1 files changed, 37 insertions, 20 deletions

diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index 108f52e1bf35..78ceb56d7801 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -150,29 +150,49 @@ sched_lock_engine(const struct i915_sched_node *node,
 		  struct intel_engine_cs *locked,
 		  struct sched_cache *cache)
 {
-	struct intel_engine_cs *engine = node_to_request(node)->engine;
+	const struct i915_request *rq = node_to_request(node);
+	struct intel_engine_cs *engine;
 
 	GEM_BUG_ON(!locked);
 
-	if (engine != locked) {
+	/*
+	 * Virtual engines complicate acquiring the engine timeline lock,
+	 * as their rq->engine pointer is not stable until under that
+	 * engine lock. The simple ploy we use is to take the lock then
+	 * check that the rq still belongs to the newly locked engine.
+	 */
+	while (locked != (engine = READ_ONCE(rq->engine))) {
 		spin_unlock(&locked->timeline.lock);
 		memset(cache, 0, sizeof(*cache));
 		spin_lock(&engine->timeline.lock);
+		locked = engine;
 	}
 
-	return engine;
+	GEM_BUG_ON(locked != engine);
+	return locked;
 }
 
-static bool inflight(const struct i915_request *rq,
-		     const struct intel_engine_cs *engine)
+static inline int rq_prio(const struct i915_request *rq)
 {
-	const struct i915_request *active;
+	return rq->sched.attr.priority | __NO_PREEMPTION;
+}
 
-	if (!i915_request_is_active(rq))
-		return false;
+static void kick_submission(struct intel_engine_cs *engine, int prio)
+{
+	const struct i915_request *inflight =
+		port_request(engine->execlists.port);
+
+	/*
+	 * If we are already the currently executing context, don't
+	 * bother evaluating if we should preempt ourselves, or if
+	 * we expect nothing to change as a result of running the
+	 * tasklet, i.e. we have not change the priority queue
+	 * sufficiently to oust the running context.
+	 */
+	if (inflight && !i915_scheduler_need_preempt(prio, rq_prio(inflight)))
+		return;
 
-	active = port_request(engine->execlists.port);
-	return active->hw_context == rq->hw_context;
+	tasklet_hi_schedule(&engine->execlists.tasklet);
 }
 
 static void __i915_schedule(struct i915_sched_node *node,
@@ -189,10 +209,10 @@ static void __i915_schedule(struct i915_sched_node *node,
 	lockdep_assert_held(&schedule_lock);
 	GEM_BUG_ON(prio == I915_PRIORITY_INVALID);
 
-	if (node_signaled(node))
+	if (prio <= READ_ONCE(node->attr.priority))
 		return;
 
-	if (prio <= READ_ONCE(node->attr.priority))
+	if (node_signaled(node))
 		return;
 
 	stack.signaler = node;
@@ -261,6 +281,7 @@ static void __i915_schedule(struct i915_sched_node *node,
 	spin_lock(&engine->timeline.lock);
 
 	/* Fifo and depth-first replacement ensure our deps execute before us */
+	engine = sched_lock_engine(node, engine, &cache);
 	list_for_each_entry_safe_reverse(dep, p, &dfs, dfs_link) {
 		INIT_LIST_HEAD(&dep->dfs_link);
 
@@ -272,8 +293,11 @@ static void __i915_schedule(struct i915_sched_node *node,
 		if (prio <= node->attr.priority || node_signaled(node))
 			continue;
 
+		GEM_BUG_ON(node_to_request(node)->engine != engine);
+
 		node->attr.priority = prio;
 		if (!list_empty(&node->link)) {
+			GEM_BUG_ON(intel_engine_is_virtual(engine));
 			if (!cache.priolist)
 				cache.priolist =
 					i915_sched_lookup_priolist(engine,
@@ -297,15 +321,8 @@ static void __i915_schedule(struct i915_sched_node *node,
 
 		engine->execlists.queue_priority_hint = prio;
 
-		/*
-		 * If we are already the currently executing context, don't
-		 * bother evaluating if we should preempt ourselves.
-		 */
-		if (inflight(node_to_request(node), engine))
-			continue;
-
 		/* Defer (tasklet) submission until after all of our updates. */
-		tasklet_hi_schedule(&engine->execlists.tasklet);
+		kick_submission(engine, prio);
 	}
 
 	spin_unlock(&engine->timeline.lock);