Subject: Re: [RFC] separate SIOCGIFCONF from the rest of dev_ioctl()

From: Johannes Berg <[email-masked]>
Date: Mon, 26 Jun 2017 22:25:14 +0200

On Mon, 2017-06-26 at 18:40 +0100, Al Viro wrote:

> 	Only two of dev_ioctl() callers may pass SIOCGIFCONF to it.
> Separating that codepath from the rest of dev_ioctl() allows both
> to simplify dev_ioctl() itself (all other cases work with struct
> ifreq *)
> *and* seriously simplify the compat side of that beast: all it takes
> is passing to inet_gifconf() an extra argument - the size of
> individual
> records (sizeof(struct ifreq) or sizeof(struct compat_ifreq)).  With
> dev_ifconf() called directly from sock_do_ioctl()/compat_dev_ifconf()
> that's easy to arrange.

No objection from me; however, I just introduced another special case
(in a bugfix for a >20yo bug ...) here:

https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=68dd02d19c811ca8ea60220a9d73e13b4bdad73a

It would perhaps make sense to also pull that out into the caller,
which could also get rid of the stupid way the #ifdef is placed in
sock_ioctl(). For compat, it's already pulled out anyway, even a level
up than where you're calling it for SIOCGIFCONF - might make sense to
put the wext stuff into compat_sock_ioctl_trans() too.

johannes