Re: [PATCH 09/10] sched/preempt: fix duplicate extern declarations

Re: [PATCH 09/10] sched/preempt: fix duplicate extern declarations

[Safocl]

but it contains `asmlinkage`, which includes `extern "C"` when
`__cplusplus` is defined...

Re: [PATCH 09/10] sched/preempt: fix duplicate extern declarations

[Arnd Bergmann]

On Fri, Nov 13, 2026, at 13:02, Safocl wrote:
> but it contains `asmlinkage`, which includes `extern "C"` when
> `__cplusplus` is defined...

That dates back to the (failed) 1993 experiment with having C++ in
the kernel, and before the split of the uapi headers.

     Arnd

Re: [PATCH 09/10] sched/preempt: fix duplicate extern declarations

[Safocl]

Perhaps it’s worth making a change now to ensure some consistency? At
your discretion, you could remove such `extern` specifiers for
functions entirely (along with `asmlinkage`), as they are redundant —
or, alternatively, remove just one of them.

Re: [PATCH 09/10] sched/preempt: fix duplicate extern declarations

[Arnd Bergmann]

On Fri, Nov 13, 2026, at 01:14, Safocl Stollmannovic wrote:
> Compiling a kernel module with a C++ compiler results in a duplicate
> echo ‘extern’ specifier error.
> This occurs because the code contains , and
> expands to  when processed by a C++ compiler.
> The  specifier must be removed.
> https://bugzilla.kernel.org/show_bug.cgi?id=222257

The changelog text makes no sense. We don't support building the
kernel with C++ and this is not a user-visible header.

Leaving out the 'extern' in declarations is just a preference
in coding style, no need to send patches for that.

     Arnd

[PATCH 09/10] sched/preempt: fix duplicate extern declarations

[Safocl Stollmannovic]

Compiling a kernel module with a C++ compiler results in a duplicate
echo ‘extern’ specifier error.
This occurs because the code contains , and
expands to  when processed by a C++ compiler.
The  specifier must be removed.
https://bugzilla.kernel.org/show_bug.cgi?id=222257

Signed-off-by: Safocl Stollmannovic <safocl88@gmail.com>
---
 include/asm-generic/preempt.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/asm-generic/preempt.h b/include/asm-generic/preempt.h
index 1adddeab8..fc0da591d 100644
--- a/include/asm-generic/preempt.h
+++ b/include/asm-generic/preempt.h
@@ -93,8 +93,8 @@ static __always_inline bool should_resched(int preempt_offset)
 }
 
 #ifdef CONFIG_PREEMPTION
-extern asmlinkage void preempt_schedule(void);
-extern asmlinkage void preempt_schedule_notrace(void);
+asmlinkage void preempt_schedule(void);
+asmlinkage void preempt_schedule_notrace(void);
 
 #define __preempt_schedule() preempt_schedule()
 #define __preempt_schedule_notrace() preempt_schedule_notrace()
-- 
2.56.1