Disable "maybe-uninitialized" warning globally

Several build configurations had already disabled this warning because
it generates a lot of false positives.  But some had not, and it was
still enabled for "allmodconfig" builds, for example.

Looking at the warnings produced, every single one I looked at was a
false positive, and the warnings are frequent enough (and big enough)
that they can easily hide real problems that you don't notice in the
noise generated by -Wmaybe-uninitialized.

The warning is good in theory, but this is a classic case of a warning
that causes more problems than the warning can solve.

If gcc gets better at avoiding false positives, we may be able to
re-enable this warning.  But as is, we're better off without it, and I
want to be able to see the *real* warnings.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Makefile

@@ -370,7 +370,7 @@ LDFLAGS_MODULE  =
 CFLAGS_KERNEL	=
 AFLAGS_KERNEL	=
 LDFLAGS_vmlinux =
-CFLAGS_GCOV	= -fprofile-arcs -ftest-coverage -fno-tree-loop-im -Wno-maybe-uninitialized
+CFLAGS_GCOV	= -fprofile-arcs -ftest-coverage -fno-tree-loop-im
 CFLAGS_KCOV	= -fsanitize-coverage=trace-pc
 
 
@@ -619,12 +619,13 @@ ARCH_CFLAGS :=
 include arch/$(SRCARCH)/Makefile
 
 KBUILD_CFLAGS	+= $(call cc-option,-fno-delete-null-pointer-checks,)
+KBUILD_CFLAGS	+= $(call cc-disable-warning,maybe-uninitialized,)
 
 ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
-KBUILD_CFLAGS	+= -Os $(call cc-disable-warning,maybe-uninitialized,)
+KBUILD_CFLAGS	+= -Os
 else
 ifdef CONFIG_PROFILE_ALL_BRANCHES
-KBUILD_CFLAGS	+= -O2 $(call cc-disable-warning,maybe-uninitialized,)
+KBUILD_CFLAGS	+= -O2
 else
 KBUILD_CFLAGS   += -O2
 endif

arch/arc/Makefile

@@ -74,9 +74,7 @@ endif
 ifndef CONFIG_CC_OPTIMIZE_FOR_SIZE
 # Generic build system uses -O2, we want -O3
 # Note: No need to add to cflags-y as that happens anyways
-#
-# Disable the false maybe-uninitialized warings gcc spits out at -O3
-ARCH_CFLAGS += -O3 $(call cc-disable-warning,maybe-uninitialized,)
+ARCH_CFLAGS += -O3
 endif
 
 # small data is default for elf32 tool-chain. If not usable, disable it

scripts/Makefile.ubsan

@@ -14,8 +14,4 @@ ifdef CONFIG_UBSAN
 ifdef CONFIG_UBSAN_ALIGNMENT
       CFLAGS_UBSAN += $(call cc-option, -fsanitize=alignment)
 endif
-
-      # -fsanitize=* options makes GCC less smart than usual and
-      # increase number of 'maybe-uninitialized false-positives
-      CFLAGS_UBSAN += $(call cc-option, -Wno-maybe-uninitialized)
 endif