On Mon, Mar 02, 2026 at 06:40:07AM +0100, Linus Lüssing wrote:
> As the multicast active state variable is now always up to date and
> functionally equivalent to our manual, extensive checks in fast path
> we can just use this state variable in fast path, too. This allows to
> save some CPU cycles for every multicast packet in the fast/data path.
>
> Next to using brmctx->ip4_active / brmctx->ip6_active in fast path this
> mostly just moves some code around to not expose it via br_private.h
> anymore. While at it now also passing the ethernet protocol number
> directly, instead of a pointer into the ethernet header.
>
> Signed-off-by: Linus Lüssing <[email protected]>
> ---
> net/bridge/br_device.c | 3 ++-
> net/bridge/br_input.c | 3 ++-
> net/bridge/br_multicast.c | 41 ++++++++++++++++++++++++++++++++++-----
> net/bridge/br_private.h | 38 ++++++++----------------------------
> 4 files changed, 48 insertions(+), 37 deletions(-)
>
> diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
> index ee01122f466f..1ac363826b4c 100644
> --- a/net/bridge/br_device.c
> +++ b/net/bridge/br_device.c
> @@ -102,7 +102,8 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct
> net_device *dev)
>
> mdst = br_mdb_entry_skb_get(brmctx, skb, vid);
> if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
> - br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst))
> + br_multicast_snooping_active(brmctx, eth_hdr(skb)->h_proto,
> + mdst))
> br_multicast_flood(mdst, skb, brmctx, false, true);
> else
> br_flood(br, skb, BR_PKT_MULTICAST, false, true, vid);
> diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
> index 1405f1061a54..e79963e3d05f 100644
> --- a/net/bridge/br_input.c
> +++ b/net/bridge/br_input.c
> @@ -187,7 +187,8 @@ int br_handle_frame_finish(struct net *net, struct sock
> *sk, struct sk_buff *skb
> case BR_PKT_MULTICAST:
> mdst = br_mdb_entry_skb_get(brmctx, skb, vid);
> if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
> - br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) {
> + br_multicast_snooping_active(brmctx, eth_hdr(skb)->h_proto,
> + mdst)) {
> if ((mdst && mdst->host_joined) ||
> br_multicast_is_router(brmctx, skb) ||
> br->dev->flags & IFF_ALLMULTI) {
> diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
> index 715a0e0aa5ad..4a1005bb68f1 100644
> --- a/net/bridge/br_multicast.c
> +++ b/net/bridge/br_multicast.c
> @@ -1067,6 +1067,26 @@ static struct sk_buff
> *br_ip4_multicast_alloc_query(struct net_bridge_mcast *brm
> return skb;
> }
>
> +static bool
> +__br_multicast_querier_exists(struct net_bridge_mcast *brmctx,
> + struct bridge_mcast_other_query *querier,
> + bool is_ipv6)
> +{
> + bool own_querier_enabled;
> +
> + if (brmctx->multicast_querier) {
> + if (is_ipv6 && !br_opt_get(brmctx->br, BROPT_HAS_IPV6_ADDR))
> + own_querier_enabled = false;
> + else
> + own_querier_enabled = true;
> + } else {
> + own_querier_enabled = false;
> + }
> +
> + return !timer_pending(&querier->delay_timer) &&
> + (own_querier_enabled || timer_pending(&querier->timer));
> +}
> +
> static bool br_ip4_multicast_querier_exists(struct net_bridge_mcast *brmctx)
> {
> return __br_multicast_querier_exists(brmctx, &brmctx->ip4_other_query,
> false);
> @@ -1079,6 +1099,21 @@ static bool br_ip6_multicast_querier_exists(struct
> net_bridge_mcast *brmctx)
> }
> #endif
>
> +static bool
> +br_multicast_querier_exists(struct net_bridge_mcast *brmctx, u16 proto)
> +{
> + switch (proto) {
> + case ETH_P_IP:
> + return br_ip4_multicast_querier_exists(brmctx);
> +#if IS_ENABLED(CONFIG_IPV6)
> + case ETH_P_IPV6:
> + return br_ip6_multicast_querier_exists(brmctx);
> +#endif
> + default:
> + return false;
> + }
> +}
> +
> static void br_ip4_multicast_update_active(struct net_bridge_mcast *brmctx,
> bool force_inactive)
> {
> @@ -5132,7 +5167,6 @@ bool br_multicast_has_querier_anywhere(struct
> net_device *dev, int proto)
> {
> struct net_bridge *br;
> struct net_bridge_port *port;
> - struct ethhdr eth;
> bool ret = false;
>
> rcu_read_lock();
> @@ -5145,10 +5179,7 @@ bool br_multicast_has_querier_anywhere(struct
> net_device *dev, int proto)
>
> br = port->br;
>
> - memset(ð, 0, sizeof(eth));
> - eth.h_proto = htons(proto);
> -
> - ret = br_multicast_querier_exists(&br->multicast_ctx, ð, NULL);
> + ret = br_multicast_querier_exists(&br->multicast_ctx, proto);
>
> unlock:
> rcu_read_unlock();
> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
> index 8150ecc2c919..75684f8079f2 100644
> --- a/net/bridge/br_private.h
> +++ b/net/bridge/br_private.h
> @@ -1159,37 +1159,15 @@ br_multicast_is_router(struct net_bridge_mcast
> *brmctx, struct sk_buff *skb)
> }
>
> static inline bool
> -__br_multicast_querier_exists(struct net_bridge_mcast *brmctx,
> - struct bridge_mcast_other_query *querier,
> - const bool is_ipv6)
> +br_multicast_snooping_active(struct net_bridge_mcast *brmctx, __be16
> eth_proto,
const brmctx
> + const struct net_bridge_mdb_entry *mdb)
> {
> - bool own_querier_enabled;
> -
> - if (brmctx->multicast_querier) {
> - if (is_ipv6 && !br_opt_get(brmctx->br, BROPT_HAS_IPV6_ADDR))
> - own_querier_enabled = false;
> - else
> - own_querier_enabled = true;
> - } else {
> - own_querier_enabled = false;
> - }
> -
> - return !timer_pending(&querier->delay_timer) &&
> - (own_querier_enabled || timer_pending(&querier->timer));
> -}
> -
> -static inline bool br_multicast_querier_exists(struct net_bridge_mcast
> *brmctx,
> - struct ethhdr *eth,
> - const struct
> net_bridge_mdb_entry *mdb)
> -{
> - switch (eth->h_proto) {
> + switch (eth_proto) {
> case (htons(ETH_P_IP)):
since you're changing it, could you please remove the extra ()?
they're unnecessary and don't help readability
> - return __br_multicast_querier_exists(brmctx,
> - &brmctx->ip4_other_query, false);
> + return READ_ONCE(brmctx->ip4_active);
> #if IS_ENABLED(CONFIG_IPV6)
> case (htons(ETH_P_IPV6)):
> - return __br_multicast_querier_exists(brmctx,
> - &brmctx->ip6_other_query, true);
> + return READ_ONCE(brmctx->ip6_active);
> #endif
> default:
> return !!mdb && br_group_is_l2(&mdb->addr);
> @@ -1448,9 +1426,9 @@ static inline bool br_multicast_is_router(struct
> net_bridge_mcast *brmctx,
> return false;
> }
>
> -static inline bool br_multicast_querier_exists(struct net_bridge_mcast
> *brmctx,
> - struct ethhdr *eth,
> - const struct
> net_bridge_mdb_entry *mdb)
> +static inline bool
> +br_multicast_snooping_active(struct net_bridge_mcast *brmctx, __be16
> eth_proto,
> + const struct net_bridge_mdb_entry *mdb)
> {
> return false;
> }
> --
> 2.51.0
>
