Re: [v10][PATCH 8/9] Define clone_with_pids() syscall

[Dave Hansen <dave-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

On Sun, 2009-11-01 at 12:45 -0800, Sukadev Bhattiprolu wrote:
> +int sys_clone_with_pids(struct pt_regs *regs)
> +{
...
> +       rc = copy_from_user(&kcs, ucs, sizeof(kcs));
> +       if (rc)
> +               return -EFAULT;
> +
> +       /*
> +        * TODO: If size of clone_args is not what the kernel expects, it
> +        *       could be that kernel is newer and has an extended structure.
> +        *       When that happens, this check needs to be smarter (and we
> +        *       need an additional copy_from_user()). For now, assume exact
> +        *       match.
> +        */
> +       if (kcs.clone_args_size != sizeof(kcs))
> +               return -EINVAL;
> +
> +       /*
> +        * To avoid future compatibility issues, ensure unused fields are 0.
> +        */
> +       if (kcs.reserved1 || kcs.clone_flags_high)
> +               return -EINVAL;

Suka, is there a reason we don't have these bits in some
arch-independent code?  I would have thought the stuff in the
process_32.c code would be just as thin a wrapper as possible to unwrap
the pt_regs and call into generic code.

-- Dave