linux-kernel - Re: [PATCH] drm: don't check modeset locks in panic handler

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Date:	Thu, 2 May 2013 12:13:08 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Daniel Vetter <daniel.vetter@...ll.ch>
Cc:	DRI Development <dri-devel@...ts.freedesktop.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Dave Airlie <airlied@...il.com>, stable@...r.kernel.org
Subject: Re: [PATCH] drm: don't check modeset locks in panic handler

On Thu, May 02, 2013 at 09:43:05AM +0200, Daniel Vetter wrote:
> Since we know that locking is broken in that case and it's more
> important to not flood the dmesg with random gunk.
> 
> Cc: Dave Airlie <airlied@...il.com>
> Cc: Borislav Petkov <bp@...en8.de>
> References: https://groups.google.com/forum/?fromgroups=#!topic/linux.kernel/QFzFxSUeV4I

Yeah, we have this nice redirector service on k.org which uses the
Message-ID only and doesn't rely on some external URLs remaining stable.
You could use that instead:

Link: http://lkml.kernel.org/r/20130502000206.GH15623@pd.tnic

> Cc: stable@...r.kernel.org
> Signed-off-by: Daniel Vetter <daniel.vetter@...ll.ch>
> ---
>  drivers/gpu/drm/drm_crtc.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index 792c3e3..3be0802 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -78,6 +78,10 @@ void drm_warn_on_modeset_not_all_locked(struct drm_device *dev)
>  {
>  	struct drm_crtc *crtc;
>  
> +	/* Locking is currently fubar in the panic handler. */
> +	if (oops_in_progress)
> +		return;
> +
>  	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head)
>  		WARN_ON(!mutex_is_locked(&crtc->mutex));

Yep, thanks.

Reported-and-tested-by: Borislav Petkov <bp@...e.de>

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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