Arnd Bergmann wrote:
> On Monday 25 May 2009 18:54:42 Michal Simek wrote:
>> Hi Arnd, cc: John
>>
>> From asm-generic/posix_types.h
>>
>> 17 #ifndef __kernel_mode_t
>> 18 typedef unsigned int __kernel_mode_t;
>> 19 #endif
>>
>> This structure is not aligned properly because of pad2.
>>
>> 19 struct ipc64_perm {
>> 20 __kernel_key_t key;
>> 21 __kernel_uid32_t uid;
>> 22 __kernel_gid32_t gid;
>> 23 __kernel_uid32_t cuid;
>> 24 __kernel_gid32_t cgid;
>> 25 __kernel_mode_t mode;
>> 26 unsigned short __pad1;
>> 27 unsigned short seq;
>> 28 unsigned short __pad2;
>> 29 unsigned long __unused1;
>> 30 unsigned long __unused2;
>> 31 };
>>
>> I think we should remove __pad1.
>> What do you think?
>
> Right, well spotted.
>
> I'd like to keep the struct ipc64_perm compatible with most architectures, so
> maybe we can play a little trick here:
>
>> Here is proposed struct.
>> struct ipc64_perm {
>> __kernel_key_t key;
>> __kernel_uid32_t uid;
>> __kernel_gid32_t gid;
>> __kernel_uid32_t cuid;
>> __kernel_gid32_t cgid;
>> __kernel_mode_t mode;
>
> + unsigned char __pad1[4 - sizeof(__kernel_mode_t)];
>
>> unsigned short seq;
>> unsigned short __pad2;
>> unsigned long __unused1;
>> unsigned long __unused2;
>> };
>
> If that's too much of a hack, we could also change the default __kernel_mode_t
> in asm-generic/posix_types.h to unsigned short, which it is on all 32-bit architectures
> except mips and xtensa. For some reason, all 64 bit architechtures use unsigned
> int for mode_t, but I couldn't find out why. Glibc uses unsigned int externally.
Is it this final solution (that above) or we just change kernel_mode_t to short?
Michal
>
> Arnd <><
--
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
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