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Sat, 14 Nov 2026 08:56:56 -0800 (PST) Received: from SafoStation ([31.40.65.49]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5c1712dad26sm1792051e87.8.2026.11.14.08.56.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 14 Nov 2026 08:56:56 -0800 (PST) From: Safocl Stollmannovic To: Ard Biesheuvel , Ilias Apalodimas , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , "Rafael J. Wysocki" , Pavel Machek , Richard Weinberger , Anton Ivanov , Johannes Berg Cc: linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, linux-pm@vger.kernel.org, linux-um@lists.infradead.org Subject: [PATCH v3 07/14] x86: fix duplicate extern declarations Date: Sat, 14 Nov 2026 20:55:47 +0400 Message-ID: <20261114165612.368785-8-safocl88@gmail.com> X-Mailer: git-send-email 2.56.1 In-Reply-To: <20261114165612.368785-1-safocl88@gmail.com> References: <20261114165612.368785-1-safocl88@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- arch/x86/include/asm/efi.h | 2 +- arch/x86/include/asm/gsseg.h | 2 +- arch/x86/include/asm/preempt.h | 8 ++++---- arch/x86/include/asm/processor.h | 2 +- arch/x86/include/asm/suspend.h | 2 +- arch/x86/um/sys_call_table_32.c | 4 ++-- arch/x86/um/sys_call_table_64.c | 4 ++-- 7 files changed, 12 insertions(+), 12 deletions(-) diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h index be58b7f5c..f5cb179b8 100644 --- a/arch/x86/include/asm/efi.h +++ b/arch/x86/include/asm/efi.h @@ -94,7 +94,7 @@ static inline void efi_fpu_end(void) #else /* !CONFIG_X86_32 */ #define EFI_X86_KERNEL_ALLOC_LIMIT EFI_ALLOC_LIMIT -extern asmlinkage u64 __efi_call(void *fp, ...); +asmlinkage u64 __efi_call(void *fp, ...); extern bool efi_disable_ibt_for_runtime; diff --git a/arch/x86/include/asm/gsseg.h b/arch/x86/include/asm/gsseg.h index ab6a595ce..81ef16081 100644 --- a/arch/x86/include/asm/gsseg.h +++ b/arch/x86/include/asm/gsseg.h @@ -12,7 +12,7 @@ #ifdef CONFIG_X86_64 -extern asmlinkage void asm_load_gs_index(u16 selector); +asmlinkage void asm_load_gs_index(u16 selector); /* Replace with "lkgs %di" once binutils support LKGS instruction */ #define LKGS_DI _ASM_BYTES(0xf2,0x0f,0x00,0xf7) diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h index d16d9c2f7..135695ae3 100644 --- a/arch/x86/include/asm/preempt.h +++ b/arch/x86/include/asm/preempt.h @@ -134,11 +134,11 @@ static __always_inline bool should_resched(int preempt_offset) #ifdef CONFIG_PREEMPTION -extern asmlinkage void preempt_schedule(void); -extern asmlinkage void preempt_schedule_thunk(void); +asmlinkage void preempt_schedule(void); +asmlinkage void preempt_schedule_thunk(void); -extern asmlinkage void preempt_schedule_notrace(void); -extern asmlinkage void preempt_schedule_notrace_thunk(void); +asmlinkage void preempt_schedule_notrace(void); +asmlinkage void preempt_schedule_notrace_thunk(void); #define __preempt_schedule() \ asm volatile ("call preempt_schedule_thunk" : ASM_CALL_CONSTRAINT); diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 77488ff5e..68d7292af 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -455,7 +455,7 @@ static inline unsigned long cpu_kernelmode_gs_base(int cpu) #endif } -extern asmlinkage void entry_SYSCALL32_ignore(void); +asmlinkage void entry_SYSCALL32_ignore(void); /* Save actual FS/GS selectors and bases to current->thread */ void current_save_fsgs(void); diff --git a/arch/x86/include/asm/suspend.h b/arch/x86/include/asm/suspend.h index a892494ca..e29c071b9 100644 --- a/arch/x86/include/asm/suspend.h +++ b/arch/x86/include/asm/suspend.h @@ -11,4 +11,4 @@ extern unsigned long temp_pgt __visible; extern unsigned long relocated_restore_code __visible; extern int relocate_restore_code(void); /* Defined in hibernate_asm_32/64.S */ -extern asmlinkage __visible int restore_image(void); +asmlinkage __visible int restore_image(void); diff --git a/arch/x86/um/sys_call_table_32.c b/arch/x86/um/sys_call_table_32.c index 51655133e..f79c0138e 100644 --- a/arch/x86/um/sys_call_table_32.c +++ b/arch/x86/um/sys_call_table_32.c @@ -9,7 +9,7 @@ #include #include -extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long, +asmlinkage long sys_ni_syscall(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); @@ -28,7 +28,7 @@ extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long, #define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native) #define __SYSCALL_NORETURN __SYSCALL -#define __SYSCALL(nr, sym) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); +#define __SYSCALL(nr, sym) asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); #include #undef __SYSCALL diff --git a/arch/x86/um/sys_call_table_64.c b/arch/x86/um/sys_call_table_64.c index 943d414f2..555e65e66 100644 --- a/arch/x86/um/sys_call_table_64.c +++ b/arch/x86/um/sys_call_table_64.c @@ -9,7 +9,7 @@ #include #include -extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long, +asmlinkage long sys_ni_syscall(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); @@ -24,7 +24,7 @@ extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long, #define __SYSCALL_NORETURN __SYSCALL -#define __SYSCALL(nr, sym) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); +#define __SYSCALL(nr, sym) asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); #include #undef __SYSCALL -- 2.56.1