[4.2.y-ckt stable] Patch "kbuild: move -Wunused-const-variable to W=1 warning level" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    kbuild: move -Wunused-const-variable to W=1 warning level

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt12.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From bc318f637df9cf9607b335c569c9afdb4b18f375 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd at arndb.de>
Date: Tue, 10 May 2016 23:30:01 +0200
Subject: kbuild: move -Wunused-const-variable to W=1 warning level

commit c9c6837d39311b0cc14cdbe7c18e815ab44aefb1 upstream.

gcc-6 started warning by default about variables that are not
used anywhere and that are marked 'const', generating many
false positives in an allmodconfig build, e.g.:

arch/arm/mach-davinci/board-da830-evm.c:282:20: warning: 'da830_evm_emif25_pins' defined but not used [-Wunused-const-variable=]
arch/arm/plat-omap/dmtimer.c:958:34: warning: 'omap_timer_match' defined but not used [-Wunused-const-variable=]
drivers/bluetooth/hci_bcm.c:625:39: warning: 'acpi_bcm_default_gpios' defined but not used [-Wunused-const-variable=]
drivers/char/hw_random/omap-rng.c:92:18: warning: 'reg_map_omap4' defined but not used [-Wunused-const-variable=]
drivers/devfreq/exynos/exynos5_bus.c:381:32: warning: 'exynos5_busfreq_int_pm' defined but not used [-Wunused-const-variable=]
drivers/dma/mv_xor.c:1139:34: warning: 'mv_xor_dt_ids' defined but not used [-Wunused-const-variable=]

This is similar to the existing -Wunused-but-set-variable warning
that was added in an earlier release and that we disable by default
now and only enable when W=1 is set, so it makes sense to do
the same here. Once we have eliminated the majority of the
warnings for both, we can put them back into the default list.

We probably want this in backport kernels as well, to allow building
them with gcc-6 without introducing extra warnings.

Signed-off-by: Arnd Bergmann <arnd at arndb.de>
Acked-by: Olof Johansson <olof at lixom.net>
Acked-by: Lee Jones <lee.jones at linaro.org>
Signed-off-by: Michal Marek <mmarek at suse.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 Makefile                   | 5 +++--
 scripts/Makefile.extrawarn | 1 +
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 70e04ba..6a1001b 100644
--- a/Makefile
+++ b/Makefile
@@ -688,9 +688,10 @@ KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
 KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
 else

-# This warning generated too much noise in a regular build.
-# Use make W=1 to enable this warning (see scripts/Makefile.build)
+# These warnings generated too much noise in a regular build.
+# Use make W=1 to enable them (see scripts/Makefile.build)
 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
 endif

 ifdef CONFIG_FRAME_POINTER
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 0f8ba77..7339c39 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -24,6 +24,7 @@ warning-1 += $(call cc-option, -Wmissing-prototypes)
 warning-1 += -Wold-style-definition
 warning-1 += $(call cc-option, -Wmissing-include-dirs)
 warning-1 += $(call cc-option, -Wunused-but-set-variable)
+warning-1 += $(call cc-option, -Wunused-const-variable)
 warning-1 += $(call cc-disable-warning, missing-field-initializers)
 warning-1 += $(call cc-disable-warning, sign-compare)

--
2.7.4