On Fri, Jul 3, 2026 at 3:50 PM Paolo Abeni [off-list ref] wrote:

On 6/30/26 1:02 PM, Yuyang Huang wrote:

quoted

RTM_GETMULTICAST reports IPv4 and IPv6 multicast group membership, but
does not include the per-group user count. Userspace therefore still has
to parse /proc/net/igmp and /proc/net/igmp6 to obtain the Users column.
In particular, this prevents iproute2 from moving "ip maddr show"
entirely from procfs to rtnetlink.

Add IFA_MC_USERS to carry the user count in RTM_GETMULTICAST dumps and
RTM_NEWMULTICAST / RTM_DELMULTICAST notifications for both address
families. Update the rt-addr YNL specification and extend the rtnetlink
selftest to verify that two joins increase the reported count by two.

Will you take care of implementing the iproute2 bits, too?

Yes, I actually have something WIP for iproute2 and realized it cannot
be done due to the missing fields. That's why I sent out this patch
series first.