[PATCH] drm/exynos: fix kernel panic issue at drm releasing

[Inki Dae]

Hi Daniel,

2016년 01월 05일 05:24에 Daniel Stone 이(가) 쓴 글:
> Hi Inki,
> 
> On 4 January 2016 at 12:57, Inki Dae <inki.dae at samsung.com> wrote:
>> 2015년 12월 24일 22:32에 Daniel Stone 이(가) 쓴 글:
>>> On 24 December 2015 at 09:10, Inki Dae <inki.dae at samsung.com> wrote:
>>>> +void exynos_drm_crtc_cancel_page_flip(struct drm_crtc *crtc)
>>>> +{
>>>> +       struct exynos_drm_crtc *exynos_crtc = to_exynos_crtc(crtc);
>>>> +       unsigned long flags;
>>>> +
>>>> +       spin_lock_irqsave(&crtc->dev->event_lock, flags);
>>>> +       exynos_crtc->event = NULL;
>>>> +       spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
>>>> +}
>>>
>>> This will leak the event and event space; you should call
>>> event->base.destroy() here. With that fixed:
>>
>> Right. we don't use exynos specific page flip function anymore which managed 
>> the event as a list so that the event objects can be freed by postclose 
>> callback.
>> Anyway, would it be better for event->base.destory() to be called between 
>> spin lock/unlock?
> 
> You must increment event->base.file_priv->event_space (see
> drm_atomic.c:destroy_vblank_event), as well as calling

Reasonable to me. Seems other DRM drivers don't increment event_space.

> event->base.destroy (see drm_fops.c:drm_read) underneath event_lock,
> yes.

In addition, only event objects belonging to the request process should be 
destroyed.

Thanks,
Inki Dae

> 
> Cheers,
> Daniel
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