kbuild: consolidate extra warnings in scripts/Makefile.extrawarn

The warnings are in two places: the top-level Makefile and
scripts/Makefile.extrawarn, and this is a bit confusing. Also,
a number of possibly useful warnings are disabled unconditionally
when they should really be enabled in one of the higher W= levels.

Move all these warning options to Makefile.extrawarn, and
do not disable the useful ones at least when W=2 is set.
These may be revisited in the future and moved to W=1 or the
default set.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

2 files changed, 36 insertions, 41 deletions

diff --git a/Makefile b/Makefile
index 0af7945caa61b..507d9d5fc53ac 100644
--- a/Makefile
+++ b/Makefile
@@ -494,10 +494,9 @@ LINUXINCLUDE    := \
 		$(USERINCLUDE)
 
 KBUILD_AFLAGS   := -D__ASSEMBLY__ -fno-PIE
-KBUILD_CFLAGS   := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \
+KBUILD_CFLAGS   := -Wall -Wundef -Werror=strict-prototypes \
 		   -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE \
 		   -Werror=implicit-function-declaration -Werror=implicit-int \
-		   -Wno-format-security \
 		   -std=gnu89
 KBUILD_CPPFLAGS := -D__KERNEL__
 KBUILD_AFLAGS_KERNEL :=
@@ -729,10 +728,6 @@ endif # may-sync-config
 endif # need-config
 
 KBUILD_CFLAGS	+= $(call cc-option,-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
@@ -776,17 +771,12 @@ KBUILD_CFLAGS += -Wno-gnu
 KBUILD_CFLAGS += -mno-global-merge
 else
 
-# These warnings generated too much noise in a regular build.
-# Use make W=1 to enable them (see scripts/Makefile.extrawarn)
-KBUILD_CFLAGS += -Wno-unused-but-set-variable
-
 # Warn about unmarked fall-throughs in switch statement.
 # Disabled for clang while comment to attribute conversion happens and
 # https://github.com/ClangBuiltLinux/linux/issues/636 is discussed.
 KBUILD_CFLAGS += $(call cc-option,-Wimplicit-fallthrough,)
 endif
 
-KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
 ifdef CONFIG_FRAME_POINTER
 KBUILD_CFLAGS	+= -fno-omit-frame-pointer -fno-optimize-sibling-calls
 else
@@ -906,23 +896,6 @@ KBUILD_CFLAGS += -Wdeclaration-after-statement
 # 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
-
-# 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, zero-length-bounds)
-KBUILD_CFLAGS += $(call cc-disable-warning, array-bounds)
-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
-KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized)
-
 # disable invalid "can't wrap" optimizations for signed / pointers
 KBUILD_CFLAGS	+= -fno-strict-overflow
 
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 95e4cdb94fe9f..17c902aa5c886 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -6,7 +6,6 @@
 # They are independent, and can be combined like W=12 or W=123.
 # ==========================================================================
 
-KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
 
 # backward compatibility
 KBUILD_EXTRA_WARN ?= $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)
@@ -22,21 +21,12 @@ export KBUILD_EXTRA_WARN
 #
 ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
 
-KBUILD_CFLAGS += -Wextra -Wunused -Wno-unused-parameter
+KBUILD_CFLAGS += -Wextra -Wunused
 KBUILD_CFLAGS += -Wmissing-declarations
 KBUILD_CFLAGS += -Wmissing-format-attribute
 KBUILD_CFLAGS += -Wmissing-prototypes
 KBUILD_CFLAGS += -Wold-style-definition
 KBUILD_CFLAGS += -Wmissing-include-dirs
-KBUILD_CFLAGS += $(call cc-option, -Wunused-but-set-variable)
-KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable)
-KBUILD_CFLAGS += $(call cc-option, -Wpacked-not-aligned)
-KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation)
-# The following turn off the warnings enabled by -Wextra
-KBUILD_CFLAGS += -Wno-missing-field-initializers
-KBUILD_CFLAGS += -Wno-sign-compare
-KBUILD_CFLAGS += -Wno-type-limits
-
 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
 
 else
@@ -51,10 +41,18 @@ KBUILD_CFLAGS += -Wno-sign-compare
 KBUILD_CFLAGS += -Wno-format-zero-length
 KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast)
 KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
+else
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
 endif
 
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
+KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
+KBUILD_CFLAGS += -Wno-empty-body
+KBUILD_CLFAGS += -Wno-trigraphs
+
 endif
 
+
 #
 # W=2 - warnings which occur quite often but may still be relevant
 #
@@ -65,13 +63,32 @@ KBUILD_CFLAGS += -Wdisabled-optimization
 KBUILD_CFLAGS += -Wnested-externs
 KBUILD_CFLAGS += -Wshadow
 KBUILD_CFLAGS += $(call cc-option, -Wlogical-op)
-KBUILD_CFLAGS += -Wmissing-field-initializers
-KBUILD_CFLAGS += -Wtype-limits
 KBUILD_CFLAGS += $(call cc-option, -Wmaybe-uninitialized)
 KBUILD_CFLAGS += $(call cc-option, -Wunused-macros)
 
 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2
 
+else
+
+# We'll want to enable this eventually, but it's not going away for 5.7 at least
+KBUILD_CFLAGS += $(call cc-disable-warning, zero-length-bounds)
+KBUILD_CFLAGS += $(call cc-disable-warning, array-bounds)
+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)
+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)
+KBUILD_CFLAGS += -Wno-format-security
+KBUILD_CFLAGS += -Wno-pointer-sign
+KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized)
+
+# The following turn off the warnings enabled by -Wextra
+KBUILD_CFLAGS += -Wno-missing-field-initializers
+KBUILD_CFLAGS += -Wno-sign-compare
+KBUILD_CFLAGS += -Wno-type-limits
+
 endif
 
 #
@@ -92,4 +109,9 @@ KBUILD_CFLAGS += $(call cc-option, -Wpacked-bitfield-compat)
 
 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3
 
+else
+
+# This is enabled by -Wunused, but generally not helpful
+KBUILD_CFLAGS += -Wno-unused-parameter
+
 endif