[Intel-gfx] [PATCH 3/4] drm/i915: Skip adding the request to the signal tree is complete

[Chris Wilson]

Enabling the interrupt for the signaler takes a finite amount of time (a
few microseconds) during which it is possible for the request to
complete. Check afterwards and skip adding the request to the signal
rbtree if it complete.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/intel_breadcrumbs.c | 44 ++++++++++++++++++--------------
 1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
index dbcad9f6b2d5..a855771ec1a9 100644
--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
@@ -714,27 +714,33 @@ void intel_engine_enable_signaling(struct drm_i915_gem_request *request,
 	 */
 	wakeup &= __intel_engine_add_wait(engine, &request->signaling.wait);
 
-	/* Now insert ourselves into the retirement ordered list of signals
-	 * on this engine. We track the oldest seqno as that will be the
-	 * first signal to complete.
-	 */
-	parent = NULL;
-	first = true;
-	p = &b->signals.rb_node;
-	while (*p) {
-		parent = *p;
-		if (i915_seqno_passed(seqno,
-				      to_signaler(parent)->signaling.wait.seqno)) {
-			p = &parent->rb_right;
-			first = false;
-		} else {
-			p = &parent->rb_left;
+	if (!__i915_gem_request_completed(request, seqno)) {
+		/* Now insert ourselves into the retirement ordered list of
+		 * signals on this engine. We track the oldest seqno as that
+		 * will be the first signal to complete.
+		 */
+		parent = NULL;
+		first = true;
+		p = &b->signals.rb_node;
+		while (*p) {
+			parent = *p;
+			if (i915_seqno_passed(seqno,
+						to_signaler(parent)->signaling.wait.seqno)) {
+				p = &parent->rb_right;
+				first = false;
+			} else {
+				p = &parent->rb_left;
+			}
 		}
+		rb_link_node(&request->signaling.node, parent, p);
+		rb_insert_color(&request->signaling.node, &b->signals);
+		if (first)
+			rcu_assign_pointer(b->first_signal, request);
+	} else {
+		__intel_engine_remove_wait(engine, &request->signaling.wait);
+		i915_gem_request_put(request);
+		wakeup = false;
 	}
-	rb_link_node(&request->signaling.node, parent, p);
-	rb_insert_color(&request->signaling.node, &b->signals);
-	if (first)
-		rcu_assign_pointer(b->first_signal, request);
 
 	spin_unlock(&b->rb_lock);
 
-- 
2.11.0