[PATCH v2 01/10] ARM: fix duplicate extern declarations

From: Safocl Stollmannovic

Date: Thu Nov 12 2026 - 20:29:46 EST


Compiling a kernel module with a C++ compiler results in a "duplicate
extern specifier" error.
This occurs because the code contains `extern asmlinkage`, and `asmlinkage`
expands to `extern C` when processed by a C++ compiler.
Since the code already contains sections that respond to a C++ compiler,
I believe it is a perfectly valid approach to gradually move toward a state
where kernel modules can be compiled by a C++ compiler without any issues.
The `extern` specifier must be removed.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=222257

Signed-off-by: Safocl Stollmannovic <safocl88@xxxxxxxxx>
---
arch/arm/include/asm/bug.h | 2 +-
arch/arm/include/asm/opcodes.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/bug.h b/arch/arm/include/asm/bug.h
index ba8d9d7d2..985857d65 100644
--- a/arch/arm/include/asm/bug.h
+++ b/arch/arm/include/asm/bug.h
@@ -82,7 +82,7 @@ void hook_ifault_code(int nr, int (*fn)(unsigned long, unsigned int,
struct pt_regs *),
int sig, int code, const char *name);

-extern asmlinkage void c_backtrace(unsigned long fp, int pmode,
+asmlinkage void c_backtrace(unsigned long fp, int pmode,
const char *loglvl);

struct mm_struct;
diff --git a/arch/arm/include/asm/opcodes.h b/arch/arm/include/asm/opcodes.h
index 38e3eabff..afa29833f 100644
--- a/arch/arm/include/asm/opcodes.h
+++ b/arch/arm/include/asm/opcodes.h
@@ -8,7 +8,7 @@

#ifndef __ASSEMBLY__
#include <linux/linkage.h>
-extern asmlinkage unsigned int arm_check_condition(u32 opcode, u32 psr);
+asmlinkage unsigned int arm_check_condition(u32 opcode, u32 psr);
#endif

#define ARM_OPCODE_CONDTEST_FAIL 0
--
2.56.1