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 *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_create(THIS_MODULE, "ppp");
 862                 if (IS_ERR(ppp_class)) {
 863                         err = PTR_ERR(ppp_class);
 864                         goto out_chrdev;
 865                 }
 866                 class_device_create(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_device_destroy(ppp_class, MKDEV(PPP_MAJOR,0));
 880         class_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_for_each_entry(pch, &ppp->channels, clist) {
1236                 navail += pch->avail = (pch->chan != NULL);
1237                 if (pch->avail) {
1238                         if (skb_queue_empty(&pch->file.xq) ||
1239                             !pch->had_frag) {
1240                                 pch->avail = 2;
1241                                 ++nfree;
1242                         }
1243                         if (!pch->had_frag && i < ppp->nxchan)
1244                                 ppp->nxchan = i;
1245                 }
1246                 ++i;
1247         }
1248
1249         /*
1250          * Don't start sending this packet unless at least half of
1251          * the channels are free.  This gives much better TCP
1252          * performance if we have a lot of channels.
1253          */
1254         if (nfree == 0 || nfree < navail / 2)
1255                 return 0;       /* can't take now, leave it in xmit_pending */
1256
1257         /* Do protocol field compression (XXX this should be optional) */
1258         p = skb->data;
1259         len = skb->len;
1260         if (*p == 0) {
1261                 ++p;
1262                 --len;
1263         }
1264
1265         /*
1266          * Decide on fragment size.
1267          * We create a fragment for each free channel regardless of
1268          * how small they are (i.e. even 0 length) in order to minimize
1269          * the time that it will take to detect when a channel drops
1270          * a fragment.
1271          */
1272         fragsize = len;
1273         if (nfree > 1)
1274                 fragsize = ROUNDUP(fragsize, nfree);
1275         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1276            except if nbigger==0, then they all get fragsize. */
1277         nbigger = len % nfree;
1278
1279         /* skip to the channel after the one we last used
1280            and start at that one */
1281         list = &ppp->channels;
1282         for (i = 0; i < ppp->nxchan; ++i) {
1283                 list = list->next;
1284                 if (list == &ppp->channels) {
1285                         i = 0;
1286                         break;
1287                 }
1288         }
1289
1290         /* create a fragment for each channel */
1291         bits = B;
1292         while (nfree > 0 || len > 0) {
1293                 list = list->next;
1294                 if (list == &ppp->channels) {
1295                         i = 0;
1296                         continue;
1297                 }
1298                 pch = list_entry(list, struct channel, clist);
1299                 ++i;
1300                 if (!pch->avail)
1301                         continue;
1302
1303                 /*
1304                  * Skip this channel if it has a fragment pending already and
1305                  * we haven't given a fragment to all of the free channels.
1306                  */
1307                 if (pch->avail == 1) {
1308                         if (nfree > 0)
1309                                 continue;
1310                 } else {
1311                         --nfree;
1312                         pch->avail = 1;
1313                 }
1314
1315                 /* check the channel's mtu and whether it is still attached. */
1316                 spin_lock_bh(&pch->downl);
1317                 if (pch->chan == NULL) {
1318                         /* can't use this channel, it's being deregistered */
1319                         spin_unlock_bh(&pch->downl);
1320                         pch->avail = 0;
1321                         if (--navail == 0)
1322                                 break;
1323                         continue;
1324                 }
1325
1326                 /*
1327                  * Create a fragment for this channel of
1328                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1329                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1330                  * MTU, so we use mtu = 2 + hdrlen.
1331                  */
1332                 if (fragsize > len)
1333                         fragsize = len;
1334                 flen = fragsize;
1335                 mtu = pch->chan->mtu + 2 - hdrlen;
1336                 if (mtu < 4)
1337                         mtu = 4;
1338                 if (flen > mtu)
1339                         flen = mtu;
1340                 if (flen == len && nfree == 0)
1341                         bits |= E;
1342                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1343                 if (frag == 0)
1344                         goto noskb;
1345                 q = skb_put(frag, flen + hdrlen);
1346
1347                 /* make the MP header */
1348                 q[0] = PPP_MP >> 8;
1349                 q[1] = PPP_MP;
1350                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1351                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1352                         q[3] = ppp->nxseq;
1353                 } else {
1354                         q[2] = bits;
1355                         q[3] = ppp->nxseq >> 16;
1356                         q[4] = ppp->nxseq >> 8;
1357                         q[5] = ppp->nxseq;
1358                 }
1359
1360                 /*
1361                  * Copy the data in.
1362                  * Unfortunately there is a bug in older versions of
1363                  * the Linux PPP multilink reconstruction code where it
1364                  * drops 0-length fragments.  Therefore we make sure the
1365                  * fragment has at least one byte of data.  Any bytes
1366                  * we add in this situation will end up as padding on the
1367                  * end of the reconstructed packet.
1368                  */
1369                 if (flen == 0)
1370                         *skb_put(frag, 1) = 0;
1371                 else
1372                         memcpy(q + hdrlen, p, flen);
1373
1374                 /* try to send it down the channel */
1375                 chan = pch->chan;
1376                 if (!skb_queue_empty(&pch->file.xq) ||
1377                     !chan->ops->start_xmit(chan, frag))
1378                         skb_queue_tail(&pch->file.xq, frag);
1379                 pch->had_frag = 1;
1380                 p += flen;
1381                 len -= flen;
1382                 ++ppp->nxseq;
1383                 bits = 0;
1384                 spin_unlock_bh(&pch->downl);
1385
1386                 if (--nbigger == 0 && fragsize > 0)
1387                         --fragsize;
1388         }
1389         ppp->nxchan = i;
1390
1391         return 1;
1392
1393  noskb:
1394         spin_unlock_bh(&pch->downl);
1395         if (ppp->debug & 1)
1396                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1397         ++ppp->stats.tx_errors;
1398         ++ppp->nxseq;
1399         return 1;       /* abandon the frame */
1400 }
1401 #endif /* CONFIG_PPP_MULTILINK */
1402
1403 /*
1404  * Try to send data out on a channel.
1405  */
1406 static void
1407 ppp_channel_push(struct channel *pch)
1408 {
1409         struct sk_buff *skb;
1410         struct ppp *ppp;
1411
1412         spin_lock_bh(&pch->downl);
1413         if (pch->chan != 0) {
1414                 while (!skb_queue_empty(&pch->file.xq)) {
1415                         skb = skb_dequeue(&pch->file.xq);
1416                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1417                                 /* put the packet back and try again later */
1418                                 skb_queue_head(&pch->file.xq, skb);
1419                                 break;
1420                         }
1421                 }
1422         } else {
1423                 /* channel got deregistered */
1424                 skb_queue_purge(&pch->file.xq);
1425         }
1426         spin_unlock_bh(&pch->downl);
1427         /* see if there is anything from the attached unit to be sent */
1428         if (skb_queue_empty(&pch->file.xq)) {
1429                 read_lock_bh(&pch->upl);
1430                 ppp = pch->ppp;
1431                 if (ppp != 0)
1432                         ppp_xmit_process(ppp);
1433                 read_unlock_bh(&pch->upl);
1434         }
1435 }
1436
1437 /*
1438  * Receive-side routines.
1439  */
1440
1441 /* misuse a few fields of the skb for MP reconstruction */
1442 #define sequence        priority
1443 #define BEbits          cb[0]
1444
1445 static inline void
1446 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1447 {
1448         ppp_recv_lock(ppp);
1449         /* ppp->dev == 0 means interface is closing down */
1450         if (ppp->dev != 0)
1451                 ppp_receive_frame(ppp, skb, pch);
1452         else
1453                 kfree_skb(skb);
1454         ppp_recv_unlock(ppp);
1455 }
1456
1457 void
1458 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1459 {
1460         struct channel *pch = chan->ppp;
1461         int proto;
1462
1463         if (pch == 0 || skb->len == 0) {
1464                 kfree_skb(skb);
1465                 return;
1466         }
1467
1468         proto = PPP_PROTO(skb);
1469         read_lock_bh(&pch->upl);
1470         if (pch->ppp == 0 || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1471                 /* put it on the channel queue */
1472                 skb_queue_tail(&pch->file.rq, skb);
1473                 /* drop old frames if queue too long */
1474                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1475                        && (skb = skb_dequeue(&pch->file.rq)) != 0)
1476                         kfree_skb(skb);
1477                 wake_up_interruptible(&pch->file.rwait);
1478         } else {
1479                 ppp_do_recv(pch->ppp, skb, pch);
1480         }
1481         read_unlock_bh(&pch->upl);
1482 }
1483
1484 /* Put a 0-length skb in the receive queue as an error indication */
1485 void
1486 ppp_input_error(struct ppp_channel *chan, int code)
1487 {
1488         struct channel *pch = chan->ppp;
1489         struct sk_buff *skb;
1490
1491         if (pch == 0)
1492                 return;
1493
1494         read_lock_bh(&pch->upl);
1495         if (pch->ppp != 0) {
1496                 skb = alloc_skb(0, GFP_ATOMIC);
1497                 if (skb != 0) {
1498                         skb->len = 0;           /* probably unnecessary */
1499                         skb->cb[0] = code;
1500                         ppp_do_recv(pch->ppp, skb, pch);
1501                 }
1502         }
1503         read_unlock_bh(&pch->upl);
1504 }
1505
1506 /*
1507  * We come in here to process a received frame.
1508  * The receive side of the ppp unit is locked.
1509  */
1510 static void
1511 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1512 {
1513         if (skb->len >= 2) {
1514 #ifdef CONFIG_PPP_MULTILINK
1515                 /* XXX do channel-level decompression here */
1516                 if (PPP_PROTO(skb) == PPP_MP)
1517                         ppp_receive_mp_frame(ppp, skb, pch);
1518                 else
1519 #endif /* CONFIG_PPP_MULTILINK */
1520                         ppp_receive_nonmp_frame(ppp, skb);
1521                 return;
1522         }
1523
1524         if (skb->len > 0)
1525                 /* note: a 0-length skb is used as an error indication */
1526                 ++ppp->stats.rx_length_errors;
1527
1528         kfree_skb(skb);
1529         ppp_receive_error(ppp);
1530 }
1531
1532 static void
1533 ppp_receive_error(struct ppp *ppp)
1534 {
1535         ++ppp->stats.rx_errors;
1536         if (ppp->vj != 0)
1537                 slhc_toss(ppp->vj);
1538 }
1539
1540 static void
1541 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1542 {
1543         struct sk_buff *ns;
1544         int proto, len, npi;
1545
1546         /*
1547          * Decompress the frame, if compressed.
1548          * Note that some decompressors need to see uncompressed frames
1549          * that come in as well as compressed frames.
1550          */
1551         if (ppp->rc_state != 0 && (ppp->rstate & SC_DECOMP_RUN)
1552             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1553                 skb = ppp_decompress_frame(ppp, skb);
1554
1555         proto = PPP_PROTO(skb);
1556         switch (proto) {
1557         case PPP_VJC_COMP:
1558                 /* decompress VJ compressed packets */
1559                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1560                         goto err;
1561
1562                 if (skb_tailroom(skb) < 124) {
1563                         /* copy to a new sk_buff with more tailroom */
1564                         ns = dev_alloc_skb(skb->len + 128);
1565                         if (ns == 0) {
1566                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1567                                 goto err;
1568                         }
1569                         skb_reserve(ns, 2);
1570                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1571                         kfree_skb(skb);
1572                         skb = ns;
1573                 }
1574                 else if (!pskb_may_pull(skb, skb->len))
1575                         goto err;
1576
1577                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1578                 if (len <= 0) {
1579                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1580                         goto err;
1581                 }
1582                 len += 2;
1583                 if (len > skb->len)
1584                         skb_put(skb, len - skb->len);
1585                 else if (len < skb->len)
1586                         skb_trim(skb, len);
1587                 proto = PPP_IP;
1588                 break;
1589
1590         case PPP_VJC_UNCOMP:
1591                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1592                         goto err;
1593
1594                 /* Until we fix the decompressor need to make sure
1595                  * data portion is linear.
1596                  */
1597                 if (!pskb_may_pull(skb, skb->len))
1598                         goto err;
1599
1600                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1601                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1602                         goto err;
1603                 }
1604                 proto = PPP_IP;
1605                 break;
1606
1607         case PPP_CCP:
1608                 ppp_ccp_peek(ppp, skb, 1);
1609                 break;
1610         }
1611
1612         ++ppp->stats.rx_packets;
1613         ppp->stats.rx_bytes += skb->len - 2;
1614
1615         npi = proto_to_npindex(proto);
1616         if (npi < 0) {
1617                 /* control or unknown frame - pass it to pppd */
1618                 skb_queue_tail(&ppp->file.rq, skb);
1619                 /* limit queue length by dropping old frames */
1620                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1621                        && (skb = skb_dequeue(&ppp->file.rq)) != 0)
1622                         kfree_skb(skb);
1623                 /* wake up any process polling or blocking on read */
1624                 wake_up_interruptible(&ppp->file.rwait);
1625
1626         } else {
1627                 /* network protocol frame - give it to the kernel */
1628
1629 #ifdef CONFIG_PPP_FILTER
1630                 /* check if the packet passes the pass and active filters */
1631                 /* the filter instructions are constructed assuming
1632                    a four-byte PPP header on each packet */
1633                 *skb_push(skb, 2) = 0;
1634                 if (ppp->pass_filter
1635                     && sk_run_filter(skb, ppp->pass_filter,
1636                                      ppp->pass_len) == 0) {
1637                         if (ppp->debug & 1)
1638                                 printk(KERN_DEBUG "PPP: inbound frame not passed\n");
1639                         kfree_skb(skb);
1640                         return;
1641                 }
1642                 if (!(ppp->active_filter
1643                       && sk_run_filter(skb, ppp->active_filter,
1644                                        ppp->active_len) == 0))
1645                         ppp->last_recv = jiffies;
1646                 skb_pull(skb, 2);
1647 #else
1648                 ppp->last_recv = jiffies;
1649 #endif /* CONFIG_PPP_FILTER */
1650
1651                 if ((ppp->dev->flags & IFF_UP) == 0
1652                     || ppp->npmode[npi] != NPMODE_PASS) {
1653                         kfree_skb(skb);
1654                 } else {
1655                         skb_pull(skb, 2);       /* chop off protocol */
1656                         skb->dev = ppp->dev;
1657                         skb->protocol = htons(npindex_to_ethertype[npi]);
1658                         skb->mac.raw = skb->data;
1659                         netif_rx(skb);
1660                         ppp->dev->last_rx = jiffies;
1661                 }
1662         }
1663         return;
1664
1665  err:
1666         kfree_skb(skb);
1667         ppp_receive_error(ppp);
1668 }
1669
1670 static struct sk_buff *
1671 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1672 {
1673         int proto = PPP_PROTO(skb);
1674         struct sk_buff *ns;
1675         int len;
1676
1677         /* Until we fix all the decompressor's need to make sure
1678          * data portion is linear.
1679          */
1680         if (!pskb_may_pull(skb, skb->len))
1681                 goto err;
1682
1683         if (proto == PPP_COMP) {
1684                 ns = dev_alloc_skb(ppp->mru + PPP_HDRLEN);
1685                 if (ns == 0) {
1686                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1687                         goto err;
1688                 }
1689                 /* the decompressor still expects the A/C bytes in the hdr */
1690                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1691                                 skb->len + 2, ns->data, ppp->mru + PPP_HDRLEN);
1692                 if (len < 0) {
1693                         /* Pass the compressed frame to pppd as an
1694                            error indication. */
1695                         if (len == DECOMP_FATALERROR)
1696                                 ppp->rstate |= SC_DC_FERROR;
1697                         kfree_skb(ns);
1698                         goto err;
1699                 }
1700
1701                 kfree_skb(skb);
1702                 skb = ns;
1703                 skb_put(skb, len);
1704                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1705
1706         } else {
1707                 /* Uncompressed frame - pass to decompressor so it
1708                    can update its dictionary if necessary. */
1709                 if (ppp->rcomp->incomp)
1710                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1711                                            skb->len + 2);
1712         }
1713
1714         return skb;
1715
1716  err:
1717         ppp->rstate |= SC_DC_ERROR;
1718         ppp_receive_error(ppp);
1719         return skb;
1720 }
1721
1722 #ifdef CONFIG_PPP_MULTILINK
1723 /*
1724  * Receive a multilink frame.
1725  * We put it on the reconstruction queue and then pull off
1726  * as many completed frames as we can.
1727  */
1728 static void
1729 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1730 {
1731         u32 mask, seq;
1732         struct channel *ch;
1733         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1734
1735         if (!pskb_may_pull(skb, mphdrlen) || ppp->mrru == 0)
1736                 goto err;               /* no good, throw it away */
1737
1738         /* Decode sequence number and begin/end bits */
1739         if (ppp->flags & SC_MP_SHORTSEQ) {
1740                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1741                 mask = 0xfff;
1742         } else {
1743                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1744                 mask = 0xffffff;
1745         }
1746         skb->BEbits = skb->data[2];
1747         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1748
1749         /*
1750          * Do protocol ID decompression on the first fragment of each packet.
1751          */
1752         if ((skb->BEbits & B) && (skb->data[0] & 1))
1753                 *skb_push(skb, 1) = 0;
1754
1755         /*
1756          * Expand sequence number to 32 bits, making it as close
1757          * as possible to ppp->minseq.
1758          */
1759         seq |= ppp->minseq & ~mask;
1760         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1761                 seq += mask + 1;
1762         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1763                 seq -= mask + 1;        /* should never happen */
1764         skb->sequence = seq;
1765         pch->lastseq = seq;
1766
1767         /*
1768          * If this packet comes before the next one we were expecting,
1769          * drop it.
1770          */
1771         if (seq_before(seq, ppp->nextseq)) {
1772                 kfree_skb(skb);
1773                 ++ppp->stats.rx_dropped;
1774                 ppp_receive_error(ppp);
1775                 return;
1776         }
1777
1778         /*
1779          * Reevaluate minseq, the minimum over all channels of the
1780          * last sequence number received on each channel.  Because of
1781          * the increasing sequence number rule, we know that any fragment
1782          * before `minseq' which hasn't arrived is never going to arrive.
1783          * The list of channels can't change because we have the receive
1784          * side of the ppp unit locked.
1785          */
1786         list_for_each_entry(ch, &ppp->channels, clist) {
1787                 if (seq_before(ch->lastseq, seq))
1788                         seq = ch->lastseq;
1789         }
1790         if (seq_before(ppp->minseq, seq))
1791                 ppp->minseq = seq;
1792
1793         /* Put the fragment on the reconstruction queue */
1794         ppp_mp_insert(ppp, skb);
1795
1796         /* If the queue is getting long, don't wait any longer for packets
1797            before the start of the queue. */
1798         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN
1799             && seq_before(ppp->minseq, ppp->mrq.next->sequence))
1800                 ppp->minseq = ppp->mrq.next->sequence;
1801
1802         /* Pull completed packets off the queue and receive them. */
1803         while ((skb = ppp_mp_reconstruct(ppp)) != 0)
1804                 ppp_receive_nonmp_frame(ppp, skb);
1805
1806         return;
1807
1808  err:
1809         kfree_skb(skb);
1810         ppp_receive_error(ppp);
1811 }
1812
1813 /*
1814  * Insert a fragment on the MP reconstruction queue.
1815  * The queue is ordered by increasing sequence number.
1816  */
1817 static void
1818 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1819 {
1820         struct sk_buff *p;
1821         struct sk_buff_head *list = &ppp->mrq;
1822         u32 seq = skb->sequence;
1823
1824         /* N.B. we don't need to lock the list lock because we have the
1825            ppp unit receive-side lock. */
1826         for (p = list->next; p != (struct sk_buff *)list; p = p->next)
1827                 if (seq_before(seq, p->sequence))
1828                         break;
1829         __skb_insert(skb, p->prev, p, list);
1830 }
1831
1832 /*
1833  * Reconstruct a packet from the MP fragment queue.
1834  * We go through increasing sequence numbers until we find a
1835  * complete packet, or we get to the sequence number for a fragment
1836  * which hasn't arrived but might still do so.
1837  */
1838 struct sk_buff *
1839 ppp_mp_reconstruct(struct ppp *ppp)
1840 {
1841         u32 seq = ppp->nextseq;
1842         u32 minseq = ppp->minseq;
1843         struct sk_buff_head *list = &ppp->mrq;
1844         struct sk_buff *p, *next;
1845         struct sk_buff *head, *tail;
1846         struct sk_buff *skb = NULL;
1847         int lost = 0, len = 0;
1848
1849         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1850                 return NULL;
1851         head = list->next;
1852         tail = NULL;
1853         for (p = head; p != (struct sk_buff *) list; p = next) {
1854                 next = p->next;
1855                 if (seq_before(p->sequence, seq)) {
1856                         /* this can't happen, anyway ignore the skb */
1857                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1858                                p->sequence, seq);
1859                         head = next;
1860                         continue;
1861                 }
1862                 if (p->sequence != seq) {
1863                         /* Fragment `seq' is missing.  If it is after
1864                            minseq, it might arrive later, so stop here. */
1865                         if (seq_after(seq, minseq))
1866                                 break;
1867                         /* Fragment `seq' is lost, keep going. */
1868                         lost = 1;
1869                         seq = seq_before(minseq, p->sequence)?
1870                                 minseq + 1: p->sequence;
1871                         next = p;
1872                         continue;
1873                 }
1874
1875                 /*
1876                  * At this point we know that all the fragments from
1877                  * ppp->nextseq to seq are either present or lost.
1878                  * Also, there are no complete packets in the queue
1879                  * that have no missing fragments and end before this
1880                  * fragment.
1881                  */
1882
1883                 /* B bit set indicates this fragment starts a packet */
1884                 if (p->BEbits & B) {
1885                         head = p;
1886                         lost = 0;
1887                         len = 0;
1888                 }
1889
1890                 len += p->len;
1891
1892                 /* Got a complete packet yet? */
1893                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1894                         if (len > ppp->mrru + 2) {
1895                                 ++ppp->stats.rx_length_errors;
1896                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1897                                        " is too long (%d)\n", len);
1898                         } else if (p == head) {
1899                                 /* fragment is complete packet - reuse skb */
1900                                 tail = p;
1901                                 skb = skb_get(p);
1902                                 break;
1903                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1904                                 ++ppp->stats.rx_missed_errors;
1905                                 printk(KERN_DEBUG "PPP: no memory for "
1906                                        "reconstructed packet");
1907                         } else {
1908                                 tail = p;
1909                                 break;
1910                         }
1911                         ppp->nextseq = seq + 1;
1912                 }
1913
1914                 /*
1915                  * If this is the ending fragment of a packet,
1916                  * and we haven't found a complete valid packet yet,
1917                  * we can discard up to and including this fragment.
1918                  */
1919                 if (p->BEbits & E)
1920                         head = next;
1921
1922                 ++seq;
1923         }
1924
1925         /* If we have a complete packet, copy it all into one skb. */
1926         if (tail != NULL) {
1927                 /* If we have discarded any fragments,
1928                    signal a receive error. */
1929                 if (head->sequence != ppp->nextseq) {
1930                         if (ppp->debug & 1)
1931                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1932                                        ppp->nextseq, head->sequence-1);
1933                         ++ppp->stats.rx_dropped;
1934                         ppp_receive_error(ppp);
1935                 }
1936
1937                 if (head != tail)
1938                         /* copy to a single skb */
1939                         for (p = head; p != tail->next; p = p->next)
1940                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1941                 ppp->nextseq = tail->sequence + 1;
1942                 head = tail->next;
1943         }
1944
1945         /* Discard all the skbuffs that we have copied the data out of
1946            or that we can't use. */
1947         while ((p = list->next) != head) {
1948                 __skb_unlink(p, list);
1949                 kfree_skb(p);
1950         }
1951
1952         return skb;
1953 }
1954 #endif /* CONFIG_PPP_MULTILINK */
1955
1956 /*
1957  * Channel interface.
1958  */
1959
1960 /*
1961  * Create a new, unattached ppp channel.
1962  */
1963 int
1964 ppp_register_channel(struct ppp_channel *chan)
1965 {
1966         struct channel *pch;
1967
1968         pch = kmalloc(sizeof(struct channel), GFP_KERNEL);
1969         if (pch == 0)
1970                 return -ENOMEM;
1971         memset(pch, 0, sizeof(struct channel));
1972         pch->ppp = NULL;
1973         pch->chan = chan;
1974         chan->ppp = pch;
1975         init_ppp_file(&pch->file, CHANNEL);
1976         pch->file.hdrlen = chan->hdrlen;
1977 #ifdef CONFIG_PPP_MULTILINK
1978         pch->lastseq = -1;
1979 #endif /* CONFIG_PPP_MULTILINK */
1980         init_rwsem(&pch->chan_sem);
1981         spin_lock_init(&pch->downl);
1982         rwlock_init(&pch->upl);
1983         spin_lock_bh(&all_channels_lock);
1984         pch->file.index = ++last_channel_index;
1985         list_add(&pch->list, &new_channels);
1986         atomic_inc(&channel_count);
1987         spin_unlock_bh(&all_channels_lock);
1988         return 0;
1989 }
1990
1991 /*
1992  * Return the index of a channel.
1993  */
1994 int ppp_channel_index(struct ppp_channel *chan)
1995 {
1996         struct channel *pch = chan->ppp;
1997
1998         if (pch != 0)
1999                 return pch->file.index;
2000         return -1;
2001 }
2002
2003 /*
2004  * Return the PPP unit number to which a channel is connected.
2005  */
2006 int ppp_unit_number(struct ppp_channel *chan)
2007 {
2008         struct channel *pch = chan->ppp;
2009         int unit = -1;
2010
2011         if (pch != 0) {
2012                 read_lock_bh(&pch->upl);
2013                 if (pch->ppp != 0)
2014                         unit = pch->ppp->file.index;
2015                 read_unlock_bh(&pch->upl);
2016         }
2017         return unit;
2018 }
2019
2020 /*
2021  * Disconnect a channel from the generic layer.
2022  * This must be called in process context.
2023  */
2024 void
2025 ppp_unregister_channel(struct ppp_channel *chan)
2026 {
2027         struct channel *pch = chan->ppp;
2028
2029         if (pch == 0)
2030                 return;         /* should never happen */
2031         chan->ppp = NULL;
2032
2033         /*
2034          * This ensures that we have returned from any calls into the
2035          * the channel's start_xmit or ioctl routine before we proceed.
2036          */
2037         down_write(&pch->chan_sem);
2038         spin_lock_bh(&pch->downl);
2039         pch->chan = NULL;
2040         spin_unlock_bh(&pch->downl);
2041         up_write(&pch->chan_sem);
2042         ppp_disconnect_channel(pch);
2043         spin_lock_bh(&all_channels_lock);
2044         list_del(&pch->list);
2045         spin_unlock_bh(&all_channels_lock);
2046         pch->file.dead = 1;
2047         wake_up_interruptible(&pch->file.rwait);
2048         if (atomic_dec_and_test(&pch->file.refcnt))
2049                 ppp_destroy_channel(pch);
2050 }
2051
2052 /*
2053  * Callback from a channel when it can accept more to transmit.
2054  * This should be called at BH/softirq level, not interrupt level.
2055  */
2056 void
2057 ppp_output_wakeup(struct ppp_channel *chan)
2058 {
2059         struct channel *pch = chan->ppp;
2060
2061         if (pch == 0)
2062                 return;
2063         ppp_channel_push(pch);
2064 }
2065
2066 /*
2067  * Compression control.
2068  */
2069
2070 /* Process the PPPIOCSCOMPRESS ioctl. */
2071 static int
2072 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2073 {
2074         int err;
2075         struct compressor *cp, *ocomp;
2076         struct ppp_option_data data;
2077         void *state, *ostate;
2078         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2079
2080         err = -EFAULT;
2081         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2082             || (data.length <= CCP_MAX_OPTION_LENGTH
2083                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2084                 goto out;
2085         err = -EINVAL;
2086         if (data.length > CCP_MAX_OPTION_LENGTH
2087             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2088                 goto out;
2089
2090         cp = find_compressor(ccp_option[0]);
2091 #ifdef CONFIG_KMOD
2092         if (cp == 0) {
2093                 request_module("ppp-compress-%d", ccp_option[0]);
2094                 cp = find_compressor(ccp_option[0]);
2095         }
2096 #endif /* CONFIG_KMOD */
2097         if (cp == 0)
2098                 goto out;
2099
2100         err = -ENOBUFS;
2101         if (data.transmit) {
2102                 state = cp->comp_alloc(ccp_option, data.length);
2103                 if (state != 0) {
2104                         ppp_xmit_lock(ppp);
2105                         ppp->xstate &= ~SC_COMP_RUN;
2106                         ocomp = ppp->xcomp;
2107                         ostate = ppp->xc_state;
2108                         ppp->xcomp = cp;
2109                         ppp->xc_state = state;
2110                         ppp_xmit_unlock(ppp);
2111                         if (ostate != 0) {
2112                                 ocomp->comp_free(ostate);
2113                                 module_put(ocomp->owner);
2114                         }
2115                         err = 0;
2116                 } else
2117                         module_put(cp->owner);
2118
2119         } else {
2120                 state = cp->decomp_alloc(ccp_option, data.length);
2121                 if (state != 0) {
2122                         ppp_recv_lock(ppp);
2123                         ppp->rstate &= ~SC_DECOMP_RUN;
2124                         ocomp = ppp->rcomp;
2125                         ostate = ppp->rc_state;
2126                         ppp->rcomp = cp;
2127                         ppp->rc_state = state;
2128                         ppp_recv_unlock(ppp);
2129                         if (ostate != 0) {
2130                                 ocomp->decomp_free(ostate);
2131                                 module_put(ocomp->owner);
2132                         }
2133                         err = 0;
2134                 } else
2135                         module_put(cp->owner);
2136         }
2137
2138  out:
2139         return err;
2140 }
2141
2142 /*
2143  * Look at a CCP packet and update our state accordingly.
2144  * We assume the caller has the xmit or recv path locked.
2145  */
2146 static void
2147 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2148 {
2149         unsigned char *dp;
2150         int len;
2151
2152         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2153                 return; /* no header */
2154         dp = skb->data + 2;
2155
2156         switch (CCP_CODE(dp)) {
2157         case CCP_CONFREQ:
2158
2159                 /* A ConfReq starts negotiation of compression
2160                  * in one direction of transmission,
2161                  * and hence brings it down...but which way?
2162                  *
2163                  * Remember:
2164                  * A ConfReq indicates what the sender would like to receive
2165                  */
2166                 if(inbound)
2167                         /* He is proposing what I should send */
2168                         ppp->xstate &= ~SC_COMP_RUN;
2169                 else
2170                         /* I am proposing to what he should send */
2171                         ppp->rstate &= ~SC_DECOMP_RUN;
2172
2173                 break;
2174
2175         case CCP_TERMREQ:
2176         case CCP_TERMACK:
2177                 /*
2178                  * CCP is going down, both directions of transmission
2179                  */
2180                 ppp->rstate &= ~SC_DECOMP_RUN;
2181                 ppp->xstate &= ~SC_COMP_RUN;
2182                 break;
2183
2184         case CCP_CONFACK:
2185                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2186                         break;
2187                 len = CCP_LENGTH(dp);
2188                 if (!pskb_may_pull(skb, len + 2))
2189                         return;         /* too short */
2190                 dp += CCP_HDRLEN;
2191                 len -= CCP_HDRLEN;
2192                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2193                         break;
2194                 if (inbound) {
2195                         /* we will start receiving compressed packets */
2196                         if (ppp->rc_state == 0)
2197                                 break;
2198                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2199                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2200                                 ppp->rstate |= SC_DECOMP_RUN;
2201                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2202                         }
2203                 } else {
2204                         /* we will soon start sending compressed packets */
2205                         if (ppp->xc_state == 0)
2206                                 break;
2207                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2208                                         ppp->file.index, 0, ppp->debug))
2209                                 ppp->xstate |= SC_COMP_RUN;
2210                 }
2211                 break;
2212
2213         case CCP_RESETACK:
2214                 /* reset the [de]compressor */
2215                 if ((ppp->flags & SC_CCP_UP) == 0)
2216                         break;
2217                 if (inbound) {
2218                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2219                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2220                                 ppp->rstate &= ~SC_DC_ERROR;
2221                         }
2222                 } else {
2223                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2224                                 ppp->xcomp->comp_reset(ppp->xc_state);
2225                 }
2226                 break;
2227         }
2228 }
2229
2230 /* Free up compression resources. */
2231 static void
2232 ppp_ccp_closed(struct ppp *ppp)
2233 {
2234         void *xstate, *rstate;
2235         struct compressor *xcomp, *rcomp;
2236
2237         ppp_lock(ppp);
2238         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2239         ppp->xstate = 0;
2240         xcomp = ppp->xcomp;
2241         xstate = ppp->xc_state;
2242         ppp->xc_state = NULL;
2243         ppp->rstate = 0;
2244         rcomp = ppp->rcomp;
2245         rstate = ppp->rc_state;
2246         ppp->rc_state = NULL;
2247         ppp_unlock(ppp);
2248
2249         if (xstate) {
2250                 xcomp->comp_free(xstate);
2251                 module_put(xcomp->owner);
2252         }
2253         if (rstate) {
2254                 rcomp->decomp_free(rstate);
2255                 module_put(rcomp->owner);
2256         }
2257 }
2258
2259 /* List of compressors. */
2260 static LIST_HEAD(compressor_list);
2261 static DEFINE_SPINLOCK(compressor_list_lock);
2262
2263 struct compressor_entry {
2264         struct list_head list;
2265         struct compressor *comp;
2266 };
2267
2268 static struct compressor_entry *
2269 find_comp_entry(int proto)
2270 {
2271         struct compressor_entry *ce;
2272
2273         list_for_each_entry(ce, &compressor_list, list) {
2274                 if (ce->comp->compress_proto == proto)
2275                         return ce;
2276         }
2277         return NULL;
2278 }
2279
2280 /* Register a compressor */
2281 int
2282 ppp_register_compressor(struct compressor *cp)
2283 {
2284         struct compressor_entry *ce;
2285         int ret;
2286         spin_lock(&compressor_list_lock);
2287         ret = -EEXIST;
2288         if (find_comp_entry(cp->compress_proto) != 0)
2289                 goto out;
2290         ret = -ENOMEM;
2291         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2292         if (ce == 0)
2293                 goto out;
2294         ret = 0;
2295         ce->comp = cp;
2296         list_add(&ce->list, &compressor_list);
2297  out:
2298         spin_unlock(&compressor_list_lock);
2299         return ret;
2300 }
2301
2302 /* Unregister a compressor */
2303 void
2304 ppp_unregister_compressor(struct compressor *cp)
2305 {
2306         struct compressor_entry *ce;
2307
2308         spin_lock(&compressor_list_lock);
2309         ce = find_comp_entry(cp->compress_proto);
2310         if (ce != 0 && ce->comp == cp) {
2311                 list_del(&ce->list);
2312                 kfree(ce);
2313         }
2314         spin_unlock(&compressor_list_lock);
2315 }
2316
2317 /* Find a compressor. */
2318 static struct compressor *
2319 find_compressor(int type)
2320 {
2321         struct compressor_entry *ce;
2322         struct compressor *cp = NULL;
2323
2324         spin_lock(&compressor_list_lock);
2325         ce = find_comp_entry(type);
2326         if (ce != 0) {
2327                 cp = ce->comp;
2328                 if (!try_module_get(cp->owner))
2329                         cp = NULL;
2330         }
2331         spin_unlock(&compressor_list_lock);
2332         return cp;
2333 }
2334
2335 /*
2336  * Miscelleneous stuff.
2337  */
2338
2339 static void
2340 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2341 {
2342         struct slcompress *vj = ppp->vj;
2343
2344         memset(st, 0, sizeof(*st));
2345         st->p.ppp_ipackets = ppp->stats.rx_packets;
2346         st->p.ppp_ierrors = ppp->stats.rx_errors;
2347         st->p.ppp_ibytes = ppp->stats.rx_bytes;
2348         st->p.ppp_opackets = ppp->stats.tx_packets;
2349         st->p.ppp_oerrors = ppp->stats.tx_errors;
2350         st->p.ppp_obytes = ppp->stats.tx_bytes;
2351         if (vj == 0)
2352                 return;
2353         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2354         st->vj.vjs_compressed = vj->sls_o_compressed;
2355         st->vj.vjs_searches = vj->sls_o_searches;
2356         st->vj.vjs_misses = vj->sls_o_misses;
2357         st->vj.vjs_errorin = vj->sls_i_error;
2358         st->vj.vjs_tossed = vj->sls_i_tossed;
2359         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2360         st->vj.vjs_compressedin = vj->sls_i_compressed;
2361 }
2362
2363 /*
2364  * Stuff for handling the lists of ppp units and channels
2365  * and for initialization.
2366  */
2367
2368 /*
2369  * Create a new ppp interface unit.  Fails if it can't allocate memory
2370  * or if there is already a unit with the requested number.
2371  * unit == -1 means allocate a new number.
2372  */
2373 static struct ppp *
2374 ppp_create_interface(int unit, int *retp)
2375 {
2376         struct ppp *ppp;
2377         struct net_device *dev = NULL;
2378         int ret = -ENOMEM;
2379         int i;
2380
2381         ppp = kmalloc(sizeof(struct ppp), GFP_KERNEL);
2382         if (!ppp)
2383                 goto out;
2384         dev = alloc_netdev(0, "", ppp_setup);
2385         if (!dev)
2386                 goto out1;
2387         memset(ppp, 0, sizeof(struct ppp));
2388
2389         ppp->mru = PPP_MRU;
2390         init_ppp_file(&ppp->file, INTERFACE);
2391         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2392         for (i = 0; i < NUM_NP; ++i)
2393                 ppp->npmode[i] = NPMODE_PASS;
2394         INIT_LIST_HEAD(&ppp->channels);
2395         spin_lock_init(&ppp->rlock);
2396         spin_lock_init(&ppp->wlock);
2397 #ifdef CONFIG_PPP_MULTILINK
2398         ppp->minseq = -1;
2399         skb_queue_head_init(&ppp->mrq);
2400 #endif /* CONFIG_PPP_MULTILINK */
2401         ppp->dev = dev;
2402         dev->priv = ppp;
2403
2404         dev->hard_start_xmit = ppp_start_xmit;
2405         dev->get_stats = ppp_net_stats;
2406         dev->do_ioctl = ppp_net_ioctl;
2407
2408         ret = -EEXIST;
2409         down(&all_ppp_sem);
2410         if (unit < 0)
2411                 unit = cardmap_find_first_free(all_ppp_units);
2412         else if (cardmap_get(all_ppp_units, unit) != NULL)
2413                 goto out2;      /* unit already exists */
2414
2415         /* Initialize the new ppp unit */
2416         ppp->file.index = unit;
2417         sprintf(dev->name, "ppp%d", unit);
2418
2419         ret = register_netdev(dev);
2420         if (ret != 0) {
2421                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2422                        dev->name, ret);
2423                 goto out2;
2424         }
2425
2426         atomic_inc(&ppp_unit_count);
2427         cardmap_set(&all_ppp_units, unit, ppp);
2428         up(&all_ppp_sem);
2429         *retp = 0;
2430         return ppp;
2431
2432 out2:
2433         up(&all_ppp_sem);
2434         free_netdev(dev);
2435 out1:
2436         kfree(ppp);
2437 out:
2438         *retp = ret;
2439         return NULL;
2440 }
2441
2442 /*
2443  * Initialize a ppp_file structure.
2444  */
2445 static void
2446 init_ppp_file(struct ppp_file *pf, int kind)
2447 {
2448         pf->kind = kind;
2449         skb_queue_head_init(&pf->xq);
2450         skb_queue_head_init(&pf->rq);
2451         atomic_set(&pf->refcnt, 1);
2452         init_waitqueue_head(&pf->rwait);
2453 }
2454
2455 /*
2456  * Take down a ppp interface unit - called when the owning file
2457  * (the one that created the unit) is closed or detached.
2458  */
2459 static void ppp_shutdown_interface(struct ppp *ppp)
2460 {
2461         struct net_device *dev;
2462
2463         down(&all_ppp_sem);
2464         ppp_lock(ppp);
2465         dev = ppp->dev;
2466         ppp->dev = NULL;
2467         ppp_unlock(ppp);
2468         /* This will call dev_close() for us. */
2469         if (dev) {
2470                 unregister_netdev(dev);
2471                 free_netdev(dev);
2472         }
2473         cardmap_set(&all_ppp_units, ppp->file.index, NULL);
2474         ppp->file.dead = 1;
2475         ppp->owner = NULL;
2476         wake_up_interruptible(&ppp->file.rwait);
2477         up(&all_ppp_sem);
2478 }
2479
2480 /*
2481  * Free the memory used by a ppp unit.  This is only called once
2482  * there are no channels connected to the unit and no file structs
2483  * that reference the unit.
2484  */
2485 static void ppp_destroy_interface(struct ppp *ppp)
2486 {
2487         atomic_dec(&ppp_unit_count);
2488
2489         if (!ppp->file.dead || ppp->n_channels) {
2490                 /* "can't happen" */
2491                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2492                        "n_channels=%d !\n", ppp, ppp->file.dead,
2493                        ppp->n_channels);
2494                 return;
2495         }
2496
2497         ppp_ccp_closed(ppp);
2498         if (ppp->vj) {
2499                 slhc_free(ppp->vj);
2500                 ppp->vj = NULL;
2501         }
2502         skb_queue_purge(&ppp->file.xq);
2503         skb_queue_purge(&ppp->file.rq);
2504 #ifdef CONFIG_PPP_MULTILINK
2505         skb_queue_purge(&ppp->mrq);
2506 #endif /* CONFIG_PPP_MULTILINK */
2507 #ifdef CONFIG_PPP_FILTER
2508         kfree(ppp->pass_filter);
2509         ppp->pass_filter = NULL;
2510         kfree(ppp->active_filter);
2511         ppp->active_filter = NULL;
2512 #endif /* CONFIG_PPP_FILTER */
2513
2514         kfree(ppp);
2515 }
2516
2517 /*
2518  * Locate an existing ppp unit.
2519  * The caller should have locked the all_ppp_sem.
2520  */
2521 static struct ppp *
2522 ppp_find_unit(int unit)
2523 {
2524         return cardmap_get(all_ppp_units, unit);
2525 }
2526
2527 /*
2528  * Locate an existing ppp channel.
2529  * The caller should have locked the all_channels_lock.
2530  * First we look in the new_channels list, then in the
2531  * all_channels list.  If found in the new_channels list,
2532  * we move it to the all_channels list.  This is for speed
2533  * when we have a lot of channels in use.
2534  */
2535 static struct channel *
2536 ppp_find_channel(int unit)
2537 {
2538         struct channel *pch;
2539
2540         list_for_each_entry(pch, &new_channels, list) {
2541                 if (pch->file.index == unit) {
2542                         list_del(&pch->list);
2543                         list_add(&pch->list, &all_channels);
2544                         return pch;
2545                 }
2546         }
2547         list_for_each_entry(pch, &all_channels, list) {
2548                 if (pch->file.index == unit)
2549                         return pch;
2550         }
2551         return NULL;
2552 }
2553
2554 /*
2555  * Connect a PPP channel to a PPP interface unit.
2556  */
2557 static int
2558 ppp_connect_channel(struct channel *pch, int unit)
2559 {
2560         struct ppp *ppp;
2561         int ret = -ENXIO;
2562         int hdrlen;
2563
2564         down(&all_ppp_sem);
2565         ppp = ppp_find_unit(unit);
2566         if (ppp == 0)
2567                 goto out;
2568         write_lock_bh(&pch->upl);
2569         ret = -EINVAL;
2570         if (pch->ppp != 0)
2571                 goto outl;
2572
2573         ppp_lock(ppp);
2574         if (pch->file.hdrlen > ppp->file.hdrlen)
2575                 ppp->file.hdrlen = pch->file.hdrlen;
2576         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2577         if (ppp->dev && hdrlen > ppp->dev->hard_header_len)
2578                 ppp->dev->hard_header_len = hdrlen;
2579         list_add_tail(&pch->clist, &ppp->channels);
2580         ++ppp->n_channels;
2581         pch->ppp = ppp;
2582         atomic_inc(&ppp->file.refcnt);
2583         ppp_unlock(ppp);
2584         ret = 0;
2585
2586  outl:
2587         write_unlock_bh(&pch->upl);
2588  out:
2589         up(&all_ppp_sem);
2590         return ret;
2591 }
2592
2593 /*
2594  * Disconnect a channel from its ppp unit.
2595  */
2596 static int
2597 ppp_disconnect_channel(struct channel *pch)
2598 {
2599         struct ppp *ppp;
2600         int err = -EINVAL;
2601
2602         write_lock_bh(&pch->upl);
2603         ppp = pch->ppp;
2604         pch->ppp = NULL;
2605         write_unlock_bh(&pch->upl);
2606         if (ppp != 0) {
2607                 /* remove it from the ppp unit's list */
2608                 ppp_lock(ppp);
2609                 list_del(&pch->clist);
2610                 if (--ppp->n_channels == 0)
2611                         wake_up_interruptible(&ppp->file.rwait);
2612                 ppp_unlock(ppp);
2613                 if (atomic_dec_and_test(&ppp->file.refcnt))
2614                         ppp_destroy_interface(ppp);
2615                 err = 0;
2616         }
2617         return err;
2618 }
2619
2620 /*
2621  * Free up the resources used by a ppp channel.
2622  */
2623 static void ppp_destroy_channel(struct channel *pch)
2624 {
2625         atomic_dec(&channel_count);
2626
2627         if (!pch->file.dead) {
2628                 /* "can't happen" */
2629                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2630                        pch);
2631                 return;
2632         }
2633         skb_queue_purge(&pch->file.xq);
2634         skb_queue_purge(&pch->file.rq);
2635         kfree(pch);
2636 }
2637
2638 static void __exit ppp_cleanup(void)
2639 {
2640         /* should never happen */
2641         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2642                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2643         cardmap_destroy(&all_ppp_units);
2644         if (unregister_chrdev(PPP_MAJOR, "ppp") != 0)
2645                 printk(KERN_ERR "PPP: failed to unregister PPP device\n");
2646         devfs_remove("ppp");
2647         class_device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2648         class_destroy(ppp_class);
2649 }
2650
2651 /*
2652  * Cardmap implementation.
2653  */
2654 static void *cardmap_get(struct cardmap *map, unsigned int nr)
2655 {
2656         struct cardmap *p;
2657         int i;
2658
2659         for (p = map; p != NULL; ) {
2660                 if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
2661                         return NULL;
2662                 if (p->shift == 0)
2663                         return p->ptr[i];
2664                 nr &= ~(CARDMAP_MASK << p->shift);
2665                 p = p->ptr[i];
2666         }
2667         return NULL;
2668 }
2669
2670 static void cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
2671 {
2672         struct cardmap *p;
2673         int i;
2674
2675         p = *pmap;
2676         if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
2677                 do {
2678                         /* need a new top level */
2679                         struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
2680                         memset(np, 0, sizeof(*np));
2681                         np->ptr[0] = p;
2682                         if (p != NULL) {
2683                                 np->shift = p->shift + CARDMAP_ORDER;
2684                                 p->parent = np;
2685                         } else
2686                                 np->shift = 0;
2687                         p = np;
2688                 } while ((nr >> p->shift) >= CARDMAP_WIDTH);
2689                 *pmap = p;
2690         }
2691         while (p->shift > 0) {
2692                 i = (nr >> p->shift) & CARDMAP_MASK;
2693                 if (p->ptr[i] == NULL) {
2694                         struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
2695                         memset(np, 0, sizeof(*np));
2696                         np->shift = p->shift - CARDMAP_ORDER;
2697                         np->parent = p;
2698                         p->ptr[i] = np;
2699                 }
2700                 if (ptr == NULL)
2701                         clear_bit(i, &p->inuse);
2702                 p = p->ptr[i];
2703         }
2704         i = nr & CARDMAP_MASK;
2705         p->ptr[i] = ptr;
2706         if (ptr != NULL)
2707                 set_bit(i, &p->inuse);
2708         else
2709                 clear_bit(i, &p->inuse);
2710 }
2711
2712 static unsigned int cardmap_find_first_free(struct cardmap *map)
2713 {
2714         struct cardmap *p;
2715         unsigned int nr = 0;
2716         int i;
2717
2718         if ((p = map) == NULL)
2719                 return 0;
2720         for (;;) {
2721                 i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
2722                 if (i >= CARDMAP_WIDTH) {
2723                         if (p->parent == NULL)
2724                                 return CARDMAP_WIDTH << p->shift;
2725                         p = p->parent;
2726                         i = (nr >> p->shift) & CARDMAP_MASK;
2727                         set_bit(i, &p->inuse);
2728                         continue;
2729                 }
2730                 nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
2731                 if (p->shift == 0 || p->ptr[i] == NULL)
2732                         return nr;
2733                 p = p->ptr[i];
2734         }
2735 }
2736
2737 static void cardmap_destroy(struct cardmap **pmap)
2738 {
2739         struct cardmap *p, *np;
2740         int i;
2741
2742         for (p = *pmap; p != NULL; p = np) {
2743                 if (p->shift != 0) {
2744                         for (i = 0; i < CARDMAP_WIDTH; ++i)
2745                                 if (p->ptr[i] != NULL)
2746                                         break;
2747                         if (i < CARDMAP_WIDTH) {
2748                                 np = p->ptr[i];
2749                                 p->ptr[i] = NULL;
2750                                 continue;
2751                         }
2752                 }
2753                 np = p->parent;
2754                 kfree(p);
2755         }
2756         *pmap = NULL;
2757 }
2758
2759 /* Module/initialization stuff */
2760
2761 module_init(ppp_init);
2762 module_exit(ppp_cleanup);
2763
2764 EXPORT_SYMBOL(ppp_register_channel);
2765 EXPORT_SYMBOL(ppp_unregister_channel);
2766 EXPORT_SYMBOL(ppp_channel_index);
2767 EXPORT_SYMBOL(ppp_unit_number);
2768 EXPORT_SYMBOL(ppp_input);
2769 EXPORT_SYMBOL(ppp_input_error);
2770 EXPORT_SYMBOL(ppp_output_wakeup);
2771 EXPORT_SYMBOL(ppp_register_compressor);
2772 EXPORT_SYMBOL(ppp_unregister_compressor);
2773 MODULE_LICENSE("GPL");
2774 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2775 MODULE_ALIAS("/dev/ppp");