From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Hurley <peter@hurleysoftware.com>
Subject: Re: [PATCH] drm: Assert correct locking for
	drm_send_vblank_event
Date: Fri, 12 Sep 2014 13:03:51 -0400
Message-ID: <54132777.5080804@hurleysoftware.com>
References: <1410529256-8602-1-git-send-email-daniel.vetter@ffwll.ch>
 <20140912152329.GI16043@nuc-i3427.alporthouse.com>
 <20140912153456.GH4740@phenom.ffwll.local>
 <20140912160442.GA14793@nuc-i3427.alporthouse.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <intel-gfx-bounces@lists.freedesktop.org>
In-Reply-To: <20140912160442.GA14793@nuc-i3427.alporthouse.com>
List-Unsubscribe: <http://lists.freedesktop.org/mailman/options/intel-gfx>,
 <mailto:intel-gfx-request@lists.freedesktop.org?subject=unsubscribe>
List-Archive: <http://lists.freedesktop.org/archives/intel-gfx>
List-Post: <mailto:intel-gfx@lists.freedesktop.org>
List-Help: <mailto:intel-gfx-request@lists.freedesktop.org?subject=help>
List-Subscribe: <http://lists.freedesktop.org/mailman/listinfo/intel-gfx>,
 <mailto:intel-gfx-request@lists.freedesktop.org?subject=subscribe>
Errors-To: intel-gfx-bounces@lists.freedesktop.org
Sender: "Intel-gfx" <intel-gfx-bounces@lists.freedesktop.org>
To: Chris Wilson <chris@chris-wilson.co.uk>, Daniel Vetter <daniel@ffwll.ch>, Daniel Vetter <daniel.vetter@ffwll.ch>, Intel Graphics Development <intel-gfx@lists.freedesktop.org>, dri-devel@lists.freedesktop.org
List-Id: intel-gfx@lists.freedesktop.org

On 09/12/2014 12:04 PM, Chris Wilson wrote:
> On Fri, Sep 12, 2014 at 05:34:56PM +0200, Daniel Vetter wrote:
>> On Fri, Sep 12, 2014 at 04:23:29PM +0100, Chris Wilson wrote:
>>> On Fri, Sep 12, 2014 at 03:40:56PM +0200, Daniel Vetter wrote:
>>>> The comment says that the caller must hold the dev->event_lock
>>>> spinlock, so let's enforce this.
>>>>
>>>> A quick audit over all driver shows that except for the one place in
>>>> i915 which motivated this all callers fullfill this requirement
>>>> already.
>>>
>>> Replace the rogue WARN_ON_SMP(!spin_is_locked(&dev->event_lock)) in
>>> send_vblank_event() as well then.
>>
>> Meh, I've missed that one, that's actually better I think. I'll drop my
>> patch here.
> 
> I thought assert_spin_lock was the preferred form?

Actually, lockdep_assert_held() is the preferred form.

See https://lkml.org/lkml/2014/9/3/171

Regards,
Peter Hurley