David Laight wrote:
> On Tue, Jun 07, 2005 at 10:38:20AM -0700, Matt Thomas wrote:
> 
>>>Yes. The MD syscall code checks for the SYSCALL_MPSAFE flag and
>>>doesn't take the big-lock if it's set. It's currently only set for
>>>getpid(). Exactly what else it could be easily applied to is less
>>>clear; getpid() is the only true no-brainer that requires taking no
>>>locks on anything at all.
>>
>>get*gid?
>>get*uid?
> 
> 
> While another thread is doing set*[gu]id ?

Unless your process is taking care to do mutexes to control
ordering, the result you get back will be unpredictable (did
the set* run before or after the get*).  So you can treat
them as unlocked since the user code has to have some method
of serialization to get a meaningful answer.

-- 
Matt Thomas                     email: matt@3am-software.com
3am Software Foundry              www: http://3am-software.com/bio/matt/
Cupertino, CA              disclaimer: I avow all knowledge of this message.