[PATCH 3/5 v3] drm/virtio: track whether or not a context has been initiated

[Gurchetan Singh]

Use an atomic variable to track whether a context has been
initiated.

v3: Fix possible race via spinlock (@olv)

Signed-off-by: Gurchetan Singh <gurchetansingh at chromium.org>
---
 drivers/gpu/drm/virtio/virtgpu_drv.h   | 2 ++
 drivers/gpu/drm/virtio/virtgpu_ioctl.c | 8 ++++++++
 drivers/gpu/drm/virtio/virtgpu_kms.c   | 2 ++
 3 files changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index 72c1d9b59dfe..99d94a87c28b 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -209,6 +209,8 @@ struct virtio_gpu_device {
 
 struct virtio_gpu_fpriv {
 	uint32_t ctx_id;
+	bool context_initiated;
+	spinlock_t context_lock;
 };
 
 /* virtio_ioctl.c */
diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index de04f80f737d..82312664f2e4 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -44,10 +44,18 @@ void virtio_gpu_create_context(struct drm_device *dev,
 	if (!vgdev->has_virgl_3d)
 		return;
 
+	spin_lock(&vfpriv->context_lock);
+	if (vfpriv->context_initiated)
+		goto out_unlock;
+
 	get_task_comm(dbgname, current);
 	virtio_gpu_cmd_context_create(vgdev, vfpriv->ctx_id,
 				      strlen(dbgname), dbgname);
 	virtio_gpu_notify(vgdev);
+	vfpriv->context_initiated = true;
+
+out_unlock:
+	spin_unlock(&vfpriv->context_lock);
 }
 
 static int virtio_gpu_map_ioctl(struct drm_device *dev, void *data,
diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/virtio/virtgpu_kms.c
index f7e3712502ca..f4a9aa0048d2 100644
--- a/drivers/gpu/drm/virtio/virtgpu_kms.c
+++ b/drivers/gpu/drm/virtio/virtgpu_kms.c
@@ -258,6 +258,8 @@ int virtio_gpu_driver_open(struct drm_device *dev, struct drm_file *file)
 	if (!vfpriv)
 		return -ENOMEM;
 
+	spin_lock_init(&vfpriv->context_lock);
+
 	handle = ida_alloc(&vgdev->ctx_id_ida, GFP_KERNEL);
 	if (handle < 0) {
 		kfree(vfpriv);
-- 
2.25.0.265.gbab2e86ba0-goog