Why use `thread' as an argument of Syscalls?

[Poul-Henning Kamp]

In message <448450FD.4030709 at FreeBSD.org>, Suleiman Souhlal writes:
>Robert Watson wrote:
>> 
>> On Mon, 5 Jun 2006, Daniel Eischen wrote:
>> 
>>>> They are the same questions, I think ;-). Now would you please 
>>>> explain "why use `proc' as an argument of Syscalls"  to me :)?  I've 
>>>> read some source code of the kernel, but no comments about it found.
>>>
>>>
>>> I don't know.  Convention?  It makes sense to me.
>> 
>> 
>> Certainly consistency.  Most system calls do actually use the argument 
>> at some point -- be it to look up a file descriptor, access control, or 
>> the like, and the calling context has it for free and in-hand anyway.
>
>But couldn't they just use curthread/curproc?

Yes, mostly.

It's a good question how much, if anything, it helps.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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