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         struct net_device_stats stats;  /* statistics */
 127 #ifdef CONFIG_PPP_FILTER
 128         struct sock_filter *pass_filter;        /* filter for packets to pass */
 129         struct sock_filter *active_filter;/* filter for pkts to reset idle */
 130         unsigned pass_len, active_len;
 131 #endif /* CONFIG_PPP_FILTER */
 132 };
 133
 134 /*
 135  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
 136  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
 137  * SC_MUST_COMP
 138  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
 139  * Bits in xstate: SC_COMP_RUN
 140  */
 141 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
 142                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
 143                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
 144
 145 /*
 146  * Private data structure for each channel.
 147  * This includes the data structure used for multilink.
 148  */
 149 struct channel {
 150         struct ppp_file file;           /* stuff for read/write/poll */
 151         struct list_head list;          /* link in all/new_channels list */
 152         struct ppp_channel *chan;       /* public channel data structure */
 153         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
 154         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
 155         struct ppp      *ppp;           /* ppp unit we're connected to */
 156         struct list_head clist;         /* link in list of channels per unit */
 157         rwlock_t        upl;            /* protects `ppp' */
 158 #ifdef CONFIG_PPP_MULTILINK
 159         u8              avail;          /* flag used in multilink stuff */
 160         u8              had_frag;       /* >= 1 fragments have been sent */
 161         u32             lastseq;        /* MP: last sequence # received */
 162 #endif /* CONFIG_PPP_MULTILINK */
 163 };
 164
 165 /*
 166  * SMP locking issues:
 167  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
 168  * list and the ppp.n_channels field, you need to take both locks
 169  * before you modify them.
 170  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
 171  * channel.downl.
 172  */
 173
 174 /*
 175  * A cardmap represents a mapping from unsigned integers to pointers,
 176  * and provides a fast "find lowest unused number" operation.
 177  * It uses a broad (32-way) tree with a bitmap at each level.
 178  * It is designed to be space-efficient for small numbers of entries
 179  * and time-efficient for large numbers of entries.
 180  */
 181 #define CARDMAP_ORDER   5
 182 #define CARDMAP_WIDTH   (1U << CARDMAP_ORDER)
 183 #define CARDMAP_MASK    (CARDMAP_WIDTH - 1)
 184
 185 struct cardmap {
 186         int shift;
 187         unsigned long inuse;
 188         struct cardmap *parent;
 189         void *ptr[CARDMAP_WIDTH];
 190 };
 191 static void *cardmap_get(struct cardmap *map, unsigned int nr);
 192 static int cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
 193 static unsigned int cardmap_find_first_free(struct cardmap *map);
 194 static void cardmap_destroy(struct cardmap **map);
 195
 196 /*
 197  * all_ppp_mutex protects the all_ppp_units mapping.
 198  * It also ensures that finding a ppp unit in the all_ppp_units map
 199  * and updating its file.refcnt field is atomic.
 200  */
 201 static DEFINE_MUTEX(all_ppp_mutex);
 202 static struct cardmap *all_ppp_units;
 203 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 204
 205 /*
 206  * all_channels_lock protects all_channels and last_channel_index,
 207  * and the atomicity of find a channel and updating its file.refcnt
 208  * field.
 209  */
 210 static DEFINE_SPINLOCK(all_channels_lock);
 211 static LIST_HEAD(all_channels);
 212 static LIST_HEAD(new_channels);
 213 static int last_channel_index;
 214 static atomic_t channel_count = ATOMIC_INIT(0);
 215
 216 /* Get the PPP protocol number from a skb */
 217 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
 218
 219 /* We limit the length of ppp->file.rq to this (arbitrary) value */
 220 #define PPP_MAX_RQLEN   32
 221
 222 /*
 223  * Maximum number of multilink fragments queued up.
 224  * This has to be large enough to cope with the maximum latency of
 225  * the slowest channel relative to the others.  Strictly it should
 226  * depend on the number of channels and their characteristics.
 227  */
 228 #define PPP_MP_MAX_QLEN 128
 229
 230 /* Multilink header bits. */
 231 #define B       0x80            /* this fragment begins a packet */
 232 #define E       0x40            /* this fragment ends a packet */
 233
 234 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
 235 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
 236 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
 237
 238 /* Prototypes. */
 239 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 240                                 unsigned int cmd, unsigned long arg);
 241 static void ppp_xmit_process(struct ppp *ppp);
 242 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
 243 static void ppp_push(struct ppp *ppp);
 244 static void ppp_channel_push(struct channel *pch);
 245 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
 246                               struct channel *pch);
 247 static void ppp_receive_error(struct ppp *ppp);
 248 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
 249 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
 250                                             struct sk_buff *skb);
 251 #ifdef CONFIG_PPP_MULTILINK
 252 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
 253                                 struct channel *pch);
 254 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
 255 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
 256 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
 257 #endif /* CONFIG_PPP_MULTILINK */
 258 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
 259 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
 260 static void ppp_ccp_closed(struct ppp *ppp);
 261 static struct compressor *find_compressor(int type);
 262 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
 263 static struct ppp *ppp_create_interface(int unit, int *retp);
 264 static void init_ppp_file(struct ppp_file *pf, int kind);
 265 static void ppp_shutdown_interface(struct ppp *ppp);
 266 static void ppp_destroy_interface(struct ppp *ppp);
 267 static struct ppp *ppp_find_unit(int unit);
 268 static struct channel *ppp_find_channel(int unit);
 269 static int ppp_connect_channel(struct channel *pch, int unit);
 270 static int ppp_disconnect_channel(struct channel *pch);
 271 static void ppp_destroy_channel(struct channel *pch);
 272
 273 static struct class *ppp_class;
 274
 275 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
 276 static inline int proto_to_npindex(int proto)
 277 {
 278         switch (proto) {
 279         case PPP_IP:
 280                 return NP_IP;
 281         case PPP_IPV6:
 282                 return NP_IPV6;
 283         case PPP_IPX:
 284                 return NP_IPX;
 285         case PPP_AT:
 286                 return NP_AT;
 287         case PPP_MPLS_UC:
 288                 return NP_MPLS_UC;
 289         case PPP_MPLS_MC:
 290                 return NP_MPLS_MC;
 291         }
 292         return -EINVAL;
 293 }
 294
 295 /* Translates an NP index into a PPP protocol number */
 296 static const int npindex_to_proto[NUM_NP] = {
 297         PPP_IP,
 298         PPP_IPV6,
 299         PPP_IPX,
 300         PPP_AT,
 301         PPP_MPLS_UC,
 302         PPP_MPLS_MC,
 303 };
 304
 305 /* Translates an ethertype into an NP index */
 306 static inline int ethertype_to_npindex(int ethertype)
 307 {
 308         switch (ethertype) {
 309         case ETH_P_IP:
 310                 return NP_IP;
 311         case ETH_P_IPV6:
 312                 return NP_IPV6;
 313         case ETH_P_IPX:
 314                 return NP_IPX;
 315         case ETH_P_PPPTALK:
 316         case ETH_P_ATALK:
 317                 return NP_AT;
 318         case ETH_P_MPLS_UC:
 319                 return NP_MPLS_UC;
 320         case ETH_P_MPLS_MC:
 321                 return NP_MPLS_MC;
 322         }
 323         return -1;
 324 }
 325
 326 /* Translates an NP index into an ethertype */
 327 static const int npindex_to_ethertype[NUM_NP] = {
 328         ETH_P_IP,
 329         ETH_P_IPV6,
 330         ETH_P_IPX,
 331         ETH_P_PPPTALK,
 332         ETH_P_MPLS_UC,
 333         ETH_P_MPLS_MC,
 334 };
 335
 336 /*
 337  * Locking shorthand.
 338  */
 339 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
 340 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
 341 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
 342 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
 343 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
 344                                      ppp_recv_lock(ppp); } while (0)
 345 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
 346                                      ppp_xmit_unlock(ppp); } while (0)
 347
 348 /*
 349  * /dev/ppp device routines.
 350  * The /dev/ppp device is used by pppd to control the ppp unit.
 351  * It supports the read, write, ioctl and poll functions.
 352  * Open instances of /dev/ppp can be in one of three states:
 353  * unattached, attached to a ppp unit, or attached to a ppp channel.
 354  */
 355 static int ppp_open(struct inode *inode, struct file *file)
 356 {
 357         /*
 358          * This could (should?) be enforced by the permissions on /dev/ppp.
 359          */
 360         if (!capable(CAP_NET_ADMIN))
 361                 return -EPERM;
 362         return 0;
 363 }
 364
 365 static int ppp_release(struct inode *inode, struct file *file)
 366 {
 367         struct ppp_file *pf = file->private_data;
 368         struct ppp *ppp;
 369
 370         if (pf != 0) {
 371                 file->private_data = NULL;
 372                 if (pf->kind == INTERFACE) {
 373                         ppp = PF_TO_PPP(pf);
 374                         if (file == ppp->owner)
 375                                 ppp_shutdown_interface(ppp);
 376                 }
 377                 if (atomic_dec_and_test(&pf->refcnt)) {
 378                         switch (pf->kind) {
 379                         case INTERFACE:
 380                                 ppp_destroy_interface(PF_TO_PPP(pf));
 381                                 break;
 382                         case CHANNEL:
 383                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
 384                                 break;
 385                         }
 386                 }
 387         }
 388         return 0;
 389 }
 390
 391 static ssize_t ppp_read(struct file *file, char __user *buf,
 392                         size_t count, loff_t *ppos)
 393 {
 394         struct ppp_file *pf = file->private_data;
 395         DECLARE_WAITQUEUE(wait, current);
 396         ssize_t ret;
 397         struct sk_buff *skb = NULL;
 398
 399         ret = count;
 400
 401         if (pf == 0)
 402                 return -ENXIO;
 403         add_wait_queue(&pf->rwait, &wait);
 404         for (;;) {
 405                 set_current_state(TASK_INTERRUPTIBLE);
 406                 skb = skb_dequeue(&pf->rq);
 407                 if (skb)
 408                         break;
 409                 ret = 0;
 410                 if (pf->dead)
 411                         break;
 412                 if (pf->kind == INTERFACE) {
 413                         /*
 414                          * Return 0 (EOF) on an interface that has no
 415                          * channels connected, unless it is looping
 416                          * network traffic (demand mode).
 417                          */
 418                         struct ppp *ppp = PF_TO_PPP(pf);
 419                         if (ppp->n_channels == 0
 420                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 421                                 break;
 422                 }
 423                 ret = -EAGAIN;
 424                 if (file->f_flags & O_NONBLOCK)
 425                         break;
 426                 ret = -ERESTARTSYS;
 427                 if (signal_pending(current))
 428                         break;
 429                 schedule();
 430         }
 431         set_current_state(TASK_RUNNING);
 432         remove_wait_queue(&pf->rwait, &wait);
 433
 434         if (skb == 0)
 435                 goto out;
 436
 437         ret = -EOVERFLOW;
 438         if (skb->len > count)
 439                 goto outf;
 440         ret = -EFAULT;
 441         if (copy_to_user(buf, skb->data, skb->len))
 442                 goto outf;
 443         ret = skb->len;
 444
 445  outf:
 446         kfree_skb(skb);
 447  out:
 448         return ret;
 449 }
 450
 451 static ssize_t ppp_write(struct file *file, const char __user *buf,
 452                          size_t count, loff_t *ppos)
 453 {
 454         struct ppp_file *pf = file->private_data;
 455         struct sk_buff *skb;
 456         ssize_t ret;
 457
 458         if (pf == 0)
 459                 return -ENXIO;
 460         ret = -ENOMEM;
 461         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
 462         if (skb == 0)
 463                 goto out;
 464         skb_reserve(skb, pf->hdrlen);
 465         ret = -EFAULT;
 466         if (copy_from_user(skb_put(skb, count), buf, count)) {
 467                 kfree_skb(skb);
 468                 goto out;
 469         }
 470
 471         skb_queue_tail(&pf->xq, skb);
 472
 473         switch (pf->kind) {
 474         case INTERFACE:
 475                 ppp_xmit_process(PF_TO_PPP(pf));
 476                 break;
 477         case CHANNEL:
 478                 ppp_channel_push(PF_TO_CHANNEL(pf));
 479                 break;
 480         }
 481
 482         ret = count;
 483
 484  out:
 485         return ret;
 486 }
 487
 488 /* No kernel lock - fine */
 489 static unsigned int ppp_poll(struct file *file, poll_table *wait)
 490 {
 491         struct ppp_file *pf = file->private_data;
 492         unsigned int mask;
 493
 494         if (pf == 0)
 495                 return 0;
 496         poll_wait(file, &pf->rwait, wait);
 497         mask = POLLOUT | POLLWRNORM;
 498         if (skb_peek(&pf->rq) != 0)
 499                 mask |= POLLIN | POLLRDNORM;
 500         if (pf->dead)
 501                 mask |= POLLHUP;
 502         else if (pf->kind == INTERFACE) {
 503                 /* see comment in ppp_read */
 504                 struct ppp *ppp = PF_TO_PPP(pf);
 505                 if (ppp->n_channels == 0
 506                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 507                         mask |= POLLIN | POLLRDNORM;
 508         }
 509
 510         return mask;
 511 }
 512
 513 #ifdef CONFIG_PPP_FILTER
 514 static int get_filter(void __user *arg, struct sock_filter **p)
 515 {
 516         struct sock_fprog uprog;
 517         struct sock_filter *code = NULL;
 518         int len, err;
 519
 520         if (copy_from_user(&uprog, arg, sizeof(uprog)))
 521                 return -EFAULT;
 522
 523         if (!uprog.len) {
 524                 *p = NULL;
 525                 return 0;
 526         }
 527
 528         len = uprog.len * sizeof(struct sock_filter);
 529         code = kmalloc(len, GFP_KERNEL);
 530         if (code == NULL)
 531                 return -ENOMEM;
 532
 533         if (copy_from_user(code, uprog.filter, len)) {
 534                 kfree(code);
 535                 return -EFAULT;
 536         }
 537
 538         err = sk_chk_filter(code, uprog.len);
 539         if (err) {
 540                 kfree(code);
 541                 return err;
 542         }
 543
 544         *p = code;
 545         return uprog.len;
 546 }
 547 #endif /* CONFIG_PPP_FILTER */
 548
 549 static int ppp_ioctl(struct inode *inode, struct file *file,
 550                      unsigned int cmd, unsigned long arg)
 551 {
 552         struct ppp_file *pf = file->private_data;
 553         struct ppp *ppp;
 554         int err = -EFAULT, val, val2, i;
 555         struct ppp_idle idle;
 556         struct npioctl npi;
 557         int unit, cflags;
 558         struct slcompress *vj;
 559         void __user *argp = (void __user *)arg;
 560         int __user *p = argp;
 561
 562         if (pf == 0)
 563                 return ppp_unattached_ioctl(pf, file, cmd, arg);
 564
 565         if (cmd == PPPIOCDETACH) {
 566                 /*
 567                  * We have to be careful here... if the file descriptor
 568                  * has been dup'd, we could have another process in the
 569                  * middle of a poll using the same file *, so we had
 570                  * better not free the interface data structures -
 571                  * instead we fail the ioctl.  Even in this case, we
 572                  * shut down the interface if we are the owner of it.
 573                  * Actually, we should get rid of PPPIOCDETACH, userland
 574                  * (i.e. pppd) could achieve the same effect by closing
 575                  * this fd and reopening /dev/ppp.
 576                  */
 577                 err = -EINVAL;
 578                 if (pf->kind == INTERFACE) {
 579                         ppp = PF_TO_PPP(pf);
 580                         if (file == ppp->owner)
 581                                 ppp_shutdown_interface(ppp);
 582                 }
 583                 if (atomic_read(&file->f_count) <= 2) {
 584                         ppp_release(inode, file);
 585                         err = 0;
 586                 } else
 587                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%d\n",
 588                                atomic_read(&file->f_count));
 589                 return err;
 590         }
 591
 592         if (pf->kind == CHANNEL) {
 593                 struct channel *pch = PF_TO_CHANNEL(pf);
 594                 struct ppp_channel *chan;
 595
 596                 switch (cmd) {
 597                 case PPPIOCCONNECT:
 598                         if (get_user(unit, p))
 599                                 break;
 600                         err = ppp_connect_channel(pch, unit);
 601                         break;
 602
 603                 case PPPIOCDISCONN:
 604                         err = ppp_disconnect_channel(pch);
 605                         break;
 606
 607                 default:
 608                         down_read(&pch->chan_sem);
 609                         chan = pch->chan;
 610                         err = -ENOTTY;
 611                         if (chan && chan->ops->ioctl)
 612                                 err = chan->ops->ioctl(chan, cmd, arg);
 613                         up_read(&pch->chan_sem);
 614                 }
 615                 return err;
 616         }
 617
 618         if (pf->kind != INTERFACE) {
 619                 /* can't happen */
 620                 printk(KERN_ERR "PPP: not interface or channel??\n");
 621                 return -EINVAL;
 622         }
 623
 624         ppp = PF_TO_PPP(pf);
 625         switch (cmd) {
 626         case PPPIOCSMRU:
 627                 if (get_user(val, p))
 628                         break;
 629                 ppp->mru = val;
 630                 err = 0;
 631                 break;
 632
 633         case PPPIOCSFLAGS:
 634                 if (get_user(val, p))
 635                         break;
 636                 ppp_lock(ppp);
 637                 cflags = ppp->flags & ~val;
 638                 ppp->flags = val & SC_FLAG_BITS;
 639                 ppp_unlock(ppp);
 640                 if (cflags & SC_CCP_OPEN)
 641                         ppp_ccp_closed(ppp);
 642                 err = 0;
 643                 break;
 644
 645         case PPPIOCGFLAGS:
 646                 val = ppp->flags | ppp->xstate | ppp->rstate;
 647                 if (put_user(val, p))
 648                         break;
 649                 err = 0;
 650                 break;
 651
 652         case PPPIOCSCOMPRESS:
 653                 err = ppp_set_compress(ppp, arg);
 654                 break;
 655
 656         case PPPIOCGUNIT:
 657                 if (put_user(ppp->file.index, p))
 658                         break;
 659                 err = 0;
 660                 break;
 661
 662         case PPPIOCSDEBUG:
 663                 if (get_user(val, p))
 664                         break;
 665                 ppp->debug = val;
 666                 err = 0;
 667                 break;
 668
 669         case PPPIOCGDEBUG:
 670                 if (put_user(ppp->debug, p))
 671                         break;
 672                 err = 0;
 673                 break;
 674
 675         case PPPIOCGIDLE:
 676                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 677                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
 678                 if (copy_to_user(argp, &idle, sizeof(idle)))
 679                         break;
 680                 err = 0;
 681                 break;
 682
 683         case PPPIOCSMAXCID:
 684                 if (get_user(val, p))
 685                         break;
 686                 val2 = 15;
 687                 if ((val >> 16) != 0) {
 688                         val2 = val >> 16;
 689                         val &= 0xffff;
 690                 }
 691                 vj = slhc_init(val2+1, val+1);
 692                 if (vj == 0) {
 693                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
 694                         err = -ENOMEM;
 695                         break;
 696                 }
 697                 ppp_lock(ppp);
 698                 if (ppp->vj != 0)
 699                         slhc_free(ppp->vj);
 700                 ppp->vj = vj;
 701                 ppp_unlock(ppp);
 702                 err = 0;
 703                 break;
 704
 705         case PPPIOCGNPMODE:
 706         case PPPIOCSNPMODE:
 707                 if (copy_from_user(&npi, argp, sizeof(npi)))
 708                         break;
 709                 err = proto_to_npindex(npi.protocol);
 710                 if (err < 0)
 711                         break;
 712                 i = err;
 713                 if (cmd == PPPIOCGNPMODE) {
 714                         err = -EFAULT;
 715                         npi.mode = ppp->npmode[i];
 716                         if (copy_to_user(argp, &npi, sizeof(npi)))
 717                                 break;
 718                 } else {
 719                         ppp->npmode[i] = npi.mode;
 720                         /* we may be able to transmit more packets now (??) */
 721                         netif_wake_queue(ppp->dev);
 722                 }
 723                 err = 0;
 724                 break;
 725
 726 #ifdef CONFIG_PPP_FILTER
 727         case PPPIOCSPASS:
 728         {
 729                 struct sock_filter *code;
 730                 err = get_filter(argp, &code);
 731                 if (err >= 0) {
 732                         ppp_lock(ppp);
 733                         kfree(ppp->pass_filter);
 734                         ppp->pass_filter = code;
 735                         ppp->pass_len = err;
 736                         ppp_unlock(ppp);
 737                         err = 0;
 738                 }
 739                 break;
 740         }
 741         case PPPIOCSACTIVE:
 742         {
 743                 struct sock_filter *code;
 744                 err = get_filter(argp, &code);
 745                 if (err >= 0) {
 746                         ppp_lock(ppp);
 747                         kfree(ppp->active_filter);
 748                         ppp->active_filter = code;
 749                         ppp->active_len = err;
 750                         ppp_unlock(ppp);
 751                         err = 0;
 752                 }
 753                 break;
 754         }
 755 #endif /* CONFIG_PPP_FILTER */
 756
 757 #ifdef CONFIG_PPP_MULTILINK
 758         case PPPIOCSMRRU:
 759                 if (get_user(val, p))
 760                         break;
 761                 ppp_recv_lock(ppp);
 762                 ppp->mrru = val;
 763                 ppp_recv_unlock(ppp);
 764                 err = 0;
 765                 break;
 766 #endif /* CONFIG_PPP_MULTILINK */
 767
 768         default:
 769                 err = -ENOTTY;
 770         }
 771
 772         return err;
 773 }
 774
 775 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 776                                 unsigned int cmd, unsigned long arg)
 777 {
 778         int unit, err = -EFAULT;
 779         struct ppp *ppp;
 780         struct channel *chan;
 781         int __user *p = (int __user *)arg;
 782
 783         switch (cmd) {
 784         case PPPIOCNEWUNIT:
 785                 /* Create a new ppp unit */
 786                 if (get_user(unit, p))
 787                         break;
 788                 ppp = ppp_create_interface(unit, &err);
 789                 if (ppp == 0)
 790                         break;
 791                 file->private_data = &ppp->file;
 792                 ppp->owner = file;
 793                 err = -EFAULT;
 794                 if (put_user(ppp->file.index, p))
 795                         break;
 796                 err = 0;
 797                 break;
 798
 799         case PPPIOCATTACH:
 800                 /* Attach to an existing ppp unit */
 801                 if (get_user(unit, p))
 802                         break;
 803                 mutex_lock(&all_ppp_mutex);
 804                 err = -ENXIO;
 805                 ppp = ppp_find_unit(unit);
 806                 if (ppp != 0) {
 807                         atomic_inc(&ppp->file.refcnt);
 808                         file->private_data = &ppp->file;
 809                         err = 0;
 810                 }
 811                 mutex_unlock(&all_ppp_mutex);
 812                 break;
 813
 814         case PPPIOCATTCHAN:
 815                 if (get_user(unit, p))
 816                         break;
 817                 spin_lock_bh(&all_channels_lock);
 818                 err = -ENXIO;
 819                 chan = ppp_find_channel(unit);
 820                 if (chan != 0) {
 821                         atomic_inc(&chan->file.refcnt);
 822                         file->private_data = &chan->file;
 823                         err = 0;
 824                 }
 825                 spin_unlock_bh(&all_channels_lock);
 826                 break;
 827
 828         default:
 829                 err = -ENOTTY;
 830         }
 831         return err;
 832 }
 833
 834 static const struct file_operations ppp_device_fops = {
 835         .owner          = THIS_MODULE,
 836         .read           = ppp_read,
 837         .write          = ppp_write,
 838         .poll           = ppp_poll,
 839         .ioctl          = ppp_ioctl,
 840         .open           = ppp_open,
 841         .release        = ppp_release
 842 };
 843
 844 #define PPP_MAJOR       108
 845
 846 /* Called at boot time if ppp is compiled into the kernel,
 847    or at module load time (from init_module) if compiled as a module. */
 848 static int __init ppp_init(void)
 849 {
 850         int err;
 851
 852         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
 853         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
 854         if (!err) {
 855                 ppp_class = class_create(THIS_MODULE, "ppp");
 856                 if (IS_ERR(ppp_class)) {
 857                         err = PTR_ERR(ppp_class);
 858                         goto out_chrdev;
 859                 }
 860                 device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), "ppp");
 861         }
 862
 863 out:
 864         if (err)
 865                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
 866         return err;
 867
 868 out_chrdev:
 869         unregister_chrdev(PPP_MAJOR, "ppp");
 870         goto out;
 871 }
 872
 873 /*
 874  * Network interface unit routines.
 875  */
 876 static int
 877 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 878 {
 879         struct ppp *ppp = (struct ppp *) dev->priv;
 880         int npi, proto;
 881         unsigned char *pp;
 882
 883         npi = ethertype_to_npindex(ntohs(skb->protocol));
 884         if (npi < 0)
 885                 goto outf;
 886
 887         /* Drop, accept or reject the packet */
 888         switch (ppp->npmode[npi]) {
 889         case NPMODE_PASS:
 890                 break;
 891         case NPMODE_QUEUE:
 892                 /* it would be nice to have a way to tell the network
 893                    system to queue this one up for later. */
 894                 goto outf;
 895         case NPMODE_DROP:
 896         case NPMODE_ERROR:
 897                 goto outf;
 898         }
 899
 900         /* Put the 2-byte PPP protocol number on the front,
 901            making sure there is room for the address and control fields. */
 902         if (skb_cow_head(skb, PPP_HDRLEN))
 903                 goto outf;
 904
 905         pp = skb_push(skb, 2);
 906         proto = npindex_to_proto[npi];
 907         pp[0] = proto >> 8;
 908         pp[1] = proto;
 909
 910         netif_stop_queue(dev);
 911         skb_queue_tail(&ppp->file.xq, skb);
 912         ppp_xmit_process(ppp);
 913         return 0;
 914
 915  outf:
 916         kfree_skb(skb);
 917         ++ppp->stats.tx_dropped;
 918         return 0;
 919 }
 920
 921 static struct net_device_stats *
 922 ppp_net_stats(struct net_device *dev)
 923 {
 924         struct ppp *ppp = (struct ppp *) dev->priv;
 925
 926         return &ppp->stats;
 927 }
 928
 929 static int
 930 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 931 {
 932         struct ppp *ppp = dev->priv;
 933         int err = -EFAULT;
 934         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
 935         struct ppp_stats stats;
 936         struct ppp_comp_stats cstats;
 937         char *vers;
 938
 939         switch (cmd) {
 940         case SIOCGPPPSTATS:
 941                 ppp_get_stats(ppp, &stats);
 942                 if (copy_to_user(addr, &stats, sizeof(stats)))
 943                         break;
 944                 err = 0;
 945                 break;
 946
 947         case SIOCGPPPCSTATS:
 948                 memset(&cstats, 0, sizeof(cstats));
 949                 if (ppp->xc_state != 0)
 950                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
 951                 if (ppp->rc_state != 0)
 952                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
 953                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
 954                         break;
 955                 err = 0;
 956                 break;
 957
 958         case SIOCGPPPVER:
 959                 vers = PPP_VERSION;
 960                 if (copy_to_user(addr, vers, strlen(vers) + 1))
 961                         break;
 962                 err = 0;
 963                 break;
 964
 965         default:
 966                 err = -EINVAL;
 967         }
 968
 969         return err;
 970 }
 971
 972 static void ppp_setup(struct net_device *dev)
 973 {
 974         dev->hard_header_len = PPP_HDRLEN;
 975         dev->mtu = PPP_MTU;
 976         dev->addr_len = 0;
 977         dev->tx_queue_len = 3;
 978         dev->type = ARPHRD_PPP;
 979         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
 980 }
 981
 982 /*
 983  * Transmit-side routines.
 984  */
 985
 986 /*
 987  * Called to do any work queued up on the transmit side
 988  * that can now be done.
 989  */
 990 static void
 991 ppp_xmit_process(struct ppp *ppp)
 992 {
 993         struct sk_buff *skb;
 994
 995         ppp_xmit_lock(ppp);
 996         if (ppp->dev != 0) {
 997                 ppp_push(ppp);
 998                 while (ppp->xmit_pending == 0
 999                        && (skb = skb_dequeue(&ppp->file.xq)) != 0)
1000                         ppp_send_frame(ppp, skb);
1001                 /* If there's no work left to do, tell the core net
1002                    code that we can accept some more. */
1003                 if (ppp->xmit_pending == 0 && skb_peek(&ppp->file.xq) == 0)
1004                         netif_wake_queue(ppp->dev);
1005         }
1006         ppp_xmit_unlock(ppp);
1007 }
1008
1009 static inline struct sk_buff *
1010 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1011 {
1012         struct sk_buff *new_skb;
1013         int len;
1014         int new_skb_size = ppp->dev->mtu +
1015                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1016         int compressor_skb_size = ppp->dev->mtu +
1017                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1018         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1019         if (!new_skb) {
1020                 if (net_ratelimit())
1021                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1022                 return NULL;
1023         }
1024         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1025                 skb_reserve(new_skb,
1026                             ppp->dev->hard_header_len - PPP_HDRLEN);
1027
1028         /* compressor still expects A/C bytes in hdr */
1029         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1030                                    new_skb->data, skb->len + 2,
1031                                    compressor_skb_size);
1032         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1033                 kfree_skb(skb);
1034                 skb = new_skb;
1035                 skb_put(skb, len);
1036                 skb_pull(skb, 2);       /* pull off A/C bytes */
1037         } else if (len == 0) {
1038                 /* didn't compress, or CCP not up yet */
1039                 kfree_skb(new_skb);
1040                 new_skb = skb;
1041         } else {
1042                 /*
1043                  * (len < 0)
1044                  * MPPE requires that we do not send unencrypted
1045                  * frames.  The compressor will return -1 if we
1046                  * should drop the frame.  We cannot simply test
1047                  * the compress_proto because MPPE and MPPC share
1048                  * the same number.
1049                  */
1050                 if (net_ratelimit())
1051                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1052                 kfree_skb(skb);
1053                 kfree_skb(new_skb);
1054                 new_skb = NULL;
1055         }
1056         return new_skb;
1057 }
1058
1059 /*
1060  * Compress and send a frame.
1061  * The caller should have locked the xmit path,
1062  * and xmit_pending should be 0.
1063  */
1064 static void
1065 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1066 {
1067         int proto = PPP_PROTO(skb);
1068         struct sk_buff *new_skb;
1069         int len;
1070         unsigned char *cp;
1071
1072         if (proto < 0x8000) {
1073 #ifdef CONFIG_PPP_FILTER
1074                 /* check if we should pass this packet */
1075                 /* the filter instructions are constructed assuming
1076                    a four-byte PPP header on each packet */
1077                 *skb_push(skb, 2) = 1;
1078                 if (ppp->pass_filter
1079                     && sk_run_filter(skb, ppp->pass_filter,
1080                                      ppp->pass_len) == 0) {
1081                         if (ppp->debug & 1)
1082                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1083                         kfree_skb(skb);
1084                         return;
1085                 }
1086                 /* if this packet passes the active filter, record the time */
1087                 if (!(ppp->active_filter
1088                       && sk_run_filter(skb, ppp->active_filter,
1089                                        ppp->active_len) == 0))
1090                         ppp->last_xmit = jiffies;
1091                 skb_pull(skb, 2);
1092 #else
1093                 /* for data packets, record the time */
1094                 ppp->last_xmit = jiffies;
1095 #endif /* CONFIG_PPP_FILTER */
1096         }
1097
1098         ++ppp->stats.tx_packets;
1099         ppp->stats.tx_bytes += skb->len - 2;
1100
1101         switch (proto) {
1102         case PPP_IP:
1103                 if (ppp->vj == 0 || (ppp->flags & SC_COMP_TCP) == 0)
1104                         break;
1105                 /* try to do VJ TCP header compression */
1106                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1107                                     GFP_ATOMIC);
1108                 if (new_skb == 0) {
1109                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1110                         goto drop;
1111                 }
1112                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1113                 cp = skb->data + 2;
1114                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1115                                     new_skb->data + 2, &cp,
1116                                     !(ppp->flags & SC_NO_TCP_CCID));
1117                 if (cp == skb->data + 2) {
1118                         /* didn't compress */
1119                         kfree_skb(new_skb);
1120                 } else {
1121                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1122                                 proto = PPP_VJC_COMP;
1123                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1124                         } else {
1125                                 proto = PPP_VJC_UNCOMP;
1126                                 cp[0] = skb->data[2];
1127                         }
1128                         kfree_skb(skb);
1129                         skb = new_skb;
1130                         cp = skb_put(skb, len + 2);
1131                         cp[0] = 0;
1132                         cp[1] = proto;
1133                 }
1134                 break;
1135
1136         case PPP_CCP:
1137                 /* peek at outbound CCP frames */
1138                 ppp_ccp_peek(ppp, skb, 0);
1139                 break;
1140         }
1141
1142         /* try to do packet compression */
1143         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0
1144             && proto != PPP_LCP && proto != PPP_CCP) {
1145                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1146                         if (net_ratelimit())
1147                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1148                         goto drop;
1149                 }
1150                 skb = pad_compress_skb(ppp, skb);
1151                 if (!skb)
1152                         goto drop;
1153         }
1154
1155         /*
1156          * If we are waiting for traffic (demand dialling),
1157          * queue it up for pppd to receive.
1158          */
1159         if (ppp->flags & SC_LOOP_TRAFFIC) {
1160                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1161                         goto drop;
1162                 skb_queue_tail(&ppp->file.rq, skb);
1163                 wake_up_interruptible(&ppp->file.rwait);
1164                 return;
1165         }
1166
1167         ppp->xmit_pending = skb;
1168         ppp_push(ppp);
1169         return;
1170
1171  drop:
1172         if (skb)
1173                 kfree_skb(skb);
1174         ++ppp->stats.tx_errors;
1175 }
1176
1177 /*
1178  * Try to send the frame in xmit_pending.
1179  * The caller should have the xmit path locked.
1180  */
1181 static void
1182 ppp_push(struct ppp *ppp)
1183 {
1184         struct list_head *list;
1185         struct channel *pch;
1186         struct sk_buff *skb = ppp->xmit_pending;
1187
1188         if (skb == 0)
1189                 return;
1190
1191         list = &ppp->channels;
1192         if (list_empty(list)) {
1193                 /* nowhere to send the packet, just drop it */
1194                 ppp->xmit_pending = NULL;
1195                 kfree_skb(skb);
1196                 return;
1197         }
1198
1199         if ((ppp->flags & SC_MULTILINK) == 0) {
1200                 /* not doing multilink: send it down the first channel */
1201                 list = list->next;
1202                 pch = list_entry(list, struct channel, clist);
1203
1204                 spin_lock_bh(&pch->downl);
1205                 if (pch->chan) {
1206                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1207                                 ppp->xmit_pending = NULL;
1208                 } else {
1209                         /* channel got unregistered */
1210                         kfree_skb(skb);
1211                         ppp->xmit_pending = NULL;
1212                 }
1213                 spin_unlock_bh(&pch->downl);
1214                 return;
1215         }
1216
1217 #ifdef CONFIG_PPP_MULTILINK
1218         /* Multilink: fragment the packet over as many links
1219            as can take the packet at the moment. */
1220         if (!ppp_mp_explode(ppp, skb))
1221                 return;
1222 #endif /* CONFIG_PPP_MULTILINK */
1223
1224         ppp->xmit_pending = NULL;
1225         kfree_skb(skb);
1226 }
1227
1228 #ifdef CONFIG_PPP_MULTILINK
1229 /*
1230  * Divide a packet to be transmitted into fragments and
1231  * send them out the individual links.
1232  */
1233 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1234 {
1235         int len, fragsize;
1236         int i, bits, hdrlen, mtu;
1237         int flen;
1238         int navail, nfree;
1239         int nbigger;
1240         unsigned char *p, *q;
1241         struct list_head *list;
1242         struct channel *pch;
1243         struct sk_buff *frag;
1244         struct ppp_channel *chan;
1245
1246         nfree = 0;      /* # channels which have no packet already queued */
1247         navail = 0;     /* total # of usable channels (not deregistered) */
1248         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1249         i = 0;
1250         list_for_each_entry(pch, &ppp->channels, clist) {
1251                 navail += pch->avail = (pch->chan != NULL);
1252                 if (pch->avail) {
1253                         if (skb_queue_empty(&pch->file.xq) ||
1254                             !pch->had_frag) {
1255                                 pch->avail = 2;
1256                                 ++nfree;
1257                         }
1258                         if (!pch->had_frag && i < ppp->nxchan)
1259                                 ppp->nxchan = i;
1260                 }
1261                 ++i;
1262         }
1263
1264         /*
1265          * Don't start sending this packet unless at least half of
1266          * the channels are free.  This gives much better TCP
1267          * performance if we have a lot of channels.
1268          */
1269         if (nfree == 0 || nfree < navail / 2)
1270                 return 0;       /* can't take now, leave it in xmit_pending */
1271
1272         /* Do protocol field compression (XXX this should be optional) */
1273         p = skb->data;
1274         len = skb->len;
1275         if (*p == 0) {
1276                 ++p;
1277                 --len;
1278         }
1279
1280         /*
1281          * Decide on fragment size.
1282          * We create a fragment for each free channel regardless of
1283          * how small they are (i.e. even 0 length) in order to minimize
1284          * the time that it will take to detect when a channel drops
1285          * a fragment.
1286          */
1287         fragsize = len;
1288         if (nfree > 1)
1289                 fragsize = DIV_ROUND_UP(fragsize, nfree);
1290         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1291            except if nbigger==0, then they all get fragsize. */
1292         nbigger = len % nfree;
1293
1294         /* skip to the channel after the one we last used
1295            and start at that one */
1296         list = &ppp->channels;
1297         for (i = 0; i < ppp->nxchan; ++i) {
1298                 list = list->next;
1299                 if (list == &ppp->channels) {
1300                         i = 0;
1301                         break;
1302                 }
1303         }
1304
1305         /* create a fragment for each channel */
1306         bits = B;
1307         while (nfree > 0 || len > 0) {
1308                 list = list->next;
1309                 if (list == &ppp->channels) {
1310                         i = 0;
1311                         continue;
1312                 }
1313                 pch = list_entry(list, struct channel, clist);
1314                 ++i;
1315                 if (!pch->avail)
1316                         continue;
1317
1318                 /*
1319                  * Skip this channel if it has a fragment pending already and
1320                  * we haven't given a fragment to all of the free channels.
1321                  */
1322                 if (pch->avail == 1) {
1323                         if (nfree > 0)
1324                                 continue;
1325                 } else {
1326                         --nfree;
1327                         pch->avail = 1;
1328                 }
1329
1330                 /* check the channel's mtu and whether it is still attached. */
1331                 spin_lock_bh(&pch->downl);
1332                 if (pch->chan == NULL) {
1333                         /* can't use this channel, it's being deregistered */
1334                         spin_unlock_bh(&pch->downl);
1335                         pch->avail = 0;
1336                         if (--navail == 0)
1337                                 break;
1338                         continue;
1339                 }
1340
1341                 /*
1342                  * Create a fragment for this channel of
1343                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1344                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1345                  * MTU, so we use mtu = 2 + hdrlen.
1346                  */
1347                 if (fragsize > len)
1348                         fragsize = len;
1349                 flen = fragsize;
1350                 mtu = pch->chan->mtu + 2 - hdrlen;
1351                 if (mtu < 4)
1352                         mtu = 4;
1353                 if (flen > mtu)
1354                         flen = mtu;
1355                 if (flen == len && nfree == 0)
1356                         bits |= E;
1357                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1358                 if (frag == 0)
1359                         goto noskb;
1360                 q = skb_put(frag, flen + hdrlen);
1361
1362                 /* make the MP header */
1363                 q[0] = PPP_MP >> 8;
1364                 q[1] = PPP_MP;
1365                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1366                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1367                         q[3] = ppp->nxseq;
1368                 } else {
1369                         q[2] = bits;
1370                         q[3] = ppp->nxseq >> 16;
1371                         q[4] = ppp->nxseq >> 8;
1372                         q[5] = ppp->nxseq;
1373                 }
1374
1375                 /*
1376                  * Copy the data in.
1377                  * Unfortunately there is a bug in older versions of
1378                  * the Linux PPP multilink reconstruction code where it
1379                  * drops 0-length fragments.  Therefore we make sure the
1380                  * fragment has at least one byte of data.  Any bytes
1381                  * we add in this situation will end up as padding on the
1382                  * end of the reconstructed packet.
1383                  */
1384                 if (flen == 0)
1385                         *skb_put(frag, 1) = 0;
1386                 else
1387                         memcpy(q + hdrlen, p, flen);
1388
1389                 /* try to send it down the channel */
1390                 chan = pch->chan;
1391                 if (!skb_queue_empty(&pch->file.xq) ||
1392                     !chan->ops->start_xmit(chan, frag))
1393                         skb_queue_tail(&pch->file.xq, frag);
1394                 pch->had_frag = 1;
1395                 p += flen;
1396                 len -= flen;
1397                 ++ppp->nxseq;
1398                 bits = 0;
1399                 spin_unlock_bh(&pch->downl);
1400
1401                 if (--nbigger == 0 && fragsize > 0)
1402                         --fragsize;
1403         }
1404         ppp->nxchan = i;
1405
1406         return 1;
1407
1408  noskb:
1409         spin_unlock_bh(&pch->downl);
1410         if (ppp->debug & 1)
1411                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1412         ++ppp->stats.tx_errors;
1413         ++ppp->nxseq;
1414         return 1;       /* abandon the frame */
1415 }
1416 #endif /* CONFIG_PPP_MULTILINK */
1417
1418 /*
1419  * Try to send data out on a channel.
1420  */
1421 static void
1422 ppp_channel_push(struct channel *pch)
1423 {
1424         struct sk_buff *skb;
1425         struct ppp *ppp;
1426
1427         spin_lock_bh(&pch->downl);
1428         if (pch->chan != 0) {
1429                 while (!skb_queue_empty(&pch->file.xq)) {
1430                         skb = skb_dequeue(&pch->file.xq);
1431                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1432                                 /* put the packet back and try again later */
1433                                 skb_queue_head(&pch->file.xq, skb);
1434                                 break;
1435                         }
1436                 }
1437         } else {
1438                 /* channel got deregistered */
1439                 skb_queue_purge(&pch->file.xq);
1440         }
1441         spin_unlock_bh(&pch->downl);
1442         /* see if there is anything from the attached unit to be sent */
1443         if (skb_queue_empty(&pch->file.xq)) {
1444                 read_lock_bh(&pch->upl);
1445                 ppp = pch->ppp;
1446                 if (ppp != 0)
1447                         ppp_xmit_process(ppp);
1448                 read_unlock_bh(&pch->upl);
1449         }
1450 }
1451
1452 /*
1453  * Receive-side routines.
1454  */
1455
1456 /* misuse a few fields of the skb for MP reconstruction */
1457 #define sequence        priority
1458 #define BEbits          cb[0]
1459
1460 static inline void
1461 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1462 {
1463         ppp_recv_lock(ppp);
1464         /* ppp->dev == 0 means interface is closing down */
1465         if (ppp->dev != 0)
1466                 ppp_receive_frame(ppp, skb, pch);
1467         else
1468                 kfree_skb(skb);
1469         ppp_recv_unlock(ppp);
1470 }
1471
1472 void
1473 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1474 {
1475         struct channel *pch = chan->ppp;
1476         int proto;
1477
1478         if (pch == 0 || skb->len == 0) {
1479                 kfree_skb(skb);
1480                 return;
1481         }
1482
1483         proto = PPP_PROTO(skb);
1484         read_lock_bh(&pch->upl);
1485         if (pch->ppp == 0 || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1486                 /* put it on the channel queue */
1487                 skb_queue_tail(&pch->file.rq, skb);
1488                 /* drop old frames if queue too long */
1489                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1490                        && (skb = skb_dequeue(&pch->file.rq)) != 0)
1491                         kfree_skb(skb);
1492                 wake_up_interruptible(&pch->file.rwait);
1493         } else {
1494                 ppp_do_recv(pch->ppp, skb, pch);
1495         }
1496         read_unlock_bh(&pch->upl);
1497 }
1498
1499 /* Put a 0-length skb in the receive queue as an error indication */
1500 void
1501 ppp_input_error(struct ppp_channel *chan, int code)
1502 {
1503         struct channel *pch = chan->ppp;
1504         struct sk_buff *skb;
1505
1506         if (pch == 0)
1507                 return;
1508
1509         read_lock_bh(&pch->upl);
1510         if (pch->ppp != 0) {
1511                 skb = alloc_skb(0, GFP_ATOMIC);
1512                 if (skb != 0) {
1513                         skb->len = 0;           /* probably unnecessary */
1514                         skb->cb[0] = code;
1515                         ppp_do_recv(pch->ppp, skb, pch);
1516                 }
1517         }
1518         read_unlock_bh(&pch->upl);
1519 }
1520
1521 /*
1522  * We come in here to process a received frame.
1523  * The receive side of the ppp unit is locked.
1524  */
1525 static void
1526 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1527 {
1528         if (pskb_may_pull(skb, 2)) {
1529 #ifdef CONFIG_PPP_MULTILINK
1530                 /* XXX do channel-level decompression here */
1531                 if (PPP_PROTO(skb) == PPP_MP)
1532                         ppp_receive_mp_frame(ppp, skb, pch);
1533                 else
1534 #endif /* CONFIG_PPP_MULTILINK */
1535                         ppp_receive_nonmp_frame(ppp, skb);
1536                 return;
1537         }
1538
1539         if (skb->len > 0)
1540                 /* note: a 0-length skb is used as an error indication */
1541                 ++ppp->stats.rx_length_errors;
1542
1543         kfree_skb(skb);
1544         ppp_receive_error(ppp);
1545 }
1546
1547 static void
1548 ppp_receive_error(struct ppp *ppp)
1549 {
1550         ++ppp->stats.rx_errors;
1551         if (ppp->vj != 0)
1552                 slhc_toss(ppp->vj);
1553 }
1554
1555 static void
1556 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1557 {
1558         struct sk_buff *ns;
1559         int proto, len, npi;
1560
1561         /*
1562          * Decompress the frame, if compressed.
1563          * Note that some decompressors need to see uncompressed frames
1564          * that come in as well as compressed frames.
1565          */
1566         if (ppp->rc_state != 0 && (ppp->rstate & SC_DECOMP_RUN)
1567             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1568                 skb = ppp_decompress_frame(ppp, skb);
1569
1570         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1571                 goto err;
1572
1573         proto = PPP_PROTO(skb);
1574         switch (proto) {
1575         case PPP_VJC_COMP:
1576                 /* decompress VJ compressed packets */
1577                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1578                         goto err;
1579
1580                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1581                         /* copy to a new sk_buff with more tailroom */
1582                         ns = dev_alloc_skb(skb->len + 128);
1583                         if (ns == 0) {
1584                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1585                                 goto err;
1586                         }
1587                         skb_reserve(ns, 2);
1588                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1589                         kfree_skb(skb);
1590                         skb = ns;
1591                 }
1592                 else
1593                         skb->ip_summed = CHECKSUM_NONE;
1594
1595                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1596                 if (len <= 0) {
1597                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1598                         goto err;
1599                 }
1600                 len += 2;
1601                 if (len > skb->len)
1602                         skb_put(skb, len - skb->len);
1603                 else if (len < skb->len)
1604                         skb_trim(skb, len);
1605                 proto = PPP_IP;
1606                 break;
1607
1608         case PPP_VJC_UNCOMP:
1609                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1610                         goto err;
1611
1612                 /* Until we fix the decompressor need to make sure
1613                  * data portion is linear.
1614                  */
1615                 if (!pskb_may_pull(skb, skb->len))
1616                         goto err;
1617
1618                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1619                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1620                         goto err;
1621                 }
1622                 proto = PPP_IP;
1623                 break;
1624
1625         case PPP_CCP:
1626                 ppp_ccp_peek(ppp, skb, 1);
1627                 break;
1628         }
1629
1630         ++ppp->stats.rx_packets;
1631         ppp->stats.rx_bytes += skb->len - 2;
1632
1633         npi = proto_to_npindex(proto);
1634         if (npi < 0) {
1635                 /* control or unknown frame - pass it to pppd */
1636                 skb_queue_tail(&ppp->file.rq, skb);
1637                 /* limit queue length by dropping old frames */
1638                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1639                        && (skb = skb_dequeue(&ppp->file.rq)) != 0)
1640                         kfree_skb(skb);
1641                 /* wake up any process polling or blocking on read */
1642                 wake_up_interruptible(&ppp->file.rwait);
1643
1644         } else {
1645                 /* network protocol frame - give it to the kernel */
1646
1647 #ifdef CONFIG_PPP_FILTER
1648                 /* check if the packet passes the pass and active filters */
1649                 /* the filter instructions are constructed assuming
1650                    a four-byte PPP header on each packet */
1651                 if (ppp->pass_filter || ppp->active_filter) {
1652                         if (skb_cloned(skb) &&
1653                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
1654                                 goto err;
1655
1656                         *skb_push(skb, 2) = 0;
1657                         if (ppp->pass_filter
1658                             && sk_run_filter(skb, ppp->pass_filter,
1659                                              ppp->pass_len) == 0) {
1660                                 if (ppp->debug & 1)
1661                                         printk(KERN_DEBUG "PPP: inbound frame "
1662                                                "not passed\n");
1663                                 kfree_skb(skb);
1664                                 return;
1665                         }
1666                         if (!(ppp->active_filter
1667                               && sk_run_filter(skb, ppp->active_filter,
1668                                                ppp->active_len) == 0))
1669                                 ppp->last_recv = jiffies;
1670                         __skb_pull(skb, 2);
1671                 } else
1672 #endif /* CONFIG_PPP_FILTER */
1673                         ppp->last_recv = jiffies;
1674
1675                 if ((ppp->dev->flags & IFF_UP) == 0
1676                     || ppp->npmode[npi] != NPMODE_PASS) {
1677                         kfree_skb(skb);
1678                 } else {
1679                         /* chop off protocol */
1680                         skb_pull_rcsum(skb, 2);
1681                         skb->dev = ppp->dev;
1682                         skb->protocol = htons(npindex_to_ethertype[npi]);
1683                         skb_reset_mac_header(skb);
1684                         netif_rx(skb);
1685                         ppp->dev->last_rx = jiffies;
1686                 }
1687         }
1688         return;
1689
1690  err:
1691         kfree_skb(skb);
1692         ppp_receive_error(ppp);
1693 }
1694
1695 static struct sk_buff *
1696 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1697 {
1698         int proto = PPP_PROTO(skb);
1699         struct sk_buff *ns;
1700         int len;
1701
1702         /* Until we fix all the decompressor's need to make sure
1703          * data portion is linear.
1704          */
1705         if (!pskb_may_pull(skb, skb->len))
1706                 goto err;
1707
1708         if (proto == PPP_COMP) {
1709                 int obuff_size;
1710
1711                 switch(ppp->rcomp->compress_proto) {
1712                 case CI_MPPE:
1713                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1714                         break;
1715                 default:
1716                         obuff_size = ppp->mru + PPP_HDRLEN;
1717                         break;
1718                 }
1719
1720                 ns = dev_alloc_skb(obuff_size);
1721                 if (ns == 0) {
1722                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1723                         goto err;
1724                 }
1725                 /* the decompressor still expects the A/C bytes in the hdr */
1726                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1727                                 skb->len + 2, ns->data, obuff_size);
1728                 if (len < 0) {
1729                         /* Pass the compressed frame to pppd as an
1730                            error indication. */
1731                         if (len == DECOMP_FATALERROR)
1732                                 ppp->rstate |= SC_DC_FERROR;
1733                         kfree_skb(ns);
1734                         goto err;
1735                 }
1736
1737                 kfree_skb(skb);
1738                 skb = ns;
1739                 skb_put(skb, len);
1740                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1741
1742         } else {
1743                 /* Uncompressed frame - pass to decompressor so it
1744                    can update its dictionary if necessary. */
1745                 if (ppp->rcomp->incomp)
1746                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1747                                            skb->len + 2);
1748         }
1749
1750         return skb;
1751
1752  err:
1753         ppp->rstate |= SC_DC_ERROR;
1754         ppp_receive_error(ppp);
1755         return skb;
1756 }
1757
1758 #ifdef CONFIG_PPP_MULTILINK
1759 /*
1760  * Receive a multilink frame.
1761  * We put it on the reconstruction queue and then pull off
1762  * as many completed frames as we can.
1763  */
1764 static void
1765 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1766 {
1767         u32 mask, seq;
1768         struct channel *ch;
1769         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1770
1771         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1772                 goto err;               /* no good, throw it away */
1773
1774         /* Decode sequence number and begin/end bits */
1775         if (ppp->flags & SC_MP_SHORTSEQ) {
1776                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1777                 mask = 0xfff;
1778         } else {
1779                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1780                 mask = 0xffffff;
1781         }
1782         skb->BEbits = skb->data[2];
1783         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1784
1785         /*
1786          * Do protocol ID decompression on the first fragment of each packet.
1787          */
1788         if ((skb->BEbits & B) && (skb->data[0] & 1))
1789                 *skb_push(skb, 1) = 0;
1790
1791         /*
1792          * Expand sequence number to 32 bits, making it as close
1793          * as possible to ppp->minseq.
1794          */
1795         seq |= ppp->minseq & ~mask;
1796         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1797                 seq += mask + 1;
1798         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1799                 seq -= mask + 1;        /* should never happen */
1800         skb->sequence = seq;
1801         pch->lastseq = seq;
1802
1803         /*
1804          * If this packet comes before the next one we were expecting,
1805          * drop it.
1806          */
1807         if (seq_before(seq, ppp->nextseq)) {
1808                 kfree_skb(skb);
1809                 ++ppp->stats.rx_dropped;
1810                 ppp_receive_error(ppp);
1811                 return;
1812         }
1813
1814         /*
1815          * Reevaluate minseq, the minimum over all channels of the
1816          * last sequence number received on each channel.  Because of
1817          * the increasing sequence number rule, we know that any fragment
1818          * before `minseq' which hasn't arrived is never going to arrive.
1819          * The list of channels can't change because we have the receive
1820          * side of the ppp unit locked.
1821          */
1822         list_for_each_entry(ch, &ppp->channels, clist) {
1823                 if (seq_before(ch->lastseq, seq))
1824                         seq = ch->lastseq;
1825         }
1826         if (seq_before(ppp->minseq, seq))
1827                 ppp->minseq = seq;
1828
1829         /* Put the fragment on the reconstruction queue */
1830         ppp_mp_insert(ppp, skb);
1831
1832         /* If the queue is getting long, don't wait any longer for packets
1833            before the start of the queue. */
1834         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN
1835             && seq_before(ppp->minseq, ppp->mrq.next->sequence))
1836                 ppp->minseq = ppp->mrq.next->sequence;
1837
1838         /* Pull completed packets off the queue and receive them. */
1839         while ((skb = ppp_mp_reconstruct(ppp)) != 0)
1840                 ppp_receive_nonmp_frame(ppp, skb);
1841
1842         return;
1843
1844  err:
1845         kfree_skb(skb);
1846         ppp_receive_error(ppp);
1847 }
1848
1849 /*
1850  * Insert a fragment on the MP reconstruction queue.
1851  * The queue is ordered by increasing sequence number.
1852  */
1853 static void
1854 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1855 {
1856         struct sk_buff *p;
1857         struct sk_buff_head *list = &ppp->mrq;
1858         u32 seq = skb->sequence;
1859
1860         /* N.B. we don't need to lock the list lock because we have the
1861            ppp unit receive-side lock. */
1862         for (p = list->next; p != (struct sk_buff *)list; p = p->next)
1863                 if (seq_before(seq, p->sequence))
1864                         break;
1865         __skb_insert(skb, p->prev, p, list);
1866 }
1867
1868 /*
1869  * Reconstruct a packet from the MP fragment queue.
1870  * We go through increasing sequence numbers until we find a
1871  * complete packet, or we get to the sequence number for a fragment
1872  * which hasn't arrived but might still do so.
1873  */
1874 struct sk_buff *
1875 ppp_mp_reconstruct(struct ppp *ppp)
1876 {
1877         u32 seq = ppp->nextseq;
1878         u32 minseq = ppp->minseq;
1879         struct sk_buff_head *list = &ppp->mrq;
1880         struct sk_buff *p, *next;
1881         struct sk_buff *head, *tail;
1882         struct sk_buff *skb = NULL;
1883         int lost = 0, len = 0;
1884
1885         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1886                 return NULL;
1887         head = list->next;
1888         tail = NULL;
1889         for (p = head; p != (struct sk_buff *) list; p = next) {
1890                 next = p->next;
1891                 if (seq_before(p->sequence, seq)) {
1892                         /* this can't happen, anyway ignore the skb */
1893                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1894                                p->sequence, seq);
1895                         head = next;
1896                         continue;
1897                 }
1898                 if (p->sequence != seq) {
1899                         /* Fragment `seq' is missing.  If it is after
1900                            minseq, it might arrive later, so stop here. */
1901                         if (seq_after(seq, minseq))
1902                                 break;
1903                         /* Fragment `seq' is lost, keep going. */
1904                         lost = 1;
1905                         seq = seq_before(minseq, p->sequence)?
1906                                 minseq + 1: p->sequence;
1907                         next = p;
1908                         continue;
1909                 }
1910
1911                 /*
1912                  * At this point we know that all the fragments from
1913                  * ppp->nextseq to seq are either present or lost.
1914                  * Also, there are no complete packets in the queue
1915                  * that have no missing fragments and end before this
1916                  * fragment.
1917                  */
1918
1919                 /* B bit set indicates this fragment starts a packet */
1920                 if (p->BEbits & B) {
1921                         head = p;
1922                         lost = 0;
1923                         len = 0;
1924                 }
1925
1926                 len += p->len;
1927
1928                 /* Got a complete packet yet? */
1929                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1930                         if (len > ppp->mrru + 2) {
1931                                 ++ppp->stats.rx_length_errors;
1932                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1933                                        " is too long (%d)\n", len);
1934                         } else if (p == head) {
1935                                 /* fragment is complete packet - reuse skb */
1936                                 tail = p;
1937                                 skb = skb_get(p);
1938                                 break;
1939                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1940                                 ++ppp->stats.rx_missed_errors;
1941                                 printk(KERN_DEBUG "PPP: no memory for "
1942                                        "reconstructed packet");
1943                         } else {
1944                                 tail = p;
1945                                 break;
1946                         }
1947                         ppp->nextseq = seq + 1;
1948                 }
1949
1950                 /*
1951                  * If this is the ending fragment of a packet,
1952                  * and we haven't found a complete valid packet yet,
1953                  * we can discard up to and including this fragment.
1954                  */
1955                 if (p->BEbits & E)
1956                         head = next;
1957
1958                 ++seq;
1959         }
1960
1961         /* If we have a complete packet, copy it all into one skb. */
1962         if (tail != NULL) {
1963                 /* If we have discarded any fragments,
1964                    signal a receive error. */
1965                 if (head->sequence != ppp->nextseq) {
1966                         if (ppp->debug & 1)
1967                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1968                                        ppp->nextseq, head->sequence-1);
1969                         ++ppp->stats.rx_dropped;
1970                         ppp_receive_error(ppp);
1971                 }
1972
1973                 if (head != tail)
1974                         /* copy to a single skb */
1975                         for (p = head; p != tail->next; p = p->next)
1976                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1977                 ppp->nextseq = tail->sequence + 1;
1978                 head = tail->next;
1979         }
1980
1981         /* Discard all the skbuffs that we have copied the data out of
1982            or that we can't use. */
1983         while ((p = list->next) != head) {
1984                 __skb_unlink(p, list);
1985                 kfree_skb(p);
1986         }
1987
1988         return skb;
1989 }
1990 #endif /* CONFIG_PPP_MULTILINK */
1991
1992 /*
1993  * Channel interface.
1994  */
1995
1996 /*
1997  * Create a new, unattached ppp channel.
1998  */
1999 int
2000 ppp_register_channel(struct ppp_channel *chan)
2001 {
2002         struct channel *pch;
2003
2004         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2005         if (pch == 0)
2006                 return -ENOMEM;
2007         pch->ppp = NULL;
2008         pch->chan = chan;
2009         chan->ppp = pch;
2010         init_ppp_file(&pch->file, CHANNEL);
2011         pch->file.hdrlen = chan->hdrlen;
2012 #ifdef CONFIG_PPP_MULTILINK
2013         pch->lastseq = -1;
2014 #endif /* CONFIG_PPP_MULTILINK */
2015         init_rwsem(&pch->chan_sem);
2016         spin_lock_init(&pch->downl);
2017         rwlock_init(&pch->upl);
2018         spin_lock_bh(&all_channels_lock);
2019         pch->file.index = ++last_channel_index;
2020         list_add(&pch->list, &new_channels);
2021         atomic_inc(&channel_count);
2022         spin_unlock_bh(&all_channels_lock);
2023         return 0;
2024 }
2025
2026 /*
2027  * Return the index of a channel.
2028  */
2029 int ppp_channel_index(struct ppp_channel *chan)
2030 {
2031         struct channel *pch = chan->ppp;
2032
2033         if (pch != 0)
2034                 return pch->file.index;
2035         return -1;
2036 }
2037
2038 /*
2039  * Return the PPP unit number to which a channel is connected.
2040  */
2041 int ppp_unit_number(struct ppp_channel *chan)
2042 {
2043         struct channel *pch = chan->ppp;
2044         int unit = -1;
2045
2046         if (pch != 0) {
2047                 read_lock_bh(&pch->upl);
2048                 if (pch->ppp != 0)
2049                         unit = pch->ppp->file.index;
2050                 read_unlock_bh(&pch->upl);
2051         }
2052         return unit;
2053 }
2054
2055 /*
2056  * Disconnect a channel from the generic layer.
2057  * This must be called in process context.
2058  */
2059 void
2060 ppp_unregister_channel(struct ppp_channel *chan)
2061 {
2062         struct channel *pch = chan->ppp;
2063
2064         if (pch == 0)
2065                 return;         /* should never happen */
2066         chan->ppp = NULL;
2067
2068         /*
2069          * This ensures that we have returned from any calls into the
2070          * the channel's start_xmit or ioctl routine before we proceed.
2071          */
2072         down_write(&pch->chan_sem);
2073         spin_lock_bh(&pch->downl);
2074         pch->chan = NULL;
2075         spin_unlock_bh(&pch->downl);
2076         up_write(&pch->chan_sem);
2077         ppp_disconnect_channel(pch);
2078         spin_lock_bh(&all_channels_lock);
2079         list_del(&pch->list);
2080         spin_unlock_bh(&all_channels_lock);
2081         pch->file.dead = 1;
2082         wake_up_interruptible(&pch->file.rwait);
2083         if (atomic_dec_and_test(&pch->file.refcnt))
2084                 ppp_destroy_channel(pch);
2085 }
2086
2087 /*
2088  * Callback from a channel when it can accept more to transmit.
2089  * This should be called at BH/softirq level, not interrupt level.
2090  */
2091 void
2092 ppp_output_wakeup(struct ppp_channel *chan)
2093 {
2094         struct channel *pch = chan->ppp;
2095
2096         if (pch == 0)
2097                 return;
2098         ppp_channel_push(pch);
2099 }
2100
2101 /*
2102  * Compression control.
2103  */
2104
2105 /* Process the PPPIOCSCOMPRESS ioctl. */
2106 static int
2107 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2108 {
2109         int err;
2110         struct compressor *cp, *ocomp;
2111         struct ppp_option_data data;
2112         void *state, *ostate;
2113         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2114
2115         err = -EFAULT;
2116         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2117             || (data.length <= CCP_MAX_OPTION_LENGTH
2118                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2119                 goto out;
2120         err = -EINVAL;
2121         if (data.length > CCP_MAX_OPTION_LENGTH
2122             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2123                 goto out;
2124
2125         cp = find_compressor(ccp_option[0]);
2126 #ifdef CONFIG_KMOD
2127         if (cp == 0) {
2128                 request_module("ppp-compress-%d", ccp_option[0]);
2129                 cp = find_compressor(ccp_option[0]);
2130         }
2131 #endif /* CONFIG_KMOD */
2132         if (cp == 0)
2133                 goto out;
2134
2135         err = -ENOBUFS;
2136         if (data.transmit) {
2137                 state = cp->comp_alloc(ccp_option, data.length);
2138                 if (state != 0) {
2139                         ppp_xmit_lock(ppp);
2140                         ppp->xstate &= ~SC_COMP_RUN;
2141                         ocomp = ppp->xcomp;
2142                         ostate = ppp->xc_state;
2143                         ppp->xcomp = cp;
2144                         ppp->xc_state = state;
2145                         ppp_xmit_unlock(ppp);
2146                         if (ostate != 0) {
2147                                 ocomp->comp_free(ostate);
2148                                 module_put(ocomp->owner);
2149                         }
2150                         err = 0;
2151                 } else
2152                         module_put(cp->owner);
2153
2154         } else {
2155                 state = cp->decomp_alloc(ccp_option, data.length);
2156                 if (state != 0) {
2157                         ppp_recv_lock(ppp);
2158                         ppp->rstate &= ~SC_DECOMP_RUN;
2159                         ocomp = ppp->rcomp;
2160                         ostate = ppp->rc_state;
2161                         ppp->rcomp = cp;
2162                         ppp->rc_state = state;
2163                         ppp_recv_unlock(ppp);
2164                         if (ostate != 0) {
2165                                 ocomp->decomp_free(ostate);
2166                                 module_put(ocomp->owner);
2167                         }
2168                         err = 0;
2169                 } else
2170                         module_put(cp->owner);
2171         }
2172
2173  out:
2174         return err;
2175 }
2176
2177 /*
2178  * Look at a CCP packet and update our state accordingly.
2179  * We assume the caller has the xmit or recv path locked.
2180  */
2181 static void
2182 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2183 {
2184         unsigned char *dp;
2185         int len;
2186
2187         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2188                 return; /* no header */
2189         dp = skb->data + 2;
2190
2191         switch (CCP_CODE(dp)) {
2192         case CCP_CONFREQ:
2193
2194                 /* A ConfReq starts negotiation of compression
2195                  * in one direction of transmission,
2196                  * and hence brings it down...but which way?
2197                  *
2198                  * Remember:
2199                  * A ConfReq indicates what the sender would like to receive
2200                  */
2201                 if(inbound)
2202                         /* He is proposing what I should send */
2203                         ppp->xstate &= ~SC_COMP_RUN;
2204                 else
2205                         /* I am proposing to what he should send */
2206                         ppp->rstate &= ~SC_DECOMP_RUN;
2207
2208                 break;
2209
2210         case CCP_TERMREQ:
2211         case CCP_TERMACK:
2212                 /*
2213                  * CCP is going down, both directions of transmission
2214                  */
2215                 ppp->rstate &= ~SC_DECOMP_RUN;
2216                 ppp->xstate &= ~SC_COMP_RUN;
2217                 break;
2218
2219         case CCP_CONFACK:
2220                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2221                         break;
2222                 len = CCP_LENGTH(dp);
2223                 if (!pskb_may_pull(skb, len + 2))
2224                         return;         /* too short */
2225                 dp += CCP_HDRLEN;
2226                 len -= CCP_HDRLEN;
2227                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2228                         break;
2229                 if (inbound) {
2230                         /* we will start receiving compressed packets */
2231                         if (ppp->rc_state == 0)
2232                                 break;
2233                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2234                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2235                                 ppp->rstate |= SC_DECOMP_RUN;
2236                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2237                         }
2238                 } else {
2239                         /* we will soon start sending compressed packets */
2240                         if (ppp->xc_state == 0)
2241                                 break;
2242                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2243                                         ppp->file.index, 0, ppp->debug))
2244                                 ppp->xstate |= SC_COMP_RUN;
2245                 }
2246                 break;
2247
2248         case CCP_RESETACK:
2249                 /* reset the [de]compressor */
2250                 if ((ppp->flags & SC_CCP_UP) == 0)
2251                         break;
2252                 if (inbound) {
2253                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2254                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2255                                 ppp->rstate &= ~SC_DC_ERROR;
2256                         }
2257                 } else {
2258                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2259                                 ppp->xcomp->comp_reset(ppp->xc_state);
2260                 }
2261                 break;
2262         }
2263 }
2264
2265 /* Free up compression resources. */
2266 static void
2267 ppp_ccp_closed(struct ppp *ppp)
2268 {
2269         void *xstate, *rstate;
2270         struct compressor *xcomp, *rcomp;
2271
2272         ppp_lock(ppp);
2273         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2274         ppp->xstate = 0;
2275         xcomp = ppp->xcomp;
2276         xstate = ppp->xc_state;
2277         ppp->xc_state = NULL;
2278         ppp->rstate = 0;
2279         rcomp = ppp->rcomp;
2280         rstate = ppp->rc_state;
2281         ppp->rc_state = NULL;
2282         ppp_unlock(ppp);
2283
2284         if (xstate) {
2285                 xcomp->comp_free(xstate);
2286                 module_put(xcomp->owner);
2287         }
2288         if (rstate) {
2289                 rcomp->decomp_free(rstate);
2290                 module_put(rcomp->owner);
2291         }
2292 }
2293
2294 /* List of compressors. */
2295 static LIST_HEAD(compressor_list);
2296 static DEFINE_SPINLOCK(compressor_list_lock);
2297
2298 struct compressor_entry {
2299         struct list_head list;
2300         struct compressor *comp;
2301 };
2302
2303 static struct compressor_entry *
2304 find_comp_entry(int proto)
2305 {
2306         struct compressor_entry *ce;
2307
2308         list_for_each_entry(ce, &compressor_list, list) {
2309                 if (ce->comp->compress_proto == proto)
2310                         return ce;
2311         }
2312         return NULL;
2313 }
2314
2315 /* Register a compressor */
2316 int
2317 ppp_register_compressor(struct compressor *cp)
2318 {
2319         struct compressor_entry *ce;
2320         int ret;
2321         spin_lock(&compressor_list_lock);
2322         ret = -EEXIST;
2323         if (find_comp_entry(cp->compress_proto) != 0)
2324                 goto out;
2325         ret = -ENOMEM;
2326         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2327         if (ce == 0)
2328                 goto out;
2329         ret = 0;
2330         ce->comp = cp;
2331         list_add(&ce->list, &compressor_list);
2332  out:
2333         spin_unlock(&compressor_list_lock);
2334         return ret;
2335 }
2336
2337 /* Unregister a compressor */
2338 void
2339 ppp_unregister_compressor(struct compressor *cp)
2340 {
2341         struct compressor_entry *ce;
2342
2343         spin_lock(&compressor_list_lock);
2344         ce = find_comp_entry(cp->compress_proto);
2345         if (ce != 0 && ce->comp == cp) {
2346                 list_del(&ce->list);
2347                 kfree(ce);
2348         }
2349         spin_unlock(&compressor_list_lock);
2350 }
2351
2352 /* Find a compressor. */
2353 static struct compressor *
2354 find_compressor(int type)
2355 {
2356         struct compressor_entry *ce;
2357         struct compressor *cp = NULL;
2358
2359         spin_lock(&compressor_list_lock);
2360         ce = find_comp_entry(type);
2361         if (ce != 0) {
2362                 cp = ce->comp;
2363                 if (!try_module_get(cp->owner))
2364                         cp = NULL;
2365         }
2366         spin_unlock(&compressor_list_lock);
2367         return cp;
2368 }
2369
2370 /*
2371  * Miscelleneous stuff.
2372  */
2373
2374 static void
2375 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2376 {
2377         struct slcompress *vj = ppp->vj;
2378
2379         memset(st, 0, sizeof(*st));
2380         st->p.ppp_ipackets = ppp->stats.rx_packets;
2381         st->p.ppp_ierrors = ppp->stats.rx_errors;
2382         st->p.ppp_ibytes = ppp->stats.rx_bytes;
2383         st->p.ppp_opackets = ppp->stats.tx_packets;
2384         st->p.ppp_oerrors = ppp->stats.tx_errors;
2385         st->p.ppp_obytes = ppp->stats.tx_bytes;
2386         if (vj == 0)
2387                 return;
2388         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2389         st->vj.vjs_compressed = vj->sls_o_compressed;
2390         st->vj.vjs_searches = vj->sls_o_searches;
2391         st->vj.vjs_misses = vj->sls_o_misses;
2392         st->vj.vjs_errorin = vj->sls_i_error;
2393         st->vj.vjs_tossed = vj->sls_i_tossed;
2394         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2395         st->vj.vjs_compressedin = vj->sls_i_compressed;
2396 }
2397
2398 /*
2399  * Stuff for handling the lists of ppp units and channels
2400  * and for initialization.
2401  */
2402
2403 /*
2404  * Create a new ppp interface unit.  Fails if it can't allocate memory
2405  * or if there is already a unit with the requested number.
2406  * unit == -1 means allocate a new number.
2407  */
2408 static struct ppp *
2409 ppp_create_interface(int unit, int *retp)
2410 {
2411         struct ppp *ppp;
2412         struct net_device *dev = NULL;
2413         int ret = -ENOMEM;
2414         int i;
2415
2416         ppp = kzalloc(sizeof(struct ppp), GFP_KERNEL);
2417         if (!ppp)
2418                 goto out;
2419         dev = alloc_netdev(0, "", ppp_setup);
2420         if (!dev)
2421                 goto out1;
2422
2423         ppp->mru = PPP_MRU;
2424         init_ppp_file(&ppp->file, INTERFACE);
2425         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2426         for (i = 0; i < NUM_NP; ++i)
2427                 ppp->npmode[i] = NPMODE_PASS;
2428         INIT_LIST_HEAD(&ppp->channels);
2429         spin_lock_init(&ppp->rlock);
2430         spin_lock_init(&ppp->wlock);
2431 #ifdef CONFIG_PPP_MULTILINK
2432         ppp->minseq = -1;
2433         skb_queue_head_init(&ppp->mrq);
2434 #endif /* CONFIG_PPP_MULTILINK */
2435         ppp->dev = dev;
2436         dev->priv = ppp;
2437
2438         dev->hard_start_xmit = ppp_start_xmit;
2439         dev->get_stats = ppp_net_stats;
2440         dev->do_ioctl = ppp_net_ioctl;
2441
2442         ret = -EEXIST;
2443         mutex_lock(&all_ppp_mutex);
2444         if (unit < 0)
2445                 unit = cardmap_find_first_free(all_ppp_units);
2446         else if (cardmap_get(all_ppp_units, unit) != NULL)
2447                 goto out2;      /* unit already exists */
2448
2449         /* Initialize the new ppp unit */
2450         ppp->file.index = unit;
2451         sprintf(dev->name, "ppp%d", unit);
2452
2453         ret = register_netdev(dev);
2454         if (ret != 0) {
2455                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2456                        dev->name, ret);
2457                 goto out2;
2458         }
2459
2460         atomic_inc(&ppp_unit_count);
2461         ret = cardmap_set(&all_ppp_units, unit, ppp);
2462         if (ret != 0)
2463                 goto out3;
2464
2465         mutex_unlock(&all_ppp_mutex);
2466         *retp = 0;
2467         return ppp;
2468
2469 out3:
2470         atomic_dec(&ppp_unit_count);
2471 out2:
2472         mutex_unlock(&all_ppp_mutex);
2473         free_netdev(dev);
2474 out1:
2475         kfree(ppp);
2476 out:
2477         *retp = ret;
2478         return NULL;
2479 }
2480
2481 /*
2482  * Initialize a ppp_file structure.
2483  */
2484 static void
2485 init_ppp_file(struct ppp_file *pf, int kind)
2486 {
2487         pf->kind = kind;
2488         skb_queue_head_init(&pf->xq);
2489         skb_queue_head_init(&pf->rq);
2490         atomic_set(&pf->refcnt, 1);
2491         init_waitqueue_head(&pf->rwait);
2492 }
2493
2494 /*
2495  * Take down a ppp interface unit - called when the owning file
2496  * (the one that created the unit) is closed or detached.
2497  */
2498 static void ppp_shutdown_interface(struct ppp *ppp)
2499 {
2500         struct net_device *dev;
2501
2502         mutex_lock(&all_ppp_mutex);
2503         ppp_lock(ppp);
2504         dev = ppp->dev;
2505         ppp->dev = NULL;
2506         ppp_unlock(ppp);
2507         /* This will call dev_close() for us. */
2508         if (dev) {
2509                 unregister_netdev(dev);
2510                 free_netdev(dev);
2511         }
2512         cardmap_set(&all_ppp_units, ppp->file.index, NULL);
2513         ppp->file.dead = 1;
2514         ppp->owner = NULL;
2515         wake_up_interruptible(&ppp->file.rwait);
2516         mutex_unlock(&all_ppp_mutex);
2517 }
2518
2519 /*
2520  * Free the memory used by a ppp unit.  This is only called once
2521  * there are no channels connected to the unit and no file structs
2522  * that reference the unit.
2523  */
2524 static void ppp_destroy_interface(struct ppp *ppp)
2525 {
2526         atomic_dec(&ppp_unit_count);
2527
2528         if (!ppp->file.dead || ppp->n_channels) {
2529                 /* "can't happen" */
2530                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2531                        "n_channels=%d !\n", ppp, ppp->file.dead,
2532                        ppp->n_channels);
2533                 return;
2534         }
2535
2536         ppp_ccp_closed(ppp);
2537         if (ppp->vj) {
2538                 slhc_free(ppp->vj);
2539                 ppp->vj = NULL;
2540         }
2541         skb_queue_purge(&ppp->file.xq);
2542         skb_queue_purge(&ppp->file.rq);
2543 #ifdef CONFIG_PPP_MULTILINK
2544         skb_queue_purge(&ppp->mrq);
2545 #endif /* CONFIG_PPP_MULTILINK */
2546 #ifdef CONFIG_PPP_FILTER
2547         kfree(ppp->pass_filter);
2548         ppp->pass_filter = NULL;
2549         kfree(ppp->active_filter);
2550         ppp->active_filter = NULL;
2551 #endif /* CONFIG_PPP_FILTER */
2552
2553         if (ppp->xmit_pending)
2554                 kfree_skb(ppp->xmit_pending);
2555
2556         kfree(ppp);
2557 }
2558
2559 /*
2560  * Locate an existing ppp unit.
2561  * The caller should have locked the all_ppp_mutex.
2562  */
2563 static struct ppp *
2564 ppp_find_unit(int unit)
2565 {
2566         return cardmap_get(all_ppp_units, unit);
2567 }
2568
2569 /*
2570  * Locate an existing ppp channel.
2571  * The caller should have locked the all_channels_lock.
2572  * First we look in the new_channels list, then in the
2573  * all_channels list.  If found in the new_channels list,
2574  * we move it to the all_channels list.  This is for speed
2575  * when we have a lot of channels in use.
2576  */
2577 static struct channel *
2578 ppp_find_channel(int unit)
2579 {
2580         struct channel *pch;
2581
2582         list_for_each_entry(pch, &new_channels, list) {
2583                 if (pch->file.index == unit) {
2584                         list_move(&pch->list, &all_channels);
2585                         return pch;
2586                 }
2587         }
2588         list_for_each_entry(pch, &all_channels, list) {
2589                 if (pch->file.index == unit)
2590                         return pch;
2591         }
2592         return NULL;
2593 }
2594
2595 /*
2596  * Connect a PPP channel to a PPP interface unit.
2597  */
2598 static int
2599 ppp_connect_channel(struct channel *pch, int unit)
2600 {
2601         struct ppp *ppp;
2602         int ret = -ENXIO;
2603         int hdrlen;
2604
2605         mutex_lock(&all_ppp_mutex);
2606         ppp = ppp_find_unit(unit);
2607         if (ppp == 0)
2608                 goto out;
2609         write_lock_bh(&pch->upl);
2610         ret = -EINVAL;
2611         if (pch->ppp != 0)
2612                 goto outl;
2613
2614         ppp_lock(ppp);
2615         if (pch->file.hdrlen > ppp->file.hdrlen)
2616                 ppp->file.hdrlen = pch->file.hdrlen;
2617         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2618         if (ppp->dev && hdrlen > ppp->dev->hard_header_len)
2619                 ppp->dev->hard_header_len = hdrlen;
2620         list_add_tail(&pch->clist, &ppp->channels);
2621         ++ppp->n_channels;
2622         pch->ppp = ppp;
2623         atomic_inc(&ppp->file.refcnt);
2624         ppp_unlock(ppp);
2625         ret = 0;
2626
2627  outl:
2628         write_unlock_bh(&pch->upl);
2629  out:
2630         mutex_unlock(&all_ppp_mutex);
2631         return ret;
2632 }
2633
2634 /*
2635  * Disconnect a channel from its ppp unit.
2636  */
2637 static int
2638 ppp_disconnect_channel(struct channel *pch)
2639 {
2640         struct ppp *ppp;
2641         int err = -EINVAL;
2642
2643         write_lock_bh(&pch->upl);
2644         ppp = pch->ppp;
2645         pch->ppp = NULL;
2646         write_unlock_bh(&pch->upl);
2647         if (ppp != 0) {
2648                 /* remove it from the ppp unit's list */
2649                 ppp_lock(ppp);
2650                 list_del(&pch->clist);
2651                 if (--ppp->n_channels == 0)
2652                         wake_up_interruptible(&ppp->file.rwait);
2653                 ppp_unlock(ppp);
2654                 if (atomic_dec_and_test(&ppp->file.refcnt))
2655                         ppp_destroy_interface(ppp);
2656                 err = 0;
2657         }
2658         return err;
2659 }
2660
2661 /*
2662  * Free up the resources used by a ppp channel.
2663  */
2664 static void ppp_destroy_channel(struct channel *pch)
2665 {
2666         atomic_dec(&channel_count);
2667
2668         if (!pch->file.dead) {
2669                 /* "can't happen" */
2670                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2671                        pch);
2672                 return;
2673         }
2674         skb_queue_purge(&pch->file.xq);
2675         skb_queue_purge(&pch->file.rq);
2676         kfree(pch);
2677 }
2678
2679 static void __exit ppp_cleanup(void)
2680 {
2681         /* should never happen */
2682         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2683                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2684         cardmap_destroy(&all_ppp_units);
2685         unregister_chrdev(PPP_MAJOR, "ppp");
2686         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2687         class_destroy(ppp_class);
2688 }
2689
2690 /*
2691  * Cardmap implementation.
2692  */
2693 static void *cardmap_get(struct cardmap *map, unsigned int nr)
2694 {
2695         struct cardmap *p;
2696         int i;
2697
2698         for (p = map; p != NULL; ) {
2699                 if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
2700                         return NULL;
2701                 if (p->shift == 0)
2702                         return p->ptr[i];
2703                 nr &= ~(CARDMAP_MASK << p->shift);
2704                 p = p->ptr[i];
2705         }
2706         return NULL;
2707 }
2708
2709 static int cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
2710 {
2711         struct cardmap *p;
2712         int i;
2713
2714         p = *pmap;
2715         if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
2716                 do {
2717                         /* need a new top level */
2718                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2719                         if (!np)
2720                                 goto enomem;
2721                         np->ptr[0] = p;
2722                         if (p != NULL) {
2723                                 np->shift = p->shift + CARDMAP_ORDER;
2724                                 p->parent = np;
2725                         } else
2726                                 np->shift = 0;
2727                         p = np;
2728                 } while ((nr >> p->shift) >= CARDMAP_WIDTH);
2729                 *pmap = p;
2730         }
2731         while (p->shift > 0) {
2732                 i = (nr >> p->shift) & CARDMAP_MASK;
2733                 if (p->ptr[i] == NULL) {
2734                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2735                         if (!np)
2736                                 goto enomem;
2737                         np->shift = p->shift - CARDMAP_ORDER;
2738                         np->parent = p;
2739                         p->ptr[i] = np;
2740                 }
2741                 if (ptr == NULL)
2742                         clear_bit(i, &p->inuse);
2743                 p = p->ptr[i];
2744         }
2745         i = nr & CARDMAP_MASK;
2746         p->ptr[i] = ptr;
2747         if (ptr != NULL)
2748                 set_bit(i, &p->inuse);
2749         else
2750                 clear_bit(i, &p->inuse);
2751         return 0;
2752  enomem:
2753         return -ENOMEM;
2754 }
2755
2756 static unsigned int cardmap_find_first_free(struct cardmap *map)
2757 {
2758         struct cardmap *p;
2759         unsigned int nr = 0;
2760         int i;
2761
2762         if ((p = map) == NULL)
2763                 return 0;
2764         for (;;) {
2765                 i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
2766                 if (i >= CARDMAP_WIDTH) {
2767                         if (p->parent == NULL)
2768                                 return CARDMAP_WIDTH << p->shift;
2769                         p = p->parent;
2770                         i = (nr >> p->shift) & CARDMAP_MASK;
2771                         set_bit(i, &p->inuse);
2772                         continue;
2773                 }
2774                 nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
2775                 if (p->shift == 0 || p->ptr[i] == NULL)
2776                         return nr;
2777                 p = p->ptr[i];
2778         }
2779 }
2780
2781 static void cardmap_destroy(struct cardmap **pmap)
2782 {
2783         struct cardmap *p, *np;
2784         int i;
2785
2786         for (p = *pmap; p != NULL; p = np) {
2787                 if (p->shift != 0) {
2788                         for (i = 0; i < CARDMAP_WIDTH; ++i)
2789                                 if (p->ptr[i] != NULL)
2790                                         break;
2791                         if (i < CARDMAP_WIDTH) {
2792                                 np = p->ptr[i];
2793                                 p->ptr[i] = NULL;
2794                                 continue;
2795                         }
2796                 }
2797                 np = p->parent;
2798                 kfree(p);
2799         }
2800         *pmap = NULL;
2801 }
2802
2803 /* Module/initialization stuff */
2804
2805 module_init(ppp_init);
2806 module_exit(ppp_cleanup);
2807
2808 EXPORT_SYMBOL(ppp_register_channel);
2809 EXPORT_SYMBOL(ppp_unregister_channel);
2810 EXPORT_SYMBOL(ppp_channel_index);
2811 EXPORT_SYMBOL(ppp_unit_number);
2812 EXPORT_SYMBOL(ppp_input);
2813 EXPORT_SYMBOL(ppp_input_error);
2814 EXPORT_SYMBOL(ppp_output_wakeup);
2815 EXPORT_SYMBOL(ppp_register_compressor);
2816 EXPORT_SYMBOL(ppp_unregister_compressor);
2817 MODULE_LICENSE("GPL");
2818 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2819 MODULE_ALIAS("/dev/ppp");