1 files changed, 525 insertions, 0 deletions

diff --git a/net/sched/sch_teql.c b/net/sched/sch_teql.c
new file mode 100644
index 000000000..7721239c1
--- /dev/null
+++ b/net/sched/sch_teql.c
@@ -0,0 +1,525 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* net/sched/sch_teql.c	"True" (or "trivial") link equalizer.
+ *
+ * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/if_arp.h>
+#include <linux/netdevice.h>
+#include <linux/init.h>
+#include <linux/skbuff.h>
+#include <linux/moduleparam.h>
+#include <net/dst.h>
+#include <net/neighbour.h>
+#include <net/pkt_sched.h>
+
+/*
+   How to setup it.
+   ----------------
+
+   After loading this module you will find a new device teqlN
+   and new qdisc with the same name. To join a slave to the equalizer
+   you should just set this qdisc on a device f.e.
+
+   # tc qdisc add dev eth0 root teql0
+   # tc qdisc add dev eth1 root teql0
+
+   That's all. Full PnP 8)
+
+   Applicability.
+   --------------
+
+   1. Slave devices MUST be active devices, i.e., they must raise the tbusy
+      signal and generate EOI events. If you want to equalize virtual devices
+      like tunnels, use a normal eql device.
+   2. This device puts no limitations on physical slave characteristics
+      f.e. it will equalize 9600baud line and 100Mb ethernet perfectly :-)
+      Certainly, large difference in link speeds will make the resulting
+      eqalized link unusable, because of huge packet reordering.
+      I estimate an upper useful difference as ~10 times.
+   3. If the slave requires address resolution, only protocols using
+      neighbour cache (IPv4/IPv6) will work over the equalized link.
+      Other protocols are still allowed to use the slave device directly,
+      which will not break load balancing, though native slave
+      traffic will have the highest priority.  */
+
+struct teql_master {
+	struct Qdisc_ops qops;
+	struct net_device *dev;
+	struct Qdisc *slaves;
+	struct list_head master_list;
+	unsigned long	tx_bytes;
+	unsigned long	tx_packets;
+	unsigned long	tx_errors;
+	unsigned long	tx_dropped;
+};
+
+struct teql_sched_data {
+	struct Qdisc *next;
+	struct teql_master *m;
+	struct sk_buff_head q;
+};
+
+#define NEXT_SLAVE(q) (((struct teql_sched_data *)qdisc_priv(q))->next)
+
+#define FMASK (IFF_BROADCAST | IFF_POINTOPOINT)
+
+/* "teql*" qdisc routines */
+
+static int
+teql_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
+{
+	struct net_device *dev = qdisc_dev(sch);
+	struct teql_sched_data *q = qdisc_priv(sch);
+
+	if (q->q.qlen < dev->tx_queue_len) {
+		__skb_queue_tail(&q->q, skb);
+		return NET_XMIT_SUCCESS;
+	}
+
+	return qdisc_drop(skb, sch, to_free);
+}
+
+static struct sk_buff *
+teql_dequeue(struct Qdisc *sch)
+{
+	struct teql_sched_data *dat = qdisc_priv(sch);
+	struct netdev_queue *dat_queue;
+	struct sk_buff *skb;
+	struct Qdisc *q;
+
+	skb = __skb_dequeue(&dat->q);
+	dat_queue = netdev_get_tx_queue(dat->m->dev, 0);
+	q = rcu_dereference_bh(dat_queue->qdisc);
+
+	if (skb == NULL) {
+		struct net_device *m = qdisc_dev(q);
+		if (m) {
+			dat->m->slaves = sch;
+			netif_wake_queue(m);
+		}
+	} else {
+		qdisc_bstats_update(sch, skb);
+	}
+	sch->q.qlen = dat->q.qlen + q->q.qlen;
+	return skb;
+}
+
+static struct sk_buff *
+teql_peek(struct Qdisc *sch)
+{
+	/* teql is meant to be used as root qdisc */
+	return NULL;
+}
+
+static void
+teql_reset(struct Qdisc *sch)
+{
+	struct teql_sched_data *dat = qdisc_priv(sch);
+
+	skb_queue_purge(&dat->q);
+}
+
+static void
+teql_destroy(struct Qdisc *sch)
+{
+	struct Qdisc *q, *prev;
+	struct teql_sched_data *dat = qdisc_priv(sch);
+	struct teql_master *master = dat->m;
+
+	if (!master)
+		return;
+
+	prev = master->slaves;
+	if (prev) {
+		do {
+			q = NEXT_SLAVE(prev);
+			if (q == sch) {
+				NEXT_SLAVE(prev) = NEXT_SLAVE(q);
+				if (q == master->slaves) {
+					master->slaves = NEXT_SLAVE(q);
+					if (q == master->slaves) {
+						struct netdev_queue *txq;
+						spinlock_t *root_lock;
+
+						txq = netdev_get_tx_queue(master->dev, 0);
+						master->slaves = NULL;
+
+						root_lock = qdisc_root_sleeping_lock(rtnl_dereference(txq->qdisc));
+						spin_lock_bh(root_lock);
+						qdisc_reset(rtnl_dereference(txq->qdisc));
+						spin_unlock_bh(root_lock);
+					}
+				}
+				skb_queue_purge(&dat->q);
+				break;
+			}
+
+		} while ((prev = q) != master->slaves);
+	}
+}
+
+static int teql_qdisc_init(struct Qdisc *sch, struct nlattr *opt,
+			   struct netlink_ext_ack *extack)
+{
+	struct net_device *dev = qdisc_dev(sch);
+	struct teql_master *m = (struct teql_master *)sch->ops;
+	struct teql_sched_data *q = qdisc_priv(sch);
+
+	if (dev->hard_header_len > m->dev->hard_header_len)
+		return -EINVAL;
+
+	if (m->dev == dev)
+		return -ELOOP;
+
+	q->m = m;
+
+	skb_queue_head_init(&q->q);
+
+	if (m->slaves) {
+		if (m->dev->flags & IFF_UP) {
+			if ((m->dev->flags & IFF_POINTOPOINT &&
+			     !(dev->flags & IFF_POINTOPOINT)) ||
+			    (m->dev->flags & IFF_BROADCAST &&
+			     !(dev->flags & IFF_BROADCAST)) ||
+			    (m->dev->flags & IFF_MULTICAST &&
+			     !(dev->flags & IFF_MULTICAST)) ||
+			    dev->mtu < m->dev->mtu)
+				return -EINVAL;
+		} else {
+			if (!(dev->flags&IFF_POINTOPOINT))
+				m->dev->flags &= ~IFF_POINTOPOINT;
+			if (!(dev->flags&IFF_BROADCAST))
+				m->dev->flags &= ~IFF_BROADCAST;
+			if (!(dev->flags&IFF_MULTICAST))
+				m->dev->flags &= ~IFF_MULTICAST;
+			if (dev->mtu < m->dev->mtu)
+				m->dev->mtu = dev->mtu;
+		}
+		q->next = NEXT_SLAVE(m->slaves);
+		NEXT_SLAVE(m->slaves) = sch;
+	} else {
+		q->next = sch;
+		m->slaves = sch;
+		m->dev->mtu = dev->mtu;
+		m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK);
+	}
+	return 0;
+}
+
+
+static int
+__teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res,
+	       struct net_device *dev, struct netdev_queue *txq,
+	       struct dst_entry *dst)
+{
+	struct neighbour *n;
+	int err = 0;
+
+	n = dst_neigh_lookup_skb(dst, skb);
+	if (!n)
+		return -ENOENT;
+
+	if (dst->dev != dev) {
+		struct neighbour *mn;
+
+		mn = __neigh_lookup_errno(n->tbl, n->primary_key, dev);
+		neigh_release(n);
+		if (IS_ERR(mn))
+			return PTR_ERR(mn);
+		n = mn;
+	}
+
+	if (neigh_event_send(n, skb_res) == 0) {
+		int err;
+		char haddr[MAX_ADDR_LEN];
+
+		neigh_ha_snapshot(haddr, n, dev);
+		err = dev_hard_header(skb, dev, ntohs(skb_protocol(skb, false)),
+				      haddr, NULL, skb->len);
+
+		if (err < 0)
+			err = -EINVAL;
+	} else {
+		err = (skb_res == NULL) ? -EAGAIN : 1;
+	}
+	neigh_release(n);
+	return err;
+}
+
+static inline int teql_resolve(struct sk_buff *skb,
+			       struct sk_buff *skb_res,
+			       struct net_device *dev,
+			       struct netdev_queue *txq)
+{
+	struct dst_entry *dst = skb_dst(skb);
+	int res;
+
+	if (rcu_access_pointer(txq->qdisc) == &noop_qdisc)
+		return -ENODEV;
+
+	if (!dev->header_ops || !dst)
+		return 0;
+
+	rcu_read_lock();
+	res = __teql_resolve(skb, skb_res, dev, txq, dst);
+	rcu_read_unlock();
+
+	return res;
+}
+
+static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct teql_master *master = netdev_priv(dev);
+	struct Qdisc *start, *q;
+	int busy;
+	int nores;
+	int subq = skb_get_queue_mapping(skb);
+	struct sk_buff *skb_res = NULL;
+
+	start = master->slaves;
+
+restart:
+	nores = 0;
+	busy = 0;
+
+	q = start;
+	if (!q)
+		goto drop;
+
+	do {
+		struct net_device *slave = qdisc_dev(q);
+		struct netdev_queue *slave_txq = netdev_get_tx_queue(slave, 0);
+
+		if (rcu_access_pointer(slave_txq->qdisc_sleeping) != q)
+			continue;
+		if (netif_xmit_stopped(netdev_get_tx_queue(slave, subq)) ||
+		    !netif_running(slave)) {
+			busy = 1;
+			continue;
+		}
+
+		switch (teql_resolve(skb, skb_res, slave, slave_txq)) {
+		case 0:
+			if (__netif_tx_trylock(slave_txq)) {
+				unsigned int length = qdisc_pkt_len(skb);
+
+				if (!netif_xmit_frozen_or_stopped(slave_txq) &&
+				    netdev_start_xmit(skb, slave, slave_txq, false) ==
+				    NETDEV_TX_OK) {
+					__netif_tx_unlock(slave_txq);
+					master->slaves = NEXT_SLAVE(q);
+					netif_wake_queue(dev);
+					master->tx_packets++;
+					master->tx_bytes += length;
+					return NETDEV_TX_OK;
+				}
+				__netif_tx_unlock(slave_txq);
+			}
+			if (netif_xmit_stopped(netdev_get_tx_queue(dev, 0)))
+				busy = 1;
+			break;
+		case 1:
+			master->slaves = NEXT_SLAVE(q);
+			return NETDEV_TX_OK;
+		default:
+			nores = 1;
+			break;
+		}
+		__skb_pull(skb, skb_network_offset(skb));
+	} while ((q = NEXT_SLAVE(q)) != start);
+
+	if (nores && skb_res == NULL) {
+		skb_res = skb;
+		goto restart;
+	}
+
+	if (busy) {
+		netif_stop_queue(dev);
+		return NETDEV_TX_BUSY;
+	}
+	master->tx_errors++;
+
+drop:
+	master->tx_dropped++;
+	dev_kfree_skb(skb);
+	return NETDEV_TX_OK;
+}
+
+static int teql_master_open(struct net_device *dev)
+{
+	struct Qdisc *q;
+	struct teql_master *m = netdev_priv(dev);
+	int mtu = 0xFFFE;
+	unsigned int flags = IFF_NOARP | IFF_MULTICAST;
+
+	if (m->slaves == NULL)
+		return -EUNATCH;
+
+	flags = FMASK;
+
+	q = m->slaves;
+	do {
+		struct net_device *slave = qdisc_dev(q);
+
+		if (slave == NULL)
+			return -EUNATCH;
+
+		if (slave->mtu < mtu)
+			mtu = slave->mtu;
+		if (slave->hard_header_len > LL_MAX_HEADER)
+			return -EINVAL;
+
+		/* If all the slaves are BROADCAST, master is BROADCAST
+		   If all the slaves are PtP, master is PtP
+		   Otherwise, master is NBMA.
+		 */
+		if (!(slave->flags&IFF_POINTOPOINT))
+			flags &= ~IFF_POINTOPOINT;
+		if (!(slave->flags&IFF_BROADCAST))
+			flags &= ~IFF_BROADCAST;
+		if (!(slave->flags&IFF_MULTICAST))
+			flags &= ~IFF_MULTICAST;
+	} while ((q = NEXT_SLAVE(q)) != m->slaves);
+
+	m->dev->mtu = mtu;
+	m->dev->flags = (m->dev->flags&~FMASK) | flags;
+	netif_start_queue(m->dev);
+	return 0;
+}
+
+static int teql_master_close(struct net_device *dev)
+{
+	netif_stop_queue(dev);
+	return 0;
+}
+
+static void teql_master_stats64(struct net_device *dev,
+				struct rtnl_link_stats64 *stats)
+{
+	struct teql_master *m = netdev_priv(dev);
+
+	stats->tx_packets	= m->tx_packets;
+	stats->tx_bytes		= m->tx_bytes;
+	stats->tx_errors	= m->tx_errors;
+	stats->tx_dropped	= m->tx_dropped;
+}
+
+static int teql_master_mtu(struct net_device *dev, int new_mtu)
+{
+	struct teql_master *m = netdev_priv(dev);
+	struct Qdisc *q;
+
+	q = m->slaves;
+	if (q) {
+		do {
+			if (new_mtu > qdisc_dev(q)->mtu)
+				return -EINVAL;
+		} while ((q = NEXT_SLAVE(q)) != m->slaves);
+	}
+
+	dev->mtu = new_mtu;
+	return 0;
+}
+
+static const struct net_device_ops teql_netdev_ops = {
+	.ndo_open	= teql_master_open,
+	.ndo_stop	= teql_master_close,
+	.ndo_start_xmit	= teql_master_xmit,
+	.ndo_get_stats64 = teql_master_stats64,
+	.ndo_change_mtu	= teql_master_mtu,
+};
+
+static __init void teql_master_setup(struct net_device *dev)
+{
+	struct teql_master *master = netdev_priv(dev);
+	struct Qdisc_ops *ops = &master->qops;
+
+	master->dev	= dev;
+	ops->priv_size  = sizeof(struct teql_sched_data);
+
+	ops->enqueue	=	teql_enqueue;
+	ops->dequeue	=	teql_dequeue;
+	ops->peek	=	teql_peek;
+	ops->init	=	teql_qdisc_init;
+	ops->reset	=	teql_reset;
+	ops->destroy	=	teql_destroy;
+	ops->owner	=	THIS_MODULE;
+
+	dev->netdev_ops =       &teql_netdev_ops;
+	dev->type		= ARPHRD_VOID;
+	dev->mtu		= 1500;
+	dev->min_mtu		= 68;
+	dev->max_mtu		= 65535;
+	dev->tx_queue_len	= 100;
+	dev->flags		= IFF_NOARP;
+	dev->hard_header_len	= LL_MAX_HEADER;
+	netif_keep_dst(dev);
+}
+
+static LIST_HEAD(master_dev_list);
+static int max_equalizers = 1;
+module_param(max_equalizers, int, 0);
+MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers");
+
+static int __init teql_init(void)
+{
+	int i;
+	int err = -ENODEV;
+
+	for (i = 0; i < max_equalizers; i++) {
+		struct net_device *dev;
+		struct teql_master *master;
+
+		dev = alloc_netdev(sizeof(struct teql_master), "teql%d",
+				   NET_NAME_UNKNOWN, teql_master_setup);
+		if (!dev) {
+			err = -ENOMEM;
+			break;
+		}
+
+		if ((err = register_netdev(dev))) {
+			free_netdev(dev);
+			break;
+		}
+
+		master = netdev_priv(dev);
+
+		strscpy(master->qops.id, dev->name, IFNAMSIZ);
+		err = register_qdisc(&master->qops);
+
+		if (err) {
+			unregister_netdev(dev);
+			free_netdev(dev);
+			break;
+		}
+
+		list_add_tail(&master->master_list, &master_dev_list);
+	}
+	return i ? 0 : err;
+}
+
+static void __exit teql_exit(void)
+{
+	struct teql_master *master, *nxt;
+
+	list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) {
+
+		list_del(&master->master_list);
+
+		unregister_qdisc(&master->qops);
+		unregister_netdev(master->dev);
+		free_netdev(master->dev);
+	}
+}
+
+module_init(teql_init);
+module_exit(teql_exit);
+
+MODULE_LICENSE("GPL");