diff options
| author | Yuyang Huang <sigefriedhyy@gmail.com> | 2026-06-30 20:02:05 +0900 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2026-07-03 08:50:43 +0200 |
| commit | 7cb8198761e627ff3a3b4770c8f147e75c4e649d (patch) | |
| tree | 4063785da6cad89f956937db40aff0debbd3545b | |
| parent | 2ed8d5c72488bca9666fefa942ed2dc07cc0c56a (diff) | |
net: ipv4: report multicast group user count
RTM_GETMULTICAST has been part of the rtnetlink ABI for a long time
and already reports IPv4 multicast group membership through
IFA_MULTICAST and IFA_CACHEINFO. It does not report how many consumers
hold each membership, so userspace still has to parse /proc/net/igmp to
get the Users column.
Add IFA_MC_USERS as a u32 attribute carrying ip_mc_list::users in
RTM_GETMULTICAST replies and entry-lifecycle notifications.
This gives iproute2 enough information to migrate the IPv4 part of
"ip maddr show" from procfs parsing to rtnetlink.
Signed-off-by: Yuyang Huang <sigefriedhyy@gmail.com>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260630110207.37841-2-sigefriedhyy@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
| -rw-r--r-- | Documentation/netlink/specs/rt-addr.yaml | 4 | ||||
| -rw-r--r-- | include/uapi/linux/if_addr.h | 1 | ||||
| -rw-r--r-- | net/ipv4/igmp.c | 2 |
3 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/netlink/specs/rt-addr.yaml b/Documentation/netlink/specs/rt-addr.yaml index 163a106c41bb..0ecbd24c890c 100644 --- a/Documentation/netlink/specs/rt-addr.yaml +++ b/Documentation/netlink/specs/rt-addr.yaml @@ -123,6 +123,9 @@ attribute-sets: - name: proto type: u8 + - + name: mc-users + type: u32 operations: @@ -176,6 +179,7 @@ operations: value: 58 attributes: &mcaddr-attrs - multicast + - mc-users - cacheinfo dump: request: diff --git a/include/uapi/linux/if_addr.h b/include/uapi/linux/if_addr.h index aa7958b4e41d..7fb630b7fe31 100644 --- a/include/uapi/linux/if_addr.h +++ b/include/uapi/linux/if_addr.h @@ -36,6 +36,7 @@ enum { IFA_RT_PRIORITY, /* u32, priority/metric for prefix route */ IFA_TARGET_NETNSID, IFA_PROTO, /* u8, address protocol */ + IFA_MC_USERS, /* u32, multicast group users */ __IFA_MAX, }; diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index b6337a47c141..116ce7cec80e 100644 --- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -1473,6 +1473,7 @@ int inet_fill_ifmcaddr(struct sk_buff *skb, struct net_device *dev, ci.ifa_valid = INFINITY_LIFE_TIME; if (nla_put_in_addr(skb, IFA_MULTICAST, im->multiaddr) < 0 || + nla_put_u32(skb, IFA_MC_USERS, READ_ONCE(im->users)) < 0 || nla_put(skb, IFA_CACHEINFO, sizeof(ci), &ci) < 0) { nlmsg_cancel(skb, nlh); return -EMSGSIZE; @@ -1494,6 +1495,7 @@ static void inet_ifmcaddr_notify(struct net_device *dev, skb = nlmsg_new(NLMSG_ALIGN(sizeof(struct ifaddrmsg)) + nla_total_size(sizeof(__be32)) + + nla_total_size(sizeof(u32)) + nla_total_size(sizeof(struct ifa_cacheinfo)), GFP_KERNEL); if (!skb) |