2019-06-17 11:15:30

by Gerd Hoffmann

Subject: [PATCH 2/4] drm/virtio: switch virtio_gpu_wait_ioctl() to gem helper.

Use drm_gem_reservation_object_wait() in virtio_gpu_wait_ioctl().

Signed-off-by: Gerd Hoffmann <[email protected]>
---
drivers/gpu/drm/virtio/virtgpu_ioctl.c | 18 ++++--------------
1 file changed, 4 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index c0ba1ead740f..e38a6bb46cc7 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -464,23 +464,13 @@ static int virtio_gpu_wait_ioctl(struct drm_device *dev, void *data,
struct drm_file *file)
{
struct drm_virtgpu_3d_wait *args = data;
- struct drm_gem_object *gobj = NULL;
- struct virtio_gpu_object *qobj = NULL;
- int ret;
- bool nowait = false;
-
- gobj = drm_gem_object_lookup(file, args->handle);
- if (gobj == NULL)
- return -ENOENT;
-
- qobj = gem_to_virtio_gpu_obj(gobj);
+ long timeout = 15 * HZ;

if (args->flags & VIRTGPU_WAIT_NOWAIT)
- nowait = true;
- ret = virtio_gpu_object_wait(qobj, nowait);
+ timeout = 0;

- drm_gem_object_put_unlocked(gobj);
- return ret;
+ return drm_gem_reservation_object_wait(file, args->handle,
+ true, timeout);
}

static int virtio_gpu_get_caps_ioctl(struct drm_device *dev,
--
2.18.1

2019-06-17 14:17:27

by Daniel Vetter

Subject: Re: [PATCH 2/4] drm/virtio: switch virtio_gpu_wait_ioctl() to gem helper.

On Mon, Jun 17, 2019 at 01:14:04PM +0200, Gerd Hoffmann wrote:
> Use drm_gem_reservation_object_wait() in virtio_gpu_wait_ioctl().

Would be good to mention here that with this the wait becomes lockless, we
don't call ttm_bo_reserve/unreserve anymore.

> Signed-off-by: Gerd Hoffmann <[email protected]>
> ---
> drivers/gpu/drm/virtio/virtgpu_ioctl.c | 18 ++++--------------
> 1 file changed, 4 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> index c0ba1ead740f..e38a6bb46cc7 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> @@ -464,23 +464,13 @@ static int virtio_gpu_wait_ioctl(struct drm_device *dev, void *data,
> struct drm_file *file)
> {
> struct drm_virtgpu_3d_wait *args = data;
> - struct drm_gem_object *gobj = NULL;
> - struct virtio_gpu_object *qobj = NULL;
> - int ret;
> - bool nowait = false;
> -
> - gobj = drm_gem_object_lookup(file, args->handle);
> - if (gobj == NULL)
> - return -ENOENT;
> -
> - qobj = gem_to_virtio_gpu_obj(gobj);
> + long timeout = 15 * HZ;
>
> if (args->flags & VIRTGPU_WAIT_NOWAIT)
> - nowait = true;
> - ret = virtio_gpu_object_wait(qobj, nowait);
> + timeout = 0;

timeout of 0 gets upgrade to a 1 jiffy wait, which is probably not what
you want here. You need to open-code ttm_bo_wait here and call
reservation_object_test_signaled_rcu() for this case.

With that fixed Reviewed-by: Daniel Vetter <[email protected]>

>
> - drm_gem_object_put_unlocked(gobj);
> - return ret;
> + return drm_gem_reservation_object_wait(file, args->handle,
> + true, timeout);
> }
>
> static int virtio_gpu_get_caps_ioctl(struct drm_device *dev,
> --
> 2.18.1
>

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch