[PATCH v2] zlib: Mark get_unaligned16() as __maybe_unused

[PATCH v2] zlib: Mark get_unaligned16() as __maybe_unused

[Matthias Kaehlcke]

The function is not used with all configurations. Adding the attribute
fixes the following warning when building with clang and
CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y:

lib/zlib_inflate/inffast.c:31:1: error: unused function 'get_unaligned16'
    [-Werror,-Wunused-function]
get_unaligned16(const unsigned short *p)

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
Changes in v2:
- explicitly include <linux/compiler.h> where __maybe_unused is defined

 lib/zlib_inflate/inffast.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
index 2c13ecc5bb2c..bae26afdc565 100644
--- a/lib/zlib_inflate/inffast.c
+++ b/lib/zlib_inflate/inffast.c
@@ -3,6 +3,7 @@
  * For conditions of distribution and use, see copyright notice in zlib.h
  */
 
+#include <linux/compiler.h>
 #include <linux/zutil.h>
 #include "inftrees.h"
 #include "inflate.h"
@@ -27,7 +28,7 @@ union uu {
 };
 
 /* Endian independed version */
-static inline unsigned short
+static inline unsigned short __maybe_unused
 get_unaligned16(const unsigned short *p)
 {
 	union uu  mm;
-- 
2.13.0.303.g4ebf302169-goog

Re: [PATCH v2] zlib: Mark get_unaligned16() as __maybe_unused

[kbuild test robot]

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Hi Matthias,

[auto build test ERROR on linus/master]
[also build test ERROR on v4.12-rc2 next-20170522]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Matthias-Kaehlcke/zlib-Mark-get_unaligned16-as-__maybe_unused/20170522-112401
config: powerpc-maple_defconfig (attached as .config)
compiler: powerpc64-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=powerpc 

All errors (new ones prefixed by >>):

>> arch/powerpc/boot/inffast.c:6:22: fatal error: compiler.h: No such file or directory
    #include "compiler.h"
                         ^
   compilation terminated.
--
   In file included from ./arch/powerpc/boot/decompress_inflate.c:10:0,
                    from arch/powerpc/boot/decompress.c:37:
>> ./arch/powerpc/boot/inffast.c:6:22: fatal error: compiler.h: No such file or directory
    #include "compiler.h"
                         ^
   compilation terminated.

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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Re: [PATCH v2] zlib: Mark get_unaligned16() as __maybe_unused

[Matthias Kaehlcke]

El Mon, May 22, 2017 at 04:57:30PM +0800 kbuild test robot ha dit:

> Hi Matthias,
> 
> [auto build test ERROR on linus/master]
> [also build test ERROR on v4.12-rc2 next-20170522]
> [if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
> 
> url:    https://github.com/0day-ci/linux/commits/Matthias-Kaehlcke/zlib-Mark-get_unaligned16-as-__maybe_unused/20170522-112401
> config: powerpc-maple_defconfig (attached as .config)
> compiler: powerpc64-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
> reproduce:
>         wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # save the attached .config to linux build tree
>         make.cross ARCH=powerpc 
> 
> All errors (new ones prefixed by >>):
> 
> >> arch/powerpc/boot/inffast.c:6:22: fatal error: compiler.h: No such file or directory
>     #include "compiler.h"
>                          ^
>    compilation terminated.

I was convinced I build tested this, but I can reproduce the error. I
guess we have to use the bare __attribute__((unused)) :/