[Issue]: dkms: false positive in HDMI/DP colorspace property checks due to missing AC_KERNEL_DO_BACKGROUND

[theSprog]

Problem Description

Issue Description
The DKMS configure script produces false positives for drm_mode_create_hdmi_colorspace_property and drm_mode_create_dp_colorspace_property on older kernels (e.g., v5.17) that only support the 1-argument version of these functions.

Latent Bug Nature & Reproduction
This bug is currently masked in the vanilla AMDGPU tree purely due to macro execution order (preceding foreground tests happen to fail or not leave a valid conftest.o). However, it reliably breaks downstream forks or custom backports that introduce a successful foreground macro just before these colorspace checks.

Time-oriented Execution Flow & Root Cause
The issue stems from a missing sandbox isolation wrapper, which causes a sequential state contamination when combined with the Kbuild toolchain.

1. State Contamination: A prior synchronous test in the configuration sequence succeeds, leaving a valid conftest.o in the top-level build directory.
2. Missing Sandbox: AC_AMDGPU_DRM_MODE_CREATE_HDMI_COLORSPACE_PROPERTY is executed. Because it lacks the AC_KERNEL_DO_BACKGROUND wrapper, it runs synchronously in the same polluted top-level directory instead of a clean, isolated temporary directory (mktemp -d).
3. Compiler Failure: gcc fails to compile the 2-argument test code due to argument mismatch and exits. It does not overwrite or generate a new conftest.o.
4. Pipeline Deception: In x86 Kbuild environments, the compilation pipeline captured in $CFLAGS chains objtool execution with a semicolon (e.g., gcc ... -c -o conftest.o conftest.c ; objtool check ... conftest.o). The shell ignores gcc's exit code.
5. False Positive: objtool runs, validates the stale conftest.o left by step 1, and returns 0. AC_KERNEL_COMPILE_IFELSE catches this 0 and incorrectly defines HAVE_DRM_MODE_CREATE_HDMI_COLORSPACE_PROPERTY_2ARGS.

Suggested Fix
Wrap the affected macros in AC_KERNEL_DO_BACKGROUND to align with the existing concurrent probing architecture. This ensures they execute in ephemeral, isolated directories, completely avoiding stale object files.

--- a/m4/drm_mode_create_hdmi_colorspace_property.m4
+++ b/m4/drm_mode_create_hdmi_colorspace_property.m4
@@ -1,13 +1,15 @@
 AC_DEFUN([AC_AMDGPU_DRM_MODE_CREATE_HDMI_COLORSPACE_PROPERTY], [
-    AC_KERNEL_TRY_COMPILE_SYMBOL([
-            #include <drm/drm_connector.h>
-        ], [
-            drm_mode_create_hdmi_colorspace_property(NULL, 0);
-        ], [drm_mode_create_hdmi_colorspace_property], [drivers/gpu/drm/drm_connector.c], [
-                AC_DEFINE(HAVE_DRM_MODE_CREATE_HDMI_COLORSPACE_PROPERTY_2ARGS, 1,
-                        [drm_mode_create_hdmi_colorspace_property() has 2 args])
-        ])
+    AC_KERNEL_DO_BACKGROUND([
+        AC_KERNEL_TRY_COMPILE_SYMBOL([
+                #include <drm/drm_connector.h>
+            ], [
+                drm_mode_create_hdmi_colorspace_property(NULL, 0);
+            ], [drm_mode_create_hdmi_colorspace_property], [drivers/gpu/drm/drm_connector.c], [
+                    AC_DEFINE(HAVE_DRM_MODE_CREATE_HDMI_COLORSPACE_PROPERTY_2ARGS, 1,
+                            [drm_mode_create_hdmi_colorspace_property() has 2 args])
+            ])
+    ])
 ]) 
 
 dnl #
@@ -15,12 +17,14 @@
 dnl # drm/connector: Allow drivers to pass list of supported colorspaces
 dnl #
 AC_DEFUN([AC_AMDGPU_DRM_MODE_CREATE_DP_COLORSPACE_PROPERTY], [
-    AC_KERNEL_TRY_COMPILE_SYMBOL([
-            #include <drm/drm_connector.h>
-        ], [
-            drm_mode_create_dp_colorspace_property(NULL, 0);
-        ], [drm_mode_create_dp_colorspace_property], [drivers/gpu/drm/drm_connector.c], [
-                AC_DEFINE(HAVE_DRM_MODE_CREATE_DP_COLORSPACE_PROPERTY_2ARGS, 1,
-                        [drm_mode_create_dp_colorspace_property() has 2 args])
-        ])
+    AC_KERNEL_DO_BACKGROUND([
+        AC_KERNEL_TRY_COMPILE_SYMBOL([
+                #include <drm/drm_connector.h>
+            ], [
+                drm_mode_create_dp_colorspace_property(NULL, 0);
+            ], [drm_mode_create_dp_colorspace_property], [drivers/gpu/drm/drm_connector.c], [
+                    AC_DEFINE(HAVE_DRM_MODE_CREATE_DP_COLORSPACE_PROPERTY_2ARGS, 1,
+                            [drm_mode_create_dp_colorspace_property() has 2 args])
+            ])
+    ])
 ])

Operating System

Linux 5.17

CPU

Hygon C86-3G

GPU

None

ROCm Version

ROCm 6.0.0

ROCm Component

No response

Steps to Reproduce

No response

(Optional for Linux users) Output of /opt/rocm/bin/rocminfo --support

rocminfo --support output

Paste output here

Additional Information

No response