drm/i915: Drop the deferred active reference

An old optimisation to reduce the number of atomics per batch sadly
relies on struct_mutex for coordination. In order to remove struct_mutex
from serialising object/context closing, always taking and releasing an
active reference on first use / last use greatly simplifies the locking.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190528092956.14910-15-chris@chris-wilson.co.uk

4 files changed, 3 insertions, 14 deletions

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index 672dde71a46c..6b838948ba24 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -527,7 +527,7 @@ static void cleanup_status_page(struct intel_engine_cs *engine)
 		i915_vma_unpin(vma);
 
 	i915_gem_object_unpin_map(vma->obj);
-	__i915_gem_object_release_unless_active(vma->obj);
+	i915_gem_object_put(vma->obj);
 }
 
 static int pin_ggtt_status_page(struct intel_engine_cs *engine,
diff --git a/drivers/gpu/drm/i915/gt/intel_ringbuffer.c b/drivers/gpu/drm/i915/gt/intel_ringbuffer.c
index 66d5a52d505c..ff58d658e3e2 100644
--- a/drivers/gpu/drm/i915/gt/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/gt/intel_ringbuffer.c
@@ -1302,10 +1302,9 @@ intel_engine_create_ring(struct intel_engine_cs *engine,
 void intel_ring_free(struct kref *ref)
 {
 	struct intel_ring *ring = container_of(ref, typeof(*ring), ref);
-	struct drm_i915_gem_object *obj = ring->vma->obj;
 
 	i915_vma_close(ring->vma);
-	__i915_gem_object_release_unless_active(obj);
+	i915_vma_put(ring->vma);
 
 	i915_timeline_put(ring->timeline);
 	kfree(ring);
diff --git a/drivers/gpu/drm/i915/gt/selftest_hangcheck.c b/drivers/gpu/drm/i915/gt/selftest_hangcheck.c
index c3fa10fd9383..3be67e561c26 100644
--- a/drivers/gpu/drm/i915/gt/selftest_hangcheck.c
+++ b/drivers/gpu/drm/i915/gt/selftest_hangcheck.c
@@ -120,15 +120,8 @@ static int move_to_active(struct i915_vma *vma,
 	i915_vma_lock(vma);
 	err = i915_vma_move_to_active(vma, rq, flags);
 	i915_vma_unlock(vma);
-	if (err)
-		return err;
-
-	if (!i915_gem_object_has_active_reference(vma->obj)) {
-		i915_gem_object_get(vma->obj);
-		i915_gem_object_set_active_reference(vma->obj);
-	}
 
-	return 0;
+	return err;
 }
 
 static struct i915_request *
diff --git a/drivers/gpu/drm/i915/gt/selftest_workarounds.c b/drivers/gpu/drm/i915/gt/selftest_workarounds.c
index 38a69acf60ae..2cb1519fde42 100644
--- a/drivers/gpu/drm/i915/gt/selftest_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/selftest_workarounds.c
@@ -142,9 +142,6 @@ read_nonprivs(struct i915_gem_context *ctx, struct intel_engine_cs *engine)
 	}
 	intel_ring_advance(rq, cs);
 
-	i915_gem_object_get(result);
-	i915_gem_object_set_active_reference(result);
-
 	i915_request_add(rq);
 	i915_vma_unpin(vma);