Re: [PATCH net-next 5/7] phonet: pep: convert getsockopt to sockopt_t

[Breno Leitao]

On Fri, Jul 17, 2026 at 09:22:58AM +0100, David Laight wrote:

> > -	len = min_t(unsigned int, sizeof(int), len);
> > -	if (put_user(len, optlen))
> > +	len = min_t(unsigned int, sizeof(int), opt->optlen);
> 
> I'm pretty sure that can be min().

Right. opt->optlen is a plain int and sizeof(int) is a non-negative
constant, so min() takes it fine.

I'll switch it to min() in v2, thanks for the review.

> More generally I'm not at all sure about negative lengths.
> Historically the user type would have been 'int', but it got replaced
> by socklen_t which is probably unsigned.
> (IIRC one of the 64bit Unix had started using a 64bit type but I think
> it was sun objected to making that change so socklen_t was born.)

That's now handled one level up, in sockopt_init_user():

        if (get_user(len, optlen))
                return -EFAULT;
        if (len < 0)
                return -EINVAL;

> Also truncating below 4 bytes makes no sense here on BE systems.

Sure, but this is pre-existing, isn't it?

> Some code will try to write the significant bytes out, but that
> would be better done in the wrapper.

This is the transitional shim. The ->getsockopt prototype is shared by
every proto:

        int (*getsockopt)(struct sock *sk, int level, int optname,
                          char __user *optval, int __user *optlen);

So it can't take a sockopt_t until every leaf is converted.

Each converted leaf keeps the __user signature, builds the sockopt_t
itself and calls a do_*_getsockopt(sk, optname, sockopt_t *) helper.
Once all the getsockopt leaves are done, sockopt_init_user() moves into
the common caller, the prototype flips to sockopt_t *, and these
per-leaf wrappers are deleted. The full plan is in the phase-1 cover
letter:

https://lore.kernel.org/all/20260401-getsockopt-v2-0-611df6771aff@xxxxxxxxxx/

Thanks for the review,
--breno