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         int             closing;        /* is device closing down? a8 */
 120 #ifdef CONFIG_PPP_MULTILINK
 121         int             nxchan;         /* next channel to send something on */
 122         u32             nxseq;          /* next sequence number to send */
 123         int             mrru;           /* MP: max reconst. receive unit */
 124         u32             nextseq;        /* MP: seq no of next packet */
 125         u32             minseq;         /* MP: min of most recent seqnos */
 126         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
 127 #endif /* CONFIG_PPP_MULTILINK */
 128 #ifdef CONFIG_PPP_FILTER
 129         struct sock_filter *pass_filter;        /* filter for packets to pass */
 130         struct sock_filter *active_filter;/* filter for pkts to reset idle */
 131         unsigned pass_len, active_len;
 132 #endif /* CONFIG_PPP_FILTER */
 133 };
 134
 135 /*
 136  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
 137  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
 138  * SC_MUST_COMP
 139  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
 140  * Bits in xstate: SC_COMP_RUN
 141  */
 142 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
 143                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
 144                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
 145
 146 /*
 147  * Private data structure for each channel.
 148  * This includes the data structure used for multilink.
 149  */
 150 struct channel {
 151         struct ppp_file file;           /* stuff for read/write/poll */
 152         struct list_head list;          /* link in all/new_channels list */
 153         struct ppp_channel *chan;       /* public channel data structure */
 154         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
 155         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
 156         struct ppp      *ppp;           /* ppp unit we're connected to */
 157         struct list_head clist;         /* link in list of channels per unit */
 158         rwlock_t        upl;            /* protects `ppp' */
 159 #ifdef CONFIG_PPP_MULTILINK
 160         u8              avail;          /* flag used in multilink stuff */
 161         u8              had_frag;       /* >= 1 fragments have been sent */
 162         u32             lastseq;        /* MP: last sequence # received */
 163 #endif /* CONFIG_PPP_MULTILINK */
 164 };
 165
 166 /*
 167  * SMP locking issues:
 168  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
 169  * list and the ppp.n_channels field, you need to take both locks
 170  * before you modify them.
 171  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
 172  * channel.downl.
 173  */
 174
 175 /*
 176  * A cardmap represents a mapping from unsigned integers to pointers,
 177  * and provides a fast "find lowest unused number" operation.
 178  * It uses a broad (32-way) tree with a bitmap at each level.
 179  * It is designed to be space-efficient for small numbers of entries
 180  * and time-efficient for large numbers of entries.
 181  */
 182 #define CARDMAP_ORDER   5
 183 #define CARDMAP_WIDTH   (1U << CARDMAP_ORDER)
 184 #define CARDMAP_MASK    (CARDMAP_WIDTH - 1)
 185
 186 struct cardmap {
 187         int shift;
 188         unsigned long inuse;
 189         struct cardmap *parent;
 190         void *ptr[CARDMAP_WIDTH];
 191 };
 192 static void *cardmap_get(struct cardmap *map, unsigned int nr);
 193 static int cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
 194 static unsigned int cardmap_find_first_free(struct cardmap *map);
 195 static void cardmap_destroy(struct cardmap **map);
 196
 197 /*
 198  * all_ppp_mutex protects the all_ppp_units mapping.
 199  * It also ensures that finding a ppp unit in the all_ppp_units map
 200  * and updating its file.refcnt field is atomic.
 201  */
 202 static DEFINE_MUTEX(all_ppp_mutex);
 203 static struct cardmap *all_ppp_units;
 204 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 205
 206 /*
 207  * all_channels_lock protects all_channels and last_channel_index,
 208  * and the atomicity of find a channel and updating its file.refcnt
 209  * field.
 210  */
 211 static DEFINE_SPINLOCK(all_channels_lock);
 212 static LIST_HEAD(all_channels);
 213 static LIST_HEAD(new_channels);
 214 static int last_channel_index;
 215 static atomic_t channel_count = ATOMIC_INIT(0);
 216
 217 /* Get the PPP protocol number from a skb */
 218 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
 219
 220 /* We limit the length of ppp->file.rq to this (arbitrary) value */
 221 #define PPP_MAX_RQLEN   32
 222
 223 /*
 224  * Maximum number of multilink fragments queued up.
 225  * This has to be large enough to cope with the maximum latency of
 226  * the slowest channel relative to the others.  Strictly it should
 227  * depend on the number of channels and their characteristics.
 228  */
 229 #define PPP_MP_MAX_QLEN 128
 230
 231 /* Multilink header bits. */
 232 #define B       0x80            /* this fragment begins a packet */
 233 #define E       0x40            /* this fragment ends a packet */
 234
 235 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
 236 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
 237 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
 238
 239 /* Prototypes. */
 240 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 241                                 unsigned int cmd, unsigned long arg);
 242 static void ppp_xmit_process(struct ppp *ppp);
 243 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
 244 static void ppp_push(struct ppp *ppp);
 245 static void ppp_channel_push(struct channel *pch);
 246 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
 247                               struct channel *pch);
 248 static void ppp_receive_error(struct ppp *ppp);
 249 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
 250 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
 251                                             struct sk_buff *skb);
 252 #ifdef CONFIG_PPP_MULTILINK
 253 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
 254                                 struct channel *pch);
 255 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
 256 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
 257 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
 258 #endif /* CONFIG_PPP_MULTILINK */
 259 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
 260 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
 261 static void ppp_ccp_closed(struct ppp *ppp);
 262 static struct compressor *find_compressor(int type);
 263 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
 264 static struct ppp *ppp_create_interface(int unit, int *retp);
 265 static void init_ppp_file(struct ppp_file *pf, int kind);
 266 static void ppp_shutdown_interface(struct ppp *ppp);
 267 static void ppp_destroy_interface(struct ppp *ppp);
 268 static struct ppp *ppp_find_unit(int unit);
 269 static struct channel *ppp_find_channel(int unit);
 270 static int ppp_connect_channel(struct channel *pch, int unit);
 271 static int ppp_disconnect_channel(struct channel *pch);
 272 static void ppp_destroy_channel(struct channel *pch);
 273
 274 static struct class *ppp_class;
 275
 276 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
 277 static inline int proto_to_npindex(int proto)
 278 {
 279         switch (proto) {
 280         case PPP_IP:
 281                 return NP_IP;
 282         case PPP_IPV6:
 283                 return NP_IPV6;
 284         case PPP_IPX:
 285                 return NP_IPX;
 286         case PPP_AT:
 287                 return NP_AT;
 288         case PPP_MPLS_UC:
 289                 return NP_MPLS_UC;
 290         case PPP_MPLS_MC:
 291                 return NP_MPLS_MC;
 292         }
 293         return -EINVAL;
 294 }
 295
 296 /* Translates an NP index into a PPP protocol number */
 297 static const int npindex_to_proto[NUM_NP] = {
 298         PPP_IP,
 299         PPP_IPV6,
 300         PPP_IPX,
 301         PPP_AT,
 302         PPP_MPLS_UC,
 303         PPP_MPLS_MC,
 304 };
 305
 306 /* Translates an ethertype into an NP index */
 307 static inline int ethertype_to_npindex(int ethertype)
 308 {
 309         switch (ethertype) {
 310         case ETH_P_IP:
 311                 return NP_IP;
 312         case ETH_P_IPV6:
 313                 return NP_IPV6;
 314         case ETH_P_IPX:
 315                 return NP_IPX;
 316         case ETH_P_PPPTALK:
 317         case ETH_P_ATALK:
 318                 return NP_AT;
 319         case ETH_P_MPLS_UC:
 320                 return NP_MPLS_UC;
 321         case ETH_P_MPLS_MC:
 322                 return NP_MPLS_MC;
 323         }
 324         return -1;
 325 }
 326
 327 /* Translates an NP index into an ethertype */
 328 static const int npindex_to_ethertype[NUM_NP] = {
 329         ETH_P_IP,
 330         ETH_P_IPV6,
 331         ETH_P_IPX,
 332         ETH_P_PPPTALK,
 333         ETH_P_MPLS_UC,
 334         ETH_P_MPLS_MC,
 335 };
 336
 337 /*
 338  * Locking shorthand.
 339  */
 340 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
 341 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
 342 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
 343 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
 344 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
 345                                      ppp_recv_lock(ppp); } while (0)
 346 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
 347                                      ppp_xmit_unlock(ppp); } while (0)
 348
 349 /*
 350  * /dev/ppp device routines.
 351  * The /dev/ppp device is used by pppd to control the ppp unit.
 352  * It supports the read, write, ioctl and poll functions.
 353  * Open instances of /dev/ppp can be in one of three states:
 354  * unattached, attached to a ppp unit, or attached to a ppp channel.
 355  */
 356 static int ppp_open(struct inode *inode, struct file *file)
 357 {
 358         cycle_kernel_lock();
 359         /*
 360          * This could (should?) be enforced by the permissions on /dev/ppp.
 361          */
 362         if (!capable(CAP_NET_ADMIN))
 363                 return -EPERM;
 364         return 0;
 365 }
 366
 367 static int ppp_release(struct inode *unused, struct file *file)
 368 {
 369         struct ppp_file *pf = file->private_data;
 370         struct ppp *ppp;
 371
 372         if (pf) {
 373                 file->private_data = NULL;
 374                 if (pf->kind == INTERFACE) {
 375                         ppp = PF_TO_PPP(pf);
 376                         if (file == ppp->owner)
 377                                 ppp_shutdown_interface(ppp);
 378                 }
 379                 if (atomic_dec_and_test(&pf->refcnt)) {
 380                         switch (pf->kind) {
 381                         case INTERFACE:
 382                                 ppp_destroy_interface(PF_TO_PPP(pf));
 383                                 break;
 384                         case CHANNEL:
 385                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
 386                                 break;
 387                         }
 388                 }
 389         }
 390         return 0;
 391 }
 392
 393 static ssize_t ppp_read(struct file *file, char __user *buf,
 394                         size_t count, loff_t *ppos)
 395 {
 396         struct ppp_file *pf = file->private_data;
 397         DECLARE_WAITQUEUE(wait, current);
 398         ssize_t ret;
 399         struct sk_buff *skb = NULL;
 400
 401         ret = count;
 402
 403         if (!pf)
 404                 return -ENXIO;
 405         add_wait_queue(&pf->rwait, &wait);
 406         for (;;) {
 407                 set_current_state(TASK_INTERRUPTIBLE);
 408                 skb = skb_dequeue(&pf->rq);
 409                 if (skb)
 410                         break;
 411                 ret = 0;
 412                 if (pf->dead)
 413                         break;
 414                 if (pf->kind == INTERFACE) {
 415                         /*
 416                          * Return 0 (EOF) on an interface that has no
 417                          * channels connected, unless it is looping
 418                          * network traffic (demand mode).
 419                          */
 420                         struct ppp *ppp = PF_TO_PPP(pf);
 421                         if (ppp->n_channels == 0
 422                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 423                                 break;
 424                 }
 425                 ret = -EAGAIN;
 426                 if (file->f_flags & O_NONBLOCK)
 427                         break;
 428                 ret = -ERESTARTSYS;
 429                 if (signal_pending(current))
 430                         break;
 431                 schedule();
 432         }
 433         set_current_state(TASK_RUNNING);
 434         remove_wait_queue(&pf->rwait, &wait);
 435
 436         if (!skb)
 437                 goto out;
 438
 439         ret = -EOVERFLOW;
 440         if (skb->len > count)
 441                 goto outf;
 442         ret = -EFAULT;
 443         if (copy_to_user(buf, skb->data, skb->len))
 444                 goto outf;
 445         ret = skb->len;
 446
 447  outf:
 448         kfree_skb(skb);
 449  out:
 450         return ret;
 451 }
 452
 453 static ssize_t ppp_write(struct file *file, const char __user *buf,
 454                          size_t count, loff_t *ppos)
 455 {
 456         struct ppp_file *pf = file->private_data;
 457         struct sk_buff *skb;
 458         ssize_t ret;
 459
 460         if (!pf)
 461                 return -ENXIO;
 462         ret = -ENOMEM;
 463         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
 464         if (!skb)
 465                 goto out;
 466         skb_reserve(skb, pf->hdrlen);
 467         ret = -EFAULT;
 468         if (copy_from_user(skb_put(skb, count), buf, count)) {
 469                 kfree_skb(skb);
 470                 goto out;
 471         }
 472
 473         skb_queue_tail(&pf->xq, skb);
 474
 475         switch (pf->kind) {
 476         case INTERFACE:
 477                 ppp_xmit_process(PF_TO_PPP(pf));
 478                 break;
 479         case CHANNEL:
 480                 ppp_channel_push(PF_TO_CHANNEL(pf));
 481                 break;
 482         }
 483
 484         ret = count;
 485
 486  out:
 487         return ret;
 488 }
 489
 490 /* No kernel lock - fine */
 491 static unsigned int ppp_poll(struct file *file, poll_table *wait)
 492 {
 493         struct ppp_file *pf = file->private_data;
 494         unsigned int mask;
 495
 496         if (!pf)
 497                 return 0;
 498         poll_wait(file, &pf->rwait, wait);
 499         mask = POLLOUT | POLLWRNORM;
 500         if (skb_peek(&pf->rq))
 501                 mask |= POLLIN | POLLRDNORM;
 502         if (pf->dead)
 503                 mask |= POLLHUP;
 504         else if (pf->kind == INTERFACE) {
 505                 /* see comment in ppp_read */
 506                 struct ppp *ppp = PF_TO_PPP(pf);
 507                 if (ppp->n_channels == 0
 508                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 509                         mask |= POLLIN | POLLRDNORM;
 510         }
 511
 512         return mask;
 513 }
 514
 515 #ifdef CONFIG_PPP_FILTER
 516 static int get_filter(void __user *arg, struct sock_filter **p)
 517 {
 518         struct sock_fprog uprog;
 519         struct sock_filter *code = NULL;
 520         int len, err;
 521
 522         if (copy_from_user(&uprog, arg, sizeof(uprog)))
 523                 return -EFAULT;
 524
 525         if (!uprog.len) {
 526                 *p = NULL;
 527                 return 0;
 528         }
 529
 530         len = uprog.len * sizeof(struct sock_filter);
 531         code = kmalloc(len, GFP_KERNEL);
 532         if (code == NULL)
 533                 return -ENOMEM;
 534
 535         if (copy_from_user(code, uprog.filter, len)) {
 536                 kfree(code);
 537                 return -EFAULT;
 538         }
 539
 540         err = sk_chk_filter(code, uprog.len);
 541         if (err) {
 542                 kfree(code);
 543                 return err;
 544         }
 545
 546         *p = code;
 547         return uprog.len;
 548 }
 549 #endif /* CONFIG_PPP_FILTER */
 550
 551 static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 552 {
 553         struct ppp_file *pf = file->private_data;
 554         struct ppp *ppp;
 555         int err = -EFAULT, val, val2, i;
 556         struct ppp_idle idle;
 557         struct npioctl npi;
 558         int unit, cflags;
 559         struct slcompress *vj;
 560         void __user *argp = (void __user *)arg;
 561         int __user *p = argp;
 562
 563         if (!pf)
 564                 return ppp_unattached_ioctl(pf, file, cmd, arg);
 565
 566         if (cmd == PPPIOCDETACH) {
 567                 /*
 568                  * We have to be careful here... if the file descriptor
 569                  * has been dup'd, we could have another process in the
 570                  * middle of a poll using the same file *, so we had
 571                  * better not free the interface data structures -
 572                  * instead we fail the ioctl.  Even in this case, we
 573                  * shut down the interface if we are the owner of it.
 574                  * Actually, we should get rid of PPPIOCDETACH, userland
 575                  * (i.e. pppd) could achieve the same effect by closing
 576                  * this fd and reopening /dev/ppp.
 577                  */
 578                 err = -EINVAL;
 579                 lock_kernel();
 580                 if (pf->kind == INTERFACE) {
 581                         ppp = PF_TO_PPP(pf);
 582                         if (file == ppp->owner)
 583                                 ppp_shutdown_interface(ppp);
 584                 }
 585                 if (atomic_long_read(&file->f_count) <= 2) {
 586                         ppp_release(NULL, file);
 587                         err = 0;
 588                 } else
 589                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%ld\n",
 590                                atomic_long_read(&file->f_count));
 591                 unlock_kernel();
 592                 return err;
 593         }
 594
 595         if (pf->kind == CHANNEL) {
 596                 struct channel *pch;
 597                 struct ppp_channel *chan;
 598
 599                 lock_kernel();
 600                 pch = PF_TO_CHANNEL(pf);
 601
 602                 switch (cmd) {
 603                 case PPPIOCCONNECT:
 604                         if (get_user(unit, p))
 605                                 break;
 606                         err = ppp_connect_channel(pch, unit);
 607                         break;
 608
 609                 case PPPIOCDISCONN:
 610                         err = ppp_disconnect_channel(pch);
 611                         break;
 612
 613                 default:
 614                         down_read(&pch->chan_sem);
 615                         chan = pch->chan;
 616                         err = -ENOTTY;
 617                         if (chan && chan->ops->ioctl)
 618                                 err = chan->ops->ioctl(chan, cmd, arg);
 619                         up_read(&pch->chan_sem);
 620                 }
 621                 unlock_kernel();
 622                 return err;
 623         }
 624
 625         if (pf->kind != INTERFACE) {
 626                 /* can't happen */
 627                 printk(KERN_ERR "PPP: not interface or channel??\n");
 628                 return -EINVAL;
 629         }
 630
 631         lock_kernel();
 632         ppp = PF_TO_PPP(pf);
 633         switch (cmd) {
 634         case PPPIOCSMRU:
 635                 if (get_user(val, p))
 636                         break;
 637                 ppp->mru = val;
 638                 err = 0;
 639                 break;
 640
 641         case PPPIOCSFLAGS:
 642                 if (get_user(val, p))
 643                         break;
 644                 ppp_lock(ppp);
 645                 cflags = ppp->flags & ~val;
 646                 ppp->flags = val & SC_FLAG_BITS;
 647                 ppp_unlock(ppp);
 648                 if (cflags & SC_CCP_OPEN)
 649                         ppp_ccp_closed(ppp);
 650                 err = 0;
 651                 break;
 652
 653         case PPPIOCGFLAGS:
 654                 val = ppp->flags | ppp->xstate | ppp->rstate;
 655                 if (put_user(val, p))
 656                         break;
 657                 err = 0;
 658                 break;
 659
 660         case PPPIOCSCOMPRESS:
 661                 err = ppp_set_compress(ppp, arg);
 662                 break;
 663
 664         case PPPIOCGUNIT:
 665                 if (put_user(ppp->file.index, p))
 666                         break;
 667                 err = 0;
 668                 break;
 669
 670         case PPPIOCSDEBUG:
 671                 if (get_user(val, p))
 672                         break;
 673                 ppp->debug = val;
 674                 err = 0;
 675                 break;
 676
 677         case PPPIOCGDEBUG:
 678                 if (put_user(ppp->debug, p))
 679                         break;
 680                 err = 0;
 681                 break;
 682
 683         case PPPIOCGIDLE:
 684                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 685                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
 686                 if (copy_to_user(argp, &idle, sizeof(idle)))
 687                         break;
 688                 err = 0;
 689                 break;
 690
 691         case PPPIOCSMAXCID:
 692                 if (get_user(val, p))
 693                         break;
 694                 val2 = 15;
 695                 if ((val >> 16) != 0) {
 696                         val2 = val >> 16;
 697                         val &= 0xffff;
 698                 }
 699                 vj = slhc_init(val2+1, val+1);
 700                 if (!vj) {
 701                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
 702                         err = -ENOMEM;
 703                         break;
 704                 }
 705                 ppp_lock(ppp);
 706                 if (ppp->vj)
 707                         slhc_free(ppp->vj);
 708                 ppp->vj = vj;
 709                 ppp_unlock(ppp);
 710                 err = 0;
 711                 break;
 712
 713         case PPPIOCGNPMODE:
 714         case PPPIOCSNPMODE:
 715                 if (copy_from_user(&npi, argp, sizeof(npi)))
 716                         break;
 717                 err = proto_to_npindex(npi.protocol);
 718                 if (err < 0)
 719                         break;
 720                 i = err;
 721                 if (cmd == PPPIOCGNPMODE) {
 722                         err = -EFAULT;
 723                         npi.mode = ppp->npmode[i];
 724                         if (copy_to_user(argp, &npi, sizeof(npi)))
 725                                 break;
 726                 } else {
 727                         ppp->npmode[i] = npi.mode;
 728                         /* we may be able to transmit more packets now (??) */
 729                         netif_wake_queue(ppp->dev);
 730                 }
 731                 err = 0;
 732                 break;
 733
 734 #ifdef CONFIG_PPP_FILTER
 735         case PPPIOCSPASS:
 736         {
 737                 struct sock_filter *code;
 738                 err = get_filter(argp, &code);
 739                 if (err >= 0) {
 740                         ppp_lock(ppp);
 741                         kfree(ppp->pass_filter);
 742                         ppp->pass_filter = code;
 743                         ppp->pass_len = err;
 744                         ppp_unlock(ppp);
 745                         err = 0;
 746                 }
 747                 break;
 748         }
 749         case PPPIOCSACTIVE:
 750         {
 751                 struct sock_filter *code;
 752                 err = get_filter(argp, &code);
 753                 if (err >= 0) {
 754                         ppp_lock(ppp);
 755                         kfree(ppp->active_filter);
 756                         ppp->active_filter = code;
 757                         ppp->active_len = err;
 758                         ppp_unlock(ppp);
 759                         err = 0;
 760                 }
 761                 break;
 762         }
 763 #endif /* CONFIG_PPP_FILTER */
 764
 765 #ifdef CONFIG_PPP_MULTILINK
 766         case PPPIOCSMRRU:
 767                 if (get_user(val, p))
 768                         break;
 769                 ppp_recv_lock(ppp);
 770                 ppp->mrru = val;
 771                 ppp_recv_unlock(ppp);
 772                 err = 0;
 773                 break;
 774 #endif /* CONFIG_PPP_MULTILINK */
 775
 776         default:
 777                 err = -ENOTTY;
 778         }
 779         unlock_kernel();
 780         return err;
 781 }
 782
 783 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 784                                 unsigned int cmd, unsigned long arg)
 785 {
 786         int unit, err = -EFAULT;
 787         struct ppp *ppp;
 788         struct channel *chan;
 789         int __user *p = (int __user *)arg;
 790
 791         lock_kernel();
 792         switch (cmd) {
 793         case PPPIOCNEWUNIT:
 794                 /* Create a new ppp unit */
 795                 if (get_user(unit, p))
 796                         break;
 797                 ppp = ppp_create_interface(unit, &err);
 798                 if (!ppp)
 799                         break;
 800                 file->private_data = &ppp->file;
 801                 ppp->owner = file;
 802                 err = -EFAULT;
 803                 if (put_user(ppp->file.index, p))
 804                         break;
 805                 err = 0;
 806                 break;
 807
 808         case PPPIOCATTACH:
 809                 /* Attach to an existing ppp unit */
 810                 if (get_user(unit, p))
 811                         break;
 812                 mutex_lock(&all_ppp_mutex);
 813                 err = -ENXIO;
 814                 ppp = ppp_find_unit(unit);
 815                 if (ppp) {
 816                         atomic_inc(&ppp->file.refcnt);
 817                         file->private_data = &ppp->file;
 818                         err = 0;
 819                 }
 820                 mutex_unlock(&all_ppp_mutex);
 821                 break;
 822
 823         case PPPIOCATTCHAN:
 824                 if (get_user(unit, p))
 825                         break;
 826                 spin_lock_bh(&all_channels_lock);
 827                 err = -ENXIO;
 828                 chan = ppp_find_channel(unit);
 829                 if (chan) {
 830                         atomic_inc(&chan->file.refcnt);
 831                         file->private_data = &chan->file;
 832                         err = 0;
 833                 }
 834                 spin_unlock_bh(&all_channels_lock);
 835                 break;
 836
 837         default:
 838                 err = -ENOTTY;
 839         }
 840         unlock_kernel();
 841         return err;
 842 }
 843
 844 static const struct file_operations ppp_device_fops = {
 845         .owner          = THIS_MODULE,
 846         .read           = ppp_read,
 847         .write          = ppp_write,
 848         .poll           = ppp_poll,
 849         .unlocked_ioctl = ppp_ioctl,
 850         .open           = ppp_open,
 851         .release        = ppp_release
 852 };
 853
 854 #define PPP_MAJOR       108
 855
 856 /* Called at boot time if ppp is compiled into the kernel,
 857    or at module load time (from init_module) if compiled as a module. */
 858 static int __init ppp_init(void)
 859 {
 860         int err;
 861
 862         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
 863         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
 864         if (!err) {
 865                 ppp_class = class_create(THIS_MODULE, "ppp");
 866                 if (IS_ERR(ppp_class)) {
 867                         err = PTR_ERR(ppp_class);
 868                         goto out_chrdev;
 869                 }
 870                 device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL,
 871                               "ppp");
 872         }
 873
 874 out:
 875         if (err)
 876                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
 877         return err;
 878
 879 out_chrdev:
 880         unregister_chrdev(PPP_MAJOR, "ppp");
 881         goto out;
 882 }
 883
 884 /*
 885  * Network interface unit routines.
 886  */
 887 static int
 888 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 889 {
 890         struct ppp *ppp = (struct ppp *) dev->priv;
 891         int npi, proto;
 892         unsigned char *pp;
 893
 894         npi = ethertype_to_npindex(ntohs(skb->protocol));
 895         if (npi < 0)
 896                 goto outf;
 897
 898         /* Drop, accept or reject the packet */
 899         switch (ppp->npmode[npi]) {
 900         case NPMODE_PASS:
 901                 break;
 902         case NPMODE_QUEUE:
 903                 /* it would be nice to have a way to tell the network
 904                    system to queue this one up for later. */
 905                 goto outf;
 906         case NPMODE_DROP:
 907         case NPMODE_ERROR:
 908                 goto outf;
 909         }
 910
 911         /* Put the 2-byte PPP protocol number on the front,
 912            making sure there is room for the address and control fields. */
 913         if (skb_cow_head(skb, PPP_HDRLEN))
 914                 goto outf;
 915
 916         pp = skb_push(skb, 2);
 917         proto = npindex_to_proto[npi];
 918         pp[0] = proto >> 8;
 919         pp[1] = proto;
 920
 921         netif_stop_queue(dev);
 922         skb_queue_tail(&ppp->file.xq, skb);
 923         ppp_xmit_process(ppp);
 924         return 0;
 925
 926  outf:
 927         kfree_skb(skb);
 928         ++ppp->dev->stats.tx_dropped;
 929         return 0;
 930 }
 931
 932 static int
 933 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 934 {
 935         struct ppp *ppp = dev->priv;
 936         int err = -EFAULT;
 937         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
 938         struct ppp_stats stats;
 939         struct ppp_comp_stats cstats;
 940         char *vers;
 941
 942         switch (cmd) {
 943         case SIOCGPPPSTATS:
 944                 ppp_get_stats(ppp, &stats);
 945                 if (copy_to_user(addr, &stats, sizeof(stats)))
 946                         break;
 947                 err = 0;
 948                 break;
 949
 950         case SIOCGPPPCSTATS:
 951                 memset(&cstats, 0, sizeof(cstats));
 952                 if (ppp->xc_state)
 953                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
 954                 if (ppp->rc_state)
 955                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
 956                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
 957                         break;
 958                 err = 0;
 959                 break;
 960
 961         case SIOCGPPPVER:
 962                 vers = PPP_VERSION;
 963                 if (copy_to_user(addr, vers, strlen(vers) + 1))
 964                         break;
 965                 err = 0;
 966                 break;
 967
 968         default:
 969                 err = -EINVAL;
 970         }
 971
 972         return err;
 973 }
 974
 975 static void ppp_setup(struct net_device *dev)
 976 {
 977         dev->hard_header_len = PPP_HDRLEN;
 978         dev->mtu = PPP_MTU;
 979         dev->addr_len = 0;
 980         dev->tx_queue_len = 3;
 981         dev->type = ARPHRD_PPP;
 982         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
 983 }
 984
 985 /*
 986  * Transmit-side routines.
 987  */
 988
 989 /*
 990  * Called to do any work queued up on the transmit side
 991  * that can now be done.
 992  */
 993 static void
 994 ppp_xmit_process(struct ppp *ppp)
 995 {
 996         struct sk_buff *skb;
 997
 998         ppp_xmit_lock(ppp);
 999         if (!ppp->closing) {
1000                 ppp_push(ppp);
1001                 while (!ppp->xmit_pending
1002                        && (skb = skb_dequeue(&ppp->file.xq)))
1003                         ppp_send_frame(ppp, skb);
1004                 /* If there's no work left to do, tell the core net
1005                    code that we can accept some more. */
1006                 if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
1007                         netif_wake_queue(ppp->dev);
1008         }
1009         ppp_xmit_unlock(ppp);
1010 }
1011
1012 static inline struct sk_buff *
1013 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1014 {
1015         struct sk_buff *new_skb;
1016         int len;
1017         int new_skb_size = ppp->dev->mtu +
1018                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1019         int compressor_skb_size = ppp->dev->mtu +
1020                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1021         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1022         if (!new_skb) {
1023                 if (net_ratelimit())
1024                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1025                 return NULL;
1026         }
1027         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1028                 skb_reserve(new_skb,
1029                             ppp->dev->hard_header_len - PPP_HDRLEN);
1030
1031         /* compressor still expects A/C bytes in hdr */
1032         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1033                                    new_skb->data, skb->len + 2,
1034                                    compressor_skb_size);
1035         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1036                 kfree_skb(skb);
1037                 skb = new_skb;
1038                 skb_put(skb, len);
1039                 skb_pull(skb, 2);       /* pull off A/C bytes */
1040         } else if (len == 0) {
1041                 /* didn't compress, or CCP not up yet */
1042                 kfree_skb(new_skb);
1043                 new_skb = skb;
1044         } else {
1045                 /*
1046                  * (len < 0)
1047                  * MPPE requires that we do not send unencrypted
1048                  * frames.  The compressor will return -1 if we
1049                  * should drop the frame.  We cannot simply test
1050                  * the compress_proto because MPPE and MPPC share
1051                  * the same number.
1052                  */
1053                 if (net_ratelimit())
1054                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1055                 kfree_skb(skb);
1056                 kfree_skb(new_skb);
1057                 new_skb = NULL;
1058         }
1059         return new_skb;
1060 }
1061
1062 /*
1063  * Compress and send a frame.
1064  * The caller should have locked the xmit path,
1065  * and xmit_pending should be 0.
1066  */
1067 static void
1068 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1069 {
1070         int proto = PPP_PROTO(skb);
1071         struct sk_buff *new_skb;
1072         int len;
1073         unsigned char *cp;
1074
1075         if (proto < 0x8000) {
1076 #ifdef CONFIG_PPP_FILTER
1077                 /* check if we should pass this packet */
1078                 /* the filter instructions are constructed assuming
1079                    a four-byte PPP header on each packet */
1080                 *skb_push(skb, 2) = 1;
1081                 if (ppp->pass_filter
1082                     && sk_run_filter(skb, ppp->pass_filter,
1083                                      ppp->pass_len) == 0) {
1084                         if (ppp->debug & 1)
1085                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1086                         kfree_skb(skb);
1087                         return;
1088                 }
1089                 /* if this packet passes the active filter, record the time */
1090                 if (!(ppp->active_filter
1091                       && sk_run_filter(skb, ppp->active_filter,
1092                                        ppp->active_len) == 0))
1093                         ppp->last_xmit = jiffies;
1094                 skb_pull(skb, 2);
1095 #else
1096                 /* for data packets, record the time */
1097                 ppp->last_xmit = jiffies;
1098 #endif /* CONFIG_PPP_FILTER */
1099         }
1100
1101         ++ppp->dev->stats.tx_packets;
1102         ppp->dev->stats.tx_bytes += skb->len - 2;
1103
1104         switch (proto) {
1105         case PPP_IP:
1106                 if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1107                         break;
1108                 /* try to do VJ TCP header compression */
1109                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1110                                     GFP_ATOMIC);
1111                 if (!new_skb) {
1112                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1113                         goto drop;
1114                 }
1115                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1116                 cp = skb->data + 2;
1117                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1118                                     new_skb->data + 2, &cp,
1119                                     !(ppp->flags & SC_NO_TCP_CCID));
1120                 if (cp == skb->data + 2) {
1121                         /* didn't compress */
1122                         kfree_skb(new_skb);
1123                 } else {
1124                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1125                                 proto = PPP_VJC_COMP;
1126                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1127                         } else {
1128                                 proto = PPP_VJC_UNCOMP;
1129                                 cp[0] = skb->data[2];
1130                         }
1131                         kfree_skb(skb);
1132                         skb = new_skb;
1133                         cp = skb_put(skb, len + 2);
1134                         cp[0] = 0;
1135                         cp[1] = proto;
1136                 }
1137                 break;
1138
1139         case PPP_CCP:
1140                 /* peek at outbound CCP frames */
1141                 ppp_ccp_peek(ppp, skb, 0);
1142                 break;
1143         }
1144
1145         /* try to do packet compression */
1146         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state
1147             && proto != PPP_LCP && proto != PPP_CCP) {
1148                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1149                         if (net_ratelimit())
1150                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1151                         goto drop;
1152                 }
1153                 skb = pad_compress_skb(ppp, skb);
1154                 if (!skb)
1155                         goto drop;
1156         }
1157
1158         /*
1159          * If we are waiting for traffic (demand dialling),
1160          * queue it up for pppd to receive.
1161          */
1162         if (ppp->flags & SC_LOOP_TRAFFIC) {
1163                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1164                         goto drop;
1165                 skb_queue_tail(&ppp->file.rq, skb);
1166                 wake_up_interruptible(&ppp->file.rwait);
1167                 return;
1168         }
1169
1170         ppp->xmit_pending = skb;
1171         ppp_push(ppp);
1172         return;
1173
1174  drop:
1175         if (skb)
1176                 kfree_skb(skb);
1177         ++ppp->dev->stats.tx_errors;
1178 }
1179
1180 /*
1181  * Try to send the frame in xmit_pending.
1182  * The caller should have the xmit path locked.
1183  */
1184 static void
1185 ppp_push(struct ppp *ppp)
1186 {
1187         struct list_head *list;
1188         struct channel *pch;
1189         struct sk_buff *skb = ppp->xmit_pending;
1190
1191         if (!skb)
1192                 return;
1193
1194         list = &ppp->channels;
1195         if (list_empty(list)) {
1196                 /* nowhere to send the packet, just drop it */
1197                 ppp->xmit_pending = NULL;
1198                 kfree_skb(skb);
1199                 return;
1200         }
1201
1202         if ((ppp->flags & SC_MULTILINK) == 0) {
1203                 /* not doing multilink: send it down the first channel */
1204                 list = list->next;
1205                 pch = list_entry(list, struct channel, clist);
1206
1207                 spin_lock_bh(&pch->downl);
1208                 if (pch->chan) {
1209                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1210                                 ppp->xmit_pending = NULL;
1211                 } else {
1212                         /* channel got unregistered */
1213                         kfree_skb(skb);
1214                         ppp->xmit_pending = NULL;
1215                 }
1216                 spin_unlock_bh(&pch->downl);
1217                 return;
1218         }
1219
1220 #ifdef CONFIG_PPP_MULTILINK
1221         /* Multilink: fragment the packet over as many links
1222            as can take the packet at the moment. */
1223         if (!ppp_mp_explode(ppp, skb))
1224                 return;
1225 #endif /* CONFIG_PPP_MULTILINK */
1226
1227         ppp->xmit_pending = NULL;
1228         kfree_skb(skb);
1229 }
1230
1231 #ifdef CONFIG_PPP_MULTILINK
1232 /*
1233  * Divide a packet to be transmitted into fragments and
1234  * send them out the individual links.
1235  */
1236 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1237 {
1238         int len, fragsize;
1239         int i, bits, hdrlen, mtu;
1240         int flen;
1241         int navail, nfree;
1242         int nbigger;
1243         unsigned char *p, *q;
1244         struct list_head *list;
1245         struct channel *pch;
1246         struct sk_buff *frag;
1247         struct ppp_channel *chan;
1248
1249         nfree = 0;      /* # channels which have no packet already queued */
1250         navail = 0;     /* total # of usable channels (not deregistered) */
1251         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1252         i = 0;
1253         list_for_each_entry(pch, &ppp->channels, clist) {
1254                 navail += pch->avail = (pch->chan != NULL);
1255                 if (pch->avail) {
1256                         if (skb_queue_empty(&pch->file.xq) ||
1257                             !pch->had_frag) {
1258                                 pch->avail = 2;
1259                                 ++nfree;
1260                         }
1261                         if (!pch->had_frag && i < ppp->nxchan)
1262                                 ppp->nxchan = i;
1263                 }
1264                 ++i;
1265         }
1266
1267         /*
1268          * Don't start sending this packet unless at least half of
1269          * the channels are free.  This gives much better TCP
1270          * performance if we have a lot of channels.
1271          */
1272         if (nfree == 0 || nfree < navail / 2)
1273                 return 0;       /* can't take now, leave it in xmit_pending */
1274
1275         /* Do protocol field compression (XXX this should be optional) */
1276         p = skb->data;
1277         len = skb->len;
1278         if (*p == 0) {
1279                 ++p;
1280                 --len;
1281         }
1282
1283         /*
1284          * Decide on fragment size.
1285          * We create a fragment for each free channel regardless of
1286          * how small they are (i.e. even 0 length) in order to minimize
1287          * the time that it will take to detect when a channel drops
1288          * a fragment.
1289          */
1290         fragsize = len;
1291         if (nfree > 1)
1292                 fragsize = DIV_ROUND_UP(fragsize, nfree);
1293         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1294            except if nbigger==0, then they all get fragsize. */
1295         nbigger = len % nfree;
1296
1297         /* skip to the channel after the one we last used
1298            and start at that one */
1299         list = &ppp->channels;
1300         for (i = 0; i < ppp->nxchan; ++i) {
1301                 list = list->next;
1302                 if (list == &ppp->channels) {
1303                         i = 0;
1304                         break;
1305                 }
1306         }
1307
1308         /* create a fragment for each channel */
1309         bits = B;
1310         while (nfree > 0 || len > 0) {
1311                 list = list->next;
1312                 if (list == &ppp->channels) {
1313                         i = 0;
1314                         continue;
1315                 }
1316                 pch = list_entry(list, struct channel, clist);
1317                 ++i;
1318                 if (!pch->avail)
1319                         continue;
1320
1321                 /*
1322                  * Skip this channel if it has a fragment pending already and
1323                  * we haven't given a fragment to all of the free channels.
1324                  */
1325                 if (pch->avail == 1) {
1326                         if (nfree > 0)
1327                                 continue;
1328                 } else {
1329                         --nfree;
1330                         pch->avail = 1;
1331                 }
1332
1333                 /* check the channel's mtu and whether it is still attached. */
1334                 spin_lock_bh(&pch->downl);
1335                 if (pch->chan == NULL) {
1336                         /* can't use this channel, it's being deregistered */
1337                         spin_unlock_bh(&pch->downl);
1338                         pch->avail = 0;
1339                         if (--navail == 0)
1340                                 break;
1341                         continue;
1342                 }
1343
1344                 /*
1345                  * Create a fragment for this channel of
1346                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1347                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1348                  * MTU, so we use mtu = 2 + hdrlen.
1349                  */
1350                 if (fragsize > len)
1351                         fragsize = len;
1352                 flen = fragsize;
1353                 mtu = pch->chan->mtu + 2 - hdrlen;
1354                 if (mtu < 4)
1355                         mtu = 4;
1356                 if (flen > mtu)
1357                         flen = mtu;
1358                 if (flen == len && nfree == 0)
1359                         bits |= E;
1360                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1361                 if (!frag)
1362                         goto noskb;
1363                 q = skb_put(frag, flen + hdrlen);
1364
1365                 /* make the MP header */
1366                 q[0] = PPP_MP >> 8;
1367                 q[1] = PPP_MP;
1368                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1369                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1370                         q[3] = ppp->nxseq;
1371                 } else {
1372                         q[2] = bits;
1373                         q[3] = ppp->nxseq >> 16;
1374                         q[4] = ppp->nxseq >> 8;
1375                         q[5] = ppp->nxseq;
1376                 }
1377
1378                 /*
1379                  * Copy the data in.
1380                  * Unfortunately there is a bug in older versions of
1381                  * the Linux PPP multilink reconstruction code where it
1382                  * drops 0-length fragments.  Therefore we make sure the
1383                  * fragment has at least one byte of data.  Any bytes
1384                  * we add in this situation will end up as padding on the
1385                  * end of the reconstructed packet.
1386                  */
1387                 if (flen == 0)
1388                         *skb_put(frag, 1) = 0;
1389                 else
1390                         memcpy(q + hdrlen, p, flen);
1391
1392                 /* try to send it down the channel */
1393                 chan = pch->chan;
1394                 if (!skb_queue_empty(&pch->file.xq) ||
1395                     !chan->ops->start_xmit(chan, frag))
1396                         skb_queue_tail(&pch->file.xq, frag);
1397                 pch->had_frag = 1;
1398                 p += flen;
1399                 len -= flen;
1400                 ++ppp->nxseq;
1401                 bits = 0;
1402                 spin_unlock_bh(&pch->downl);
1403
1404                 if (--nbigger == 0 && fragsize > 0)
1405                         --fragsize;
1406         }
1407         ppp->nxchan = i;
1408
1409         return 1;
1410
1411  noskb:
1412         spin_unlock_bh(&pch->downl);
1413         if (ppp->debug & 1)
1414                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1415         ++ppp->dev->stats.tx_errors;
1416         ++ppp->nxseq;
1417         return 1;       /* abandon the frame */
1418 }
1419 #endif /* CONFIG_PPP_MULTILINK */
1420
1421 /*
1422  * Try to send data out on a channel.
1423  */
1424 static void
1425 ppp_channel_push(struct channel *pch)
1426 {
1427         struct sk_buff *skb;
1428         struct ppp *ppp;
1429
1430         spin_lock_bh(&pch->downl);
1431         if (pch->chan) {
1432                 while (!skb_queue_empty(&pch->file.xq)) {
1433                         skb = skb_dequeue(&pch->file.xq);
1434                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1435                                 /* put the packet back and try again later */
1436                                 skb_queue_head(&pch->file.xq, skb);
1437                                 break;
1438                         }
1439                 }
1440         } else {
1441                 /* channel got deregistered */
1442                 skb_queue_purge(&pch->file.xq);
1443         }
1444         spin_unlock_bh(&pch->downl);
1445         /* see if there is anything from the attached unit to be sent */
1446         if (skb_queue_empty(&pch->file.xq)) {
1447                 read_lock_bh(&pch->upl);
1448                 ppp = pch->ppp;
1449                 if (ppp)
1450                         ppp_xmit_process(ppp);
1451                 read_unlock_bh(&pch->upl);
1452         }
1453 }
1454
1455 /*
1456  * Receive-side routines.
1457  */
1458
1459 /* misuse a few fields of the skb for MP reconstruction */
1460 #define sequence        priority
1461 #define BEbits          cb[0]
1462
1463 static inline void
1464 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1465 {
1466         ppp_recv_lock(ppp);
1467         if (!ppp->closing)
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         mutex_lock(&all_ppp_mutex);
2502         /* This will call dev_close() for us. */
2503         ppp_lock(ppp);
2504         if (!ppp->closing) {
2505                 ppp->closing = 1;
2506                 ppp_unlock(ppp);
2507                 unregister_netdev(ppp->dev);
2508         } else
2509                 ppp_unlock(ppp);
2510
2511         cardmap_set(&all_ppp_units, ppp->file.index, NULL);
2512         ppp->file.dead = 1;
2513         ppp->owner = NULL;
2514         wake_up_interruptible(&ppp->file.rwait);
2515         mutex_unlock(&all_ppp_mutex);
2516 }
2517
2518 /*
2519  * Free the memory used by a ppp unit.  This is only called once
2520  * there are no channels connected to the unit and no file structs
2521  * that reference the unit.
2522  */
2523 static void ppp_destroy_interface(struct ppp *ppp)
2524 {
2525         atomic_dec(&ppp_unit_count);
2526
2527         if (!ppp->file.dead || ppp->n_channels) {
2528                 /* "can't happen" */
2529                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2530                        "n_channels=%d !\n", ppp, ppp->file.dead,
2531                        ppp->n_channels);
2532                 return;
2533         }
2534
2535         ppp_ccp_closed(ppp);
2536         if (ppp->vj) {
2537                 slhc_free(ppp->vj);
2538                 ppp->vj = NULL;
2539         }
2540         skb_queue_purge(&ppp->file.xq);
2541         skb_queue_purge(&ppp->file.rq);
2542 #ifdef CONFIG_PPP_MULTILINK
2543         skb_queue_purge(&ppp->mrq);
2544 #endif /* CONFIG_PPP_MULTILINK */
2545 #ifdef CONFIG_PPP_FILTER
2546         kfree(ppp->pass_filter);
2547         ppp->pass_filter = NULL;
2548         kfree(ppp->active_filter);
2549         ppp->active_filter = NULL;
2550 #endif /* CONFIG_PPP_FILTER */
2551
2552         if (ppp->xmit_pending)
2553                 kfree_skb(ppp->xmit_pending);
2554
2555         free_netdev(ppp->dev);
2556 }
2557
2558 /*
2559  * Locate an existing ppp unit.
2560  * The caller should have locked the all_ppp_mutex.
2561  */
2562 static struct ppp *
2563 ppp_find_unit(int unit)
2564 {
2565         return cardmap_get(all_ppp_units, unit);
2566 }
2567
2568 /*
2569  * Locate an existing ppp channel.
2570  * The caller should have locked the all_channels_lock.
2571  * First we look in the new_channels list, then in the
2572  * all_channels list.  If found in the new_channels list,
2573  * we move it to the all_channels list.  This is for speed
2574  * when we have a lot of channels in use.
2575  */
2576 static struct channel *
2577 ppp_find_channel(int unit)
2578 {
2579         struct channel *pch;
2580
2581         list_for_each_entry(pch, &new_channels, list) {
2582                 if (pch->file.index == unit) {
2583                         list_move(&pch->list, &all_channels);
2584                         return pch;
2585                 }
2586         }
2587         list_for_each_entry(pch, &all_channels, list) {
2588                 if (pch->file.index == unit)
2589                         return pch;
2590         }
2591         return NULL;
2592 }
2593
2594 /*
2595  * Connect a PPP channel to a PPP interface unit.
2596  */
2597 static int
2598 ppp_connect_channel(struct channel *pch, int unit)
2599 {
2600         struct ppp *ppp;
2601         int ret = -ENXIO;
2602         int hdrlen;
2603
2604         mutex_lock(&all_ppp_mutex);
2605         ppp = ppp_find_unit(unit);
2606         if (!ppp)
2607                 goto out;
2608         write_lock_bh(&pch->upl);
2609         ret = -EINVAL;
2610         if (pch->ppp)
2611                 goto outl;
2612
2613         ppp_lock(ppp);
2614         if (pch->file.hdrlen > ppp->file.hdrlen)
2615                 ppp->file.hdrlen = pch->file.hdrlen;
2616         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2617         if (hdrlen > ppp->dev->hard_header_len)
2618                 ppp->dev->hard_header_len = hdrlen;
2619         list_add_tail(&pch->clist, &ppp->channels);
2620         ++ppp->n_channels;
2621         pch->ppp = ppp;
2622         atomic_inc(&ppp->file.refcnt);
2623         ppp_unlock(ppp);
2624         ret = 0;
2625
2626  outl:
2627         write_unlock_bh(&pch->upl);
2628  out:
2629         mutex_unlock(&all_ppp_mutex);
2630         return ret;
2631 }
2632
2633 /*
2634  * Disconnect a channel from its ppp unit.
2635  */
2636 static int
2637 ppp_disconnect_channel(struct channel *pch)
2638 {
2639         struct ppp *ppp;
2640         int err = -EINVAL;
2641
2642         write_lock_bh(&pch->upl);
2643         ppp = pch->ppp;
2644         pch->ppp = NULL;
2645         write_unlock_bh(&pch->upl);
2646         if (ppp) {
2647                 /* remove it from the ppp unit's list */
2648                 ppp_lock(ppp);
2649                 list_del(&pch->clist);
2650                 if (--ppp->n_channels == 0)
2651                         wake_up_interruptible(&ppp->file.rwait);
2652                 ppp_unlock(ppp);
2653                 if (atomic_dec_and_test(&ppp->file.refcnt))
2654                         ppp_destroy_interface(ppp);
2655                 err = 0;
2656         }
2657         return err;
2658 }
2659
2660 /*
2661  * Free up the resources used by a ppp channel.
2662  */
2663 static void ppp_destroy_channel(struct channel *pch)
2664 {
2665         atomic_dec(&channel_count);
2666
2667         if (!pch->file.dead) {
2668                 /* "can't happen" */
2669                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2670                        pch);
2671                 return;
2672         }
2673         skb_queue_purge(&pch->file.xq);
2674         skb_queue_purge(&pch->file.rq);
2675         kfree(pch);
2676 }
2677
2678 static void __exit ppp_cleanup(void)
2679 {
2680         /* should never happen */
2681         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2682                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2683         cardmap_destroy(&all_ppp_units);
2684         unregister_chrdev(PPP_MAJOR, "ppp");
2685         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2686         class_destroy(ppp_class);
2687 }
2688
2689 /*
2690  * Cardmap implementation.
2691  */
2692 static void *cardmap_get(struct cardmap *map, unsigned int nr)
2693 {
2694         struct cardmap *p;
2695         int i;
2696
2697         for (p = map; p != NULL; ) {
2698                 if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
2699                         return NULL;
2700                 if (p->shift == 0)
2701                         return p->ptr[i];
2702                 nr &= ~(CARDMAP_MASK << p->shift);
2703                 p = p->ptr[i];
2704         }
2705         return NULL;
2706 }
2707
2708 static int cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
2709 {
2710         struct cardmap *p;
2711         int i;
2712
2713         p = *pmap;
2714         if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
2715                 do {
2716                         /* need a new top level */
2717                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2718                         if (!np)
2719                                 goto enomem;
2720                         np->ptr[0] = p;
2721                         if (p != NULL) {
2722                                 np->shift = p->shift + CARDMAP_ORDER;
2723                                 p->parent = np;
2724                         } else
2725                                 np->shift = 0;
2726                         p = np;
2727                 } while ((nr >> p->shift) >= CARDMAP_WIDTH);
2728                 *pmap = p;
2729         }
2730         while (p->shift > 0) {
2731                 i = (nr >> p->shift) & CARDMAP_MASK;
2732                 if (p->ptr[i] == NULL) {
2733                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2734                         if (!np)
2735                                 goto enomem;
2736                         np->shift = p->shift - CARDMAP_ORDER;
2737                         np->parent = p;
2738                         p->ptr[i] = np;
2739                 }
2740                 if (ptr == NULL)
2741                         clear_bit(i, &p->inuse);
2742                 p = p->ptr[i];
2743         }
2744         i = nr & CARDMAP_MASK;
2745         p->ptr[i] = ptr;
2746         if (ptr != NULL)
2747                 set_bit(i, &p->inuse);
2748         else
2749                 clear_bit(i, &p->inuse);
2750         return 0;
2751  enomem:
2752         return -ENOMEM;
2753 }
2754
2755 static unsigned int cardmap_find_first_free(struct cardmap *map)
2756 {
2757         struct cardmap *p;
2758         unsigned int nr = 0;
2759         int i;
2760
2761         if ((p = map) == NULL)
2762                 return 0;
2763         for (;;) {
2764                 i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
2765                 if (i >= CARDMAP_WIDTH) {
2766                         if (p->parent == NULL)
2767                                 return CARDMAP_WIDTH << p->shift;
2768                         p = p->parent;
2769                         i = (nr >> p->shift) & CARDMAP_MASK;
2770                         set_bit(i, &p->inuse);
2771                         continue;
2772                 }
2773                 nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
2774                 if (p->shift == 0 || p->ptr[i] == NULL)
2775                         return nr;
2776                 p = p->ptr[i];
2777         }
2778 }
2779
2780 static void cardmap_destroy(struct cardmap **pmap)
2781 {
2782         struct cardmap *p, *np;
2783         int i;
2784
2785         for (p = *pmap; p != NULL; p = np) {
2786                 if (p->shift != 0) {
2787                         for (i = 0; i < CARDMAP_WIDTH; ++i)
2788                                 if (p->ptr[i] != NULL)
2789                                         break;
2790                         if (i < CARDMAP_WIDTH) {
2791                                 np = p->ptr[i];
2792                                 p->ptr[i] = NULL;
2793                                 continue;
2794                         }
2795                 }
2796                 np = p->parent;
2797                 kfree(p);
2798         }
2799         *pmap = NULL;
2800 }
2801
2802 /* Module/initialization stuff */
2803
2804 module_init(ppp_init);
2805 module_exit(ppp_cleanup);
2806
2807 EXPORT_SYMBOL(ppp_register_channel);
2808 EXPORT_SYMBOL(ppp_unregister_channel);
2809 EXPORT_SYMBOL(ppp_channel_index);
2810 EXPORT_SYMBOL(ppp_unit_number);
2811 EXPORT_SYMBOL(ppp_input);
2812 EXPORT_SYMBOL(ppp_input_error);
2813 EXPORT_SYMBOL(ppp_output_wakeup);
2814 EXPORT_SYMBOL(ppp_register_compressor);
2815 EXPORT_SYMBOL(ppp_unregister_compressor);
2816 MODULE_LICENSE("GPL");
2817 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2818 MODULE_ALIAS("/dev/ppp");