12 +0000 Subject: [PATCH] drm/i915/gt: Prevent queuing retire workers on the virtual engine Virtual engines are fleeting. They carry a reference count and may be freed when their last request is retired. This makes them unsuitable for the task of housing engine->retire.work so assert that it is not used. Tvrtko tracked down an instance where we did indeed violate this rule. In virtual_submit_request, we flush a completed request directly with __i915_request_submit and this causes us to queue that request on the veng's breadcrumb list and signal it. Leading us down a path where we should not attach the retire. Reported-by: Tvrtko Ursulin Fixes: dc93c9b69315 ("drm/i915/gt: Schedule request retirement when signaler idles") Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Reviewed-by: Mika Kuoppala Link: https://patchwork.freedesktop.org/patch/msgid/20200206204915.2636606-1-chris@chris-wilson.co.uk (cherry picked from commit f91d8156ab8afb32447cd2bf3189219bab943f18) Signed-off-by: Jani Nikula --- drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 3 +++ drivers/gpu/drm/i915/gt/intel_gt_requests.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c index 0ba524a414c6..cbad7fe722ce 100644 --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c @@ -136,6 +136,9 @@ static void add_retire(struct intel_breadcrumbs *b, struct intel_timeline *tl) struct intel_engine_cs *engine = container_of(b, struct intel_engine_cs, breadcrumbs); + if (unlikely(intel_engine_is_virtual(engine))) + engine = intel_virtual_engine_get_sibling(engine, 0); + intel_engine_add_retire(engine, tl); } diff --git a/drivers/gpu/drm/i915/gt/intel_gt_requests.c b/drivers/gpu/drm/i915/gt/intel_gt_requests.c index 7ef1d37970f6..8a5054f21bf8 100644 --- a/drivers/gpu/drm/i915/gt/intel_gt_requests.c +++ b/drivers/gpu/drm/i915/gt/intel_gt_requests.c @@ -99,6 +99,9 @@ static bool add_retire(struct intel_engine_cs *engine, void intel_engine_add_retire(struct intel_engine_cs *engine, struct intel_timeline *tl) { + /* We don't deal well with the engine disappearing beneath us */ + GEM_BUG_ON(intel_engine_is_virtual(engine)); + if (add_retire(engine, tl)) schedule_work(&engine->retire_work); } -- 2.11.0