bridge: provide lockless access to p->designated_port

Add READ_ONCE()/WRITE_ONCE() annotations around p->designated_port

This is needed at least for sysfs show_designated_port(), BRCTL_GET_PORT_INFO
and upcoming RTNL avoidance in "ip link" dumps (cf br_port_fill_attrs()).

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20260604141343.2124500-8-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/bridge/br_ioctl.c b/net/bridge/br_ioctl.c
index a507c7b369ac49803019cdca7836c7fb9ef4459e..2be802991f70ab3ce48ade5da6d1488e072dbec6 100644 (file)
--- a/net/bridge/br_ioctl.c
+++ b/net/bridge/br_ioctl.c
@@ -258,7 +258,7 @@ int br_dev_siocdevprivate(struct net_device *dev, struct ifreq *rq,
                memcpy(&p.designated_root, &pt->designated_root, 8);
                memcpy(&p.designated_bridge, &pt->designated_bridge, 8);
                p.port_id = pt->port_id;
-               p.designated_port = pt->designated_port;
+               p.designated_port = READ_ONCE(pt->designated_port);
                p.path_cost = READ_ONCE(pt->path_cost);
                p.designated_cost = READ_ONCE(pt->designated_cost);
                p.state = pt->state;

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 296f62ebdd4a6f3d404b5902fe661995bd1ca0f5..a722db89aef6bbb6ecc77c7e0f173dc79418797f 100644 (file)
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -263,7 +263,8 @@ static int br_port_fill_attrs(struct sk_buff *skb,
                    &p->designated_root) ||
            nla_put(skb, IFLA_BRPORT_BRIDGE_ID, sizeof(struct ifla_bridge_id),
                    &p->designated_bridge) ||
-           nla_put_u16(skb, IFLA_BRPORT_DESIGNATED_PORT, p->designated_port) ||
+           nla_put_u16(skb, IFLA_BRPORT_DESIGNATED_PORT,
+                       READ_ONCE(p->designated_port)) ||
            nla_put_u16(skb, IFLA_BRPORT_DESIGNATED_COST,
                        READ_ONCE(p->designated_cost)) ||
            nla_put_u16(skb, IFLA_BRPORT_ID, p->port_id) ||

diff --git a/net/bridge/br_stp.c b/net/bridge/br_stp.c
index ced8d23f05d1ee262d1760c768e5c88868f13178..cbc48197c3db5e225ead7425b2cee46acc9768f3 100644 (file)
--- a/net/bridge/br_stp.c
+++ b/net/bridge/br_stp.c
@@ -261,7 +261,7 @@ static void br_record_config_information(struct net_bridge_port *p,
        p->designated_root = bpdu->root;
        WRITE_ONCE(p->designated_cost, bpdu->root_path_cost);
        p->designated_bridge = bpdu->bridge_id;
-       p->designated_port = bpdu->port_id;
+       WRITE_ONCE(p->designated_port, bpdu->port_id);
        p->designated_age = jiffies - bpdu->message_age;
 
        mod_timer(&p->message_age_timer, jiffies
@@ -434,7 +434,7 @@ void br_become_designated_port(struct net_bridge_port *p)
        p->designated_root = br->designated_root;
        WRITE_ONCE(p->designated_cost, br->root_path_cost);
        p->designated_bridge = br->bridge_id;
-       p->designated_port = p->port_id;
+       WRITE_ONCE(p->designated_port, p->port_id);
 }
 
 

diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
index e5d43492d2dcf0615ee984bc190d7ce2264aaab0..7b0d1a334785047905a00694fd65e3212b160e5d 100644 (file)
--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c
@@ -320,7 +320,7 @@ int br_stp_set_port_priority(struct net_bridge_port *p, unsigned long newprio)
 
        new_port_id = br_make_port_id(newprio, p->port_no);
        if (br_is_designated_port(p))
-               p->designated_port = new_port_id;
+               WRITE_ONCE(p->designated_port, new_port_id);
 
        p->port_id = new_port_id;
        p->priority = newprio;

diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c
index 36b832902d33a492e91d53a4248778b3ee2322ca..1023f97b1c9a22a1f79c3c734aef9bd41832ea39 100644 (file)
--- a/net/bridge/br_sysfs_if.c
+++ b/net/bridge/br_sysfs_if.c
@@ -129,7 +129,7 @@ static BRPORT_ATTR(designated_bridge, 0444, show_designated_bridge, NULL);
 
 static ssize_t show_designated_port(struct net_bridge_port *p, char *buf)
 {
-       return sysfs_emit(buf, "%d\n", p->designated_port);
+       return sysfs_emit(buf, "%d\n", READ_ONCE(p->designated_port));
 }
 static BRPORT_ATTR(designated_port, 0444, show_designated_port, NULL);