* Re: ipc64_perm - generic [not found] <4A1AE972.9010905@monstr.eu> @ 2009-05-25 22:21 ` Arnd Bergmann 2009-05-26 5:47 ` Michal Simek 0 siblings, 1 reply; 2+ messages in thread From: Arnd Bergmann @ 2009-05-25 22:21 UTC (permalink / raw) To: monstr, linux-arch; +Cc: John Williams, linux-kernel, Arnd Bergmann 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. Arnd <>< ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: ipc64_perm - generic 2009-05-25 22:21 ` ipc64_perm - generic Arnd Bergmann @ 2009-05-26 5:47 ` Michal Simek 0 siblings, 0 replies; 2+ messages in thread From: Michal Simek @ 2009-05-26 5:47 UTC (permalink / raw) To: Arnd Bergmann; +Cc: linux-arch, John Williams, linux-kernel 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 ^ permalink raw reply [flat|nested] 2+ messages in thread
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2009-05-25 22:21 ` ipc64_perm - generic Arnd Bergmann
2009-05-26 5:47 ` Michal Simek
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