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From:   Brian Norris <briannorris@chromium.org>
Date:   Fri, 24 Jun 2022 10:57:53 -0700
Message-ID: <CA+ASDXOzhoooDDJUWV7rKpz-7GkMR5v=3gKQt4XazTSgnY51WQ@mail.gmail.com>
Subject: Re: [PATCH] drm/rockchip: vop: Don't crash for invalid duplicate_state()
To:     Heiko Stuebner <heiko@sntech.de>
Cc:     Doug Anderson <dianders@chromium.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        David Airlie <airlied@linux.ie>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@lists.infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Sandy Huang <hjc@rock-chips.com>,
        Sean Paul <seanpaul@chromium.org>
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On Fri, Jun 24, 2022 at 12:23 AM Heiko Stuebner <heiko@sntech.de> wrote:
> The interesting question would be, do we want some fixes tag for it?

I'm not aware of any currently-upstream code that will hit this [1].
I've hit it in out-of-tree code (or, code that I submitted to
dri-devel, but wasn't accepted as-is), and this is the "belt and
braces" part -- the primary fix is that we should avoid calling things
like drm_atomic_get_crtc_state() at inappropriate times.

So, is the "extra safety" check really something that should go to
-stable? (Because let's be honest, everything with a Fixes tag goes
there.) Maybe?

Anyway, if you want to "blame" anything, this commit actually dropped
the safety check:

4e257d9eee23 drm/rockchip: get rid of rockchip_drm_crtc_mode_config

Brian

[1] But I'm not omniscient. So maybe it's good to have anyway.