Re: [PATCH] Use __syscall_ulong_t for __cpu_mask

["Carlos O'Donell" <carlos at redhat dot com>]

On 12/01/2015 11:10 AM, H.J. Lu wrote:
> On Tue, Dec 1, 2015 at 8:07 AM, Carlos O'Donell <carlos@redhat.com> wrote:
>> On 11/30/2015 01:46 PM, H.J. Lu wrote:
>>> Since x86-64 and x32 use the same set of sched_XXX system call
>>> interface:
>>>
>>> [hjl@gnu-6 linux-stable]$ grep sched_
>>> arch/x86/entry/syscalls/syscall_64.tbl
>>> 24    common  sched_yield             sys_sched_yield
>>> 142   common  sched_setparam          sys_sched_setparam
>>> 143   common  sched_getparam          sys_sched_getparam
>>> 144   common  sched_setscheduler      sys_sched_setscheduler
>>> 145   common  sched_getscheduler      sys_sched_getscheduler
>>> 146   common  sched_get_priority_max  sys_sched_get_priority_max
>>> 147   common  sched_get_priority_min  sys_sched_get_priority_min
>>> 148   common  sched_rr_get_interval   sys_sched_rr_get_interval
>>> 203   common  sched_setaffinity       sys_sched_setaffinity
>>> 204   common  sched_getaffinity       sys_sched_getaffinity
>>> 314   common  sched_setattr           sys_sched_setattr
>>> 315   common  sched_getattr           sys_sched_getattr
>>> [hjl@gnu-6 linux-stable]$
>>>
>>> __cpu_mask should be __syscall_ulong_t.
>>>
>>>       [BZ #19313]
>>>       * sysdeps/unix/sysv/linux/bits/sched.h (__cpu_mask): Replace
>>>       unsigned long int with __syscall_ulong_t.
>>
>> How did you test this?
> 
> I tested it on x32, i686 and x86-64.  Maybe we should add
> __CPU_MASK_TYPE to bits/typesizes.h so that each
> architecture can define it own type for __cpu_mask.

The definition of __syscall_ulong_t, AFAICT, is always
`unsigned long int`, which means the change does nothing?
Aren't both of these types the same size on x86_64 and
x32?

What exactly was the failure mode you saw in bug 19313?

Cheers,
Carlos.