Re: [RFC v4 2/5] parisc: Drop linux/kernel.h include from asm/bug.h header

[Helge Deller <deller@gmx.de>]

On 10/21/25 00:28, Finn Thain wrote:
> This patch series will add WARN_ON_ONCE() calls to the header file
> linux/instrumented.h. That requires including linux/bug.h,
> but doing so causes the following compiler error on parisc:
> 
> In file included from ./include/linux/atomic/atomic-instrumented.h:17,
>                   from ./include/linux/atomic.h:82,
>                   from ./arch/parisc/include/asm/bitops.h:13,
>                   from ./include/linux/bitops.h:67,
>                   from ./include/linux/kernel.h:23,
>                   from ./arch/parisc/include/asm/bug.h:5,
>                   from ./include/linux/bug.h:5,
>                   from ./include/linux/page-flags.h:10,
>                   from kernel/bounds.c:10:
> ./include/linux/instrumented.h: In function 'instrument_atomic_alignment_check':
> ./include/linux/instrumented.h:69:9: error: implicit declaration of function 'WARN_ON_ONCE' [-Werror=implicit-function-declaration]
>     69 |         WARN_ON_ONCE((unsigned long)v & (size - 1));
>        |         ^~~~~~~~~~~~
> cc1: some warnings being treated as errors
> make[3]: *** [scripts/Makefile.build:182: kernel/bounds.s] Error 1
> 
> The problem is, asm/bug.h indirectly includes atomic-instrumented.h,
> which means a new cycle appeared in the graph of #includes. And because
> some headers in the cycle can't see all definitions, WARN_ON_ONCE()
> appears to be an undeclared function.
> 
> This only happens on parisc and it's easy to fix. In the error
> message above, linux/kernel.h is included by asm/bug.h. But it's no
> longer needed there, so remove it.
> 
> The comment about needing BUGFLAG_TAINT seems to be incorrect as of
> commit 19d436268dde ("debug: Add _ONCE() logic to report_bug()"). Also,
> a comment in linux/kernel.h strongly discourages its use here.
> 
> Compile-tested only.
> ---
>   arch/parisc/include/asm/bug.h | 2 --
>   1 file changed, 2 deletions(-)

Acked-by: Helge Deller <deller@gmx.de> # parisc

Thanks!
Helge