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

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_active_types.h b/drivers/gpu/drm/i915/i915_active_types.h
index ae3ee441c114..1854e7d168c1 100644
--- a/drivers/gpu/drm/i915/i915_active_types.h
+++ b/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;