[PATCH 04/24] drm/vgem: Use devm_drm_dev_alloc

[Melissa Wen]

Hi Daniel,

looks good to me, just a few things inline.

On 09/04, Daniel Vetter wrote:
> This means we also need to slightly restructure the exit code, so that
> final cleanup of the drm_device is triggered by unregistering the
> platform device. Note that devres is both clean up when the driver is
> unbound (not the case for vgem, we don't bind), and also when unregistering
> the device (very much the case for vgem). Therefore we can rely on devres
> even though vgem isn't a proper platform device driver.
> 
> This also somewhat untangles the load code, since the drm and platform device
> setup are no longer interleaved, but two distinct steps.
> 
> v2: use devres_open/release_group so we can use devm without real
> hacks in the driver core or having to create an entire fake bus for
> testing drivers. Might want to extract this into helpers eventually,
> maybe as a mock_drm_dev_alloc or test_drm_dev_alloc.
> 
> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Emil Velikov <emil.velikov at collabora.com>
> Cc: Sean Paul <seanpaul at chromium.org>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Sam Ravnborg <sam at ravnborg.org>
> Cc: Rob Clark <robdclark at chromium.org>
> ---
>  drivers/gpu/drm/vgem/vgem_drv.c | 55 ++++++++++++++-------------------
>  1 file changed, 24 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> index 313339bbff90..f95537627463 100644
> --- a/drivers/gpu/drm/vgem/vgem_drv.c
> +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> @@ -401,16 +401,8 @@ static int vgem_prime_mmap(struct drm_gem_object *obj,
>  	return 0;
>  }
>  
> -static void vgem_release(struct drm_device *dev)
> -{
> -	struct vgem_device *vgem = container_of(dev, typeof(*vgem), drm);
> -
> -	platform_device_unregister(vgem->platform);
> -}
> -
>  static struct drm_driver vgem_driver = {
>  	.driver_features		= DRIVER_GEM | DRIVER_RENDER,
> -	.release			= vgem_release,
>  	.open				= vgem_open,
>  	.postclose			= vgem_postclose,
>  	.gem_free_object_unlocked	= vgem_gem_free_object,
> @@ -442,48 +434,49 @@ static struct drm_driver vgem_driver = {
>  static int __init vgem_init(void)
>  {
>  	int ret;
> +	struct platform_device *pdev;
>  
> -	vgem_device = kzalloc(sizeof(*vgem_device), GFP_KERNEL);
> -	if (!vgem_device)
> -		return -ENOMEM;
> +	pdev = platform_device_register_simple("vgem", -1, NULL, 0);
> +	if (IS_ERR(pdev))
> +		return PTR_ERR(vgem_device->platform);
I caught this line right above.
It should be: return PTR_ERR (pdev), right?
>  
> -	vgem_device->platform =
> -		platform_device_register_simple("vgem", -1, NULL, 0);
> -	if (IS_ERR(vgem_device->platform)) {
> -		ret = PTR_ERR(vgem_device->platform);
> -		goto out_free;
> +	if (!devres_open_group(&pdev->dev, NULL, GFP_KERNEL)) {
> +		ret = -ENOMEM;
> +		goto out_unregister;
>  	}
>  
> -	dma_coerce_mask_and_coherent(&vgem_device->platform->dev,
> +	dma_coerce_mask_and_coherent(&pdev->dev,
>  				     DMA_BIT_MASK(64));
> -	ret = drm_dev_init(&vgem_device->drm, &vgem_driver,
> -			   &vgem_device->platform->dev);
> -	if (ret)
> -		goto out_unregister;
> -	drmm_add_final_kfree(&vgem_device->drm, vgem_device);
> +
> +	vgem_device = devm_drm_dev_alloc(&pdev->dev, &vgem_driver,
> +					 struct vgem_device, drm);
> +	if (IS_ERR(vgem_device)) {
> +		ret = PTR_ERR(vgem_device);
> +		goto out_devres;
> +	}
> +	vgem_device->platform = pdev;
>  
>  	/* Final step: expose the device/driver to userspace */
>  	ret = drm_dev_register(&vgem_device->drm, 0);
>  	if (ret)
> -		goto out_put;
> +		goto out_devres;
>  
>  	return 0;
>  
> -out_put:
> -	drm_dev_put(&vgem_device->drm);
> -	platform_device_unregister(vgem_device->platform);
> -	return ret;
> +out_devres:
> +	devres_release_group(&pdev->dev, NULL);
>  out_unregister:
> -	platform_device_unregister(vgem_device->platform);
> -out_free:
> -	kfree(vgem_device);
> +	platform_device_unregister(pdev);
>  	return ret;
>  }
>  
>  static void __exit vgem_exit(void)
>  {
> +	struct platform_device *pdev = vgem_device->platform;
> +
Well, there has never been a check for a null vgem_device here before,
as in vkms. Should?
>  	drm_dev_unregister(&vgem_device->drm);
> -	drm_dev_put(&vgem_device->drm);
> +	devres_release_group(&pdev->dev, NULL);
> +	platform_device_unregister(pdev);
>  }
>  
>  module_init(vgem_init);
> -- 
> 2.28.0

Apart from these two points,

Reviewed-by: Melissa Wen <melissa.srw at gmail.com>

Thanks!
> 
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