net/phonet/pep-gprs.c

   1 /*
   2  * File: pep-gprs.c
   3  *
   4  * GPRS over Phonet pipe end point socket
   5  *
   6  * Copyright (C) 2008 Nokia Corporation.
   7  *
   8  * Author: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * version 2 as published by the Free Software Foundation.
  13  *
  14  * This program is distributed in the hope that it will be useful, but
  15  * WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  22  * 02110-1301 USA
  23  */
  24
  25 #include <linux/kernel.h>
  26 #include <linux/netdevice.h>
  27 #include <linux/if_ether.h>
  28 #include <linux/if_arp.h>
  29 #include <net/sock.h>
  30
  31 #include <linux/if_phonet.h>
  32 #include <net/tcp_states.h>
  33 #include <net/phonet/gprs.h>
  34
  35 #define GPRS_DEFAULT_MTU 1400
  36
  37 struct gprs_dev {
  38         struct sock             *sk;
  39         void                    (*old_state_change)(struct sock *);
  40         void                    (*old_data_ready)(struct sock *, int);
  41         void                    (*old_write_space)(struct sock *);
  42
  43         struct net_device       *net;
  44
  45         struct sk_buff_head     tx_queue;
  46         struct work_struct      tx_work;
  47         spinlock_t              tx_lock;
  48         unsigned                tx_max;
  49 };
  50
  51 static __be16 gprs_type_trans(struct sk_buff *skb)
  52 {
  53         const u8 *pvfc;
  54         u8 buf;
  55
  56         pvfc = skb_header_pointer(skb, 0, 1, &buf);
  57         if (!pvfc)
  58                 return htons(0);
  59         /* Look at IP version field */
  60         switch (*pvfc >> 4) {
  61         case 4:
  62                 return htons(ETH_P_IP);
  63         case 6:
  64                 return htons(ETH_P_IPV6);
  65         }
  66         return htons(0);
  67 }
  68
  69 /*
  70  * Socket callbacks
  71  */
  72
  73 static void gprs_state_change(struct sock *sk)
  74 {
  75         struct gprs_dev *dev = sk->sk_user_data;
  76
  77         if (sk->sk_state == TCP_CLOSE_WAIT) {
  78                 netif_stop_queue(dev->net);
  79                 netif_carrier_off(dev->net);
  80         }
  81 }
  82
  83 static int gprs_recv(struct gprs_dev *dev, struct sk_buff *skb)
  84 {
  85         struct net_device *net = dev->net;
  86         int err = 0;
  87         __be16 protocol = gprs_type_trans(skb);
  88
  89         if (!protocol) {
  90                 err = -EINVAL;
  91                 goto drop;
  92         }
  93
  94         if (likely(skb_headroom(skb) & 3)) {
  95                 struct sk_buff *rskb, *fs;
  96                 int flen = 0;
  97
  98                 /* Phonet Pipe data header is misaligned (3 bytes),
  99                  * so wrap the IP packet as a single fragment of an head-less
 100                  * socket buffer. The network stack will pull what it needs,
 101                  * but at least, the whole IP payload is not memcpy'd. */
 102                 rskb = netdev_alloc_skb(net, 0);
 103                 if (!rskb) {
 104                         err = -ENOBUFS;
 105                         goto drop;
 106                 }
 107                 skb_shinfo(rskb)->frag_list = skb;
 108                 rskb->len += skb->len;
 109                 rskb->data_len += rskb->len;
 110                 rskb->truesize += rskb->len;
 111
 112                 /* Avoid nested fragments */
 113                 for (fs = skb_shinfo(skb)->frag_list; fs; fs = fs->next)
 114                         flen += fs->len;
 115                 skb->next = skb_shinfo(skb)->frag_list;
 116                 skb_shinfo(skb)->frag_list = NULL;
 117                 skb->len -= flen;
 118                 skb->data_len -= flen;
 119                 skb->truesize -= flen;
 120
 121                 skb = rskb;
 122         }
 123
 124         skb->protocol = protocol;
 125         skb_reset_mac_header(skb);
 126         skb->dev = net;
 127
 128         if (likely(net->flags & IFF_UP)) {
 129                 net->stats.rx_packets++;
 130                 net->stats.rx_bytes += skb->len;
 131                 netif_rx(skb);
 132                 skb = NULL;
 133         } else
 134                 err = -ENODEV;
 135
 136 drop:
 137         if (skb) {
 138                 dev_kfree_skb(skb);
 139                 net->stats.rx_dropped++;
 140         }
 141         return err;
 142 }
 143
 144 static void gprs_data_ready(struct sock *sk, int len)
 145 {
 146         struct gprs_dev *dev = sk->sk_user_data;
 147         struct sk_buff *skb;
 148
 149         while ((skb = pep_read(sk)) != NULL) {
 150                 skb_orphan(skb);
 151                 gprs_recv(dev, skb);
 152         }
 153 }
 154
 155 static void gprs_write_space(struct sock *sk)
 156 {
 157         struct gprs_dev *dev = sk->sk_user_data;
 158         unsigned credits = pep_writeable(sk);
 159
 160         spin_lock_bh(&dev->tx_lock);
 161         dev->tx_max = credits;
 162         if (credits > skb_queue_len(&dev->tx_queue))
 163                 netif_wake_queue(dev->net);
 164         spin_unlock_bh(&dev->tx_lock);
 165 }
 166
 167 /*
 168  * Network device callbacks
 169  */
 170
 171 static int gprs_xmit(struct sk_buff *skb, struct net_device *net)
 172 {
 173         struct gprs_dev *dev = netdev_priv(net);
 174
 175         switch (skb->protocol) {
 176         case  htons(ETH_P_IP):
 177         case  htons(ETH_P_IPV6):
 178                 break;
 179         default:
 180                 dev_kfree_skb(skb);
 181                 return 0;
 182         }
 183
 184         spin_lock(&dev->tx_lock);
 185         if (likely(skb_queue_len(&dev->tx_queue) < dev->tx_max)) {
 186                 skb_queue_tail(&dev->tx_queue, skb);
 187                 skb = NULL;
 188         }
 189         if (skb_queue_len(&dev->tx_queue) >= dev->tx_max)
 190                 netif_stop_queue(net);
 191         spin_unlock(&dev->tx_lock);
 192
 193         schedule_work(&dev->tx_work);
 194         if (unlikely(skb))
 195                 dev_kfree_skb(skb);
 196         return 0;
 197 }
 198
 199 static void gprs_tx(struct work_struct *work)
 200 {
 201         struct gprs_dev *dev = container_of(work, struct gprs_dev, tx_work);
 202         struct net_device *net = dev->net;
 203         struct sock *sk = dev->sk;
 204         struct sk_buff *skb;
 205
 206         while ((skb = skb_dequeue(&dev->tx_queue)) != NULL) {
 207                 int err;
 208
 209                 net->stats.tx_bytes += skb->len;
 210                 net->stats.tx_packets++;
 211
 212                 skb_orphan(skb);
 213                 skb_set_owner_w(skb, sk);
 214
 215                 lock_sock(sk);
 216                 err = pep_write(sk, skb);
 217                 if (err) {
 218                         LIMIT_NETDEBUG(KERN_WARNING"%s: TX error (%d)\n",
 219                                         net->name, err);
 220                         net->stats.tx_aborted_errors++;
 221                         net->stats.tx_errors++;
 222                 }
 223                 release_sock(sk);
 224         }
 225
 226         lock_sock(sk);
 227         gprs_write_space(sk);
 228         release_sock(sk);
 229 }
 230
 231 static int gprs_set_mtu(struct net_device *net, int new_mtu)
 232 {
 233         if ((new_mtu < 576) || (new_mtu > (PHONET_MAX_MTU - 11)))
 234                 return -EINVAL;
 235
 236         net->mtu = new_mtu;
 237         return 0;
 238 }
 239
 240 static void gprs_setup(struct net_device *net)
 241 {
 242         net->features           = NETIF_F_FRAGLIST;
 243         net->type               = ARPHRD_NONE;
 244         net->flags              = IFF_POINTOPOINT | IFF_NOARP;
 245         net->mtu                = GPRS_DEFAULT_MTU;
 246         net->hard_header_len    = 0;
 247         net->addr_len           = 0;
 248         net->tx_queue_len       = 10;
 249
 250         net->destructor         = free_netdev;
 251         net->hard_start_xmit    = gprs_xmit; /* mandatory */
 252         net->change_mtu         = gprs_set_mtu;
 253 }
 254
 255 /*
 256  * External interface
 257  */
 258
 259 /*
 260  * Attach a GPRS interface to a datagram socket.
 261  * Returns the interface index on success, negative error code on error.
 262  */
 263 int gprs_attach(struct sock *sk)
 264 {
 265         static const char ifname[] = "gprs%d";
 266         struct gprs_dev *dev;
 267         struct net_device *net;
 268         int err;
 269
 270         if (unlikely(sk->sk_type == SOCK_STREAM))
 271                 return -EINVAL; /* need packet boundaries */
 272
 273         /* Create net device */
 274         net = alloc_netdev(sizeof(*dev), ifname, gprs_setup);
 275         if (!net)
 276                 return -ENOMEM;
 277         dev = netdev_priv(net);
 278         dev->net = net;
 279         dev->tx_max = 0;
 280         spin_lock_init(&dev->tx_lock);
 281         skb_queue_head_init(&dev->tx_queue);
 282         INIT_WORK(&dev->tx_work, gprs_tx);
 283
 284         netif_stop_queue(net);
 285         err = register_netdev(net);
 286         if (err) {
 287                 free_netdev(net);
 288                 return err;
 289         }
 290
 291         lock_sock(sk);
 292         if (unlikely(sk->sk_user_data)) {
 293                 err = -EBUSY;
 294                 goto out_rel;
 295         }
 296         if (unlikely((1 << sk->sk_state & (TCPF_CLOSE|TCPF_LISTEN)) ||
 297                         sock_flag(sk, SOCK_DEAD))) {
 298                 err = -EINVAL;
 299                 goto out_rel;
 300         }
 301         sk->sk_user_data        = dev;
 302         dev->old_state_change   = sk->sk_state_change;
 303         dev->old_data_ready     = sk->sk_data_ready;
 304         dev->old_write_space    = sk->sk_write_space;
 305         sk->sk_state_change     = gprs_state_change;
 306         sk->sk_data_ready       = gprs_data_ready;
 307         sk->sk_write_space      = gprs_write_space;
 308         release_sock(sk);
 309
 310         sock_hold(sk);
 311         dev->sk = sk;
 312
 313         printk(KERN_DEBUG"%s: attached\n", net->name);
 314         gprs_write_space(sk); /* kick off TX */
 315         return net->ifindex;
 316
 317 out_rel:
 318         release_sock(sk);
 319         unregister_netdev(net);
 320         return err;
 321 }
 322
 323 void gprs_detach(struct sock *sk)
 324 {
 325         struct gprs_dev *dev = sk->sk_user_data;
 326         struct net_device *net = dev->net;
 327
 328         lock_sock(sk);
 329         sk->sk_user_data        = NULL;
 330         sk->sk_state_change     = dev->old_state_change;
 331         sk->sk_data_ready       = dev->old_data_ready;
 332         sk->sk_write_space      = dev->old_write_space;
 333         release_sock(sk);
 334
 335         printk(KERN_DEBUG"%s: detached\n", net->name);
 336         unregister_netdev(net);
 337         flush_scheduled_work();
 338         sock_put(sk);
 339         skb_queue_purge(&dev->tx_queue);
 340 }