linux-toradex.git/scripts/Makefile.extrawarn, branch toradex_5.3.y

kbuild: Remove unnecessary -Wno-unused-value

2019-06-23T18:43:03+00:00

This flag turns off several other warnings that would
be useful. Most notably -warn_unused_result is disabled.
All of the following warnings are currently disabled:

UnusedValue
|-UnusedComparison
  |-warn_unused_comparison
|-UnusedResult
  |-warn_unused_result
|-UnevaluatedExpression
  |-PotentiallyEvaluatedExpression
    |-warn_side_effects_typeid
  |-warn_side_effects_unevaluated_context
|-warn_unused_expr
|-warn_unused_voidptr
|-warn_unused_container_subscript_expr
|-warn_unused_call

With this flag removed there are ~10 warnings.
Patches have been submitted for each of these warnings.

Reported-by: Nick Desaulniers 
Cc: clang-built-linux@googlegroups.com
Link: https://github.com/ClangBuiltLinux/linux/issues/520
Signed-off-by: Nathan Huckleberry 
Reviewed-by: Nick Desaulniers 
Signed-off-by: Masahiro Yamada

kbuild: Enable -Wuninitialized

2019-06-23T18:43:03+00:00

This helps fine very dodgy behavior through both -Wuninitialized
(warning that a variable is always uninitialized) and
-Wsometimes-uninitialized (warning that a variable is sometimes
uninitialized, like GCC's -Wmaybe-uninitialized). These warnings
catch things that GCC doesn't such as:

https://lore.kernel.org/lkml/86649ee4-9794-77a3-502c-f4cd10019c36@lca.pw/

We very much want to catch these so turn this warning on so that CI is
aware of it.

Link: https://github.com/ClangBuiltLinux/linux/issues/381
Signed-off-by: Nathan Chancellor 
Reviewed-by: Nick Desaulniers 
Signed-off-by: Masahiro Yamada

kbuild: Remove -Waggregate-return from scripts/Makefile.extrawarn

2019-06-09T06:07:52+00:00

It makes little sense to pass -Waggregate-return these days since large
part of the linux kernel rely on returning struct(s). For instance:

  ../include/linux/timekeeping.h: In function 'show_uptime':
  ../include/linux/ktime.h:91:34: error: function call has aggregate value [-Werror=aggregate-return]
   #define ktime_to_timespec64(kt)  ns_to_timespec64((kt))
                                    ^~~~~~~~~~~~~~~~~~~~~~
  ../include/linux/timekeeping.h:166:8: note: in expansion of macro 'ktime_to_timespec64'
    *ts = ktime_to_timespec64(ktime_get_coarse_boottime());

Remove this warning from W=2 completely.

Signed-off-by: Mathieu Malaterre 
Signed-off-by: Masahiro Yamada

kbuild: add all Clang-specific flags unconditionally

2019-05-18T02:49:53+00:00

We do not support old Clang versions. Upgrade your clang version
if any of these flags is unsupported.

Let's add all flags inside ifdef CONFIG_CC_IS_CLANG unconditionally.

Signed-off-by: Masahiro Yamada 
Reviewed-by: Sedat Dilek 
Reviewed-by: Nathan Chancellor 
Tested-by: Nick Desaulniers

kbuild: add some extra warning flags unconditionally

2019-05-18T02:49:53+00:00

These flags are documented in the GCC 4.6 manual, and recognized by
Clang as well. Let's rip off the cc-option / cc-disable-warning switches.

Signed-off-by: Masahiro Yamada 
Reviewed-by: Nathan Chancellor 
Tested-by: Nick Desaulniers

Merge tag 'kbuild-v4.20-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2018-11-03T17:47:33+00:00

Pull Kbuild updates from Masahiro Yamada:

 - clean-up leftovers in Kconfig files

 - remove stale oldnoconfig and silentoldconfig targets

 - remove unneeded cc-fullversion and cc-name variables

 - improve merge_config script to allow overriding option prefix

* tag 'kbuild-v4.20-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: remove cc-name variable
  kbuild: replace cc-name test with CONFIG_CC_IS_CLANG
  merge_config.sh: Allow to define config prefix
  kbuild: remove unused cc-fullversion variable
  kconfig: remove silentoldconfig target
  kconfig: remove oldnoconfig target
  powerpc: PCI_MSI needs PCI
  powerpc: remove CONFIG_MCA leftovers
  powerpc: remove CONFIG_PCI_QSPAN
  scsi: aha152x: rename the PCMCIA define

kbuild: replace cc-name test with CONFIG_CC_IS_CLANG

2018-11-02T13:49:00+00:00

Evaluating cc-name invokes the compiler every time even when you are
not compiling anything, like 'make help'. This is not efficient.

The compiler type has been already detected in the Kconfig stage.
Use CONFIG_CC_IS_CLANG, instead.

Signed-off-by: Masahiro Yamada 
Acked-by: Michael Ellerman  (powerpc)
Acked-by: Paul Burton  (MIPS)
Acked-by: Joel Stanley

Merge tag 'compiler-attributes-for-linus-4.20-rc1' of https://github.com/ojeda/linux

2018-11-02T01:34:46+00:00

Pull compiler attribute updates from Miguel Ojeda:
 "This is an effort to disentangle the include/linux/compiler*.h headers
  and bring them up to date.

  The main idea behind the series is to use feature checking macros
  (i.e. __has_attribute) instead of compiler version checks (e.g.
  GCC_VERSION), which are compiler-agnostic (so they can be shared,
  reducing the size of compiler-specific headers) and version-agnostic.

  Other related improvements have been performed in the headers as well,
  which on top of the use of __has_attribute it has amounted to a
  significant simplification of these headers (e.g. GCC_VERSION is now
  only guarding a few non-attribute macros).

  This series should also help the efforts to support compiling the
  kernel with clang and icc. A fair amount of documentation and comments
  have also been added, clarified or removed; and the headers are now
  more readable, which should help kernel developers in general.

  The series was triggered due to the move to gcc >= 4.6. In turn, this
  series has also triggered Sparse to gain the ability to recognize
  __has_attribute on its own.

  Finally, the __nonstring variable attribute series has been also
  applied on top; plus two related patches from Nick Desaulniers for
  unreachable() that came a bit afterwards"

* tag 'compiler-attributes-for-linus-4.20-rc1' of https://github.com/ojeda/linux:
  compiler-gcc: remove comment about gcc 4.5 from unreachable()
  compiler.h: update definition of unreachable()
  Compiler Attributes: ext4: remove local __nonstring definition
  Compiler Attributes: auxdisplay: panel: use __nonstring
  Compiler Attributes: enable -Wstringop-truncation on W=1 (gcc >= 8)
  Compiler Attributes: add support for __nonstring (gcc >= 8)
  Compiler Attributes: add MAINTAINERS entry
  Compiler Attributes: add Doc/process/programming-language.rst
  Compiler Attributes: remove uses of __attribute__ from compiler.h
  Compiler Attributes: KENTRY used twice the "used" attribute
  Compiler Attributes: use feature checks instead of version checks
  Compiler Attributes: add missing SPDX ID in compiler_types.h
  Compiler Attributes: remove unneeded sparse (__CHECKER__) tests
  Compiler Attributes: homogenize __must_be_array
  Compiler Attributes: remove unneeded tests
  Compiler Attributes: always use the extra-underscores syntax
  Compiler Attributes: remove unused attributes

Makefile: Globally enable VLA warning

2018-10-11T15:17:50+00:00

Now that Variable Length Arrays (VLAs) have been entirely removed[1]
from the kernel, enable the VLA warning globally. The only exceptions
to this are the KASan an UBSan tests which are explicitly checking that
VLAs trigger their respective tests.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Cc: Masahiro Yamada 
Cc: Andrew Morton 
Cc: David Airlie 
Cc: linux-kbuild@vger.kernel.org
Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Kees Cook

Compiler Attributes: enable -Wstringop-truncation on W=1 (gcc >= 8)

2018-09-30T18:14:04+00:00

Commit 217c3e019675 ("disable stringop truncation warnings for now")
disabled -Wstringop-truncation since it was too noisy.

Having __nonstring available allows us to let GCC know that a string
is not meant to be NUL-terminated, which helps suppressing some
-Wstringop-truncation warnings.

Note that using __nonstring actually triggers other warnings
(-Wstringop-overflow, which is on by default) which may be real
problems. Therefore, cleaning up -Wstringop-truncation warnings
also buys us the ability to uncover further potential problems.

To encourage the use of __nonstring, we put the warning back at W=1.
In the future, if we end up with a fairly warning-free tree,
we might want to enable it by default.

Tested-by: Sedat Dilek  # on top of v4.19-rc5, clang 7
Reviewed-by: Kees Cook 
Reviewed-by: Nick Desaulniers 
Reviewed-by: Luc Van Oostenryck 
Signed-off-by: Miguel Ojeda