[PATCH net-next 2/2] hsr: no longer rely on RTNL in hsr_fill_info()
From: Eric Dumazet <edumazet@google.com>
Date: 2026-09-16 13:28:28
Subsystem:
hsr network protocol, networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
hsr_fill_info() used hsr_port_get_hsr(), which walks hsr->ports with hsr_for_each_port_rtnl(), forcing "ip link show" dumps to hold RTNL. hsr->ports is an RCU protected list: ports are added with list_add_tail_rcu(), removed with list_del_rcu() and freed with kfree_rcu(), and the data path already iterates over it with hsr_for_each_port(). Add a local RCU variant of hsr_port_get_hsr() and use it from hsr_fill_info() under rcu_read_lock(). The remaining fields (sup_multicast_addr, prot_version) are set once at device creation. hsr->sequence_nr is now read with READ_ONCE(), since the transmit paths increment it under hsr->seqnr_lock only. Also add missing const qualifiers. Signed-off-by: Eric Dumazet <edumazet@google.com> --- net/hsr/hsr_netlink.c | 35 ++++++++++++++++++++++++++--------- 1 file changed, 26 insertions(+), 9 deletions(-)
diff --git a/net/hsr/hsr_netlink.c b/net/hsr/hsr_netlink.c
index 88940e8014b24f35d6a54f49fb7ac82956aed383..fc7820eae884132dbd5f4e62a4397d2c6d1bf79d 100644
--- a/net/hsr/hsr_netlink.c
+++ b/net/hsr/hsr_netlink.c@@ -147,44 +147,61 @@ static void hsr_dellink(struct net_device *dev, struct list_head *head) unregister_netdevice_queue(dev, head); } +/* RCU variant of hsr_port_get_hsr() */ +static struct hsr_port *hsr_port_get_hsr_rcu(const struct hsr_priv *hsr, + enum hsr_port_type pt) +{ + struct hsr_port *port; + + hsr_for_each_port(hsr, port) + if (port->type == pt) + return port; + return NULL; +} + static int hsr_fill_info(struct sk_buff *skb, const struct net_device *dev) { - struct hsr_priv *hsr = netdev_priv(dev); + const struct hsr_priv *hsr = netdev_priv(dev); + const struct hsr_port *port; u8 proto = HSR_PROTOCOL_HSR; - struct hsr_port *port; - port = hsr_port_get_hsr(hsr, HSR_PT_SLAVE_A); + rcu_read_lock(); + + port = hsr_port_get_hsr_rcu(hsr, HSR_PT_SLAVE_A); if (port) { if (nla_put_u32(skb, IFLA_HSR_SLAVE1, port->dev->ifindex)) goto nla_put_failure; } - port = hsr_port_get_hsr(hsr, HSR_PT_SLAVE_B); + port = hsr_port_get_hsr_rcu(hsr, HSR_PT_SLAVE_B); if (port) { if (nla_put_u32(skb, IFLA_HSR_SLAVE2, port->dev->ifindex)) goto nla_put_failure; } - port = hsr_port_get_hsr(hsr, HSR_PT_INTERLINK); + port = hsr_port_get_hsr_rcu(hsr, HSR_PT_INTERLINK); if (port) { if (nla_put_u32(skb, IFLA_HSR_INTERLINK, port->dev->ifindex)) goto nla_put_failure; } + rcu_read_unlock(); + if (nla_put(skb, IFLA_HSR_SUPERVISION_ADDR, ETH_ALEN, hsr->sup_multicast_addr) || - nla_put_u16(skb, IFLA_HSR_SEQ_NR, hsr->sequence_nr)) - goto nla_put_failure; + nla_put_u16(skb, IFLA_HSR_SEQ_NR, READ_ONCE(hsr->sequence_nr))) + return -EMSGSIZE; if (hsr->prot_version == PRP_V1) proto = HSR_PROTOCOL_PRP; else if (nla_put_u8(skb, IFLA_HSR_VERSION, hsr->prot_version)) - goto nla_put_failure; + return -EMSGSIZE; if (nla_put_u8(skb, IFLA_HSR_PROTOCOL, proto)) - goto nla_put_failure; + return -EMSGSIZE; return 0; nla_put_failure: + rcu_read_unlock(); return -EMSGSIZE; }
--
2.55.0.1032.g73a4cd73de-goog