drivers/net/ppp_generic.c

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