linux-kernel - Re: [PATCH v2 2/2] drm/qxl: add drm

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Date:   Mon, 10 Feb 2020 16:06:33 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Gerd Hoffmann <kraxel@...hat.com>
Cc:     dri-devel@...ts.freedesktop.org, Dave Airlie <airlied@...hat.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" 
        <virtualization@...ts.linux-foundation.org>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" 
        <spice-devel@...ts.freedesktop.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] drm/qxl: add drm_driver.release callback.

On Mon, Feb 10, 2020 at 12:37:52PM +0100, Gerd Hoffmann wrote:
> Move final cleanups to qxl_drm_release() callback.
> Add drm_atomic_helper_shutdown() call to qxl_pci_remove().
> 
> Signed-off-by: Gerd Hoffmann <kraxel@...hat.com>
> ---
>  drivers/gpu/drm/qxl/qxl_drv.c | 26 +++++++++++++++++++-------
>  1 file changed, 19 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/qxl/qxl_drv.c b/drivers/gpu/drm/qxl/qxl_drv.c
> index 1d601f57a6ba..4fda3f9b29f4 100644
> --- a/drivers/gpu/drm/qxl/qxl_drv.c
> +++ b/drivers/gpu/drm/qxl/qxl_drv.c
> @@ -34,6 +34,7 @@
>  #include <linux/pci.h>
>  
>  #include <drm/drm.h>
> +#include <drm/drm_atomic_helper.h>
>  #include <drm/drm_drv.h>
>  #include <drm/drm_file.h>
>  #include <drm/drm_modeset_helper.h>
> @@ -132,21 +133,30 @@ qxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>  	return ret;
>  }
>  
> +static void qxl_drm_release(struct drm_device *dev)
> +{
> +	struct qxl_device *qdev = dev->dev_private;
> +
> +	/*
> +	 * TODO: qxl_device_fini() call should be in qxl_pci_remove(),
> +	 * reodering qxl_modeset_fini() + qxl_device_fini() calls is
> +	 * non-trivial though.
> +	 */
> +	qxl_modeset_fini(qdev);

So the drm_mode_config_cleanup call in here belongs in ->release, but the
qxl_destroy_monitors_object feels like should be perfectly fine in the
remove hook. You might need to sprinkle a few drm_dev_enter/exit around to
protect code paths thought.

Aside from this lgtm, for the series

Acked-by: Daniel Vetter <daniel.vetter@...ll.ch>

And up to you whether you want to fix this or not really.

Btw for testing all these patches that add a ->release hook I think it'd
be good if the drm core checks that drm_device->dev is set to NULL, and
that we do this in the remove hook. Since that's guaranteed to be gone at
that point, so anything in ->release that still needs the device is
broken. Ofc maybe do that check only for drivers which have a ->release
hook, and we might need a few fixups.

Cheers, Daniel

> +	qxl_device_fini(qdev);
> +	dev->dev_private = NULL;
> +	kfree(qdev);
> +}
> +
>  static void
>  qxl_pci_remove(struct pci_dev *pdev)
>  {
>  	struct drm_device *dev = pci_get_drvdata(pdev);
> -	struct qxl_device *qdev = dev->dev_private;
>  
>  	drm_dev_unregister(dev);
> -
> -	qxl_modeset_fini(qdev);
> -	qxl_device_fini(qdev);
> +	drm_atomic_helper_shutdown(dev);
>  	if (is_vga(pdev))
>  		vga_put(pdev, VGA_RSRC_LEGACY_IO);
> -
> -	dev->dev_private = NULL;
> -	kfree(qdev);
>  	drm_dev_put(dev);
>  }
>  
> @@ -279,6 +289,8 @@ static struct drm_driver qxl_driver = {
>  	.major = 0,
>  	.minor = 1,
>  	.patchlevel = 0,
> +
> +	.release = qxl_drm_release,
>  };
>  
>  static int __init qxl_init(void)
> -- 
> 2.18.1
> 

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