4.7-stable review patch. If anyone has any objections, please let me know.
------------------
From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
commit 6e8d666e925333c55378e8d5540a8a9ee0eea9c5 upstream.
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 <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
Makefile | 7 ++++---
arch/arc/Makefile | 4 +---
scripts/Makefile.ubsan | 4 ----
3 files changed, 5 insertions(+), 10 deletions(-)
--- 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
--- 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
--- 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
--
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