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vxlan: Add RCU read-side critical sections in the Tx path

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The Tx path does not run from an RCU read-side critical section which
makes the current lockless accesses to FDB entries invalid. As far as I
am aware, this has not been a problem in practice, but traces will be
generated once we transition the FDB lookup to rhashtable_lookup().

Add rcu_read_{lock,unlock}() around the handling of FDB entries in the
Tx path. Remove the RCU read-side critical section from vxlan_xmit_nh()
as now the function is always called from an RCU read-side critical
section.

Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20250415121143.345227-2-idosch@nvidia.com
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Ido Schimmel 2025-04-15 15:11:29 +03:00 committed by Paolo Abeni
parent 07e32237ed
commit 804b09be09
1 changed files with 8 additions and 6 deletions
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14
drivers/net/vxlan/vxlan_core.c
View File

@ -1916,12 +1916,15 @@ static int arp_reduce(struct net_device *dev, struct sk_buff *skb, __be32 vni)
goto out;
}
rcu_read_lock();
f = vxlan_find_mac(vxlan, n->ha, vni);
if (f && vxlan_addr_any(&(first_remote_rcu(f)->remote_ip))) {
/* bridge-local neighbor */
neigh_release(n);
rcu_read_unlock();
goto out;
}
rcu_read_unlock();
reply = arp_create(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha,
n->ha, sha);
@ -2648,14 +2651,10 @@ static void vxlan_xmit_nh(struct sk_buff *skb, struct net_device *dev,
memset(&nh_rdst, 0, sizeof(struct vxlan_rdst));
hash = skb_get_hash(skb);
rcu_read_lock();
nh = rcu_dereference(f->nh);
if (!nh) {
rcu_read_unlock();
if (!nh)
goto drop;
}
do_xmit = vxlan_fdb_nh_path_select(nh, hash, &nh_rdst);
rcu_read_unlock();
if (likely(do_xmit))
vxlan_xmit_one(skb, dev, vni, &nh_rdst, did_rsc);
@ -2782,6 +2781,7 @@ static netdev_tx_t vxlan_xmit(struct sk_buff *skb, struct net_device *dev)
}
eth = eth_hdr(skb);
rcu_read_lock();
f = vxlan_find_mac(vxlan, eth->h_dest, vni);
did_rsc = false;
@ -2804,7 +2804,7 @@ static netdev_tx_t vxlan_xmit(struct sk_buff *skb, struct net_device *dev)
vxlan_vnifilter_count(vxlan, vni, NULL,
VXLAN_VNI_STATS_TX_DROPS, 0);
kfree_skb_reason(skb, SKB_DROP_REASON_NO_TX_TARGET);
return NETDEV_TX_OK;
goto out;
}
}
@ -2829,6 +2829,8 @@ static netdev_tx_t vxlan_xmit(struct sk_buff *skb, struct net_device *dev)
kfree_skb_reason(skb, SKB_DROP_REASON_NO_TX_TARGET);
}
out:
rcu_read_unlock();
return NETDEV_TX_OK;
}