linux-kernel - Re: [PATCH] drm/irq: BUG_ON() -> WARN

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Message-ID: <5460A2A6.1020904@canonical.com>
Date:	Mon, 10 Nov 2014 12:33:58 +0100
From:	Maarten Lankhorst <maarten.lankhorst@...onical.com>
To:	Jani Nikula <jani.nikula@...ux.intel.com>,
	Rob Clark <robdclark@...il.com>,
	dri-devel@...ts.freedesktop.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/irq: BUG_ON() -> WARN_ON()

Hey,

Op 10-11-14 om 12:01 schreef Jani Nikula:
> On Sat, 08 Nov 2014, Rob Clark <robdclark@...il.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@...il.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].
I love the redefinition of WARN, but I think this should not be overridden locally, instead it should be a kernel debug option.

~Maarten

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