kbuild: consolidate warning flags in scripts/Makefile.extrawarn

Warning options are enabled and disabled in inconsistent ways and
inconsistent locations. Start rearranging those by moving all options
into Makefile.extrawarn.

This should not change any behavior, but makes sure we can group them
in a way that ensures that each warning that got temporarily disabled
is turned back on at an appropriate W=1 level later on.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Makefile

@@ -563,14 +563,6 @@ KBUILD_CFLAGS += -funsigned-char
 KBUILD_CFLAGS += -fno-common
 KBUILD_CFLAGS += -fno-PIE
 KBUILD_CFLAGS += -fno-strict-aliasing
-KBUILD_CFLAGS += -Wall
-KBUILD_CFLAGS += -Wundef
-KBUILD_CFLAGS += -Werror=implicit-function-declaration
-KBUILD_CFLAGS += -Werror=implicit-int
-KBUILD_CFLAGS += -Werror=return-type
-KBUILD_CFLAGS += -Werror=strict-prototypes
-KBUILD_CFLAGS += -Wno-format-security
-KBUILD_CFLAGS += -Wno-trigraphs
 
 KBUILD_CPPFLAGS := -D__KERNEL__
 KBUILD_RUSTFLAGS := $(rust_common_flags) \
@@ -823,10 +815,6 @@ endif # may-sync-config
 endif # need-config
 
 KBUILD_CFLAGS	+= -fno-delete-null-pointer-checks
-KBUILD_CFLAGS	+= $(call cc-disable-warning,frame-address,)
-KBUILD_CFLAGS	+= $(call cc-disable-warning, format-truncation)
-KBUILD_CFLAGS	+= $(call cc-disable-warning, format-overflow)
-KBUILD_CFLAGS	+= $(call cc-disable-warning, address-of-packed-member)
 
 ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
 KBUILD_CFLAGS += -O2
@@ -857,40 +845,15 @@ ifdef CONFIG_READABLE_ASM
 KBUILD_CFLAGS += -fno-reorder-blocks -fno-ipa-cp-clone -fno-partial-inlining
 endif
 
-ifneq ($(CONFIG_FRAME_WARN),0)
-KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_FRAME_WARN)
-endif
-
 stackp-flags-y                                    := -fno-stack-protector
 stackp-flags-$(CONFIG_STACKPROTECTOR)             := -fstack-protector
 stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG)      := -fstack-protector-strong
 
 KBUILD_CFLAGS += $(stackp-flags-y)
 
-KBUILD_CPPFLAGS-$(CONFIG_WERROR) += -Werror
-KBUILD_CPPFLAGS += $(KBUILD_CPPFLAGS-y)
-KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds
-
 KBUILD_RUSTFLAGS-$(CONFIG_WERROR) += -Dwarnings
 KBUILD_RUSTFLAGS += $(KBUILD_RUSTFLAGS-y)
 
-ifdef CONFIG_CC_IS_CLANG
-# The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable.
-KBUILD_CFLAGS += -Wno-gnu
-else
-
-# gcc inanely warns about local variables called 'main'
-KBUILD_CFLAGS += -Wno-main
-endif
-
-# These warnings generated too much noise in a regular build.
-# Use make W=1 to enable them (see scripts/Makefile.extrawarn)
-KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
-KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
-
-# These result in bogus false positives
-KBUILD_CFLAGS += $(call cc-disable-warning, dangling-pointer)
-
 ifdef CONFIG_FRAME_POINTER
 KBUILD_CFLAGS	+= -fno-omit-frame-pointer -fno-optimize-sibling-calls
 KBUILD_RUSTFLAGS += -Cforce-frame-pointers=y
@@ -1025,51 +988,12 @@ endif
 # arch Makefile may override CC so keep this after arch Makefile is included
 NOSTDINC_FLAGS += -nostdinc
 
-# Variable Length Arrays (VLAs) should not be used anywhere in the kernel
-KBUILD_CFLAGS += -Wvla
-
-# disable pointer signed / unsigned warnings in gcc 4.0
-KBUILD_CFLAGS += -Wno-pointer-sign
-
-# In order to make sure new function cast mismatches are not introduced
-# in the kernel (to avoid tripping CFI checking), the kernel should be
-# globally built with -Wcast-function-type.
-KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type)
-
 # To gain proper coverage for CONFIG_UBSAN_BOUNDS and CONFIG_FORTIFY_SOURCE,
 # the kernel uses only C99 flexible arrays for dynamically sized trailing
 # arrays. Enforce this for everything that may examine structure sizes and
 # perform bounds checking.
 KBUILD_CFLAGS += $(call cc-option, -fstrict-flex-arrays=3)
 
-# disable stringop warnings in gcc 8+
-KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
-
-# We'll want to enable this eventually, but it's not going away for 5.7 at least
-KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow)
-
-# Another good warning that we'll want to enable eventually
-KBUILD_CFLAGS += $(call cc-disable-warning, restrict)
-
-# Enabled with W=2, disabled by default as noisy
-ifdef CONFIG_CC_IS_GCC
-KBUILD_CFLAGS += -Wno-maybe-uninitialized
-endif
-
-# The allocators already balk at large sizes, so silence the compiler
-# warnings for bounds checks involving those possible values. While
-# -Wno-alloc-size-larger-than would normally be used here, earlier versions
-# of gcc (<9.1) weirdly don't handle the option correctly when _other_
-# warnings are produced (?!). Using -Walloc-size-larger-than=SIZE_MAX
-# doesn't work (as it is documented to), silently resolving to "0" prior to
-# version 9.1 (and producing an error more recently). Numeric values larger
-# than PTRDIFF_MAX also don't work prior to version 9.1, which are silently
-# ignored, continuing to default to PTRDIFF_MAX. So, left with no other
-# choice, we must perform a versioned check to disable this warning.
-# https://lore.kernel.org/lkml/20210824115859.187f272f@canb.auug.org.au
-KBUILD_CFLAGS-$(call gcc-min-version, 90100) += -Wno-alloc-size-larger-than
-KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
-
 # disable invalid "can't wrap" optimizations for signed / pointers
 KBUILD_CFLAGS	+= -fno-strict-overflow
 
@@ -1081,18 +1005,6 @@ ifdef CONFIG_CC_IS_GCC
 KBUILD_CFLAGS   += -fconserve-stack
 endif
 
-# Prohibit date/time macros, which would make the build non-deterministic
-KBUILD_CFLAGS   += -Werror=date-time
-
-# enforce correct pointer usage
-KBUILD_CFLAGS   += $(call cc-option,-Werror=incompatible-pointer-types)
-
-# Require designated initializers for all marked structures
-KBUILD_CFLAGS   += $(call cc-option,-Werror=designated-init)
-
-# Warn if there is an enum types mismatch
-KBUILD_CFLAGS	+= $(call cc-option,-Wenum-conversion)
-
 # change __FILE__ to the relative path from the srctree
 KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
 

scripts/Makefile.extrawarn

@@ -6,6 +6,96 @@
 # They are independent, and can be combined like W=12 or W=123e.
 # ==========================================================================
 
+# Default set of warnings, always enabled
+KBUILD_CFLAGS += -Wall
+KBUILD_CFLAGS += -Wundef
+KBUILD_CFLAGS += -Werror=implicit-function-declaration
+KBUILD_CFLAGS += -Werror=implicit-int
+KBUILD_CFLAGS += -Werror=return-type
+KBUILD_CFLAGS += -Werror=strict-prototypes
+KBUILD_CFLAGS += -Wno-format-security
+KBUILD_CFLAGS += -Wno-trigraphs
+KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
+KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
+KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow)
+KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
+
+ifneq ($(CONFIG_FRAME_WARN),0)
+KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_FRAME_WARN)
+endif
+
+KBUILD_CPPFLAGS-$(CONFIG_WERROR) += -Werror
+KBUILD_CPPFLAGS += $(KBUILD_CPPFLAGS-y)
+KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds
+
+ifdef CONFIG_CC_IS_CLANG
+# The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable.
+KBUILD_CFLAGS += -Wno-gnu
+else
+
+# gcc inanely warns about local variables called 'main'
+KBUILD_CFLAGS += -Wno-main
+endif
+
+# These warnings generated too much noise in a regular build.
+# Use make W=1 to enable them (see scripts/Makefile.extrawarn)
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
+
+# These result in bogus false positives
+KBUILD_CFLAGS += $(call cc-disable-warning, dangling-pointer)
+
+# Variable Length Arrays (VLAs) should not be used anywhere in the kernel
+KBUILD_CFLAGS += -Wvla
+
+# disable pointer signed / unsigned warnings in gcc 4.0
+KBUILD_CFLAGS += -Wno-pointer-sign
+
+# In order to make sure new function cast mismatches are not introduced
+# in the kernel (to avoid tripping CFI checking), the kernel should be
+# globally built with -Wcast-function-type.
+KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type)
+
+# disable stringop warnings in gcc 8+
+KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
+
+# We'll want to enable this eventually, but it's not going away for 5.7 at least
+KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow)
+
+# Another good warning that we'll want to enable eventually
+KBUILD_CFLAGS += $(call cc-disable-warning, restrict)
+
+# Enabled with W=2, disabled by default as noisy
+ifdef CONFIG_CC_IS_GCC
+KBUILD_CFLAGS += -Wno-maybe-uninitialized
+endif
+
+# The allocators already balk at large sizes, so silence the compiler
+# warnings for bounds checks involving those possible values. While
+# -Wno-alloc-size-larger-than would normally be used here, earlier versions
+# of gcc (<9.1) weirdly don't handle the option correctly when _other_
+# warnings are produced (?!). Using -Walloc-size-larger-than=SIZE_MAX
+# doesn't work (as it is documented to), silently resolving to "0" prior to
+# version 9.1 (and producing an error more recently). Numeric values larger
+# than PTRDIFF_MAX also don't work prior to version 9.1, which are silently
+# ignored, continuing to default to PTRDIFF_MAX. So, left with no other
+# choice, we must perform a versioned check to disable this warning.
+# https://lore.kernel.org/lkml/20210824115859.187f272f@canb.auug.org.au
+KBUILD_CFLAGS-$(call gcc-min-version, 90100) += -Wno-alloc-size-larger-than
+KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
+
+# Prohibit date/time macros, which would make the build non-deterministic
+KBUILD_CFLAGS += -Werror=date-time
+
+# enforce correct pointer usage
+KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
+
+# Require designated initializers for all marked structures
+KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
+
+# Warn if there is an enum types mismatch
+KBUILD_CFLAGS += $(call cc-option,-Wenum-conversion)
+
 KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
 
 # backward compatibility