Bug#1148283: [PATCH] nvidia-kernel-dkms: fix build with Linux 7.2 (strncpy removal, drm_atomic_commit rename)

[Kevin Cuevas]

Control: tags -1 + patch

Hi,

Attached is a patch against nvidia-graphics-drivers 550.163.01-5.1 that
makes
nvidia-kernel-dkms build and work on Linux 7.2.6+deb14-amd64. It addresses
the
two issues Jonas described in his follow-up to this bug.

1. strncpy() removed in Linux 7.2

   - nvidia/os-interface.c and nvidia-uvm/uvm_pmm_gpu.c: switched to
strscpy(),
     same as NVIDIA's upstream fix (open-gpu-kernel-modules PR #1227,
shipped
     in 610.57.04).
   - nvidia/linux_nvswitch.c (registry key parsing): switched to memcpy(),
also
     as upstream does. The following line already NUL-terminates.
   - nvkms_strncpy() and nvswitch_os_strncpy(): these are called from the
     closed-source binary objects, so, following the concern raised in this
     bug, I kept their names and exact strncpy() semantics (copy, then
     zero-pad the rest of the buffer), implemented locally instead of
changing
     them to strscpy().

2. struct drm_atomic_state renamed to struct drm_atomic_commit
   (commit 5164f7e7ff8e)

   - New conftest drm_atomic_commit_present (types), registered in
     nvidia-drm-sources.mk. It uses sizeof(struct drm_atomic_commit), so it
     cannot give a false positive on older kernels.
   - When it is defined, nvidia-drm-conftest.h maps the old names to the new
     API (drm_atomic_state_alloc/clear/get/put/init/default_clear/
     default_release -> drm_atomic_commit_*). I checked these names against
     the 7.2.6 headers.
   - Several existing conftests probe using the old struct name and silently
     report false negatives on 7.2. That made the driver pick the pre-4.10
     code paths (drm_atomic_state_free, and the old signatures of the crtc
and
     plane atomic_check callbacks). When NV_DRM_ATOMIC_COMMIT_PRESENT is
set,
     the patch forces ATOMIC_STATE_REF_COUNTING_PRESENT,
     CRTC/PLANE_ATOMIC_CHECK_HAS_ATOMIC_STATE_ARG and the two
     ATOMIC_HELPER_SWAP_STATE conftests.

   Everything new is guarded by NV_DRM_ATOMIC_COMMIT_PRESENT, so builds on
   older kernels are unchanged.

Testing:

- Built with DKMS against 7.2.6+deb14-amd64 and 7.1.13+deb14-amd64. Both
  succeed with no errors and no implicit-declaration or modpost warnings.
  On 7.1.13 the new conftest correctly reports #undef.
- Hardware: HP laptop with GeForce RTX 2050 (GA107, 10de:25ad) plus Radeon
  680M, KDE Plasma on Wayland, forky.
- Booted 7.2.6: nvidia, nvidia_modeset, nvidia_drm and nvidia_uvm load,
  nvidia-smi reports the GPU with driver 550.163.01, and the desktop works.

This is a local fix and I have only tested it on one machine, so please
review
it before using it. I hope it helps get a 7.2-compatible upload out.

Thanks,
Kevin Cuevas
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