Commit 6e8d666e authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 468fc7ed

Makefile

+4 −3
Original line number Diff line number Diff line
@@ -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

+1 −3
Original line number Diff line number Diff line
@@ -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

+0 −4
Original line number Diff line number Diff line
@@ -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

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