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75b51437a4
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 19d436268d ("debug: Add _ONCE() logic to report_bug()"). Also,
there's a comment in linux/kernel.h which strongly discourages use of
that header.
Acked-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
Signed-off-by: Helge Deller <deller@gmx.de>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
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In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.