drivers/net/ppp_generic.c

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