diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index 78beaa765c733..9f6add96de2d7 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -42,6 +42,7 @@ #include #include #include +#include struct user_namespace; struct proc_dir_entry; @@ -69,7 +70,7 @@ struct net { atomic_t dev_unreg_count; unsigned int dev_base_seq; /* protected by rtnl_mutex */ - int ifindex; + u32 ifindex; spinlock_t nsid_lock; atomic_t fnhe_genid; @@ -110,6 +111,7 @@ struct net { struct hlist_head *dev_name_head; struct hlist_head *dev_index_head; + struct xarray dev_by_index; struct raw_notifier_head netdev_chain; /* Note that @hash_mix can be read millions times per second, diff --git a/net/core/dev.c b/net/core/dev.c index e7ffcfa037f79..b58674774a57b 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -388,6 +388,8 @@ static void list_netdevice(struct net_device *dev) hlist_add_head_rcu(&dev->index_hlist, dev_index_hash(net, dev->ifindex)); write_unlock(&dev_base_lock); + /* We reserved the ifindex, this can't fail */ + WARN_ON(xa_store(&net->dev_by_index, dev->ifindex, dev, GFP_KERNEL)); dev_base_seq_inc(net); } @@ -397,8 +399,12 @@ static void list_netdevice(struct net_device *dev) */ static void unlist_netdevice(struct net_device *dev, bool lock) { + struct net *net = dev_net(dev); + ASSERT_RTNL(); + xa_erase(&net->dev_by_index, dev->ifindex); + /* Unlink dev from the device chain */ if (lock) write_lock(&dev_base_lock); @@ -9565,23 +9571,35 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack, } /** - * dev_new_index - allocate an ifindex - * @net: the applicable net namespace + * dev_index_reserve() - allocate an ifindex in a namespace + * @net: the applicable net namespace + * @ifindex: requested ifindex, pass %0 to get one allocated + * + * Allocate a ifindex for a new device. Caller must either use the ifindex + * to store the device (via list_netdevice()) or call dev_index_release() + * to give the index up. * - * Returns a suitable unique value for a new device interface - * number. The caller must hold the rtnl semaphore or the - * dev_base_lock to be sure it remains unique. + * Return: a suitable unique value for a new device interface number or -errno. */ -static int dev_new_index(struct net *net) +static int dev_index_reserve(struct net *net, u32 ifindex) { - int ifindex = net->ifindex; + int err; - for (;;) { - if (++ifindex <= 0) - ifindex = 1; - if (!__dev_get_by_index(net, ifindex)) - return net->ifindex = ifindex; - } + if (!ifindex) + err = xa_alloc_cyclic(&net->dev_by_index, &ifindex, NULL, + xa_limit_31b, &net->ifindex, GFP_KERNEL); + else + err = xa_insert(&net->dev_by_index, ifindex, NULL, GFP_KERNEL); + if (err < 0) + return err; + + return ifindex; +} + +static void dev_index_release(struct net *net, int ifindex) +{ + /* Expect only unused indexes, unlist_netdevice() removes the used */ + WARN_ON(xa_erase(&net->dev_by_index, ifindex)); } /* Delayed registration/unregisteration */ @@ -10051,11 +10069,10 @@ int register_netdevice(struct net_device *dev) goto err_uninit; } - ret = -EBUSY; - if (!dev->ifindex) - dev->ifindex = dev_new_index(net); - else if (__dev_get_by_index(net, dev->ifindex)) + ret = dev_index_reserve(net, dev->ifindex); + if (ret < 0) goto err_uninit; + dev->ifindex = ret; /* Transfer changeable features to wanted_features and enable * software offloads (GSO and GRO). @@ -10102,7 +10119,7 @@ int register_netdevice(struct net_device *dev) ret = call_netdevice_notifiers(NETDEV_POST_INIT, dev); ret = notifier_to_errno(ret); if (ret) - goto err_uninit; + goto err_ifindex_release; ret = netdev_register_kobject(dev); write_lock(&dev_base_lock); @@ -10158,6 +10175,8 @@ int register_netdevice(struct net_device *dev) err_uninit_notify: call_netdevice_notifiers(NETDEV_PRE_UNINIT, dev); +err_ifindex_release: + dev_index_release(net, dev->ifindex); err_uninit: if (dev->netdev_ops->ndo_uninit) dev->netdev_ops->ndo_uninit(dev); @@ -11035,9 +11054,19 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net, } /* Check that new_ifindex isn't used yet. */ - err = -EBUSY; - if (new_ifindex && __dev_get_by_index(net, new_ifindex)) - goto out; + if (new_ifindex) { + err = dev_index_reserve(net, new_ifindex); + if (err < 0) + goto out; + } else { + /* If there is an ifindex conflict assign a new one */ + err = dev_index_reserve(net, dev->ifindex); + if (err == -EBUSY) + err = dev_index_reserve(net, 0); + if (err < 0) + goto out; + new_ifindex = err; + } /* * And now a mini version of register_netdevice unregister_netdevice. @@ -11065,13 +11094,6 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net, rcu_barrier(); new_nsid = peernet2id_alloc(dev_net(dev), net, GFP_KERNEL); - /* If there is an ifindex conflict assign a new one */ - if (!new_ifindex) { - if (__dev_get_by_index(net, dev->ifindex)) - new_ifindex = dev_new_index(net); - else - new_ifindex = dev->ifindex; - } rtmsg_ifinfo_newnet(RTM_DELLINK, dev, ~0U, GFP_KERNEL, &new_nsid, new_ifindex); @@ -11249,6 +11271,9 @@ static int __net_init netdev_init(struct net *net) if (net->dev_index_head == NULL) goto err_idx; + net->ifindex = 1; + xa_init_flags(&net->dev_by_index, XA_FLAGS_ALLOC); + RAW_INIT_NOTIFIER_HEAD(&net->netdev_chain); return 0; @@ -11346,6 +11371,7 @@ static void __net_exit netdev_exit(struct net *net) { kfree(net->dev_name_head); kfree(net->dev_index_head); + xa_destroy(&net->dev_by_index); if (net != &init_net) WARN_ON_ONCE(!list_empty(&net->dev_base_head)); }