From b647c7df01b75761b4c0b1cb6f4841088c0b1121 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 23 Sep 2019 16:28:42 +0100 Subject: [PATCH] drm/i915: Fixup preempt-to-busy vs resubmission of a virtual request As preempt-to-busy leaves the request on the HW as the resubmission is processed, that request may complete in the background and even cause a second virtual request to enter queue. This second virtual request breaks our "single request in the virtual pipeline" assumptions. Furthermore, as the virtual request may be completed and retired, we lose the reference the virtual engine assumes is held. Normally, just removing the request from the scheduler queue removes it from the engine, but the virtual engine keeps track of its singleton request via its ve->request. This pointer needs protecting with a reference. v2: Drop unnecessary motion of rq->engine = owner Fixes: 22b7a426bbe1 ("drm/i915/execlists: Preempt-to-busy") Signed-off-by: Chris Wilson Cc: Mika Kuoppala Cc: Tvrtko Ursulin Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20190923152844.8914-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/gt/intel_lrc.c | 32 ++++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index bff4c6a..114819f 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -1256,6 +1256,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine) submit = true; last = rq; } + i915_request_put(rq); /* * Hmm, we have a bunch of virtual engine requests, @@ -2556,6 +2557,7 @@ static void execlists_cancel_requests(struct intel_engine_cs *engine) rq->engine = engine; __i915_request_submit(rq); + i915_request_put(rq); ve->base.execlists.queue_priority_hint = INT_MIN; } @@ -3809,6 +3811,8 @@ submit_engine: static void virtual_submit_request(struct i915_request *rq) { struct virtual_engine *ve = to_virtual_engine(rq->engine); + struct i915_request *old; + unsigned long flags; GEM_TRACE("%s: rq=%llx:%lld\n", ve->base.name, @@ -3817,15 +3821,31 @@ static void virtual_submit_request(struct i915_request *rq) GEM_BUG_ON(ve->base.submit_request != virtual_submit_request); - GEM_BUG_ON(ve->request); - GEM_BUG_ON(!list_empty(virtual_queue(ve))); + spin_lock_irqsave(&ve->base.active.lock, flags); + + old = ve->request; + if (old) { /* background completion event from preempt-to-busy */ + GEM_BUG_ON(!i915_request_completed(old)); + __i915_request_submit(old); + i915_request_put(old); + } - ve->base.execlists.queue_priority_hint = rq_prio(rq); - WRITE_ONCE(ve->request, rq); + if (i915_request_completed(rq)) { + __i915_request_submit(rq); - list_move_tail(&rq->sched.link, virtual_queue(ve)); + ve->base.execlists.queue_priority_hint = INT_MIN; + ve->request = NULL; + } else { + ve->base.execlists.queue_priority_hint = rq_prio(rq); + ve->request = i915_request_get(rq); + + GEM_BUG_ON(!list_empty(virtual_queue(ve))); + list_move_tail(&rq->sched.link, virtual_queue(ve)); + + tasklet_schedule(&ve->base.execlists.tasklet); + } - tasklet_schedule(&ve->base.execlists.tasklet); + spin_unlock_irqrestore(&ve->base.active.lock, flags); } static struct ve_bond * -- 2.7.4