Third round of Kbuild fixes for 6.19

- Strip trailing padding bytes from modules.builtin.modinfo to fix error
   during modules_install with certain versions of kmod
 
 - Drop unused static inline function warning in .c files with clang from
   W=1 to W=2
 
 - Ensure kernel-doc.py invocations use the PYTHON3 make variable to
   ensure user's choice of Python interpreter is always respected
 
 Signed-off-by: Nathan Chancellor <nathan@kernel.org>
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Merge tag 'kbuild-fixes-6.18-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux

Pull Kbuild fixes from Nathan Chancellor:

 - Strip trailing padding bytes from modules.builtin.modinfo to fix
   error during modules_install with certain versions of kmod

 - Drop unused static inline function warning in .c files with clang
   from W=1 to W=2

 - Ensure kernel-doc.py invocations use the PYTHON3 make variable to
   ensure user's choice of Python interpreter is always respected

* tag 'kbuild-fixes-6.18-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux:
  kbuild: Let kernel-doc.py use PYTHON3 override
  compiler_types: Move unused static inline functions warning to W=2
  kbuild: Strip trailing padding bytes from modules.builtin.modinfo

drivers/gpu/drm/Makefile

@@ -245,7 +245,7 @@ always-$(CONFIG_DRM_HEADER_TEST) += \
 quiet_cmd_hdrtest = HDRTEST $(patsubst %.hdrtest,%.h,$@)
       cmd_hdrtest = \
 		$(CC) $(c_flags) -fsyntax-only -x c /dev/null -include $< -include $<; \
-		 PYTHONDONTWRITEBYTECODE=1 $(KERNELDOC) -none $(if $(CONFIG_WERROR)$(CONFIG_DRM_WERROR),-Werror) $<; \
+		 PYTHONDONTWRITEBYTECODE=1 $(PYTHON3) $(KERNELDOC) -none $(if $(CONFIG_WERROR)$(CONFIG_DRM_WERROR),-Werror) $<; \
 		touch $@
 
 $(obj)/%.hdrtest: $(src)/%.h FORCE

drivers/gpu/drm/i915/Makefile

@@ -413,7 +413,7 @@ obj-$(CONFIG_DRM_I915_GVT_KVMGT) += kvmgt.o
 #
 # Enable locally for CONFIG_DRM_I915_WERROR=y. See also scripts/Makefile.build
 ifdef CONFIG_DRM_I915_WERROR
-    cmd_checkdoc = PYTHONDONTWRITEBYTECODE=1 $(KERNELDOC) -none -Werror $<
+    cmd_checkdoc = PYTHONDONTWRITEBYTECODE=1 $(PYTHON3) $(KERNELDOC) -none -Werror $<
 endif
 
 # header test

include/drm/Makefile

@@ -11,7 +11,7 @@ always-$(CONFIG_DRM_HEADER_TEST) += \
 quiet_cmd_hdrtest = HDRTEST $(patsubst %.hdrtest,%.h,$@)
       cmd_hdrtest = \
 		$(CC) $(c_flags) -fsyntax-only -x c /dev/null -include $< -include $<; \
-		PYTHONDONTWRITEBYTECODE=1 $(KERNELDOC) -none $(if $(CONFIG_WERROR)$(CONFIG_DRM_WERROR),-Werror) $<; \
+		PYTHONDONTWRITEBYTECODE=1 $(PYTHON3) $(KERNELDOC) -none $(if $(CONFIG_WERROR)$(CONFIG_DRM_WERROR),-Werror) $<; \
 		touch $@
 
 $(obj)/%.hdrtest: $(src)/%.h FORCE

include/linux/compiler_types.h

@@ -250,10 +250,9 @@ struct ftrace_likely_data {
 /*
  * GCC does not warn about unused static inline functions for -Wunused-function.
  * Suppress the warning in clang as well by using __maybe_unused, but enable it
- * for W=1 build. This will allow clang to find unused functions. Remove the
+ * for W=2 build. This will allow clang to find unused functions.
- * __inline_maybe_unused entirely after fixing most of -Wunused-function warnings.
  */
-#ifdef KBUILD_EXTRA_WARN1
+#ifdef KBUILD_EXTRA_WARN2
 #define __inline_maybe_unused
 #else
 #define __inline_maybe_unused __maybe_unused

scripts/Makefile.build

@@ -167,7 +167,7 @@ else ifeq ($(KBUILD_CHECKSRC),2)
 endif
 
 ifneq ($(KBUILD_EXTRA_WARN),)
-  cmd_checkdoc = PYTHONDONTWRITEBYTECODE=1 $(KERNELDOC) -none $(KDOCFLAGS) \
+  cmd_checkdoc = PYTHONDONTWRITEBYTECODE=1 $(PYTHON3) $(KERNELDOC) -none $(KDOCFLAGS) \
         $(if $(findstring 2, $(KBUILD_EXTRA_WARN)), -Wall) \
         $<
 endif

scripts/Makefile.vmlinux

@@ -102,11 +102,24 @@ vmlinux: vmlinux.unstripped FORCE
 # modules.builtin.modinfo
 # ---------------------------------------------------------------------------
 
+# .modinfo in vmlinux.unstripped is aligned to 8 bytes for compatibility with
+# tools that expect vmlinux to have sufficiently aligned sections but the
+# additional bytes used for padding .modinfo to satisfy this requirement break
+# certain versions of kmod with
+#
+#   depmod: ERROR: kmod_builtin_iter_next: unexpected string without modname prefix
+#
+# Strip the trailing padding bytes after extracting .modinfo to comply with
+# what kmod expects to parse.
+quiet_cmd_modules_builtin_modinfo = GEN     $@
+      cmd_modules_builtin_modinfo = $(cmd_objcopy); \
+                                    sed -i 's/\x00\+$$/\x00/g' $@
+
 OBJCOPYFLAGS_modules.builtin.modinfo := -j .modinfo -O binary
 
 targets += modules.builtin.modinfo
 modules.builtin.modinfo: vmlinux.unstripped FORCE
-	$(call if_changed,objcopy)
+	$(call if_changed,modules_builtin_modinfo)
 
 # modules.builtin
 # ---------------------------------------------------------------------------