Re: [PATCH] drm/irq: BUG_ON() -> WARN_ON()

From: Jani Nikula <jani.nikula@linux.intel.com>
To: Rob Clark <robdclark@gmail.com>, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] drm/irq: BUG_ON() -> WARN_ON()
Date: Mon, 10 Nov 2014 13:01:25 +0200	[thread overview]
Message-ID: <87sihrz5dm.fsf@intel.com> (raw)
In-Reply-To: <1415459779-30961-1-git-send-email-robdclark@gmail.com>

On Sat, 08 Nov 2014, Rob Clark <robdclark@gmail.com> wrote:
> Let's make things a bit easier to debug when things go bad (potentially
> under console_lock).
>
> Signed-off-by: Rob Clark <robdclark@gmail.com>
> ---
>  drivers/gpu/drm/drm_irq.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
> index 5ef03c2..c4edea9 100644
> --- a/drivers/gpu/drm/drm_irq.c
> +++ b/drivers/gpu/drm/drm_irq.c
> @@ -1029,7 +1029,8 @@ void drm_vblank_put(struct drm_device *dev, int crtc)
>  {
>  	struct drm_vblank_crtc *vblank = &dev->vblank[crtc];
>  
> -	BUG_ON(atomic_read(&vblank->refcount) == 0);
> +	if (WARN_ON(atomic_read(&vblank->refcount) == 0))
> +		return;

While I approve of the change, I'd like to promote the use of WARN with
a message instead of WARN_ON. See [1]. In fact it lead to us redefining
WARN_ON in i915 [2].

Thanks,
Jani.

[1] http://mid.gmane.org/87y4sfkoy4.fsf@intel.com
[2] http://mid.gmane.org/1414510350-15713-1-git-send-email-miku@iki.fi

>  
>  	if (WARN_ON(crtc >= dev->num_crtcs))
>  		return;
> -- 
> 1.9.3
>
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-- 
Jani Nikula, Intel Open Source Technology Center
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