drm/i915: Markup expected timeline locks for i915_active

As every i915_active_request should be serialised by a dedicated lock,
i915_active consists of a tree of locks; one for each node. Markup up
the i915_active_request with what lock is supposed to be guarding it so
that we can verify that the serialised updated are indeed serialised.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816121000.8507-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/display/intel_overlay.c

@@ -230,7 +230,7 @@ alloc_request(struct intel_overlay *overlay, void (*fn)(struct intel_overlay *))
 	if (IS_ERR(rq))
 		return rq;
 
-	err = i915_active_ref(&overlay->last_flip, rq->fence.context, rq);
+	err = i915_active_ref(&overlay->last_flip, rq->timeline, rq);
 	if (err) {
 		i915_request_add(rq);
 		return ERR_PTR(err);

drivers/gpu/drm/i915/gem/i915_gem_client_blt.c

@@ -211,7 +211,7 @@ static void clear_pages_worker(struct work_struct *work)
 	 * keep track of the GPU activity within this vma/request, and
 	 * propagate the signal from the request to w->dma.
 	 */
-	err = i915_active_ref(&vma->active, rq->fence.context, rq);
+	err = i915_active_ref(&vma->active, rq->timeline, rq);
 	if (err)
 		goto out_request;
 

drivers/gpu/drm/i915/gem/i915_gem_context.c

@@ -908,7 +908,7 @@ static int context_barrier_task(struct i915_gem_context *ctx,
 		if (emit)
 			err = emit(rq, data);
 		if (err == 0)
-			err = i915_active_ref(&cb->base, rq->fence.context, rq);
+			err = i915_active_ref(&cb->base, rq->timeline, rq);
 
 		i915_request_add(rq);
 		if (err)

drivers/gpu/drm/i915/gt/intel_context.c

@@ -306,10 +306,10 @@ int intel_context_prepare_remote_request(struct intel_context *ce,
 
 		/* Queue this switch after current activity by this context. */
 		err = i915_active_request_set(&tl->last_request, rq);
+		mutex_unlock(&tl->mutex);
 		if (err)
-			goto unlock;
+			return err;
 	}
-	lockdep_assert_held(&tl->mutex);
 
 	/*
 	 * Guarantee context image and the timeline remains pinned until the
@@ -319,12 +319,7 @@ int intel_context_prepare_remote_request(struct intel_context *ce,
 	 * words transfer the pinned ce object to tracked active request.
 	 */
 	GEM_BUG_ON(i915_active_is_idle(&ce->active));
-	err = i915_active_ref(&ce->active, rq->fence.context, rq);
-
-unlock:
-	if (rq->timeline != tl)
-		mutex_unlock(&tl->mutex);
-	return err;
+	return i915_active_ref(&ce->active, rq->timeline, rq);
 }
 
 struct i915_request *intel_context_create_request(struct intel_context *ce)

drivers/gpu/drm/i915/gt/intel_engine_pool.h

@@ -18,7 +18,7 @@ static inline int
 intel_engine_pool_mark_active(struct intel_engine_pool_node *node,
 			      struct i915_request *rq)
 {
-	return i915_active_ref(&node->active, rq->fence.context, rq);
+	return i915_active_ref(&node->active, rq->timeline, rq);
 }
 
 static inline void

drivers/gpu/drm/i915/gt/intel_timeline.c

@@ -254,7 +254,7 @@ int intel_timeline_init(struct intel_timeline *timeline,
 
 	mutex_init(&timeline->mutex);
 
-	INIT_ACTIVE_REQUEST(&timeline->last_request);
+	INIT_ACTIVE_REQUEST(&timeline->last_request, &timeline->mutex);
 	INIT_LIST_HEAD(&timeline->requests);
 
 	i915_syncmap_init(&timeline->sync);
@@ -440,8 +440,7 @@ __intel_timeline_get_seqno(struct intel_timeline *tl,
 	 * free it after the current request is retired, which ensures that
 	 * all writes into the cacheline from previous requests are complete.
 	 */
-	err = i915_active_ref(&tl->hwsp_cacheline->active,
-			      tl->fence_context, rq);
+	err = i915_active_ref(&tl->hwsp_cacheline->active, tl, rq);
 	if (err)
 		goto err_cacheline;
 
@@ -492,7 +491,7 @@ int intel_timeline_get_seqno(struct intel_timeline *tl,
 static int cacheline_ref(struct intel_timeline_cacheline *cl,
 			 struct i915_request *rq)
 {
-	return i915_active_ref(&cl->active, rq->fence.context, rq);
+	return i915_active_ref(&cl->active, rq->timeline, rq);
 }
 
 int intel_timeline_read_hwsp(struct i915_request *from,

drivers/gpu/drm/i915/gt/selftest_timeline.c

@@ -689,7 +689,9 @@ static int live_hwsp_wrap(void *arg)
 
 		tl->seqno = -4u;
 
+		mutex_lock_nested(&tl->mutex, SINGLE_DEPTH_NESTING);
 		err = intel_timeline_get_seqno(tl, rq, &seqno[0]);
+		mutex_unlock(&tl->mutex);
 		if (err) {
 			i915_request_add(rq);
 			goto out;
@@ -704,7 +706,9 @@ static int live_hwsp_wrap(void *arg)
 		}
 		hwsp_seqno[0] = tl->hwsp_seqno;
 
+		mutex_lock_nested(&tl->mutex, SINGLE_DEPTH_NESTING);
 		err = intel_timeline_get_seqno(tl, rq, &seqno[1]);
+		mutex_unlock(&tl->mutex);
 		if (err) {
 			i915_request_add(rq);
 			goto out;

drivers/gpu/drm/i915/gt/selftests/mock_timeline.c

@@ -15,7 +15,7 @@ void mock_timeline_init(struct intel_timeline *timeline, u64 context)
 
 	mutex_init(&timeline->mutex);
 
-	INIT_ACTIVE_REQUEST(&timeline->last_request);
+	INIT_ACTIVE_REQUEST(&timeline->last_request, &timeline->mutex);
 	INIT_LIST_HEAD(&timeline->requests);
 
 	i915_syncmap_init(&timeline->sync);

drivers/gpu/drm/i915/i915_active.c

@@ -169,10 +169,11 @@ node_retire(struct i915_active_request *base, struct i915_request *rq)
 }
 
 static struct i915_active_request *
-active_instance(struct i915_active *ref, u64 idx)
+active_instance(struct i915_active *ref, struct intel_timeline *tl)
 {
 	struct active_node *node, *prealloc;
 	struct rb_node **p, *parent;
+	u64 idx = tl->fence_context;
 
 	/*
 	 * We track the most recently used timeline to skip a rbtree search
@@ -211,7 +212,7 @@ active_instance(struct i915_active *ref, u64 idx)
 	}
 
 	node = prealloc;
-	i915_active_request_init(&node->base, NULL, node_retire);
+	i915_active_request_init(&node->base, &tl->mutex, NULL, node_retire);
 	node->ref = ref;
 	node->timeline = idx;
 
@@ -294,18 +295,20 @@ __active_del_barrier(struct i915_active *ref, struct active_node *node)
 }
 
 int i915_active_ref(struct i915_active *ref,
-		    u64 timeline,
+		    struct intel_timeline *tl,
 		    struct i915_request *rq)
 {
 	struct i915_active_request *active;
 	int err;
 
+	lockdep_assert_held(&tl->mutex);
+
 	/* Prevent reaping in case we malloc/wait while building the tree */
 	err = i915_active_acquire(ref);
 	if (err)
 		return err;
 
-	active = active_instance(ref, timeline);
+	active = active_instance(ref, tl);
 	if (!active) {
 		err = -ENOMEM;
 		goto out;
@@ -596,6 +599,10 @@ int i915_active_acquire_preallocate_barrier(struct i915_active *ref,
 				goto unwind;
 			}
 
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
+			node->base.lock =
+				&engine->kernel_context->timeline->mutex;
+#endif
 			RCU_INIT_POINTER(node->base.request, NULL);
 			node->base.retire = node_retire;
 			node->timeline = idx;
@@ -701,6 +708,10 @@ int i915_active_request_set(struct i915_active_request *active,
 {
 	int err;
 
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
+	lockdep_assert_held(active->lock);
+#endif
+
 	/* Must maintain ordering wrt previous active requests */
 	err = i915_request_await_active_request(rq, active);
 	if (err)

drivers/gpu/drm/i915/i915_active.h

@@ -58,15 +58,20 @@ void i915_active_retire_noop(struct i915_active_request *active,
  */
 static inline void
 i915_active_request_init(struct i915_active_request *active,
+			 struct mutex *lock,
 			 struct i915_request *rq,
 			 i915_active_retire_fn retire)
 {
 	RCU_INIT_POINTER(active->request, rq);
 	INIT_LIST_HEAD(&active->link);
 	active->retire = retire ?: i915_active_retire_noop;
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
+	active->lock = lock;
+#endif
 }
 
-#define INIT_ACTIVE_REQUEST(name) i915_active_request_init((name), NULL, NULL)
+#define INIT_ACTIVE_REQUEST(name, lock) \
+	i915_active_request_init((name), (lock), NULL, NULL)
 
 /**
  * i915_active_request_set - updates the tracker to watch the current request
@@ -81,6 +86,9 @@ static inline void
 __i915_active_request_set(struct i915_active_request *active,
 			  struct i915_request *request)
 {
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
+	lockdep_assert_held(active->lock);
+#endif
 	list_move(&active->link, &request->active_list);
 	rcu_assign_pointer(active->request, request);
 }
@@ -362,7 +370,7 @@ void __i915_active_init(struct drm_i915_private *i915,
 } while (0)
 
 int i915_active_ref(struct i915_active *ref,
-		    u64 timeline,
+		    struct intel_timeline *tl,
 		    struct i915_request *rq);
 
 int i915_active_wait(struct i915_active *ref);

drivers/gpu/drm/i915/i915_active_types.h

@@ -24,6 +24,21 @@ struct i915_active_request {
 	struct i915_request __rcu *request;
 	struct list_head link;
 	i915_active_retire_fn retire;
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
+	/*
+	 * Incorporeal!
+	 *
+	 * Updates to the i915_active_request must be serialised under a lock
+	 * to ensure that the timeline is ordered. Normally, this is the
+	 * timeline->mutex, but another mutex may be used so long as it is
+	 * done so consistently.
+	 *
+	 * For lockdep tracking of the above, we store the lock we intend
+	 * to always use for updates of this i915_active_request during
+	 * construction and assert that is held on every update.
+	 */
+	struct mutex *lock;
+#endif
 };
 
 struct active_node;

drivers/gpu/drm/i915/i915_vma.c

@@ -903,14 +903,14 @@ int i915_vma_move_to_active(struct i915_vma *vma,
 	 * add the active reference first and queue for it to be dropped
 	 * *last*.
 	 */
-	err = i915_active_ref(&vma->active, rq->fence.context, rq);
+	err = i915_active_ref(&vma->active, rq->timeline, rq);
 	if (unlikely(err))
 		return err;
 
 	if (flags & EXEC_OBJECT_WRITE) {
 		if (intel_frontbuffer_invalidate(obj->frontbuffer, ORIGIN_CS))
 			i915_active_ref(&obj->frontbuffer->write,
-					rq->fence.context,
+					rq->timeline,
 					rq);
 
 		reservation_object_add_excl_fence(vma->resv, &rq->fence);

drivers/gpu/drm/i915/selftests/i915_active.c

@@ -110,8 +110,7 @@ __live_active_setup(struct drm_i915_private *i915)
 						       submit,
 						       GFP_KERNEL);
 		if (err >= 0)
-			err = i915_active_ref(&active->base,
-					      rq->fence.context, rq);
+			err = i915_active_ref(&active->base, rq->timeline, rq);
 		i915_request_add(rq);
 		if (err) {
 			pr_err("Failed to track active ref!\n");