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net: bridge: fdb: avoid VLAN lookups in unicast forwarding

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Pass the complete fdb destination to br_forward(). The tagged value is
decoded once into br_fwd_dst on entry so all subsequent forwarding checks
use the decoded port and VLAN. A cached port-VLAN is then used to avoid two
VLAN hash lookups in the standard unicast forwarding path. A backup-port
redirect also uses a raw destination because the cached VLAN belongs to the
original port.

[1] 64 byte vlan packets, 4k randomized fdb hits with 4k fdbs, 5 million
    packets passed 5 times for every case
 VIDs  Ports       Mpps                 Gbps             CPU1 cycles/input
                before    after   gain  before   after   before   after  reduction
   64    8/2  2.375486 2.635811  11.0%   1.216   1.350   1724.6  1553.7    9.9%
   64    8/4  2.376731 2.636459  10.9%   1.217   1.350   1714.8  1554.7    9.3%
   64    8/8  2.376621 2.635783  10.9%   1.217   1.350   1722.6  1553.2    9.8%
   64   32/2  2.375876 2.637897  11.0%   1.216   1.351   1726.7  1552.3   10.1%
   64  32/16  2.376442 2.636426  10.9%   1.217   1.350   1721.3  1554.2    9.7%
   64  32/32  2.376763 2.636268  10.9%   1.217   1.350   1726.8  1553.5   10.0%
   64   64/2  2.375678 2.638707  11.1%   1.216   1.351   1725.0  1552.1   10.0%
   64  64/32  2.376681 2.637359  11.0%   1.217   1.350   1725.1  1555.9    9.8%
   64  64/64  2.376787 2.638396  11.0%   1.217   1.351   1722.8  1550.9   10.0%
 1024    8/2  2.263768 2.498881  10.4%   1.159   1.279   1808.5  1637.1    9.5%
 1024    8/4  2.264519 2.499075  10.4%   1.159   1.280   1807.6  1638.8    9.3%
 1024    8/8  2.263551 2.499231  10.4%   1.159   1.280   1812.0  1640.2    9.5%
 1024   32/2  2.263841 2.499120  10.4%   1.159   1.280   1806.8  1639.6    9.3%
 1024  32/16  2.263990 2.499562  10.4%   1.159   1.280   1806.1  1639.2    9.2%
 1024  32/32  2.263719 2.498905  10.4%   1.159   1.279   1807.7  1639.3    9.3%
 1024   64/2  2.263635 2.501889  10.5%   1.159   1.281   1809.4  1635.6    9.6%
 1024  64/32  2.264467 2.500359  10.4%   1.159   1.280   1806.5  1633.0    9.6%
 1024  64/64  2.240494 2.470246  10.3%   1.147   1.265   1810.0  1637.1    9.6%

Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20260930071411.2786201-13-razor@blackwall.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Nikolay Aleksandrov 2026-09-30 10:14:11 +03:00 committed by Jakub Kicinski
parent 8533e9b85b
commit f1829618e0
6 changed files with 23 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
net/bridge/br_device.c
View File

@ -108,7 +108,7 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
else
br_flood(br, vlan, skb, BR_PKT_MULTICAST, false, true);
} else if ((dst = br_fdb_find_rcu(br, dest, vid)) != NULL) {
br_forward(br_fdb_dst_port(dst), skb, false, true);
br_forward(br_fdb_dst_read(dst), skb, false, true);
} else {
br_flood(br, vlan, skb, BR_PKT_UNICAST, false, true);
}

24
net/bridge/br_forward.c
View File

@ -17,7 +17,7 @@
#include "br_private.h"
struct br_fwd_dst {
const struct net_bridge_port *port;
struct net_bridge_port *port;
struct net_bridge_vlan *vlan;
};
@ -149,35 +149,37 @@ static int deliver_clone(const struct br_fwd_dst *fwd,
/**
* br_forward - forward a packet to a specific port
* @to: destination port
* @dst: bridge destination
* @skb: packet being forwarded
* @local_rcv: packet will be received locally after forwarding
* @local_orig: packet is locally originated
*
* Should be called with rcu_read_lock.
*/
void br_forward(const struct net_bridge_port *to,
void br_forward(struct net_bridge_dst dst,
struct sk_buff *skb, bool local_rcv, bool local_orig)
{
struct br_fwd_dst fwd;
if (unlikely(!to))
br_dst_decode(dst, &fwd.port, &fwd.vlan);
if (unlikely(!fwd.port))
goto out;
/* redirect to backup link if the destination port is down */
if (rcu_access_pointer(to->backup_port) &&
(!netif_carrier_ok(to->dev) || !netif_running(to->dev))) {
if (rcu_access_pointer(fwd.port->backup_port) &&
(!netif_carrier_ok(fwd.port->dev) ||
!netif_running(fwd.port->dev))) {
struct net_bridge_port *backup_port;
backup_port = rcu_dereference(to->backup_port);
backup_port = rcu_dereference(fwd.port->backup_port);
if (unlikely(!backup_port))
goto out;
BR_INPUT_SKB_CB(skb)->backup_nhid = READ_ONCE(to->backup_nhid);
to = backup_port;
BR_INPUT_SKB_CB(skb)->backup_nhid = READ_ONCE(fwd.port->backup_nhid);
fwd.port = backup_port;
fwd.vlan = NULL;
}
fwd.port = to;
fwd.vlan = NULL;
if (should_deliver(&fwd, skb)) {
if (local_rcv)
deliver_clone(&fwd, skb, local_orig);

2
net/bridge/br_input.c
View File

@ -225,7 +225,7 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
if (now != READ_ONCE(dst->used))
WRITE_ONCE(dst->used, now);
br_forward(br_fdb_dst_port(dst), skb, local_rcv, false);
br_forward(br_fdb_dst_read(dst), skb, local_rcv, false);
} else {
if (!mcast_hit)
br_flood(br, vlan, skb, pkt_type, local_rcv, false);

6
net/bridge/br_mrp.c
View File

@ -1219,11 +1219,11 @@ static int br_mrp_rcv(struct net_bridge_port *p,
forward:
if (p_dst)
br_forward(p_dst, skb, true, false);
br_forward(br_port_to_dst(p_dst), skb, true, false);
if (s_dst)
br_forward(s_dst, skb, true, false);
br_forward(br_port_to_dst(s_dst), skb, true, false);
if (i_dst)
br_forward(i_dst, skb, true, false);
br_forward(br_port_to_dst(i_dst), skb, true, false);
no_forward:
return 1;

2
net/bridge/br_private.h
View File

@ -1045,7 +1045,7 @@ enum br_pkt_type {
BR_PKT_BROADCAST
};
int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb);
void br_forward(const struct net_bridge_port *to, struct sk_buff *skb,
void br_forward(struct net_bridge_dst dst, struct sk_buff *skb,
bool local_rcv, bool local_orig);
int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb);
void br_flood(struct net_bridge *br, struct net_bridge_vlan *v,

8
net/bridge/netfilter/nft_reject_bridge.c
View File

@ -55,7 +55,7 @@ static void nft_reject_br_send_v4_tcp_reset(struct net *net,
nft_reject_br_push_etherhdr(oldskb, nskb);
br_forward(br_port_get_rcu(dev), nskb, false, true);
br_forward(br_port_to_dst(br_port_get_rcu(dev)), nskb, false, true);
}
static void nft_reject_br_send_v4_unreach(struct net *net,
@ -71,7 +71,7 @@ static void nft_reject_br_send_v4_unreach(struct net *net,
nft_reject_br_push_etherhdr(oldskb, nskb);
br_forward(br_port_get_rcu(dev), nskb, false, true);
br_forward(br_port_to_dst(br_port_get_rcu(dev)), nskb, false, true);
}
static void nft_reject_br_send_v6_tcp_reset(struct net *net,
@ -87,7 +87,7 @@ static void nft_reject_br_send_v6_tcp_reset(struct net *net,
nft_reject_br_push_etherhdr(oldskb, nskb);
br_forward(br_port_get_rcu(dev), nskb, false, true);
br_forward(br_port_to_dst(br_port_get_rcu(dev)), nskb, false, true);
}
@ -104,7 +104,7 @@ static void nft_reject_br_send_v6_unreach(struct net *net,
nft_reject_br_push_etherhdr(oldskb, nskb);
br_forward(br_port_get_rcu(dev), nskb, false, true);
br_forward(br_port_to_dst(br_port_get_rcu(dev)), nskb, false, true);
}
static void nft_reject_bridge_eval(const struct nft_expr *expr,