linux-kernel - Re: [PATCH] drm/bochs: add drm

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Message-ID: <20200207134225.GA43062@phenom.ffwll.local>
Date:   Fri, 7 Feb 2020 14:42:25 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Gerd Hoffmann <kraxel@...hat.com>
Cc:     dri-devel@...ts.freedesktop.org,
        Gurchetan Singh <gurchetansingh@...omium.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        "open list:DRM DRIVER FOR BOCHS VIRTUAL GPU" 
        <virtualization@...ts.linux-foundation.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/bochs: add drm_driver.release callback.

On Fri, Feb 07, 2020 at 01:13:12PM +0100, Gerd Hoffmann wrote:
> From: Gurchetan Singh <gurchetansingh@...omium.org>
> 
> Move bochs_unload call from bochs_remove() to the new bochs_release()
> callback.  Also call drm_dev_unregister() first in bochs_remove().
> 
> Signed-off-by: Gerd Hoffmann <kraxel@...hat.com>
> ---
>  drivers/gpu/drm/bochs/bochs_drv.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bochs/bochs_drv.c b/drivers/gpu/drm/bochs/bochs_drv.c
> index 10460878414e..87ee1eb21a4d 100644
> --- a/drivers/gpu/drm/bochs/bochs_drv.c
> +++ b/drivers/gpu/drm/bochs/bochs_drv.c
> @@ -60,6 +60,11 @@ static int bochs_load(struct drm_device *dev)
>  
>  DEFINE_DRM_GEM_FOPS(bochs_fops);
>  
> +static void bochs_release(struct drm_device *dev)
> +{
> +	bochs_unload(dev);

Hm I think this needs to be split, and bochs_hw_fini needs to stay in
bochs_pci_remove. Otherwise we again release the iommu mappings too late
(there was just a discussion about that on the fbdev side of things
getting this wrong). Good to fix the lifetime fun here, but let's not move
too far :-)

Ideally we'd move the iomapping to devm_, that would remove it at the
right time I think.

Slight annoyance might be that we then need to shoot down the varios
mmaps, which I frankly don't know how to do. But keeping them pointing at
wrong stuff also isn't that great :-/

Cheers, Daniel

> +}
> +
>  static struct drm_driver bochs_driver = {
>  	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
>  	.fops			= &bochs_fops,
> @@ -69,6 +74,7 @@ static struct drm_driver bochs_driver = {
>  	.major			= 1,
>  	.minor			= 0,
>  	DRM_GEM_VRAM_DRIVER,
> +	.release                = bochs_release,
>  };
>  
>  /* ---------------------------------------------------------------------- */
> @@ -148,9 +154,8 @@ static void bochs_pci_remove(struct pci_dev *pdev)
>  {
>  	struct drm_device *dev = pci_get_drvdata(pdev);
>  
> -	drm_atomic_helper_shutdown(dev);
>  	drm_dev_unregister(dev);
> -	bochs_unload(dev);
> +	drm_atomic_helper_shutdown(dev);
>  	drm_dev_put(dev);
>  }
>  
> -- 
> 2.18.1
> 

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