linux-kernel - Re: [PATCH v2 02/12] drm/virtio: switch virtio_gpu_wait

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Message-ID: <20190618140704.GA12905@phenom.ffwll.local>
Date:   Tue, 18 Jun 2019 16:07:04 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Gerd Hoffmann <kraxel@...hat.com>
Cc:     dri-devel@...ts.freedesktop.org, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        "open list:VIRTIO GPU DRIVER" 
        <virtualization@...ts.linux-foundation.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 02/12] drm/virtio: switch virtio_gpu_wait_ioctl() to
 gem helper.

On Tue, Jun 18, 2019 at 03:58:10PM +0200, Gerd Hoffmann wrote:
> Use drm_gem_reservation_object_wait() in virtio_gpu_wait_ioctl().
> This also makes the ioctl run lockless.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@...hat.com>
> Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>

Nit: Missing the v2 changelog here.
-Daniel

> ---
>  drivers/gpu/drm/virtio/virtgpu_ioctl.c | 24 ++++++++++--------------
>  1 file changed, 10 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> index ac60be9b5c19..313c770ea2c5 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> @@ -464,23 +464,19 @@ 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;
> +	struct drm_gem_object *obj;
> +	long timeout = 15 * HZ;
>  	int ret;
> -	bool nowait = false;
>  
> -	gobj = drm_gem_object_lookup(file, args->handle);
> -	if (gobj == NULL)
> -		return -ENOENT;
> +	if (args->flags & VIRTGPU_WAIT_NOWAIT) {
> +		obj = drm_gem_object_lookup(file, args->handle);
> +		ret = reservation_object_test_signaled_rcu(obj->resv, true);
> +		drm_gem_object_put_unlocked(obj);
> +		return ret ? 0 : -EBUSY;
> +	}
>  
> -	qobj = gem_to_virtio_gpu_obj(gobj);
> -
> -	if (args->flags & VIRTGPU_WAIT_NOWAIT)
> -		nowait = true;
> -	ret = virtio_gpu_object_wait(qobj, nowait);
> -
> -	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