diff --git a/net/bridge/br.c b/net/bridge/br.c index 26e1616b2c9052038c6c2810303adaf7d9c48423..671d13c10f6f4ed8118fe31fcceb28d7cde6edf1 100644 --- a/net/bridge/br.c +++ b/net/bridge/br.c @@ -52,7 +52,7 @@ static int br_device_event(struct notifier_block *unused, unsigned long event, v switch (event) { case NETDEV_CHANGEMTU: - dev_set_mtu(br->dev, br_mtu(br)); + br_mtu_auto_adjust(br); break; case NETDEV_CHANGEADDR: diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c index 278fc999d3550f278acdd336233d9cf8b8d47062..e682a668ce57c9c0f5b4db62438a640f03d65b34 100644 --- a/net/bridge/br_device.c +++ b/net/bridge/br_device.c @@ -224,11 +224,11 @@ static void br_get_stats64(struct net_device *dev, static int br_change_mtu(struct net_device *dev, int new_mtu) { struct net_bridge *br = netdev_priv(dev); - if (new_mtu > br_mtu(br)) - return -EINVAL; dev->mtu = new_mtu; + /* this flag will be cleared if the MTU was automatically adjusted */ + br->mtu_set_by_user = true; #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) /* remember the MTU in the rtable for PMTU */ dst_metric_set(&br->fake_rtable.dst, RTAX_MTU, new_mtu); diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c index 87b2afd455c7f7fa2e720672741e0dd2d85fe244..82c1a6f430b37d8fb9b4713ad7ab370a3ef5b990 100644 --- a/net/bridge/br_if.c +++ b/net/bridge/br_if.c @@ -424,41 +424,32 @@ int br_del_bridge(struct net *net, const char *name) return ret; } -static bool min_mtu(int a, int b) -{ - return a < b ? 1 : 0; -} - -static bool max_mtu(int a, int b) -{ - return a > b ? 1 : 0; -} - /* MTU of the bridge pseudo-device: ETH_DATA_LEN or the minimum of the ports */ -static int __br_mtu(const struct net_bridge *br, bool (compare_fn)(int, int)) +static int br_mtu_min(const struct net_bridge *br) { const struct net_bridge_port *p; - int mtu = 0; + int ret_mtu = 0; - ASSERT_RTNL(); + list_for_each_entry(p, &br->port_list, list) + if (!ret_mtu || ret_mtu > p->dev->mtu) + ret_mtu = p->dev->mtu; - if (list_empty(&br->port_list)) - mtu = ETH_DATA_LEN; - else { - list_for_each_entry(p, &br->port_list, list) { - if (!mtu || compare_fn(p->dev->mtu, mtu)) - mtu = p->dev->mtu; - } - } - return mtu; + return ret_mtu ? ret_mtu : ETH_DATA_LEN; } -int br_mtu(const struct net_bridge *br) +void br_mtu_auto_adjust(struct net_bridge *br) { - if (br_vlan_enabled(br->dev)) - return __br_mtu(br, max_mtu); - else - return __br_mtu(br, min_mtu); + ASSERT_RTNL(); + + /* if the bridge MTU was manually configured don't mess with it */ + if (br->mtu_set_by_user) + return; + + /* change to the minimum MTU and clear the flag which was set by + * the bridge ndo_change_mtu callback + */ + dev_set_mtu(br->dev, br_mtu_min(br)); + br->mtu_set_by_user = false; } static void br_set_gso_limits(struct net_bridge *br) @@ -612,7 +603,7 @@ int br_add_if(struct net_bridge *br, struct net_device *dev, if (changed_addr) call_netdevice_notifiers(NETDEV_CHANGEADDR, br->dev); - dev_set_mtu(br->dev, br_mtu(br)); + br_mtu_auto_adjust(br); br_set_gso_limits(br); kobject_uevent(&p->kobj, KOBJ_ADD); @@ -659,7 +650,7 @@ int br_del_if(struct net_bridge *br, struct net_device *dev) */ del_nbp(p); - dev_set_mtu(br->dev, br_mtu(br)); + br_mtu_auto_adjust(br); br_set_gso_limits(br); spin_lock_bh(&br->lock); diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h index 048d5b51813bac1e295c65b43d598d997892e95c..a7cb3ece5031092f9df529864affdfafdfd1cf28 100644 --- a/net/bridge/br_private.h +++ b/net/bridge/br_private.h @@ -410,6 +410,7 @@ struct net_bridge { int offload_fwd_mark; #endif bool neigh_suppress_enabled; + bool mtu_set_by_user; struct hlist_head fdb_list; }; @@ -578,7 +579,7 @@ int br_del_bridge(struct net *net, const char *name); int br_add_if(struct net_bridge *br, struct net_device *dev, struct netlink_ext_ack *extack); int br_del_if(struct net_bridge *br, struct net_device *dev); -int br_mtu(const struct net_bridge *br); +void br_mtu_auto_adjust(struct net_bridge *br); netdev_features_t br_features_recompute(struct net_bridge *br, netdev_features_t features); void br_port_flags_change(struct net_bridge_port *port, unsigned long mask);