bridge: use atomic ops to read/change p->flags in br_netlink.c

Change net/bridge/br_netlink.c to use atomic operations
to read/change bits in p->flags.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20260611203453.3067462-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 7cb24de9c77d3d15892723f77288c27a15a6a0ad..2178eb20475c36acc44890cc8384270d376febc3 100644 (file)
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -113,7 +113,7 @@ static size_t br_get_link_af_size_filtered(const struct net_device *dev,
        num_vlan_infos = br_get_num_vlan_infos(vg, filter_mask);
        rcu_read_unlock();
 
-       if (p && (p->flags & BR_VLAN_TUNNEL))
+       if (p && test_bit(BR_VLAN_TUNNEL_BIT, &p->flags))
                vinfo_sz += br_get_vlan_tunnel_info_size(vg);
 
        /* Each VLAN is returned in bridge_vlan_info along with flags */
@@ -823,7 +823,7 @@ static int br_afspec(struct net_bridge *br,
                err = 0;
                switch (nla_type(attr)) {
                case IFLA_BRIDGE_VLAN_TUNNEL_INFO:
-                       if (!p || !(p->flags & BR_VLAN_TUNNEL))
+                       if (!p || !test_bit(BR_VLAN_TUNNEL_BIT, &p->flags))
                                return -EINVAL;
                        err = br_parse_vlan_tunnel_info(attr, &tinfo_curr);
                        if (err)
@@ -934,58 +934,67 @@ static int br_set_port_state(struct net_bridge_port *p, u8 state)
 }
 
 /* Set/clear or port flags based on attribute */
-static void br_set_port_flag(struct net_bridge_port *p, struct nlattr *tb[],
+static void br_set_port_flag(unsigned long *set_flags,
+                            unsigned long *clear_flags,
+                            struct nlattr *tb[],
                             int attrtype, unsigned long mask)
 {
-       if (!tb[attrtype])
-               return;
-
-       if (nla_get_u8(tb[attrtype]))
-               p->flags |= mask;
-       else
-               p->flags &= ~mask;
+       if (tb[attrtype]) {
+               if (nla_get_u8(tb[attrtype]))
+                       *set_flags |= mask;
+               else
+                       *clear_flags |= mask;
+       }
 }
 
 /* Process bridge protocol info on port */
 static int br_setport(struct net_bridge_port *p, struct nlattr *tb[],
                      struct netlink_ext_ack *extack)
 {
-       unsigned long old_flags, changed_mask;
+       unsigned long old_flags, flags, changed_mask;
+       unsigned long set = 0, clear = 0;
        bool br_vlan_tunnel_old;
        int err;
 
-       old_flags = p->flags;
+       old_flags = READ_ONCE(p->flags);
        br_vlan_tunnel_old = (old_flags & BR_VLAN_TUNNEL) ? true : false;
 
-       br_set_port_flag(p, tb, IFLA_BRPORT_MODE, BR_HAIRPIN_MODE);
-       br_set_port_flag(p, tb, IFLA_BRPORT_GUARD, BR_BPDU_GUARD);
-       br_set_port_flag(p, tb, IFLA_BRPORT_FAST_LEAVE,
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_MODE, BR_HAIRPIN_MODE);
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_GUARD, BR_BPDU_GUARD);
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_FAST_LEAVE,
                         BR_MULTICAST_FAST_LEAVE);
-       br_set_port_flag(p, tb, IFLA_BRPORT_PROTECT, BR_ROOT_BLOCK);
-       br_set_port_flag(p, tb, IFLA_BRPORT_LEARNING, BR_LEARNING);
-       br_set_port_flag(p, tb, IFLA_BRPORT_UNICAST_FLOOD, BR_FLOOD);
-       br_set_port_flag(p, tb, IFLA_BRPORT_MCAST_FLOOD, BR_MCAST_FLOOD);
-       br_set_port_flag(p, tb, IFLA_BRPORT_MCAST_TO_UCAST,
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_PROTECT, BR_ROOT_BLOCK);
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_LEARNING, BR_LEARNING);
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_UNICAST_FLOOD, BR_FLOOD);
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_MCAST_FLOOD,
+                        BR_MCAST_FLOOD);
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_MCAST_TO_UCAST,
                         BR_MULTICAST_TO_UNICAST);
-       br_set_port_flag(p, tb, IFLA_BRPORT_BCAST_FLOOD, BR_BCAST_FLOOD);
-       br_set_port_flag(p, tb, IFLA_BRPORT_PROXYARP, BR_PROXYARP);
-       br_set_port_flag(p, tb, IFLA_BRPORT_PROXYARP_WIFI, BR_PROXYARP_WIFI);
-       br_set_port_flag(p, tb, IFLA_BRPORT_VLAN_TUNNEL, BR_VLAN_TUNNEL);
-       br_set_port_flag(p, tb, IFLA_BRPORT_NEIGH_SUPPRESS, BR_NEIGH_SUPPRESS);
-       br_set_port_flag(p, tb, IFLA_BRPORT_ISOLATED, BR_ISOLATED);
-       br_set_port_flag(p, tb, IFLA_BRPORT_LOCKED, BR_PORT_LOCKED);
-       br_set_port_flag(p, tb, IFLA_BRPORT_MAB, BR_PORT_MAB);
-       br_set_port_flag(p, tb, IFLA_BRPORT_NEIGH_VLAN_SUPPRESS,
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_BCAST_FLOOD,
+                        BR_BCAST_FLOOD);
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_PROXYARP, BR_PROXYARP);
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_PROXYARP_WIFI,
+                        BR_PROXYARP_WIFI);
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_VLAN_TUNNEL,
+                        BR_VLAN_TUNNEL);
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_NEIGH_SUPPRESS,
+                        BR_NEIGH_SUPPRESS);
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_ISOLATED, BR_ISOLATED);
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_LOCKED, BR_PORT_LOCKED);
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_MAB, BR_PORT_MAB);
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_NEIGH_VLAN_SUPPRESS,
                         BR_NEIGH_VLAN_SUPPRESS);
-       br_set_port_flag(p, tb, IFLA_BRPORT_NEIGH_FORWARD_GRAT,
+       br_set_port_flag(&set, &clear, tb, IFLA_BRPORT_NEIGH_FORWARD_GRAT,
                         BR_NEIGH_FORWARD_GRAT);
 
-       if ((p->flags & BR_PORT_MAB) &&
-           (!(p->flags & BR_PORT_LOCKED) || !(p->flags & BR_LEARNING))) {
+       flags = (old_flags | set) & ~clear;
+
+       if ((flags & BR_PORT_MAB) &&
+           (!(flags & BR_PORT_LOCKED) || !(flags & BR_LEARNING))) {
                NL_SET_ERR_MSG(extack, "Bridge port must be locked and have learning enabled when MAB is enabled");
-               p->flags = old_flags;
                return -EINVAL;
-       } else if (!(p->flags & BR_PORT_MAB) && (old_flags & BR_PORT_MAB)) {
+       }
+       if (!(flags & BR_PORT_MAB) && (old_flags & BR_PORT_MAB)) {
                struct net_bridge_fdb_flush_desc desc = {
                        .flags = BIT(BR_FDB_LOCKED),
                        .flags_mask = BIT(BR_FDB_LOCKED),
@@ -995,15 +1004,17 @@ static int br_setport(struct net_bridge_port *p, struct nlattr *tb[],
                br_fdb_flush(p->br, &desc);
        }
 
-       changed_mask = old_flags ^ p->flags;
+       changed_mask = old_flags ^ flags;
 
-       err = br_switchdev_set_port_flag(p, p->flags, changed_mask, extack);
-       if (err) {
-               p->flags = old_flags;
+       err = br_switchdev_set_port_flag(p, flags, changed_mask, extack);
+       if (err)
                return err;
-       }
 
-       if (br_vlan_tunnel_old && !(p->flags & BR_VLAN_TUNNEL))
+       do {
+               flags = (old_flags | set) & ~clear;
+       } while (!try_cmpxchg(&p->flags, &old_flags, flags));
+
+       if (br_vlan_tunnel_old && !(flags & BR_VLAN_TUNNEL))
                nbp_vlan_tunnel_info_flush(p);
 
        br_port_flags_change(p, changed_mask);