linux-kernel - [PATCH] arm64/mm: fix variable 'tag' set but not used

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Date:   Wed, 31 Jul 2019 16:38:18 -0400
From:   Qian Cai <cai@....pw>
To:     catalin.marinas@....com, will@...nel.org
Cc:     andreyknvl@...gle.com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Qian Cai <cai@....pw>
Subject: [PATCH] arm64/mm: fix variable 'tag' set but not used

When CONFIG_KASAN_SW_TAGS=n, set_tag() is compiled away. GCC throws a
warning,

mm/kasan/common.c: In function '__kasan_kmalloc':
mm/kasan/common.c:464:5: warning: variable 'tag' set but not used
[-Wunused-but-set-variable]
  u8 tag = 0xff;
     ^~~

Fix it by making __tag_set() a static inline function.

Signed-off-by: Qian Cai <cai@....pw>
---
 arch/arm64/include/asm/memory.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index b7ba75809751..9645b1340afe 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -210,7 +210,11 @@ static inline unsigned long kaslr_offset(void)
 #define __tag_reset(addr)	untagged_addr(addr)
 #define __tag_get(addr)		(__u8)((u64)(addr) >> 56)
 #else
-#define __tag_set(addr, tag)	(addr)
+static inline const void *__tag_set(const void *addr, u8 tag)
+{
+	return addr;
+}
+
 #define __tag_reset(addr)	(addr)
 #define __tag_get(addr)		0
 #endif
-- 
1.8.3.1