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-rw-r--r--Makefile10
-rw-r--r--init/Kconfig17
-rw-r--r--kernel/trace/Kconfig1
3 files changed, 21 insertions, 7 deletions
diff --git a/Makefile b/Makefile
index 7d9032bf47c5..9f52fda4ad0e 100644
--- a/Makefile
+++ b/Makefile
@@ -660,17 +660,13 @@ KBUILD_CFLAGS += $(call cc-disable-warning, int-in-bool-context)
ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
KBUILD_CFLAGS += $(call cc-option,-Oz,-Os)
-KBUILD_CFLAGS += $(call cc-disable-warning,maybe-uninitialized,)
-else
-ifdef CONFIG_PROFILE_ALL_BRANCHES
-KBUILD_CFLAGS += -O2 $(call cc-disable-warning,maybe-uninitialized,)
else
KBUILD_CFLAGS += -O2
endif
-endif
-KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0409, \
- $(call cc-disable-warning,maybe-uninitialized,))
+ifdef CONFIG_CC_DISABLE_WARN_MAYBE_UNINITIALIZED
+KBUILD_CFLAGS += -Wno-maybe-uninitialized
+endif
# Tell gcc to never replace conditional load with a non-conditional one
KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0)
diff --git a/init/Kconfig b/init/Kconfig
index 513fa544a134..ce43083b681d 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -26,6 +26,22 @@ config CLANG_VERSION
config CC_HAS_ASM_GOTO
def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
+config CC_HAS_WARN_MAYBE_UNINITIALIZED
+ def_bool $(cc-option,-Wmaybe-uninitialized)
+ help
+ GCC >= 4.7 supports this option.
+
+config CC_DISABLE_WARN_MAYBE_UNINITIALIZED
+ bool
+ depends on CC_HAS_WARN_MAYBE_UNINITIALIZED
+ default CC_IS_GCC && GCC_VERSION < 40900 # unreliable for GCC < 4.9
+ help
+ GCC's -Wmaybe-uninitialized is not reliable by definition.
+ Lots of false positive warnings are produced in some cases.
+
+ If this option is enabled, -Wno-maybe-uninitialzed is passed
+ to the compiler to suppress maybe-uninitialized warnings.
+
config CONSTRUCTORS
bool
depends on !UML
@@ -1102,6 +1118,7 @@ config CC_OPTIMIZE_FOR_PERFORMANCE
config CC_OPTIMIZE_FOR_SIZE
bool "Optimize for size"
+ imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives
help
Enabling this option will pass "-Os" instead of "-O2" to
your compiler resulting in a smaller kernel.
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index fa8b1fe824f3..8bd1d6d001d7 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -370,6 +370,7 @@ config PROFILE_ANNOTATED_BRANCHES
config PROFILE_ALL_BRANCHES
bool "Profile all if conditionals" if !FORTIFY_SOURCE
select TRACE_BRANCH_PROFILING
+ imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives
help
This tracer profiles all branch conditions. Every if ()
taken in the kernel is recorded whether it hit or miss.