License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 15:07:57 +01:00
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# SPDX-License-Identifier: GPL-2.0
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2014-04-14 18:27:10 +09:00
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# ==========================================================================
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# make W=... settings
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#
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2022-04-08 10:46:07 +02:00
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# There are four warning groups enabled by W=1, W=2, W=3, and W=e
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# They are independent, and can be combined like W=12 or W=123e.
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2014-04-14 18:27:10 +09:00
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# ==========================================================================
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2023-08-11 16:03:20 +02:00
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# Default set of warnings, always enabled
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KBUILD_CFLAGS += -Wall
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2025-04-30 15:56:34 -07:00
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KBUILD_CFLAGS += -Wextra
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2023-08-11 16:03:20 +02:00
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KBUILD_CFLAGS += -Wundef
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KBUILD_CFLAGS += -Werror=implicit-function-declaration
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KBUILD_CFLAGS += -Werror=implicit-int
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KBUILD_CFLAGS += -Werror=return-type
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KBUILD_CFLAGS += -Werror=strict-prototypes
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KBUILD_CFLAGS += -Wno-format-security
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KBUILD_CFLAGS += -Wno-trigraphs
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2025-05-27 14:40:30 -07:00
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KBUILD_CFLAGS += $(call cc-option, -Wno-frame-address)
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KBUILD_CFLAGS += $(call cc-option, -Wno-address-of-packed-member)
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Makefile.extrawarn: turn on missing-prototypes globally
Over the years we went from > 1000 of warnings to under 100 earlier this
year, and I sent patches to address all the ones that I saw with compile
testing randcom configs on arm64, arm and x86 kernels. This is a really
useful warning, as it catches real bugs when there are mismatched
prototypes. In particular with kernel control flow integrity enabled,
those are no longer allowed.
I have done extensive testing to ensure that there are no new build errors
or warnings on any configuration of x86, arm and arm64 builds. I also
made sure that at least both the normal defconfig and an allmodconfig
build is clean for arc, csky, loongarch, m68k, microblaze, openrisc,
parisc, powerpc, riscv, s390, and xtensa, with the respective maintainers
doing most of the patches.
At this point, there are five architectures with a number of known
regressions: alpha, nios2, mips, sh and sparc. In the previous version of
this patch, I had turned off the missing prototype warnings for the 15
architectures that still had issues, but since there are only five left, I
think we can leave the rest to the maintainers (Cc'd here) as well.
Link: https://lkml.kernel.org/r/20231123110506.707903-7-arnd@kernel.org
Link: https://lore.kernel.org/lkml/20230810141947.1236730-1-arnd@kernel.org/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com> # RISC-V
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nicolas Schier <nicolas@fjasle.eu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tudor Ambarus <tudor.ambarus@linaro.org>
Cc: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-11-23 12:05:06 +01:00
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KBUILD_CFLAGS += -Wmissing-declarations
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KBUILD_CFLAGS += -Wmissing-prototypes
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2023-08-11 16:03:20 +02:00
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ifneq ($(CONFIG_FRAME_WARN),0)
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KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_FRAME_WARN)
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endif
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KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds
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ifdef CONFIG_CC_IS_CLANG
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# The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable.
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KBUILD_CFLAGS += -Wno-gnu
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2025-01-31 15:55:28 -07:00
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# Clang checks for overflow/truncation with '%p', while GCC does not:
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# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111219
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2025-05-27 14:40:30 -07:00
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KBUILD_CFLAGS += $(call cc-option, -Wno-format-overflow-non-kprintf)
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KBUILD_CFLAGS += $(call cc-option, -Wno-format-truncation-non-kprintf)
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kbuild: Disable -Wdefault-const-init-unsafe
A new on by default warning in clang [1] aims to flags instances where
const variables without static or thread local storage or const members
in aggregate types are not initialized because it can lead to an
indeterminate value. This is quite noisy for the kernel due to
instances originating from header files such as:
drivers/gpu/drm/i915/gt/intel_ring.h:62:2: error: default initialization of an object of type 'typeof (ring->size)' (aka 'const unsigned int') leaves the object uninitialized [-Werror,-Wdefault-const-init-var-unsafe]
62 | typecheck(typeof(ring->size), next);
| ^
include/linux/typecheck.h:10:9: note: expanded from macro 'typecheck'
10 | ({ type __dummy; \
| ^
include/net/ip.h:478:14: error: default initialization of an object of type 'typeof (rt->dst.expires)' (aka 'const unsigned long') leaves the object uninitialized [-Werror,-Wdefault-const-init-var-unsafe]
478 | if (mtu && time_before(jiffies, rt->dst.expires))
| ^
include/linux/jiffies.h:138:26: note: expanded from macro 'time_before'
138 | #define time_before(a,b) time_after(b,a)
| ^
include/linux/jiffies.h:128:3: note: expanded from macro 'time_after'
128 | (typecheck(unsigned long, a) && \
| ^
include/linux/typecheck.h:11:12: note: expanded from macro 'typecheck'
11 | typeof(x) __dummy2; \
| ^
include/linux/list.h:409:27: warning: default initialization of an object of type 'union (unnamed union at include/linux/list.h:409:27)' with const member leaves the object uninitialized [-Wdefault-const-init-field-unsafe]
409 | struct list_head *next = smp_load_acquire(&head->next);
| ^
include/asm-generic/barrier.h:176:29: note: expanded from macro 'smp_load_acquire'
176 | #define smp_load_acquire(p) __smp_load_acquire(p)
| ^
arch/arm64/include/asm/barrier.h:164:59: note: expanded from macro '__smp_load_acquire'
164 | union { __unqual_scalar_typeof(*p) __val; char __c[1]; } __u; \
| ^
include/linux/list.h:409:27: note: member '__val' declared 'const' here
crypto/scatterwalk.c:66:22: error: default initialization of an object of type 'struct scatter_walk' with const member leaves the object uninitialized [-Werror,-Wdefault-const-init-field-unsafe]
66 | struct scatter_walk walk;
| ^
include/crypto/algapi.h:112:15: note: member 'addr' declared 'const' here
112 | void *const addr;
| ^
fs/hugetlbfs/inode.c:733:24: error: default initialization of an object of type 'struct vm_area_struct' with const member leaves the object uninitialized [-Werror,-Wdefault-const-init-field-unsafe]
733 | struct vm_area_struct pseudo_vma;
| ^
include/linux/mm_types.h:803:20: note: member 'vm_flags' declared 'const' here
803 | const vm_flags_t vm_flags;
| ^
Silencing the instances from typecheck.h is difficult because '= {}' is
not available in older but supported compilers and '= {0}' would cause
warnings about a literal 0 being treated as NULL. While it might be
possible to come up with a local hack to silence the warning for
clang-21+, it may not be worth it since -Wuninitialized will still
trigger if an uninitialized const variable is actually used.
In all audited cases of the "field" variant of the warning, the members
are either not used in the particular call path, modified through other
means such as memset() / memcpy() because the containing object is not
const, or are within a union with other non-const members.
Since this warning does not appear to have a high signal to noise ratio,
just disable it.
Cc: stable@vger.kernel.org
Link: https://github.com/llvm/llvm-project/commit/576161cb6069e2c7656a8ef530727a0f4aefff30 [1]
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/CA+G9fYuNjKcxFKS_MKPRuga32XbndkLGcY-PVuoSwzv6VWbY=w@mail.gmail.com/
Reported-by: Marcus Seyfarth <m.seyfarth@gmail.com>
Closes: https://github.com/ClangBuiltLinux/linux/issues/2088
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2025-05-06 14:02:01 -07:00
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# Clang may emit a warning when a const variable, such as the dummy variables
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# in typecheck(), or const member of an aggregate type are not initialized,
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# which can result in unexpected behavior. However, in many audited cases of
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# the "field" variant of the warning, this is intentional because the field is
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# never used within a particular call path, the field is within a union with
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# other non-const members, or the containing object is not const so the field
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# can be modified via memcpy() / memset(). While the variable warning also gets
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# disabled with this same switch, there should not be too much coverage lost
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# because -Wuninitialized will still flag when an uninitialized const variable
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# is used.
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2025-05-27 14:40:30 -07:00
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KBUILD_CFLAGS += $(call cc-option, -Wno-default-const-init-unsafe)
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2023-08-11 16:03:20 +02:00
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else
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# gcc inanely warns about local variables called 'main'
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KBUILD_CFLAGS += -Wno-main
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endif
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# These result in bogus false positives
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2025-05-27 14:40:30 -07:00
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KBUILD_CFLAGS += $(call cc-option, -Wno-dangling-pointer)
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2023-08-11 16:03:20 +02:00
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2025-04-18 14:32:39 -07:00
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# Stack Variable Length Arrays (VLAs) must not be used in the kernel.
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# Function array parameters should, however, be usable, but -Wvla will
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# warn for those. Clang has no way yet to distinguish between the VLA
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# types, so depend on GCC for now to keep stack VLAs out of the tree.
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# https://github.com/llvm/llvm-project/issues/57098
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# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98217
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KBUILD_CFLAGS += $(call cc-option,-Wvla-larger-than=1)
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2023-08-11 16:03:20 +02:00
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# disable pointer signed / unsigned warnings in gcc 4.0
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KBUILD_CFLAGS += -Wno-pointer-sign
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# In order to make sure new function cast mismatches are not introduced
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# in the kernel (to avoid tripping CFI checking), the kernel should be
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# globally built with -Wcast-function-type.
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KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type)
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2025-04-30 15:56:34 -07:00
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# Currently, disable -Wstringop-overflow for GCC 11, globally.
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2025-05-27 14:40:30 -07:00
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KBUILD_CFLAGS-$(CONFIG_CC_NO_STRINGOP_OVERFLOW) += $(call cc-option, -Wno-stringop-overflow)
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2025-04-30 15:56:34 -07:00
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KBUILD_CFLAGS-$(CONFIG_CC_STRINGOP_OVERFLOW) += $(call cc-option, -Wstringop-overflow)
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# Currently, disable -Wunterminated-string-initialization as broken
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2025-05-27 14:40:30 -07:00
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KBUILD_CFLAGS += $(call cc-option, -Wno-unterminated-string-initialization)
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2025-04-30 15:56:34 -07:00
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2023-08-11 16:03:20 +02:00
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# The allocators already balk at large sizes, so silence the compiler
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# warnings for bounds checks involving those possible values. While
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# -Wno-alloc-size-larger-than would normally be used here, earlier versions
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# of gcc (<9.1) weirdly don't handle the option correctly when _other_
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# warnings are produced (?!). Using -Walloc-size-larger-than=SIZE_MAX
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# doesn't work (as it is documented to), silently resolving to "0" prior to
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# version 9.1 (and producing an error more recently). Numeric values larger
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# than PTRDIFF_MAX also don't work prior to version 9.1, which are silently
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# ignored, continuing to default to PTRDIFF_MAX. So, left with no other
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# choice, we must perform a versioned check to disable this warning.
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# https://lore.kernel.org/lkml/20210824115859.187f272f@canb.auug.org.au
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KBUILD_CFLAGS-$(call gcc-min-version, 90100) += -Wno-alloc-size-larger-than
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KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
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# Prohibit date/time macros, which would make the build non-deterministic
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KBUILD_CFLAGS += -Werror=date-time
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# enforce correct pointer usage
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KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
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# Require designated initializers for all marked structures
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KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
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# Warn if there is an enum types mismatch
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KBUILD_CFLAGS += $(call cc-option,-Wenum-conversion)
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2024-04-15 14:20:32 +02:00
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KBUILD_CFLAGS += -Wunused
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kbuild: refactor scripts/Makefile.extrawarn
Instead of the warning-[123] magic, let's accumulate compiler options
to KBUILD_CFLAGS directly as the top Makefile does. I think this makes
it easier to understand what is going on in this file.
This commit slightly changes the behavior, I think all of which are OK.
[1] Currently, cc-option calls are needlessly evaluated. For example,
warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
needs evaluating only when W=3, but it is actually evaluated for
W=1, W=2 as well. With this commit, only relevant cc-option calls
will be evaluated. This is a slight optimization.
[2] Currently, unsupported level like W=4 is checked by:
$(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
This will no longer be checked, but I do not think it is a big
deal.
[3] Currently, 4 Clang warnings (Winitializer-overrides, Wformat,
Wsign-compare, Wformat-zero-length) are shown by any of W=1, W=2,
and W=3. With this commit, they will be warned only by W=1. I
think this is a more correct behavior since each warning belongs
to only one group.
For understanding this commit correctly:
We have 3 warning groups, W=1, W=2, and W=3. You may think W=3 has a
higher level than W=1, but they are actually independent. If you like,
you can combine them like W=13. To enable all the warnings, you can
pass W=123. It is shown by 'make help', but not noticed much. Since we
support W= combination, there should not exist intersection among the
three groups. If we enable Winitializer-overrides for W=1, we do not
need to for W=2 or W=3. This is the reason why I think the change [3]
makes sense.
The documentation says -Winitializer-overrides is enabled by default.
(https://clang.llvm.org/docs/DiagnosticsReference.html#winitializer-overrides)
We negate it by passing -Wno-initializer-overrides for the normal
build, but we do not do that for W=1. This means, W=1 effectively
enables -Winitializer-overrides by the clang's default. The same for
the other three.
Add comments in case people are confused with the code.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
2019-09-01 01:25:54 +09:00
|
|
|
#
|
|
|
|
|
# W=1 - warnings which may be relevant and do not occur too often
|
|
|
|
|
#
|
2019-09-01 01:25:55 +09:00
|
|
|
ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
|
2014-04-14 18:27:10 +09:00
|
|
|
|
kbuild: refactor scripts/Makefile.extrawarn
Instead of the warning-[123] magic, let's accumulate compiler options
to KBUILD_CFLAGS directly as the top Makefile does. I think this makes
it easier to understand what is going on in this file.
This commit slightly changes the behavior, I think all of which are OK.
[1] Currently, cc-option calls are needlessly evaluated. For example,
warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
needs evaluating only when W=3, but it is actually evaluated for
W=1, W=2 as well. With this commit, only relevant cc-option calls
will be evaluated. This is a slight optimization.
[2] Currently, unsupported level like W=4 is checked by:
$(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
This will no longer be checked, but I do not think it is a big
deal.
[3] Currently, 4 Clang warnings (Winitializer-overrides, Wformat,
Wsign-compare, Wformat-zero-length) are shown by any of W=1, W=2,
and W=3. With this commit, they will be warned only by W=1. I
think this is a more correct behavior since each warning belongs
to only one group.
For understanding this commit correctly:
We have 3 warning groups, W=1, W=2, and W=3. You may think W=3 has a
higher level than W=1, but they are actually independent. If you like,
you can combine them like W=13. To enable all the warnings, you can
pass W=123. It is shown by 'make help', but not noticed much. Since we
support W= combination, there should not exist intersection among the
three groups. If we enable Winitializer-overrides for W=1, we do not
need to for W=2 or W=3. This is the reason why I think the change [3]
makes sense.
The documentation says -Winitializer-overrides is enabled by default.
(https://clang.llvm.org/docs/DiagnosticsReference.html#winitializer-overrides)
We negate it by passing -Wno-initializer-overrides for the normal
build, but we do not do that for W=1. This means, W=1 effectively
enables -Winitializer-overrides by the clang's default. The same for
the other three.
Add comments in case people are confused with the code.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
2019-09-01 01:25:54 +09:00
|
|
|
KBUILD_CFLAGS += -Wmissing-format-attribute
|
|
|
|
|
KBUILD_CFLAGS += -Wmissing-include-dirs
|
|
|
|
|
KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable)
|
2014-04-14 18:27:10 +09:00
|
|
|
|
2022-12-06 13:07:31 +09:00
|
|
|
KBUILD_CPPFLAGS += -Wundef
|
kbuild: allow Clang to find unused static inline functions for W=1 build
GCC and Clang have different policy for -Wunused-function; GCC does not
warn unused static inline functions at all whereas Clang does if they
are defined in source files instead of included headers although it has
been suppressed since commit abb2ea7dfd82 ("compiler, clang: suppress
warning for unused static inline functions").
We often miss to delete unused functions where 'static inline' is used
in *.c files since there is no tool to detect them. Unused code remains
until somebody notices. For example, commit 075ddd75680f ("regulator:
core: remove unused rdev_get_supply()").
Let's remove __maybe_unused from the inline macro to allow Clang to
start finding unused static inline functions. For now, we do this only
for W=1 build since it is not a good idea to sprinkle warnings for the
normal build (e.g. 35 warnings for arch/x86/configs/x86_64_defconfig).
My initial attempt was to add -Wno-unused-function for no W= build
(https://lore.kernel.org/patchwork/patch/1120594/)
Nathan Chancellor pointed out that would weaken Clang's checks since
we would no longer get -Wunused-function without W=1. It is true GCC
would catch unused static non-inline functions, but it would weaken
Clang as a standalone compiler, at least.
Hence, here is a counter implementation. The current problem is, W=...
only controls compiler flags, which are globally effective. There is
no way to address only 'static inline' functions.
This commit defines KBUILD_EXTRA_WARN[123] corresponding to W=[123].
When KBUILD_EXTRA_WARN1 is defined, __maybe_unused is omitted from
the 'inline' macro.
The new macro __inline_maybe_unused makes the code a bit uglier, so I
hope we can remove it entirely after fixing most of the warnings.
If you contribute to code clean-up, please run "make CC=clang W=1"
and check -Wunused-function warnings. You will find lots of unused
functions.
Some of them are false-positives because the call-sites are disabled
by #ifdef. I do not like to abuse the inline keyword for suppressing
unused-function warnings because it is intended to be a hint for the
compiler optimization. I prefer #ifdef around the definition, or
__maybe_unused if #ifdef would make the code too ugly.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
2019-09-07 11:52:36 +09:00
|
|
|
KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
|
|
|
|
|
|
2014-07-31 21:08:25 -07:00
|
|
|
else
|
|
|
|
|
|
kbuild: refactor scripts/Makefile.extrawarn
Instead of the warning-[123] magic, let's accumulate compiler options
to KBUILD_CFLAGS directly as the top Makefile does. I think this makes
it easier to understand what is going on in this file.
This commit slightly changes the behavior, I think all of which are OK.
[1] Currently, cc-option calls are needlessly evaluated. For example,
warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
needs evaluating only when W=3, but it is actually evaluated for
W=1, W=2 as well. With this commit, only relevant cc-option calls
will be evaluated. This is a slight optimization.
[2] Currently, unsupported level like W=4 is checked by:
$(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
This will no longer be checked, but I do not think it is a big
deal.
[3] Currently, 4 Clang warnings (Winitializer-overrides, Wformat,
Wsign-compare, Wformat-zero-length) are shown by any of W=1, W=2,
and W=3. With this commit, they will be warned only by W=1. I
think this is a more correct behavior since each warning belongs
to only one group.
For understanding this commit correctly:
We have 3 warning groups, W=1, W=2, and W=3. You may think W=3 has a
higher level than W=1, but they are actually independent. If you like,
you can combine them like W=13. To enable all the warnings, you can
pass W=123. It is shown by 'make help', but not noticed much. Since we
support W= combination, there should not exist intersection among the
three groups. If we enable Winitializer-overrides for W=1, we do not
need to for W=2 or W=3. This is the reason why I think the change [3]
makes sense.
The documentation says -Winitializer-overrides is enabled by default.
(https://clang.llvm.org/docs/DiagnosticsReference.html#winitializer-overrides)
We negate it by passing -Wno-initializer-overrides for the normal
build, but we do not do that for W=1. This means, W=1 effectively
enables -Winitializer-overrides by the clang's default. The same for
the other three.
Add comments in case people are confused with the code.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
2019-09-01 01:25:54 +09:00
|
|
|
# Some diagnostics enabled by default are noisy.
|
|
|
|
|
# Suppress them by using -Wno... except for W=1.
|
2025-05-27 14:40:30 -07:00
|
|
|
KBUILD_CFLAGS += $(call cc-option, -Wno-unused-but-set-variable)
|
|
|
|
|
KBUILD_CFLAGS += $(call cc-option, -Wno-unused-const-variable)
|
|
|
|
|
KBUILD_CFLAGS += $(call cc-option, -Wno-packed-not-aligned)
|
|
|
|
|
KBUILD_CFLAGS += $(call cc-option, -Wno-format-overflow)
|
2024-04-15 14:20:35 +02:00
|
|
|
ifdef CONFIG_CC_IS_GCC
|
2025-05-27 14:40:30 -07:00
|
|
|
KBUILD_CFLAGS += $(call cc-option, -Wno-format-truncation)
|
2024-04-15 14:20:35 +02:00
|
|
|
endif
|
2025-05-27 14:40:30 -07:00
|
|
|
KBUILD_CFLAGS += $(call cc-option, -Wno-stringop-truncation)
|
kbuild: refactor scripts/Makefile.extrawarn
Instead of the warning-[123] magic, let's accumulate compiler options
to KBUILD_CFLAGS directly as the top Makefile does. I think this makes
it easier to understand what is going on in this file.
This commit slightly changes the behavior, I think all of which are OK.
[1] Currently, cc-option calls are needlessly evaluated. For example,
warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
needs evaluating only when W=3, but it is actually evaluated for
W=1, W=2 as well. With this commit, only relevant cc-option calls
will be evaluated. This is a slight optimization.
[2] Currently, unsupported level like W=4 is checked by:
$(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
This will no longer be checked, but I do not think it is a big
deal.
[3] Currently, 4 Clang warnings (Winitializer-overrides, Wformat,
Wsign-compare, Wformat-zero-length) are shown by any of W=1, W=2,
and W=3. With this commit, they will be warned only by W=1. I
think this is a more correct behavior since each warning belongs
to only one group.
For understanding this commit correctly:
We have 3 warning groups, W=1, W=2, and W=3. You may think W=3 has a
higher level than W=1, but they are actually independent. If you like,
you can combine them like W=13. To enable all the warnings, you can
pass W=123. It is shown by 'make help', but not noticed much. Since we
support W= combination, there should not exist intersection among the
three groups. If we enable Winitializer-overrides for W=1, we do not
need to for W=2 or W=3. This is the reason why I think the change [3]
makes sense.
The documentation says -Winitializer-overrides is enabled by default.
(https://clang.llvm.org/docs/DiagnosticsReference.html#winitializer-overrides)
We negate it by passing -Wno-initializer-overrides for the normal
build, but we do not do that for W=1. This means, W=1 effectively
enables -Winitializer-overrides by the clang's default. The same for
the other three.
Add comments in case people are confused with the code.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
2019-09-01 01:25:54 +09:00
|
|
|
|
2024-03-26 15:47:16 +01:00
|
|
|
KBUILD_CFLAGS += -Wno-override-init # alias for -Wno-initializer-overrides in clang
|
|
|
|
|
|
2018-10-30 22:26:33 +09:00
|
|
|
ifdef CONFIG_CC_IS_CLANG
|
2022-09-01 10:59:13 -07:00
|
|
|
# Clang before clang-16 would warn on default argument promotions.
|
2022-09-19 10:08:28 -07:00
|
|
|
ifneq ($(call clang-min-version, 160000),y)
|
2022-09-01 10:59:13 -07:00
|
|
|
# Disable -Wformat
|
Revert "Makefile.extrawarn: re-enable -Wformat for clang"
This reverts commit 258fafcd0683d9ccfa524129d489948ab3ddc24c.
The clang -Wformat warning is terminally broken, and the clang people
can't seem to get their act together.
This test program causes a warning with clang:
#include <stdio.h>
int main(int argc, char **argv)
{
printf("%hhu\n", 'a');
}
resulting in
t.c:5:19: warning: format specifies type 'unsigned char' but the argument has type 'int' [-Wformat]
printf("%hhu\n", 'a');
~~~~ ^~~
%d
and apparently clang people consider that a feature, because they don't
want to face the reality of how either C character constants, C
arithmetic, and C varargs functions work.
The rest of the world just shakes their head at that kind of
incompetence, and turns off -Wformat for clang again.
And no, the "you should use a pointless cast to shut this up" is not a
valid answer. That warning should not exist in the first place, or at
least be optinal with some "-Wformat-me-harder" kind of option.
[ Admittedly, there's also very little reason to *ever* use '%hh[ud]' in
C, but what little reason there is is entirely about 'I want to see
only the low 8 bits of the argument'. So I would suggest nobody ever
use that format in the first place, but if they do, the clang
behavious is simply always wrong. Because '%hhu' takes an 'int'. It's
that simple. ]
Reported-by: Sudip Mukherjee (Codethink) <sudipm.mukherjee@gmail.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-08-11 08:40:01 -07:00
|
|
|
KBUILD_CFLAGS += -Wno-format
|
2022-09-01 10:59:13 -07:00
|
|
|
# Then re-enable flags that were part of the -Wformat group that aren't
|
|
|
|
|
# problematic.
|
|
|
|
|
KBUILD_CFLAGS += -Wformat-extra-args -Wformat-invalid-specifier
|
|
|
|
|
KBUILD_CFLAGS += -Wformat-zero-length -Wnonnull
|
|
|
|
|
# Requires clang-12+.
|
2022-09-19 10:08:28 -07:00
|
|
|
ifeq ($(call clang-min-version, 120000),y)
|
2022-09-01 10:59:13 -07:00
|
|
|
KBUILD_CFLAGS += -Wformat-insufficient-args
|
|
|
|
|
endif
|
|
|
|
|
endif
|
2025-05-27 14:40:30 -07:00
|
|
|
KBUILD_CFLAGS += $(call cc-option, -Wno-pointer-to-enum-cast)
|
2020-03-26 12:41:55 -07:00
|
|
|
KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
|
2025-05-27 14:40:30 -07:00
|
|
|
KBUILD_CFLAGS += $(call cc-option, -Wno-unaligned-access)
|
2024-03-05 15:12:47 -07:00
|
|
|
KBUILD_CFLAGS += -Wno-enum-compare-conditional
|
2014-07-31 21:08:25 -07:00
|
|
|
endif
|
kbuild: refactor scripts/Makefile.extrawarn
Instead of the warning-[123] magic, let's accumulate compiler options
to KBUILD_CFLAGS directly as the top Makefile does. I think this makes
it easier to understand what is going on in this file.
This commit slightly changes the behavior, I think all of which are OK.
[1] Currently, cc-option calls are needlessly evaluated. For example,
warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
needs evaluating only when W=3, but it is actually evaluated for
W=1, W=2 as well. With this commit, only relevant cc-option calls
will be evaluated. This is a slight optimization.
[2] Currently, unsupported level like W=4 is checked by:
$(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
This will no longer be checked, but I do not think it is a big
deal.
[3] Currently, 4 Clang warnings (Winitializer-overrides, Wformat,
Wsign-compare, Wformat-zero-length) are shown by any of W=1, W=2,
and W=3. With this commit, they will be warned only by W=1. I
think this is a more correct behavior since each warning belongs
to only one group.
For understanding this commit correctly:
We have 3 warning groups, W=1, W=2, and W=3. You may think W=3 has a
higher level than W=1, but they are actually independent. If you like,
you can combine them like W=13. To enable all the warnings, you can
pass W=123. It is shown by 'make help', but not noticed much. Since we
support W= combination, there should not exist intersection among the
three groups. If we enable Winitializer-overrides for W=1, we do not
need to for W=2 or W=3. This is the reason why I think the change [3]
makes sense.
The documentation says -Winitializer-overrides is enabled by default.
(https://clang.llvm.org/docs/DiagnosticsReference.html#winitializer-overrides)
We negate it by passing -Wno-initializer-overrides for the normal
build, but we do not do that for W=1. This means, W=1 effectively
enables -Winitializer-overrides by the clang's default. The same for
the other three.
Add comments in case people are confused with the code.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
2019-09-01 01:25:54 +09:00
|
|
|
|
|
|
|
|
endif
|
|
|
|
|
|
|
|
|
|
#
|
|
|
|
|
# W=2 - warnings which occur quite often but may still be relevant
|
|
|
|
|
#
|
2019-09-01 01:25:55 +09:00
|
|
|
ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
|
kbuild: refactor scripts/Makefile.extrawarn
Instead of the warning-[123] magic, let's accumulate compiler options
to KBUILD_CFLAGS directly as the top Makefile does. I think this makes
it easier to understand what is going on in this file.
This commit slightly changes the behavior, I think all of which are OK.
[1] Currently, cc-option calls are needlessly evaluated. For example,
warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
needs evaluating only when W=3, but it is actually evaluated for
W=1, W=2 as well. With this commit, only relevant cc-option calls
will be evaluated. This is a slight optimization.
[2] Currently, unsupported level like W=4 is checked by:
$(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
This will no longer be checked, but I do not think it is a big
deal.
[3] Currently, 4 Clang warnings (Winitializer-overrides, Wformat,
Wsign-compare, Wformat-zero-length) are shown by any of W=1, W=2,
and W=3. With this commit, they will be warned only by W=1. I
think this is a more correct behavior since each warning belongs
to only one group.
For understanding this commit correctly:
We have 3 warning groups, W=1, W=2, and W=3. You may think W=3 has a
higher level than W=1, but they are actually independent. If you like,
you can combine them like W=13. To enable all the warnings, you can
pass W=123. It is shown by 'make help', but not noticed much. Since we
support W= combination, there should not exist intersection among the
three groups. If we enable Winitializer-overrides for W=1, we do not
need to for W=2 or W=3. This is the reason why I think the change [3]
makes sense.
The documentation says -Winitializer-overrides is enabled by default.
(https://clang.llvm.org/docs/DiagnosticsReference.html#winitializer-overrides)
We negate it by passing -Wno-initializer-overrides for the normal
build, but we do not do that for W=1. This means, W=1 effectively
enables -Winitializer-overrides by the clang's default. The same for
the other three.
Add comments in case people are confused with the code.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
2019-09-01 01:25:54 +09:00
|
|
|
|
|
|
|
|
KBUILD_CFLAGS += -Wdisabled-optimization
|
|
|
|
|
KBUILD_CFLAGS += -Wshadow
|
|
|
|
|
KBUILD_CFLAGS += $(call cc-option, -Wlogical-op)
|
|
|
|
|
KBUILD_CFLAGS += $(call cc-option, -Wunused-macros)
|
|
|
|
|
|
kbuild: allow Clang to find unused static inline functions for W=1 build
GCC and Clang have different policy for -Wunused-function; GCC does not
warn unused static inline functions at all whereas Clang does if they
are defined in source files instead of included headers although it has
been suppressed since commit abb2ea7dfd82 ("compiler, clang: suppress
warning for unused static inline functions").
We often miss to delete unused functions where 'static inline' is used
in *.c files since there is no tool to detect them. Unused code remains
until somebody notices. For example, commit 075ddd75680f ("regulator:
core: remove unused rdev_get_supply()").
Let's remove __maybe_unused from the inline macro to allow Clang to
start finding unused static inline functions. For now, we do this only
for W=1 build since it is not a good idea to sprinkle warnings for the
normal build (e.g. 35 warnings for arch/x86/configs/x86_64_defconfig).
My initial attempt was to add -Wno-unused-function for no W= build
(https://lore.kernel.org/patchwork/patch/1120594/)
Nathan Chancellor pointed out that would weaken Clang's checks since
we would no longer get -Wunused-function without W=1. It is true GCC
would catch unused static non-inline functions, but it would weaken
Clang as a standalone compiler, at least.
Hence, here is a counter implementation. The current problem is, W=...
only controls compiler flags, which are globally effective. There is
no way to address only 'static inline' functions.
This commit defines KBUILD_EXTRA_WARN[123] corresponding to W=[123].
When KBUILD_EXTRA_WARN1 is defined, __maybe_unused is omitted from
the 'inline' macro.
The new macro __inline_maybe_unused makes the code a bit uglier, so I
hope we can remove it entirely after fixing most of the warnings.
If you contribute to code clean-up, please run "make CC=clang W=1"
and check -Wunused-function warnings. You will find lots of unused
functions.
Some of them are false-positives because the call-sites are disabled
by #ifdef. I do not like to abuse the inline keyword for suppressing
unused-function warnings because it is intended to be a hint for the
compiler optimization. I prefer #ifdef around the definition, or
__maybe_unused if #ifdef would make the code too ugly.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
2019-09-07 11:52:36 +09:00
|
|
|
KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2
|
|
|
|
|
|
2023-08-11 16:03:21 +02:00
|
|
|
else
|
|
|
|
|
|
|
|
|
|
# The following turn off the warnings enabled by -Wextra
|
|
|
|
|
KBUILD_CFLAGS += -Wno-missing-field-initializers
|
|
|
|
|
KBUILD_CFLAGS += -Wno-type-limits
|
|
|
|
|
KBUILD_CFLAGS += -Wno-shift-negative-value
|
|
|
|
|
|
kbuild: Move -Wenum-enum-conversion to W=2
-Wenum-enum-conversion was strengthened in clang-19 to warn for C, which
caused the kernel to move it to W=1 in commit 75b5ab134bb5 ("kbuild:
Move -Wenum-{compare-conditional,enum-conversion} into W=1") because
there were numerous instances that would break builds with -Werror.
Unfortunately, this is not a full solution, as more and more developers,
subsystems, and distributors are building with W=1 as well, so they
continue to see the numerous instances of this warning.
Since the move to W=1, there have not been many new instances that have
appeared through various build reports and the ones that have appeared
seem to be following similar existing patterns, suggesting that most
instances of this warning will not be real issues. The only alternatives
for silencing this warning are adding casts (which is generally seen as
an ugly practice) or refactoring the enums to macro defines or a unified
enum (which may be undesirable because of type safety in other parts of
the code).
Move the warning to W=2, where warnings that occur frequently but may be
relevant should reside.
Cc: stable@vger.kernel.org
Fixes: 75b5ab134bb5 ("kbuild: Move -Wenum-{compare-conditional,enum-conversion} into W=1")
Link: https://lore.kernel.org/ZwRA9SOcOjjLJcpi@google.com/
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2024-10-17 10:09:22 -07:00
|
|
|
ifdef CONFIG_CC_IS_CLANG
|
|
|
|
|
KBUILD_CFLAGS += -Wno-enum-enum-conversion
|
|
|
|
|
endif
|
|
|
|
|
|
2024-03-26 15:47:16 +01:00
|
|
|
ifdef CONFIG_CC_IS_GCC
|
2023-08-11 16:03:21 +02:00
|
|
|
KBUILD_CFLAGS += -Wno-maybe-uninitialized
|
|
|
|
|
endif
|
|
|
|
|
|
kbuild: refactor scripts/Makefile.extrawarn
Instead of the warning-[123] magic, let's accumulate compiler options
to KBUILD_CFLAGS directly as the top Makefile does. I think this makes
it easier to understand what is going on in this file.
This commit slightly changes the behavior, I think all of which are OK.
[1] Currently, cc-option calls are needlessly evaluated. For example,
warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
needs evaluating only when W=3, but it is actually evaluated for
W=1, W=2 as well. With this commit, only relevant cc-option calls
will be evaluated. This is a slight optimization.
[2] Currently, unsupported level like W=4 is checked by:
$(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
This will no longer be checked, but I do not think it is a big
deal.
[3] Currently, 4 Clang warnings (Winitializer-overrides, Wformat,
Wsign-compare, Wformat-zero-length) are shown by any of W=1, W=2,
and W=3. With this commit, they will be warned only by W=1. I
think this is a more correct behavior since each warning belongs
to only one group.
For understanding this commit correctly:
We have 3 warning groups, W=1, W=2, and W=3. You may think W=3 has a
higher level than W=1, but they are actually independent. If you like,
you can combine them like W=13. To enable all the warnings, you can
pass W=123. It is shown by 'make help', but not noticed much. Since we
support W= combination, there should not exist intersection among the
three groups. If we enable Winitializer-overrides for W=1, we do not
need to for W=2 or W=3. This is the reason why I think the change [3]
makes sense.
The documentation says -Winitializer-overrides is enabled by default.
(https://clang.llvm.org/docs/DiagnosticsReference.html#winitializer-overrides)
We negate it by passing -Wno-initializer-overrides for the normal
build, but we do not do that for W=1. This means, W=1 effectively
enables -Winitializer-overrides by the clang's default. The same for
the other three.
Add comments in case people are confused with the code.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
2019-09-01 01:25:54 +09:00
|
|
|
endif
|
|
|
|
|
|
|
|
|
|
#
|
|
|
|
|
# W=3 - more obscure warnings, can most likely be ignored
|
|
|
|
|
#
|
2019-09-01 01:25:55 +09:00
|
|
|
ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),)
|
kbuild: refactor scripts/Makefile.extrawarn
Instead of the warning-[123] magic, let's accumulate compiler options
to KBUILD_CFLAGS directly as the top Makefile does. I think this makes
it easier to understand what is going on in this file.
This commit slightly changes the behavior, I think all of which are OK.
[1] Currently, cc-option calls are needlessly evaluated. For example,
warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
needs evaluating only when W=3, but it is actually evaluated for
W=1, W=2 as well. With this commit, only relevant cc-option calls
will be evaluated. This is a slight optimization.
[2] Currently, unsupported level like W=4 is checked by:
$(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
This will no longer be checked, but I do not think it is a big
deal.
[3] Currently, 4 Clang warnings (Winitializer-overrides, Wformat,
Wsign-compare, Wformat-zero-length) are shown by any of W=1, W=2,
and W=3. With this commit, they will be warned only by W=1. I
think this is a more correct behavior since each warning belongs
to only one group.
For understanding this commit correctly:
We have 3 warning groups, W=1, W=2, and W=3. You may think W=3 has a
higher level than W=1, but they are actually independent. If you like,
you can combine them like W=13. To enable all the warnings, you can
pass W=123. It is shown by 'make help', but not noticed much. Since we
support W= combination, there should not exist intersection among the
three groups. If we enable Winitializer-overrides for W=1, we do not
need to for W=2 or W=3. This is the reason why I think the change [3]
makes sense.
The documentation says -Winitializer-overrides is enabled by default.
(https://clang.llvm.org/docs/DiagnosticsReference.html#winitializer-overrides)
We negate it by passing -Wno-initializer-overrides for the normal
build, but we do not do that for W=1. This means, W=1 effectively
enables -Winitializer-overrides by the clang's default. The same for
the other three.
Add comments in case people are confused with the code.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
2019-09-01 01:25:54 +09:00
|
|
|
|
|
|
|
|
KBUILD_CFLAGS += -Wbad-function-cast
|
2020-10-26 23:03:13 +01:00
|
|
|
KBUILD_CFLAGS += -Wcast-align
|
kbuild: refactor scripts/Makefile.extrawarn
Instead of the warning-[123] magic, let's accumulate compiler options
to KBUILD_CFLAGS directly as the top Makefile does. I think this makes
it easier to understand what is going on in this file.
This commit slightly changes the behavior, I think all of which are OK.
[1] Currently, cc-option calls are needlessly evaluated. For example,
warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
needs evaluating only when W=3, but it is actually evaluated for
W=1, W=2 as well. With this commit, only relevant cc-option calls
will be evaluated. This is a slight optimization.
[2] Currently, unsupported level like W=4 is checked by:
$(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
This will no longer be checked, but I do not think it is a big
deal.
[3] Currently, 4 Clang warnings (Winitializer-overrides, Wformat,
Wsign-compare, Wformat-zero-length) are shown by any of W=1, W=2,
and W=3. With this commit, they will be warned only by W=1. I
think this is a more correct behavior since each warning belongs
to only one group.
For understanding this commit correctly:
We have 3 warning groups, W=1, W=2, and W=3. You may think W=3 has a
higher level than W=1, but they are actually independent. If you like,
you can combine them like W=13. To enable all the warnings, you can
pass W=123. It is shown by 'make help', but not noticed much. Since we
support W= combination, there should not exist intersection among the
three groups. If we enable Winitializer-overrides for W=1, we do not
need to for W=2 or W=3. This is the reason why I think the change [3]
makes sense.
The documentation says -Winitializer-overrides is enabled by default.
(https://clang.llvm.org/docs/DiagnosticsReference.html#winitializer-overrides)
We negate it by passing -Wno-initializer-overrides for the normal
build, but we do not do that for W=1. This means, W=1 effectively
enables -Winitializer-overrides by the clang's default. The same for
the other three.
Add comments in case people are confused with the code.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
2019-09-01 01:25:54 +09:00
|
|
|
KBUILD_CFLAGS += -Wcast-qual
|
|
|
|
|
KBUILD_CFLAGS += -Wconversion
|
|
|
|
|
KBUILD_CFLAGS += -Wpacked
|
|
|
|
|
KBUILD_CFLAGS += -Wpadded
|
|
|
|
|
KBUILD_CFLAGS += -Wpointer-arith
|
|
|
|
|
KBUILD_CFLAGS += -Wredundant-decls
|
2020-07-21 21:57:43 -07:00
|
|
|
KBUILD_CFLAGS += -Wsign-compare
|
kbuild: refactor scripts/Makefile.extrawarn
Instead of the warning-[123] magic, let's accumulate compiler options
to KBUILD_CFLAGS directly as the top Makefile does. I think this makes
it easier to understand what is going on in this file.
This commit slightly changes the behavior, I think all of which are OK.
[1] Currently, cc-option calls are needlessly evaluated. For example,
warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
needs evaluating only when W=3, but it is actually evaluated for
W=1, W=2 as well. With this commit, only relevant cc-option calls
will be evaluated. This is a slight optimization.
[2] Currently, unsupported level like W=4 is checked by:
$(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
This will no longer be checked, but I do not think it is a big
deal.
[3] Currently, 4 Clang warnings (Winitializer-overrides, Wformat,
Wsign-compare, Wformat-zero-length) are shown by any of W=1, W=2,
and W=3. With this commit, they will be warned only by W=1. I
think this is a more correct behavior since each warning belongs
to only one group.
For understanding this commit correctly:
We have 3 warning groups, W=1, W=2, and W=3. You may think W=3 has a
higher level than W=1, but they are actually independent. If you like,
you can combine them like W=13. To enable all the warnings, you can
pass W=123. It is shown by 'make help', but not noticed much. Since we
support W= combination, there should not exist intersection among the
three groups. If we enable Winitializer-overrides for W=1, we do not
need to for W=2 or W=3. This is the reason why I think the change [3]
makes sense.
The documentation says -Winitializer-overrides is enabled by default.
(https://clang.llvm.org/docs/DiagnosticsReference.html#winitializer-overrides)
We negate it by passing -Wno-initializer-overrides for the normal
build, but we do not do that for W=1. This means, W=1 effectively
enables -Winitializer-overrides by the clang's default. The same for
the other three.
Add comments in case people are confused with the code.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
2019-09-01 01:25:54 +09:00
|
|
|
KBUILD_CFLAGS += -Wswitch-default
|
|
|
|
|
|
kbuild: allow Clang to find unused static inline functions for W=1 build
GCC and Clang have different policy for -Wunused-function; GCC does not
warn unused static inline functions at all whereas Clang does if they
are defined in source files instead of included headers although it has
been suppressed since commit abb2ea7dfd82 ("compiler, clang: suppress
warning for unused static inline functions").
We often miss to delete unused functions where 'static inline' is used
in *.c files since there is no tool to detect them. Unused code remains
until somebody notices. For example, commit 075ddd75680f ("regulator:
core: remove unused rdev_get_supply()").
Let's remove __maybe_unused from the inline macro to allow Clang to
start finding unused static inline functions. For now, we do this only
for W=1 build since it is not a good idea to sprinkle warnings for the
normal build (e.g. 35 warnings for arch/x86/configs/x86_64_defconfig).
My initial attempt was to add -Wno-unused-function for no W= build
(https://lore.kernel.org/patchwork/patch/1120594/)
Nathan Chancellor pointed out that would weaken Clang's checks since
we would no longer get -Wunused-function without W=1. It is true GCC
would catch unused static non-inline functions, but it would weaken
Clang as a standalone compiler, at least.
Hence, here is a counter implementation. The current problem is, W=...
only controls compiler flags, which are globally effective. There is
no way to address only 'static inline' functions.
This commit defines KBUILD_EXTRA_WARN[123] corresponding to W=[123].
When KBUILD_EXTRA_WARN1 is defined, __maybe_unused is omitted from
the 'inline' macro.
The new macro __inline_maybe_unused makes the code a bit uglier, so I
hope we can remove it entirely after fixing most of the warnings.
If you contribute to code clean-up, please run "make CC=clang W=1"
and check -Wunused-function warnings. You will find lots of unused
functions.
Some of them are false-positives because the call-sites are disabled
by #ifdef. I do not like to abuse the inline keyword for suppressing
unused-function warnings because it is intended to be a hint for the
compiler optimization. I prefer #ifdef around the definition, or
__maybe_unused if #ifdef would make the code too ugly.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
2019-09-07 11:52:36 +09:00
|
|
|
KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3
|
|
|
|
|
|
2023-08-11 16:03:21 +02:00
|
|
|
else
|
|
|
|
|
|
|
|
|
|
# The following turn off the warnings enabled by -Wextra
|
|
|
|
|
KBUILD_CFLAGS += -Wno-sign-compare
|
2024-04-15 14:20:32 +02:00
|
|
|
KBUILD_CFLAGS += -Wno-unused-parameter
|
2023-08-11 16:03:21 +02:00
|
|
|
|
2014-04-14 18:27:10 +09:00
|
|
|
endif
|
2022-04-08 10:46:07 +02:00
|
|
|
|
|
|
|
|
#
|
2025-08-14 12:14:42 +02:00
|
|
|
# W=e and CONFIG_WERROR - error out on warnings
|
2022-04-08 10:46:07 +02:00
|
|
|
#
|
2025-08-14 12:14:42 +02:00
|
|
|
ifneq ($(findstring e, $(KBUILD_EXTRA_WARN))$(CONFIG_WERROR),)
|
2022-04-08 10:46:07 +02:00
|
|
|
|
2025-08-14 12:14:41 +02:00
|
|
|
KBUILD_CPPFLAGS += -Werror
|
2025-08-14 12:14:44 +02:00
|
|
|
KBUILD_AFLAGS += -Wa,--fatal-warnings
|
|
|
|
|
KBUILD_LDFLAGS += --fatal-warnings
|
2025-08-14 12:14:45 +02:00
|
|
|
KBUILD_USERCFLAGS += -Werror
|
|
|
|
|
KBUILD_USERLDFLAGS += -Wl,--fatal-warnings
|
2025-08-14 12:14:43 +02:00
|
|
|
KBUILD_RUSTFLAGS += -Dwarnings
|
2022-04-08 10:46:07 +02:00
|
|
|
|
2025-10-06 14:39:56 -07:00
|
|
|
# While hostprog flags are used during build bootstrapping (thus should not
|
|
|
|
|
# depend on CONFIG_ symbols), -Werror is disruptive and should be opted into.
|
|
|
|
|
# Only apply -Werror to hostprogs built after the initial Kconfig stage.
|
2025-08-14 12:14:46 +02:00
|
|
|
KBUILD_HOSTCFLAGS += -Werror
|
|
|
|
|
KBUILD_HOSTLDFLAGS += -Wl,--fatal-warnings
|
|
|
|
|
KBUILD_HOSTRUSTFLAGS += -Dwarnings
|
2025-10-06 14:39:56 -07:00
|
|
|
|
|
|
|
|
endif
|