linux-kernel - [PATCH 4.4 20/73] gcov: disable -Wmaybe-uninitialized warning

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Date:   Wed, 28 Sep 2016 11:04:50 +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, Arnd Bergmann <arnd@...db.de>,
        Peter Oberparleiter <oberpar@...ux.vnet.ibm.com>,
        Michal Marek <mmarek@...e.com>
Subject: [PATCH 4.4 20/73] gcov: disable -Wmaybe-uninitialized warning

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

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

From: Arnd Bergmann <arnd@...db.de>

commit e72e2dfe7c16ffbfbabf9cb24adc6d9f93a4fe37 upstream.

When gcov profiling is enabled, we see a lot of spurious warnings about
possibly uninitialized variables being used:

arch/arm/mm/dma-mapping.c: In function 'arm_coherent_iommu_map_page':
arch/arm/mm/dma-mapping.c:1085:16: warning: 'start' may be used uninitialized in this function [-Wmaybe-uninitialized]
drivers/clk/st/clk-flexgen.c: In function 'st_of_flexgen_setup':
drivers/clk/st/clk-flexgen.c:323:9: warning: 'num_parents' may be used uninitialized in this function [-Wmaybe-uninitialized]
kernel/cgroup.c: In function 'cgroup_mount':
kernel/cgroup.c:2119:11: warning: 'root' may be used uninitialized in this function [-Wmaybe-uninitialized]

All of these are false positives, so it seems better to just disable
the warnings whenever GCOV is enabled. Most users don't enable GCOV,
and based on a prior patch, it is now also disabled for 'allmodconfig'
builds, so there should be no downsides of doing this.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
Acked-by: Peter Oberparleiter <oberpar@...ux.vnet.ibm.com>
Signed-off-by: Michal Marek <mmarek@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 Makefile |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- 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
+CFLAGS_GCOV	= -fprofile-arcs -ftest-coverage -fno-tree-loop-im -Wno-maybe-uninitialized
 
 
 # Use USERINCLUDE when you must reference the UAPI directories only.