git.oblomov.eu Git - linux-2.6/blob - drivers/net/ppp_generic.c

   1 /*
   2  * Generic PPP layer for Linux.
   3  *
   4  * Copyright 1999-2002 Paul Mackerras.
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  *
  11  * The generic PPP layer handles the PPP network interfaces, the
  12  * /dev/ppp device, packet and VJ compression, and multilink.
  13  * It talks to PPP `channels' via the interface defined in
  14  * include/linux/ppp_channel.h.  Channels provide the basic means for
  15  * sending and receiving PPP frames on some kind of communications
  16  * channel.
  17  *
  18  * Part of the code in this driver was inspired by the old async-only
  19  * PPP driver, written by Michael Callahan and Al Longyear, and
  20  * subsequently hacked by Paul Mackerras.
  21  *
  22  * ==FILEVERSION 20041108==
  23  */
  24
  25 #include <linux/config.h>
  26 #include <linux/module.h>
  27 #include <linux/kernel.h>
  28 #include <linux/kmod.h>
  29 #include <linux/init.h>
  30 #include <linux/list.h>
  31 #include <linux/devfs_fs_kernel.h>
  32 #include <linux/netdevice.h>
  33 #include <linux/poll.h>
  34 #include <linux/ppp_defs.h>
  35 #include <linux/filter.h>
  36 #include <linux/if_ppp.h>
  37 #include <linux/ppp_channel.h>
  38 #include <linux/ppp-comp.h>
  39 #include <linux/skbuff.h>
  40 #include <linux/rtnetlink.h>
  41 #include <linux/if_arp.h>
  42 #include <linux/ip.h>
  43 #include <linux/tcp.h>
  44 #include <linux/spinlock.h>
  45 #include <linux/smp_lock.h>
  46 #include <linux/rwsem.h>
  47 #include <linux/stddef.h>
  48 #include <linux/device.h>
  49 #include <net/slhc_vj.h>
  50 #include <asm/atomic.h>
  51
  52 #define PPP_VERSION     "2.4.2"
  53
  54 /*
  55  * Network protocols we support.
  56  */
  57 #define NP_IP   0               /* Internet Protocol V4 */
  58 #define NP_IPV6 1               /* Internet Protocol V6 */
  59 #define NP_IPX  2               /* IPX protocol */
  60 #define NP_AT   3               /* Appletalk protocol */
  61 #define NP_MPLS_UC 4            /* MPLS unicast */
  62 #define NP_MPLS_MC 5            /* MPLS multicast */
  63 #define NUM_NP  6               /* Number of NPs. */
  64
  65 #define MPHDRLEN        6       /* multilink protocol header length */
  66 #define MPHDRLEN_SSN    4       /* ditto with short sequence numbers */
  67 #define MIN_FRAG_SIZE   64
  68
  69 /*
  70  * An instance of /dev/ppp can be associated with either a ppp
  71  * interface unit or a ppp channel.  In both cases, file->private_data
  72  * points to one of these.
  73  */
  74 struct ppp_file {
  75         enum {
  76                 INTERFACE=1, CHANNEL
  77         }               kind;
  78         struct sk_buff_head xq;         /* pppd transmit queue */
  79         struct sk_buff_head rq;         /* receive queue for pppd */
  80         wait_queue_head_t rwait;        /* for poll on reading /dev/ppp */
  81         atomic_t        refcnt;         /* # refs (incl /dev/ppp attached) */
  82         int             hdrlen;         /* space to leave for headers */
  83         int             index;          /* interface unit / channel number */
  84         int             dead;           /* unit/channel has been shut down */
  85 };
  86
  87 #define PF_TO_X(pf, X)          ((X *)((char *)(pf) - offsetof(X, file)))
  88
  89 #define PF_TO_PPP(pf)           PF_TO_X(pf, struct ppp)
  90 #define PF_TO_CHANNEL(pf)       PF_TO_X(pf, struct channel)
  91
  92 #define ROUNDUP(n, x)           (((n) + (x) - 1) / (x))
  93
  94 /*
  95  * Data structure describing one ppp unit.
  96  * A ppp unit corresponds to a ppp network interface device
  97  * and represents a multilink bundle.
  98  * It can have 0 or more ppp channels connected to it.
  99  */
 100 struct ppp {
 101         struct ppp_file file;           /* stuff for read/write/poll 0 */
 102         struct file     *owner;         /* file that owns this unit 48 */
 103         struct list_head channels;      /* list of attached channels 4c */
 104         int             n_channels;     /* how many channels are attached 54 */
 105         spinlock_t      rlock;          /* lock for receive side 58 */
 106         spinlock_t      wlock;          /* lock for transmit side 5c */
 107         int             mru;            /* max receive unit 60 */
 108         unsigned int    flags;          /* control bits 64 */
 109         unsigned int    xstate;         /* transmit state bits 68 */
 110         unsigned int    rstate;         /* receive state bits 6c */
 111         int             debug;          /* debug flags 70 */
 112         struct slcompress *vj;          /* state for VJ header compression */
 113         enum NPmode     npmode[NUM_NP]; /* what to do with each net proto 78 */
 114         struct sk_buff  *xmit_pending;  /* a packet ready to go out 88 */
 115         struct compressor *xcomp;       /* transmit packet compressor 8c */
 116         void            *xc_state;      /* its internal state 90 */
 117         struct compressor *rcomp;       /* receive decompressor 94 */
 118         void            *rc_state;      /* its internal state 98 */
 119         unsigned long   last_xmit;      /* jiffies when last pkt sent 9c */
 120         unsigned long   last_recv;      /* jiffies when last pkt rcvd a0 */
 121         struct net_device *dev;         /* network interface device a4 */
 122 #ifdef CONFIG_PPP_MULTILINK
 123         int             nxchan;         /* next channel to send something on */
 124         u32             nxseq;          /* next sequence number to send */
 125         int             mrru;           /* MP: max reconst. receive unit */
 126         u32             nextseq;        /* MP: seq no of next packet */
 127         u32             minseq;         /* MP: min of most recent seqnos */
 128         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
 129 #endif /* CONFIG_PPP_MULTILINK */
 130         struct net_device_stats stats;  /* statistics */
 131 #ifdef CONFIG_PPP_FILTER
 132         struct sock_filter *pass_filter;        /* filter for packets to pass */
 133         struct sock_filter *active_filter;/* filter for pkts to reset idle */
 134         unsigned pass_len, active_len;
 135 #endif /* CONFIG_PPP_FILTER */
 136 };
 137
 138 /*
 139  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
 140  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP.
 141  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
 142  * Bits in xstate: SC_COMP_RUN
 143  */
 144 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
 145                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
 146                          |SC_COMP_TCP|SC_REJ_COMP_TCP)
 147
 148 /*
 149  * Private data structure for each channel.
 150  * This includes the data structure used for multilink.
 151  */
 152 struct channel {
 153         struct ppp_file file;           /* stuff for read/write/poll */
 154         struct list_head list;          /* link in all/new_channels list */
 155         struct ppp_channel *chan;       /* public channel data structure */
 156         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
 157         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
 158         struct ppp      *ppp;           /* ppp unit we're connected to */
 159         struct list_head clist;         /* link in list of channels per unit */
 160         rwlock_t        upl;            /* protects `ppp' */
 161 #ifdef CONFIG_PPP_MULTILINK
 162         u8              avail;          /* flag used in multilink stuff */
 163         u8              had_frag;       /* >= 1 fragments have been sent */
 164         u32             lastseq;        /* MP: last sequence # received */
 165 #endif /* CONFIG_PPP_MULTILINK */
 166 };
 167
 168 /*
 169  * SMP locking issues:
 170  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
 171  * list and the ppp.n_channels field, you need to take both locks
 172  * before you modify them.
 173  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
 174  * channel.downl.
 175  */
 176
 177 /*
 178  * A cardmap represents a mapping from unsigned integers to pointers,
 179  * and provides a fast "find lowest unused number" operation.
 180  * It uses a broad (32-way) tree with a bitmap at each level.
 181  * It is designed to be space-efficient for small numbers of entries
 182  * and time-efficient for large numbers of entries.
 183  */
 184 #define CARDMAP_ORDER   5
 185 #define CARDMAP_WIDTH   (1U << CARDMAP_ORDER)
 186 #define CARDMAP_MASK    (CARDMAP_WIDTH - 1)
 187
 188 struct cardmap {
 189         int shift;
 190         unsigned long inuse;
 191         struct cardmap *parent;
 192         void *ptr[CARDMAP_WIDTH];
 193 };
 194 static void *cardmap_get(struct cardmap *map, unsigned int nr);
 195 static void cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
 196 static unsigned int cardmap_find_first_free(struct cardmap *map);
 197 static void cardmap_destroy(struct cardmap **map);
 198
 199 /*
 200  * all_ppp_sem protects the all_ppp_units mapping.
 201  * It also ensures that finding a ppp unit in the all_ppp_units map
 202  * and updating its file.refcnt field is atomic.
 203  */
 204 static DECLARE_MUTEX(all_ppp_sem);
 205 static struct cardmap *all_ppp_units;
 206 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 207
 208 /*
 209  * all_channels_lock protects all_channels and last_channel_index,
 210  * and the atomicity of find a channel and updating its file.refcnt
 211  * field.
 212  */
 213 static DEFINE_SPINLOCK(all_channels_lock);
 214 static LIST_HEAD(all_channels);
 215 static LIST_HEAD(new_channels);
 216 static int last_channel_index;
 217 static atomic_t channel_count = ATOMIC_INIT(0);
 218
 219 /* Get the PPP protocol number from a skb */
 220 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
 221
 222 /* We limit the length of ppp->file.rq to this (arbitrary) value */
 223 #define PPP_MAX_RQLEN   32
 224
 225 /*
 226  * Maximum number of multilink fragments queued up.
 227  * This has to be large enough to cope with the maximum latency of
 228  * the slowest channel relative to the others.  Strictly it should
 229  * depend on the number of channels and their characteristics.
 230  */
 231 #define PPP_MP_MAX_QLEN 128
 232
 233 /* Multilink header bits. */
 234 #define B       0x80            /* this fragment begins a packet */
 235 #define E       0x40            /* this fragment ends a packet */
 236
 237 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
 238 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
 239 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
 240
 241 /* Prototypes. */
 242 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 243                                 unsigned int cmd, unsigned long arg);
 244 static void ppp_xmit_process(struct ppp *ppp);
 245 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
 246 static void ppp_push(struct ppp *ppp);
 247 static void ppp_channel_push(struct channel *pch);
 248 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
 249                               struct channel *pch);
 250 static void ppp_receive_error(struct ppp *ppp);
 251 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
 252 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
 253                                             struct sk_buff *skb);
 254 #ifdef CONFIG_PPP_MULTILINK
 255 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
 256                                 struct channel *pch);
 257 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
 258 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
 259 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
 260 #endif /* CONFIG_PPP_MULTILINK */
 261 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
 262 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
 263 static void ppp_ccp_closed(struct ppp *ppp);
 264 static struct compressor *find_compressor(int type);
 265 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
 266 static struct ppp *ppp_create_interface(int unit, int *retp);
 267 static void init_ppp_file(struct ppp_file *pf, int kind);
 268 static void ppp_shutdown_interface(struct ppp *ppp);
 269 static void ppp_destroy_interface(struct ppp *ppp);
 270 static struct ppp *ppp_find_unit(int unit);
 271 static struct channel *ppp_find_channel(int unit);
 272 static int ppp_connect_channel(struct channel *pch, int unit);
 273 static int ppp_disconnect_channel(struct channel *pch);
 274 static void ppp_destroy_channel(struct channel *pch);
 275
 276 static struct class_simple *ppp_class;
 277
 278 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
 279 static inline int proto_to_npindex(int proto)
 280 {
 281         switch (proto) {
 282         case PPP_IP:
 283                 return NP_IP;
 284         case PPP_IPV6:
 285                 return NP_IPV6;
 286         case PPP_IPX:
 287                 return NP_IPX;
 288         case PPP_AT:
 289                 return NP_AT;
 290         case PPP_MPLS_UC:
 291                 return NP_MPLS_UC;
 292         case PPP_MPLS_MC:
 293                 return NP_MPLS_MC;
 294         }
 295         return -EINVAL;
 296 }
 297
 298 /* Translates an NP index into a PPP protocol number */
 299 static const int npindex_to_proto[NUM_NP] = {
 300         PPP_IP,
 301         PPP_IPV6,
 302         PPP_IPX,
 303         PPP_AT,
 304         PPP_MPLS_UC,
 305         PPP_MPLS_MC,
 306 };
 307
 308 /* Translates an ethertype into an NP index */
 309 static inline int ethertype_to_npindex(int ethertype)
 310 {
 311         switch (ethertype) {
 312         case ETH_P_IP:
 313                 return NP_IP;
 314         case ETH_P_IPV6:
 315                 return NP_IPV6;
 316         case ETH_P_IPX:
 317                 return NP_IPX;
 318         case ETH_P_PPPTALK:
 319         case ETH_P_ATALK:
 320                 return NP_AT;
 321         case ETH_P_MPLS_UC:
 322                 return NP_MPLS_UC;
 323         case ETH_P_MPLS_MC:
 324                 return NP_MPLS_MC;
 325         }
 326         return -1;
 327 }
 328
 329 /* Translates an NP index into an ethertype */
 330 static const int npindex_to_ethertype[NUM_NP] = {
 331         ETH_P_IP,
 332         ETH_P_IPV6,
 333         ETH_P_IPX,
 334         ETH_P_PPPTALK,
 335         ETH_P_MPLS_UC,
 336         ETH_P_MPLS_MC,
 337 };
 338
 339 /*
 340  * Locking shorthand.
 341  */
 342 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
 343 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
 344 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
 345 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
 346 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
 347                                      ppp_recv_lock(ppp); } while (0)
 348 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
 349                                      ppp_xmit_unlock(ppp); } while (0)
 350
 351 /*
 352  * /dev/ppp device routines.
 353  * The /dev/ppp device is used by pppd to control the ppp unit.
 354  * It supports the read, write, ioctl and poll functions.
 355  * Open instances of /dev/ppp can be in one of three states:
 356  * unattached, attached to a ppp unit, or attached to a ppp channel.
 357  */
 358 static int ppp_open(struct inode *inode, struct file *file)
 359 {
 360         /*
 361          * This could (should?) be enforced by the permissions on /dev/ppp.
 362          */
 363         if (!capable(CAP_NET_ADMIN))
 364                 return -EPERM;
 365         return 0;
 366 }
 367
 368 static int ppp_release(struct inode *inode, struct file *file)
 369 {
 370         struct ppp_file *pf = file->private_data;
 371         struct ppp *ppp;
 372
 373         if (pf != 0) {
 374                 file->private_data = NULL;
 375                 if (pf->kind == INTERFACE) {
 376                         ppp = PF_TO_PPP(pf);
 377                         if (file == ppp->owner)
 378                                 ppp_shutdown_interface(ppp);
 379                 }
 380                 if (atomic_dec_and_test(&pf->refcnt)) {
 381                         switch (pf->kind) {
 382                         case INTERFACE:
 383                                 ppp_destroy_interface(PF_TO_PPP(pf));
 384                                 break;
 385                         case CHANNEL:
 386                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
 387                                 break;
 388                         }
 389                 }
 390         }
 391         return 0;
 392 }
 393
 394 static ssize_t ppp_read(struct file *file, char __user *buf,
 395                         size_t count, loff_t *ppos)
 396 {
 397         struct ppp_file *pf = file->private_data;
 398         DECLARE_WAITQUEUE(wait, current);
 399         ssize_t ret;
 400         struct sk_buff *skb = NULL;
 401
 402         ret = count;
 403
 404         if (pf == 0)
 405                 return -ENXIO;
 406         add_wait_queue(&pf->rwait, &wait);
 407         for (;;) {
 408                 set_current_state(TASK_INTERRUPTIBLE);
 409                 skb = skb_dequeue(&pf->rq);
 410                 if (skb)
 411                         break;
 412                 ret = 0;
 413                 if (pf->dead)
 414                         break;
 415                 if (pf->kind == INTERFACE) {
 416                         /*
 417                          * Return 0 (EOF) on an interface that has no
 418                          * channels connected, unless it is looping
 419                          * network traffic (demand mode).
 420                          */
 421                         struct ppp *ppp = PF_TO_PPP(pf);
 422                         if (ppp->n_channels == 0
 423                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 424                                 break;
 425                 }
 426                 ret = -EAGAIN;
 427                 if (file->f_flags & O_NONBLOCK)
 428                         break;
 429                 ret = -ERESTARTSYS;
 430                 if (signal_pending(current))
 431                         break;
 432                 schedule();
 433         }
 434         set_current_state(TASK_RUNNING);
 435         remove_wait_queue(&pf->rwait, &wait);
 436
 437         if (skb == 0)
 438                 goto out;
 439
 440         ret = -EOVERFLOW;
 441         if (skb->len > count)
 442                 goto outf;
 443         ret = -EFAULT;
 444         if (copy_to_user(buf, skb->data, skb->len))
 445                 goto outf;
 446         ret = skb->len;
 447
 448  outf:
 449         kfree_skb(skb);
 450  out:
 451         return ret;
 452 }
 453
 454 static ssize_t ppp_write(struct file *file, const char __user *buf,
 455                          size_t count, loff_t *ppos)
 456 {
 457         struct ppp_file *pf = file->private_data;
 458         struct sk_buff *skb;
 459         ssize_t ret;
 460
 461         if (pf == 0)
 462                 return -ENXIO;
 463         ret = -ENOMEM;
 464         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
 465         if (skb == 0)
 466                 goto out;
 467         skb_reserve(skb, pf->hdrlen);
 468         ret = -EFAULT;
 469         if (copy_from_user(skb_put(skb, count), buf, count)) {
 470                 kfree_skb(skb);
 471                 goto out;
 472         }
 473
 474         skb_queue_tail(&pf->xq, skb);
 475
 476         switch (pf->kind) {
 477         case INTERFACE:
 478                 ppp_xmit_process(PF_TO_PPP(pf));
 479                 break;
 480         case CHANNEL:
 481                 ppp_channel_push(PF_TO_CHANNEL(pf));
 482                 break;
 483         }
 484
 485         ret = count;
 486
 487  out:
 488         return ret;
 489 }
 490
 491 /* No kernel lock - fine */
 492 static unsigned int ppp_poll(struct file *file, poll_table *wait)
 493 {
 494         struct ppp_file *pf = file->private_data;
 495         unsigned int mask;
 496
 497         if (pf == 0)
 498                 return 0;
 499         poll_wait(file, &pf->rwait, wait);
 500         mask = POLLOUT | POLLWRNORM;
 501         if (skb_peek(&pf->rq) != 0)
 502                 mask |= POLLIN | POLLRDNORM;
 503         if (pf->dead)
 504                 mask |= POLLHUP;
 505         else if (pf->kind == INTERFACE) {
 506                 /* see comment in ppp_read */
 507                 struct ppp *ppp = PF_TO_PPP(pf);
 508                 if (ppp->n_channels == 0
 509                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 510                         mask |= POLLIN | POLLRDNORM;
 511         }
 512
 513         return mask;
 514 }
 515
 516 #ifdef CONFIG_PPP_FILTER
 517 static int get_filter(void __user *arg, struct sock_filter **p)
 518 {
 519         struct sock_fprog uprog;
 520         struct sock_filter *code = NULL;
 521         int len, err;
 522
 523         if (copy_from_user(&uprog, arg, sizeof(uprog)))
 524                 return -EFAULT;
 525
 526         if (uprog.len > BPF_MAXINSNS)
 527                 return -EINVAL;
 528
 529         if (!uprog.len) {
 530                 *p = NULL;
 531                 return 0;
 532         }
 533
 534         len = uprog.len * sizeof(struct sock_filter);
 535         code = kmalloc(len, GFP_KERNEL);
 536         if (code == NULL)
 537                 return -ENOMEM;
 538
 539         if (copy_from_user(code, uprog.filter, len)) {
 540                 kfree(code);
 541                 return -EFAULT;
 542         }
 543
 544         err = sk_chk_filter(code, uprog.len);
 545         if (err) {
 546                 kfree(code);
 547                 return err;
 548         }
 549
 550         *p = code;
 551         return uprog.len;
 552 }
 553 #endif /* CONFIG_PPP_FILTER */
 554
 555 static int ppp_ioctl(struct inode *inode, struct file *file,
 556                      unsigned int cmd, unsigned long arg)
 557 {
 558         struct ppp_file *pf = file->private_data;
 559         struct ppp *ppp;
 560         int err = -EFAULT, val, val2, i;
 561         struct ppp_idle idle;
 562         struct npioctl npi;
 563         int unit, cflags;
 564         struct slcompress *vj;
 565         void __user *argp = (void __user *)arg;
 566         int __user *p = argp;
 567
 568         if (pf == 0)
 569                 return ppp_unattached_ioctl(pf, file, cmd, arg);
 570
 571         if (cmd == PPPIOCDETACH) {
 572                 /*
 573                  * We have to be careful here... if the file descriptor
 574                  * has been dup'd, we could have another process in the
 575                  * middle of a poll using the same file *, so we had
 576                  * better not free the interface data structures -
 577                  * instead we fail the ioctl.  Even in this case, we
 578                  * shut down the interface if we are the owner of it.
 579                  * Actually, we should get rid of PPPIOCDETACH, userland
 580                  * (i.e. pppd) could achieve the same effect by closing
 581                  * this fd and reopening /dev/ppp.
 582                  */
 583                 err = -EINVAL;
 584                 if (pf->kind == INTERFACE) {
 585                         ppp = PF_TO_PPP(pf);
 586                         if (file == ppp->owner)
 587                                 ppp_shutdown_interface(ppp);
 588                 }
 589                 if (atomic_read(&file->f_count) <= 2) {
 590                         ppp_release(inode, file);
 591                         err = 0;
 592                 } else
 593                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%d\n",
 594                                atomic_read(&file->f_count));
 595                 return err;
 596         }
 597
 598         if (pf->kind == CHANNEL) {
 599                 struct channel *pch = PF_TO_CHANNEL(pf);
 600                 struct ppp_channel *chan;
 601
 602                 switch (cmd) {
 603                 case PPPIOCCONNECT:
 604                         if (get_user(unit, p))
 605                                 break;
 606                         err = ppp_connect_channel(pch, unit);
 607                         break;
 608
 609                 case PPPIOCDISCONN:
 610                         err = ppp_disconnect_channel(pch);
 611                         break;
 612
 613                 default:
 614                         down_read(&pch->chan_sem);
 615                         chan = pch->chan;
 616                         err = -ENOTTY;
 617                         if (chan && chan->ops->ioctl)
 618                                 err = chan->ops->ioctl(chan, cmd, arg);
 619                         up_read(&pch->chan_sem);
 620                 }
 621                 return err;
 622         }
 623
 624         if (pf->kind != INTERFACE) {
 625                 /* can't happen */
 626                 printk(KERN_ERR "PPP: not interface or channel??\n");
 627                 return -EINVAL;
 628         }
 629
 630         ppp = PF_TO_PPP(pf);
 631         switch (cmd) {
 632         case PPPIOCSMRU:
 633                 if (get_user(val, p))
 634                         break;
 635                 ppp->mru = val;
 636                 err = 0;
 637                 break;
 638
 639         case PPPIOCSFLAGS:
 640                 if (get_user(val, p))
 641                         break;
 642                 ppp_lock(ppp);
 643                 cflags = ppp->flags & ~val;
 644                 ppp->flags = val & SC_FLAG_BITS;
 645                 ppp_unlock(ppp);
 646                 if (cflags & SC_CCP_OPEN)
 647                         ppp_ccp_closed(ppp);
 648                 err = 0;
 649                 break;
 650
 651         case PPPIOCGFLAGS:
 652                 val = ppp->flags | ppp->xstate | ppp->rstate;
 653                 if (put_user(val, p))
 654                         break;
 655                 err = 0;
 656                 break;
 657
 658         case PPPIOCSCOMPRESS:
 659                 err = ppp_set_compress(ppp, arg);
 660                 break;
 661
 662         case PPPIOCGUNIT:
 663                 if (put_user(ppp->file.index, p))
 664                         break;
 665                 err = 0;
 666                 break;
 667
 668         case PPPIOCSDEBUG:
 669                 if (get_user(val, p))
 670                         break;
 671                 ppp->debug = val;
 672                 err = 0;
 673                 break;
 674
 675         case PPPIOCGDEBUG:
 676                 if (put_user(ppp->debug, p))
 677                         break;
 678                 err = 0;
 679                 break;
 680
 681         case PPPIOCGIDLE:
 682                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 683                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
 684                 if (copy_to_user(argp, &idle, sizeof(idle)))
 685                         break;
 686                 err = 0;
 687                 break;
 688
 689         case PPPIOCSMAXCID:
 690                 if (get_user(val, p))
 691                         break;
 692                 val2 = 15;
 693                 if ((val >> 16) != 0) {
 694                         val2 = val >> 16;
 695                         val &= 0xffff;
 696                 }
 697                 vj = slhc_init(val2+1, val+1);
 698                 if (vj == 0) {
 699                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
 700                         err = -ENOMEM;
 701                         break;
 702                 }
 703                 ppp_lock(ppp);
 704                 if (ppp->vj != 0)
 705                         slhc_free(ppp->vj);
 706                 ppp->vj = vj;
 707                 ppp_unlock(ppp);
 708                 err = 0;
 709                 break;
 710
 711         case PPPIOCGNPMODE:
 712         case PPPIOCSNPMODE:
 713                 if (copy_from_user(&npi, argp, sizeof(npi)))
 714                         break;
 715                 err = proto_to_npindex(npi.protocol);
 716                 if (err < 0)
 717                         break;
 718                 i = err;
 719                 if (cmd == PPPIOCGNPMODE) {
 720                         err = -EFAULT;
 721                         npi.mode = ppp->npmode[i];
 722                         if (copy_to_user(argp, &npi, sizeof(npi)))
 723                                 break;
 724                 } else {
 725                         ppp->npmode[i] = npi.mode;
 726                         /* we may be able to transmit more packets now (??) */
 727                         netif_wake_queue(ppp->dev);
 728                 }
 729                 err = 0;
 730                 break;
 731
 732 #ifdef CONFIG_PPP_FILTER
 733         case PPPIOCSPASS:
 734         {
 735                 struct sock_filter *code;
 736                 err = get_filter(argp, &code);
 737                 if (err >= 0) {
 738                         ppp_lock(ppp);
 739                         kfree(ppp->pass_filter);
 740                         ppp->pass_filter = code;
 741                         ppp->pass_len = err;
 742                         ppp_unlock(ppp);
 743                         err = 0;
 744                 }
 745                 break;
 746         }
 747         case PPPIOCSACTIVE:
 748         {
 749                 struct sock_filter *code;
 750                 err = get_filter(argp, &code);
 751                 if (err >= 0) {
 752                         ppp_lock(ppp);
 753                         kfree(ppp->active_filter);
 754                         ppp->active_filter = code;
 755                         ppp->active_len = err;
 756                         ppp_unlock(ppp);
 757                         err = 0;
 758                 }
 759                 break;
 760         }
 761 #endif /* CONFIG_PPP_FILTER */
 762
 763 #ifdef CONFIG_PPP_MULTILINK
 764         case PPPIOCSMRRU:
 765                 if (get_user(val, p))
 766                         break;
 767                 ppp_recv_lock(ppp);
 768                 ppp->mrru = val;
 769                 ppp_recv_unlock(ppp);
 770                 err = 0;
 771                 break;
 772 #endif /* CONFIG_PPP_MULTILINK */
 773
 774         default:
 775                 err = -ENOTTY;
 776         }
 777
 778         return err;
 779 }
 780
 781 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 782                                 unsigned int cmd, unsigned long arg)
 783 {
 784         int unit, err = -EFAULT;
 785         struct ppp *ppp;
 786         struct channel *chan;
 787         int __user *p = (int __user *)arg;
 788
 789         switch (cmd) {
 790         case PPPIOCNEWUNIT:
 791                 /* Create a new ppp unit */
 792                 if (get_user(unit, p))
 793                         break;
 794                 ppp = ppp_create_interface(unit, &err);
 795                 if (ppp == 0)
 796                         break;
 797                 file->private_data = &ppp->file;
 798                 ppp->owner = file;
 799                 err = -EFAULT;
 800                 if (put_user(ppp->file.index, p))
 801                         break;
 802                 err = 0;
 803                 break;
 804
 805         case PPPIOCATTACH:
 806                 /* Attach to an existing ppp unit */
 807                 if (get_user(unit, p))
 808                         break;
 809                 down(&all_ppp_sem);
 810                 err = -ENXIO;
 811                 ppp = ppp_find_unit(unit);
 812                 if (ppp != 0) {
 813                         atomic_inc(&ppp->file.refcnt);
 814                         file->private_data = &ppp->file;
 815                         err = 0;
 816                 }
 817                 up(&all_ppp_sem);
 818                 break;
 819
 820         case PPPIOCATTCHAN:
 821                 if (get_user(unit, p))
 822                         break;
 823                 spin_lock_bh(&all_channels_lock);
 824                 err = -ENXIO;
 825                 chan = ppp_find_channel(unit);
 826                 if (chan != 0) {
 827                         atomic_inc(&chan->file.refcnt);
 828                         file->private_data = &chan->file;
 829                         err = 0;
 830                 }
 831                 spin_unlock_bh(&all_channels_lock);
 832                 break;
 833
 834         default:
 835                 err = -ENOTTY;
 836         }
 837         return err;
 838 }
 839
 840 static struct file_operations ppp_device_fops = {
 841         .owner          = THIS_MODULE,
 842         .read           = ppp_read,
 843         .write          = ppp_write,
 844         .poll           = ppp_poll,
 845         .ioctl          = ppp_ioctl,
 846         .open           = ppp_open,
 847         .release        = ppp_release
 848 };
 849
 850 #define PPP_MAJOR       108
 851
 852 /* Called at boot time if ppp is compiled into the kernel,
 853    or at module load time (from init_module) if compiled as a module. */
 854 static int __init ppp_init(void)
 855 {
 856         int err;
 857
 858         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
 859         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
 860         if (!err) {
 861                 ppp_class = class_simple_create(THIS_MODULE, "ppp");
 862                 if (IS_ERR(ppp_class)) {
 863                         err = PTR_ERR(ppp_class);
 864                         goto out_chrdev;
 865                 }
 866                 class_simple_device_add(ppp_class, MKDEV(PPP_MAJOR, 0), NULL, "ppp");
 867                 err = devfs_mk_cdev(MKDEV(PPP_MAJOR, 0),
 868                                 S_IFCHR|S_IRUSR|S_IWUSR, "ppp");
 869                 if (err)
 870                         goto out_class;
 871         }
 872
 873 out:
 874         if (err)
 875                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
 876         return err;
 877
 878 out_class:
 879         class_simple_device_remove(MKDEV(PPP_MAJOR,0));
 880         class_simple_destroy(ppp_class);
 881 out_chrdev:
 882         unregister_chrdev(PPP_MAJOR, "ppp");
 883         goto out;
 884 }
 885
 886 /*
 887  * Network interface unit routines.
 888  */
 889 static int
 890 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 891 {
 892         struct ppp *ppp = (struct ppp *) dev->priv;
 893         int npi, proto;
 894         unsigned char *pp;
 895
 896         npi = ethertype_to_npindex(ntohs(skb->protocol));
 897         if (npi < 0)
 898                 goto outf;
 899
 900         /* Drop, accept or reject the packet */
 901         switch (ppp->npmode[npi]) {
 902         case NPMODE_PASS:
 903                 break;
 904         case NPMODE_QUEUE:
 905                 /* it would be nice to have a way to tell the network
 906                    system to queue this one up for later. */
 907                 goto outf;
 908         case NPMODE_DROP:
 909         case NPMODE_ERROR:
 910                 goto outf;
 911         }
 912
 913         /* Put the 2-byte PPP protocol number on the front,
 914            making sure there is room for the address and control fields. */
 915         if (skb_headroom(skb) < PPP_HDRLEN) {
 916                 struct sk_buff *ns;
 917
 918                 ns = alloc_skb(skb->len + dev->hard_header_len, GFP_ATOMIC);
 919                 if (ns == 0)
 920                         goto outf;
 921                 skb_reserve(ns, dev->hard_header_len);
 922                 skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
 923                 kfree_skb(skb);
 924                 skb = ns;
 925         }
 926         pp = skb_push(skb, 2);
 927         proto = npindex_to_proto[npi];
 928         pp[0] = proto >> 8;
 929         pp[1] = proto;
 930
 931         netif_stop_queue(dev);
 932         skb_queue_tail(&ppp->file.xq, skb);
 933         ppp_xmit_process(ppp);
 934         return 0;
 935
 936  outf:
 937         kfree_skb(skb);
 938         ++ppp->stats.tx_dropped;
 939         return 0;
 940 }
 941
 942 static struct net_device_stats *
 943 ppp_net_stats(struct net_device *dev)
 944 {
 945         struct ppp *ppp = (struct ppp *) dev->priv;
 946
 947         return &ppp->stats;
 948 }
 949
 950 static int
 951 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 952 {
 953         struct ppp *ppp = dev->priv;
 954         int err = -EFAULT;
 955         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
 956         struct ppp_stats stats;
 957         struct ppp_comp_stats cstats;
 958         char *vers;
 959
 960         switch (cmd) {
 961         case SIOCGPPPSTATS:
 962                 ppp_get_stats(ppp, &stats);
 963                 if (copy_to_user(addr, &stats, sizeof(stats)))
 964                         break;
 965                 err = 0;
 966                 break;
 967
 968         case SIOCGPPPCSTATS:
 969                 memset(&cstats, 0, sizeof(cstats));
 970                 if (ppp->xc_state != 0)
 971                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
 972                 if (ppp->rc_state != 0)
 973                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
 974                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
 975                         break;
 976                 err = 0;
 977                 break;
 978
 979         case SIOCGPPPVER:
 980                 vers = PPP_VERSION;
 981                 if (copy_to_user(addr, vers, strlen(vers) + 1))
 982                         break;
 983                 err = 0;
 984                 break;
 985
 986         default:
 987                 err = -EINVAL;
 988         }
 989
 990         return err;
 991 }
 992
 993 static void ppp_setup(struct net_device *dev)
 994 {
 995         dev->hard_header_len = PPP_HDRLEN;
 996         dev->mtu = PPP_MTU;
 997         dev->addr_len = 0;
 998         dev->tx_queue_len = 3;
 999         dev->type = ARPHRD_PPP;
1000         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1001 }
1002
1003 /*
1004  * Transmit-side routines.
1005  */
1006
1007 /*
1008  * Called to do any work queued up on the transmit side
1009  * that can now be done.
1010  */
1011 static void
1012 ppp_xmit_process(struct ppp *ppp)
1013 {
1014         struct sk_buff *skb;
1015
1016         ppp_xmit_lock(ppp);
1017         if (ppp->dev != 0) {
1018                 ppp_push(ppp);
1019                 while (ppp->xmit_pending == 0
1020                        && (skb = skb_dequeue(&ppp->file.xq)) != 0)
1021                         ppp_send_frame(ppp, skb);
1022                 /* If there's no work left to do, tell the core net
1023                    code that we can accept some more. */
1024                 if (ppp->xmit_pending == 0 && skb_peek(&ppp->file.xq) == 0)
1025                         netif_wake_queue(ppp->dev);
1026         }
1027         ppp_xmit_unlock(ppp);
1028 }
1029
1030 /*
1031  * Compress and send a frame.
1032  * The caller should have locked the xmit path,
1033  * and xmit_pending should be 0.
1034  */
1035 static void
1036 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1037 {
1038         int proto = PPP_PROTO(skb);
1039         struct sk_buff *new_skb;
1040         int len;
1041         unsigned char *cp;
1042
1043         if (proto < 0x8000) {
1044 #ifdef CONFIG_PPP_FILTER
1045                 /* check if we should pass this packet */
1046                 /* the filter instructions are constructed assuming
1047                    a four-byte PPP header on each packet */
1048                 *skb_push(skb, 2) = 1;
1049                 if (ppp->pass_filter
1050                     && sk_run_filter(skb, ppp->pass_filter,
1051                                      ppp->pass_len) == 0) {
1052                         if (ppp->debug & 1)
1053                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1054                         kfree_skb(skb);
1055                         return;
1056                 }
1057                 /* if this packet passes the active filter, record the time */
1058                 if (!(ppp->active_filter
1059                       && sk_run_filter(skb, ppp->active_filter,
1060                                        ppp->active_len) == 0))
1061                         ppp->last_xmit = jiffies;
1062                 skb_pull(skb, 2);
1063 #else
1064                 /* for data packets, record the time */
1065                 ppp->last_xmit = jiffies;
1066 #endif /* CONFIG_PPP_FILTER */
1067         }
1068
1069         ++ppp->stats.tx_packets;
1070         ppp->stats.tx_bytes += skb->len - 2;
1071
1072         switch (proto) {
1073         case PPP_IP:
1074                 if (ppp->vj == 0 || (ppp->flags & SC_COMP_TCP) == 0)
1075                         break;
1076                 /* try to do VJ TCP header compression */
1077                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1078                                     GFP_ATOMIC);
1079                 if (new_skb == 0) {
1080                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1081                         goto drop;
1082                 }
1083                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1084                 cp = skb->data + 2;
1085                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1086                                     new_skb->data + 2, &cp,
1087                                     !(ppp->flags & SC_NO_TCP_CCID));
1088                 if (cp == skb->data + 2) {
1089                         /* didn't compress */
1090                         kfree_skb(new_skb);
1091                 } else {
1092                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1093                                 proto = PPP_VJC_COMP;
1094                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1095                         } else {
1096                                 proto = PPP_VJC_UNCOMP;
1097                                 cp[0] = skb->data[2];
1098                         }
1099                         kfree_skb(skb);
1100                         skb = new_skb;
1101                         cp = skb_put(skb, len + 2);
1102                         cp[0] = 0;
1103                         cp[1] = proto;
1104                 }
1105                 break;
1106
1107         case PPP_CCP:
1108                 /* peek at outbound CCP frames */
1109                 ppp_ccp_peek(ppp, skb, 0);
1110                 break;
1111         }
1112
1113         /* try to do packet compression */
1114         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0
1115             && proto != PPP_LCP && proto != PPP_CCP) {
1116                 new_skb = alloc_skb(ppp->dev->mtu + ppp->dev->hard_header_len,
1117                                     GFP_ATOMIC);
1118                 if (new_skb == 0) {
1119                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1120                         goto drop;
1121                 }
1122                 if (ppp->dev->hard_header_len > PPP_HDRLEN)
1123                         skb_reserve(new_skb,
1124                                     ppp->dev->hard_header_len - PPP_HDRLEN);
1125
1126                 /* compressor still expects A/C bytes in hdr */
1127                 len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1128                                            new_skb->data, skb->len + 2,
1129                                            ppp->dev->mtu + PPP_HDRLEN);
1130                 if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1131                         kfree_skb(skb);
1132                         skb = new_skb;
1133                         skb_put(skb, len);
1134                         skb_pull(skb, 2);       /* pull off A/C bytes */
1135                 } else {
1136                         /* didn't compress, or CCP not up yet */
1137                         kfree_skb(new_skb);
1138                 }
1139         }
1140
1141         /*
1142          * If we are waiting for traffic (demand dialling),
1143          * queue it up for pppd to receive.
1144          */
1145         if (ppp->flags & SC_LOOP_TRAFFIC) {
1146                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1147                         goto drop;
1148                 skb_queue_tail(&ppp->file.rq, skb);
1149                 wake_up_interruptible(&ppp->file.rwait);
1150                 return;
1151         }
1152
1153         ppp->xmit_pending = skb;
1154         ppp_push(ppp);
1155         return;
1156
1157  drop:
1158         kfree_skb(skb);
1159         ++ppp->stats.tx_errors;
1160 }
1161
1162 /*
1163  * Try to send the frame in xmit_pending.
1164  * The caller should have the xmit path locked.
1165  */
1166 static void
1167 ppp_push(struct ppp *ppp)
1168 {
1169         struct list_head *list;
1170         struct channel *pch;
1171         struct sk_buff *skb = ppp->xmit_pending;
1172
1173         if (skb == 0)
1174                 return;
1175
1176         list = &ppp->channels;
1177         if (list_empty(list)) {
1178                 /* nowhere to send the packet, just drop it */
1179                 ppp->xmit_pending = NULL;
1180                 kfree_skb(skb);
1181                 return;
1182         }
1183
1184         if ((ppp->flags & SC_MULTILINK) == 0) {
1185                 /* not doing multilink: send it down the first channel */
1186                 list = list->next;
1187                 pch = list_entry(list, struct channel, clist);
1188
1189                 spin_lock_bh(&pch->downl);
1190                 if (pch->chan) {
1191                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1192                                 ppp->xmit_pending = NULL;
1193                 } else {
1194                         /* channel got unregistered */
1195                         kfree_skb(skb);
1196                         ppp->xmit_pending = NULL;
1197                 }
1198                 spin_unlock_bh(&pch->downl);
1199                 return;
1200         }
1201
1202 #ifdef CONFIG_PPP_MULTILINK
1203         /* Multilink: fragment the packet over as many links
1204            as can take the packet at the moment. */
1205         if (!ppp_mp_explode(ppp, skb))
1206                 return;
1207 #endif /* CONFIG_PPP_MULTILINK */
1208
1209         ppp->xmit_pending = NULL;
1210         kfree_skb(skb);
1211 }
1212
1213 #ifdef CONFIG_PPP_MULTILINK
1214 /*
1215  * Divide a packet to be transmitted into fragments and
1216  * send them out the individual links.
1217  */
1218 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1219 {
1220         int len, fragsize;
1221         int i, bits, hdrlen, mtu;
1222         int flen;
1223         int navail, nfree;
1224         int nbigger;
1225         unsigned char *p, *q;
1226         struct list_head *list;
1227         struct channel *pch;
1228         struct sk_buff *frag;
1229         struct ppp_channel *chan;
1230
1231         nfree = 0;      /* # channels which have no packet already queued */
1232         navail = 0;     /* total # of usable channels (not deregistered) */
1233         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1234         i = 0;
1235         list = &ppp->channels;
1236         while ((list = list->next) != &ppp->channels) {
1237                 pch = list_entry(list, struct channel, clist);
1238                 navail += pch->avail = (pch->chan != NULL);
1239                 if (pch->avail) {
1240                         if (skb_queue_len(&pch->file.xq) == 0
1241                             || !pch->had_frag) {
1242                                 pch->avail = 2;
1243                                 ++nfree;
1244                         }
1245                         if (!pch->had_frag && i < ppp->nxchan)
1246                                 ppp->nxchan = i;
1247                 }
1248                 ++i;
1249         }
1250
1251         /*
1252          * Don't start sending this packet unless at least half of
1253          * the channels are free.  This gives much better TCP
1254          * performance if we have a lot of channels.
1255          */
1256         if (nfree == 0 || nfree < navail / 2)
1257                 return 0;       /* can't take now, leave it in xmit_pending */
1258
1259         /* Do protocol field compression (XXX this should be optional) */
1260         p = skb->data;
1261         len = skb->len;
1262         if (*p == 0) {
1263                 ++p;
1264                 --len;
1265         }
1266
1267         /*
1268          * Decide on fragment size.
1269          * We create a fragment for each free channel regardless of
1270          * how small they are (i.e. even 0 length) in order to minimize
1271          * the time that it will take to detect when a channel drops
1272          * a fragment.
1273          */
1274         fragsize = len;
1275         if (nfree > 1)
1276                 fragsize = ROUNDUP(fragsize, nfree);
1277         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1278            except if nbigger==0, then they all get fragsize. */
1279         nbigger = len % nfree;
1280
1281         /* skip to the channel after the one we last used
1282            and start at that one */
1283         for (i = 0; i < ppp->nxchan; ++i) {
1284                 list = list->next;
1285                 if (list == &ppp->channels) {
1286                         i = 0;
1287                         break;
1288                 }
1289         }
1290
1291         /* create a fragment for each channel */
1292         bits = B;
1293         while (nfree > 0 || len > 0) {
1294                 list = list->next;
1295                 if (list == &ppp->channels) {
1296                         i = 0;
1297                         continue;
1298                 }
1299                 pch = list_entry(list, struct channel, clist);
1300                 ++i;
1301                 if (!pch->avail)
1302                         continue;
1303
1304                 /*
1305                  * Skip this channel if it has a fragment pending already and
1306                  * we haven't given a fragment to all of the free channels.
1307                  */
1308                 if (pch->avail == 1) {
1309                         if (nfree > 0)
1310                                 continue;
1311                 } else {
1312                         --nfree;
1313                         pch->avail = 1;
1314                 }
1315
1316                 /* check the channel's mtu and whether it is still attached. */
1317                 spin_lock_bh(&pch->downl);
1318                 if (pch->chan == NULL) {
1319                         /* can't use this channel, it's being deregistered */
1320                         spin_unlock_bh(&pch->downl);
1321                         pch->avail = 0;
1322                         if (--navail == 0)
1323                                 break;
1324                         continue;
1325                 }
1326
1327                 /*
1328                  * Create a fragment for this channel of
1329                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1330                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1331                  * MTU, so we use mtu = 2 + hdrlen.
1332                  */
1333                 if (fragsize > len)
1334                         fragsize = len;
1335                 flen = fragsize;
1336                 mtu = pch->chan->mtu + 2 - hdrlen;
1337                 if (mtu < 4)
1338                         mtu = 4;
1339                 if (flen > mtu)
1340                         flen = mtu;
1341                 if (flen == len && nfree == 0)
1342                         bits |= E;
1343                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1344                 if (frag == 0)
1345                         goto noskb;
1346                 q = skb_put(frag, flen + hdrlen);
1347
1348                 /* make the MP header */
1349                 q[0] = PPP_MP >> 8;
1350                 q[1] = PPP_MP;
1351                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1352                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1353                         q[3] = ppp->nxseq;
1354                 } else {
1355                         q[2] = bits;
1356                         q[3] = ppp->nxseq >> 16;
1357                         q[4] = ppp->nxseq >> 8;
1358                         q[5] = ppp->nxseq;
1359                 }
1360
1361                 /*
1362                  * Copy the data in.
1363                  * Unfortunately there is a bug in older versions of
1364                  * the Linux PPP multilink reconstruction code where it
1365                  * drops 0-length fragments.  Therefore we make sure the
1366                  * fragment has at least one byte of data.  Any bytes
1367                  * we add in this situation will end up as padding on the
1368                  * end of the reconstructed packet.
1369                  */
1370                 if (flen == 0)
1371                         *skb_put(frag, 1) = 0;
1372                 else
1373                         memcpy(q + hdrlen, p, flen);
1374
1375                 /* try to send it down the channel */
1376                 chan = pch->chan;
1377                 if (skb_queue_len(&pch->file.xq)
1378                     || !chan->ops->start_xmit(chan, frag))
1379                         skb_queue_tail(&pch->file.xq, frag);
1380                 pch->had_frag = 1;
1381                 p += flen;
1382                 len -= flen;
1383                 ++ppp->nxseq;
1384                 bits = 0;
1385                 spin_unlock_bh(&pch->downl);
1386
1387                 if (--nbigger == 0 && fragsize > 0)
1388                         --fragsize;
1389         }
1390         ppp->nxchan = i;
1391
1392         return 1;
1393
1394  noskb:
1395         spin_unlock_bh(&pch->downl);
1396         if (ppp->debug & 1)
1397                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1398         ++ppp->stats.tx_errors;
1399         ++ppp->nxseq;
1400         return 1;       /* abandon the frame */
1401 }
1402 #endif /* CONFIG_PPP_MULTILINK */
1403
1404 /*
1405  * Try to send data out on a channel.
1406  */
1407 static void
1408 ppp_channel_push(struct channel *pch)
1409 {
1410         struct sk_buff *skb;
1411         struct ppp *ppp;
1412
1413         spin_lock_bh(&pch->downl);
1414         if (pch->chan != 0) {
1415                 while (skb_queue_len(&pch->file.xq) > 0) {
1416                         skb = skb_dequeue(&pch->file.xq);
1417                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1418                                 /* put the packet back and try again later */
1419                                 skb_queue_head(&pch->file.xq, skb);
1420                                 break;
1421                         }
1422                 }
1423         } else {
1424                 /* channel got deregistered */
1425                 skb_queue_purge(&pch->file.xq);
1426         }
1427         spin_unlock_bh(&pch->downl);
1428         /* see if there is anything from the attached unit to be sent */
1429         if (skb_queue_len(&pch->file.xq) == 0) {
1430                 read_lock_bh(&pch->upl);
1431                 ppp = pch->ppp;
1432                 if (ppp != 0)
1433                         ppp_xmit_process(ppp);
1434                 read_unlock_bh(&pch->upl);
1435         }
1436 }
1437
1438 /*
1439  * Receive-side routines.
1440  */
1441
1442 /* misuse a few fields of the skb for MP reconstruction */
1443 #define sequence        priority
1444 #define BEbits          cb[0]
1445
1446 static inline void
1447 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1448 {
1449         ppp_recv_lock(ppp);
1450         /* ppp->dev == 0 means interface is closing down */
1451         if (ppp->dev != 0)
1452                 ppp_receive_frame(ppp, skb, pch);
1453         else
1454                 kfree_skb(skb);
1455         ppp_recv_unlock(ppp);
1456 }
1457
1458 void
1459 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1460 {
1461         struct channel *pch = chan->ppp;
1462         int proto;
1463
1464         if (pch == 0 || skb->len == 0) {
1465                 kfree_skb(skb);
1466                 return;
1467         }
1468
1469         proto = PPP_PROTO(skb);
1470         read_lock_bh(&pch->upl);
1471         if (pch->ppp == 0 || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1472                 /* put it on the channel queue */
1473                 skb_queue_tail(&pch->file.rq, skb);
1474                 /* drop old frames if queue too long */
1475                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1476                        && (skb = skb_dequeue(&pch->file.rq)) != 0)
1477                         kfree_skb(skb);
1478                 wake_up_interruptible(&pch->file.rwait);
1479         } else {
1480                 ppp_do_recv(pch->ppp, skb, pch);
1481         }
1482         read_unlock_bh(&pch->upl);
1483 }
1484
1485 /* Put a 0-length skb in the receive queue as an error indication */
1486 void
1487 ppp_input_error(struct ppp_channel *chan, int code)
1488 {
1489         struct channel *pch = chan->ppp;
1490         struct sk_buff *skb;
1491
1492         if (pch == 0)
1493                 return;
1494
1495         read_lock_bh(&pch->upl);
1496         if (pch->ppp != 0) {
1497                 skb = alloc_skb(0, GFP_ATOMIC);
1498                 if (skb != 0) {
1499                         skb->len = 0;           /* probably unnecessary */
1500                         skb->cb[0] = code;
1501                         ppp_do_recv(pch->ppp, skb, pch);
1502                 }
1503         }
1504         read_unlock_bh(&pch->upl);
1505 }
1506
1507 /*
1508  * We come in here to process a received frame.
1509  * The receive side of the ppp unit is locked.
1510  */
1511 static void
1512 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1513 {
1514         if (skb->len >= 2) {
1515 #ifdef CONFIG_PPP_MULTILINK
1516                 /* XXX do channel-level decompression here */
1517                 if (PPP_PROTO(skb) == PPP_MP)
1518                         ppp_receive_mp_frame(ppp, skb, pch);
1519                 else
1520 #endif /* CONFIG_PPP_MULTILINK */
1521                         ppp_receive_nonmp_frame(ppp, skb);
1522                 return;
1523         }
1524
1525         if (skb->len > 0)
1526                 /* note: a 0-length skb is used as an error indication */
1527                 ++ppp->stats.rx_length_errors;
1528
1529         kfree_skb(skb);
1530         ppp_receive_error(ppp);
1531 }
1532
1533 static void
1534 ppp_receive_error(struct ppp *ppp)
1535 {
1536         ++ppp->stats.rx_errors;
1537         if (ppp->vj != 0)
1538                 slhc_toss(ppp->vj);
1539 }
1540
1541 static void
1542 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1543 {
1544         struct sk_buff *ns;
1545         int proto, len, npi;
1546
1547         /*
1548          * Decompress the frame, if compressed.
1549          * Note that some decompressors need to see uncompressed frames
1550          * that come in as well as compressed frames.
1551          */
1552         if (ppp->rc_state != 0 && (ppp->rstate & SC_DECOMP_RUN)
1553             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1554                 skb = ppp_decompress_frame(ppp, skb);
1555
1556         proto = PPP_PROTO(skb);
1557         switch (proto) {
1558         case PPP_VJC_COMP:
1559                 /* decompress VJ compressed packets */
1560                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1561                         goto err;
1562
1563                 if (skb_tailroom(skb) < 124) {
1564                         /* copy to a new sk_buff with more tailroom */
1565                         ns = dev_alloc_skb(skb->len + 128);
1566                         if (ns == 0) {
1567                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1568                                 goto err;
1569                         }
1570                         skb_reserve(ns, 2);
1571                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1572                         kfree_skb(skb);
1573                         skb = ns;
1574                 }
1575                 else if (!pskb_may_pull(skb, skb->len))
1576                         goto err;
1577
1578                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1579                 if (len <= 0) {
1580                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1581                         goto err;
1582                 }
1583                 len += 2;
1584                 if (len > skb->len)
1585                         skb_put(skb, len - skb->len);
1586                 else if (len < skb->len)
1587                         skb_trim(skb, len);
1588                 proto = PPP_IP;
1589                 break;
1590
1591         case PPP_VJC_UNCOMP:
1592                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1593                         goto err;
1594
1595                 /* Until we fix the decompressor need to make sure
1596                  * data portion is linear.
1597                  */
1598                 if (!pskb_may_pull(skb, skb->len))
1599                         goto err;
1600
1601                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1602                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1603                         goto err;
1604                 }
1605                 proto = PPP_IP;
1606                 break;
1607
1608         case PPP_CCP:
1609                 ppp_ccp_peek(ppp, skb, 1);
1610                 break;
1611         }
1612
1613         ++ppp->stats.rx_packets;
1614         ppp->stats.rx_bytes += skb->len - 2;
1615
1616         npi = proto_to_npindex(proto);
1617         if (npi < 0) {
1618                 /* control or unknown frame - pass it to pppd */
1619                 skb_queue_tail(&ppp->file.rq, skb);
1620                 /* limit queue length by dropping old frames */
1621                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1622                        && (skb = skb_dequeue(&ppp->file.rq)) != 0)
1623                         kfree_skb(skb);
1624                 /* wake up any process polling or blocking on read */
1625                 wake_up_interruptible(&ppp->file.rwait);
1626
1627         } else {
1628                 /* network protocol frame - give it to the kernel */
1629
1630 #ifdef CONFIG_PPP_FILTER
1631                 /* check if the packet passes the pass and active filters */
1632                 /* the filter instructions are constructed assuming
1633                    a four-byte PPP header on each packet */
1634                 *skb_push(skb, 2) = 0;
1635                 if (ppp->pass_filter
1636                     && sk_run_filter(skb, ppp->pass_filter,
1637                                      ppp->pass_len) == 0) {
1638                         if (ppp->debug & 1)
1639                                 printk(KERN_DEBUG "PPP: inbound frame not passed\n");
1640                         kfree_skb(skb);
1641                         return;
1642                 }
1643                 if (!(ppp->active_filter
1644                       && sk_run_filter(skb, ppp->active_filter,
1645                                        ppp->active_len) == 0))
1646                         ppp->last_recv = jiffies;
1647                 skb_pull(skb, 2);
1648 #else
1649                 ppp->last_recv = jiffies;
1650 #endif /* CONFIG_PPP_FILTER */
1651
1652                 if ((ppp->dev->flags & IFF_UP) == 0
1653                     || ppp->npmode[npi] != NPMODE_PASS) {
1654                         kfree_skb(skb);
1655                 } else {
1656                         skb_pull(skb, 2);       /* chop off protocol */
1657                         skb->dev = ppp->dev;
1658                         skb->protocol = htons(npindex_to_ethertype[npi]);
1659                         skb->mac.raw = skb->data;
1660                         skb->input_dev = ppp->dev;
1661                         netif_rx(skb);
1662                         ppp->dev->last_rx = jiffies;
1663                 }
1664         }
1665         return;
1666
1667  err:
1668         kfree_skb(skb);
1669         ppp_receive_error(ppp);
1670 }
1671
1672 static struct sk_buff *
1673 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1674 {
1675         int proto = PPP_PROTO(skb);
1676         struct sk_buff *ns;
1677         int len;
1678
1679         /* Until we fix all the decompressor's need to make sure
1680          * data portion is linear.
1681          */
1682         if (!pskb_may_pull(skb, skb->len))
1683                 goto err;
1684
1685         if (proto == PPP_COMP) {
1686                 ns = dev_alloc_skb(ppp->mru + PPP_HDRLEN);
1687                 if (ns == 0) {
1688                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1689                         goto err;
1690                 }
1691                 /* the decompressor still expects the A/C bytes in the hdr */
1692                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1693                                 skb->len + 2, ns->data, ppp->mru + PPP_HDRLEN);
1694                 if (len < 0) {
1695                         /* Pass the compressed frame to pppd as an
1696                            error indication. */
1697                         if (len == DECOMP_FATALERROR)
1698                                 ppp->rstate |= SC_DC_FERROR;
1699                         kfree_skb(ns);
1700                         goto err;
1701                 }
1702
1703                 kfree_skb(skb);
1704                 skb = ns;
1705                 skb_put(skb, len);
1706                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1707
1708         } else {
1709                 /* Uncompressed frame - pass to decompressor so it
1710                    can update its dictionary if necessary. */
1711                 if (ppp->rcomp->incomp)
1712                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1713                                            skb->len + 2);
1714         }
1715
1716         return skb;
1717
1718  err:
1719         ppp->rstate |= SC_DC_ERROR;
1720         ppp_receive_error(ppp);
1721         return skb;
1722 }
1723
1724 #ifdef CONFIG_PPP_MULTILINK
1725 /*
1726  * Receive a multilink frame.
1727  * We put it on the reconstruction queue and then pull off
1728  * as many completed frames as we can.
1729  */
1730 static void
1731 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1732 {
1733         u32 mask, seq;
1734         struct list_head *l;
1735         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1736
1737         if (!pskb_may_pull(skb, mphdrlen) || ppp->mrru == 0)
1738                 goto err;               /* no good, throw it away */
1739
1740         /* Decode sequence number and begin/end bits */
1741         if (ppp->flags & SC_MP_SHORTSEQ) {
1742                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1743                 mask = 0xfff;
1744         } else {
1745                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1746                 mask = 0xffffff;
1747         }
1748         skb->BEbits = skb->data[2];
1749         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1750
1751         /*
1752          * Do protocol ID decompression on the first fragment of each packet.
1753          */
1754         if ((skb->BEbits & B) && (skb->data[0] & 1))
1755                 *skb_push(skb, 1) = 0;
1756
1757         /*
1758          * Expand sequence number to 32 bits, making it as close
1759          * as possible to ppp->minseq.
1760          */
1761         seq |= ppp->minseq & ~mask;
1762         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1763                 seq += mask + 1;
1764         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1765                 seq -= mask + 1;        /* should never happen */
1766         skb->sequence = seq;
1767         pch->lastseq = seq;
1768
1769         /*
1770          * If this packet comes before the next one we were expecting,
1771          * drop it.
1772          */
1773         if (seq_before(seq, ppp->nextseq)) {
1774                 kfree_skb(skb);
1775                 ++ppp->stats.rx_dropped;
1776                 ppp_receive_error(ppp);
1777                 return;
1778         }
1779
1780         /*
1781          * Reevaluate minseq, the minimum over all channels of the
1782          * last sequence number received on each channel.  Because of
1783          * the increasing sequence number rule, we know that any fragment
1784          * before `minseq' which hasn't arrived is never going to arrive.
1785          * The list of channels can't change because we have the receive
1786          * side of the ppp unit locked.
1787          */
1788         for (l = ppp->channels.next; l != &ppp->channels; l = l->next) {
1789                 struct channel *ch = list_entry(l, struct channel, clist);
1790                 if (seq_before(ch->lastseq, seq))
1791                         seq = ch->lastseq;
1792         }
1793         if (seq_before(ppp->minseq, seq))
1794                 ppp->minseq = seq;
1795
1796         /* Put the fragment on the reconstruction queue */
1797         ppp_mp_insert(ppp, skb);
1798
1799         /* If the queue is getting long, don't wait any longer for packets
1800            before the start of the queue. */
1801         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN
1802             && seq_before(ppp->minseq, ppp->mrq.next->sequence))
1803                 ppp->minseq = ppp->mrq.next->sequence;
1804
1805         /* Pull completed packets off the queue and receive them. */
1806         while ((skb = ppp_mp_reconstruct(ppp)) != 0)
1807                 ppp_receive_nonmp_frame(ppp, skb);
1808
1809         return;
1810
1811  err:
1812         kfree_skb(skb);
1813         ppp_receive_error(ppp);
1814 }
1815
1816 /*
1817  * Insert a fragment on the MP reconstruction queue.
1818  * The queue is ordered by increasing sequence number.
1819  */
1820 static void
1821 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1822 {
1823         struct sk_buff *p;
1824         struct sk_buff_head *list = &ppp->mrq;
1825         u32 seq = skb->sequence;
1826
1827         /* N.B. we don't need to lock the list lock because we have the
1828            ppp unit receive-side lock. */
1829         for (p = list->next; p != (struct sk_buff *)list; p = p->next)
1830                 if (seq_before(seq, p->sequence))
1831                         break;
1832         __skb_insert(skb, p->prev, p, list);
1833 }
1834
1835 /*
1836  * Reconstruct a packet from the MP fragment queue.
1837  * We go through increasing sequence numbers until we find a
1838  * complete packet, or we get to the sequence number for a fragment
1839  * which hasn't arrived but might still do so.
1840  */
1841 struct sk_buff *
1842 ppp_mp_reconstruct(struct ppp *ppp)
1843 {
1844         u32 seq = ppp->nextseq;
1845         u32 minseq = ppp->minseq;
1846         struct sk_buff_head *list = &ppp->mrq;
1847         struct sk_buff *p, *next;
1848         struct sk_buff *head, *tail;
1849         struct sk_buff *skb = NULL;
1850         int lost = 0, len = 0;
1851
1852         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1853                 return NULL;
1854         head = list->next;
1855         tail = NULL;
1856         for (p = head; p != (struct sk_buff *) list; p = next) {
1857                 next = p->next;
1858                 if (seq_before(p->sequence, seq)) {
1859                         /* this can't happen, anyway ignore the skb */
1860                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1861                                p->sequence, seq);
1862                         head = next;
1863                         continue;
1864                 }
1865                 if (p->sequence != seq) {
1866                         /* Fragment `seq' is missing.  If it is after
1867                            minseq, it might arrive later, so stop here. */
1868                         if (seq_after(seq, minseq))
1869                                 break;
1870                         /* Fragment `seq' is lost, keep going. */
1871                         lost = 1;
1872                         seq = seq_before(minseq, p->sequence)?
1873                                 minseq + 1: p->sequence;
1874                         next = p;
1875                         continue;
1876                 }
1877
1878                 /*
1879                  * At this point we know that all the fragments from
1880                  * ppp->nextseq to seq are either present or lost.
1881                  * Also, there are no complete packets in the queue
1882                  * that have no missing fragments and end before this
1883                  * fragment.
1884                  */
1885
1886                 /* B bit set indicates this fragment starts a packet */
1887                 if (p->BEbits & B) {
1888                         head = p;
1889                         lost = 0;
1890                         len = 0;
1891                 }
1892
1893                 len += p->len;
1894
1895                 /* Got a complete packet yet? */
1896                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1897                         if (len > ppp->mrru + 2) {
1898                                 ++ppp->stats.rx_length_errors;
1899                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1900                                        " is too long (%d)\n", len);
1901                         } else if (p == head) {
1902                                 /* fragment is complete packet - reuse skb */
1903                                 tail = p;
1904                                 skb = skb_get(p);
1905                                 break;
1906                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1907                                 ++ppp->stats.rx_missed_errors;
1908                                 printk(KERN_DEBUG "PPP: no memory for "
1909                                        "reconstructed packet");
1910                         } else {
1911                                 tail = p;
1912                                 break;
1913                         }
1914                         ppp->nextseq = seq + 1;
1915                 }
1916
1917                 /*
1918                  * If this is the ending fragment of a packet,
1919                  * and we haven't found a complete valid packet yet,
1920                  * we can discard up to and including this fragment.
1921                  */
1922                 if (p->BEbits & E)
1923                         head = next;
1924
1925                 ++seq;
1926         }
1927
1928         /* If we have a complete packet, copy it all into one skb. */
1929         if (tail != NULL) {
1930                 /* If we have discarded any fragments,
1931                    signal a receive error. */
1932                 if (head->sequence != ppp->nextseq) {
1933                         if (ppp->debug & 1)
1934                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1935                                        ppp->nextseq, head->sequence-1);
1936                         ++ppp->stats.rx_dropped;
1937                         ppp_receive_error(ppp);
1938                 }
1939
1940                 if (head != tail)
1941                         /* copy to a single skb */
1942                         for (p = head; p != tail->next; p = p->next)
1943                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1944                 ppp->nextseq = tail->sequence + 1;
1945                 head = tail->next;
1946         }
1947
1948         /* Discard all the skbuffs that we have copied the data out of
1949            or that we can't use. */
1950         while ((p = list->next) != head) {
1951                 __skb_unlink(p, list);
1952                 kfree_skb(p);
1953         }
1954
1955         return skb;
1956 }
1957 #endif /* CONFIG_PPP_MULTILINK */
1958
1959 /*
1960  * Channel interface.
1961  */
1962
1963 /*
1964  * Create a new, unattached ppp channel.
1965  */
1966 int
1967 ppp_register_channel(struct ppp_channel *chan)
1968 {
1969         struct channel *pch;
1970
1971         pch = kmalloc(sizeof(struct channel), GFP_KERNEL);
1972         if (pch == 0)
1973                 return -ENOMEM;
1974         memset(pch, 0, sizeof(struct channel));
1975         pch->ppp = NULL;
1976         pch->chan = chan;
1977         chan->ppp = pch;
1978         init_ppp_file(&pch->file, CHANNEL);
1979         pch->file.hdrlen = chan->hdrlen;
1980 #ifdef CONFIG_PPP_MULTILINK
1981         pch->lastseq = -1;
1982 #endif /* CONFIG_PPP_MULTILINK */
1983         init_rwsem(&pch->chan_sem);
1984         spin_lock_init(&pch->downl);
1985         rwlock_init(&pch->upl);
1986         spin_lock_bh(&all_channels_lock);
1987         pch->file.index = ++last_channel_index;
1988         list_add(&pch->list, &new_channels);
1989         atomic_inc(&channel_count);
1990         spin_unlock_bh(&all_channels_lock);
1991         return 0;
1992 }
1993
1994 /*
1995  * Return the index of a channel.
1996  */
1997 int ppp_channel_index(struct ppp_channel *chan)
1998 {
1999         struct channel *pch = chan->ppp;
2000
2001         if (pch != 0)
2002                 return pch->file.index;
2003         return -1;
2004 }
2005
2006 /*
2007  * Return the PPP unit number to which a channel is connected.
2008  */
2009 int ppp_unit_number(struct ppp_channel *chan)
2010 {
2011         struct channel *pch = chan->ppp;
2012         int unit = -1;
2013
2014         if (pch != 0) {
2015                 read_lock_bh(&pch->upl);
2016                 if (pch->ppp != 0)
2017                         unit = pch->ppp->file.index;
2018                 read_unlock_bh(&pch->upl);
2019         }
2020         return unit;
2021 }
2022
2023 /*
2024  * Disconnect a channel from the generic layer.
2025  * This must be called in process context.
2026  */
2027 void
2028 ppp_unregister_channel(struct ppp_channel *chan)
2029 {
2030         struct channel *pch = chan->ppp;
2031
2032         if (pch == 0)
2033                 return;         /* should never happen */
2034         chan->ppp = NULL;
2035
2036         /*
2037          * This ensures that we have returned from any calls into the
2038          * the channel's start_xmit or ioctl routine before we proceed.
2039          */
2040         down_write(&pch->chan_sem);
2041         spin_lock_bh(&pch->downl);
2042         pch->chan = NULL;
2043         spin_unlock_bh(&pch->downl);
2044         up_write(&pch->chan_sem);
2045         ppp_disconnect_channel(pch);
2046         spin_lock_bh(&all_channels_lock);
2047         list_del(&pch->list);
2048         spin_unlock_bh(&all_channels_lock);
2049         pch->file.dead = 1;
2050         wake_up_interruptible(&pch->file.rwait);
2051         if (atomic_dec_and_test(&pch->file.refcnt))
2052                 ppp_destroy_channel(pch);
2053 }
2054
2055 /*
2056  * Callback from a channel when it can accept more to transmit.
2057  * This should be called at BH/softirq level, not interrupt level.
2058  */
2059 void
2060 ppp_output_wakeup(struct ppp_channel *chan)
2061 {
2062         struct channel *pch = chan->ppp;
2063
2064         if (pch == 0)
2065                 return;
2066         ppp_channel_push(pch);
2067 }
2068
2069 /*
2070  * Compression control.
2071  */
2072
2073 /* Process the PPPIOCSCOMPRESS ioctl. */
2074 static int
2075 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2076 {
2077         int err;
2078         struct compressor *cp, *ocomp;
2079         struct ppp_option_data data;
2080         void *state, *ostate;
2081         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2082
2083         err = -EFAULT;
2084         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2085             || (data.length <= CCP_MAX_OPTION_LENGTH
2086                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2087                 goto out;
2088         err = -EINVAL;
2089         if (data.length > CCP_MAX_OPTION_LENGTH
2090             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2091                 goto out;
2092
2093         cp = find_compressor(ccp_option[0]);
2094 #ifdef CONFIG_KMOD
2095         if (cp == 0) {
2096                 request_module("ppp-compress-%d", ccp_option[0]);
2097                 cp = find_compressor(ccp_option[0]);
2098         }
2099 #endif /* CONFIG_KMOD */
2100         if (cp == 0)
2101                 goto out;
2102
2103         err = -ENOBUFS;
2104         if (data.transmit) {
2105                 state = cp->comp_alloc(ccp_option, data.length);
2106                 if (state != 0) {
2107                         ppp_xmit_lock(ppp);
2108                         ppp->xstate &= ~SC_COMP_RUN;
2109                         ocomp = ppp->xcomp;
2110                         ostate = ppp->xc_state;
2111                         ppp->xcomp = cp;
2112                         ppp->xc_state = state;
2113                         ppp_xmit_unlock(ppp);
2114                         if (ostate != 0) {
2115                                 ocomp->comp_free(ostate);
2116                                 module_put(ocomp->owner);
2117                         }
2118                         err = 0;
2119                 } else
2120                         module_put(cp->owner);
2121
2122         } else {
2123                 state = cp->decomp_alloc(ccp_option, data.length);
2124                 if (state != 0) {
2125                         ppp_recv_lock(ppp);
2126                         ppp->rstate &= ~SC_DECOMP_RUN;
2127                         ocomp = ppp->rcomp;
2128                         ostate = ppp->rc_state;
2129                         ppp->rcomp = cp;
2130                         ppp->rc_state = state;
2131                         ppp_recv_unlock(ppp);
2132                         if (ostate != 0) {
2133                                 ocomp->decomp_free(ostate);
2134                                 module_put(ocomp->owner);
2135                         }
2136                         err = 0;
2137                 } else
2138                         module_put(cp->owner);
2139         }
2140
2141  out:
2142         return err;
2143 }
2144
2145 /*
2146  * Look at a CCP packet and update our state accordingly.
2147  * We assume the caller has the xmit or recv path locked.
2148  */
2149 static void
2150 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2151 {
2152         unsigned char *dp;
2153         int len;
2154
2155         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2156                 return; /* no header */
2157         dp = skb->data + 2;
2158
2159         switch (CCP_CODE(dp)) {
2160         case CCP_CONFREQ:
2161
2162                 /* A ConfReq starts negotiation of compression
2163                  * in one direction of transmission,
2164                  * and hence brings it down...but which way?
2165                  *
2166                  * Remember:
2167                  * A ConfReq indicates what the sender would like to receive
2168                  */
2169                 if(inbound)
2170                         /* He is proposing what I should send */
2171                         ppp->xstate &= ~SC_COMP_RUN;
2172                 else
2173                         /* I am proposing to what he should send */
2174                         ppp->rstate &= ~SC_DECOMP_RUN;
2175
2176                 break;
2177
2178         case CCP_TERMREQ:
2179         case CCP_TERMACK:
2180                 /*
2181                  * CCP is going down, both directions of transmission
2182                  */
2183                 ppp->rstate &= ~SC_DECOMP_RUN;
2184                 ppp->xstate &= ~SC_COMP_RUN;
2185                 break;
2186
2187         case CCP_CONFACK:
2188                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2189                         break;
2190                 len = CCP_LENGTH(dp);
2191                 if (!pskb_may_pull(skb, len + 2))
2192                         return;         /* too short */
2193                 dp += CCP_HDRLEN;
2194                 len -= CCP_HDRLEN;
2195                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2196                         break;
2197                 if (inbound) {
2198                         /* we will start receiving compressed packets */
2199                         if (ppp->rc_state == 0)
2200                                 break;
2201                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2202                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2203                                 ppp->rstate |= SC_DECOMP_RUN;
2204                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2205                         }
2206                 } else {
2207                         /* we will soon start sending compressed packets */
2208                         if (ppp->xc_state == 0)
2209                                 break;
2210                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2211                                         ppp->file.index, 0, ppp->debug))
2212                                 ppp->xstate |= SC_COMP_RUN;
2213                 }
2214                 break;
2215
2216         case CCP_RESETACK:
2217                 /* reset the [de]compressor */
2218                 if ((ppp->flags & SC_CCP_UP) == 0)
2219                         break;
2220                 if (inbound) {
2221                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2222                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2223                                 ppp->rstate &= ~SC_DC_ERROR;
2224                         }
2225                 } else {
2226                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2227                                 ppp->xcomp->comp_reset(ppp->xc_state);
2228                 }
2229                 break;
2230         }
2231 }
2232
2233 /* Free up compression resources. */
2234 static void
2235 ppp_ccp_closed(struct ppp *ppp)
2236 {
2237         void *xstate, *rstate;
2238         struct compressor *xcomp, *rcomp;
2239
2240         ppp_lock(ppp);
2241         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2242         ppp->xstate = 0;
2243         xcomp = ppp->xcomp;
2244         xstate = ppp->xc_state;
2245         ppp->xc_state = NULL;
2246         ppp->rstate = 0;
2247         rcomp = ppp->rcomp;
2248         rstate = ppp->rc_state;
2249         ppp->rc_state = NULL;
2250         ppp_unlock(ppp);
2251
2252         if (xstate) {
2253                 xcomp->comp_free(xstate);
2254                 module_put(xcomp->owner);
2255         }
2256         if (rstate) {
2257                 rcomp->decomp_free(rstate);
2258                 module_put(rcomp->owner);
2259         }
2260 }
2261
2262 /* List of compressors. */
2263 static LIST_HEAD(compressor_list);
2264 static DEFINE_SPINLOCK(compressor_list_lock);
2265
2266 struct compressor_entry {
2267         struct list_head list;
2268         struct compressor *comp;
2269 };
2270
2271 static struct compressor_entry *
2272 find_comp_entry(int proto)
2273 {
2274         struct compressor_entry *ce;
2275         struct list_head *list = &compressor_list;
2276
2277         while ((list = list->next) != &compressor_list) {
2278                 ce = list_entry(list, struct compressor_entry, list);
2279                 if (ce->comp->compress_proto == proto)
2280                         return ce;
2281         }
2282         return NULL;
2283 }
2284
2285 /* Register a compressor */
2286 int
2287 ppp_register_compressor(struct compressor *cp)
2288 {
2289         struct compressor_entry *ce;
2290         int ret;
2291         spin_lock(&compressor_list_lock);
2292         ret = -EEXIST;
2293         if (find_comp_entry(cp->compress_proto) != 0)
2294                 goto out;
2295         ret = -ENOMEM;
2296         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2297         if (ce == 0)
2298                 goto out;
2299         ret = 0;
2300         ce->comp = cp;
2301         list_add(&ce->list, &compressor_list);
2302  out:
2303         spin_unlock(&compressor_list_lock);
2304         return ret;
2305 }
2306
2307 /* Unregister a compressor */
2308 void
2309 ppp_unregister_compressor(struct compressor *cp)
2310 {
2311         struct compressor_entry *ce;
2312
2313         spin_lock(&compressor_list_lock);
2314         ce = find_comp_entry(cp->compress_proto);
2315         if (ce != 0 && ce->comp == cp) {
2316                 list_del(&ce->list);
2317                 kfree(ce);
2318         }
2319         spin_unlock(&compressor_list_lock);
2320 }
2321
2322 /* Find a compressor. */
2323 static struct compressor *
2324 find_compressor(int type)
2325 {
2326         struct compressor_entry *ce;
2327         struct compressor *cp = NULL;
2328
2329         spin_lock(&compressor_list_lock);
2330         ce = find_comp_entry(type);
2331         if (ce != 0) {
2332                 cp = ce->comp;
2333                 if (!try_module_get(cp->owner))
2334                         cp = NULL;
2335         }
2336         spin_unlock(&compressor_list_lock);
2337         return cp;
2338 }
2339
2340 /*
2341  * Miscelleneous stuff.
2342  */
2343
2344 static void
2345 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2346 {
2347         struct slcompress *vj = ppp->vj;
2348
2349         memset(st, 0, sizeof(*st));
2350         st->p.ppp_ipackets = ppp->stats.rx_packets;
2351         st->p.ppp_ierrors = ppp->stats.rx_errors;
2352         st->p.ppp_ibytes = ppp->stats.rx_bytes;
2353         st->p.ppp_opackets = ppp->stats.tx_packets;
2354         st->p.ppp_oerrors = ppp->stats.tx_errors;
2355         st->p.ppp_obytes = ppp->stats.tx_bytes;
2356         if (vj == 0)
2357                 return;
2358         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2359         st->vj.vjs_compressed = vj->sls_o_compressed;
2360         st->vj.vjs_searches = vj->sls_o_searches;
2361         st->vj.vjs_misses = vj->sls_o_misses;
2362         st->vj.vjs_errorin = vj->sls_i_error;
2363         st->vj.vjs_tossed = vj->sls_i_tossed;
2364         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2365         st->vj.vjs_compressedin = vj->sls_i_compressed;
2366 }
2367
2368 /*
2369  * Stuff for handling the lists of ppp units and channels
2370  * and for initialization.
2371  */
2372
2373 /*
2374  * Create a new ppp interface unit.  Fails if it can't allocate memory
2375  * or if there is already a unit with the requested number.
2376  * unit == -1 means allocate a new number.
2377  */
2378 static struct ppp *
2379 ppp_create_interface(int unit, int *retp)
2380 {
2381         struct ppp *ppp;
2382         struct net_device *dev = NULL;
2383         int ret = -ENOMEM;
2384         int i;
2385
2386         ppp = kmalloc(sizeof(struct ppp), GFP_KERNEL);
2387         if (!ppp)
2388                 goto out;
2389         dev = alloc_netdev(0, "", ppp_setup);
2390         if (!dev)
2391                 goto out1;
2392         memset(ppp, 0, sizeof(struct ppp));
2393
2394         ppp->mru = PPP_MRU;
2395         init_ppp_file(&ppp->file, INTERFACE);
2396         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2397         for (i = 0; i < NUM_NP; ++i)
2398                 ppp->npmode[i] = NPMODE_PASS;
2399         INIT_LIST_HEAD(&ppp->channels);
2400         spin_lock_init(&ppp->rlock);
2401         spin_lock_init(&ppp->wlock);
2402 #ifdef CONFIG_PPP_MULTILINK
2403         ppp->minseq = -1;
2404         skb_queue_head_init(&ppp->mrq);
2405 #endif /* CONFIG_PPP_MULTILINK */
2406         ppp->dev = dev;
2407         dev->priv = ppp;
2408
2409         dev->hard_start_xmit = ppp_start_xmit;
2410         dev->get_stats = ppp_net_stats;
2411         dev->do_ioctl = ppp_net_ioctl;
2412
2413         ret = -EEXIST;
2414         down(&all_ppp_sem);
2415         if (unit < 0)
2416                 unit = cardmap_find_first_free(all_ppp_units);
2417         else if (cardmap_get(all_ppp_units, unit) != NULL)
2418                 goto out2;      /* unit already exists */
2419
2420         /* Initialize the new ppp unit */
2421         ppp->file.index = unit;
2422         sprintf(dev->name, "ppp%d", unit);
2423
2424         ret = register_netdev(dev);
2425         if (ret != 0) {
2426                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2427                        dev->name, ret);
2428                 goto out2;
2429         }
2430
2431         atomic_inc(&ppp_unit_count);
2432         cardmap_set(&all_ppp_units, unit, ppp);
2433         up(&all_ppp_sem);
2434         *retp = 0;
2435         return ppp;
2436
2437 out2:
2438         up(&all_ppp_sem);
2439         free_netdev(dev);
2440 out1:
2441         kfree(ppp);
2442 out:
2443         *retp = ret;
2444         return NULL;
2445 }
2446
2447 /*
2448  * Initialize a ppp_file structure.
2449  */
2450 static void
2451 init_ppp_file(struct ppp_file *pf, int kind)
2452 {
2453         pf->kind = kind;
2454         skb_queue_head_init(&pf->xq);
2455         skb_queue_head_init(&pf->rq);
2456         atomic_set(&pf->refcnt, 1);
2457         init_waitqueue_head(&pf->rwait);
2458 }
2459
2460 /*
2461  * Take down a ppp interface unit - called when the owning file
2462  * (the one that created the unit) is closed or detached.
2463  */
2464 static void ppp_shutdown_interface(struct ppp *ppp)
2465 {
2466         struct net_device *dev;
2467
2468         down(&all_ppp_sem);
2469         ppp_lock(ppp);
2470         dev = ppp->dev;
2471         ppp->dev = NULL;
2472         ppp_unlock(ppp);
2473         /* This will call dev_close() for us. */
2474         if (dev) {
2475                 unregister_netdev(dev);
2476                 free_netdev(dev);
2477         }
2478         cardmap_set(&all_ppp_units, ppp->file.index, NULL);
2479         ppp->file.dead = 1;
2480         ppp->owner = NULL;
2481         wake_up_interruptible(&ppp->file.rwait);
2482         up(&all_ppp_sem);
2483 }
2484
2485 /*
2486  * Free the memory used by a ppp unit.  This is only called once
2487  * there are no channels connected to the unit and no file structs
2488  * that reference the unit.
2489  */
2490 static void ppp_destroy_interface(struct ppp *ppp)
2491 {
2492         atomic_dec(&ppp_unit_count);
2493
2494         if (!ppp->file.dead || ppp->n_channels) {
2495                 /* "can't happen" */
2496                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2497                        "n_channels=%d !\n", ppp, ppp->file.dead,
2498                        ppp->n_channels);
2499                 return;
2500         }
2501
2502         ppp_ccp_closed(ppp);
2503         if (ppp->vj) {
2504                 slhc_free(ppp->vj);
2505                 ppp->vj = NULL;
2506         }
2507         skb_queue_purge(&ppp->file.xq);
2508         skb_queue_purge(&ppp->file.rq);
2509 #ifdef CONFIG_PPP_MULTILINK
2510         skb_queue_purge(&ppp->mrq);
2511 #endif /* CONFIG_PPP_MULTILINK */
2512 #ifdef CONFIG_PPP_FILTER
2513         kfree(ppp->pass_filter);
2514         ppp->pass_filter = NULL;
2515         kfree(ppp->active_filter);
2516         ppp->active_filter = NULL;
2517 #endif /* CONFIG_PPP_FILTER */
2518
2519         kfree(ppp);
2520 }
2521
2522 /*
2523  * Locate an existing ppp unit.
2524  * The caller should have locked the all_ppp_sem.
2525  */
2526 static struct ppp *
2527 ppp_find_unit(int unit)
2528 {
2529         return cardmap_get(all_ppp_units, unit);
2530 }
2531
2532 /*
2533  * Locate an existing ppp channel.
2534  * The caller should have locked the all_channels_lock.
2535  * First we look in the new_channels list, then in the
2536  * all_channels list.  If found in the new_channels list,
2537  * we move it to the all_channels list.  This is for speed
2538  * when we have a lot of channels in use.
2539  */
2540 static struct channel *
2541 ppp_find_channel(int unit)
2542 {
2543         struct channel *pch;
2544         struct list_head *list;
2545
2546         list = &new_channels;
2547         while ((list = list->next) != &new_channels) {
2548                 pch = list_entry(list, struct channel, list);
2549                 if (pch->file.index == unit) {
2550                         list_del(&pch->list);
2551                         list_add(&pch->list, &all_channels);
2552                         return pch;
2553                 }
2554         }
2555         list = &all_channels;
2556         while ((list = list->next) != &all_channels) {
2557                 pch = list_entry(list, struct channel, list);
2558                 if (pch->file.index == unit)
2559                         return pch;
2560         }
2561         return NULL;
2562 }
2563
2564 /*
2565  * Connect a PPP channel to a PPP interface unit.
2566  */
2567 static int
2568 ppp_connect_channel(struct channel *pch, int unit)
2569 {
2570         struct ppp *ppp;
2571         int ret = -ENXIO;
2572         int hdrlen;
2573
2574         down(&all_ppp_sem);
2575         ppp = ppp_find_unit(unit);
2576         if (ppp == 0)
2577                 goto out;
2578         write_lock_bh(&pch->upl);
2579         ret = -EINVAL;
2580         if (pch->ppp != 0)
2581                 goto outl;
2582
2583         ppp_lock(ppp);
2584         if (pch->file.hdrlen > ppp->file.hdrlen)
2585                 ppp->file.hdrlen = pch->file.hdrlen;
2586         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2587         if (ppp->dev && hdrlen > ppp->dev->hard_header_len)
2588                 ppp->dev->hard_header_len = hdrlen;
2589         list_add_tail(&pch->clist, &ppp->channels);
2590         ++ppp->n_channels;
2591         pch->ppp = ppp;
2592         atomic_inc(&ppp->file.refcnt);
2593         ppp_unlock(ppp);
2594         ret = 0;
2595
2596  outl:
2597         write_unlock_bh(&pch->upl);
2598  out:
2599         up(&all_ppp_sem);
2600         return ret;
2601 }
2602
2603 /*
2604  * Disconnect a channel from its ppp unit.
2605  */
2606 static int
2607 ppp_disconnect_channel(struct channel *pch)
2608 {
2609         struct ppp *ppp;
2610         int err = -EINVAL;
2611
2612         write_lock_bh(&pch->upl);
2613         ppp = pch->ppp;
2614         pch->ppp = NULL;
2615         write_unlock_bh(&pch->upl);
2616         if (ppp != 0) {
2617                 /* remove it from the ppp unit's list */
2618                 ppp_lock(ppp);
2619                 list_del(&pch->clist);
2620                 if (--ppp->n_channels == 0)
2621                         wake_up_interruptible(&ppp->file.rwait);
2622                 ppp_unlock(ppp);
2623                 if (atomic_dec_and_test(&ppp->file.refcnt))
2624                         ppp_destroy_interface(ppp);
2625                 err = 0;
2626         }
2627         return err;
2628 }
2629
2630 /*
2631  * Free up the resources used by a ppp channel.
2632  */
2633 static void ppp_destroy_channel(struct channel *pch)
2634 {
2635         atomic_dec(&channel_count);
2636
2637         if (!pch->file.dead) {
2638                 /* "can't happen" */
2639                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2640                        pch);
2641                 return;
2642         }
2643         skb_queue_purge(&pch->file.xq);
2644         skb_queue_purge(&pch->file.rq);
2645         kfree(pch);
2646 }
2647
2648 static void __exit ppp_cleanup(void)
2649 {
2650         /* should never happen */
2651         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2652                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2653         cardmap_destroy(&all_ppp_units);
2654         if (unregister_chrdev(PPP_MAJOR, "ppp") != 0)
2655                 printk(KERN_ERR "PPP: failed to unregister PPP device\n");
2656         devfs_remove("ppp");
2657         class_simple_device_remove(MKDEV(PPP_MAJOR, 0));
2658         class_simple_destroy(ppp_class);
2659 }
2660
2661 /*
2662  * Cardmap implementation.
2663  */
2664 static void *cardmap_get(struct cardmap *map, unsigned int nr)
2665 {
2666         struct cardmap *p;
2667         int i;
2668
2669         for (p = map; p != NULL; ) {
2670                 if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
2671                         return NULL;
2672                 if (p->shift == 0)
2673                         return p->ptr[i];
2674                 nr &= ~(CARDMAP_MASK << p->shift);
2675                 p = p->ptr[i];
2676         }
2677         return NULL;
2678 }
2679
2680 static void cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
2681 {
2682         struct cardmap *p;
2683         int i;
2684
2685         p = *pmap;
2686         if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
2687                 do {
2688                         /* need a new top level */
2689                         struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
2690                         memset(np, 0, sizeof(*np));
2691                         np->ptr[0] = p;
2692                         if (p != NULL) {
2693                                 np->shift = p->shift + CARDMAP_ORDER;
2694                                 p->parent = np;
2695                         } else
2696                                 np->shift = 0;
2697                         p = np;
2698                 } while ((nr >> p->shift) >= CARDMAP_WIDTH);
2699                 *pmap = p;
2700         }
2701         while (p->shift > 0) {
2702                 i = (nr >> p->shift) & CARDMAP_MASK;
2703                 if (p->ptr[i] == NULL) {
2704                         struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
2705                         memset(np, 0, sizeof(*np));
2706                         np->shift = p->shift - CARDMAP_ORDER;
2707                         np->parent = p;
2708                         p->ptr[i] = np;
2709                 }
2710                 if (ptr == NULL)
2711                         clear_bit(i, &p->inuse);
2712                 p = p->ptr[i];
2713         }
2714         i = nr & CARDMAP_MASK;
2715         p->ptr[i] = ptr;
2716         if (ptr != NULL)
2717                 set_bit(i, &p->inuse);
2718         else
2719                 clear_bit(i, &p->inuse);
2720 }
2721
2722 static unsigned int cardmap_find_first_free(struct cardmap *map)
2723 {
2724         struct cardmap *p;
2725         unsigned int nr = 0;
2726         int i;
2727
2728         if ((p = map) == NULL)
2729                 return 0;
2730         for (;;) {
2731                 i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
2732                 if (i >= CARDMAP_WIDTH) {
2733                         if (p->parent == NULL)
2734                                 return CARDMAP_WIDTH << p->shift;
2735                         p = p->parent;
2736                         i = (nr >> p->shift) & CARDMAP_MASK;
2737                         set_bit(i, &p->inuse);
2738                         continue;
2739                 }
2740                 nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
2741                 if (p->shift == 0 || p->ptr[i] == NULL)
2742                         return nr;
2743                 p = p->ptr[i];
2744         }
2745 }
2746
2747 static void cardmap_destroy(struct cardmap **pmap)
2748 {
2749         struct cardmap *p, *np;
2750         int i;
2751
2752         for (p = *pmap; p != NULL; p = np) {
2753                 if (p->shift != 0) {
2754                         for (i = 0; i < CARDMAP_WIDTH; ++i)
2755                                 if (p->ptr[i] != NULL)
2756                                         break;
2757                         if (i < CARDMAP_WIDTH) {
2758                                 np = p->ptr[i];
2759                                 p->ptr[i] = NULL;
2760                                 continue;
2761                         }
2762                 }
2763                 np = p->parent;
2764                 kfree(p);
2765         }
2766         *pmap = NULL;
2767 }
2768
2769 /* Module/initialization stuff */
2770
2771 module_init(ppp_init);
2772 module_exit(ppp_cleanup);
2773
2774 EXPORT_SYMBOL(ppp_register_channel);
2775 EXPORT_SYMBOL(ppp_unregister_channel);
2776 EXPORT_SYMBOL(ppp_channel_index);
2777 EXPORT_SYMBOL(ppp_unit_number);
2778 EXPORT_SYMBOL(ppp_input);
2779 EXPORT_SYMBOL(ppp_input_error);
2780 EXPORT_SYMBOL(ppp_output_wakeup);
2781 EXPORT_SYMBOL(ppp_register_compressor);
2782 EXPORT_SYMBOL(ppp_unregister_compressor);
2783 MODULE_LICENSE("GPL");
2784 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2785 MODULE_ALIAS("/dev/ppp");