linux-kernel - Re: [RFC v3 01/11] drm/vblank: Register drmm cleanup action once per drm_vblank

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Date:   Tue, 21 Apr 2020 14:29:52 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Lyude Paul <lyude@...hat.com>
Cc:     dri-devel@...ts.freedesktop.org, Daniel Vetter <daniel@...ll.ch>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>, linux-kernel@...r.kernel.org
Subject: Re: [RFC v3 01/11] drm/vblank: Register drmm cleanup action once per
 drm_vblank_crtc

On Fri, Apr 17, 2020 at 03:40:48PM -0400, Lyude Paul wrote:
> Since we'll be allocating resources for kthread_create_worker() in the
> next commit (which could fail and require us to clean up the mess),
> let's simplify the cleanup process a bit by registering a
> drm_vblank_init_release() action for each drm_vblank_crtc so they're
> still cleaned up if we fail to initialize one of them.
> 
> Signed-off-by: Lyude Paul <lyude@...hat.com>
> ---
>  drivers/gpu/drm/drm_vblank.c | 22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
> index 758bf74e1cab..bf8de10c131f 100644
> --- a/drivers/gpu/drm/drm_vblank.c
> +++ b/drivers/gpu/drm/drm_vblank.c
> @@ -491,16 +491,12 @@ static void vblank_disable_fn(struct timer_list *t)
>  
>  static void drm_vblank_init_release(struct drm_device *dev, void *ptr)
>  {
> -	unsigned int pipe;
> -
> -	for (pipe = 0; pipe < dev->num_crtcs; pipe++) {
> -		struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
> +	struct drm_vblank_crtc *vblank = ptr;
>  
> -		WARN_ON(READ_ONCE(vblank->enabled) &&
> -			drm_core_check_feature(dev, DRIVER_MODESET));
> +	WARN_ON(READ_ONCE(vblank->enabled) &&
> +		drm_core_check_feature(dev, DRIVER_MODESET));
>  
> -		del_timer_sync(&vblank->disable_timer);
> -	}
> +	del_timer_sync(&vblank->disable_timer);
>  }
>  
>  /**
> @@ -529,10 +525,6 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs)
>  
>  	dev->num_crtcs = num_crtcs;
>  
> -	ret = drmm_add_action(dev, drm_vblank_init_release, NULL);
> -	if (ret)
> -		return ret;
> -
>  	for (i = 0; i < num_crtcs; i++) {
>  		struct drm_vblank_crtc *vblank = &dev->vblank[i];
>  
> @@ -541,6 +533,12 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs)
>  		init_waitqueue_head(&vblank->queue);
>  		timer_setup(&vblank->disable_timer, vblank_disable_fn, 0);
>  		seqlock_init(&vblank->seqlock);
> +
> +		ret = drmm_add_action(dev, drm_vblank_init_release, vblank);

drmm_add_action_or_reset probably what you want. I've gone so far an
unexport the plain variant.
-Daniel

> +		if (ret) {
> +			del_timer_sync(&vblank->disable_timer);
> +			return ret;
> +		}
>  	}
>  
>  	DRM_INFO("Supports vblank timestamp caching Rev 2 (21.10.2013).\n");
> -- 
> 2.25.1
> 

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