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SubjectRe: [PATCH trivial] include/linux/coda.h: remove useless '#else'
On 07/31/2013 09:44 AM, Chen Gang wrote:
> On 07/30/2013 08:29 PM, Joe Perches wrote:
>> On Tue, 2013-07-30 at 15:30 +0800, Chen Gang wrote:
>>> '#else' is useless, need remove.
>>>
>>> Signed-off-by: Chen Gang <gang.chen@asianux.com>
>>> ---
>>> include/linux/coda.h | 1 -
>>> 1 files changed, 0 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/include/linux/coda.h b/include/linux/coda.h
>>> index cff544f..d30209b 100644
>>> --- a/include/linux/coda.h
>>> +++ b/include/linux/coda.h
>>> @@ -60,7 +60,6 @@ Mellon the rights to redistribute these changes without encumbrance.
>>>
>>> #if defined(__linux__)
>>> typedef unsigned long long u_quad_t;
>>> -#else
>>> #endif
>>> #include <uapi/linux/coda.h>
>>> #endif
>>
>> Why have the #if at all?
>>
>>
>>
>
> Hmm... some old version compilers do not define __linux__ automatically
> (e.g. or32-linux-gcc 4.5.1-or32-1.0rc1, which is the latest cross
> compiler for openrisc, though).
>
> If not define __linux__, the compiler will report error (u_quad_t is
> not defined).
>
> When we remove "#if defined(__linux__)" from "include/linux/coda.h",
> the compiler will not report error, and 'cdev_t' will be defined as
> 'dev_t', not 'u_quad_t' (I guess, it is an implicit bug).
>
>
> In "uapi/include/*", only "coda.h" has "#if defined(__linux__)", maybe
> they want multiple OS can share the same "coda.h" file (at least, we
> can not say it is a bad idea).
>
> Neither suitable to define __linux__ in "include/linux/coda.h".
>
>
> All together, I think:
>
> the direct cause:
> "uapi/include/coda.h" wants to share itself for multiple OS (so they need check __linux__).
> (in "uapi/include/*", only coda.h need check __linux__)
>
> the root cause:
> the compiler for linux should define __linux__ automatically, the latest version of gcc has done, but some of the old version is not.
> most of cross compilers have merged their code into gcc main tree, but still left some (e.g. openrisc).
> (at least, I can not build openrisc from gcc main tree correctly, but most of others can)
> some of latest cross compilers still use old version of gcc, (still not define __linux__ automatically).
>

Maybe what I said is incorrect (it is just my current understanding).

Welcome any other members' suggestions or completions for discussing and
checking.

Thanks.

>
> The related code in "uapi/linux/coda.h" is below:
>
> -------------------------------code begin-------------------------------
>
> 73 #if defined(DJGPP) || defined(__CYGWIN32__)
> 74 #ifdef KERNEL
> 75 typedef unsigned long u_long;
> 76 typedef unsigned int u_int;
> 77 typedef unsigned short u_short;
> 78 typedef u_long ino_t;
> 79 typedef u_long dev_t;
> 80 typedef void * caddr_t;
> 81 #ifdef DOS
> 82 typedef unsigned __int64 u_quad_t;
> 83 #else
> 84 typedef unsigned long long u_quad_t;
> 85 #endif
> 86
> 87 #define inline
> 88
> 89 struct timespec {
> 90 long ts_sec;
> 91 long ts_nsec;
> 92 };
> 93 #else /* DJGPP but not KERNEL */
> 94 #include <sys/time.h>
> 95 typedef unsigned long long u_quad_t;
> 96 #endif /* !KERNEL */
> 97 #endif /* !DJGPP */
> 98
> 99
> 100 #if defined(__linux__)
> 101 #include <linux/time.h>
> 102 #define cdev_t u_quad_t
> 103 #ifndef __KERNEL__
> 104 #if !defined(_UQUAD_T_) && (!defined(__GLIBC__) || __GLIBC__ < 2)
> 105 #define _UQUAD_T_ 1
> 106 typedef unsigned long long u_quad_t;
> 107 #endif
> 108 #endif /* __KERNEL__ */
> 109 #else
> 110 #define cdev_t dev_t
> 111 #endif
> 112
>
> -------------------------------code end---------------------------------
>
>
> Thanks.
>


--
Chen Gang


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