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Message-ID: <436116c9-6ce4-87cc-b1cd-f44b72fcfb35@amd.com>
Date:   Fri, 8 Apr 2022 16:30:06 +0200
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Subject: Re: [PATCH] drm/amdgpu: Fix NULL pointer dereference
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To:     Grigory Vasilyev <h0tc0d3@gmail.com>,
        Simon Ser <contact@emersion.fr>
Cc:     Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>,
        Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>,
        Melissa Wen <mwen@igalia.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        "Pan, Xinhui" <Xinhui.Pan@amd.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        =?UTF-8?Q?Michel_D=c3=a4nzer?= <mdaenzer@redhat.com>,
        Evan Quan <evan.quan@amd.com>,
        Sean Paul <seanpaul@chromium.org>,
        Qingqing Zhuo <qingqing.zhuo@amd.com>,
        amd-gfx mailing list <amd-gfx@lists.freedesktop.org>,
        ML dri-devel <dri-devel@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>
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From:   =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>
In-Reply-To: <CAD5ugGD6QzCUqk7_EVwH9Cc6PQtx_VfjVRWzzP9uKR5tkGh1RQ@mail.gmail.com>
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Am 08.04.22 um 15:21 schrieb Grigory Vasilyev:
> Simon Ser and Bas Nieuwenhuizen, do you understand that you are
> proposing to make the code less safe in the future? In the future,
> someone might rewrite the code and we'll get an error.

Which is perfectly fine.

See error handling is to handle userspace or hardware errors and *not* 
coding errors.

Testing all pointers for NULL without any reason is not defensive, but 
rather the exactly opposite since it helps hiding real bugs.

Regards,
Christian.

>
> пт, 8 апр. 2022 г. в 14:48, Simon Ser <contact@emersion.fr>:
>> On Friday, April 8th, 2022 at 13:28, Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl> wrote:
>>
>>> On Fri, Apr 8, 2022 at 12:01 PM Simon Ser contact@emersion.fr wrote:
>>>
>>>> Is amdgpu_display_get_fb_info ever called with NULL tiling_flags/tmz_surface?
>>>> If not, there's no point in adding NULL checks.
>>> It isn't called with NULL anywhere, the NULL checks that already exist
>>> seem redundant.
>> Grigory, would be be willing to submit a v2 which removes the unnecessary
>> NULL checks?