drm/virtio: return virtio_gpu_queue errors

In case queuing virtio commands fails (can happen when
the device got unplugged) pass up the error.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20200908070723.6394-3-kraxel@redhat.com

drivers/gpu/drm/virtio/virtgpu_vq.c

@@ -320,7 +320,7 @@ static struct sg_table *vmalloc_to_sgt(char *data, uint32_t size, int *sg_ents)
 	return sgt;
 }
 
-static void virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev,
+static int virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev,
 				     struct virtio_gpu_vbuffer *vbuf,
 				     struct virtio_gpu_fence *fence,
 				     int elemcnt,
@@ -335,7 +335,7 @@ static void virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev,
 		if (fence && vbuf->objs)
 			virtio_gpu_array_unlock_resv(vbuf->objs);
 		free_vbuf(vgdev, vbuf);
-		return;
+		return -1;
 	}
 
 	if (vgdev->has_indirect)
@@ -373,15 +373,16 @@ static void virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev,
 	spin_unlock(&vgdev->ctrlq.qlock);
 
 	drm_dev_exit(idx);
+	return 0;
 }
 
-static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
+static int virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
 					       struct virtio_gpu_vbuffer *vbuf,
 					       struct virtio_gpu_fence *fence)
 {
 	struct scatterlist *sgs[3], vcmd, vout, vresp;
 	struct sg_table *sgt = NULL;
-	int elemcnt = 0, outcnt = 0, incnt = 0;
+	int elemcnt = 0, outcnt = 0, incnt = 0, ret;
 
 	/* set up vcmd */
 	sg_init_one(&vcmd, vbuf->buf, vbuf->size);
@@ -398,7 +399,7 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
 			if (!sgt) {
 				if (fence && vbuf->objs)
 					virtio_gpu_array_unlock_resv(vbuf->objs);
-				return;
+				return -1;
 			}
 
 			elemcnt += sg_ents;
@@ -419,13 +420,14 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
 		incnt++;
 	}
 
-	virtio_gpu_queue_ctrl_sgs(vgdev, vbuf, fence, elemcnt, sgs, outcnt,
+	ret = virtio_gpu_queue_ctrl_sgs(vgdev, vbuf, fence, elemcnt, sgs, outcnt,
 					incnt);
 
 	if (sgt) {
 		sg_free_table(sgt);
 		kfree(sgt);
 	}
+	return ret;
 }
 
 void virtio_gpu_notify(struct virtio_gpu_device *vgdev)
@@ -444,10 +446,10 @@ void virtio_gpu_notify(struct virtio_gpu_device *vgdev)
 		virtqueue_notify(vgdev->ctrlq.vq);
 }
 
-static void virtio_gpu_queue_ctrl_buffer(struct virtio_gpu_device *vgdev,
+static int virtio_gpu_queue_ctrl_buffer(struct virtio_gpu_device *vgdev,
 					struct virtio_gpu_vbuffer *vbuf)
 {
-	virtio_gpu_queue_fenced_ctrl_buffer(vgdev, vbuf, NULL);
+	return virtio_gpu_queue_fenced_ctrl_buffer(vgdev, vbuf, NULL);
 }
 
 static void virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev,