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SubjectRe: [PATCH 1/2] if_enabled.h: Add IF_ENABLED_OR_ELSE() and IF_ENABLED() macros
Hi Randy,

Le mar. 8 déc. 2020 à 9:39, Randy Dunlap <rdunlap@infradead.org> a
écrit :
> On 12/8/20 8:48 AM, Paul Cercueil wrote:
>>
>> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
>
> Hi Paul,
>
> Why not just add these 2 new macros to <linux/kconfig.h> ?
>
> Maybe you don't want to add the other 2 headers there also?

That means including <linux/compiler.h> in <linux/kconfig.h>, which
causes build failures:

LD vmlinux
SORTTAB vmlinux
SYSMAP System.map
AS arch/mips/boot/compressed/head.o
CC arch/mips/boot/compressed/decompress.o
CC arch/mips/boot/compressed/string.o
CC arch/mips/boot/compressed/dummy.o
OBJCOPY arch/mips/boot/compressed/vmlinux.bin
HOSTCC arch/mips/boot/compressed/calc_vmlinuz_load_addr
GZIP arch/mips/boot/compressed/vmlinux.bin.z
In file included from ./include/linux/kcsan-checks.h:7,
from ./include/asm-generic/rwonce.h:27,
from ./arch/mips/include/generated/asm/rwonce.h:1,
from ./include/linux/compiler.h:246,
from ././include/linux/kconfig.h:8,
from <command-line>:32:
/include/linux/compiler_attributes.h:64: warning: "__always_inline"
redefined
64 | #define __always_inline inline
__attribute__((__always_inline__))
|
In file included from ./include/linux/stddef.h:5,
from ./include/uapi/linux/posix_types.h:5,
from ./include/uapi/linux/types.h:14,
from ./include/linux/types.h:6,
from ./include/linux/kasan-checks.h:5,
from ./include/asm-generic/rwonce.h:26,
from ./arch/mips/include/generated/asm/rwonce.h:1,
from ./include/linux/compiler.h:246,
from ././include/linux/kconfig.h:8,
from <command-line>:32:
/include/uapi/linux/stddef.h:5: note: this is the location of the
previous definition
5 | #define __always_inline inline
|
In file included from ./arch/mips/include/generated/asm/rwonce.h:1,
from ./include/linux/compiler.h:246,
from ././include/linux/kconfig.h:8,
from <command-line>:32:
/include/asm-generic/rwonce.h:64:31: error: expected ‘;’ before
‘unsigned’
64 | static __no_sanitize_or_inline
| ^
| ;
65 | unsigned long __read_once_word_nocheck(const void *addr)
| ~~~~~~~~
/include/asm-generic/rwonce.h:65:15: warning: no previous prototype
for ‘__read_once_word_nocheck’ [-Wmissing-prototypes]
65 | unsigned long __read_once_word_nocheck(const void *addr)
| ^~~~~~~~~~~~~~~~~~~~~~~~
/include/asm-generic/rwonce.h:82:28: error: expected ‘;’ before
‘unsigned’
82 | static __no_kasan_or_inline
| ^
| ;
83 | unsigned long read_word_at_a_time(const void *addr)
| ~~~~~~~~
/include/asm-generic/rwonce.h:83:15: warning: no previous prototype
for ‘read_word_at_a_time’ [-Wmissing-prototypes]
83 | unsigned long read_word_at_a_time(const void *addr)
| ^~~~~~~~~~~~~~~~~~~


That's why I opted for a new header.

Cheers,
-Paul

>> ---
>> include/linux/if_enabled.h | 22 ++++++++++++++++++++++
>> 1 file changed, 22 insertions(+)
>> create mode 100644 include/linux/if_enabled.h
>>
>> diff --git a/include/linux/if_enabled.h b/include/linux/if_enabled.h
>> new file mode 100644
>> index 000000000000..8189d1402340
>> --- /dev/null
>> +++ b/include/linux/if_enabled.h
>> @@ -0,0 +1,22 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +#ifndef __LINUX_IF_ENABLED_H
>> +#define __LINUX_IF_ENABLED_H
>> +
>> +#include <linux/build_bug.h>
>> +#include <linux/compiler_types.h>
>> +#include <linux/kconfig.h>
>> +
>> +/*
>> + * IF_ENABLED_OR_ELSE(CONFIG_FOO, a, b) evaluates to (a) if
>> CONFIG_FOO is set
>> + * to 'y' or 'm', (b) otherwise.
>> + */
>> +#define IF_ENABLED_OR_ELSE(option, a, b) \
>> + (BUILD_BUG_ON_ZERO(__same_type((a), (b))) || IS_ENABLED(option) ?
>> (a) : (b))
>> +
>> +/*
>> + * IF_ENABLED(CONFIG_FOO, ptr) evaluates to (ptr) if CONFIG_FOO is
>> set to 'y'
>> + * or 'm', NULL otherwise.
>> + */
>> +#define IF_ENABLED(option, ptr) IF_ENABLED_OR_ELSE(option, ptr,
>> NULL)
>> +
>> +#endif /* __LINUX_IF_ENABLED_H */
>
>
> thanks.
> --
> ~Randy
>


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