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

   1 /*
   2  * Generic PPP layer for Linux.
   3  *
   4  * Copyright 1999-2002 Paul Mackerras.
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  *
  11  * The generic PPP layer handles the PPP network interfaces, the
  12  * /dev/ppp device, packet and VJ compression, and multilink.
  13  * It talks to PPP `channels' via the interface defined in
  14  * include/linux/ppp_channel.h.  Channels provide the basic means for
  15  * sending and receiving PPP frames on some kind of communications
  16  * channel.
  17  *
  18  * Part of the code in this driver was inspired by the old async-only
  19  * PPP driver, written by Michael Callahan and Al Longyear, and
  20  * subsequently hacked by Paul Mackerras.
  21  *
  22  * ==FILEVERSION 20041108==
  23  */
  24
  25 #include <linux/module.h>
  26 #include <linux/kernel.h>
  27 #include <linux/kmod.h>
  28 #include <linux/init.h>
  29 #include <linux/list.h>
  30 #include <linux/netdevice.h>
  31 #include <linux/poll.h>
  32 #include <linux/ppp_defs.h>
  33 #include <linux/filter.h>
  34 #include <linux/if_ppp.h>
  35 #include <linux/ppp_channel.h>
  36 #include <linux/ppp-comp.h>
  37 #include <linux/skbuff.h>
  38 #include <linux/rtnetlink.h>
  39 #include <linux/if_arp.h>
  40 #include <linux/ip.h>
  41 #include <linux/tcp.h>
  42 #include <linux/spinlock.h>
  43 #include <linux/smp_lock.h>
  44 #include <linux/rwsem.h>
  45 #include <linux/stddef.h>
  46 #include <linux/device.h>
  47 #include <linux/mutex.h>
  48 #include <net/slhc_vj.h>
  49 #include <asm/atomic.h>
  50
  51 #define PPP_VERSION     "2.4.2"
  52
  53 /*
  54  * Network protocols we support.
  55  */
  56 #define NP_IP   0               /* Internet Protocol V4 */
  57 #define NP_IPV6 1               /* Internet Protocol V6 */
  58 #define NP_IPX  2               /* IPX protocol */
  59 #define NP_AT   3               /* Appletalk protocol */
  60 #define NP_MPLS_UC 4            /* MPLS unicast */
  61 #define NP_MPLS_MC 5            /* MPLS multicast */
  62 #define NUM_NP  6               /* Number of NPs. */
  63
  64 #define MPHDRLEN        6       /* multilink protocol header length */
  65 #define MPHDRLEN_SSN    4       /* ditto with short sequence numbers */
  66 #define MIN_FRAG_SIZE   64
  67
  68 /*
  69  * An instance of /dev/ppp can be associated with either a ppp
  70  * interface unit or a ppp channel.  In both cases, file->private_data
  71  * points to one of these.
  72  */
  73 struct ppp_file {
  74         enum {
  75                 INTERFACE=1, CHANNEL
  76         }               kind;
  77         struct sk_buff_head xq;         /* pppd transmit queue */
  78         struct sk_buff_head rq;         /* receive queue for pppd */
  79         wait_queue_head_t rwait;        /* for poll on reading /dev/ppp */
  80         atomic_t        refcnt;         /* # refs (incl /dev/ppp attached) */
  81         int             hdrlen;         /* space to leave for headers */
  82         int             index;          /* interface unit / channel number */
  83         int             dead;           /* unit/channel has been shut down */
  84 };
  85
  86 #define PF_TO_X(pf, X)          container_of(pf, X, file)
  87
  88 #define PF_TO_PPP(pf)           PF_TO_X(pf, struct ppp)
  89 #define PF_TO_CHANNEL(pf)       PF_TO_X(pf, struct channel)
  90
  91 /*
  92  * Data structure describing one ppp unit.
  93  * A ppp unit corresponds to a ppp network interface device
  94  * and represents a multilink bundle.
  95  * It can have 0 or more ppp channels connected to it.
  96  */
  97 struct ppp {
  98         struct ppp_file file;           /* stuff for read/write/poll 0 */
  99         struct file     *owner;         /* file that owns this unit 48 */
 100         struct list_head channels;      /* list of attached channels 4c */
 101         int             n_channels;     /* how many channels are attached 54 */
 102         spinlock_t      rlock;          /* lock for receive side 58 */
 103         spinlock_t      wlock;          /* lock for transmit side 5c */
 104         int             mru;            /* max receive unit 60 */
 105         unsigned int    flags;          /* control bits 64 */
 106         unsigned int    xstate;         /* transmit state bits 68 */
 107         unsigned int    rstate;         /* receive state bits 6c */
 108         int             debug;          /* debug flags 70 */
 109         struct slcompress *vj;          /* state for VJ header compression */
 110         enum NPmode     npmode[NUM_NP]; /* what to do with each net proto 78 */
 111         struct sk_buff  *xmit_pending;  /* a packet ready to go out 88 */
 112         struct compressor *xcomp;       /* transmit packet compressor 8c */
 113         void            *xc_state;      /* its internal state 90 */
 114         struct compressor *rcomp;       /* receive decompressor 94 */
 115         void            *rc_state;      /* its internal state 98 */
 116         unsigned long   last_xmit;      /* jiffies when last pkt sent 9c */
 117         unsigned long   last_recv;      /* jiffies when last pkt rcvd a0 */
 118         struct net_device *dev;         /* network interface device a4 */
 119 #ifdef CONFIG_PPP_MULTILINK
 120         int             nxchan;         /* next channel to send something on */
 121         u32             nxseq;          /* next sequence number to send */
 122         int             mrru;           /* MP: max reconst. receive unit */
 123         u32             nextseq;        /* MP: seq no of next packet */
 124         u32             minseq;         /* MP: min of most recent seqnos */
 125         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
 126 #endif /* CONFIG_PPP_MULTILINK */
 127         struct net_device_stats stats;  /* statistics */
 128 #ifdef CONFIG_PPP_FILTER
 129         struct sock_filter *pass_filter;        /* filter for packets to pass */
 130         struct sock_filter *active_filter;/* filter for pkts to reset idle */
 131         unsigned pass_len, active_len;
 132 #endif /* CONFIG_PPP_FILTER */
 133 };
 134
 135 /*
 136  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
 137  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
 138  * SC_MUST_COMP
 139  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
 140  * Bits in xstate: SC_COMP_RUN
 141  */
 142 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
 143                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
 144                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
 145
 146 /*
 147  * Private data structure for each channel.
 148  * This includes the data structure used for multilink.
 149  */
 150 struct channel {
 151         struct ppp_file file;           /* stuff for read/write/poll */
 152         struct list_head list;          /* link in all/new_channels list */
 153         struct ppp_channel *chan;       /* public channel data structure */
 154         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
 155         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
 156         struct ppp      *ppp;           /* ppp unit we're connected to */
 157         struct list_head clist;         /* link in list of channels per unit */
 158         rwlock_t        upl;            /* protects `ppp' */
 159 #ifdef CONFIG_PPP_MULTILINK
 160         u8              avail;          /* flag used in multilink stuff */
 161         u8              had_frag;       /* >= 1 fragments have been sent */
 162         u32             lastseq;        /* MP: last sequence # received */
 163 #endif /* CONFIG_PPP_MULTILINK */
 164 };
 165
 166 /*
 167  * SMP locking issues:
 168  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
 169  * list and the ppp.n_channels field, you need to take both locks
 170  * before you modify them.
 171  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
 172  * channel.downl.
 173  */
 174
 175 /*
 176  * A cardmap represents a mapping from unsigned integers to pointers,
 177  * and provides a fast "find lowest unused number" operation.
 178  * It uses a broad (32-way) tree with a bitmap at each level.
 179  * It is designed to be space-efficient for small numbers of entries
 180  * and time-efficient for large numbers of entries.
 181  */
 182 #define CARDMAP_ORDER   5
 183 #define CARDMAP_WIDTH   (1U << CARDMAP_ORDER)
 184 #define CARDMAP_MASK    (CARDMAP_WIDTH - 1)
 185
 186 struct cardmap {
 187         int shift;
 188         unsigned long inuse;
 189         struct cardmap *parent;
 190         void *ptr[CARDMAP_WIDTH];
 191 };
 192 static void *cardmap_get(struct cardmap *map, unsigned int nr);
 193 static int cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
 194 static unsigned int cardmap_find_first_free(struct cardmap *map);
 195 static void cardmap_destroy(struct cardmap **map);
 196
 197 /*
 198  * all_ppp_mutex protects the all_ppp_units mapping.
 199  * It also ensures that finding a ppp unit in the all_ppp_units map
 200  * and updating its file.refcnt field is atomic.
 201  */
 202 static DEFINE_MUTEX(all_ppp_mutex);
 203 static struct cardmap *all_ppp_units;
 204 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 205
 206 /*
 207  * all_channels_lock protects all_channels and last_channel_index,
 208  * and the atomicity of find a channel and updating its file.refcnt
 209  * field.
 210  */
 211 static DEFINE_SPINLOCK(all_channels_lock);
 212 static LIST_HEAD(all_channels);
 213 static LIST_HEAD(new_channels);
 214 static int last_channel_index;
 215 static atomic_t channel_count = ATOMIC_INIT(0);
 216
 217 /* Get the PPP protocol number from a skb */
 218 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
 219
 220 /* We limit the length of ppp->file.rq to this (arbitrary) value */
 221 #define PPP_MAX_RQLEN   32
 222
 223 /*
 224  * Maximum number of multilink fragments queued up.
 225  * This has to be large enough to cope with the maximum latency of
 226  * the slowest channel relative to the others.  Strictly it should
 227  * depend on the number of channels and their characteristics.
 228  */
 229 #define PPP_MP_MAX_QLEN 128
 230
 231 /* Multilink header bits. */
 232 #define B       0x80            /* this fragment begins a packet */
 233 #define E       0x40            /* this fragment ends a packet */
 234
 235 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
 236 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
 237 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
 238
 239 /* Prototypes. */
 240 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 241                                 unsigned int cmd, unsigned long arg);
 242 static void ppp_xmit_process(struct ppp *ppp);
 243 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
 244 static void ppp_push(struct ppp *ppp);
 245 static void ppp_channel_push(struct channel *pch);
 246 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
 247                               struct channel *pch);
 248 static void ppp_receive_error(struct ppp *ppp);
 249 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
 250 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
 251                                             struct sk_buff *skb);
 252 #ifdef CONFIG_PPP_MULTILINK
 253 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
 254                                 struct channel *pch);
 255 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
 256 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
 257 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
 258 #endif /* CONFIG_PPP_MULTILINK */
 259 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
 260 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
 261 static void ppp_ccp_closed(struct ppp *ppp);
 262 static struct compressor *find_compressor(int type);
 263 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
 264 static struct ppp *ppp_create_interface(int unit, int *retp);
 265 static void init_ppp_file(struct ppp_file *pf, int kind);
 266 static void ppp_shutdown_interface(struct ppp *ppp);
 267 static void ppp_destroy_interface(struct ppp *ppp);
 268 static struct ppp *ppp_find_unit(int unit);
 269 static struct channel *ppp_find_channel(int unit);
 270 static int ppp_connect_channel(struct channel *pch, int unit);
 271 static int ppp_disconnect_channel(struct channel *pch);
 272 static void ppp_destroy_channel(struct channel *pch);
 273
 274 static struct class *ppp_class;
 275
 276 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
 277 static inline int proto_to_npindex(int proto)
 278 {
 279         switch (proto) {
 280         case PPP_IP:
 281                 return NP_IP;
 282         case PPP_IPV6:
 283                 return NP_IPV6;
 284         case PPP_IPX:
 285                 return NP_IPX;
 286         case PPP_AT:
 287                 return NP_AT;
 288         case PPP_MPLS_UC:
 289                 return NP_MPLS_UC;
 290         case PPP_MPLS_MC:
 291                 return NP_MPLS_MC;
 292         }
 293         return -EINVAL;
 294 }
 295
 296 /* Translates an NP index into a PPP protocol number */
 297 static const int npindex_to_proto[NUM_NP] = {
 298         PPP_IP,
 299         PPP_IPV6,
 300         PPP_IPX,
 301         PPP_AT,
 302         PPP_MPLS_UC,
 303         PPP_MPLS_MC,
 304 };
 305
 306 /* Translates an ethertype into an NP index */
 307 static inline int ethertype_to_npindex(int ethertype)
 308 {
 309         switch (ethertype) {
 310         case ETH_P_IP:
 311                 return NP_IP;
 312         case ETH_P_IPV6:
 313                 return NP_IPV6;
 314         case ETH_P_IPX:
 315                 return NP_IPX;
 316         case ETH_P_PPPTALK:
 317         case ETH_P_ATALK:
 318                 return NP_AT;
 319         case ETH_P_MPLS_UC:
 320                 return NP_MPLS_UC;
 321         case ETH_P_MPLS_MC:
 322                 return NP_MPLS_MC;
 323         }
 324         return -1;
 325 }
 326
 327 /* Translates an NP index into an ethertype */
 328 static const int npindex_to_ethertype[NUM_NP] = {
 329         ETH_P_IP,
 330         ETH_P_IPV6,
 331         ETH_P_IPX,
 332         ETH_P_PPPTALK,
 333         ETH_P_MPLS_UC,
 334         ETH_P_MPLS_MC,
 335 };
 336
 337 /*
 338  * Locking shorthand.
 339  */
 340 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
 341 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
 342 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
 343 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
 344 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
 345                                      ppp_recv_lock(ppp); } while (0)
 346 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
 347                                      ppp_xmit_unlock(ppp); } while (0)
 348
 349 /*
 350  * /dev/ppp device routines.
 351  * The /dev/ppp device is used by pppd to control the ppp unit.
 352  * It supports the read, write, ioctl and poll functions.
 353  * Open instances of /dev/ppp can be in one of three states:
 354  * unattached, attached to a ppp unit, or attached to a ppp channel.
 355  */
 356 static int ppp_open(struct inode *inode, struct file *file)
 357 {
 358         /*
 359          * This could (should?) be enforced by the permissions on /dev/ppp.
 360          */
 361         if (!capable(CAP_NET_ADMIN))
 362                 return -EPERM;
 363         return 0;
 364 }
 365
 366 static int ppp_release(struct inode *inode, struct file *file)
 367 {
 368         struct ppp_file *pf = file->private_data;
 369         struct ppp *ppp;
 370
 371         if (pf != 0) {
 372                 file->private_data = NULL;
 373                 if (pf->kind == INTERFACE) {
 374                         ppp = PF_TO_PPP(pf);
 375                         if (file == ppp->owner)
 376                                 ppp_shutdown_interface(ppp);
 377                 }
 378                 if (atomic_dec_and_test(&pf->refcnt)) {
 379                         switch (pf->kind) {
 380                         case INTERFACE:
 381                                 ppp_destroy_interface(PF_TO_PPP(pf));
 382                                 break;
 383                         case CHANNEL:
 384                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
 385                                 break;
 386                         }
 387                 }
 388         }
 389         return 0;
 390 }
 391
 392 static ssize_t ppp_read(struct file *file, char __user *buf,
 393                         size_t count, loff_t *ppos)
 394 {
 395         struct ppp_file *pf = file->private_data;
 396         DECLARE_WAITQUEUE(wait, current);
 397         ssize_t ret;
 398         struct sk_buff *skb = NULL;
 399
 400         ret = count;
 401
 402         if (pf == 0)
 403                 return -ENXIO;
 404         add_wait_queue(&pf->rwait, &wait);
 405         for (;;) {
 406                 set_current_state(TASK_INTERRUPTIBLE);
 407                 skb = skb_dequeue(&pf->rq);
 408                 if (skb)
 409                         break;
 410                 ret = 0;
 411                 if (pf->dead)
 412                         break;
 413                 if (pf->kind == INTERFACE) {
 414                         /*
 415                          * Return 0 (EOF) on an interface that has no
 416                          * channels connected, unless it is looping
 417                          * network traffic (demand mode).
 418                          */
 419                         struct ppp *ppp = PF_TO_PPP(pf);
 420                         if (ppp->n_channels == 0
 421                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 422                                 break;
 423                 }
 424                 ret = -EAGAIN;
 425                 if (file->f_flags & O_NONBLOCK)
 426                         break;
 427                 ret = -ERESTARTSYS;
 428                 if (signal_pending(current))
 429                         break;
 430                 schedule();
 431         }
 432         set_current_state(TASK_RUNNING);
 433         remove_wait_queue(&pf->rwait, &wait);
 434
 435         if (skb == 0)
 436                 goto out;
 437
 438         ret = -EOVERFLOW;
 439         if (skb->len > count)
 440                 goto outf;
 441         ret = -EFAULT;
 442         if (copy_to_user(buf, skb->data, skb->len))
 443                 goto outf;
 444         ret = skb->len;
 445
 446  outf:
 447         kfree_skb(skb);
 448  out:
 449         return ret;
 450 }
 451
 452 static ssize_t ppp_write(struct file *file, const char __user *buf,
 453                          size_t count, loff_t *ppos)
 454 {
 455         struct ppp_file *pf = file->private_data;
 456         struct sk_buff *skb;
 457         ssize_t ret;
 458
 459         if (pf == 0)
 460                 return -ENXIO;
 461         ret = -ENOMEM;
 462         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
 463         if (skb == 0)
 464                 goto out;
 465         skb_reserve(skb, pf->hdrlen);
 466         ret = -EFAULT;
 467         if (copy_from_user(skb_put(skb, count), buf, count)) {
 468                 kfree_skb(skb);
 469                 goto out;
 470         }
 471
 472         skb_queue_tail(&pf->xq, skb);
 473
 474         switch (pf->kind) {
 475         case INTERFACE:
 476                 ppp_xmit_process(PF_TO_PPP(pf));
 477                 break;
 478         case CHANNEL:
 479                 ppp_channel_push(PF_TO_CHANNEL(pf));
 480                 break;
 481         }
 482
 483         ret = count;
 484
 485  out:
 486         return ret;
 487 }
 488
 489 /* No kernel lock - fine */
 490 static unsigned int ppp_poll(struct file *file, poll_table *wait)
 491 {
 492         struct ppp_file *pf = file->private_data;
 493         unsigned int mask;
 494
 495         if (pf == 0)
 496                 return 0;
 497         poll_wait(file, &pf->rwait, wait);
 498         mask = POLLOUT | POLLWRNORM;
 499         if (skb_peek(&pf->rq) != 0)
 500                 mask |= POLLIN | POLLRDNORM;
 501         if (pf->dead)
 502                 mask |= POLLHUP;
 503         else if (pf->kind == INTERFACE) {
 504                 /* see comment in ppp_read */
 505                 struct ppp *ppp = PF_TO_PPP(pf);
 506                 if (ppp->n_channels == 0
 507                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 508                         mask |= POLLIN | POLLRDNORM;
 509         }
 510
 511         return mask;
 512 }
 513
 514 #ifdef CONFIG_PPP_FILTER
 515 static int get_filter(void __user *arg, struct sock_filter **p)
 516 {
 517         struct sock_fprog uprog;
 518         struct sock_filter *code = NULL;
 519         int len, err;
 520
 521         if (copy_from_user(&uprog, arg, sizeof(uprog)))
 522                 return -EFAULT;
 523
 524         if (!uprog.len) {
 525                 *p = NULL;
 526                 return 0;
 527         }
 528
 529         len = uprog.len * sizeof(struct sock_filter);
 530         code = kmalloc(len, GFP_KERNEL);
 531         if (code == NULL)
 532                 return -ENOMEM;
 533
 534         if (copy_from_user(code, uprog.filter, len)) {
 535                 kfree(code);
 536                 return -EFAULT;
 537         }
 538
 539         err = sk_chk_filter(code, uprog.len);
 540         if (err) {
 541                 kfree(code);
 542                 return err;
 543         }
 544
 545         *p = code;
 546         return uprog.len;
 547 }
 548 #endif /* CONFIG_PPP_FILTER */
 549
 550 static int ppp_ioctl(struct inode *inode, struct file *file,
 551                      unsigned int cmd, unsigned long arg)
 552 {
 553         struct ppp_file *pf = file->private_data;
 554         struct ppp *ppp;
 555         int err = -EFAULT, val, val2, i;
 556         struct ppp_idle idle;
 557         struct npioctl npi;
 558         int unit, cflags;
 559         struct slcompress *vj;
 560         void __user *argp = (void __user *)arg;
 561         int __user *p = argp;
 562
 563         if (pf == 0)
 564                 return ppp_unattached_ioctl(pf, file, cmd, arg);
 565
 566         if (cmd == PPPIOCDETACH) {
 567                 /*
 568                  * We have to be careful here... if the file descriptor
 569                  * has been dup'd, we could have another process in the
 570                  * middle of a poll using the same file *, so we had
 571                  * better not free the interface data structures -
 572                  * instead we fail the ioctl.  Even in this case, we
 573                  * shut down the interface if we are the owner of it.
 574                  * Actually, we should get rid of PPPIOCDETACH, userland
 575                  * (i.e. pppd) could achieve the same effect by closing
 576                  * this fd and reopening /dev/ppp.
 577                  */
 578                 err = -EINVAL;
 579                 if (pf->kind == INTERFACE) {
 580                         ppp = PF_TO_PPP(pf);
 581                         if (file == ppp->owner)
 582                                 ppp_shutdown_interface(ppp);
 583                 }
 584                 if (atomic_read(&file->f_count) <= 2) {
 585                         ppp_release(inode, file);
 586                         err = 0;
 587                 } else
 588                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%d\n",
 589                                atomic_read(&file->f_count));
 590                 return err;
 591         }
 592
 593         if (pf->kind == CHANNEL) {
 594                 struct channel *pch = PF_TO_CHANNEL(pf);
 595                 struct ppp_channel *chan;
 596
 597                 switch (cmd) {
 598                 case PPPIOCCONNECT:
 599                         if (get_user(unit, p))
 600                                 break;
 601                         err = ppp_connect_channel(pch, unit);
 602                         break;
 603
 604                 case PPPIOCDISCONN:
 605                         err = ppp_disconnect_channel(pch);
 606                         break;
 607
 608                 default:
 609                         down_read(&pch->chan_sem);
 610                         chan = pch->chan;
 611                         err = -ENOTTY;
 612                         if (chan && chan->ops->ioctl)
 613                                 err = chan->ops->ioctl(chan, cmd, arg);
 614                         up_read(&pch->chan_sem);
 615                 }
 616                 return err;
 617         }
 618
 619         if (pf->kind != INTERFACE) {
 620                 /* can't happen */
 621                 printk(KERN_ERR "PPP: not interface or channel??\n");
 622                 return -EINVAL;
 623         }
 624
 625         ppp = PF_TO_PPP(pf);
 626         switch (cmd) {
 627         case PPPIOCSMRU:
 628                 if (get_user(val, p))
 629                         break;
 630                 ppp->mru = val;
 631                 err = 0;
 632                 break;
 633
 634         case PPPIOCSFLAGS:
 635                 if (get_user(val, p))
 636                         break;
 637                 ppp_lock(ppp);
 638                 cflags = ppp->flags & ~val;
 639                 ppp->flags = val & SC_FLAG_BITS;
 640                 ppp_unlock(ppp);
 641                 if (cflags & SC_CCP_OPEN)
 642                         ppp_ccp_closed(ppp);
 643                 err = 0;
 644                 break;
 645
 646         case PPPIOCGFLAGS:
 647                 val = ppp->flags | ppp->xstate | ppp->rstate;
 648                 if (put_user(val, p))
 649                         break;
 650                 err = 0;
 651                 break;
 652
 653         case PPPIOCSCOMPRESS:
 654                 err = ppp_set_compress(ppp, arg);
 655                 break;
 656
 657         case PPPIOCGUNIT:
 658                 if (put_user(ppp->file.index, p))
 659                         break;
 660                 err = 0;
 661                 break;
 662
 663         case PPPIOCSDEBUG:
 664                 if (get_user(val, p))
 665                         break;
 666                 ppp->debug = val;
 667                 err = 0;
 668                 break;
 669
 670         case PPPIOCGDEBUG:
 671                 if (put_user(ppp->debug, p))
 672                         break;
 673                 err = 0;
 674                 break;
 675
 676         case PPPIOCGIDLE:
 677                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 678                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
 679                 if (copy_to_user(argp, &idle, sizeof(idle)))
 680                         break;
 681                 err = 0;
 682                 break;
 683
 684         case PPPIOCSMAXCID:
 685                 if (get_user(val, p))
 686                         break;
 687                 val2 = 15;
 688                 if ((val >> 16) != 0) {
 689                         val2 = val >> 16;
 690                         val &= 0xffff;
 691                 }
 692                 vj = slhc_init(val2+1, val+1);
 693                 if (vj == 0) {
 694                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
 695                         err = -ENOMEM;
 696                         break;
 697                 }
 698                 ppp_lock(ppp);
 699                 if (ppp->vj != 0)
 700                         slhc_free(ppp->vj);
 701                 ppp->vj = vj;
 702                 ppp_unlock(ppp);
 703                 err = 0;
 704                 break;
 705
 706         case PPPIOCGNPMODE:
 707         case PPPIOCSNPMODE:
 708                 if (copy_from_user(&npi, argp, sizeof(npi)))
 709                         break;
 710                 err = proto_to_npindex(npi.protocol);
 711                 if (err < 0)
 712                         break;
 713                 i = err;
 714                 if (cmd == PPPIOCGNPMODE) {
 715                         err = -EFAULT;
 716                         npi.mode = ppp->npmode[i];
 717                         if (copy_to_user(argp, &npi, sizeof(npi)))
 718                                 break;
 719                 } else {
 720                         ppp->npmode[i] = npi.mode;
 721                         /* we may be able to transmit more packets now (??) */
 722                         netif_wake_queue(ppp->dev);
 723                 }
 724                 err = 0;
 725                 break;
 726
 727 #ifdef CONFIG_PPP_FILTER
 728         case PPPIOCSPASS:
 729         {
 730                 struct sock_filter *code;
 731                 err = get_filter(argp, &code);
 732                 if (err >= 0) {
 733                         ppp_lock(ppp);
 734                         kfree(ppp->pass_filter);
 735                         ppp->pass_filter = code;
 736                         ppp->pass_len = err;
 737                         ppp_unlock(ppp);
 738                         err = 0;
 739                 }
 740                 break;
 741         }
 742         case PPPIOCSACTIVE:
 743         {
 744                 struct sock_filter *code;
 745                 err = get_filter(argp, &code);
 746                 if (err >= 0) {
 747                         ppp_lock(ppp);
 748                         kfree(ppp->active_filter);
 749                         ppp->active_filter = code;
 750                         ppp->active_len = err;
 751                         ppp_unlock(ppp);
 752                         err = 0;
 753                 }
 754                 break;
 755         }
 756 #endif /* CONFIG_PPP_FILTER */
 757
 758 #ifdef CONFIG_PPP_MULTILINK
 759         case PPPIOCSMRRU:
 760                 if (get_user(val, p))
 761                         break;
 762                 ppp_recv_lock(ppp);
 763                 ppp->mrru = val;
 764                 ppp_recv_unlock(ppp);
 765                 err = 0;
 766                 break;
 767 #endif /* CONFIG_PPP_MULTILINK */
 768
 769         default:
 770                 err = -ENOTTY;
 771         }
 772
 773         return err;
 774 }
 775
 776 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 777                                 unsigned int cmd, unsigned long arg)
 778 {
 779         int unit, err = -EFAULT;
 780         struct ppp *ppp;
 781         struct channel *chan;
 782         int __user *p = (int __user *)arg;
 783
 784         switch (cmd) {
 785         case PPPIOCNEWUNIT:
 786                 /* Create a new ppp unit */
 787                 if (get_user(unit, p))
 788                         break;
 789                 ppp = ppp_create_interface(unit, &err);
 790                 if (ppp == 0)
 791                         break;
 792                 file->private_data = &ppp->file;
 793                 ppp->owner = file;
 794                 err = -EFAULT;
 795                 if (put_user(ppp->file.index, p))
 796                         break;
 797                 err = 0;
 798                 break;
 799
 800         case PPPIOCATTACH:
 801                 /* Attach to an existing ppp unit */
 802                 if (get_user(unit, p))
 803                         break;
 804                 mutex_lock(&all_ppp_mutex);
 805                 err = -ENXIO;
 806                 ppp = ppp_find_unit(unit);
 807                 if (ppp != 0) {
 808                         atomic_inc(&ppp->file.refcnt);
 809                         file->private_data = &ppp->file;
 810                         err = 0;
 811                 }
 812                 mutex_unlock(&all_ppp_mutex);
 813                 break;
 814
 815         case PPPIOCATTCHAN:
 816                 if (get_user(unit, p))
 817                         break;
 818                 spin_lock_bh(&all_channels_lock);
 819                 err = -ENXIO;
 820                 chan = ppp_find_channel(unit);
 821                 if (chan != 0) {
 822                         atomic_inc(&chan->file.refcnt);
 823                         file->private_data = &chan->file;
 824                         err = 0;
 825                 }
 826                 spin_unlock_bh(&all_channels_lock);
 827                 break;
 828
 829         default:
 830                 err = -ENOTTY;
 831         }
 832         return err;
 833 }
 834
 835 static const struct file_operations ppp_device_fops = {
 836         .owner          = THIS_MODULE,
 837         .read           = ppp_read,
 838         .write          = ppp_write,
 839         .poll           = ppp_poll,
 840         .ioctl          = ppp_ioctl,
 841         .open           = ppp_open,
 842         .release        = ppp_release
 843 };
 844
 845 #define PPP_MAJOR       108
 846
 847 /* Called at boot time if ppp is compiled into the kernel,
 848    or at module load time (from init_module) if compiled as a module. */
 849 static int __init ppp_init(void)
 850 {
 851         int err;
 852
 853         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
 854         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
 855         if (!err) {
 856                 ppp_class = class_create(THIS_MODULE, "ppp");
 857                 if (IS_ERR(ppp_class)) {
 858                         err = PTR_ERR(ppp_class);
 859                         goto out_chrdev;
 860                 }
 861                 device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), "ppp");
 862         }
 863
 864 out:
 865         if (err)
 866                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
 867         return err;
 868
 869 out_chrdev:
 870         unregister_chrdev(PPP_MAJOR, "ppp");
 871         goto out;
 872 }
 873
 874 /*
 875  * Network interface unit routines.
 876  */
 877 static int
 878 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 879 {
 880         struct ppp *ppp = (struct ppp *) dev->priv;
 881         int npi, proto;
 882         unsigned char *pp;
 883
 884         npi = ethertype_to_npindex(ntohs(skb->protocol));
 885         if (npi < 0)
 886                 goto outf;
 887
 888         /* Drop, accept or reject the packet */
 889         switch (ppp->npmode[npi]) {
 890         case NPMODE_PASS:
 891                 break;
 892         case NPMODE_QUEUE:
 893                 /* it would be nice to have a way to tell the network
 894                    system to queue this one up for later. */
 895                 goto outf;
 896         case NPMODE_DROP:
 897         case NPMODE_ERROR:
 898                 goto outf;
 899         }
 900
 901         /* Put the 2-byte PPP protocol number on the front,
 902            making sure there is room for the address and control fields. */
 903         if (skb_headroom(skb) < PPP_HDRLEN) {
 904                 struct sk_buff *ns;
 905
 906                 ns = alloc_skb(skb->len + dev->hard_header_len, GFP_ATOMIC);
 907                 if (ns == 0)
 908                         goto outf;
 909                 skb_reserve(ns, dev->hard_header_len);
 910                 skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
 911                 kfree_skb(skb);
 912                 skb = ns;
 913         }
 914         pp = skb_push(skb, 2);
 915         proto = npindex_to_proto[npi];
 916         pp[0] = proto >> 8;
 917         pp[1] = proto;
 918
 919         netif_stop_queue(dev);
 920         skb_queue_tail(&ppp->file.xq, skb);
 921         ppp_xmit_process(ppp);
 922         return 0;
 923
 924  outf:
 925         kfree_skb(skb);
 926         ++ppp->stats.tx_dropped;
 927         return 0;
 928 }
 929
 930 static struct net_device_stats *
 931 ppp_net_stats(struct net_device *dev)
 932 {
 933         struct ppp *ppp = (struct ppp *) dev->priv;
 934
 935         return &ppp->stats;
 936 }
 937
 938 static int
 939 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 940 {
 941         struct ppp *ppp = dev->priv;
 942         int err = -EFAULT;
 943         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
 944         struct ppp_stats stats;
 945         struct ppp_comp_stats cstats;
 946         char *vers;
 947
 948         switch (cmd) {
 949         case SIOCGPPPSTATS:
 950                 ppp_get_stats(ppp, &stats);
 951                 if (copy_to_user(addr, &stats, sizeof(stats)))
 952                         break;
 953                 err = 0;
 954                 break;
 955
 956         case SIOCGPPPCSTATS:
 957                 memset(&cstats, 0, sizeof(cstats));
 958                 if (ppp->xc_state != 0)
 959                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
 960                 if (ppp->rc_state != 0)
 961                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
 962                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
 963                         break;
 964                 err = 0;
 965                 break;
 966
 967         case SIOCGPPPVER:
 968                 vers = PPP_VERSION;
 969                 if (copy_to_user(addr, vers, strlen(vers) + 1))
 970                         break;
 971                 err = 0;
 972                 break;
 973
 974         default:
 975                 err = -EINVAL;
 976         }
 977
 978         return err;
 979 }
 980
 981 static void ppp_setup(struct net_device *dev)
 982 {
 983         dev->hard_header_len = PPP_HDRLEN;
 984         dev->mtu = PPP_MTU;
 985         dev->addr_len = 0;
 986         dev->tx_queue_len = 3;
 987         dev->type = ARPHRD_PPP;
 988         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
 989 }
 990
 991 /*
 992  * Transmit-side routines.
 993  */
 994
 995 /*
 996  * Called to do any work queued up on the transmit side
 997  * that can now be done.
 998  */
 999 static void
1000 ppp_xmit_process(struct ppp *ppp)
1001 {
1002         struct sk_buff *skb;
1003
1004         ppp_xmit_lock(ppp);
1005         if (ppp->dev != 0) {
1006                 ppp_push(ppp);
1007                 while (ppp->xmit_pending == 0
1008                        && (skb = skb_dequeue(&ppp->file.xq)) != 0)
1009                         ppp_send_frame(ppp, skb);
1010                 /* If there's no work left to do, tell the core net
1011                    code that we can accept some more. */
1012                 if (ppp->xmit_pending == 0 && skb_peek(&ppp->file.xq) == 0)
1013                         netif_wake_queue(ppp->dev);
1014         }
1015         ppp_xmit_unlock(ppp);
1016 }
1017
1018 static inline struct sk_buff *
1019 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1020 {
1021         struct sk_buff *new_skb;
1022         int len;
1023         int new_skb_size = ppp->dev->mtu +
1024                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1025         int compressor_skb_size = ppp->dev->mtu +
1026                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1027         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1028         if (!new_skb) {
1029                 if (net_ratelimit())
1030                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1031                 return NULL;
1032         }
1033         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1034                 skb_reserve(new_skb,
1035                             ppp->dev->hard_header_len - PPP_HDRLEN);
1036
1037         /* compressor still expects A/C bytes in hdr */
1038         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1039                                    new_skb->data, skb->len + 2,
1040                                    compressor_skb_size);
1041         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1042                 kfree_skb(skb);
1043                 skb = new_skb;
1044                 skb_put(skb, len);
1045                 skb_pull(skb, 2);       /* pull off A/C bytes */
1046         } else if (len == 0) {
1047                 /* didn't compress, or CCP not up yet */
1048                 kfree_skb(new_skb);
1049                 new_skb = skb;
1050         } else {
1051                 /*
1052                  * (len < 0)
1053                  * MPPE requires that we do not send unencrypted
1054                  * frames.  The compressor will return -1 if we
1055                  * should drop the frame.  We cannot simply test
1056                  * the compress_proto because MPPE and MPPC share
1057                  * the same number.
1058                  */
1059                 if (net_ratelimit())
1060                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1061                 kfree_skb(skb);
1062                 kfree_skb(new_skb);
1063                 new_skb = NULL;
1064         }
1065         return new_skb;
1066 }
1067
1068 /*
1069  * Compress and send a frame.
1070  * The caller should have locked the xmit path,
1071  * and xmit_pending should be 0.
1072  */
1073 static void
1074 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1075 {
1076         int proto = PPP_PROTO(skb);
1077         struct sk_buff *new_skb;
1078         int len;
1079         unsigned char *cp;
1080
1081         if (proto < 0x8000) {
1082 #ifdef CONFIG_PPP_FILTER
1083                 /* check if we should pass this packet */
1084                 /* the filter instructions are constructed assuming
1085                    a four-byte PPP header on each packet */
1086                 *skb_push(skb, 2) = 1;
1087                 if (ppp->pass_filter
1088                     && sk_run_filter(skb, ppp->pass_filter,
1089                                      ppp->pass_len) == 0) {
1090                         if (ppp->debug & 1)
1091                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1092                         kfree_skb(skb);
1093                         return;
1094                 }
1095                 /* if this packet passes the active filter, record the time */
1096                 if (!(ppp->active_filter
1097                       && sk_run_filter(skb, ppp->active_filter,
1098                                        ppp->active_len) == 0))
1099                         ppp->last_xmit = jiffies;
1100                 skb_pull(skb, 2);
1101 #else
1102                 /* for data packets, record the time */
1103                 ppp->last_xmit = jiffies;
1104 #endif /* CONFIG_PPP_FILTER */
1105         }
1106
1107         ++ppp->stats.tx_packets;
1108         ppp->stats.tx_bytes += skb->len - 2;
1109
1110         switch (proto) {
1111         case PPP_IP:
1112                 if (ppp->vj == 0 || (ppp->flags & SC_COMP_TCP) == 0)
1113                         break;
1114                 /* try to do VJ TCP header compression */
1115                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1116                                     GFP_ATOMIC);
1117                 if (new_skb == 0) {
1118                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1119                         goto drop;
1120                 }
1121                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1122                 cp = skb->data + 2;
1123                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1124                                     new_skb->data + 2, &cp,
1125                                     !(ppp->flags & SC_NO_TCP_CCID));
1126                 if (cp == skb->data + 2) {
1127                         /* didn't compress */
1128                         kfree_skb(new_skb);
1129                 } else {
1130                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1131                                 proto = PPP_VJC_COMP;
1132                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1133                         } else {
1134                                 proto = PPP_VJC_UNCOMP;
1135                                 cp[0] = skb->data[2];
1136                         }
1137                         kfree_skb(skb);
1138                         skb = new_skb;
1139                         cp = skb_put(skb, len + 2);
1140                         cp[0] = 0;
1141                         cp[1] = proto;
1142                 }
1143                 break;
1144
1145         case PPP_CCP:
1146                 /* peek at outbound CCP frames */
1147                 ppp_ccp_peek(ppp, skb, 0);
1148                 break;
1149         }
1150
1151         /* try to do packet compression */
1152         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0
1153             && proto != PPP_LCP && proto != PPP_CCP) {
1154                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1155                         if (net_ratelimit())
1156                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1157                         goto drop;
1158                 }
1159                 skb = pad_compress_skb(ppp, skb);
1160                 if (!skb)
1161                         goto drop;
1162         }
1163
1164         /*
1165          * If we are waiting for traffic (demand dialling),
1166          * queue it up for pppd to receive.
1167          */
1168         if (ppp->flags & SC_LOOP_TRAFFIC) {
1169                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1170                         goto drop;
1171                 skb_queue_tail(&ppp->file.rq, skb);
1172                 wake_up_interruptible(&ppp->file.rwait);
1173                 return;
1174         }
1175
1176         ppp->xmit_pending = skb;
1177         ppp_push(ppp);
1178         return;
1179
1180  drop:
1181         if (skb)
1182                 kfree_skb(skb);
1183         ++ppp->stats.tx_errors;
1184 }
1185
1186 /*
1187  * Try to send the frame in xmit_pending.
1188  * The caller should have the xmit path locked.
1189  */
1190 static void
1191 ppp_push(struct ppp *ppp)
1192 {
1193         struct list_head *list;
1194         struct channel *pch;
1195         struct sk_buff *skb = ppp->xmit_pending;
1196
1197         if (skb == 0)
1198                 return;
1199
1200         list = &ppp->channels;
1201         if (list_empty(list)) {
1202                 /* nowhere to send the packet, just drop it */
1203                 ppp->xmit_pending = NULL;
1204                 kfree_skb(skb);
1205                 return;
1206         }
1207
1208         if ((ppp->flags & SC_MULTILINK) == 0) {
1209                 /* not doing multilink: send it down the first channel */
1210                 list = list->next;
1211                 pch = list_entry(list, struct channel, clist);
1212
1213                 spin_lock_bh(&pch->downl);
1214                 if (pch->chan) {
1215                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1216                                 ppp->xmit_pending = NULL;
1217                 } else {
1218                         /* channel got unregistered */
1219                         kfree_skb(skb);
1220                         ppp->xmit_pending = NULL;
1221                 }
1222                 spin_unlock_bh(&pch->downl);
1223                 return;
1224         }
1225
1226 #ifdef CONFIG_PPP_MULTILINK
1227         /* Multilink: fragment the packet over as many links
1228            as can take the packet at the moment. */
1229         if (!ppp_mp_explode(ppp, skb))
1230                 return;
1231 #endif /* CONFIG_PPP_MULTILINK */
1232
1233         ppp->xmit_pending = NULL;
1234         kfree_skb(skb);
1235 }
1236
1237 #ifdef CONFIG_PPP_MULTILINK
1238 /*
1239  * Divide a packet to be transmitted into fragments and
1240  * send them out the individual links.
1241  */
1242 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1243 {
1244         int len, fragsize;
1245         int i, bits, hdrlen, mtu;
1246         int flen;
1247         int navail, nfree;
1248         int nbigger;
1249         unsigned char *p, *q;
1250         struct list_head *list;
1251         struct channel *pch;
1252         struct sk_buff *frag;
1253         struct ppp_channel *chan;
1254
1255         nfree = 0;      /* # channels which have no packet already queued */
1256         navail = 0;     /* total # of usable channels (not deregistered) */
1257         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1258         i = 0;
1259         list_for_each_entry(pch, &ppp->channels, clist) {
1260                 navail += pch->avail = (pch->chan != NULL);
1261                 if (pch->avail) {
1262                         if (skb_queue_empty(&pch->file.xq) ||
1263                             !pch->had_frag) {
1264                                 pch->avail = 2;
1265                                 ++nfree;
1266                         }
1267                         if (!pch->had_frag && i < ppp->nxchan)
1268                                 ppp->nxchan = i;
1269                 }
1270                 ++i;
1271         }
1272
1273         /*
1274          * Don't start sending this packet unless at least half of
1275          * the channels are free.  This gives much better TCP
1276          * performance if we have a lot of channels.
1277          */
1278         if (nfree == 0 || nfree < navail / 2)
1279                 return 0;       /* can't take now, leave it in xmit_pending */
1280
1281         /* Do protocol field compression (XXX this should be optional) */
1282         p = skb->data;
1283         len = skb->len;
1284         if (*p == 0) {
1285                 ++p;
1286                 --len;
1287         }
1288
1289         /*
1290          * Decide on fragment size.
1291          * We create a fragment for each free channel regardless of
1292          * how small they are (i.e. even 0 length) in order to minimize
1293          * the time that it will take to detect when a channel drops
1294          * a fragment.
1295          */
1296         fragsize = len;
1297         if (nfree > 1)
1298                 fragsize = DIV_ROUND_UP(fragsize, nfree);
1299         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1300            except if nbigger==0, then they all get fragsize. */
1301         nbigger = len % nfree;
1302
1303         /* skip to the channel after the one we last used
1304            and start at that one */
1305         list = &ppp->channels;
1306         for (i = 0; i < ppp->nxchan; ++i) {
1307                 list = list->next;
1308                 if (list == &ppp->channels) {
1309                         i = 0;
1310                         break;
1311                 }
1312         }
1313
1314         /* create a fragment for each channel */
1315         bits = B;
1316         while (nfree > 0 || len > 0) {
1317                 list = list->next;
1318                 if (list == &ppp->channels) {
1319                         i = 0;
1320                         continue;
1321                 }
1322                 pch = list_entry(list, struct channel, clist);
1323                 ++i;
1324                 if (!pch->avail)
1325                         continue;
1326
1327                 /*
1328                  * Skip this channel if it has a fragment pending already and
1329                  * we haven't given a fragment to all of the free channels.
1330                  */
1331                 if (pch->avail == 1) {
1332                         if (nfree > 0)
1333                                 continue;
1334                 } else {
1335                         --nfree;
1336                         pch->avail = 1;
1337                 }
1338
1339                 /* check the channel's mtu and whether it is still attached. */
1340                 spin_lock_bh(&pch->downl);
1341                 if (pch->chan == NULL) {
1342                         /* can't use this channel, it's being deregistered */
1343                         spin_unlock_bh(&pch->downl);
1344                         pch->avail = 0;
1345                         if (--navail == 0)
1346                                 break;
1347                         continue;
1348                 }
1349
1350                 /*
1351                  * Create a fragment for this channel of
1352                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1353                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1354                  * MTU, so we use mtu = 2 + hdrlen.
1355                  */
1356                 if (fragsize > len)
1357                         fragsize = len;
1358                 flen = fragsize;
1359                 mtu = pch->chan->mtu + 2 - hdrlen;
1360                 if (mtu < 4)
1361                         mtu = 4;
1362                 if (flen > mtu)
1363                         flen = mtu;
1364                 if (flen == len && nfree == 0)
1365                         bits |= E;
1366                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1367                 if (frag == 0)
1368                         goto noskb;
1369                 q = skb_put(frag, flen + hdrlen);
1370
1371                 /* make the MP header */
1372                 q[0] = PPP_MP >> 8;
1373                 q[1] = PPP_MP;
1374                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1375                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1376                         q[3] = ppp->nxseq;
1377                 } else {
1378                         q[2] = bits;
1379                         q[3] = ppp->nxseq >> 16;
1380                         q[4] = ppp->nxseq >> 8;
1381                         q[5] = ppp->nxseq;
1382                 }
1383
1384                 /*
1385                  * Copy the data in.
1386                  * Unfortunately there is a bug in older versions of
1387                  * the Linux PPP multilink reconstruction code where it
1388                  * drops 0-length fragments.  Therefore we make sure the
1389                  * fragment has at least one byte of data.  Any bytes
1390                  * we add in this situation will end up as padding on the
1391                  * end of the reconstructed packet.
1392                  */
1393                 if (flen == 0)
1394                         *skb_put(frag, 1) = 0;
1395                 else
1396                         memcpy(q + hdrlen, p, flen);
1397
1398                 /* try to send it down the channel */
1399                 chan = pch->chan;
1400                 if (!skb_queue_empty(&pch->file.xq) ||
1401                     !chan->ops->start_xmit(chan, frag))
1402                         skb_queue_tail(&pch->file.xq, frag);
1403                 pch->had_frag = 1;
1404                 p += flen;
1405                 len -= flen;
1406                 ++ppp->nxseq;
1407                 bits = 0;
1408                 spin_unlock_bh(&pch->downl);
1409
1410                 if (--nbigger == 0 && fragsize > 0)
1411                         --fragsize;
1412         }
1413         ppp->nxchan = i;
1414
1415         return 1;
1416
1417  noskb:
1418         spin_unlock_bh(&pch->downl);
1419         if (ppp->debug & 1)
1420                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1421         ++ppp->stats.tx_errors;
1422         ++ppp->nxseq;
1423         return 1;       /* abandon the frame */
1424 }
1425 #endif /* CONFIG_PPP_MULTILINK */
1426
1427 /*
1428  * Try to send data out on a channel.
1429  */
1430 static void
1431 ppp_channel_push(struct channel *pch)
1432 {
1433         struct sk_buff *skb;
1434         struct ppp *ppp;
1435
1436         spin_lock_bh(&pch->downl);
1437         if (pch->chan != 0) {
1438                 while (!skb_queue_empty(&pch->file.xq)) {
1439                         skb = skb_dequeue(&pch->file.xq);
1440                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1441                                 /* put the packet back and try again later */
1442                                 skb_queue_head(&pch->file.xq, skb);
1443                                 break;
1444                         }
1445                 }
1446         } else {
1447                 /* channel got deregistered */
1448                 skb_queue_purge(&pch->file.xq);
1449         }
1450         spin_unlock_bh(&pch->downl);
1451         /* see if there is anything from the attached unit to be sent */
1452         if (skb_queue_empty(&pch->file.xq)) {
1453                 read_lock_bh(&pch->upl);
1454                 ppp = pch->ppp;
1455                 if (ppp != 0)
1456                         ppp_xmit_process(ppp);
1457                 read_unlock_bh(&pch->upl);
1458         }
1459 }
1460
1461 /*
1462  * Receive-side routines.
1463  */
1464
1465 /* misuse a few fields of the skb for MP reconstruction */
1466 #define sequence        priority
1467 #define BEbits          cb[0]
1468
1469 static inline void
1470 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1471 {
1472         ppp_recv_lock(ppp);
1473         /* ppp->dev == 0 means interface is closing down */
1474         if (ppp->dev != 0)
1475                 ppp_receive_frame(ppp, skb, pch);
1476         else
1477                 kfree_skb(skb);
1478         ppp_recv_unlock(ppp);
1479 }
1480
1481 void
1482 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1483 {
1484         struct channel *pch = chan->ppp;
1485         int proto;
1486
1487         if (pch == 0 || skb->len == 0) {
1488                 kfree_skb(skb);
1489                 return;
1490         }
1491
1492         proto = PPP_PROTO(skb);
1493         read_lock_bh(&pch->upl);
1494         if (pch->ppp == 0 || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1495                 /* put it on the channel queue */
1496                 skb_queue_tail(&pch->file.rq, skb);
1497                 /* drop old frames if queue too long */
1498                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1499                        && (skb = skb_dequeue(&pch->file.rq)) != 0)
1500                         kfree_skb(skb);
1501                 wake_up_interruptible(&pch->file.rwait);
1502         } else {
1503                 ppp_do_recv(pch->ppp, skb, pch);
1504         }
1505         read_unlock_bh(&pch->upl);
1506 }
1507
1508 /* Put a 0-length skb in the receive queue as an error indication */
1509 void
1510 ppp_input_error(struct ppp_channel *chan, int code)
1511 {
1512         struct channel *pch = chan->ppp;
1513         struct sk_buff *skb;
1514
1515         if (pch == 0)
1516                 return;
1517
1518         read_lock_bh(&pch->upl);
1519         if (pch->ppp != 0) {
1520                 skb = alloc_skb(0, GFP_ATOMIC);
1521                 if (skb != 0) {
1522                         skb->len = 0;           /* probably unnecessary */
1523                         skb->cb[0] = code;
1524                         ppp_do_recv(pch->ppp, skb, pch);
1525                 }
1526         }
1527         read_unlock_bh(&pch->upl);
1528 }
1529
1530 /*
1531  * We come in here to process a received frame.
1532  * The receive side of the ppp unit is locked.
1533  */
1534 static void
1535 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1536 {
1537         if (skb->len >= 2) {
1538 #ifdef CONFIG_PPP_MULTILINK
1539                 /* XXX do channel-level decompression here */
1540                 if (PPP_PROTO(skb) == PPP_MP)
1541                         ppp_receive_mp_frame(ppp, skb, pch);
1542                 else
1543 #endif /* CONFIG_PPP_MULTILINK */
1544                         ppp_receive_nonmp_frame(ppp, skb);
1545                 return;
1546         }
1547
1548         if (skb->len > 0)
1549                 /* note: a 0-length skb is used as an error indication */
1550                 ++ppp->stats.rx_length_errors;
1551
1552         kfree_skb(skb);
1553         ppp_receive_error(ppp);
1554 }
1555
1556 static void
1557 ppp_receive_error(struct ppp *ppp)
1558 {
1559         ++ppp->stats.rx_errors;
1560         if (ppp->vj != 0)
1561                 slhc_toss(ppp->vj);
1562 }
1563
1564 static void
1565 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1566 {
1567         struct sk_buff *ns;
1568         int proto, len, npi;
1569
1570         /*
1571          * Decompress the frame, if compressed.
1572          * Note that some decompressors need to see uncompressed frames
1573          * that come in as well as compressed frames.
1574          */
1575         if (ppp->rc_state != 0 && (ppp->rstate & SC_DECOMP_RUN)
1576             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1577                 skb = ppp_decompress_frame(ppp, skb);
1578
1579         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1580                 goto err;
1581
1582         proto = PPP_PROTO(skb);
1583         switch (proto) {
1584         case PPP_VJC_COMP:
1585                 /* decompress VJ compressed packets */
1586                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1587                         goto err;
1588
1589                 if (skb_tailroom(skb) < 124) {
1590                         /* copy to a new sk_buff with more tailroom */
1591                         ns = dev_alloc_skb(skb->len + 128);
1592                         if (ns == 0) {
1593                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1594                                 goto err;
1595                         }
1596                         skb_reserve(ns, 2);
1597                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1598                         kfree_skb(skb);
1599                         skb = ns;
1600                 }
1601                 else
1602                         skb->ip_summed = CHECKSUM_NONE;
1603
1604                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1605                 if (len <= 0) {
1606                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1607                         goto err;
1608                 }
1609                 len += 2;
1610                 if (len > skb->len)
1611                         skb_put(skb, len - skb->len);
1612                 else if (len < skb->len)
1613                         skb_trim(skb, len);
1614                 proto = PPP_IP;
1615                 break;
1616
1617         case PPP_VJC_UNCOMP:
1618                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1619                         goto err;
1620
1621                 /* Until we fix the decompressor need to make sure
1622                  * data portion is linear.
1623                  */
1624                 if (!pskb_may_pull(skb, skb->len))
1625                         goto err;
1626
1627                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1628                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1629                         goto err;
1630                 }
1631                 proto = PPP_IP;
1632                 break;
1633
1634         case PPP_CCP:
1635                 ppp_ccp_peek(ppp, skb, 1);
1636                 break;
1637         }
1638
1639         ++ppp->stats.rx_packets;
1640         ppp->stats.rx_bytes += skb->len - 2;
1641
1642         npi = proto_to_npindex(proto);
1643         if (npi < 0) {
1644                 /* control or unknown frame - pass it to pppd */
1645                 skb_queue_tail(&ppp->file.rq, skb);
1646                 /* limit queue length by dropping old frames */
1647                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1648                        && (skb = skb_dequeue(&ppp->file.rq)) != 0)
1649                         kfree_skb(skb);
1650                 /* wake up any process polling or blocking on read */
1651                 wake_up_interruptible(&ppp->file.rwait);
1652
1653         } else {
1654                 /* network protocol frame - give it to the kernel */
1655
1656 #ifdef CONFIG_PPP_FILTER
1657                 /* check if the packet passes the pass and active filters */
1658                 /* the filter instructions are constructed assuming
1659                    a four-byte PPP header on each packet */
1660                 *skb_push(skb, 2) = 0;
1661                 if (ppp->pass_filter
1662                     && sk_run_filter(skb, ppp->pass_filter,
1663                                      ppp->pass_len) == 0) {
1664                         if (ppp->debug & 1)
1665                                 printk(KERN_DEBUG "PPP: inbound frame not passed\n");
1666                         kfree_skb(skb);
1667                         return;
1668                 }
1669                 if (!(ppp->active_filter
1670                       && sk_run_filter(skb, ppp->active_filter,
1671                                        ppp->active_len) == 0))
1672                         ppp->last_recv = jiffies;
1673                 skb_pull(skb, 2);
1674 #else
1675                 ppp->last_recv = jiffies;
1676 #endif /* CONFIG_PPP_FILTER */
1677
1678                 if ((ppp->dev->flags & IFF_UP) == 0
1679                     || ppp->npmode[npi] != NPMODE_PASS) {
1680                         kfree_skb(skb);
1681                 } else {
1682                         /* chop off protocol */
1683                         skb_pull_rcsum(skb, 2);
1684                         skb->dev = ppp->dev;
1685                         skb->protocol = htons(npindex_to_ethertype[npi]);
1686                         skb_reset_mac_header(skb);
1687                         netif_rx(skb);
1688                         ppp->dev->last_rx = jiffies;
1689                 }
1690         }
1691         return;
1692
1693  err:
1694         kfree_skb(skb);
1695         ppp_receive_error(ppp);
1696 }
1697
1698 static struct sk_buff *
1699 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1700 {
1701         int proto = PPP_PROTO(skb);
1702         struct sk_buff *ns;
1703         int len;
1704
1705         /* Until we fix all the decompressor's need to make sure
1706          * data portion is linear.
1707          */
1708         if (!pskb_may_pull(skb, skb->len))
1709                 goto err;
1710
1711         if (proto == PPP_COMP) {
1712                 ns = dev_alloc_skb(ppp->mru + PPP_HDRLEN);
1713                 if (ns == 0) {
1714                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1715                         goto err;
1716                 }
1717                 /* the decompressor still expects the A/C bytes in the hdr */
1718                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1719                                 skb->len + 2, ns->data, ppp->mru + PPP_HDRLEN);
1720                 if (len < 0) {
1721                         /* Pass the compressed frame to pppd as an
1722                            error indication. */
1723                         if (len == DECOMP_FATALERROR)
1724                                 ppp->rstate |= SC_DC_FERROR;
1725                         kfree_skb(ns);
1726                         goto err;
1727                 }
1728
1729                 kfree_skb(skb);
1730                 skb = ns;
1731                 skb_put(skb, len);
1732                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1733
1734         } else {
1735                 /* Uncompressed frame - pass to decompressor so it
1736                    can update its dictionary if necessary. */
1737                 if (ppp->rcomp->incomp)
1738                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1739                                            skb->len + 2);
1740         }
1741
1742         return skb;
1743
1744  err:
1745         ppp->rstate |= SC_DC_ERROR;
1746         ppp_receive_error(ppp);
1747         return skb;
1748 }
1749
1750 #ifdef CONFIG_PPP_MULTILINK
1751 /*
1752  * Receive a multilink frame.
1753  * We put it on the reconstruction queue and then pull off
1754  * as many completed frames as we can.
1755  */
1756 static void
1757 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1758 {
1759         u32 mask, seq;
1760         struct channel *ch;
1761         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1762
1763         if (!pskb_may_pull(skb, mphdrlen) || ppp->mrru == 0)
1764                 goto err;               /* no good, throw it away */
1765
1766         /* Decode sequence number and begin/end bits */
1767         if (ppp->flags & SC_MP_SHORTSEQ) {
1768                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1769                 mask = 0xfff;
1770         } else {
1771                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1772                 mask = 0xffffff;
1773         }
1774         skb->BEbits = skb->data[2];
1775         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1776
1777         /*
1778          * Do protocol ID decompression on the first fragment of each packet.
1779          */
1780         if ((skb->BEbits & B) && (skb->data[0] & 1))
1781                 *skb_push(skb, 1) = 0;
1782
1783         /*
1784          * Expand sequence number to 32 bits, making it as close
1785          * as possible to ppp->minseq.
1786          */
1787         seq |= ppp->minseq & ~mask;
1788         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1789                 seq += mask + 1;
1790         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1791                 seq -= mask + 1;        /* should never happen */
1792         skb->sequence = seq;
1793         pch->lastseq = seq;
1794
1795         /*
1796          * If this packet comes before the next one we were expecting,
1797          * drop it.
1798          */
1799         if (seq_before(seq, ppp->nextseq)) {
1800                 kfree_skb(skb);
1801                 ++ppp->stats.rx_dropped;
1802                 ppp_receive_error(ppp);
1803                 return;
1804         }
1805
1806         /*
1807          * Reevaluate minseq, the minimum over all channels of the
1808          * last sequence number received on each channel.  Because of
1809          * the increasing sequence number rule, we know that any fragment
1810          * before `minseq' which hasn't arrived is never going to arrive.
1811          * The list of channels can't change because we have the receive
1812          * side of the ppp unit locked.
1813          */
1814         list_for_each_entry(ch, &ppp->channels, clist) {
1815                 if (seq_before(ch->lastseq, seq))
1816                         seq = ch->lastseq;
1817         }
1818         if (seq_before(ppp->minseq, seq))
1819                 ppp->minseq = seq;
1820
1821         /* Put the fragment on the reconstruction queue */
1822         ppp_mp_insert(ppp, skb);
1823
1824         /* If the queue is getting long, don't wait any longer for packets
1825            before the start of the queue. */
1826         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN
1827             && seq_before(ppp->minseq, ppp->mrq.next->sequence))
1828                 ppp->minseq = ppp->mrq.next->sequence;
1829
1830         /* Pull completed packets off the queue and receive them. */
1831         while ((skb = ppp_mp_reconstruct(ppp)) != 0)
1832                 ppp_receive_nonmp_frame(ppp, skb);
1833
1834         return;
1835
1836  err:
1837         kfree_skb(skb);
1838         ppp_receive_error(ppp);
1839 }
1840
1841 /*
1842  * Insert a fragment on the MP reconstruction queue.
1843  * The queue is ordered by increasing sequence number.
1844  */
1845 static void
1846 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1847 {
1848         struct sk_buff *p;
1849         struct sk_buff_head *list = &ppp->mrq;
1850         u32 seq = skb->sequence;
1851
1852         /* N.B. we don't need to lock the list lock because we have the
1853            ppp unit receive-side lock. */
1854         for (p = list->next; p != (struct sk_buff *)list; p = p->next)
1855                 if (seq_before(seq, p->sequence))
1856                         break;
1857         __skb_insert(skb, p->prev, p, list);
1858 }
1859
1860 /*
1861  * Reconstruct a packet from the MP fragment queue.
1862  * We go through increasing sequence numbers until we find a
1863  * complete packet, or we get to the sequence number for a fragment
1864  * which hasn't arrived but might still do so.
1865  */
1866 struct sk_buff *
1867 ppp_mp_reconstruct(struct ppp *ppp)
1868 {
1869         u32 seq = ppp->nextseq;
1870         u32 minseq = ppp->minseq;
1871         struct sk_buff_head *list = &ppp->mrq;
1872         struct sk_buff *p, *next;
1873         struct sk_buff *head, *tail;
1874         struct sk_buff *skb = NULL;
1875         int lost = 0, len = 0;
1876
1877         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1878                 return NULL;
1879         head = list->next;
1880         tail = NULL;
1881         for (p = head; p != (struct sk_buff *) list; p = next) {
1882                 next = p->next;
1883                 if (seq_before(p->sequence, seq)) {
1884                         /* this can't happen, anyway ignore the skb */
1885                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1886                                p->sequence, seq);
1887                         head = next;
1888                         continue;
1889                 }
1890                 if (p->sequence != seq) {
1891                         /* Fragment `seq' is missing.  If it is after
1892                            minseq, it might arrive later, so stop here. */
1893                         if (seq_after(seq, minseq))
1894                                 break;
1895                         /* Fragment `seq' is lost, keep going. */
1896                         lost = 1;
1897                         seq = seq_before(minseq, p->sequence)?
1898                                 minseq + 1: p->sequence;
1899                         next = p;
1900                         continue;
1901                 }
1902
1903                 /*
1904                  * At this point we know that all the fragments from
1905                  * ppp->nextseq to seq are either present or lost.
1906                  * Also, there are no complete packets in the queue
1907                  * that have no missing fragments and end before this
1908                  * fragment.
1909                  */
1910
1911                 /* B bit set indicates this fragment starts a packet */
1912                 if (p->BEbits & B) {
1913                         head = p;
1914                         lost = 0;
1915                         len = 0;
1916                 }
1917
1918                 len += p->len;
1919
1920                 /* Got a complete packet yet? */
1921                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1922                         if (len > ppp->mrru + 2) {
1923                                 ++ppp->stats.rx_length_errors;
1924                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1925                                        " is too long (%d)\n", len);
1926                         } else if (p == head) {
1927                                 /* fragment is complete packet - reuse skb */
1928                                 tail = p;
1929                                 skb = skb_get(p);
1930                                 break;
1931                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1932                                 ++ppp->stats.rx_missed_errors;
1933                                 printk(KERN_DEBUG "PPP: no memory for "
1934                                        "reconstructed packet");
1935                         } else {
1936                                 tail = p;
1937                                 break;
1938                         }
1939                         ppp->nextseq = seq + 1;
1940                 }
1941
1942                 /*
1943                  * If this is the ending fragment of a packet,
1944                  * and we haven't found a complete valid packet yet,
1945                  * we can discard up to and including this fragment.
1946                  */
1947                 if (p->BEbits & E)
1948                         head = next;
1949
1950                 ++seq;
1951         }
1952
1953         /* If we have a complete packet, copy it all into one skb. */
1954         if (tail != NULL) {
1955                 /* If we have discarded any fragments,
1956                    signal a receive error. */
1957                 if (head->sequence != ppp->nextseq) {
1958                         if (ppp->debug & 1)
1959                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1960                                        ppp->nextseq, head->sequence-1);
1961                         ++ppp->stats.rx_dropped;
1962                         ppp_receive_error(ppp);
1963                 }
1964
1965                 if (head != tail)
1966                         /* copy to a single skb */
1967                         for (p = head; p != tail->next; p = p->next)
1968                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1969                 ppp->nextseq = tail->sequence + 1;
1970                 head = tail->next;
1971         }
1972
1973         /* Discard all the skbuffs that we have copied the data out of
1974            or that we can't use. */
1975         while ((p = list->next) != head) {
1976                 __skb_unlink(p, list);
1977                 kfree_skb(p);
1978         }
1979
1980         return skb;
1981 }
1982 #endif /* CONFIG_PPP_MULTILINK */
1983
1984 /*
1985  * Channel interface.
1986  */
1987
1988 /*
1989  * Create a new, unattached ppp channel.
1990  */
1991 int
1992 ppp_register_channel(struct ppp_channel *chan)
1993 {
1994         struct channel *pch;
1995
1996         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
1997         if (pch == 0)
1998                 return -ENOMEM;
1999         pch->ppp = NULL;
2000         pch->chan = chan;
2001         chan->ppp = pch;
2002         init_ppp_file(&pch->file, CHANNEL);
2003         pch->file.hdrlen = chan->hdrlen;
2004 #ifdef CONFIG_PPP_MULTILINK
2005         pch->lastseq = -1;
2006 #endif /* CONFIG_PPP_MULTILINK */
2007         init_rwsem(&pch->chan_sem);
2008         spin_lock_init(&pch->downl);
2009         rwlock_init(&pch->upl);
2010         spin_lock_bh(&all_channels_lock);
2011         pch->file.index = ++last_channel_index;
2012         list_add(&pch->list, &new_channels);
2013         atomic_inc(&channel_count);
2014         spin_unlock_bh(&all_channels_lock);
2015         return 0;
2016 }
2017
2018 /*
2019  * Return the index of a channel.
2020  */
2021 int ppp_channel_index(struct ppp_channel *chan)
2022 {
2023         struct channel *pch = chan->ppp;
2024
2025         if (pch != 0)
2026                 return pch->file.index;
2027         return -1;
2028 }
2029
2030 /*
2031  * Return the PPP unit number to which a channel is connected.
2032  */
2033 int ppp_unit_number(struct ppp_channel *chan)
2034 {
2035         struct channel *pch = chan->ppp;
2036         int unit = -1;
2037
2038         if (pch != 0) {
2039                 read_lock_bh(&pch->upl);
2040                 if (pch->ppp != 0)
2041                         unit = pch->ppp->file.index;
2042                 read_unlock_bh(&pch->upl);
2043         }
2044         return unit;
2045 }
2046
2047 /*
2048  * Disconnect a channel from the generic layer.
2049  * This must be called in process context.
2050  */
2051 void
2052 ppp_unregister_channel(struct ppp_channel *chan)
2053 {
2054         struct channel *pch = chan->ppp;
2055
2056         if (pch == 0)
2057                 return;         /* should never happen */
2058         chan->ppp = NULL;
2059
2060         /*
2061          * This ensures that we have returned from any calls into the
2062          * the channel's start_xmit or ioctl routine before we proceed.
2063          */
2064         down_write(&pch->chan_sem);
2065         spin_lock_bh(&pch->downl);
2066         pch->chan = NULL;
2067         spin_unlock_bh(&pch->downl);
2068         up_write(&pch->chan_sem);
2069         ppp_disconnect_channel(pch);
2070         spin_lock_bh(&all_channels_lock);
2071         list_del(&pch->list);
2072         spin_unlock_bh(&all_channels_lock);
2073         pch->file.dead = 1;
2074         wake_up_interruptible(&pch->file.rwait);
2075         if (atomic_dec_and_test(&pch->file.refcnt))
2076                 ppp_destroy_channel(pch);
2077 }
2078
2079 /*
2080  * Callback from a channel when it can accept more to transmit.
2081  * This should be called at BH/softirq level, not interrupt level.
2082  */
2083 void
2084 ppp_output_wakeup(struct ppp_channel *chan)
2085 {
2086         struct channel *pch = chan->ppp;
2087
2088         if (pch == 0)
2089                 return;
2090         ppp_channel_push(pch);
2091 }
2092
2093 /*
2094  * Compression control.
2095  */
2096
2097 /* Process the PPPIOCSCOMPRESS ioctl. */
2098 static int
2099 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2100 {
2101         int err;
2102         struct compressor *cp, *ocomp;
2103         struct ppp_option_data data;
2104         void *state, *ostate;
2105         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2106
2107         err = -EFAULT;
2108         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2109             || (data.length <= CCP_MAX_OPTION_LENGTH
2110                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2111                 goto out;
2112         err = -EINVAL;
2113         if (data.length > CCP_MAX_OPTION_LENGTH
2114             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2115                 goto out;
2116
2117         cp = find_compressor(ccp_option[0]);
2118 #ifdef CONFIG_KMOD
2119         if (cp == 0) {
2120                 request_module("ppp-compress-%d", ccp_option[0]);
2121                 cp = find_compressor(ccp_option[0]);
2122         }
2123 #endif /* CONFIG_KMOD */
2124         if (cp == 0)
2125                 goto out;
2126
2127         err = -ENOBUFS;
2128         if (data.transmit) {
2129                 state = cp->comp_alloc(ccp_option, data.length);
2130                 if (state != 0) {
2131                         ppp_xmit_lock(ppp);
2132                         ppp->xstate &= ~SC_COMP_RUN;
2133                         ocomp = ppp->xcomp;
2134                         ostate = ppp->xc_state;
2135                         ppp->xcomp = cp;
2136                         ppp->xc_state = state;
2137                         ppp_xmit_unlock(ppp);
2138                         if (ostate != 0) {
2139                                 ocomp->comp_free(ostate);
2140                                 module_put(ocomp->owner);
2141                         }
2142                         err = 0;
2143                 } else
2144                         module_put(cp->owner);
2145
2146         } else {
2147                 state = cp->decomp_alloc(ccp_option, data.length);
2148                 if (state != 0) {
2149                         ppp_recv_lock(ppp);
2150                         ppp->rstate &= ~SC_DECOMP_RUN;
2151                         ocomp = ppp->rcomp;
2152                         ostate = ppp->rc_state;
2153                         ppp->rcomp = cp;
2154                         ppp->rc_state = state;
2155                         ppp_recv_unlock(ppp);
2156                         if (ostate != 0) {
2157                                 ocomp->decomp_free(ostate);
2158                                 module_put(ocomp->owner);
2159                         }
2160                         err = 0;
2161                 } else
2162                         module_put(cp->owner);
2163         }
2164
2165  out:
2166         return err;
2167 }
2168
2169 /*
2170  * Look at a CCP packet and update our state accordingly.
2171  * We assume the caller has the xmit or recv path locked.
2172  */
2173 static void
2174 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2175 {
2176         unsigned char *dp;
2177         int len;
2178
2179         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2180                 return; /* no header */
2181         dp = skb->data + 2;
2182
2183         switch (CCP_CODE(dp)) {
2184         case CCP_CONFREQ:
2185
2186                 /* A ConfReq starts negotiation of compression
2187                  * in one direction of transmission,
2188                  * and hence brings it down...but which way?
2189                  *
2190                  * Remember:
2191                  * A ConfReq indicates what the sender would like to receive
2192                  */
2193                 if(inbound)
2194                         /* He is proposing what I should send */
2195                         ppp->xstate &= ~SC_COMP_RUN;
2196                 else
2197                         /* I am proposing to what he should send */
2198                         ppp->rstate &= ~SC_DECOMP_RUN;
2199
2200                 break;
2201
2202         case CCP_TERMREQ:
2203         case CCP_TERMACK:
2204                 /*
2205                  * CCP is going down, both directions of transmission
2206                  */
2207                 ppp->rstate &= ~SC_DECOMP_RUN;
2208                 ppp->xstate &= ~SC_COMP_RUN;
2209                 break;
2210
2211         case CCP_CONFACK:
2212                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2213                         break;
2214                 len = CCP_LENGTH(dp);
2215                 if (!pskb_may_pull(skb, len + 2))
2216                         return;         /* too short */
2217                 dp += CCP_HDRLEN;
2218                 len -= CCP_HDRLEN;
2219                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2220                         break;
2221                 if (inbound) {
2222                         /* we will start receiving compressed packets */
2223                         if (ppp->rc_state == 0)
2224                                 break;
2225                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2226                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2227                                 ppp->rstate |= SC_DECOMP_RUN;
2228                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2229                         }
2230                 } else {
2231                         /* we will soon start sending compressed packets */
2232                         if (ppp->xc_state == 0)
2233                                 break;
2234                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2235                                         ppp->file.index, 0, ppp->debug))
2236                                 ppp->xstate |= SC_COMP_RUN;
2237                 }
2238                 break;
2239
2240         case CCP_RESETACK:
2241                 /* reset the [de]compressor */
2242                 if ((ppp->flags & SC_CCP_UP) == 0)
2243                         break;
2244                 if (inbound) {
2245                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2246                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2247                                 ppp->rstate &= ~SC_DC_ERROR;
2248                         }
2249                 } else {
2250                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2251                                 ppp->xcomp->comp_reset(ppp->xc_state);
2252                 }
2253                 break;
2254         }
2255 }
2256
2257 /* Free up compression resources. */
2258 static void
2259 ppp_ccp_closed(struct ppp *ppp)
2260 {
2261         void *xstate, *rstate;
2262         struct compressor *xcomp, *rcomp;
2263
2264         ppp_lock(ppp);
2265         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2266         ppp->xstate = 0;
2267         xcomp = ppp->xcomp;
2268         xstate = ppp->xc_state;
2269         ppp->xc_state = NULL;
2270         ppp->rstate = 0;
2271         rcomp = ppp->rcomp;
2272         rstate = ppp->rc_state;
2273         ppp->rc_state = NULL;
2274         ppp_unlock(ppp);
2275
2276         if (xstate) {
2277                 xcomp->comp_free(xstate);
2278                 module_put(xcomp->owner);
2279         }
2280         if (rstate) {
2281                 rcomp->decomp_free(rstate);
2282                 module_put(rcomp->owner);
2283         }
2284 }
2285
2286 /* List of compressors. */
2287 static LIST_HEAD(compressor_list);
2288 static DEFINE_SPINLOCK(compressor_list_lock);
2289
2290 struct compressor_entry {
2291         struct list_head list;
2292         struct compressor *comp;
2293 };
2294
2295 static struct compressor_entry *
2296 find_comp_entry(int proto)
2297 {
2298         struct compressor_entry *ce;
2299
2300         list_for_each_entry(ce, &compressor_list, list) {
2301                 if (ce->comp->compress_proto == proto)
2302                         return ce;
2303         }
2304         return NULL;
2305 }
2306
2307 /* Register a compressor */
2308 int
2309 ppp_register_compressor(struct compressor *cp)
2310 {
2311         struct compressor_entry *ce;
2312         int ret;
2313         spin_lock(&compressor_list_lock);
2314         ret = -EEXIST;
2315         if (find_comp_entry(cp->compress_proto) != 0)
2316                 goto out;
2317         ret = -ENOMEM;
2318         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2319         if (ce == 0)
2320                 goto out;
2321         ret = 0;
2322         ce->comp = cp;
2323         list_add(&ce->list, &compressor_list);
2324  out:
2325         spin_unlock(&compressor_list_lock);
2326         return ret;
2327 }
2328
2329 /* Unregister a compressor */
2330 void
2331 ppp_unregister_compressor(struct compressor *cp)
2332 {
2333         struct compressor_entry *ce;
2334
2335         spin_lock(&compressor_list_lock);
2336         ce = find_comp_entry(cp->compress_proto);
2337         if (ce != 0 && ce->comp == cp) {
2338                 list_del(&ce->list);
2339                 kfree(ce);
2340         }
2341         spin_unlock(&compressor_list_lock);
2342 }
2343
2344 /* Find a compressor. */
2345 static struct compressor *
2346 find_compressor(int type)
2347 {
2348         struct compressor_entry *ce;
2349         struct compressor *cp = NULL;
2350
2351         spin_lock(&compressor_list_lock);
2352         ce = find_comp_entry(type);
2353         if (ce != 0) {
2354                 cp = ce->comp;
2355                 if (!try_module_get(cp->owner))
2356                         cp = NULL;
2357         }
2358         spin_unlock(&compressor_list_lock);
2359         return cp;
2360 }
2361
2362 /*
2363  * Miscelleneous stuff.
2364  */
2365
2366 static void
2367 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2368 {
2369         struct slcompress *vj = ppp->vj;
2370
2371         memset(st, 0, sizeof(*st));
2372         st->p.ppp_ipackets = ppp->stats.rx_packets;
2373         st->p.ppp_ierrors = ppp->stats.rx_errors;
2374         st->p.ppp_ibytes = ppp->stats.rx_bytes;
2375         st->p.ppp_opackets = ppp->stats.tx_packets;
2376         st->p.ppp_oerrors = ppp->stats.tx_errors;
2377         st->p.ppp_obytes = ppp->stats.tx_bytes;
2378         if (vj == 0)
2379                 return;
2380         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2381         st->vj.vjs_compressed = vj->sls_o_compressed;
2382         st->vj.vjs_searches = vj->sls_o_searches;
2383         st->vj.vjs_misses = vj->sls_o_misses;
2384         st->vj.vjs_errorin = vj->sls_i_error;
2385         st->vj.vjs_tossed = vj->sls_i_tossed;
2386         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2387         st->vj.vjs_compressedin = vj->sls_i_compressed;
2388 }
2389
2390 /*
2391  * Stuff for handling the lists of ppp units and channels
2392  * and for initialization.
2393  */
2394
2395 /*
2396  * Create a new ppp interface unit.  Fails if it can't allocate memory
2397  * or if there is already a unit with the requested number.
2398  * unit == -1 means allocate a new number.
2399  */
2400 static struct ppp *
2401 ppp_create_interface(int unit, int *retp)
2402 {
2403         struct ppp *ppp;
2404         struct net_device *dev = NULL;
2405         int ret = -ENOMEM;
2406         int i;
2407
2408         ppp = kzalloc(sizeof(struct ppp), GFP_KERNEL);
2409         if (!ppp)
2410                 goto out;
2411         dev = alloc_netdev(0, "", ppp_setup);
2412         if (!dev)
2413                 goto out1;
2414
2415         ppp->mru = PPP_MRU;
2416         init_ppp_file(&ppp->file, INTERFACE);
2417         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2418         for (i = 0; i < NUM_NP; ++i)
2419                 ppp->npmode[i] = NPMODE_PASS;
2420         INIT_LIST_HEAD(&ppp->channels);
2421         spin_lock_init(&ppp->rlock);
2422         spin_lock_init(&ppp->wlock);
2423 #ifdef CONFIG_PPP_MULTILINK
2424         ppp->minseq = -1;
2425         skb_queue_head_init(&ppp->mrq);
2426 #endif /* CONFIG_PPP_MULTILINK */
2427         ppp->dev = dev;
2428         dev->priv = ppp;
2429
2430         dev->hard_start_xmit = ppp_start_xmit;
2431         dev->get_stats = ppp_net_stats;
2432         dev->do_ioctl = ppp_net_ioctl;
2433
2434         ret = -EEXIST;
2435         mutex_lock(&all_ppp_mutex);
2436         if (unit < 0)
2437                 unit = cardmap_find_first_free(all_ppp_units);
2438         else if (cardmap_get(all_ppp_units, unit) != NULL)
2439                 goto out2;      /* unit already exists */
2440
2441         /* Initialize the new ppp unit */
2442         ppp->file.index = unit;
2443         sprintf(dev->name, "ppp%d", unit);
2444
2445         ret = register_netdev(dev);
2446         if (ret != 0) {
2447                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2448                        dev->name, ret);
2449                 goto out2;
2450         }
2451
2452         atomic_inc(&ppp_unit_count);
2453         ret = cardmap_set(&all_ppp_units, unit, ppp);
2454         if (ret != 0)
2455                 goto out3;
2456
2457         mutex_unlock(&all_ppp_mutex);
2458         *retp = 0;
2459         return ppp;
2460
2461 out3:
2462         atomic_dec(&ppp_unit_count);
2463 out2:
2464         mutex_unlock(&all_ppp_mutex);
2465         free_netdev(dev);
2466 out1:
2467         kfree(ppp);
2468 out:
2469         *retp = ret;
2470         return NULL;
2471 }
2472
2473 /*
2474  * Initialize a ppp_file structure.
2475  */
2476 static void
2477 init_ppp_file(struct ppp_file *pf, int kind)
2478 {
2479         pf->kind = kind;
2480         skb_queue_head_init(&pf->xq);
2481         skb_queue_head_init(&pf->rq);
2482         atomic_set(&pf->refcnt, 1);
2483         init_waitqueue_head(&pf->rwait);
2484 }
2485
2486 /*
2487  * Take down a ppp interface unit - called when the owning file
2488  * (the one that created the unit) is closed or detached.
2489  */
2490 static void ppp_shutdown_interface(struct ppp *ppp)
2491 {
2492         struct net_device *dev;
2493
2494         mutex_lock(&all_ppp_mutex);
2495         ppp_lock(ppp);
2496         dev = ppp->dev;
2497         ppp->dev = NULL;
2498         ppp_unlock(ppp);
2499         /* This will call dev_close() for us. */
2500         if (dev) {
2501                 unregister_netdev(dev);
2502                 free_netdev(dev);
2503         }
2504         cardmap_set(&all_ppp_units, ppp->file.index, NULL);
2505         ppp->file.dead = 1;
2506         ppp->owner = NULL;
2507         wake_up_interruptible(&ppp->file.rwait);
2508         mutex_unlock(&all_ppp_mutex);
2509 }
2510
2511 /*
2512  * Free the memory used by a ppp unit.  This is only called once
2513  * there are no channels connected to the unit and no file structs
2514  * that reference the unit.
2515  */
2516 static void ppp_destroy_interface(struct ppp *ppp)
2517 {
2518         atomic_dec(&ppp_unit_count);
2519
2520         if (!ppp->file.dead || ppp->n_channels) {
2521                 /* "can't happen" */
2522                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2523                        "n_channels=%d !\n", ppp, ppp->file.dead,
2524                        ppp->n_channels);
2525                 return;
2526         }
2527
2528         ppp_ccp_closed(ppp);
2529         if (ppp->vj) {
2530                 slhc_free(ppp->vj);
2531                 ppp->vj = NULL;
2532         }
2533         skb_queue_purge(&ppp->file.xq);
2534         skb_queue_purge(&ppp->file.rq);
2535 #ifdef CONFIG_PPP_MULTILINK
2536         skb_queue_purge(&ppp->mrq);
2537 #endif /* CONFIG_PPP_MULTILINK */
2538 #ifdef CONFIG_PPP_FILTER
2539         kfree(ppp->pass_filter);
2540         ppp->pass_filter = NULL;
2541         kfree(ppp->active_filter);
2542         ppp->active_filter = NULL;
2543 #endif /* CONFIG_PPP_FILTER */
2544
2545         if (ppp->xmit_pending)
2546                 kfree_skb(ppp->xmit_pending);
2547
2548         kfree(ppp);
2549 }
2550
2551 /*
2552  * Locate an existing ppp unit.
2553  * The caller should have locked the all_ppp_mutex.
2554  */
2555 static struct ppp *
2556 ppp_find_unit(int unit)
2557 {
2558         return cardmap_get(all_ppp_units, unit);
2559 }
2560
2561 /*
2562  * Locate an existing ppp channel.
2563  * The caller should have locked the all_channels_lock.
2564  * First we look in the new_channels list, then in the
2565  * all_channels list.  If found in the new_channels list,
2566  * we move it to the all_channels list.  This is for speed
2567  * when we have a lot of channels in use.
2568  */
2569 static struct channel *
2570 ppp_find_channel(int unit)
2571 {
2572         struct channel *pch;
2573
2574         list_for_each_entry(pch, &new_channels, list) {
2575                 if (pch->file.index == unit) {
2576                         list_move(&pch->list, &all_channels);
2577                         return pch;
2578                 }
2579         }
2580         list_for_each_entry(pch, &all_channels, list) {
2581                 if (pch->file.index == unit)
2582                         return pch;
2583         }
2584         return NULL;
2585 }
2586
2587 /*
2588  * Connect a PPP channel to a PPP interface unit.
2589  */
2590 static int
2591 ppp_connect_channel(struct channel *pch, int unit)
2592 {
2593         struct ppp *ppp;
2594         int ret = -ENXIO;
2595         int hdrlen;
2596
2597         mutex_lock(&all_ppp_mutex);
2598         ppp = ppp_find_unit(unit);
2599         if (ppp == 0)
2600                 goto out;
2601         write_lock_bh(&pch->upl);
2602         ret = -EINVAL;
2603         if (pch->ppp != 0)
2604                 goto outl;
2605
2606         ppp_lock(ppp);
2607         if (pch->file.hdrlen > ppp->file.hdrlen)
2608                 ppp->file.hdrlen = pch->file.hdrlen;
2609         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2610         if (ppp->dev && hdrlen > ppp->dev->hard_header_len)
2611                 ppp->dev->hard_header_len = hdrlen;
2612         list_add_tail(&pch->clist, &ppp->channels);
2613         ++ppp->n_channels;
2614         pch->ppp = ppp;
2615         atomic_inc(&ppp->file.refcnt);
2616         ppp_unlock(ppp);
2617         ret = 0;
2618
2619  outl:
2620         write_unlock_bh(&pch->upl);
2621  out:
2622         mutex_unlock(&all_ppp_mutex);
2623         return ret;
2624 }
2625
2626 /*
2627  * Disconnect a channel from its ppp unit.
2628  */
2629 static int
2630 ppp_disconnect_channel(struct channel *pch)
2631 {
2632         struct ppp *ppp;
2633         int err = -EINVAL;
2634
2635         write_lock_bh(&pch->upl);
2636         ppp = pch->ppp;
2637         pch->ppp = NULL;
2638         write_unlock_bh(&pch->upl);
2639         if (ppp != 0) {
2640                 /* remove it from the ppp unit's list */
2641                 ppp_lock(ppp);
2642                 list_del(&pch->clist);
2643                 if (--ppp->n_channels == 0)
2644                         wake_up_interruptible(&ppp->file.rwait);
2645                 ppp_unlock(ppp);
2646                 if (atomic_dec_and_test(&ppp->file.refcnt))
2647                         ppp_destroy_interface(ppp);
2648                 err = 0;
2649         }
2650         return err;
2651 }
2652
2653 /*
2654  * Free up the resources used by a ppp channel.
2655  */
2656 static void ppp_destroy_channel(struct channel *pch)
2657 {
2658         atomic_dec(&channel_count);
2659
2660         if (!pch->file.dead) {
2661                 /* "can't happen" */
2662                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2663                        pch);
2664                 return;
2665         }
2666         skb_queue_purge(&pch->file.xq);
2667         skb_queue_purge(&pch->file.rq);
2668         kfree(pch);
2669 }
2670
2671 static void __exit ppp_cleanup(void)
2672 {
2673         /* should never happen */
2674         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2675                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2676         cardmap_destroy(&all_ppp_units);
2677         if (unregister_chrdev(PPP_MAJOR, "ppp") != 0)
2678                 printk(KERN_ERR "PPP: failed to unregister PPP device\n");
2679         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2680         class_destroy(ppp_class);
2681 }
2682
2683 /*
2684  * Cardmap implementation.
2685  */
2686 static void *cardmap_get(struct cardmap *map, unsigned int nr)
2687 {
2688         struct cardmap *p;
2689         int i;
2690
2691         for (p = map; p != NULL; ) {
2692                 if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
2693                         return NULL;
2694                 if (p->shift == 0)
2695                         return p->ptr[i];
2696                 nr &= ~(CARDMAP_MASK << p->shift);
2697                 p = p->ptr[i];
2698         }
2699         return NULL;
2700 }
2701
2702 static int cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
2703 {
2704         struct cardmap *p;
2705         int i;
2706
2707         p = *pmap;
2708         if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
2709                 do {
2710                         /* need a new top level */
2711                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2712                         if (!np)
2713                                 goto enomem;
2714                         np->ptr[0] = p;
2715                         if (p != NULL) {
2716                                 np->shift = p->shift + CARDMAP_ORDER;
2717                                 p->parent = np;
2718                         } else
2719                                 np->shift = 0;
2720                         p = np;
2721                 } while ((nr >> p->shift) >= CARDMAP_WIDTH);
2722                 *pmap = p;
2723         }
2724         while (p->shift > 0) {
2725                 i = (nr >> p->shift) & CARDMAP_MASK;
2726                 if (p->ptr[i] == NULL) {
2727                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2728                         if (!np)
2729                                 goto enomem;
2730                         np->shift = p->shift - CARDMAP_ORDER;
2731                         np->parent = p;
2732                         p->ptr[i] = np;
2733                 }
2734                 if (ptr == NULL)
2735                         clear_bit(i, &p->inuse);
2736                 p = p->ptr[i];
2737         }
2738         i = nr & CARDMAP_MASK;
2739         p->ptr[i] = ptr;
2740         if (ptr != NULL)
2741                 set_bit(i, &p->inuse);
2742         else
2743                 clear_bit(i, &p->inuse);
2744         return 0;
2745  enomem:
2746         return -ENOMEM;
2747 }
2748
2749 static unsigned int cardmap_find_first_free(struct cardmap *map)
2750 {
2751         struct cardmap *p;
2752         unsigned int nr = 0;
2753         int i;
2754
2755         if ((p = map) == NULL)
2756                 return 0;
2757         for (;;) {
2758                 i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
2759                 if (i >= CARDMAP_WIDTH) {
2760                         if (p->parent == NULL)
2761                                 return CARDMAP_WIDTH << p->shift;
2762                         p = p->parent;
2763                         i = (nr >> p->shift) & CARDMAP_MASK;
2764                         set_bit(i, &p->inuse);
2765                         continue;
2766                 }
2767                 nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
2768                 if (p->shift == 0 || p->ptr[i] == NULL)
2769                         return nr;
2770                 p = p->ptr[i];
2771         }
2772 }
2773
2774 static void cardmap_destroy(struct cardmap **pmap)
2775 {
2776         struct cardmap *p, *np;
2777         int i;
2778
2779         for (p = *pmap; p != NULL; p = np) {
2780                 if (p->shift != 0) {
2781                         for (i = 0; i < CARDMAP_WIDTH; ++i)
2782                                 if (p->ptr[i] != NULL)
2783                                         break;
2784                         if (i < CARDMAP_WIDTH) {
2785                                 np = p->ptr[i];
2786                                 p->ptr[i] = NULL;
2787                                 continue;
2788                         }
2789                 }
2790                 np = p->parent;
2791                 kfree(p);
2792         }
2793         *pmap = NULL;
2794 }
2795
2796 /* Module/initialization stuff */
2797
2798 module_init(ppp_init);
2799 module_exit(ppp_cleanup);
2800
2801 EXPORT_SYMBOL(ppp_register_channel);
2802 EXPORT_SYMBOL(ppp_unregister_channel);
2803 EXPORT_SYMBOL(ppp_channel_index);
2804 EXPORT_SYMBOL(ppp_unit_number);
2805 EXPORT_SYMBOL(ppp_input);
2806 EXPORT_SYMBOL(ppp_input_error);
2807 EXPORT_SYMBOL(ppp_output_wakeup);
2808 EXPORT_SYMBOL(ppp_register_compressor);
2809 EXPORT_SYMBOL(ppp_unregister_compressor);
2810 MODULE_LICENSE("GPL");
2811 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2812 MODULE_ALIAS("/dev/ppp");