On Fri, Feb 14, 2020 at 11:27 AM Chia-I Wu olvaffe@gmail.com wrote:
On Thu, Feb 13, 2020 at 3:18 PM Gurchetan Singh gurchetansingh@chromium.org wrote:
Use an atomic variable to track whether a context has been initiated.
v2: Fix possible race (@olv)
Signed-off-by: Gurchetan Singh gurchetansingh@chromium.org
drivers/gpu/drm/virtio/virtgpu_drv.h | 1 + drivers/gpu/drm/virtio/virtgpu_ioctl.c | 3 +++ drivers/gpu/drm/virtio/virtgpu_kms.c | 1 + 3 files changed, 5 insertions(+)
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h index 72c1d9b59dfe..ca505984f8ab 100644 --- a/drivers/gpu/drm/virtio/virtgpu_drv.h +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h @@ -209,6 +209,7 @@ struct virtio_gpu_device {
struct virtio_gpu_fpriv { uint32_t ctx_id;
atomic_t context_initiated;};
/* virtio_ioctl.c */ diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c index 896c3f419a6d..a98884462944 100644 --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c @@ -44,6 +44,9 @@ void virtio_gpu_create_context(struct drm_device *dev, if (!vgdev->has_virgl_3d) return;
if (!atomic_add_unless(&vfpriv->context_initiated, 1, 1))return;How does this work? When thread A and B enter this function at the same time, and thread B returns early, it is possible that thread B queues other commands before thread A has the chance to queue virtio_gpu_cmd_context_create.
Good catch, I'll add a spinlock in v3.
get_task_comm(dbgname, current); virtio_gpu_cmd_context_create(vgdev, vfpriv->ctx_id, strlen(dbgname), dbgname);diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/virtio/virtgpu_kms.c index 282558576527..25248bad3fc4 100644 --- a/drivers/gpu/drm/virtio/virtgpu_kms.c +++ b/drivers/gpu/drm/virtio/virtgpu_kms.c @@ -263,6 +263,7 @@ int virtio_gpu_driver_open(struct drm_device *dev, struct drm_file *file) }
vfpriv->ctx_id = handle + 1;
atomic_set(&vfpriv->context_initiated, 0); file->driver_priv = vfpriv; virtio_gpu_create_context(dev, file); return 0;-- 2.25.0.265.gbab2e86ba0-goog