From 6e8d666e925333c55378e8d5540a8a9ee0eea9c5 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 27 Jul 2016 13:17:41 -0700 Subject: [PATCH] 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: Linus Torvalds --- Makefile | 7 ++++--- arch/arc/Makefile | 4 +--- scripts/Makefile.ubsan | 4 ---- 3 files changed, 5 insertions(+), 10 deletions(-) diff --git a/Makefile b/Makefile index 776b6a3c40f1..d384848478b9 100644 --- a/Makefile +++ b/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 diff --git a/arch/arc/Makefile b/arch/arc/Makefile index 85814e74677d..601ed173080b 100644 --- a/arch/arc/Makefile +++ b/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 diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan index 77ce538268b5..8ab68679cfb5 100644 --- a/scripts/Makefile.ubsan +++ b/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 -- 2.39.5