Re: [PATCH iproute2 1/5] iplink: Fix setting of -1 as ifindex

Cong Wang
2014-10-07T00:42:13Z

On Fri, Oct 3, 2014 at 8:55 AM, Tom Herbert <therbert@google.com> wrote:
> Commit 3c682146aeff157ec3540 ("iplink: forbid negative ifindex and
> modifying ifindex") initializes index to -1 in iplink_modify. When
> creating a link, req.i.ifi_index is then set to -1 if the link option is
> not used. In the kernel this is then used to set dev->ifindex. For
> dev->ifindex, zero is considered to be unset and -1 is treated as
> a set index, so when a second tunnel is create the new device conflicts
> with the old one (both have ifindex of -1) so -EBUSY is returned.
>
> This patch set zero in req.i.ifi_index is index is unset (still -1).

There was a patch before yours: