linux-kernel - [PATCH 4.4 21/73] Disable "maybe-uninitialized" warning globally

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Message-Id: <20160928090436.048456912@linuxfoundation.org>
Date:   Wed, 28 Sep 2016 11:04:51 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.4 21/73] Disable "maybe-uninitialized" warning globally

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Linus Torvalds <torvalds@...ux-foundation.org>

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@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 Makefile |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/Makefile
+++ b/Makefile
@@ -368,7 +368,7 @@ AFLAGS_MODULE   =
 LDFLAGS_MODULE  =
 CFLAGS_KERNEL	=
 AFLAGS_KERNEL	=
-CFLAGS_GCOV	= -fprofile-arcs -ftest-coverage -fno-tree-loop-im -Wno-maybe-uninitialized
+CFLAGS_GCOV	= -fprofile-arcs -ftest-coverage -fno-tree-loop-im

 # Use USERINCLUDE when you must reference the UAPI directories only.
@@ -616,12 +616,13 @@ 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