From: Markus Elfring <Markus.Elfring@web.de>
To: Dan Carpenter <dan.carpenter@linaro.org>,
Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
kernel-janitors@vger.kernel.org, freedreno@lists.freedesktop.org,
dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org
Cc: Abhinav Kumar <quic_abhinavk@quicinc.com>,
Archit Taneja <architt@codeaurora.org>,
Daniel Vetter <daniel@ffwll.ch>, David Airlie <airlied@gmail.com>,
Jeykumar Sankaran <jsanka@codeaurora.org>,
Jordan Crouse <jordan@cosmicpenguin.net>,
Marijn Suijten <marijn.suijten@somainline.org>,
Rob Clark <robdclark@gmail.com>, Sean Paul <sean@poorly.run>,
Simona Vetter <simona@ffwll.ch>, Vinod Koul <vkoul@kernel.org>,
cocci@inria.fr, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] Clarification for “undefined behaviour”?
Date: Wed, 5 Mar 2025 09:40:43 +0100 [thread overview]
Message-ID: <e665514b-5a62-4afb-b267-7c320e4872af@web.de> (raw)
In-Reply-To: <29b32b0d-312d-4848-9e26-9e5e76e527a7@stanley.mountain>
>>> The address of a data structure member was determined before
>>> a corresponding null pointer check in the implementation of
>>> the functions “dpu_hw_pp_enable_te” and “dpu_hw_pp_get_vsync_info”.
>>>
>>> Thus avoid the risk for undefined behaviour by removing extra
>>> initialisations for the variable “c” (also because it was already
>>> reassigned with the same value behind this pointer check).
> There is no undefined behavior here.
Is there a need to improve the wording precision?
There are words which denote a special meaning according to aspects of
the programming language “C”.
https://en.cppreference.com/w/c/language/behavior
Dereferences of null pointers are treated in special ways.
The system might be configurable to collaborate also with data accesses
together with the address “zero”.
Would you like to distinguish supported software functionality any further?
Regards,
Markus
next prev parent reply other threads:[~2025-03-05 8:41 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <40c60719-4bfe-b1a4-ead7-724b84637f55@web.de>
[not found] ` <1a11455f-ab57-dce0-1677-6beb8492a257@web.de>
2023-04-11 13:36 ` [PATCH 0/5] drm/amd: Adjustments for three function implementations Markus Elfring
2023-04-11 13:42 ` [PATCH 1/5] drm/amdgpu: Move a variable assignment behind a null pointer check in amdgpu_ras_interrupt_dispatch() Markus Elfring
2023-04-11 13:59 ` Felix Kuehling
2023-04-11 14:45 ` Markus Elfring
2024-09-09 9:42 ` Markus Elfring
2023-04-11 13:43 ` [PATCH 2/5] drm/amd/display: Move three variable assignments behind condition checks in trigger_hotplug() Markus Elfring
2023-04-11 15:04 ` Christian König
2023-05-16 16:40 ` Markus Elfring
2023-04-11 13:46 ` [PATCH 3/5] drm/amd/display: Delete three unnecessary variable initialisations " Markus Elfring
2023-04-11 13:48 ` [PATCH 4/5] drm/amd/display: Delete a redundant statement " Markus Elfring
2023-04-11 13:50 ` [PATCH 5/5] drm/amd/display: Move an expression into a return statement in dcn201_link_encoder_create() Markus Elfring
2024-01-05 19:21 ` [PATCH 0/5] drm/amd: Adjustments for three function implementations Markus Elfring
2023-04-11 16:38 ` [PATCH] drm/msm/dpu: Delete a variable initialisation before a null pointer check in two functions Markus Elfring
2023-04-11 16:43 ` Dmitry Baryshkov
2023-04-11 16:44 ` Abhinav Kumar
2025-03-02 20:56 ` [PATCH RESEND] " Markus Elfring
2025-03-02 23:01 ` Dmitry Baryshkov
2025-03-03 7:14 ` Dan Carpenter
2025-03-03 8:15 ` [RESEND] " Markus Elfring
2025-03-03 8:24 ` Dan Carpenter
2025-03-05 8:40 ` Markus Elfring [this message]
2025-03-05 8:51 ` [RFC] Clarification for “undefined behaviour”? Dan Carpenter
2025-03-05 9:20 ` Markus Elfring
2025-03-05 14:17 ` David Laight
2025-03-05 14:30 ` Dan Carpenter
2025-03-05 21:35 ` David Laight
2023-04-13 19:44 ` [PATCH] video: au1100fb: Move a variable assignment behind a null pointer check in au1100fb_setmode() Markus Elfring
2025-03-02 18:02 ` [PATCH RESEND] " Markus Elfring
2025-03-03 9:19 ` Uwe Kleine-König
2025-03-03 10:08 ` Dan Carpenter
2025-03-03 10:08 ` Dan Carpenter
2025-03-03 10:14 ` Dan Carpenter
2025-03-03 10:30 ` Uwe Kleine-König
2025-03-03 10:36 ` Markus Elfring
2025-03-03 10:53 ` [PATCH RESEND] " Dan Carpenter
2025-03-05 12:14 ` Markus Elfring
2025-03-05 17:07 ` Helge Deller
2025-03-05 17:28 ` Markus Elfring
2025-03-08 21:26 ` [PATCH RESEND] " Helge Deller
2023-04-16 9:30 ` [PATCH 0/9] GPU-DRM-nouveau: Adjustments for seven function implementations Markus Elfring
2023-04-16 9:33 ` [PATCH 1/9] drm/nouveau/debugfs: Move an expression into a function call parameter in nouveau_debugfs_pstate_set() Markus Elfring
2023-04-16 9:36 ` [PATCH 2/9] drm/nouveau/debugfs: Move a variable assignment behind a null pointer check in nouveau_debugfs_pstate_get() Markus Elfring
2023-04-16 9:38 ` [PATCH 3/9] drm/nouveau/debugfs: Use seq_putc() " Markus Elfring
2023-04-16 9:40 ` [PATCH 4/9] drm/nouveau/debugfs: Replace five seq_printf() calls by seq_puts() " Markus Elfring
2023-04-16 9:42 ` [PATCH 5/9] drm/nouveau/bios/power_budget: Move an expression into a macro call parameter in nvbios_power_budget_header() Markus Elfring
2023-04-16 9:44 ` [PATCH 6/9] drm/nouveau/clk: Move a variable assignment behind a null pointer check in nvkm_pstate_new() Markus Elfring
2023-04-16 9:46 ` [PATCH 7/9] drm/nouveau/pci: Move a variable assignment behind condition checks in nvkm_pcie_set_link() Markus Elfring
2023-04-16 9:54 ` [PATCH 8/9] drm/nouveau/pci: Move an expression into a function call parameter " Markus Elfring
2023-04-16 9:56 ` [PATCH 9/9] drm/nouveau/therm: Move an assignment statement behind a null pointer check in two functions Markus Elfring
2023-04-17 16:25 ` [PATCH 0/9] GPU-DRM-nouveau: Adjustments for seven function implementations Karol Herbst
2023-04-16 15:47 ` [PATCH] drm/bridge: it6505: Move a variable assignment behind a null pointer check in receive_timing_debugfs_show() Markus Elfring
2023-04-25 13:30 ` Robert Foss
2023-04-25 14:15 ` Markus Elfring
2023-04-27 15:10 ` Robert Foss
2023-04-27 19:34 ` Markus Elfring
2023-04-28 11:49 ` Robert Foss
2023-04-28 15:55 ` [PATCH resent] " Markus Elfring
2023-04-28 17:27 ` Robert Foss
2023-04-17 9:42 ` [PATCH] drm/mm: Adjust input parameter validation in DECLARE_NEXT_HOLE_ADDR() Markus Elfring
2025-03-03 12:48 ` [PATCH RESEND] " Markus Elfring
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