drm/i915: extract some common olr+wedge code

The new wait_rendering ioctl also needs to check for an oustanding
lazy request, and we already duplicate that logic at three places. So
extract it.

While at it, also extract the code to check the gpu wedging state to
improve code flow.

v2: Don't use seqno as an outparam (Chris)

v3 by danvet: Kill stale comment and pimp commit message
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem.c

@@ -1819,6 +1819,57 @@ i915_gem_retire_work_handler(struct work_struct *work)
 	mutex_unlock(&dev->struct_mutex);
 }
 
+static int
+i915_gem_check_wedge(struct drm_i915_private *dev_priv)
+{
+	BUG_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
+
+	if (atomic_read(&dev_priv->mm.wedged)) {
+		struct completion *x = &dev_priv->error_completion;
+		bool recovery_complete;
+		unsigned long flags;
+
+		/* Give the error handler a chance to run. */
+		spin_lock_irqsave(&x->wait.lock, flags);
+		recovery_complete = x->done > 0;
+		spin_unlock_irqrestore(&x->wait.lock, flags);
+
+		return recovery_complete ? -EIO : -EAGAIN;
+	}
+
+	return 0;
+}
+
+/*
+ * Compare seqno against outstanding lazy request. Emit a request if they are
+ * equal.
+ */
+static int
+i915_gem_check_olr(struct intel_ring_buffer *ring, u32 seqno)
+{
+	int ret = 0;
+
+	BUG_ON(!mutex_is_locked(&ring->dev->struct_mutex));
+
+	if (seqno == ring->outstanding_lazy_request) {
+		struct drm_i915_gem_request *request;
+
+		request = kzalloc(sizeof(*request), GFP_KERNEL);
+		if (request == NULL)
+			return -ENOMEM;
+
+		ret = i915_add_request(ring, NULL, request);
+		if (ret) {
+			kfree(request);
+			return ret;
+		}
+
+		BUG_ON(seqno != request->seqno);
+	}
+
+	return ret;
+}
+
 static int __wait_seqno(struct intel_ring_buffer *ring, u32 seqno,
 			bool interruptible)
 {
@@ -1862,34 +1913,13 @@ i915_wait_request(struct intel_ring_buffer *ring,
 
 	BUG_ON(seqno == 0);
 
-	if (atomic_read(&dev_priv->mm.wedged)) {
-		struct completion *x = &dev_priv->error_completion;
-		bool recovery_complete;
-		unsigned long flags;
-
-		/* Give the error handler a chance to run. */
-		spin_lock_irqsave(&x->wait.lock, flags);
-		recovery_complete = x->done > 0;
-		spin_unlock_irqrestore(&x->wait.lock, flags);
-
-		return recovery_complete ? -EIO : -EAGAIN;
-	}
-
-	if (seqno == ring->outstanding_lazy_request) {
-		struct drm_i915_gem_request *request;
-
-		request = kzalloc(sizeof(*request), GFP_KERNEL);
-		if (request == NULL)
-			return -ENOMEM;
-
-		ret = i915_add_request(ring, NULL, request);
-		if (ret) {
-			kfree(request);
+	ret = i915_gem_check_wedge(dev_priv);
+	if (ret)
 		return ret;
-		}
 
-		seqno = request->seqno;
-	}
+	ret = i915_gem_check_olr(ring, seqno);
+	if (ret)
+		return ret;
 
 	ret = __wait_seqno(ring, seqno, dev_priv->mm.interruptible);
 	if (atomic_read(&dev_priv->mm.wedged))
@@ -1957,22 +1987,9 @@ i915_gem_object_sync(struct drm_i915_gem_object *obj,
 	if (seqno <= from->sync_seqno[idx])
 		return 0;
 
-	if (seqno == from->outstanding_lazy_request) {
-		struct drm_i915_gem_request *request;
-
-		request = kzalloc(sizeof(*request), GFP_KERNEL);
-		if (request == NULL)
-			return -ENOMEM;
-
-		ret = i915_add_request(from, NULL, request);
-		if (ret) {
-			kfree(request);
+	ret = i915_gem_check_olr(obj->ring, seqno);
+	if (ret)
 		return ret;
-		}
-
-		seqno = request->seqno;
-	}
-
 
 	ret = to->sync_to(to, from, seqno);
 	if (!ret)
@@ -3160,20 +3177,9 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
 		if (obj->base.write_domain & I915_GEM_GPU_DOMAINS) {
 			ret = i915_gem_flush_ring(obj->ring,
 						  0, obj->base.write_domain);
-		} else if (obj->ring->outstanding_lazy_request ==
-			   obj->last_rendering_seqno) {
-			struct drm_i915_gem_request *request;
-
-			/* This ring is not being cleared by active usage,
-			 * so emit a request to do so.
-			 */
-			request = kzalloc(sizeof(*request), GFP_KERNEL);
-			if (request) {
-				ret = i915_add_request(obj->ring, NULL, request);
-				if (ret)
-					kfree(request);
-			} else
-				ret = -ENOMEM;
+		} else {
+			ret = i915_gem_check_olr(obj->ring,
+						 obj->last_rendering_seqno);
 		}
 
 		/* Update the active list for the hardware's current position.