linux-kernel - [PATCH] zlib: Put get_unaligned16() inside #ifdef block

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Date:   Mon, 22 May 2017 14:13:26 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Matthias Kaehlcke <mka@...omium.org>
Subject: [PATCH] zlib: Put get_unaligned16() inside #ifdef block

The function is not used when CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y.
Adding the #ifdef fixes the following warning when building with clang:

lib/zlib_inflate/inffast.c:31:1: error: unused function 'get_unaligned16'
    [-Werror,-Wunused-function]

Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
---
Note: Usually we would use the __maybe_unused attribute to silence the
warning. Since this code is used in the kernel decompression stub rather
than in the kernel itself we can't include <linux/compiler.h> with the
definition of __maybe_unused (it would be possible for some platforms,
however for powerpc the build fails with a compiler error). We could
redefine __maybe_unused or use the raw __attribute__((unused)), but
using the #ifdef is a simpler solution.

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

diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
index 2c13ecc5bb2c..af2fd95e35e9 100644
--- a/lib/zlib_inflate/inffast.c
+++ b/lib/zlib_inflate/inffast.c
@@ -26,6 +26,7 @@ union uu {
 	unsigned char b[2];
 };
 
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 /* Endian independed version */
 static inline unsigned short
 get_unaligned16(const unsigned short *p)
@@ -37,6 +38,7 @@ get_unaligned16(const unsigned short *p)
 	mm.b[1] = b[1];
 	return mm.us;
 }
+#endif
 
 #ifdef POSTINC
 #  define OFF 0
-- 
2.13.0.303.g4ebf302169-goog