linux-kernel - [PATCH 2/5] [RESEND] x86: avoid unneeded __div64

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Date:   Tue, 25 Jul 2023 15:48:34 +0200
From:   Arnd Bergmann <arnd@...nel.org>
To:     linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     Arnd Bergmann <arnd@...db.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH 2/5] [RESEND] x86: avoid unneeded __div64_32 function definition

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

The __div64_32() function is provided for 32-bit architectures that
don't have a custom do_div() implementation. x86_32 has one, and
does not use the header file that declares the function prototype,
so the definition causes a W=1 warning:

lib/math/div64.c:31:32: error: no previous prototype for '__div64_32' [-Werror=missing-prototypes]

Define an empty macro to prevent the function definition from getting
built, which avoids the warning and saves a little .text space.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 arch/x86/include/asm/div64.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/include/asm/div64.h b/arch/x86/include/asm/div64.h
index b8f1dc0761e4b..9826d5fc12e34 100644
--- a/arch/x86/include/asm/div64.h
+++ b/arch/x86/include/asm/div64.h
@@ -71,6 +71,8 @@ static inline u64 mul_u32_u32(u32 a, u32 b)
 }
 #define mul_u32_u32 mul_u32_u32
 
+#define __div64_32 /* not needed */
+
 #else
 # include <asm-generic/div64.h>
 
-- 
2.39.2