Root/drivers/net/ifb.c

1/* drivers/net/ifb.c:
2
3    The purpose of this driver is to provide a device that allows
4    for sharing of resources:
5
6    1) qdiscs/policies that are per device as opposed to system wide.
7    ifb allows for a device which can be redirected to thus providing
8    an impression of sharing.
9
10    2) Allows for queueing incoming traffic for shaping instead of
11    dropping.
12
13    The original concept is based on what is known as the IMQ
14    driver initially written by Martin Devera, later rewritten
15    by Patrick McHardy and then maintained by Andre Correa.
16
17    You need the tc action mirror or redirect to feed this device
18           packets.
19
20    This program is free software; you can redistribute it and/or
21    modify it under the terms of the GNU General Public License
22    as published by the Free Software Foundation; either version
23    2 of the License, or (at your option) any later version.
24
25      Authors: Jamal Hadi Salim (2005)
26
27*/
28
29
30#include <linux/module.h>
31#include <linux/kernel.h>
32#include <linux/netdevice.h>
33#include <linux/etherdevice.h>
34#include <linux/init.h>
35#include <linux/moduleparam.h>
36#include <net/pkt_sched.h>
37#include <net/net_namespace.h>
38
39#define TX_TIMEOUT (2*HZ)
40
41#define TX_Q_LIMIT 32
42struct ifb_private {
43    struct tasklet_struct ifb_tasklet;
44    int tasklet_pending;
45    /* mostly debug stats leave in for now */
46    unsigned long st_task_enter; /* tasklet entered */
47    unsigned long st_txq_refl_try; /* transmit queue refill attempt */
48    unsigned long st_rxq_enter; /* receive queue entered */
49    unsigned long st_rx2tx_tran; /* receive to trasmit transfers */
50    unsigned long st_rxq_notenter; /*receiveQ not entered, resched */
51    unsigned long st_rx_frm_egr; /* received from egress path */
52    unsigned long st_rx_frm_ing; /* received from ingress path */
53    unsigned long st_rxq_check;
54    unsigned long st_rxq_rsch;
55    struct sk_buff_head rq;
56    struct sk_buff_head tq;
57};
58
59static int numifbs = 2;
60
61static void ri_tasklet(unsigned long dev);
62static int ifb_xmit(struct sk_buff *skb, struct net_device *dev);
63static int ifb_open(struct net_device *dev);
64static int ifb_close(struct net_device *dev);
65
66static void ri_tasklet(unsigned long dev)
67{
68
69    struct net_device *_dev = (struct net_device *)dev;
70    struct ifb_private *dp = netdev_priv(_dev);
71    struct net_device_stats *stats = &_dev->stats;
72    struct netdev_queue *txq;
73    struct sk_buff *skb;
74
75    txq = netdev_get_tx_queue(_dev, 0);
76    dp->st_task_enter++;
77    if ((skb = skb_peek(&dp->tq)) == NULL) {
78        dp->st_txq_refl_try++;
79        if (__netif_tx_trylock(txq)) {
80            dp->st_rxq_enter++;
81            while ((skb = skb_dequeue(&dp->rq)) != NULL) {
82                skb_queue_tail(&dp->tq, skb);
83                dp->st_rx2tx_tran++;
84            }
85            __netif_tx_unlock(txq);
86        } else {
87            /* reschedule */
88            dp->st_rxq_notenter++;
89            goto resched;
90        }
91    }
92
93    while ((skb = skb_dequeue(&dp->tq)) != NULL) {
94        u32 from = G_TC_FROM(skb->tc_verd);
95
96        skb->tc_verd = 0;
97        skb->tc_verd = SET_TC_NCLS(skb->tc_verd);
98        stats->tx_packets++;
99        stats->tx_bytes +=skb->len;
100
101        skb->dev = __dev_get_by_index(&init_net, skb->iif);
102        if (!skb->dev) {
103            dev_kfree_skb(skb);
104            stats->tx_dropped++;
105            break;
106        }
107        skb->iif = _dev->ifindex;
108
109        if (from & AT_EGRESS) {
110            dp->st_rx_frm_egr++;
111            dev_queue_xmit(skb);
112        } else if (from & AT_INGRESS) {
113            dp->st_rx_frm_ing++;
114            skb_pull(skb, skb->dev->hard_header_len);
115            netif_rx(skb);
116        } else
117            BUG();
118    }
119
120    if (__netif_tx_trylock(txq)) {
121        dp->st_rxq_check++;
122        if ((skb = skb_peek(&dp->rq)) == NULL) {
123            dp->tasklet_pending = 0;
124            if (netif_queue_stopped(_dev))
125                netif_wake_queue(_dev);
126        } else {
127            dp->st_rxq_rsch++;
128            __netif_tx_unlock(txq);
129            goto resched;
130        }
131        __netif_tx_unlock(txq);
132    } else {
133resched:
134        dp->tasklet_pending = 1;
135        tasklet_schedule(&dp->ifb_tasklet);
136    }
137
138}
139
140static const struct net_device_ops ifb_netdev_ops = {
141    .ndo_open = ifb_open,
142    .ndo_stop = ifb_close,
143    .ndo_start_xmit = ifb_xmit,
144    .ndo_validate_addr = eth_validate_addr,
145};
146
147static void ifb_setup(struct net_device *dev)
148{
149    /* Initialize the device structure. */
150    dev->destructor = free_netdev;
151    dev->netdev_ops = &ifb_netdev_ops;
152
153    /* Fill in device structure with ethernet-generic values. */
154    ether_setup(dev);
155    dev->tx_queue_len = TX_Q_LIMIT;
156
157    dev->flags |= IFF_NOARP;
158    dev->flags &= ~IFF_MULTICAST;
159    dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
160    random_ether_addr(dev->dev_addr);
161}
162
163static int ifb_xmit(struct sk_buff *skb, struct net_device *dev)
164{
165    struct ifb_private *dp = netdev_priv(dev);
166    struct net_device_stats *stats = &dev->stats;
167    int ret = 0;
168    u32 from = G_TC_FROM(skb->tc_verd);
169
170    stats->rx_packets++;
171    stats->rx_bytes+=skb->len;
172
173    if (!(from & (AT_INGRESS|AT_EGRESS)) || !skb->iif) {
174        dev_kfree_skb(skb);
175        stats->rx_dropped++;
176        return ret;
177    }
178
179    if (skb_queue_len(&dp->rq) >= dev->tx_queue_len) {
180        netif_stop_queue(dev);
181    }
182
183    dev->trans_start = jiffies;
184    skb_queue_tail(&dp->rq, skb);
185    if (!dp->tasklet_pending) {
186        dp->tasklet_pending = 1;
187        tasklet_schedule(&dp->ifb_tasklet);
188    }
189
190    return ret;
191}
192
193static int ifb_close(struct net_device *dev)
194{
195    struct ifb_private *dp = netdev_priv(dev);
196
197    tasklet_kill(&dp->ifb_tasklet);
198    netif_stop_queue(dev);
199    skb_queue_purge(&dp->rq);
200    skb_queue_purge(&dp->tq);
201    return 0;
202}
203
204static int ifb_open(struct net_device *dev)
205{
206    struct ifb_private *dp = netdev_priv(dev);
207
208    tasklet_init(&dp->ifb_tasklet, ri_tasklet, (unsigned long)dev);
209    skb_queue_head_init(&dp->rq);
210    skb_queue_head_init(&dp->tq);
211    netif_start_queue(dev);
212
213    return 0;
214}
215
216static int ifb_validate(struct nlattr *tb[], struct nlattr *data[])
217{
218    if (tb[IFLA_ADDRESS]) {
219        if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
220            return -EINVAL;
221        if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
222            return -EADDRNOTAVAIL;
223    }
224    return 0;
225}
226
227static struct rtnl_link_ops ifb_link_ops __read_mostly = {
228    .kind = "ifb",
229    .priv_size = sizeof(struct ifb_private),
230    .setup = ifb_setup,
231    .validate = ifb_validate,
232};
233
234/* Number of ifb devices to be set up by this module. */
235module_param(numifbs, int, 0);
236MODULE_PARM_DESC(numifbs, "Number of ifb devices");
237
238static int __init ifb_init_one(int index)
239{
240    struct net_device *dev_ifb;
241    int err;
242
243    dev_ifb = alloc_netdev(sizeof(struct ifb_private),
244                 "ifb%d", ifb_setup);
245
246    if (!dev_ifb)
247        return -ENOMEM;
248
249    err = dev_alloc_name(dev_ifb, dev_ifb->name);
250    if (err < 0)
251        goto err;
252
253    dev_ifb->rtnl_link_ops = &ifb_link_ops;
254    err = register_netdevice(dev_ifb);
255    if (err < 0)
256        goto err;
257
258    return 0;
259
260err:
261    free_netdev(dev_ifb);
262    return err;
263}
264
265static int __init ifb_init_module(void)
266{
267    int i, err;
268
269    rtnl_lock();
270    err = __rtnl_link_register(&ifb_link_ops);
271
272    for (i = 0; i < numifbs && !err; i++)
273        err = ifb_init_one(i);
274    if (err)
275        __rtnl_link_unregister(&ifb_link_ops);
276    rtnl_unlock();
277
278    return err;
279}
280
281static void __exit ifb_cleanup_module(void)
282{
283    rtnl_link_unregister(&ifb_link_ops);
284}
285
286module_init(ifb_init_module);
287module_exit(ifb_cleanup_module);
288MODULE_LICENSE("GPL");
289MODULE_AUTHOR("Jamal Hadi Salim");
290MODULE_ALIAS_RTNL_LINK("ifb");
291

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