Re: [PATCH] Fix argument checking in sched_setaffinity

[Paul Jackson <pj@sgi.com>]

Linus wrote:
> It's not. If anything, we should probably remove even more.
>
> I don't see what the problem was with just requiring the right damn size.  
> User mode can trivially get the size by asking for it

I'll second that motion.  Match size, or return -EINVAL.

My understanding of "asking for it" requires at present a user code
loop, to probe for the size that works.  But my user code already does
that, and the first thing for which I audit any changes to this kernel
code is not breaking my sizing loop code in user space.

I'd mildly prefer adding a kernel/user API for explicitly providing the
two values:

	sizeof(cpumask_t)
	sizeof(nodemask_t)

This might help reduce the unending confusions in the user and library
code sitting on top of us.

We could two phase this:
 1) add an obvious way to size these masks, and then
 2) six months later, require sizes to match in all these calls.

I for one could live with a full and sudden change over, no phasing.
But apparently my field exposure is more limited than Andi's is, at
this time.

-- 
                          I won't rest till it's the best ...
                          Programmer, Linux Scalability
                          Paul Jackson <pj@sgi.com> 1.650.933.1373