While working on an unrelated patch series, I needed to include
linux/bug.h from linux/instrumented.h, in order to call WARN_ON_ONCE().

Doing so resulted in 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, my new WARN_ON_ONCE()
call 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 just remove that include.

The comment about needing BUGFLAG_TAINT seems to be incorrect as of
commit 19d436268dde ("debug: Add _ONCE() logic to report_bug()"). Also,
there's a comment in linux/kernel.h which strongly discourages use of
that header.

Compile-tested only.

Acked-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
---
 arch/parisc/include/asm/bug.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/parisc/include/asm/bug.h b/arch/parisc/include/asm/bug.h
index 833555f74ffa..dbf65623c513 100644
--- a/arch/parisc/include/asm/bug.h
+++ b/arch/parisc/include/asm/bug.h
@@ -2,8 +2,6 @@
 #ifndef _PARISC_BUG_H
 #define _PARISC_BUG_H
 
-#include <linux/kernel.h>	/* for BUGFLAG_TAINT */
-
 /*
  * Tell the user there is some problem.
  * The offending file and line are encoded in the __bug_table section.
-- 
2.49.1

On 11/10/25 01:44, Finn Thain wrote:
> While working on an unrelated patch series, I needed to include
> linux/bug.h from linux/instrumented.h, in order to call WARN_ON_ONCE().
> 
> Doing so resulted in 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, my new WARN_ON_ONCE()
> call 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 just remove that include.
> 
> The comment about needing BUGFLAG_TAINT seems to be incorrect as of
> commit 19d436268dde ("debug: Add _ONCE() logic to report_bug()"). Also,
> there's a comment in linux/kernel.h which strongly discourages use of
> that header.
> 
> Compile-tested only.
> 
> Acked-by: Helge Deller <deller@gmx.de> # parisc
> Signed-off-by: Finn Thain <fthain@linux-m68k.org>
> ---
>   arch/parisc/include/asm/bug.h | 2 --
>   1 file changed, 2 deletions(-)

applied to parisc for-next git tree.

Thanks!
Helge