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/smp_lock.h>
  43 #include <linux/spinlock.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 #ifdef CONFIG_PPP_FILTER
 128         struct sock_filter *pass_filter;        /* filter for packets to pass */
 129         struct sock_filter *active_filter;/* filter for pkts to reset idle */
 130         unsigned pass_len, active_len;
 131 #endif /* CONFIG_PPP_FILTER */
 132 };
 133
 134 /*
 135  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
 136  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
 137  * SC_MUST_COMP
 138  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
 139  * Bits in xstate: SC_COMP_RUN
 140  */
 141 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
 142                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
 143                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
 144
 145 /*
 146  * Private data structure for each channel.
 147  * This includes the data structure used for multilink.
 148  */
 149 struct channel {
 150         struct ppp_file file;           /* stuff for read/write/poll */
 151         struct list_head list;          /* link in all/new_channels list */
 152         struct ppp_channel *chan;       /* public channel data structure */
 153         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
 154         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
 155         struct ppp      *ppp;           /* ppp unit we're connected to */
 156         struct list_head clist;         /* link in list of channels per unit */
 157         rwlock_t        upl;            /* protects `ppp' */
 158 #ifdef CONFIG_PPP_MULTILINK
 159         u8              avail;          /* flag used in multilink stuff */
 160         u8              had_frag;       /* >= 1 fragments have been sent */
 161         u32             lastseq;        /* MP: last sequence # received */
 162 #endif /* CONFIG_PPP_MULTILINK */
 163 };
 164
 165 /*
 166  * SMP locking issues:
 167  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
 168  * list and the ppp.n_channels field, you need to take both locks
 169  * before you modify them.
 170  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
 171  * channel.downl.
 172  */
 173
 174 /*
 175  * A cardmap represents a mapping from unsigned integers to pointers,
 176  * and provides a fast "find lowest unused number" operation.
 177  * It uses a broad (32-way) tree with a bitmap at each level.
 178  * It is designed to be space-efficient for small numbers of entries
 179  * and time-efficient for large numbers of entries.
 180  */
 181 #define CARDMAP_ORDER   5
 182 #define CARDMAP_WIDTH   (1U << CARDMAP_ORDER)
 183 #define CARDMAP_MASK    (CARDMAP_WIDTH - 1)
 184
 185 struct cardmap {
 186         int shift;
 187         unsigned long inuse;
 188         struct cardmap *parent;
 189         void *ptr[CARDMAP_WIDTH];
 190 };
 191 static void *cardmap_get(struct cardmap *map, unsigned int nr);
 192 static int cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
 193 static unsigned int cardmap_find_first_free(struct cardmap *map);
 194 static void cardmap_destroy(struct cardmap **map);
 195
 196 /*
 197  * all_ppp_mutex protects the all_ppp_units mapping.
 198  * It also ensures that finding a ppp unit in the all_ppp_units map
 199  * and updating its file.refcnt field is atomic.
 200  */
 201 static DEFINE_MUTEX(all_ppp_mutex);
 202 static struct cardmap *all_ppp_units;
 203 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 204
 205 /*
 206  * all_channels_lock protects all_channels and last_channel_index,
 207  * and the atomicity of find a channel and updating its file.refcnt
 208  * field.
 209  */
 210 static DEFINE_SPINLOCK(all_channels_lock);
 211 static LIST_HEAD(all_channels);
 212 static LIST_HEAD(new_channels);
 213 static int last_channel_index;
 214 static atomic_t channel_count = ATOMIC_INIT(0);
 215
 216 /* Get the PPP protocol number from a skb */
 217 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
 218
 219 /* We limit the length of ppp->file.rq to this (arbitrary) value */
 220 #define PPP_MAX_RQLEN   32
 221
 222 /*
 223  * Maximum number of multilink fragments queued up.
 224  * This has to be large enough to cope with the maximum latency of
 225  * the slowest channel relative to the others.  Strictly it should
 226  * depend on the number of channels and their characteristics.
 227  */
 228 #define PPP_MP_MAX_QLEN 128
 229
 230 /* Multilink header bits. */
 231 #define B       0x80            /* this fragment begins a packet */
 232 #define E       0x40            /* this fragment ends a packet */
 233
 234 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
 235 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
 236 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
 237
 238 /* Prototypes. */
 239 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 240                                 unsigned int cmd, unsigned long arg);
 241 static void ppp_xmit_process(struct ppp *ppp);
 242 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
 243 static void ppp_push(struct ppp *ppp);
 244 static void ppp_channel_push(struct channel *pch);
 245 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
 246                               struct channel *pch);
 247 static void ppp_receive_error(struct ppp *ppp);
 248 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
 249 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
 250                                             struct sk_buff *skb);
 251 #ifdef CONFIG_PPP_MULTILINK
 252 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
 253                                 struct channel *pch);
 254 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
 255 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
 256 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
 257 #endif /* CONFIG_PPP_MULTILINK */
 258 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
 259 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
 260 static void ppp_ccp_closed(struct ppp *ppp);
 261 static struct compressor *find_compressor(int type);
 262 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
 263 static struct ppp *ppp_create_interface(int unit, int *retp);
 264 static void init_ppp_file(struct ppp_file *pf, int kind);
 265 static void ppp_shutdown_interface(struct ppp *ppp);
 266 static void ppp_destroy_interface(struct ppp *ppp);
 267 static struct ppp *ppp_find_unit(int unit);
 268 static struct channel *ppp_find_channel(int unit);
 269 static int ppp_connect_channel(struct channel *pch, int unit);
 270 static int ppp_disconnect_channel(struct channel *pch);
 271 static void ppp_destroy_channel(struct channel *pch);
 272
 273 static struct class *ppp_class;
 274
 275 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
 276 static inline int proto_to_npindex(int proto)
 277 {
 278         switch (proto) {
 279         case PPP_IP:
 280                 return NP_IP;
 281         case PPP_IPV6:
 282                 return NP_IPV6;
 283         case PPP_IPX:
 284                 return NP_IPX;
 285         case PPP_AT:
 286                 return NP_AT;
 287         case PPP_MPLS_UC:
 288                 return NP_MPLS_UC;
 289         case PPP_MPLS_MC:
 290                 return NP_MPLS_MC;
 291         }
 292         return -EINVAL;
 293 }
 294
 295 /* Translates an NP index into a PPP protocol number */
 296 static const int npindex_to_proto[NUM_NP] = {
 297         PPP_IP,
 298         PPP_IPV6,
 299         PPP_IPX,
 300         PPP_AT,
 301         PPP_MPLS_UC,
 302         PPP_MPLS_MC,
 303 };
 304
 305 /* Translates an ethertype into an NP index */
 306 static inline int ethertype_to_npindex(int ethertype)
 307 {
 308         switch (ethertype) {
 309         case ETH_P_IP:
 310                 return NP_IP;
 311         case ETH_P_IPV6:
 312                 return NP_IPV6;
 313         case ETH_P_IPX:
 314                 return NP_IPX;
 315         case ETH_P_PPPTALK:
 316         case ETH_P_ATALK:
 317                 return NP_AT;
 318         case ETH_P_MPLS_UC:
 319                 return NP_MPLS_UC;
 320         case ETH_P_MPLS_MC:
 321                 return NP_MPLS_MC;
 322         }
 323         return -1;
 324 }
 325
 326 /* Translates an NP index into an ethertype */
 327 static const int npindex_to_ethertype[NUM_NP] = {
 328         ETH_P_IP,
 329         ETH_P_IPV6,
 330         ETH_P_IPX,
 331         ETH_P_PPPTALK,
 332         ETH_P_MPLS_UC,
 333         ETH_P_MPLS_MC,
 334 };
 335
 336 /*
 337  * Locking shorthand.
 338  */
 339 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
 340 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
 341 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
 342 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
 343 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
 344                                      ppp_recv_lock(ppp); } while (0)
 345 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
 346                                      ppp_xmit_unlock(ppp); } while (0)
 347
 348 /*
 349  * /dev/ppp device routines.
 350  * The /dev/ppp device is used by pppd to control the ppp unit.
 351  * It supports the read, write, ioctl and poll functions.
 352  * Open instances of /dev/ppp can be in one of three states:
 353  * unattached, attached to a ppp unit, or attached to a ppp channel.
 354  */
 355 static int ppp_open(struct inode *inode, struct file *file)
 356 {
 357         cycle_kernel_lock();
 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 *unused, struct file *file)
 367 {
 368         struct ppp_file *pf = file->private_data;
 369         struct ppp *ppp;
 370
 371         if (pf) {
 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)
 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)
 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)
 460                 return -ENXIO;
 461         ret = -ENOMEM;
 462         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
 463         if (!skb)
 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)
 496                 return 0;
 497         poll_wait(file, &pf->rwait, wait);
 498         mask = POLLOUT | POLLWRNORM;
 499         if (skb_peek(&pf->rq))
 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 long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 551 {
 552         struct ppp_file *pf = file->private_data;
 553         struct ppp *ppp;
 554         int err = -EFAULT, val, val2, i;
 555         struct ppp_idle idle;
 556         struct npioctl npi;
 557         int unit, cflags;
 558         struct slcompress *vj;
 559         void __user *argp = (void __user *)arg;
 560         int __user *p = argp;
 561
 562         if (!pf)
 563                 return ppp_unattached_ioctl(pf, file, cmd, arg);
 564
 565         if (cmd == PPPIOCDETACH) {
 566                 /*
 567                  * We have to be careful here... if the file descriptor
 568                  * has been dup'd, we could have another process in the
 569                  * middle of a poll using the same file *, so we had
 570                  * better not free the interface data structures -
 571                  * instead we fail the ioctl.  Even in this case, we
 572                  * shut down the interface if we are the owner of it.
 573                  * Actually, we should get rid of PPPIOCDETACH, userland
 574                  * (i.e. pppd) could achieve the same effect by closing
 575                  * this fd and reopening /dev/ppp.
 576                  */
 577                 err = -EINVAL;
 578                 lock_kernel();
 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_long_read(&file->f_count) <= 2) {
 585                         ppp_release(NULL, file);
 586                         err = 0;
 587                 } else
 588                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%ld\n",
 589                                atomic_long_read(&file->f_count));
 590                 unlock_kernel();
 591                 return err;
 592         }
 593
 594         if (pf->kind == CHANNEL) {
 595                 struct channel *pch;
 596                 struct ppp_channel *chan;
 597
 598                 lock_kernel();
 599                 pch = PF_TO_CHANNEL(pf);
 600
 601                 switch (cmd) {
 602                 case PPPIOCCONNECT:
 603                         if (get_user(unit, p))
 604                                 break;
 605                         err = ppp_connect_channel(pch, unit);
 606                         break;
 607
 608                 case PPPIOCDISCONN:
 609                         err = ppp_disconnect_channel(pch);
 610                         break;
 611
 612                 default:
 613                         down_read(&pch->chan_sem);
 614                         chan = pch->chan;
 615                         err = -ENOTTY;
 616                         if (chan && chan->ops->ioctl)
 617                                 err = chan->ops->ioctl(chan, cmd, arg);
 618                         up_read(&pch->chan_sem);
 619                 }
 620                 unlock_kernel();
 621                 return err;
 622         }
 623
 624         if (pf->kind != INTERFACE) {
 625                 /* can't happen */
 626                 printk(KERN_ERR "PPP: not interface or channel??\n");
 627                 return -EINVAL;
 628         }
 629
 630         lock_kernel();
 631         ppp = PF_TO_PPP(pf);
 632         switch (cmd) {
 633         case PPPIOCSMRU:
 634                 if (get_user(val, p))
 635                         break;
 636                 ppp->mru = val;
 637                 err = 0;
 638                 break;
 639
 640         case PPPIOCSFLAGS:
 641                 if (get_user(val, p))
 642                         break;
 643                 ppp_lock(ppp);
 644                 cflags = ppp->flags & ~val;
 645                 ppp->flags = val & SC_FLAG_BITS;
 646                 ppp_unlock(ppp);
 647                 if (cflags & SC_CCP_OPEN)
 648                         ppp_ccp_closed(ppp);
 649                 err = 0;
 650                 break;
 651
 652         case PPPIOCGFLAGS:
 653                 val = ppp->flags | ppp->xstate | ppp->rstate;
 654                 if (put_user(val, p))
 655                         break;
 656                 err = 0;
 657                 break;
 658
 659         case PPPIOCSCOMPRESS:
 660                 err = ppp_set_compress(ppp, arg);
 661                 break;
 662
 663         case PPPIOCGUNIT:
 664                 if (put_user(ppp->file.index, p))
 665                         break;
 666                 err = 0;
 667                 break;
 668
 669         case PPPIOCSDEBUG:
 670                 if (get_user(val, p))
 671                         break;
 672                 ppp->debug = val;
 673                 err = 0;
 674                 break;
 675
 676         case PPPIOCGDEBUG:
 677                 if (put_user(ppp->debug, p))
 678                         break;
 679                 err = 0;
 680                 break;
 681
 682         case PPPIOCGIDLE:
 683                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 684                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
 685                 if (copy_to_user(argp, &idle, sizeof(idle)))
 686                         break;
 687                 err = 0;
 688                 break;
 689
 690         case PPPIOCSMAXCID:
 691                 if (get_user(val, p))
 692                         break;
 693                 val2 = 15;
 694                 if ((val >> 16) != 0) {
 695                         val2 = val >> 16;
 696                         val &= 0xffff;
 697                 }
 698                 vj = slhc_init(val2+1, val+1);
 699                 if (!vj) {
 700                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
 701                         err = -ENOMEM;
 702                         break;
 703                 }
 704                 ppp_lock(ppp);
 705                 if (ppp->vj)
 706                         slhc_free(ppp->vj);
 707                 ppp->vj = vj;
 708                 ppp_unlock(ppp);
 709                 err = 0;
 710                 break;
 711
 712         case PPPIOCGNPMODE:
 713         case PPPIOCSNPMODE:
 714                 if (copy_from_user(&npi, argp, sizeof(npi)))
 715                         break;
 716                 err = proto_to_npindex(npi.protocol);
 717                 if (err < 0)
 718                         break;
 719                 i = err;
 720                 if (cmd == PPPIOCGNPMODE) {
 721                         err = -EFAULT;
 722                         npi.mode = ppp->npmode[i];
 723                         if (copy_to_user(argp, &npi, sizeof(npi)))
 724                                 break;
 725                 } else {
 726                         ppp->npmode[i] = npi.mode;
 727                         /* we may be able to transmit more packets now (??) */
 728                         netif_wake_queue(ppp->dev);
 729                 }
 730                 err = 0;
 731                 break;
 732
 733 #ifdef CONFIG_PPP_FILTER
 734         case PPPIOCSPASS:
 735         {
 736                 struct sock_filter *code;
 737                 err = get_filter(argp, &code);
 738                 if (err >= 0) {
 739                         ppp_lock(ppp);
 740                         kfree(ppp->pass_filter);
 741                         ppp->pass_filter = code;
 742                         ppp->pass_len = err;
 743                         ppp_unlock(ppp);
 744                         err = 0;
 745                 }
 746                 break;
 747         }
 748         case PPPIOCSACTIVE:
 749         {
 750                 struct sock_filter *code;
 751                 err = get_filter(argp, &code);
 752                 if (err >= 0) {
 753                         ppp_lock(ppp);
 754                         kfree(ppp->active_filter);
 755                         ppp->active_filter = code;
 756                         ppp->active_len = err;
 757                         ppp_unlock(ppp);
 758                         err = 0;
 759                 }
 760                 break;
 761         }
 762 #endif /* CONFIG_PPP_FILTER */
 763
 764 #ifdef CONFIG_PPP_MULTILINK
 765         case PPPIOCSMRRU:
 766                 if (get_user(val, p))
 767                         break;
 768                 ppp_recv_lock(ppp);
 769                 ppp->mrru = val;
 770                 ppp_recv_unlock(ppp);
 771                 err = 0;
 772                 break;
 773 #endif /* CONFIG_PPP_MULTILINK */
 774
 775         default:
 776                 err = -ENOTTY;
 777         }
 778         unlock_kernel();
 779         return err;
 780 }
 781
 782 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 783                                 unsigned int cmd, unsigned long arg)
 784 {
 785         int unit, err = -EFAULT;
 786         struct ppp *ppp;
 787         struct channel *chan;
 788         int __user *p = (int __user *)arg;
 789
 790         lock_kernel();
 791         switch (cmd) {
 792         case PPPIOCNEWUNIT:
 793                 /* Create a new ppp unit */
 794                 if (get_user(unit, p))
 795                         break;
 796                 ppp = ppp_create_interface(unit, &err);
 797                 if (!ppp)
 798                         break;
 799                 file->private_data = &ppp->file;
 800                 ppp->owner = file;
 801                 err = -EFAULT;
 802                 if (put_user(ppp->file.index, p))
 803                         break;
 804                 err = 0;
 805                 break;
 806
 807         case PPPIOCATTACH:
 808                 /* Attach to an existing ppp unit */
 809                 if (get_user(unit, p))
 810                         break;
 811                 mutex_lock(&all_ppp_mutex);
 812                 err = -ENXIO;
 813                 ppp = ppp_find_unit(unit);
 814                 if (ppp) {
 815                         atomic_inc(&ppp->file.refcnt);
 816                         file->private_data = &ppp->file;
 817                         err = 0;
 818                 }
 819                 mutex_unlock(&all_ppp_mutex);
 820                 break;
 821
 822         case PPPIOCATTCHAN:
 823                 if (get_user(unit, p))
 824                         break;
 825                 spin_lock_bh(&all_channels_lock);
 826                 err = -ENXIO;
 827                 chan = ppp_find_channel(unit);
 828                 if (chan) {
 829                         atomic_inc(&chan->file.refcnt);
 830                         file->private_data = &chan->file;
 831                         err = 0;
 832                 }
 833                 spin_unlock_bh(&all_channels_lock);
 834                 break;
 835
 836         default:
 837                 err = -ENOTTY;
 838         }
 839         unlock_kernel();
 840         return err;
 841 }
 842
 843 static const struct file_operations ppp_device_fops = {
 844         .owner          = THIS_MODULE,
 845         .read           = ppp_read,
 846         .write          = ppp_write,
 847         .poll           = ppp_poll,
 848         .unlocked_ioctl = ppp_ioctl,
 849         .open           = ppp_open,
 850         .release        = ppp_release
 851 };
 852
 853 #define PPP_MAJOR       108
 854
 855 /* Called at boot time if ppp is compiled into the kernel,
 856    or at module load time (from init_module) if compiled as a module. */
 857 static int __init ppp_init(void)
 858 {
 859         int err;
 860
 861         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
 862         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
 863         if (!err) {
 864                 ppp_class = class_create(THIS_MODULE, "ppp");
 865                 if (IS_ERR(ppp_class)) {
 866                         err = PTR_ERR(ppp_class);
 867                         goto out_chrdev;
 868                 }
 869                 device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL,
 870                               "ppp");
 871         }
 872
 873 out:
 874         if (err)
 875                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
 876         return err;
 877
 878 out_chrdev:
 879         unregister_chrdev(PPP_MAJOR, "ppp");
 880         goto out;
 881 }
 882
 883 /*
 884  * Network interface unit routines.
 885  */
 886 static int
 887 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 888 {
 889         struct ppp *ppp = (struct ppp *) dev->priv;
 890         int npi, proto;
 891         unsigned char *pp;
 892
 893         npi = ethertype_to_npindex(ntohs(skb->protocol));
 894         if (npi < 0)
 895                 goto outf;
 896
 897         /* Drop, accept or reject the packet */
 898         switch (ppp->npmode[npi]) {
 899         case NPMODE_PASS:
 900                 break;
 901         case NPMODE_QUEUE:
 902                 /* it would be nice to have a way to tell the network
 903                    system to queue this one up for later. */
 904                 goto outf;
 905         case NPMODE_DROP:
 906         case NPMODE_ERROR:
 907                 goto outf;
 908         }
 909
 910         /* Put the 2-byte PPP protocol number on the front,
 911            making sure there is room for the address and control fields. */
 912         if (skb_cow_head(skb, PPP_HDRLEN))
 913                 goto outf;
 914
 915         pp = skb_push(skb, 2);
 916         proto = npindex_to_proto[npi];
 917         pp[0] = proto >> 8;
 918         pp[1] = proto;
 919
 920         netif_stop_queue(dev);
 921         skb_queue_tail(&ppp->file.xq, skb);
 922         ppp_xmit_process(ppp);
 923         return 0;
 924
 925  outf:
 926         kfree_skb(skb);
 927         ++ppp->dev->stats.tx_dropped;
 928         return 0;
 929 }
 930
 931 static int
 932 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 933 {
 934         struct ppp *ppp = dev->priv;
 935         int err = -EFAULT;
 936         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
 937         struct ppp_stats stats;
 938         struct ppp_comp_stats cstats;
 939         char *vers;
 940
 941         switch (cmd) {
 942         case SIOCGPPPSTATS:
 943                 ppp_get_stats(ppp, &stats);
 944                 if (copy_to_user(addr, &stats, sizeof(stats)))
 945                         break;
 946                 err = 0;
 947                 break;
 948
 949         case SIOCGPPPCSTATS:
 950                 memset(&cstats, 0, sizeof(cstats));
 951                 if (ppp->xc_state)
 952                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
 953                 if (ppp->rc_state)
 954                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
 955                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
 956                         break;
 957                 err = 0;
 958                 break;
 959
 960         case SIOCGPPPVER:
 961                 vers = PPP_VERSION;
 962                 if (copy_to_user(addr, vers, strlen(vers) + 1))
 963                         break;
 964                 err = 0;
 965                 break;
 966
 967         default:
 968                 err = -EINVAL;
 969         }
 970
 971         return err;
 972 }
 973
 974 static void ppp_setup(struct net_device *dev)
 975 {
 976         dev->hard_header_len = PPP_HDRLEN;
 977         dev->mtu = PPP_MTU;
 978         dev->addr_len = 0;
 979         dev->tx_queue_len = 3;
 980         dev->type = ARPHRD_PPP;
 981         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
 982 }
 983
 984 /*
 985  * Transmit-side routines.
 986  */
 987
 988 /*
 989  * Called to do any work queued up on the transmit side
 990  * that can now be done.
 991  */
 992 static void
 993 ppp_xmit_process(struct ppp *ppp)
 994 {
 995         struct sk_buff *skb;
 996
 997         ppp_xmit_lock(ppp);
 998         if (ppp->dev) {
 999                 ppp_push(ppp);
1000                 while (!ppp->xmit_pending
1001                        && (skb = skb_dequeue(&ppp->file.xq)))
1002                         ppp_send_frame(ppp, skb);
1003                 /* If there's no work left to do, tell the core net
1004                    code that we can accept some more. */
1005                 if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
1006                         netif_wake_queue(ppp->dev);
1007         }
1008         ppp_xmit_unlock(ppp);
1009 }
1010
1011 static inline struct sk_buff *
1012 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1013 {
1014         struct sk_buff *new_skb;
1015         int len;
1016         int new_skb_size = ppp->dev->mtu +
1017                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1018         int compressor_skb_size = ppp->dev->mtu +
1019                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1020         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1021         if (!new_skb) {
1022                 if (net_ratelimit())
1023                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1024                 return NULL;
1025         }
1026         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1027                 skb_reserve(new_skb,
1028                             ppp->dev->hard_header_len - PPP_HDRLEN);
1029
1030         /* compressor still expects A/C bytes in hdr */
1031         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1032                                    new_skb->data, skb->len + 2,
1033                                    compressor_skb_size);
1034         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1035                 kfree_skb(skb);
1036                 skb = new_skb;
1037                 skb_put(skb, len);
1038                 skb_pull(skb, 2);       /* pull off A/C bytes */
1039         } else if (len == 0) {
1040                 /* didn't compress, or CCP not up yet */
1041                 kfree_skb(new_skb);
1042                 new_skb = skb;
1043         } else {
1044                 /*
1045                  * (len < 0)
1046                  * MPPE requires that we do not send unencrypted
1047                  * frames.  The compressor will return -1 if we
1048                  * should drop the frame.  We cannot simply test
1049                  * the compress_proto because MPPE and MPPC share
1050                  * the same number.
1051                  */
1052                 if (net_ratelimit())
1053                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1054                 kfree_skb(skb);
1055                 kfree_skb(new_skb);
1056                 new_skb = NULL;
1057         }
1058         return new_skb;
1059 }
1060
1061 /*
1062  * Compress and send a frame.
1063  * The caller should have locked the xmit path,
1064  * and xmit_pending should be 0.
1065  */
1066 static void
1067 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1068 {
1069         int proto = PPP_PROTO(skb);
1070         struct sk_buff *new_skb;
1071         int len;
1072         unsigned char *cp;
1073
1074         if (proto < 0x8000) {
1075 #ifdef CONFIG_PPP_FILTER
1076                 /* check if we should pass this packet */
1077                 /* the filter instructions are constructed assuming
1078                    a four-byte PPP header on each packet */
1079                 *skb_push(skb, 2) = 1;
1080                 if (ppp->pass_filter
1081                     && sk_run_filter(skb, ppp->pass_filter,
1082                                      ppp->pass_len) == 0) {
1083                         if (ppp->debug & 1)
1084                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1085                         kfree_skb(skb);
1086                         return;
1087                 }
1088                 /* if this packet passes the active filter, record the time */
1089                 if (!(ppp->active_filter
1090                       && sk_run_filter(skb, ppp->active_filter,
1091                                        ppp->active_len) == 0))
1092                         ppp->last_xmit = jiffies;
1093                 skb_pull(skb, 2);
1094 #else
1095                 /* for data packets, record the time */
1096                 ppp->last_xmit = jiffies;
1097 #endif /* CONFIG_PPP_FILTER */
1098         }
1099
1100         ++ppp->dev->stats.tx_packets;
1101         ppp->dev->stats.tx_bytes += skb->len - 2;
1102
1103         switch (proto) {
1104         case PPP_IP:
1105                 if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1106                         break;
1107                 /* try to do VJ TCP header compression */
1108                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1109                                     GFP_ATOMIC);
1110                 if (!new_skb) {
1111                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1112                         goto drop;
1113                 }
1114                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1115                 cp = skb->data + 2;
1116                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1117                                     new_skb->data + 2, &cp,
1118                                     !(ppp->flags & SC_NO_TCP_CCID));
1119                 if (cp == skb->data + 2) {
1120                         /* didn't compress */
1121                         kfree_skb(new_skb);
1122                 } else {
1123                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1124                                 proto = PPP_VJC_COMP;
1125                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1126                         } else {
1127                                 proto = PPP_VJC_UNCOMP;
1128                                 cp[0] = skb->data[2];
1129                         }
1130                         kfree_skb(skb);
1131                         skb = new_skb;
1132                         cp = skb_put(skb, len + 2);
1133                         cp[0] = 0;
1134                         cp[1] = proto;
1135                 }
1136                 break;
1137
1138         case PPP_CCP:
1139                 /* peek at outbound CCP frames */
1140                 ppp_ccp_peek(ppp, skb, 0);
1141                 break;
1142         }
1143
1144         /* try to do packet compression */
1145         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state
1146             && proto != PPP_LCP && proto != PPP_CCP) {
1147                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1148                         if (net_ratelimit())
1149                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1150                         goto drop;
1151                 }
1152                 skb = pad_compress_skb(ppp, skb);
1153                 if (!skb)
1154                         goto drop;
1155         }
1156
1157         /*
1158          * If we are waiting for traffic (demand dialling),
1159          * queue it up for pppd to receive.
1160          */
1161         if (ppp->flags & SC_LOOP_TRAFFIC) {
1162                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1163                         goto drop;
1164                 skb_queue_tail(&ppp->file.rq, skb);
1165                 wake_up_interruptible(&ppp->file.rwait);
1166                 return;
1167         }
1168
1169         ppp->xmit_pending = skb;
1170         ppp_push(ppp);
1171         return;
1172
1173  drop:
1174         if (skb)
1175                 kfree_skb(skb);
1176         ++ppp->dev->stats.tx_errors;
1177 }
1178
1179 /*
1180  * Try to send the frame in xmit_pending.
1181  * The caller should have the xmit path locked.
1182  */
1183 static void
1184 ppp_push(struct ppp *ppp)
1185 {
1186         struct list_head *list;
1187         struct channel *pch;
1188         struct sk_buff *skb = ppp->xmit_pending;
1189
1190         if (!skb)
1191                 return;
1192
1193         list = &ppp->channels;
1194         if (list_empty(list)) {
1195                 /* nowhere to send the packet, just drop it */
1196                 ppp->xmit_pending = NULL;
1197                 kfree_skb(skb);
1198                 return;
1199         }
1200
1201         if ((ppp->flags & SC_MULTILINK) == 0) {
1202                 /* not doing multilink: send it down the first channel */
1203                 list = list->next;
1204                 pch = list_entry(list, struct channel, clist);
1205
1206                 spin_lock_bh(&pch->downl);
1207                 if (pch->chan) {
1208                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1209                                 ppp->xmit_pending = NULL;
1210                 } else {
1211                         /* channel got unregistered */
1212                         kfree_skb(skb);
1213                         ppp->xmit_pending = NULL;
1214                 }
1215                 spin_unlock_bh(&pch->downl);
1216                 return;
1217         }
1218
1219 #ifdef CONFIG_PPP_MULTILINK
1220         /* Multilink: fragment the packet over as many links
1221            as can take the packet at the moment. */
1222         if (!ppp_mp_explode(ppp, skb))
1223                 return;
1224 #endif /* CONFIG_PPP_MULTILINK */
1225
1226         ppp->xmit_pending = NULL;
1227         kfree_skb(skb);
1228 }
1229
1230 #ifdef CONFIG_PPP_MULTILINK
1231 /*
1232  * Divide a packet to be transmitted into fragments and
1233  * send them out the individual links.
1234  */
1235 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1236 {
1237         int len, fragsize;
1238         int i, bits, hdrlen, mtu;
1239         int flen;
1240         int navail, nfree;
1241         int nbigger;
1242         unsigned char *p, *q;
1243         struct list_head *list;
1244         struct channel *pch;
1245         struct sk_buff *frag;
1246         struct ppp_channel *chan;
1247
1248         nfree = 0;      /* # channels which have no packet already queued */
1249         navail = 0;     /* total # of usable channels (not deregistered) */
1250         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1251         i = 0;
1252         list_for_each_entry(pch, &ppp->channels, clist) {
1253                 navail += pch->avail = (pch->chan != NULL);
1254                 if (pch->avail) {
1255                         if (skb_queue_empty(&pch->file.xq) ||
1256                             !pch->had_frag) {
1257                                 pch->avail = 2;
1258                                 ++nfree;
1259                         }
1260                         if (!pch->had_frag && i < ppp->nxchan)
1261                                 ppp->nxchan = i;
1262                 }
1263                 ++i;
1264         }
1265
1266         /*
1267          * Don't start sending this packet unless at least half of
1268          * the channels are free.  This gives much better TCP
1269          * performance if we have a lot of channels.
1270          */
1271         if (nfree == 0 || nfree < navail / 2)
1272                 return 0;       /* can't take now, leave it in xmit_pending */
1273
1274         /* Do protocol field compression (XXX this should be optional) */
1275         p = skb->data;
1276         len = skb->len;
1277         if (*p == 0) {
1278                 ++p;
1279                 --len;
1280         }
1281
1282         /*
1283          * Decide on fragment size.
1284          * We create a fragment for each free channel regardless of
1285          * how small they are (i.e. even 0 length) in order to minimize
1286          * the time that it will take to detect when a channel drops
1287          * a fragment.
1288          */
1289         fragsize = len;
1290         if (nfree > 1)
1291                 fragsize = DIV_ROUND_UP(fragsize, nfree);
1292         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1293            except if nbigger==0, then they all get fragsize. */
1294         nbigger = len % nfree;
1295
1296         /* skip to the channel after the one we last used
1297            and start at that one */
1298         list = &ppp->channels;
1299         for (i = 0; i < ppp->nxchan; ++i) {
1300                 list = list->next;
1301                 if (list == &ppp->channels) {
1302                         i = 0;
1303                         break;
1304                 }
1305         }
1306
1307         /* create a fragment for each channel */
1308         bits = B;
1309         while (nfree > 0 || len > 0) {
1310                 list = list->next;
1311                 if (list == &ppp->channels) {
1312                         i = 0;
1313                         continue;
1314                 }
1315                 pch = list_entry(list, struct channel, clist);
1316                 ++i;
1317                 if (!pch->avail)
1318                         continue;
1319
1320                 /*
1321                  * Skip this channel if it has a fragment pending already and
1322                  * we haven't given a fragment to all of the free channels.
1323                  */
1324                 if (pch->avail == 1) {
1325                         if (nfree > 0)
1326                                 continue;
1327                 } else {
1328                         --nfree;
1329                         pch->avail = 1;
1330                 }
1331
1332                 /* check the channel's mtu and whether it is still attached. */
1333                 spin_lock_bh(&pch->downl);
1334                 if (pch->chan == NULL) {
1335                         /* can't use this channel, it's being deregistered */
1336                         spin_unlock_bh(&pch->downl);
1337                         pch->avail = 0;
1338                         if (--navail == 0)
1339                                 break;
1340                         continue;
1341                 }
1342
1343                 /*
1344                  * Create a fragment for this channel of
1345                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1346                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1347                  * MTU, so we use mtu = 2 + hdrlen.
1348                  */
1349                 if (fragsize > len)
1350                         fragsize = len;
1351                 flen = fragsize;
1352                 mtu = pch->chan->mtu + 2 - hdrlen;
1353                 if (mtu < 4)
1354                         mtu = 4;
1355                 if (flen > mtu)
1356                         flen = mtu;
1357                 if (flen == len && nfree == 0)
1358                         bits |= E;
1359                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1360                 if (!frag)
1361                         goto noskb;
1362                 q = skb_put(frag, flen + hdrlen);
1363
1364                 /* make the MP header */
1365                 q[0] = PPP_MP >> 8;
1366                 q[1] = PPP_MP;
1367                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1368                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1369                         q[3] = ppp->nxseq;
1370                 } else {
1371                         q[2] = bits;
1372                         q[3] = ppp->nxseq >> 16;
1373                         q[4] = ppp->nxseq >> 8;
1374                         q[5] = ppp->nxseq;
1375                 }
1376
1377                 /*
1378                  * Copy the data in.
1379                  * Unfortunately there is a bug in older versions of
1380                  * the Linux PPP multilink reconstruction code where it
1381                  * drops 0-length fragments.  Therefore we make sure the
1382                  * fragment has at least one byte of data.  Any bytes
1383                  * we add in this situation will end up as padding on the
1384                  * end of the reconstructed packet.
1385                  */
1386                 if (flen == 0)
1387                         *skb_put(frag, 1) = 0;
1388                 else
1389                         memcpy(q + hdrlen, p, flen);
1390
1391                 /* try to send it down the channel */
1392                 chan = pch->chan;
1393                 if (!skb_queue_empty(&pch->file.xq) ||
1394                     !chan->ops->start_xmit(chan, frag))
1395                         skb_queue_tail(&pch->file.xq, frag);
1396                 pch->had_frag = 1;
1397                 p += flen;
1398                 len -= flen;
1399                 ++ppp->nxseq;
1400                 bits = 0;
1401                 spin_unlock_bh(&pch->downl);
1402
1403                 if (--nbigger == 0 && fragsize > 0)
1404                         --fragsize;
1405         }
1406         ppp->nxchan = i;
1407
1408         return 1;
1409
1410  noskb:
1411         spin_unlock_bh(&pch->downl);
1412         if (ppp->debug & 1)
1413                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1414         ++ppp->dev->stats.tx_errors;
1415         ++ppp->nxseq;
1416         return 1;       /* abandon the frame */
1417 }
1418 #endif /* CONFIG_PPP_MULTILINK */
1419
1420 /*
1421  * Try to send data out on a channel.
1422  */
1423 static void
1424 ppp_channel_push(struct channel *pch)
1425 {
1426         struct sk_buff *skb;
1427         struct ppp *ppp;
1428
1429         spin_lock_bh(&pch->downl);
1430         if (pch->chan) {
1431                 while (!skb_queue_empty(&pch->file.xq)) {
1432                         skb = skb_dequeue(&pch->file.xq);
1433                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1434                                 /* put the packet back and try again later */
1435                                 skb_queue_head(&pch->file.xq, skb);
1436                                 break;
1437                         }
1438                 }
1439         } else {
1440                 /* channel got deregistered */
1441                 skb_queue_purge(&pch->file.xq);
1442         }
1443         spin_unlock_bh(&pch->downl);
1444         /* see if there is anything from the attached unit to be sent */
1445         if (skb_queue_empty(&pch->file.xq)) {
1446                 read_lock_bh(&pch->upl);
1447                 ppp = pch->ppp;
1448                 if (ppp)
1449                         ppp_xmit_process(ppp);
1450                 read_unlock_bh(&pch->upl);
1451         }
1452 }
1453
1454 /*
1455  * Receive-side routines.
1456  */
1457
1458 /* misuse a few fields of the skb for MP reconstruction */
1459 #define sequence        priority
1460 #define BEbits          cb[0]
1461
1462 static inline void
1463 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1464 {
1465         ppp_recv_lock(ppp);
1466         /* ppp->dev == 0 means interface is closing down */
1467         if (ppp->dev)
1468                 ppp_receive_frame(ppp, skb, pch);
1469         else
1470                 kfree_skb(skb);
1471         ppp_recv_unlock(ppp);
1472 }
1473
1474 void
1475 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1476 {
1477         struct channel *pch = chan->ppp;
1478         int proto;
1479
1480         if (!pch || skb->len == 0) {
1481                 kfree_skb(skb);
1482                 return;
1483         }
1484
1485         proto = PPP_PROTO(skb);
1486         read_lock_bh(&pch->upl);
1487         if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1488                 /* put it on the channel queue */
1489                 skb_queue_tail(&pch->file.rq, skb);
1490                 /* drop old frames if queue too long */
1491                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1492                        && (skb = skb_dequeue(&pch->file.rq)))
1493                         kfree_skb(skb);
1494                 wake_up_interruptible(&pch->file.rwait);
1495         } else {
1496                 ppp_do_recv(pch->ppp, skb, pch);
1497         }
1498         read_unlock_bh(&pch->upl);
1499 }
1500
1501 /* Put a 0-length skb in the receive queue as an error indication */
1502 void
1503 ppp_input_error(struct ppp_channel *chan, int code)
1504 {
1505         struct channel *pch = chan->ppp;
1506         struct sk_buff *skb;
1507
1508         if (!pch)
1509                 return;
1510
1511         read_lock_bh(&pch->upl);
1512         if (pch->ppp) {
1513                 skb = alloc_skb(0, GFP_ATOMIC);
1514                 if (skb) {
1515                         skb->len = 0;           /* probably unnecessary */
1516                         skb->cb[0] = code;
1517                         ppp_do_recv(pch->ppp, skb, pch);
1518                 }
1519         }
1520         read_unlock_bh(&pch->upl);
1521 }
1522
1523 /*
1524  * We come in here to process a received frame.
1525  * The receive side of the ppp unit is locked.
1526  */
1527 static void
1528 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1529 {
1530         if (pskb_may_pull(skb, 2)) {
1531 #ifdef CONFIG_PPP_MULTILINK
1532                 /* XXX do channel-level decompression here */
1533                 if (PPP_PROTO(skb) == PPP_MP)
1534                         ppp_receive_mp_frame(ppp, skb, pch);
1535                 else
1536 #endif /* CONFIG_PPP_MULTILINK */
1537                         ppp_receive_nonmp_frame(ppp, skb);
1538                 return;
1539         }
1540
1541         if (skb->len > 0)
1542                 /* note: a 0-length skb is used as an error indication */
1543                 ++ppp->dev->stats.rx_length_errors;
1544
1545         kfree_skb(skb);
1546         ppp_receive_error(ppp);
1547 }
1548
1549 static void
1550 ppp_receive_error(struct ppp *ppp)
1551 {
1552         ++ppp->dev->stats.rx_errors;
1553         if (ppp->vj)
1554                 slhc_toss(ppp->vj);
1555 }
1556
1557 static void
1558 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1559 {
1560         struct sk_buff *ns;
1561         int proto, len, npi;
1562
1563         /*
1564          * Decompress the frame, if compressed.
1565          * Note that some decompressors need to see uncompressed frames
1566          * that come in as well as compressed frames.
1567          */
1568         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)
1569             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1570                 skb = ppp_decompress_frame(ppp, skb);
1571
1572         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1573                 goto err;
1574
1575         proto = PPP_PROTO(skb);
1576         switch (proto) {
1577         case PPP_VJC_COMP:
1578                 /* decompress VJ compressed packets */
1579                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1580                         goto err;
1581
1582                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1583                         /* copy to a new sk_buff with more tailroom */
1584                         ns = dev_alloc_skb(skb->len + 128);
1585                         if (!ns) {
1586                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1587                                 goto err;
1588                         }
1589                         skb_reserve(ns, 2);
1590                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1591                         kfree_skb(skb);
1592                         skb = ns;
1593                 }
1594                 else
1595                         skb->ip_summed = CHECKSUM_NONE;
1596
1597                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1598                 if (len <= 0) {
1599                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1600                         goto err;
1601                 }
1602                 len += 2;
1603                 if (len > skb->len)
1604                         skb_put(skb, len - skb->len);
1605                 else if (len < skb->len)
1606                         skb_trim(skb, len);
1607                 proto = PPP_IP;
1608                 break;
1609
1610         case PPP_VJC_UNCOMP:
1611                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1612                         goto err;
1613
1614                 /* Until we fix the decompressor need to make sure
1615                  * data portion is linear.
1616                  */
1617                 if (!pskb_may_pull(skb, skb->len))
1618                         goto err;
1619
1620                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1621                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1622                         goto err;
1623                 }
1624                 proto = PPP_IP;
1625                 break;
1626
1627         case PPP_CCP:
1628                 ppp_ccp_peek(ppp, skb, 1);
1629                 break;
1630         }
1631
1632         ++ppp->dev->stats.rx_packets;
1633         ppp->dev->stats.rx_bytes += skb->len - 2;
1634
1635         npi = proto_to_npindex(proto);
1636         if (npi < 0) {
1637                 /* control or unknown frame - pass it to pppd */
1638                 skb_queue_tail(&ppp->file.rq, skb);
1639                 /* limit queue length by dropping old frames */
1640                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1641                        && (skb = skb_dequeue(&ppp->file.rq)))
1642                         kfree_skb(skb);
1643                 /* wake up any process polling or blocking on read */
1644                 wake_up_interruptible(&ppp->file.rwait);
1645
1646         } else {
1647                 /* network protocol frame - give it to the kernel */
1648
1649 #ifdef CONFIG_PPP_FILTER
1650                 /* check if the packet passes the pass and active filters */
1651                 /* the filter instructions are constructed assuming
1652                    a four-byte PPP header on each packet */
1653                 if (ppp->pass_filter || ppp->active_filter) {
1654                         if (skb_cloned(skb) &&
1655                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
1656                                 goto err;
1657
1658                         *skb_push(skb, 2) = 0;
1659                         if (ppp->pass_filter
1660                             && sk_run_filter(skb, ppp->pass_filter,
1661                                              ppp->pass_len) == 0) {
1662                                 if (ppp->debug & 1)
1663                                         printk(KERN_DEBUG "PPP: inbound frame "
1664                                                "not passed\n");
1665                                 kfree_skb(skb);
1666                                 return;
1667                         }
1668                         if (!(ppp->active_filter
1669                               && sk_run_filter(skb, ppp->active_filter,
1670                                                ppp->active_len) == 0))
1671                                 ppp->last_recv = jiffies;
1672                         __skb_pull(skb, 2);
1673                 } else
1674 #endif /* CONFIG_PPP_FILTER */
1675                         ppp->last_recv = jiffies;
1676
1677                 if ((ppp->dev->flags & IFF_UP) == 0
1678                     || ppp->npmode[npi] != NPMODE_PASS) {
1679                         kfree_skb(skb);
1680                 } else {
1681                         /* chop off protocol */
1682                         skb_pull_rcsum(skb, 2);
1683                         skb->dev = ppp->dev;
1684                         skb->protocol = htons(npindex_to_ethertype[npi]);
1685                         skb_reset_mac_header(skb);
1686                         netif_rx(skb);
1687                         ppp->dev->last_rx = jiffies;
1688                 }
1689         }
1690         return;
1691
1692  err:
1693         kfree_skb(skb);
1694         ppp_receive_error(ppp);
1695 }
1696
1697 static struct sk_buff *
1698 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1699 {
1700         int proto = PPP_PROTO(skb);
1701         struct sk_buff *ns;
1702         int len;
1703
1704         /* Until we fix all the decompressor's need to make sure
1705          * data portion is linear.
1706          */
1707         if (!pskb_may_pull(skb, skb->len))
1708                 goto err;
1709
1710         if (proto == PPP_COMP) {
1711                 int obuff_size;
1712
1713                 switch(ppp->rcomp->compress_proto) {
1714                 case CI_MPPE:
1715                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1716                         break;
1717                 default:
1718                         obuff_size = ppp->mru + PPP_HDRLEN;
1719                         break;
1720                 }
1721
1722                 ns = dev_alloc_skb(obuff_size);
1723                 if (!ns) {
1724                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1725                         goto err;
1726                 }
1727                 /* the decompressor still expects the A/C bytes in the hdr */
1728                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1729                                 skb->len + 2, ns->data, obuff_size);
1730                 if (len < 0) {
1731                         /* Pass the compressed frame to pppd as an
1732                            error indication. */
1733                         if (len == DECOMP_FATALERROR)
1734                                 ppp->rstate |= SC_DC_FERROR;
1735                         kfree_skb(ns);
1736                         goto err;
1737                 }
1738
1739                 kfree_skb(skb);
1740                 skb = ns;
1741                 skb_put(skb, len);
1742                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1743
1744         } else {
1745                 /* Uncompressed frame - pass to decompressor so it
1746                    can update its dictionary if necessary. */
1747                 if (ppp->rcomp->incomp)
1748                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1749                                            skb->len + 2);
1750         }
1751
1752         return skb;
1753
1754  err:
1755         ppp->rstate |= SC_DC_ERROR;
1756         ppp_receive_error(ppp);
1757         return skb;
1758 }
1759
1760 #ifdef CONFIG_PPP_MULTILINK
1761 /*
1762  * Receive a multilink frame.
1763  * We put it on the reconstruction queue and then pull off
1764  * as many completed frames as we can.
1765  */
1766 static void
1767 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1768 {
1769         u32 mask, seq;
1770         struct channel *ch;
1771         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1772
1773         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1774                 goto err;               /* no good, throw it away */
1775
1776         /* Decode sequence number and begin/end bits */
1777         if (ppp->flags & SC_MP_SHORTSEQ) {
1778                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1779                 mask = 0xfff;
1780         } else {
1781                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1782                 mask = 0xffffff;
1783         }
1784         skb->BEbits = skb->data[2];
1785         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1786
1787         /*
1788          * Do protocol ID decompression on the first fragment of each packet.
1789          */
1790         if ((skb->BEbits & B) && (skb->data[0] & 1))
1791                 *skb_push(skb, 1) = 0;
1792
1793         /*
1794          * Expand sequence number to 32 bits, making it as close
1795          * as possible to ppp->minseq.
1796          */
1797         seq |= ppp->minseq & ~mask;
1798         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1799                 seq += mask + 1;
1800         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1801                 seq -= mask + 1;        /* should never happen */
1802         skb->sequence = seq;
1803         pch->lastseq = seq;
1804
1805         /*
1806          * If this packet comes before the next one we were expecting,
1807          * drop it.
1808          */
1809         if (seq_before(seq, ppp->nextseq)) {
1810                 kfree_skb(skb);
1811                 ++ppp->dev->stats.rx_dropped;
1812                 ppp_receive_error(ppp);
1813                 return;
1814         }
1815
1816         /*
1817          * Reevaluate minseq, the minimum over all channels of the
1818          * last sequence number received on each channel.  Because of
1819          * the increasing sequence number rule, we know that any fragment
1820          * before `minseq' which hasn't arrived is never going to arrive.
1821          * The list of channels can't change because we have the receive
1822          * side of the ppp unit locked.
1823          */
1824         list_for_each_entry(ch, &ppp->channels, clist) {
1825                 if (seq_before(ch->lastseq, seq))
1826                         seq = ch->lastseq;
1827         }
1828         if (seq_before(ppp->minseq, seq))
1829                 ppp->minseq = seq;
1830
1831         /* Put the fragment on the reconstruction queue */
1832         ppp_mp_insert(ppp, skb);
1833
1834         /* If the queue is getting long, don't wait any longer for packets
1835            before the start of the queue. */
1836         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN) {
1837                 struct sk_buff *skb = skb_peek(&ppp->mrq);
1838                 if (seq_before(ppp->minseq, skb->sequence))
1839                         ppp->minseq = skb->sequence;
1840         }
1841
1842         /* Pull completed packets off the queue and receive them. */
1843         while ((skb = ppp_mp_reconstruct(ppp)))
1844                 ppp_receive_nonmp_frame(ppp, skb);
1845
1846         return;
1847
1848  err:
1849         kfree_skb(skb);
1850         ppp_receive_error(ppp);
1851 }
1852
1853 /*
1854  * Insert a fragment on the MP reconstruction queue.
1855  * The queue is ordered by increasing sequence number.
1856  */
1857 static void
1858 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1859 {
1860         struct sk_buff *p;
1861         struct sk_buff_head *list = &ppp->mrq;
1862         u32 seq = skb->sequence;
1863
1864         /* N.B. we don't need to lock the list lock because we have the
1865            ppp unit receive-side lock. */
1866         skb_queue_walk(list, p) {
1867                 if (seq_before(seq, p->sequence))
1868                         break;
1869         }
1870         __skb_queue_before(list, p, skb);
1871 }
1872
1873 /*
1874  * Reconstruct a packet from the MP fragment queue.
1875  * We go through increasing sequence numbers until we find a
1876  * complete packet, or we get to the sequence number for a fragment
1877  * which hasn't arrived but might still do so.
1878  */
1879 static struct sk_buff *
1880 ppp_mp_reconstruct(struct ppp *ppp)
1881 {
1882         u32 seq = ppp->nextseq;
1883         u32 minseq = ppp->minseq;
1884         struct sk_buff_head *list = &ppp->mrq;
1885         struct sk_buff *p, *next;
1886         struct sk_buff *head, *tail;
1887         struct sk_buff *skb = NULL;
1888         int lost = 0, len = 0;
1889
1890         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1891                 return NULL;
1892         head = list->next;
1893         tail = NULL;
1894         for (p = head; p != (struct sk_buff *) list; p = next) {
1895                 next = p->next;
1896                 if (seq_before(p->sequence, seq)) {
1897                         /* this can't happen, anyway ignore the skb */
1898                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1899                                p->sequence, seq);
1900                         head = next;
1901                         continue;
1902                 }
1903                 if (p->sequence != seq) {
1904                         /* Fragment `seq' is missing.  If it is after
1905                            minseq, it might arrive later, so stop here. */
1906                         if (seq_after(seq, minseq))
1907                                 break;
1908                         /* Fragment `seq' is lost, keep going. */
1909                         lost = 1;
1910                         seq = seq_before(minseq, p->sequence)?
1911                                 minseq + 1: p->sequence;
1912                         next = p;
1913                         continue;
1914                 }
1915
1916                 /*
1917                  * At this point we know that all the fragments from
1918                  * ppp->nextseq to seq are either present or lost.
1919                  * Also, there are no complete packets in the queue
1920                  * that have no missing fragments and end before this
1921                  * fragment.
1922                  */
1923
1924                 /* B bit set indicates this fragment starts a packet */
1925                 if (p->BEbits & B) {
1926                         head = p;
1927                         lost = 0;
1928                         len = 0;
1929                 }
1930
1931                 len += p->len;
1932
1933                 /* Got a complete packet yet? */
1934                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1935                         if (len > ppp->mrru + 2) {
1936                                 ++ppp->dev->stats.rx_length_errors;
1937                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1938                                        " is too long (%d)\n", len);
1939                         } else if (p == head) {
1940                                 /* fragment is complete packet - reuse skb */
1941                                 tail = p;
1942                                 skb = skb_get(p);
1943                                 break;
1944                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1945                                 ++ppp->dev->stats.rx_missed_errors;
1946                                 printk(KERN_DEBUG "PPP: no memory for "
1947                                        "reconstructed packet");
1948                         } else {
1949                                 tail = p;
1950                                 break;
1951                         }
1952                         ppp->nextseq = seq + 1;
1953                 }
1954
1955                 /*
1956                  * If this is the ending fragment of a packet,
1957                  * and we haven't found a complete valid packet yet,
1958                  * we can discard up to and including this fragment.
1959                  */
1960                 if (p->BEbits & E)
1961                         head = next;
1962
1963                 ++seq;
1964         }
1965
1966         /* If we have a complete packet, copy it all into one skb. */
1967         if (tail != NULL) {
1968                 /* If we have discarded any fragments,
1969                    signal a receive error. */
1970                 if (head->sequence != ppp->nextseq) {
1971                         if (ppp->debug & 1)
1972                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1973                                        ppp->nextseq, head->sequence-1);
1974                         ++ppp->dev->stats.rx_dropped;
1975                         ppp_receive_error(ppp);
1976                 }
1977
1978                 if (head != tail)
1979                         /* copy to a single skb */
1980                         for (p = head; p != tail->next; p = p->next)
1981                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1982                 ppp->nextseq = tail->sequence + 1;
1983                 head = tail->next;
1984         }
1985
1986         /* Discard all the skbuffs that we have copied the data out of
1987            or that we can't use. */
1988         while ((p = list->next) != head) {
1989                 __skb_unlink(p, list);
1990                 kfree_skb(p);
1991         }
1992
1993         return skb;
1994 }
1995 #endif /* CONFIG_PPP_MULTILINK */
1996
1997 /*
1998  * Channel interface.
1999  */
2000
2001 /*
2002  * Create a new, unattached ppp channel.
2003  */
2004 int
2005 ppp_register_channel(struct ppp_channel *chan)
2006 {
2007         struct channel *pch;
2008
2009         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2010         if (!pch)
2011                 return -ENOMEM;
2012         pch->ppp = NULL;
2013         pch->chan = chan;
2014         chan->ppp = pch;
2015         init_ppp_file(&pch->file, CHANNEL);
2016         pch->file.hdrlen = chan->hdrlen;
2017 #ifdef CONFIG_PPP_MULTILINK
2018         pch->lastseq = -1;
2019 #endif /* CONFIG_PPP_MULTILINK */
2020         init_rwsem(&pch->chan_sem);
2021         spin_lock_init(&pch->downl);
2022         rwlock_init(&pch->upl);
2023         spin_lock_bh(&all_channels_lock);
2024         pch->file.index = ++last_channel_index;
2025         list_add(&pch->list, &new_channels);
2026         atomic_inc(&channel_count);
2027         spin_unlock_bh(&all_channels_lock);
2028         return 0;
2029 }
2030
2031 /*
2032  * Return the index of a channel.
2033  */
2034 int ppp_channel_index(struct ppp_channel *chan)
2035 {
2036         struct channel *pch = chan->ppp;
2037
2038         if (pch)
2039                 return pch->file.index;
2040         return -1;
2041 }
2042
2043 /*
2044  * Return the PPP unit number to which a channel is connected.
2045  */
2046 int ppp_unit_number(struct ppp_channel *chan)
2047 {
2048         struct channel *pch = chan->ppp;
2049         int unit = -1;
2050
2051         if (pch) {
2052                 read_lock_bh(&pch->upl);
2053                 if (pch->ppp)
2054                         unit = pch->ppp->file.index;
2055                 read_unlock_bh(&pch->upl);
2056         }
2057         return unit;
2058 }
2059
2060 /*
2061  * Disconnect a channel from the generic layer.
2062  * This must be called in process context.
2063  */
2064 void
2065 ppp_unregister_channel(struct ppp_channel *chan)
2066 {
2067         struct channel *pch = chan->ppp;
2068
2069         if (!pch)
2070                 return;         /* should never happen */
2071         chan->ppp = NULL;
2072
2073         /*
2074          * This ensures that we have returned from any calls into the
2075          * the channel's start_xmit or ioctl routine before we proceed.
2076          */
2077         down_write(&pch->chan_sem);
2078         spin_lock_bh(&pch->downl);
2079         pch->chan = NULL;
2080         spin_unlock_bh(&pch->downl);
2081         up_write(&pch->chan_sem);
2082         ppp_disconnect_channel(pch);
2083         spin_lock_bh(&all_channels_lock);
2084         list_del(&pch->list);
2085         spin_unlock_bh(&all_channels_lock);
2086         pch->file.dead = 1;
2087         wake_up_interruptible(&pch->file.rwait);
2088         if (atomic_dec_and_test(&pch->file.refcnt))
2089                 ppp_destroy_channel(pch);
2090 }
2091
2092 /*
2093  * Callback from a channel when it can accept more to transmit.
2094  * This should be called at BH/softirq level, not interrupt level.
2095  */
2096 void
2097 ppp_output_wakeup(struct ppp_channel *chan)
2098 {
2099         struct channel *pch = chan->ppp;
2100
2101         if (!pch)
2102                 return;
2103         ppp_channel_push(pch);
2104 }
2105
2106 /*
2107  * Compression control.
2108  */
2109
2110 /* Process the PPPIOCSCOMPRESS ioctl. */
2111 static int
2112 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2113 {
2114         int err;
2115         struct compressor *cp, *ocomp;
2116         struct ppp_option_data data;
2117         void *state, *ostate;
2118         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2119
2120         err = -EFAULT;
2121         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2122             || (data.length <= CCP_MAX_OPTION_LENGTH
2123                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2124                 goto out;
2125         err = -EINVAL;
2126         if (data.length > CCP_MAX_OPTION_LENGTH
2127             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2128                 goto out;
2129
2130         cp = try_then_request_module(
2131                 find_compressor(ccp_option[0]),
2132                 "ppp-compress-%d", ccp_option[0]);
2133         if (!cp)
2134                 goto out;
2135
2136         err = -ENOBUFS;
2137         if (data.transmit) {
2138                 state = cp->comp_alloc(ccp_option, data.length);
2139                 if (state) {
2140                         ppp_xmit_lock(ppp);
2141                         ppp->xstate &= ~SC_COMP_RUN;
2142                         ocomp = ppp->xcomp;
2143                         ostate = ppp->xc_state;
2144                         ppp->xcomp = cp;
2145                         ppp->xc_state = state;
2146                         ppp_xmit_unlock(ppp);
2147                         if (ostate) {
2148                                 ocomp->comp_free(ostate);
2149                                 module_put(ocomp->owner);
2150                         }
2151                         err = 0;
2152                 } else
2153                         module_put(cp->owner);
2154
2155         } else {
2156                 state = cp->decomp_alloc(ccp_option, data.length);
2157                 if (state) {
2158                         ppp_recv_lock(ppp);
2159                         ppp->rstate &= ~SC_DECOMP_RUN;
2160                         ocomp = ppp->rcomp;
2161                         ostate = ppp->rc_state;
2162                         ppp->rcomp = cp;
2163                         ppp->rc_state = state;
2164                         ppp_recv_unlock(ppp);
2165                         if (ostate) {
2166                                 ocomp->decomp_free(ostate);
2167                                 module_put(ocomp->owner);
2168                         }
2169                         err = 0;
2170                 } else
2171                         module_put(cp->owner);
2172         }
2173
2174  out:
2175         return err;
2176 }
2177
2178 /*
2179  * Look at a CCP packet and update our state accordingly.
2180  * We assume the caller has the xmit or recv path locked.
2181  */
2182 static void
2183 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2184 {
2185         unsigned char *dp;
2186         int len;
2187
2188         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2189                 return; /* no header */
2190         dp = skb->data + 2;
2191
2192         switch (CCP_CODE(dp)) {
2193         case CCP_CONFREQ:
2194
2195                 /* A ConfReq starts negotiation of compression
2196                  * in one direction of transmission,
2197                  * and hence brings it down...but which way?
2198                  *
2199                  * Remember:
2200                  * A ConfReq indicates what the sender would like to receive
2201                  */
2202                 if(inbound)
2203                         /* He is proposing what I should send */
2204                         ppp->xstate &= ~SC_COMP_RUN;
2205                 else
2206                         /* I am proposing to what he should send */
2207                         ppp->rstate &= ~SC_DECOMP_RUN;
2208
2209                 break;
2210
2211         case CCP_TERMREQ:
2212         case CCP_TERMACK:
2213                 /*
2214                  * CCP is going down, both directions of transmission
2215                  */
2216                 ppp->rstate &= ~SC_DECOMP_RUN;
2217                 ppp->xstate &= ~SC_COMP_RUN;
2218                 break;
2219
2220         case CCP_CONFACK:
2221                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2222                         break;
2223                 len = CCP_LENGTH(dp);
2224                 if (!pskb_may_pull(skb, len + 2))
2225                         return;         /* too short */
2226                 dp += CCP_HDRLEN;
2227                 len -= CCP_HDRLEN;
2228                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2229                         break;
2230                 if (inbound) {
2231                         /* we will start receiving compressed packets */
2232                         if (!ppp->rc_state)
2233                                 break;
2234                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2235                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2236                                 ppp->rstate |= SC_DECOMP_RUN;
2237                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2238                         }
2239                 } else {
2240                         /* we will soon start sending compressed packets */
2241                         if (!ppp->xc_state)
2242                                 break;
2243                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2244                                         ppp->file.index, 0, ppp->debug))
2245                                 ppp->xstate |= SC_COMP_RUN;
2246                 }
2247                 break;
2248
2249         case CCP_RESETACK:
2250                 /* reset the [de]compressor */
2251                 if ((ppp->flags & SC_CCP_UP) == 0)
2252                         break;
2253                 if (inbound) {
2254                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2255                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2256                                 ppp->rstate &= ~SC_DC_ERROR;
2257                         }
2258                 } else {
2259                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2260                                 ppp->xcomp->comp_reset(ppp->xc_state);
2261                 }
2262                 break;
2263         }
2264 }
2265
2266 /* Free up compression resources. */
2267 static void
2268 ppp_ccp_closed(struct ppp *ppp)
2269 {
2270         void *xstate, *rstate;
2271         struct compressor *xcomp, *rcomp;
2272
2273         ppp_lock(ppp);
2274         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2275         ppp->xstate = 0;
2276         xcomp = ppp->xcomp;
2277         xstate = ppp->xc_state;
2278         ppp->xc_state = NULL;
2279         ppp->rstate = 0;
2280         rcomp = ppp->rcomp;
2281         rstate = ppp->rc_state;
2282         ppp->rc_state = NULL;
2283         ppp_unlock(ppp);
2284
2285         if (xstate) {
2286                 xcomp->comp_free(xstate);
2287                 module_put(xcomp->owner);
2288         }
2289         if (rstate) {
2290                 rcomp->decomp_free(rstate);
2291                 module_put(rcomp->owner);
2292         }
2293 }
2294
2295 /* List of compressors. */
2296 static LIST_HEAD(compressor_list);
2297 static DEFINE_SPINLOCK(compressor_list_lock);
2298
2299 struct compressor_entry {
2300         struct list_head list;
2301         struct compressor *comp;
2302 };
2303
2304 static struct compressor_entry *
2305 find_comp_entry(int proto)
2306 {
2307         struct compressor_entry *ce;
2308
2309         list_for_each_entry(ce, &compressor_list, list) {
2310                 if (ce->comp->compress_proto == proto)
2311                         return ce;
2312         }
2313         return NULL;
2314 }
2315
2316 /* Register a compressor */
2317 int
2318 ppp_register_compressor(struct compressor *cp)
2319 {
2320         struct compressor_entry *ce;
2321         int ret;
2322         spin_lock(&compressor_list_lock);
2323         ret = -EEXIST;
2324         if (find_comp_entry(cp->compress_proto))
2325                 goto out;
2326         ret = -ENOMEM;
2327         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2328         if (!ce)
2329                 goto out;
2330         ret = 0;
2331         ce->comp = cp;
2332         list_add(&ce->list, &compressor_list);
2333  out:
2334         spin_unlock(&compressor_list_lock);
2335         return ret;
2336 }
2337
2338 /* Unregister a compressor */
2339 void
2340 ppp_unregister_compressor(struct compressor *cp)
2341 {
2342         struct compressor_entry *ce;
2343
2344         spin_lock(&compressor_list_lock);
2345         ce = find_comp_entry(cp->compress_proto);
2346         if (ce && ce->comp == cp) {
2347                 list_del(&ce->list);
2348                 kfree(ce);
2349         }
2350         spin_unlock(&compressor_list_lock);
2351 }
2352
2353 /* Find a compressor. */
2354 static struct compressor *
2355 find_compressor(int type)
2356 {
2357         struct compressor_entry *ce;
2358         struct compressor *cp = NULL;
2359
2360         spin_lock(&compressor_list_lock);
2361         ce = find_comp_entry(type);
2362         if (ce) {
2363                 cp = ce->comp;
2364                 if (!try_module_get(cp->owner))
2365                         cp = NULL;
2366         }
2367         spin_unlock(&compressor_list_lock);
2368         return cp;
2369 }
2370
2371 /*
2372  * Miscelleneous stuff.
2373  */
2374
2375 static void
2376 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2377 {
2378         struct slcompress *vj = ppp->vj;
2379
2380         memset(st, 0, sizeof(*st));
2381         st->p.ppp_ipackets = ppp->dev->stats.rx_packets;
2382         st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2383         st->p.ppp_ibytes = ppp->dev->stats.rx_bytes;
2384         st->p.ppp_opackets = ppp->dev->stats.tx_packets;
2385         st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2386         st->p.ppp_obytes = ppp->dev->stats.tx_bytes;
2387         if (!vj)
2388                 return;
2389         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2390         st->vj.vjs_compressed = vj->sls_o_compressed;
2391         st->vj.vjs_searches = vj->sls_o_searches;
2392         st->vj.vjs_misses = vj->sls_o_misses;
2393         st->vj.vjs_errorin = vj->sls_i_error;
2394         st->vj.vjs_tossed = vj->sls_i_tossed;
2395         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2396         st->vj.vjs_compressedin = vj->sls_i_compressed;
2397 }
2398
2399 /*
2400  * Stuff for handling the lists of ppp units and channels
2401  * and for initialization.
2402  */
2403
2404 /*
2405  * Create a new ppp interface unit.  Fails if it can't allocate memory
2406  * or if there is already a unit with the requested number.
2407  * unit == -1 means allocate a new number.
2408  */
2409 static struct ppp *
2410 ppp_create_interface(int unit, int *retp)
2411 {
2412         struct ppp *ppp;
2413         struct net_device *dev = NULL;
2414         int ret = -ENOMEM;
2415         int i;
2416
2417         ppp = kzalloc(sizeof(struct ppp), GFP_KERNEL);
2418         if (!ppp)
2419                 goto out;
2420         dev = alloc_netdev(0, "", ppp_setup);
2421         if (!dev)
2422                 goto out1;
2423
2424         ppp->mru = PPP_MRU;
2425         init_ppp_file(&ppp->file, INTERFACE);
2426         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2427         for (i = 0; i < NUM_NP; ++i)
2428                 ppp->npmode[i] = NPMODE_PASS;
2429         INIT_LIST_HEAD(&ppp->channels);
2430         spin_lock_init(&ppp->rlock);
2431         spin_lock_init(&ppp->wlock);
2432 #ifdef CONFIG_PPP_MULTILINK
2433         ppp->minseq = -1;
2434         skb_queue_head_init(&ppp->mrq);
2435 #endif /* CONFIG_PPP_MULTILINK */
2436         ppp->dev = dev;
2437         dev->priv = ppp;
2438
2439         dev->hard_start_xmit = ppp_start_xmit;
2440         dev->do_ioctl = ppp_net_ioctl;
2441
2442         ret = -EEXIST;
2443         mutex_lock(&all_ppp_mutex);
2444         if (unit < 0)
2445                 unit = cardmap_find_first_free(all_ppp_units);
2446         else if (cardmap_get(all_ppp_units, unit) != NULL)
2447                 goto out2;      /* unit already exists */
2448
2449         /* Initialize the new ppp unit */
2450         ppp->file.index = unit;
2451         sprintf(dev->name, "ppp%d", unit);
2452
2453         ret = register_netdev(dev);
2454         if (ret != 0) {
2455                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2456                        dev->name, ret);
2457                 goto out2;
2458         }
2459
2460         atomic_inc(&ppp_unit_count);
2461         ret = cardmap_set(&all_ppp_units, unit, ppp);
2462         if (ret != 0)
2463                 goto out3;
2464
2465         mutex_unlock(&all_ppp_mutex);
2466         *retp = 0;
2467         return ppp;
2468
2469 out3:
2470         atomic_dec(&ppp_unit_count);
2471         unregister_netdev(dev);
2472 out2:
2473         mutex_unlock(&all_ppp_mutex);
2474         free_netdev(dev);
2475 out1:
2476         kfree(ppp);
2477 out:
2478         *retp = ret;
2479         return NULL;
2480 }
2481
2482 /*
2483  * Initialize a ppp_file structure.
2484  */
2485 static void
2486 init_ppp_file(struct ppp_file *pf, int kind)
2487 {
2488         pf->kind = kind;
2489         skb_queue_head_init(&pf->xq);
2490         skb_queue_head_init(&pf->rq);
2491         atomic_set(&pf->refcnt, 1);
2492         init_waitqueue_head(&pf->rwait);
2493 }
2494
2495 /*
2496  * Take down a ppp interface unit - called when the owning file
2497  * (the one that created the unit) is closed or detached.
2498  */
2499 static void ppp_shutdown_interface(struct ppp *ppp)
2500 {
2501         struct net_device *dev;
2502
2503         mutex_lock(&all_ppp_mutex);
2504         ppp_lock(ppp);
2505         dev = ppp->dev;
2506         ppp->dev = NULL;
2507         ppp_unlock(ppp);
2508         /* This will call dev_close() for us. */
2509         if (dev) {
2510                 unregister_netdev(dev);
2511                 free_netdev(dev);
2512         }
2513         cardmap_set(&all_ppp_units, ppp->file.index, NULL);
2514         ppp->file.dead = 1;
2515         ppp->owner = NULL;
2516         wake_up_interruptible(&ppp->file.rwait);
2517         mutex_unlock(&all_ppp_mutex);
2518 }
2519
2520 /*
2521  * Free the memory used by a ppp unit.  This is only called once
2522  * there are no channels connected to the unit and no file structs
2523  * that reference the unit.
2524  */
2525 static void ppp_destroy_interface(struct ppp *ppp)
2526 {
2527         atomic_dec(&ppp_unit_count);
2528
2529         if (!ppp->file.dead || ppp->n_channels) {
2530                 /* "can't happen" */
2531                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2532                        "n_channels=%d !\n", ppp, ppp->file.dead,
2533                        ppp->n_channels);
2534                 return;
2535         }
2536
2537         ppp_ccp_closed(ppp);
2538         if (ppp->vj) {
2539                 slhc_free(ppp->vj);
2540                 ppp->vj = NULL;
2541         }
2542         skb_queue_purge(&ppp->file.xq);
2543         skb_queue_purge(&ppp->file.rq);
2544 #ifdef CONFIG_PPP_MULTILINK
2545         skb_queue_purge(&ppp->mrq);
2546 #endif /* CONFIG_PPP_MULTILINK */
2547 #ifdef CONFIG_PPP_FILTER
2548         kfree(ppp->pass_filter);
2549         ppp->pass_filter = NULL;
2550         kfree(ppp->active_filter);
2551         ppp->active_filter = NULL;
2552 #endif /* CONFIG_PPP_FILTER */
2553
2554         if (ppp->xmit_pending)
2555                 kfree_skb(ppp->xmit_pending);
2556
2557         kfree(ppp);
2558 }
2559
2560 /*
2561  * Locate an existing ppp unit.
2562  * The caller should have locked the all_ppp_mutex.
2563  */
2564 static struct ppp *
2565 ppp_find_unit(int unit)
2566 {
2567         return cardmap_get(all_ppp_units, unit);
2568 }
2569
2570 /*
2571  * Locate an existing ppp channel.
2572  * The caller should have locked the all_channels_lock.
2573  * First we look in the new_channels list, then in the
2574  * all_channels list.  If found in the new_channels list,
2575  * we move it to the all_channels list.  This is for speed
2576  * when we have a lot of channels in use.
2577  */
2578 static struct channel *
2579 ppp_find_channel(int unit)
2580 {
2581         struct channel *pch;
2582
2583         list_for_each_entry(pch, &new_channels, list) {
2584                 if (pch->file.index == unit) {
2585                         list_move(&pch->list, &all_channels);
2586                         return pch;
2587                 }
2588         }
2589         list_for_each_entry(pch, &all_channels, list) {
2590                 if (pch->file.index == unit)
2591                         return pch;
2592         }
2593         return NULL;
2594 }
2595
2596 /*
2597  * Connect a PPP channel to a PPP interface unit.
2598  */
2599 static int
2600 ppp_connect_channel(struct channel *pch, int unit)
2601 {
2602         struct ppp *ppp;
2603         int ret = -ENXIO;
2604         int hdrlen;
2605
2606         mutex_lock(&all_ppp_mutex);
2607         ppp = ppp_find_unit(unit);
2608         if (!ppp)
2609                 goto out;
2610         write_lock_bh(&pch->upl);
2611         ret = -EINVAL;
2612         if (pch->ppp)
2613                 goto outl;
2614
2615         ppp_lock(ppp);
2616         if (pch->file.hdrlen > ppp->file.hdrlen)
2617                 ppp->file.hdrlen = pch->file.hdrlen;
2618         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2619         if (ppp->dev && hdrlen > ppp->dev->hard_header_len)
2620                 ppp->dev->hard_header_len = hdrlen;
2621         list_add_tail(&pch->clist, &ppp->channels);
2622         ++ppp->n_channels;
2623         pch->ppp = ppp;
2624         atomic_inc(&ppp->file.refcnt);
2625         ppp_unlock(ppp);
2626         ret = 0;
2627
2628  outl:
2629         write_unlock_bh(&pch->upl);
2630  out:
2631         mutex_unlock(&all_ppp_mutex);
2632         return ret;
2633 }
2634
2635 /*
2636  * Disconnect a channel from its ppp unit.
2637  */
2638 static int
2639 ppp_disconnect_channel(struct channel *pch)
2640 {
2641         struct ppp *ppp;
2642         int err = -EINVAL;
2643
2644         write_lock_bh(&pch->upl);
2645         ppp = pch->ppp;
2646         pch->ppp = NULL;
2647         write_unlock_bh(&pch->upl);
2648         if (ppp) {
2649                 /* remove it from the ppp unit's list */
2650                 ppp_lock(ppp);
2651                 list_del(&pch->clist);
2652                 if (--ppp->n_channels == 0)
2653                         wake_up_interruptible(&ppp->file.rwait);
2654                 ppp_unlock(ppp);
2655                 if (atomic_dec_and_test(&ppp->file.refcnt))
2656                         ppp_destroy_interface(ppp);
2657                 err = 0;
2658         }
2659         return err;
2660 }
2661
2662 /*
2663  * Free up the resources used by a ppp channel.
2664  */
2665 static void ppp_destroy_channel(struct channel *pch)
2666 {
2667         atomic_dec(&channel_count);
2668
2669         if (!pch->file.dead) {
2670                 /* "can't happen" */
2671                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2672                        pch);
2673                 return;
2674         }
2675         skb_queue_purge(&pch->file.xq);
2676         skb_queue_purge(&pch->file.rq);
2677         kfree(pch);
2678 }
2679
2680 static void __exit ppp_cleanup(void)
2681 {
2682         /* should never happen */
2683         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2684                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2685         cardmap_destroy(&all_ppp_units);
2686         unregister_chrdev(PPP_MAJOR, "ppp");
2687         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2688         class_destroy(ppp_class);
2689 }
2690
2691 /*
2692  * Cardmap implementation.
2693  */
2694 static void *cardmap_get(struct cardmap *map, unsigned int nr)
2695 {
2696         struct cardmap *p;
2697         int i;
2698
2699         for (p = map; p != NULL; ) {
2700                 if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
2701                         return NULL;
2702                 if (p->shift == 0)
2703                         return p->ptr[i];
2704                 nr &= ~(CARDMAP_MASK << p->shift);
2705                 p = p->ptr[i];
2706         }
2707         return NULL;
2708 }
2709
2710 static int cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
2711 {
2712         struct cardmap *p;
2713         int i;
2714
2715         p = *pmap;
2716         if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
2717                 do {
2718                         /* need a new top level */
2719                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2720                         if (!np)
2721                                 goto enomem;
2722                         np->ptr[0] = p;
2723                         if (p != NULL) {
2724                                 np->shift = p->shift + CARDMAP_ORDER;
2725                                 p->parent = np;
2726                         } else
2727                                 np->shift = 0;
2728                         p = np;
2729                 } while ((nr >> p->shift) >= CARDMAP_WIDTH);
2730                 *pmap = p;
2731         }
2732         while (p->shift > 0) {
2733                 i = (nr >> p->shift) & CARDMAP_MASK;
2734                 if (p->ptr[i] == NULL) {
2735                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2736                         if (!np)
2737                                 goto enomem;
2738                         np->shift = p->shift - CARDMAP_ORDER;
2739                         np->parent = p;
2740                         p->ptr[i] = np;
2741                 }
2742                 if (ptr == NULL)
2743                         clear_bit(i, &p->inuse);
2744                 p = p->ptr[i];
2745         }
2746         i = nr & CARDMAP_MASK;
2747         p->ptr[i] = ptr;
2748         if (ptr != NULL)
2749                 set_bit(i, &p->inuse);
2750         else
2751                 clear_bit(i, &p->inuse);
2752         return 0;
2753  enomem:
2754         return -ENOMEM;
2755 }
2756
2757 static unsigned int cardmap_find_first_free(struct cardmap *map)
2758 {
2759         struct cardmap *p;
2760         unsigned int nr = 0;
2761         int i;
2762
2763         if ((p = map) == NULL)
2764                 return 0;
2765         for (;;) {
2766                 i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
2767                 if (i >= CARDMAP_WIDTH) {
2768                         if (p->parent == NULL)
2769                                 return CARDMAP_WIDTH << p->shift;
2770                         p = p->parent;
2771                         i = (nr >> p->shift) & CARDMAP_MASK;
2772                         set_bit(i, &p->inuse);
2773                         continue;
2774                 }
2775                 nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
2776                 if (p->shift == 0 || p->ptr[i] == NULL)
2777                         return nr;
2778                 p = p->ptr[i];
2779         }
2780 }
2781
2782 static void cardmap_destroy(struct cardmap **pmap)
2783 {
2784         struct cardmap *p, *np;
2785         int i;
2786
2787         for (p = *pmap; p != NULL; p = np) {
2788                 if (p->shift != 0) {
2789                         for (i = 0; i < CARDMAP_WIDTH; ++i)
2790                                 if (p->ptr[i] != NULL)
2791                                         break;
2792                         if (i < CARDMAP_WIDTH) {
2793                                 np = p->ptr[i];
2794                                 p->ptr[i] = NULL;
2795                                 continue;
2796                         }
2797                 }
2798                 np = p->parent;
2799                 kfree(p);
2800         }
2801         *pmap = NULL;
2802 }
2803
2804 /* Module/initialization stuff */
2805
2806 module_init(ppp_init);
2807 module_exit(ppp_cleanup);
2808
2809 EXPORT_SYMBOL(ppp_register_channel);
2810 EXPORT_SYMBOL(ppp_unregister_channel);
2811 EXPORT_SYMBOL(ppp_channel_index);
2812 EXPORT_SYMBOL(ppp_unit_number);
2813 EXPORT_SYMBOL(ppp_input);
2814 EXPORT_SYMBOL(ppp_input_error);
2815 EXPORT_SYMBOL(ppp_output_wakeup);
2816 EXPORT_SYMBOL(ppp_register_compressor);
2817 EXPORT_SYMBOL(ppp_unregister_compressor);
2818 MODULE_LICENSE("GPL");
2819 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2820 MODULE_ALIAS("/dev/ppp");