From: Arnd Bergmann <arnd(a)arndb.de>
During a patch discussion, Linus brought up the option of changing
the C standard version from gnu89 to gnu99, which allows using variable
declaration inside of a for() loop. While the C99, C11 and later standards
introduce many other features, most of these are already available in
gnu89 as GNU extensions as well.
An earlier attempt to do this when gcc-5 started defaulting to
-std=gnu11 failed because at the time that caused warnings about
designated initializers with older compilers. Now that gcc-5.1 is the
minimum compiler version used for building kernels, that is no longer a
concern. Similarly, the behavior of 'inline' functions changes between
gnu89 and gnu11, but this was taken care of by defining 'inline' to
include __attribute__((gnu_inline)) in order to allow building with
clang a while ago.
One minor issue that remains is an added gcc warning for shifts of
negative integers when building with -Werror, which happens with the
'make W=1' option, as well as for three drivers in the kernel that always
enable -Werror, but it was only observed with the i915 driver so far.
To be on the safe side, add -Wno-shift-negative-value to any -Wextra
in a Makefile.
Nathan Chancellor reported an additional -Wdeclaration-after-statement
warning that appears in a system header on arm, this still needs a
workaround.
The differences between gnu99, gnu11, gnu1x and gnu17 are fairly
minimal and mainly impact warnings at the -Wpedantic level that the
kernel never enables. Between these, gnu11 is the newest version
that is supported by all supported compiler versions, though it is
only the default on gcc-5, while all other supported versions of
gcc or clang default to gnu1x/gnu17.
Link: https://lore.kernel.org/lkml/CAHk-=wiyCH7xeHcmiFJ-YgXUy2Jaj7pnkdKpcovt8fYbV…
Link: https://github.com/ClangBuiltLinux/linux/issues/1603
Suggested-by: Linus Torvalds <torvalds(a)linux-foundation.org>
Cc: Masahiro Yamada <masahiroy(a)kernel.org>
Cc: linux-kbuild(a)vger.kernel.org
Cc: llvm(a)lists.linux.dev
Signed-off-by: Arnd Bergmann <arnd(a)arndb.de>
---
[v2]
- added -std=gnu11 back, rather than just relying on the default
- minor changes to changelog text
---
Documentation/process/programming-language.rst | 4 ++--
.../translations/it_IT/process/programming-language.rst | 4 ++--
.../translations/zh_CN/process/programming-language.rst | 4 ++--
.../translations/zh_TW/process/programming-language.rst | 4 ++--
Makefile | 6 +++---
arch/arm64/kernel/vdso32/Makefile | 2 +-
drivers/gpu/drm/i915/Makefile | 1 +
drivers/staging/greybus/tools/Makefile | 3 ++-
fs/btrfs/Makefile | 1 +
scripts/Makefile.extrawarn | 1 +
10 files changed, 17 insertions(+), 13 deletions(-)
diff --git a/Documentation/process/programming-language.rst b/Documentation/process/programming-language.rst
index ec474a70a02f..894f2a6eb9db 100644
--- a/Documentation/process/programming-language.rst
+++ b/Documentation/process/programming-language.rst
@@ -5,8 +5,8 @@ Programming Language
The kernel is written in the C programming language [c-language]_.
More precisely, the kernel is typically compiled with ``gcc`` [gcc]_
-under ``-std=gnu89`` [gcc-c-dialect-options]_: the GNU dialect of ISO C90
-(including some C99 features). ``clang`` [clang]_ is also supported, see
+under ``-std=gnu11`` [gcc-c-dialect-options]_: the GNU dialect of ISO C11
+(including some C17 features). ``clang`` [clang]_ is also supported, see
docs on :ref:`Building Linux with Clang/LLVM <kbuild_llvm>`.
This dialect contains many extensions to the language [gnu-extensions]_,
diff --git a/Documentation/translations/it_IT/process/programming-language.rst b/Documentation/translations/it_IT/process/programming-language.rst
index 41db2598ce11..aa21097737ae 100644
--- a/Documentation/translations/it_IT/process/programming-language.rst
+++ b/Documentation/translations/it_IT/process/programming-language.rst
@@ -10,8 +10,8 @@ Linguaggio di programmazione
Il kernel è scritto nel linguaggio di programmazione C [it-c-language]_.
Più precisamente, il kernel viene compilato con ``gcc`` [it-gcc]_ usando
-l'opzione ``-std=gnu89`` [it-gcc-c-dialect-options]_: il dialetto GNU
-dello standard ISO C90 (con l'aggiunta di alcune funzionalità da C99).
+l'opzione ``-std=gnu11`` [it-gcc-c-dialect-options]_: il dialetto GNU
+dello standard ISO C11 (con l'aggiunta di alcune funzionalità da C17).
Linux supporta anche ``clang`` [it-clang]_, leggete la documentazione
:ref:`Building Linux with Clang/LLVM <kbuild_llvm>`.
diff --git a/Documentation/translations/zh_CN/process/programming-language.rst b/Documentation/translations/zh_CN/process/programming-language.rst
index 2a47a1d2ec20..58d2b3bd2d85 100644
--- a/Documentation/translations/zh_CN/process/programming-language.rst
+++ b/Documentation/translations/zh_CN/process/programming-language.rst
@@ -9,8 +9,8 @@
============
内核是用C语言 :ref:`c-language <cn_c-language>` 编写的。更准确地说,内核通常是用 :ref:`gcc <cn_gcc>`
-在 ``-std=gnu89`` :ref:`gcc-c-dialect-options <cn_gcc-c-dialect-options>` 下编译的:ISO C90的 GNU 方言(
-包括一些C99特性)
+在 ``-std=gnu11`` :ref:`gcc-c-dialect-options <cn_gcc-c-dialect-options>` 下编译的:ISO C11的 GNU 方言(
+包括一些C17特性)
这种方言包含对语言 :ref:`gnu-extensions <cn_gnu-extensions>` 的许多扩展,当然,它们许多都在内核中使用。
diff --git a/Documentation/translations/zh_TW/process/programming-language.rst b/Documentation/translations/zh_TW/process/programming-language.rst
index 54e3699eadf8..235de05f7e2c 100644
--- a/Documentation/translations/zh_TW/process/programming-language.rst
+++ b/Documentation/translations/zh_TW/process/programming-language.rst
@@ -12,8 +12,8 @@
============
內核是用C語言 :ref:`c-language <tw_c-language>` 編寫的。更準確地說,內核通常是用 :ref:`gcc <tw_gcc>`
-在 ``-std=gnu89`` :ref:`gcc-c-dialect-options <tw_gcc-c-dialect-options>` 下編譯的:ISO C90的 GNU 方言(
-包括一些C99特性)
+在 ``-std=gnu11`` :ref:`gcc-c-dialect-options <tw_gcc-c-dialect-options>` 下編譯的:ISO C11的 GNU 方言(
+包括一些C17特性)
這種方言包含對語言 :ref:`gnu-extensions <tw_gnu-extensions>` 的許多擴展,當然,它們許多都在內核中使用。
diff --git a/Makefile b/Makefile
index 289ce2be8032..66496eaeb9ec 100644
--- a/Makefile
+++ b/Makefile
@@ -432,7 +432,7 @@ HOSTCXX = g++
endif
export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
- -O2 -fomit-frame-pointer -std=gnu89
+ -O2 -fomit-frame-pointer -std=gnu11
export KBUILD_USERLDFLAGS :=
KBUILD_HOSTCFLAGS := $(KBUILD_USERCFLAGS) $(HOST_LFS_CFLAGS) $(HOSTCFLAGS)
@@ -515,7 +515,7 @@ KBUILD_CFLAGS := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \
-fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE \
-Werror=implicit-function-declaration -Werror=implicit-int \
-Werror=return-type -Wno-format-security \
- -std=gnu89
+ -std=gnu11
KBUILD_CPPFLAGS := -D__KERNEL__
KBUILD_AFLAGS_KERNEL :=
KBUILD_CFLAGS_KERNEL :=
@@ -782,7 +782,7 @@ KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
ifdef CONFIG_CC_IS_CLANG
KBUILD_CPPFLAGS += -Qunused-arguments
-# The kernel builds with '-std=gnu89' so use of GNU extensions is acceptable.
+# The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable.
KBUILD_CFLAGS += -Wno-gnu
# CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the
# source of a reference will be _MergedGlobals and not on of the whitelisted names.
diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
index 6c01b63ff56d..9378ea055bf2 100644
--- a/arch/arm64/kernel/vdso32/Makefile
+++ b/arch/arm64/kernel/vdso32/Makefile
@@ -68,7 +68,7 @@ VDSO_CFLAGS += -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
-fno-strict-aliasing -fno-common \
-Werror-implicit-function-declaration \
-Wno-format-security \
- -std=gnu89
+ -std=gnu11
VDSO_CFLAGS += -O2
# Some useful compiler-dependent flags from top-level Makefile
VDSO_CFLAGS += $(call cc32-option,-Wdeclaration-after-statement,)
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 1b62b9f65196..1618a6e0af4e 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -17,6 +17,7 @@ subdir-ccflags-y += -Wno-unused-parameter
subdir-ccflags-y += -Wno-type-limits
subdir-ccflags-y += -Wno-missing-field-initializers
subdir-ccflags-y += -Wno-sign-compare
+subdir-ccflags-y += -Wno-shift-negative-value
subdir-ccflags-y += $(call cc-disable-warning, unused-but-set-variable)
subdir-ccflags-y += $(call cc-disable-warning, frame-address)
subdir-ccflags-$(CONFIG_DRM_I915_WERROR) += -Werror
diff --git a/drivers/staging/greybus/tools/Makefile b/drivers/staging/greybus/tools/Makefile
index ad0ae8053b79..a3bbd73171f2 100644
--- a/drivers/staging/greybus/tools/Makefile
+++ b/drivers/staging/greybus/tools/Makefile
@@ -12,7 +12,8 @@ CFLAGS += -std=gnu99 -Wall -Wextra -g \
-Wredundant-decls \
-Wcast-align \
-Wsign-compare \
- -Wno-missing-field-initializers
+ -Wno-missing-field-initializers \
+ -Wno-shift-negative-value
CC := $(CROSS_COMPILE)gcc
diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index 4188ba3fd8c3..99f9995670ea 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -17,6 +17,7 @@ subdir-ccflags-y += $(condflags)
subdir-ccflags-y += -Wno-missing-field-initializers
subdir-ccflags-y += -Wno-sign-compare
subdir-ccflags-y += -Wno-type-limits
+subdir-ccflags-y += -Wno-shift-negative-value
obj-$(CONFIG_BTRFS_FS) := btrfs.o
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 8be892887d71..650d0b8ceec3 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -36,6 +36,7 @@ KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation)
KBUILD_CFLAGS += -Wno-missing-field-initializers
KBUILD_CFLAGS += -Wno-sign-compare
KBUILD_CFLAGS += -Wno-type-limits
+KBUILD_CFLAGS += -Wno-shift-negative-value
KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
--
2.29.2
Correct misspelling in comment. Issue found with checkpatch.
Signed-off-by: Nickalas Cason <nickalas(a)cason.dev>
---
drivers/staging/greybus/arche-platform.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/staging/greybus/arche-platform.c b/drivers/staging/greybus/arche-platform.c
index e374dfc0c92f..fcbd5f71eff2 100644
--- a/drivers/staging/greybus/arche-platform.c
+++ b/drivers/staging/greybus/arche-platform.c
@@ -591,7 +591,7 @@ static __maybe_unused int arche_platform_suspend(struct device *dev)
static __maybe_unused int arche_platform_resume(struct device *dev)
{
/*
- * Atleast for ES2 we have to meet the delay requirement between
+ * At least for ES2 we have to meet the delay requirement between
* unipro switch and AP bridge init, depending on whether bridge is in
* OFF state or standby state.
*
--
2.35.1
The first patch corrects a typo in a comment. The second patch removes
an empty callback function.
Changes in version 3:
Edited the second patch in the patchset to remove the entire empty
function with a void return type instead of removing just the return
statement within the function.
Jaehee Park (2):
staging: greybus: correct typo in comment
staging: greybus: remove empty callback function
drivers/staging/greybus/arche-apb-ctrl.c | 2 +-
drivers/staging/greybus/audio_codec.c | 8 --------
2 files changed, 1 insertion(+), 9 deletions(-)
--
2.25.1
Make the envp char array a const in the send_add_uevent function since
the value will never change. It will remain an array of the pointers to
the various char arrays.
There does exist a warning when running the checkpatch script to
make this a static variable, but there does not appear to be any advantage
to make this change.
Signed-off-by: Ian Cowan <ian(a)linux.cowan.aero>
---
drivers/staging/greybus/audio_manager_module.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/staging/greybus/audio_manager_module.c b/drivers/staging/greybus/audio_manager_module.c
index 0a0f0a394c84..c9d223b0e541 100644
--- a/drivers/staging/greybus/audio_manager_module.c
+++ b/drivers/staging/greybus/audio_manager_module.c
@@ -159,7 +159,7 @@ static void send_add_uevent(struct gb_audio_manager_module *module)
char ip_devices_string[64];
char op_devices_string[64];
- char *envp[] = {
+ const char *envp[] = {
name_string,
vid_string,
pid_string,
--
2.32.0
Zero-length and one-element arrays are deprecated. Flexible-array
members should be used instead. Flexible-array members are
recommended because this is the way the kernel expects dynamically
sized trailing elements to be declared.
Refer to Documentation/process/deprecated.rst.
Change the zero-length array, buf, in the struct
gb_usb_hub_control_response to a flexible array. And add wLength as a
member of the struct so that the struct is not a zero-sized struct.
Issue found by flexible_array coccinelle script.
Signed-off-by: Jaehee Park <jhpark1013(a)gmail.com>
---
I have a question for the authors:
I saw a fixme comment in the hub_control function in usb.c:
/ FIXME: handle unspecified lengths /
I was wondering why this comment was left there?
In this patch, I'm using this struct:
struct gb_usb_hub_control_response {
__le16 wLength;
u8 buf[];
};
And instead of using response_size, I'm doing this:
struct gb_usb_hub_control_response *response;
And using sizeof(*response) as the input to gb_operation_create.
Would the flexible array address the handling of unspecified lengths
issue (in the fixme comment)?
drivers/staging/greybus/usb.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/staging/greybus/usb.c b/drivers/staging/greybus/usb.c
index 8e9d9d59a357..d0b2422401df 100644
--- a/drivers/staging/greybus/usb.c
+++ b/drivers/staging/greybus/usb.c
@@ -27,7 +27,8 @@ struct gb_usb_hub_control_request {
};
struct gb_usb_hub_control_response {
- u8 buf[0];
+ __le16 wLength;
+ u8 buf[];
};
struct gb_usb_device {
@@ -102,16 +103,14 @@ static int hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue, u16 wIndex,
struct gb_operation *operation;
struct gb_usb_hub_control_request *request;
struct gb_usb_hub_control_response *response;
- size_t response_size;
int ret;
/* FIXME: handle unspecified lengths */
- response_size = sizeof(*response) + wLength;
operation = gb_operation_create(dev->connection,
GB_USB_TYPE_HUB_CONTROL,
sizeof(*request),
- response_size,
+ sizeof(*response),
GFP_KERNEL);
if (!operation)
return -ENOMEM;
--
2.25.1
The first patch corrects a typo in a comment. The second patch removes
an unneeded return.
Changes in version 2:
- edited the subject to be more concise.
- edited the log message to be more descriptive.
Jaehee Park (2):
staging: greybus: correct typo in comment
staging: greybus: remove unneeded return
drivers/staging/greybus/arche-apb-ctrl.c | 2 +-
drivers/staging/greybus/audio_codec.c | 1 -
2 files changed, 1 insertion(+), 2 deletions(-)
--
2.25.1