From 735e0eb669a6bb4f6f7b9574d55b451c838747bd Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu, 8 Jun 2017 12:14:04 +0100
Subject: [PATCH] drm/i915: Skip adding the request to the signal tree is complete
Git-commit: 735e0eb669a6bb4f6f7b9574d55b451c838747bd
Patch-mainline: v4.13-rc1
References: FATE#322643 bsc#1055900

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@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170608111405.16466-3-chris@chris-wilson.co.uk
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/i915/intel_breadcrumbs.c |   49 +++++++++++++++++--------------
 1 file changed, 28 insertions(+), 21 deletions(-)

--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
@@ -678,8 +678,6 @@ void intel_engine_enable_signaling(struc
 {
 	struct intel_engine_cs *engine = request->engine;
 	struct intel_breadcrumbs *b = &engine->breadcrumbs;
-	struct rb_node *parent, **p;
-	bool first;
 	u32 seqno;
 
 	/* Note that we may be called from an interrupt handler on another
@@ -714,27 +712,36 @@ void intel_engine_enable_signaling(struc
 	 */
 	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)) {
+		struct rb_node *parent, **p;
+		bool first;
+
+		/* 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);