Re: [PATCH net-next v2] ppp: add IFLA_PPP_UNIT netlink attribute

[Pali Rohár]

On Wednesday 18 March 2026 09:59:29 Qingfang Deng wrote:
> On Sat, 14 Mar 2026 02:14:29 +0100, Martin Olivier wrote:
> > Currently, the PPP rtnetlink API allows creating a new network interface
> > with a custom ifname, but it lacks the ability to specify a custom PPP
> > unit id.
> > 
> > Setting a specific unit id is currently only possible with the
> > PPPIOCNEWUNIT ioctl. If a user-space program also requires a custom
> > interface name, it must create the interface first with PPPIOCNEWUNIT
> > and then rename it.
> > 
> > Resolve this by introducing the IFLA_PPP_UNIT netlink attribute. This
> > allows user-space programs to atomically request both a custom ifname
> > and a specific PPP unit id during the RTM_NEWLINK creation process,
> > eliminating the post-creation renaming for this use case.
> > 
> > Signed-off-by: Martin Olivier <martin.olivier@xxxxxxx>
> > ---
> > Changes in v2:
> > - use nl policy to set IFLA_PPP_UNIT min allowed value instead of a manual check in ppp_nl_validate()
> > - use of nla_get_s32_default() to collect IFLA_PPP_UNIT value
> > Link to v1: https://lore.kernel.org/netdev/PAWP192MB2411A5E7D3BE1B55E155A92F9747A@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
> 
> The patch itself looks good to me, but I would like to check the
> userspace changes too. Please create a pull request at
> https://github.com/ppp-project/ppp/pulls
> 
> +Cc: Paul Mackerras, Guillaume Nault, Pali Rohár
> 
> Regards,
> Qingfang

Hello Martin, in past I have sent similar change:
https://lore.kernel.org/linux-ppp/20210807163749.18316-1-pali@xxxxxxxxxx/T/#u
Look at the discussion, it can be useful to understand why the change
was not accepted.