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/config.h>
  26 #include <linux/module.h>
  27 #include <linux/kernel.h>
  28 #include <linux/kmod.h>
  29 #include <linux/init.h>
  30 #include <linux/list.h>
  31 #include <linux/devfs_fs_kernel.h>
  32 #include <linux/netdevice.h>
  33 #include <linux/poll.h>
  34 #include <linux/ppp_defs.h>
  35 #include <linux/filter.h>
  36 #include <linux/if_ppp.h>
  37 #include <linux/ppp_channel.h>
  38 #include <linux/ppp-comp.h>
  39 #include <linux/skbuff.h>
  40 #include <linux/rtnetlink.h>
  41 #include <linux/if_arp.h>
  42 #include <linux/ip.h>
  43 #include <linux/tcp.h>
  44 #include <linux/spinlock.h>
  45 #include <linux/smp_lock.h>
  46 #include <linux/rwsem.h>
  47 #include <linux/stddef.h>
  48 #include <linux/device.h>
  49 #include <linux/mutex.h>
  50 #include <net/slhc_vj.h>
  51 #include <asm/atomic.h>
  52
  53 #define PPP_VERSION     "2.4.2"
  54
  55 /*
  56  * Network protocols we support.
  57  */
  58 #define NP_IP   0               /* Internet Protocol V4 */
  59 #define NP_IPV6 1               /* Internet Protocol V6 */
  60 #define NP_IPX  2               /* IPX protocol */
  61 #define NP_AT   3               /* Appletalk protocol */
  62 #define NP_MPLS_UC 4            /* MPLS unicast */
  63 #define NP_MPLS_MC 5            /* MPLS multicast */
  64 #define NUM_NP  6               /* Number of NPs. */
  65
  66 #define MPHDRLEN        6       /* multilink protocol header length */
  67 #define MPHDRLEN_SSN    4       /* ditto with short sequence numbers */
  68 #define MIN_FRAG_SIZE   64
  69
  70 /*
  71  * An instance of /dev/ppp can be associated with either a ppp
  72  * interface unit or a ppp channel.  In both cases, file->private_data
  73  * points to one of these.
  74  */
  75 struct ppp_file {
  76         enum {
  77                 INTERFACE=1, CHANNEL
  78         }               kind;
  79         struct sk_buff_head xq;         /* pppd transmit queue */
  80         struct sk_buff_head rq;         /* receive queue for pppd */
  81         wait_queue_head_t rwait;        /* for poll on reading /dev/ppp */
  82         atomic_t        refcnt;         /* # refs (incl /dev/ppp attached) */
  83         int             hdrlen;         /* space to leave for headers */
  84         int             index;          /* interface unit / channel number */
  85         int             dead;           /* unit/channel has been shut down */
  86 };
  87
  88 #define PF_TO_X(pf, X)          ((X *)((char *)(pf) - offsetof(X, file)))
  89
  90 #define PF_TO_PPP(pf)           PF_TO_X(pf, struct ppp)
  91 #define PF_TO_CHANNEL(pf)       PF_TO_X(pf, struct channel)
  92
  93 #define ROUNDUP(n, x)           (((n) + (x) - 1) / (x))
  94
  95 /*
  96  * Data structure describing one ppp unit.
  97  * A ppp unit corresponds to a ppp network interface device
  98  * and represents a multilink bundle.
  99  * It can have 0 or more ppp channels connected to it.
 100  */
 101 struct ppp {
 102         struct ppp_file file;           /* stuff for read/write/poll 0 */
 103         struct file     *owner;         /* file that owns this unit 48 */
 104         struct list_head channels;      /* list of attached channels 4c */
 105         int             n_channels;     /* how many channels are attached 54 */
 106         spinlock_t      rlock;          /* lock for receive side 58 */
 107         spinlock_t      wlock;          /* lock for transmit side 5c */
 108         int             mru;            /* max receive unit 60 */
 109         unsigned int    flags;          /* control bits 64 */
 110         unsigned int    xstate;         /* transmit state bits 68 */
 111         unsigned int    rstate;         /* receive state bits 6c */
 112         int             debug;          /* debug flags 70 */
 113         struct slcompress *vj;          /* state for VJ header compression */
 114         enum NPmode     npmode[NUM_NP]; /* what to do with each net proto 78 */
 115         struct sk_buff  *xmit_pending;  /* a packet ready to go out 88 */
 116         struct compressor *xcomp;       /* transmit packet compressor 8c */
 117         void            *xc_state;      /* its internal state 90 */
 118         struct compressor *rcomp;       /* receive decompressor 94 */
 119         void            *rc_state;      /* its internal state 98 */
 120         unsigned long   last_xmit;      /* jiffies when last pkt sent 9c */
 121         unsigned long   last_recv;      /* jiffies when last pkt rcvd a0 */
 122         struct net_device *dev;         /* network interface device a4 */
 123 #ifdef CONFIG_PPP_MULTILINK
 124         int             nxchan;         /* next channel to send something on */
 125         u32             nxseq;          /* next sequence number to send */
 126         int             mrru;           /* MP: max reconst. receive unit */
 127         u32             nextseq;        /* MP: seq no of next packet */
 128         u32             minseq;         /* MP: min of most recent seqnos */
 129         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
 130 #endif /* CONFIG_PPP_MULTILINK */
 131         struct net_device_stats stats;  /* statistics */
 132 #ifdef CONFIG_PPP_FILTER
 133         struct sock_filter *pass_filter;        /* filter for packets to pass */
 134         struct sock_filter *active_filter;/* filter for pkts to reset idle */
 135         unsigned pass_len, active_len;
 136 #endif /* CONFIG_PPP_FILTER */
 137 };
 138
 139 /*
 140  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
 141  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
 142  * SC_MUST_COMP
 143  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
 144  * Bits in xstate: SC_COMP_RUN
 145  */
 146 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
 147                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
 148                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
 149
 150 /*
 151  * Private data structure for each channel.
 152  * This includes the data structure used for multilink.
 153  */
 154 struct channel {
 155         struct ppp_file file;           /* stuff for read/write/poll */
 156         struct list_head list;          /* link in all/new_channels list */
 157         struct ppp_channel *chan;       /* public channel data structure */
 158         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
 159         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
 160         struct ppp      *ppp;           /* ppp unit we're connected to */
 161         struct list_head clist;         /* link in list of channels per unit */
 162         rwlock_t        upl;            /* protects `ppp' */
 163 #ifdef CONFIG_PPP_MULTILINK
 164         u8              avail;          /* flag used in multilink stuff */
 165         u8              had_frag;       /* >= 1 fragments have been sent */
 166         u32             lastseq;        /* MP: last sequence # received */
 167 #endif /* CONFIG_PPP_MULTILINK */
 168 };
 169
 170 /*
 171  * SMP locking issues:
 172  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
 173  * list and the ppp.n_channels field, you need to take both locks
 174  * before you modify them.
 175  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
 176  * channel.downl.
 177  */
 178
 179 /*
 180  * A cardmap represents a mapping from unsigned integers to pointers,
 181  * and provides a fast "find lowest unused number" operation.
 182  * It uses a broad (32-way) tree with a bitmap at each level.
 183  * It is designed to be space-efficient for small numbers of entries
 184  * and time-efficient for large numbers of entries.
 185  */
 186 #define CARDMAP_ORDER   5
 187 #define CARDMAP_WIDTH   (1U << CARDMAP_ORDER)
 188 #define CARDMAP_MASK    (CARDMAP_WIDTH - 1)
 189
 190 struct cardmap {
 191         int shift;
 192         unsigned long inuse;
 193         struct cardmap *parent;
 194         void *ptr[CARDMAP_WIDTH];
 195 };
 196 static void *cardmap_get(struct cardmap *map, unsigned int nr);
 197 static void cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
 198 static unsigned int cardmap_find_first_free(struct cardmap *map);
 199 static void cardmap_destroy(struct cardmap **map);
 200
 201 /*
 202  * all_ppp_mutex protects the all_ppp_units mapping.
 203  * It also ensures that finding a ppp unit in the all_ppp_units map
 204  * and updating its file.refcnt field is atomic.
 205  */
 206 static DEFINE_MUTEX(all_ppp_mutex);
 207 static struct cardmap *all_ppp_units;
 208 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 209
 210 /*
 211  * all_channels_lock protects all_channels and last_channel_index,
 212  * and the atomicity of find a channel and updating its file.refcnt
 213  * field.
 214  */
 215 static DEFINE_SPINLOCK(all_channels_lock);
 216 static LIST_HEAD(all_channels);
 217 static LIST_HEAD(new_channels);
 218 static int last_channel_index;
 219 static atomic_t channel_count = ATOMIC_INIT(0);
 220
 221 /* Get the PPP protocol number from a skb */
 222 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
 223
 224 /* We limit the length of ppp->file.rq to this (arbitrary) value */
 225 #define PPP_MAX_RQLEN   32
 226
 227 /*
 228  * Maximum number of multilink fragments queued up.
 229  * This has to be large enough to cope with the maximum latency of
 230  * the slowest channel relative to the others.  Strictly it should
 231  * depend on the number of channels and their characteristics.
 232  */
 233 #define PPP_MP_MAX_QLEN 128
 234
 235 /* Multilink header bits. */
 236 #define B       0x80            /* this fragment begins a packet */
 237 #define E       0x40            /* this fragment ends a packet */
 238
 239 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
 240 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
 241 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
 242
 243 /* Prototypes. */
 244 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 245                                 unsigned int cmd, unsigned long arg);
 246 static void ppp_xmit_process(struct ppp *ppp);
 247 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
 248 static void ppp_push(struct ppp *ppp);
 249 static void ppp_channel_push(struct channel *pch);
 250 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
 251                               struct channel *pch);
 252 static void ppp_receive_error(struct ppp *ppp);
 253 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
 254 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
 255                                             struct sk_buff *skb);
 256 #ifdef CONFIG_PPP_MULTILINK
 257 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
 258                                 struct channel *pch);
 259 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
 260 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
 261 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
 262 #endif /* CONFIG_PPP_MULTILINK */
 263 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
 264 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
 265 static void ppp_ccp_closed(struct ppp *ppp);
 266 static struct compressor *find_compressor(int type);
 267 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
 268 static struct ppp *ppp_create_interface(int unit, int *retp);
 269 static void init_ppp_file(struct ppp_file *pf, int kind);
 270 static void ppp_shutdown_interface(struct ppp *ppp);
 271 static void ppp_destroy_interface(struct ppp *ppp);
 272 static struct ppp *ppp_find_unit(int unit);
 273 static struct channel *ppp_find_channel(int unit);
 274 static int ppp_connect_channel(struct channel *pch, int unit);
 275 static int ppp_disconnect_channel(struct channel *pch);
 276 static void ppp_destroy_channel(struct channel *pch);
 277
 278 static struct class *ppp_class;
 279
 280 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
 281 static inline int proto_to_npindex(int proto)
 282 {
 283         switch (proto) {
 284         case PPP_IP:
 285                 return NP_IP;
 286         case PPP_IPV6:
 287                 return NP_IPV6;
 288         case PPP_IPX:
 289                 return NP_IPX;
 290         case PPP_AT:
 291                 return NP_AT;
 292         case PPP_MPLS_UC:
 293                 return NP_MPLS_UC;
 294         case PPP_MPLS_MC:
 295                 return NP_MPLS_MC;
 296         }
 297         return -EINVAL;
 298 }
 299
 300 /* Translates an NP index into a PPP protocol number */
 301 static const int npindex_to_proto[NUM_NP] = {
 302         PPP_IP,
 303         PPP_IPV6,
 304         PPP_IPX,
 305         PPP_AT,
 306         PPP_MPLS_UC,
 307         PPP_MPLS_MC,
 308 };
 309
 310 /* Translates an ethertype into an NP index */
 311 static inline int ethertype_to_npindex(int ethertype)
 312 {
 313         switch (ethertype) {
 314         case ETH_P_IP:
 315                 return NP_IP;
 316         case ETH_P_IPV6:
 317                 return NP_IPV6;
 318         case ETH_P_IPX:
 319                 return NP_IPX;
 320         case ETH_P_PPPTALK:
 321         case ETH_P_ATALK:
 322                 return NP_AT;
 323         case ETH_P_MPLS_UC:
 324                 return NP_MPLS_UC;
 325         case ETH_P_MPLS_MC:
 326                 return NP_MPLS_MC;
 327         }
 328         return -1;
 329 }
 330
 331 /* Translates an NP index into an ethertype */
 332 static const int npindex_to_ethertype[NUM_NP] = {
 333         ETH_P_IP,
 334         ETH_P_IPV6,
 335         ETH_P_IPX,
 336         ETH_P_PPPTALK,
 337         ETH_P_MPLS_UC,
 338         ETH_P_MPLS_MC,
 339 };
 340
 341 /*
 342  * Locking shorthand.
 343  */
 344 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
 345 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
 346 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
 347 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
 348 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
 349                                      ppp_recv_lock(ppp); } while (0)
 350 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
 351                                      ppp_xmit_unlock(ppp); } while (0)
 352
 353 /*
 354  * /dev/ppp device routines.
 355  * The /dev/ppp device is used by pppd to control the ppp unit.
 356  * It supports the read, write, ioctl and poll functions.
 357  * Open instances of /dev/ppp can be in one of three states:
 358  * unattached, attached to a ppp unit, or attached to a ppp channel.
 359  */
 360 static int ppp_open(struct inode *inode, struct file *file)
 361 {
 362         /*
 363          * This could (should?) be enforced by the permissions on /dev/ppp.
 364          */
 365         if (!capable(CAP_NET_ADMIN))
 366                 return -EPERM;
 367         return 0;
 368 }
 369
 370 static int ppp_release(struct inode *inode, struct file *file)
 371 {
 372         struct ppp_file *pf = file->private_data;
 373         struct ppp *ppp;
 374
 375         if (pf != 0) {
 376                 file->private_data = NULL;
 377                 if (pf->kind == INTERFACE) {
 378                         ppp = PF_TO_PPP(pf);
 379                         if (file == ppp->owner)
 380                                 ppp_shutdown_interface(ppp);
 381                 }
 382                 if (atomic_dec_and_test(&pf->refcnt)) {
 383                         switch (pf->kind) {
 384                         case INTERFACE:
 385                                 ppp_destroy_interface(PF_TO_PPP(pf));
 386                                 break;
 387                         case CHANNEL:
 388                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
 389                                 break;
 390                         }
 391                 }
 392         }
 393         return 0;
 394 }
 395
 396 static ssize_t ppp_read(struct file *file, char __user *buf,
 397                         size_t count, loff_t *ppos)
 398 {
 399         struct ppp_file *pf = file->private_data;
 400         DECLARE_WAITQUEUE(wait, current);
 401         ssize_t ret;
 402         struct sk_buff *skb = NULL;
 403
 404         ret = count;
 405
 406         if (pf == 0)
 407                 return -ENXIO;
 408         add_wait_queue(&pf->rwait, &wait);
 409         for (;;) {
 410                 set_current_state(TASK_INTERRUPTIBLE);
 411                 skb = skb_dequeue(&pf->rq);
 412                 if (skb)
 413                         break;
 414                 ret = 0;
 415                 if (pf->dead)
 416                         break;
 417                 if (pf->kind == INTERFACE) {
 418                         /*
 419                          * Return 0 (EOF) on an interface that has no
 420                          * channels connected, unless it is looping
 421                          * network traffic (demand mode).
 422                          */
 423                         struct ppp *ppp = PF_TO_PPP(pf);
 424                         if (ppp->n_channels == 0
 425                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 426                                 break;
 427                 }
 428                 ret = -EAGAIN;
 429                 if (file->f_flags & O_NONBLOCK)
 430                         break;
 431                 ret = -ERESTARTSYS;
 432                 if (signal_pending(current))
 433                         break;
 434                 schedule();
 435         }
 436         set_current_state(TASK_RUNNING);
 437         remove_wait_queue(&pf->rwait, &wait);
 438
 439         if (skb == 0)
 440                 goto out;
 441
 442         ret = -EOVERFLOW;
 443         if (skb->len > count)
 444                 goto outf;
 445         ret = -EFAULT;
 446         if (copy_to_user(buf, skb->data, skb->len))
 447                 goto outf;
 448         ret = skb->len;
 449
 450  outf:
 451         kfree_skb(skb);
 452  out:
 453         return ret;
 454 }
 455
 456 static ssize_t ppp_write(struct file *file, const char __user *buf,
 457                          size_t count, loff_t *ppos)
 458 {
 459         struct ppp_file *pf = file->private_data;
 460         struct sk_buff *skb;
 461         ssize_t ret;
 462
 463         if (pf == 0)
 464                 return -ENXIO;
 465         ret = -ENOMEM;
 466         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
 467         if (skb == 0)
 468                 goto out;
 469         skb_reserve(skb, pf->hdrlen);
 470         ret = -EFAULT;
 471         if (copy_from_user(skb_put(skb, count), buf, count)) {
 472                 kfree_skb(skb);
 473                 goto out;
 474         }
 475
 476         skb_queue_tail(&pf->xq, skb);
 477
 478         switch (pf->kind) {
 479         case INTERFACE:
 480                 ppp_xmit_process(PF_TO_PPP(pf));
 481                 break;
 482         case CHANNEL:
 483                 ppp_channel_push(PF_TO_CHANNEL(pf));
 484                 break;
 485         }
 486
 487         ret = count;
 488
 489  out:
 490         return ret;
 491 }
 492
 493 /* No kernel lock - fine */
 494 static unsigned int ppp_poll(struct file *file, poll_table *wait)
 495 {
 496         struct ppp_file *pf = file->private_data;
 497         unsigned int mask;
 498
 499         if (pf == 0)
 500                 return 0;
 501         poll_wait(file, &pf->rwait, wait);
 502         mask = POLLOUT | POLLWRNORM;
 503         if (skb_peek(&pf->rq) != 0)
 504                 mask |= POLLIN | POLLRDNORM;
 505         if (pf->dead)
 506                 mask |= POLLHUP;
 507         else if (pf->kind == INTERFACE) {
 508                 /* see comment in ppp_read */
 509                 struct ppp *ppp = PF_TO_PPP(pf);
 510                 if (ppp->n_channels == 0
 511                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 512                         mask |= POLLIN | POLLRDNORM;
 513         }
 514
 515         return mask;
 516 }
 517
 518 #ifdef CONFIG_PPP_FILTER
 519 static int get_filter(void __user *arg, struct sock_filter **p)
 520 {
 521         struct sock_fprog uprog;
 522         struct sock_filter *code = NULL;
 523         int len, err;
 524
 525         if (copy_from_user(&uprog, arg, sizeof(uprog)))
 526                 return -EFAULT;
 527
 528         if (!uprog.len) {
 529                 *p = NULL;
 530                 return 0;
 531         }
 532
 533         len = uprog.len * sizeof(struct sock_filter);
 534         code = kmalloc(len, GFP_KERNEL);
 535         if (code == NULL)
 536                 return -ENOMEM;
 537
 538         if (copy_from_user(code, uprog.filter, len)) {
 539                 kfree(code);
 540                 return -EFAULT;
 541         }
 542
 543         err = sk_chk_filter(code, uprog.len);
 544         if (err) {
 545                 kfree(code);
 546                 return err;
 547         }
 548
 549         *p = code;
 550         return uprog.len;
 551 }
 552 #endif /* CONFIG_PPP_FILTER */
 553
 554 static int ppp_ioctl(struct inode *inode, struct file *file,
 555                      unsigned int cmd, unsigned long arg)
 556 {
 557         struct ppp_file *pf = file->private_data;
 558         struct ppp *ppp;
 559         int err = -EFAULT, val, val2, i;
 560         struct ppp_idle idle;
 561         struct npioctl npi;
 562         int unit, cflags;
 563         struct slcompress *vj;
 564         void __user *argp = (void __user *)arg;
 565         int __user *p = argp;
 566
 567         if (pf == 0)
 568                 return ppp_unattached_ioctl(pf, file, cmd, arg);
 569
 570         if (cmd == PPPIOCDETACH) {
 571                 /*
 572                  * We have to be careful here... if the file descriptor
 573                  * has been dup'd, we could have another process in the
 574                  * middle of a poll using the same file *, so we had
 575                  * better not free the interface data structures -
 576                  * instead we fail the ioctl.  Even in this case, we
 577                  * shut down the interface if we are the owner of it.
 578                  * Actually, we should get rid of PPPIOCDETACH, userland
 579                  * (i.e. pppd) could achieve the same effect by closing
 580                  * this fd and reopening /dev/ppp.
 581                  */
 582                 err = -EINVAL;
 583                 if (pf->kind == INTERFACE) {
 584                         ppp = PF_TO_PPP(pf);
 585                         if (file == ppp->owner)
 586                                 ppp_shutdown_interface(ppp);
 587                 }
 588                 if (atomic_read(&file->f_count) <= 2) {
 589                         ppp_release(inode, file);
 590                         err = 0;
 591                 } else
 592                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%d\n",
 593                                atomic_read(&file->f_count));
 594                 return err;
 595         }
 596
 597         if (pf->kind == CHANNEL) {
 598                 struct channel *pch = PF_TO_CHANNEL(pf);
 599                 struct ppp_channel *chan;
 600
 601                 switch (cmd) {
 602                 case PPPIOCCONNECT:
 603                         if (get_user(unit, p))
 604                                 break;
 605                         err = ppp_connect_channel(pch, unit);
 606                         break;
 607
 608                 case PPPIOCDISCONN:
 609                         err = ppp_disconnect_channel(pch);
 610                         break;
 611
 612                 default:
 613                         down_read(&pch->chan_sem);
 614                         chan = pch->chan;
 615                         err = -ENOTTY;
 616                         if (chan && chan->ops->ioctl)
 617                                 err = chan->ops->ioctl(chan, cmd, arg);
 618                         up_read(&pch->chan_sem);
 619                 }
 620                 return err;
 621         }
 622
 623         if (pf->kind != INTERFACE) {
 624                 /* can't happen */
 625                 printk(KERN_ERR "PPP: not interface or channel??\n");
 626                 return -EINVAL;
 627         }
 628
 629         ppp = PF_TO_PPP(pf);
 630         switch (cmd) {
 631         case PPPIOCSMRU:
 632                 if (get_user(val, p))
 633                         break;
 634                 ppp->mru = val;
 635                 err = 0;
 636                 break;
 637
 638         case PPPIOCSFLAGS:
 639                 if (get_user(val, p))
 640                         break;
 641                 ppp_lock(ppp);
 642                 cflags = ppp->flags & ~val;
 643                 ppp->flags = val & SC_FLAG_BITS;
 644                 ppp_unlock(ppp);
 645                 if (cflags & SC_CCP_OPEN)
 646                         ppp_ccp_closed(ppp);
 647                 err = 0;
 648                 break;
 649
 650         case PPPIOCGFLAGS:
 651                 val = ppp->flags | ppp->xstate | ppp->rstate;
 652                 if (put_user(val, p))
 653                         break;
 654                 err = 0;
 655                 break;
 656
 657         case PPPIOCSCOMPRESS:
 658                 err = ppp_set_compress(ppp, arg);
 659                 break;
 660
 661         case PPPIOCGUNIT:
 662                 if (put_user(ppp->file.index, p))
 663                         break;
 664                 err = 0;
 665                 break;
 666
 667         case PPPIOCSDEBUG:
 668                 if (get_user(val, p))
 669                         break;
 670                 ppp->debug = val;
 671                 err = 0;
 672                 break;
 673
 674         case PPPIOCGDEBUG:
 675                 if (put_user(ppp->debug, p))
 676                         break;
 677                 err = 0;
 678                 break;
 679
 680         case PPPIOCGIDLE:
 681                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 682                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
 683                 if (copy_to_user(argp, &idle, sizeof(idle)))
 684                         break;
 685                 err = 0;
 686                 break;
 687
 688         case PPPIOCSMAXCID:
 689                 if (get_user(val, p))
 690                         break;
 691                 val2 = 15;
 692                 if ((val >> 16) != 0) {
 693                         val2 = val >> 16;
 694                         val &= 0xffff;
 695                 }
 696                 vj = slhc_init(val2+1, val+1);
 697                 if (vj == 0) {
 698                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
 699                         err = -ENOMEM;
 700                         break;
 701                 }
 702                 ppp_lock(ppp);
 703                 if (ppp->vj != 0)
 704                         slhc_free(ppp->vj);
 705                 ppp->vj = vj;
 706                 ppp_unlock(ppp);
 707                 err = 0;
 708                 break;
 709
 710         case PPPIOCGNPMODE:
 711         case PPPIOCSNPMODE:
 712                 if (copy_from_user(&npi, argp, sizeof(npi)))
 713                         break;
 714                 err = proto_to_npindex(npi.protocol);
 715                 if (err < 0)
 716                         break;
 717                 i = err;
 718                 if (cmd == PPPIOCGNPMODE) {
 719                         err = -EFAULT;
 720                         npi.mode = ppp->npmode[i];
 721                         if (copy_to_user(argp, &npi, sizeof(npi)))
 722                                 break;
 723                 } else {
 724                         ppp->npmode[i] = npi.mode;
 725                         /* we may be able to transmit more packets now (??) */
 726                         netif_wake_queue(ppp->dev);
 727                 }
 728                 err = 0;
 729                 break;
 730
 731 #ifdef CONFIG_PPP_FILTER
 732         case PPPIOCSPASS:
 733         {
 734                 struct sock_filter *code;
 735                 err = get_filter(argp, &code);
 736                 if (err >= 0) {
 737                         ppp_lock(ppp);
 738                         kfree(ppp->pass_filter);
 739                         ppp->pass_filter = code;
 740                         ppp->pass_len = err;
 741                         ppp_unlock(ppp);
 742                         err = 0;
 743                 }
 744                 break;
 745         }
 746         case PPPIOCSACTIVE:
 747         {
 748                 struct sock_filter *code;
 749                 err = get_filter(argp, &code);
 750                 if (err >= 0) {
 751                         ppp_lock(ppp);
 752                         kfree(ppp->active_filter);
 753                         ppp->active_filter = code;
 754                         ppp->active_len = err;
 755                         ppp_unlock(ppp);
 756                         err = 0;
 757                 }
 758                 break;
 759         }
 760 #endif /* CONFIG_PPP_FILTER */
 761
 762 #ifdef CONFIG_PPP_MULTILINK
 763         case PPPIOCSMRRU:
 764                 if (get_user(val, p))
 765                         break;
 766                 ppp_recv_lock(ppp);
 767                 ppp->mrru = val;
 768                 ppp_recv_unlock(ppp);
 769                 err = 0;
 770                 break;
 771 #endif /* CONFIG_PPP_MULTILINK */
 772
 773         default:
 774                 err = -ENOTTY;
 775         }
 776
 777         return err;
 778 }
 779
 780 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 781                                 unsigned int cmd, unsigned long arg)
 782 {
 783         int unit, err = -EFAULT;
 784         struct ppp *ppp;
 785         struct channel *chan;
 786         int __user *p = (int __user *)arg;
 787
 788         switch (cmd) {
 789         case PPPIOCNEWUNIT:
 790                 /* Create a new ppp unit */
 791                 if (get_user(unit, p))
 792                         break;
 793                 ppp = ppp_create_interface(unit, &err);
 794                 if (ppp == 0)
 795                         break;
 796                 file->private_data = &ppp->file;
 797                 ppp->owner = file;
 798                 err = -EFAULT;
 799                 if (put_user(ppp->file.index, p))
 800                         break;
 801                 err = 0;
 802                 break;
 803
 804         case PPPIOCATTACH:
 805                 /* Attach to an existing ppp unit */
 806                 if (get_user(unit, p))
 807                         break;
 808                 mutex_lock(&all_ppp_mutex);
 809                 err = -ENXIO;
 810                 ppp = ppp_find_unit(unit);
 811                 if (ppp != 0) {
 812                         atomic_inc(&ppp->file.refcnt);
 813                         file->private_data = &ppp->file;
 814                         err = 0;
 815                 }
 816                 mutex_unlock(&all_ppp_mutex);
 817                 break;
 818
 819         case PPPIOCATTCHAN:
 820                 if (get_user(unit, p))
 821                         break;
 822                 spin_lock_bh(&all_channels_lock);
 823                 err = -ENXIO;
 824                 chan = ppp_find_channel(unit);
 825                 if (chan != 0) {
 826                         atomic_inc(&chan->file.refcnt);
 827                         file->private_data = &chan->file;
 828                         err = 0;
 829                 }
 830                 spin_unlock_bh(&all_channels_lock);
 831                 break;
 832
 833         default:
 834                 err = -ENOTTY;
 835         }
 836         return err;
 837 }
 838
 839 static struct file_operations ppp_device_fops = {
 840         .owner          = THIS_MODULE,
 841         .read           = ppp_read,
 842         .write          = ppp_write,
 843         .poll           = ppp_poll,
 844         .ioctl          = ppp_ioctl,
 845         .open           = ppp_open,
 846         .release        = ppp_release
 847 };
 848
 849 #define PPP_MAJOR       108
 850
 851 /* Called at boot time if ppp is compiled into the kernel,
 852    or at module load time (from init_module) if compiled as a module. */
 853 static int __init ppp_init(void)
 854 {
 855         int err;
 856
 857         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
 858         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
 859         if (!err) {
 860                 ppp_class = class_create(THIS_MODULE, "ppp");
 861                 if (IS_ERR(ppp_class)) {
 862                         err = PTR_ERR(ppp_class);
 863                         goto out_chrdev;
 864                 }
 865                 class_device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL, "ppp");
 866                 err = devfs_mk_cdev(MKDEV(PPP_MAJOR, 0),
 867                                 S_IFCHR|S_IRUSR|S_IWUSR, "ppp");
 868                 if (err)
 869                         goto out_class;
 870         }
 871
 872 out:
 873         if (err)
 874                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
 875         return err;
 876
 877 out_class:
 878         class_device_destroy(ppp_class, MKDEV(PPP_MAJOR,0));
 879         class_destroy(ppp_class);
 880 out_chrdev:
 881         unregister_chrdev(PPP_MAJOR, "ppp");
 882         goto out;
 883 }
 884
 885 /*
 886  * Network interface unit routines.
 887  */
 888 static int
 889 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 890 {
 891         struct ppp *ppp = (struct ppp *) dev->priv;
 892         int npi, proto;
 893         unsigned char *pp;
 894
 895         npi = ethertype_to_npindex(ntohs(skb->protocol));
 896         if (npi < 0)
 897                 goto outf;
 898
 899         /* Drop, accept or reject the packet */
 900         switch (ppp->npmode[npi]) {
 901         case NPMODE_PASS:
 902                 break;
 903         case NPMODE_QUEUE:
 904                 /* it would be nice to have a way to tell the network
 905                    system to queue this one up for later. */
 906                 goto outf;
 907         case NPMODE_DROP:
 908         case NPMODE_ERROR:
 909                 goto outf;
 910         }
 911
 912         /* Put the 2-byte PPP protocol number on the front,
 913            making sure there is room for the address and control fields. */
 914         if (skb_headroom(skb) < PPP_HDRLEN) {
 915                 struct sk_buff *ns;
 916
 917                 ns = alloc_skb(skb->len + dev->hard_header_len, GFP_ATOMIC);
 918                 if (ns == 0)
 919                         goto outf;
 920                 skb_reserve(ns, dev->hard_header_len);
 921                 skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
 922                 kfree_skb(skb);
 923                 skb = ns;
 924         }
 925         pp = skb_push(skb, 2);
 926         proto = npindex_to_proto[npi];
 927         pp[0] = proto >> 8;
 928         pp[1] = proto;
 929
 930         netif_stop_queue(dev);
 931         skb_queue_tail(&ppp->file.xq, skb);
 932         ppp_xmit_process(ppp);
 933         return 0;
 934
 935  outf:
 936         kfree_skb(skb);
 937         ++ppp->stats.tx_dropped;
 938         return 0;
 939 }
 940
 941 static struct net_device_stats *
 942 ppp_net_stats(struct net_device *dev)
 943 {
 944         struct ppp *ppp = (struct ppp *) dev->priv;
 945
 946         return &ppp->stats;
 947 }
 948
 949 static int
 950 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 951 {
 952         struct ppp *ppp = dev->priv;
 953         int err = -EFAULT;
 954         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
 955         struct ppp_stats stats;
 956         struct ppp_comp_stats cstats;
 957         char *vers;
 958
 959         switch (cmd) {
 960         case SIOCGPPPSTATS:
 961                 ppp_get_stats(ppp, &stats);
 962                 if (copy_to_user(addr, &stats, sizeof(stats)))
 963                         break;
 964                 err = 0;
 965                 break;
 966
 967         case SIOCGPPPCSTATS:
 968                 memset(&cstats, 0, sizeof(cstats));
 969                 if (ppp->xc_state != 0)
 970                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
 971                 if (ppp->rc_state != 0)
 972                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
 973                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
 974                         break;
 975                 err = 0;
 976                 break;
 977
 978         case SIOCGPPPVER:
 979                 vers = PPP_VERSION;
 980                 if (copy_to_user(addr, vers, strlen(vers) + 1))
 981                         break;
 982                 err = 0;
 983                 break;
 984
 985         default:
 986                 err = -EINVAL;
 987         }
 988
 989         return err;
 990 }
 991
 992 static void ppp_setup(struct net_device *dev)
 993 {
 994         dev->hard_header_len = PPP_HDRLEN;
 995         dev->mtu = PPP_MTU;
 996         dev->addr_len = 0;
 997         dev->tx_queue_len = 3;
 998         dev->type = ARPHRD_PPP;
 999         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1000 }
1001
1002 /*
1003  * Transmit-side routines.
1004  */
1005
1006 /*
1007  * Called to do any work queued up on the transmit side
1008  * that can now be done.
1009  */
1010 static void
1011 ppp_xmit_process(struct ppp *ppp)
1012 {
1013         struct sk_buff *skb;
1014
1015         ppp_xmit_lock(ppp);
1016         if (ppp->dev != 0) {
1017                 ppp_push(ppp);
1018                 while (ppp->xmit_pending == 0
1019                        && (skb = skb_dequeue(&ppp->file.xq)) != 0)
1020                         ppp_send_frame(ppp, skb);
1021                 /* If there's no work left to do, tell the core net
1022                    code that we can accept some more. */
1023                 if (ppp->xmit_pending == 0 && skb_peek(&ppp->file.xq) == 0)
1024                         netif_wake_queue(ppp->dev);
1025         }
1026         ppp_xmit_unlock(ppp);
1027 }
1028
1029 static inline struct sk_buff *
1030 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1031 {
1032         struct sk_buff *new_skb;
1033         int len;
1034         int new_skb_size = ppp->dev->mtu +
1035                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1036         int compressor_skb_size = ppp->dev->mtu +
1037                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1038         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1039         if (!new_skb) {
1040                 if (net_ratelimit())
1041                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1042                 return NULL;
1043         }
1044         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1045                 skb_reserve(new_skb,
1046                             ppp->dev->hard_header_len - PPP_HDRLEN);
1047
1048         /* compressor still expects A/C bytes in hdr */
1049         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1050                                    new_skb->data, skb->len + 2,
1051                                    compressor_skb_size);
1052         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1053                 kfree_skb(skb);
1054                 skb = new_skb;
1055                 skb_put(skb, len);
1056                 skb_pull(skb, 2);       /* pull off A/C bytes */
1057         } else if (len == 0) {
1058                 /* didn't compress, or CCP not up yet */
1059                 kfree_skb(new_skb);
1060                 new_skb = skb;
1061         } else {
1062                 /*
1063                  * (len < 0)
1064                  * MPPE requires that we do not send unencrypted
1065                  * frames.  The compressor will return -1 if we
1066                  * should drop the frame.  We cannot simply test
1067                  * the compress_proto because MPPE and MPPC share
1068                  * the same number.
1069                  */
1070                 if (net_ratelimit())
1071                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1072                 kfree_skb(skb);
1073                 kfree_skb(new_skb);
1074                 new_skb = NULL;
1075         }
1076         return new_skb;
1077 }
1078
1079 /*
1080  * Compress and send a frame.
1081  * The caller should have locked the xmit path,
1082  * and xmit_pending should be 0.
1083  */
1084 static void
1085 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1086 {
1087         int proto = PPP_PROTO(skb);
1088         struct sk_buff *new_skb;
1089         int len;
1090         unsigned char *cp;
1091
1092         if (proto < 0x8000) {
1093 #ifdef CONFIG_PPP_FILTER
1094                 /* check if we should pass this packet */
1095                 /* the filter instructions are constructed assuming
1096                    a four-byte PPP header on each packet */
1097                 *skb_push(skb, 2) = 1;
1098                 if (ppp->pass_filter
1099                     && sk_run_filter(skb, ppp->pass_filter,
1100                                      ppp->pass_len) == 0) {
1101                         if (ppp->debug & 1)
1102                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1103                         kfree_skb(skb);
1104                         return;
1105                 }
1106                 /* if this packet passes the active filter, record the time */
1107                 if (!(ppp->active_filter
1108                       && sk_run_filter(skb, ppp->active_filter,
1109                                        ppp->active_len) == 0))
1110                         ppp->last_xmit = jiffies;
1111                 skb_pull(skb, 2);
1112 #else
1113                 /* for data packets, record the time */
1114                 ppp->last_xmit = jiffies;
1115 #endif /* CONFIG_PPP_FILTER */
1116         }
1117
1118         ++ppp->stats.tx_packets;
1119         ppp->stats.tx_bytes += skb->len - 2;
1120
1121         switch (proto) {
1122         case PPP_IP:
1123                 if (ppp->vj == 0 || (ppp->flags & SC_COMP_TCP) == 0)
1124                         break;
1125                 /* try to do VJ TCP header compression */
1126                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1127                                     GFP_ATOMIC);
1128                 if (new_skb == 0) {
1129                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1130                         goto drop;
1131                 }
1132                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1133                 cp = skb->data + 2;
1134                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1135                                     new_skb->data + 2, &cp,
1136                                     !(ppp->flags & SC_NO_TCP_CCID));
1137                 if (cp == skb->data + 2) {
1138                         /* didn't compress */
1139                         kfree_skb(new_skb);
1140                 } else {
1141                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1142                                 proto = PPP_VJC_COMP;
1143                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1144                         } else {
1145                                 proto = PPP_VJC_UNCOMP;
1146                                 cp[0] = skb->data[2];
1147                         }
1148                         kfree_skb(skb);
1149                         skb = new_skb;
1150                         cp = skb_put(skb, len + 2);
1151                         cp[0] = 0;
1152                         cp[1] = proto;
1153                 }
1154                 break;
1155
1156         case PPP_CCP:
1157                 /* peek at outbound CCP frames */
1158                 ppp_ccp_peek(ppp, skb, 0);
1159                 break;
1160         }
1161
1162         /* try to do packet compression */
1163         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0
1164             && proto != PPP_LCP && proto != PPP_CCP) {
1165                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1166                         if (net_ratelimit())
1167                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1168                         goto drop;
1169                 }
1170                 skb = pad_compress_skb(ppp, skb);
1171                 if (!skb)
1172                         goto drop;
1173         }
1174
1175         /*
1176          * If we are waiting for traffic (demand dialling),
1177          * queue it up for pppd to receive.
1178          */
1179         if (ppp->flags & SC_LOOP_TRAFFIC) {
1180                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1181                         goto drop;
1182                 skb_queue_tail(&ppp->file.rq, skb);
1183                 wake_up_interruptible(&ppp->file.rwait);
1184                 return;
1185         }
1186
1187         ppp->xmit_pending = skb;
1188         ppp_push(ppp);
1189         return;
1190
1191  drop:
1192         if (skb)
1193                 kfree_skb(skb);
1194         ++ppp->stats.tx_errors;
1195 }
1196
1197 /*
1198  * Try to send the frame in xmit_pending.
1199  * The caller should have the xmit path locked.
1200  */
1201 static void
1202 ppp_push(struct ppp *ppp)
1203 {
1204         struct list_head *list;
1205         struct channel *pch;
1206         struct sk_buff *skb = ppp->xmit_pending;
1207
1208         if (skb == 0)
1209                 return;
1210
1211         list = &ppp->channels;
1212         if (list_empty(list)) {
1213                 /* nowhere to send the packet, just drop it */
1214                 ppp->xmit_pending = NULL;
1215                 kfree_skb(skb);
1216                 return;
1217         }
1218
1219         if ((ppp->flags & SC_MULTILINK) == 0) {
1220                 /* not doing multilink: send it down the first channel */
1221                 list = list->next;
1222                 pch = list_entry(list, struct channel, clist);
1223
1224                 spin_lock_bh(&pch->downl);
1225                 if (pch->chan) {
1226                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1227                                 ppp->xmit_pending = NULL;
1228                 } else {
1229                         /* channel got unregistered */
1230                         kfree_skb(skb);
1231                         ppp->xmit_pending = NULL;
1232                 }
1233                 spin_unlock_bh(&pch->downl);
1234                 return;
1235         }
1236
1237 #ifdef CONFIG_PPP_MULTILINK
1238         /* Multilink: fragment the packet over as many links
1239            as can take the packet at the moment. */
1240         if (!ppp_mp_explode(ppp, skb))
1241                 return;
1242 #endif /* CONFIG_PPP_MULTILINK */
1243
1244         ppp->xmit_pending = NULL;
1245         kfree_skb(skb);
1246 }
1247
1248 #ifdef CONFIG_PPP_MULTILINK
1249 /*
1250  * Divide a packet to be transmitted into fragments and
1251  * send them out the individual links.
1252  */
1253 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1254 {
1255         int len, fragsize;
1256         int i, bits, hdrlen, mtu;
1257         int flen;
1258         int navail, nfree;
1259         int nbigger;
1260         unsigned char *p, *q;
1261         struct list_head *list;
1262         struct channel *pch;
1263         struct sk_buff *frag;
1264         struct ppp_channel *chan;
1265
1266         nfree = 0;      /* # channels which have no packet already queued */
1267         navail = 0;     /* total # of usable channels (not deregistered) */
1268         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1269         i = 0;
1270         list_for_each_entry(pch, &ppp->channels, clist) {
1271                 navail += pch->avail = (pch->chan != NULL);
1272                 if (pch->avail) {
1273                         if (skb_queue_empty(&pch->file.xq) ||
1274                             !pch->had_frag) {
1275                                 pch->avail = 2;
1276                                 ++nfree;
1277                         }
1278                         if (!pch->had_frag && i < ppp->nxchan)
1279                                 ppp->nxchan = i;
1280                 }
1281                 ++i;
1282         }
1283
1284         /*
1285          * Don't start sending this packet unless at least half of
1286          * the channels are free.  This gives much better TCP
1287          * performance if we have a lot of channels.
1288          */
1289         if (nfree == 0 || nfree < navail / 2)
1290                 return 0;       /* can't take now, leave it in xmit_pending */
1291
1292         /* Do protocol field compression (XXX this should be optional) */
1293         p = skb->data;
1294         len = skb->len;
1295         if (*p == 0) {
1296                 ++p;
1297                 --len;
1298         }
1299
1300         /*
1301          * Decide on fragment size.
1302          * We create a fragment for each free channel regardless of
1303          * how small they are (i.e. even 0 length) in order to minimize
1304          * the time that it will take to detect when a channel drops
1305          * a fragment.
1306          */
1307         fragsize = len;
1308         if (nfree > 1)
1309                 fragsize = ROUNDUP(fragsize, nfree);
1310         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1311            except if nbigger==0, then they all get fragsize. */
1312         nbigger = len % nfree;
1313
1314         /* skip to the channel after the one we last used
1315            and start at that one */
1316         list = &ppp->channels;
1317         for (i = 0; i < ppp->nxchan; ++i) {
1318                 list = list->next;
1319                 if (list == &ppp->channels) {
1320                         i = 0;
1321                         break;
1322                 }
1323         }
1324
1325         /* create a fragment for each channel */
1326         bits = B;
1327         while (nfree > 0 || len > 0) {
1328                 list = list->next;
1329                 if (list == &ppp->channels) {
1330                         i = 0;
1331                         continue;
1332                 }
1333                 pch = list_entry(list, struct channel, clist);
1334                 ++i;
1335                 if (!pch->avail)
1336                         continue;
1337
1338                 /*
1339                  * Skip this channel if it has a fragment pending already and
1340                  * we haven't given a fragment to all of the free channels.
1341                  */
1342                 if (pch->avail == 1) {
1343                         if (nfree > 0)
1344                                 continue;
1345                 } else {
1346                         --nfree;
1347                         pch->avail = 1;
1348                 }
1349
1350                 /* check the channel's mtu and whether it is still attached. */
1351                 spin_lock_bh(&pch->downl);
1352                 if (pch->chan == NULL) {
1353                         /* can't use this channel, it's being deregistered */
1354                         spin_unlock_bh(&pch->downl);
1355                         pch->avail = 0;
1356                         if (--navail == 0)
1357                                 break;
1358                         continue;
1359                 }
1360
1361                 /*
1362                  * Create a fragment for this channel of
1363                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1364                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1365                  * MTU, so we use mtu = 2 + hdrlen.
1366                  */
1367                 if (fragsize > len)
1368                         fragsize = len;
1369                 flen = fragsize;
1370                 mtu = pch->chan->mtu + 2 - hdrlen;
1371                 if (mtu < 4)
1372                         mtu = 4;
1373                 if (flen > mtu)
1374                         flen = mtu;
1375                 if (flen == len && nfree == 0)
1376                         bits |= E;
1377                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1378                 if (frag == 0)
1379                         goto noskb;
1380                 q = skb_put(frag, flen + hdrlen);
1381
1382                 /* make the MP header */
1383                 q[0] = PPP_MP >> 8;
1384                 q[1] = PPP_MP;
1385                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1386                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1387                         q[3] = ppp->nxseq;
1388                 } else {
1389                         q[2] = bits;
1390                         q[3] = ppp->nxseq >> 16;
1391                         q[4] = ppp->nxseq >> 8;
1392                         q[5] = ppp->nxseq;
1393                 }
1394
1395                 /*
1396                  * Copy the data in.
1397                  * Unfortunately there is a bug in older versions of
1398                  * the Linux PPP multilink reconstruction code where it
1399                  * drops 0-length fragments.  Therefore we make sure the
1400                  * fragment has at least one byte of data.  Any bytes
1401                  * we add in this situation will end up as padding on the
1402                  * end of the reconstructed packet.
1403                  */
1404                 if (flen == 0)
1405                         *skb_put(frag, 1) = 0;
1406                 else
1407                         memcpy(q + hdrlen, p, flen);
1408
1409                 /* try to send it down the channel */
1410                 chan = pch->chan;
1411                 if (!skb_queue_empty(&pch->file.xq) ||
1412                     !chan->ops->start_xmit(chan, frag))
1413                         skb_queue_tail(&pch->file.xq, frag);
1414                 pch->had_frag = 1;
1415                 p += flen;
1416                 len -= flen;
1417                 ++ppp->nxseq;
1418                 bits = 0;
1419                 spin_unlock_bh(&pch->downl);
1420
1421                 if (--nbigger == 0 && fragsize > 0)
1422                         --fragsize;
1423         }
1424         ppp->nxchan = i;
1425
1426         return 1;
1427
1428  noskb:
1429         spin_unlock_bh(&pch->downl);
1430         if (ppp->debug & 1)
1431                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1432         ++ppp->stats.tx_errors;
1433         ++ppp->nxseq;
1434         return 1;       /* abandon the frame */
1435 }
1436 #endif /* CONFIG_PPP_MULTILINK */
1437
1438 /*
1439  * Try to send data out on a channel.
1440  */
1441 static void
1442 ppp_channel_push(struct channel *pch)
1443 {
1444         struct sk_buff *skb;
1445         struct ppp *ppp;
1446
1447         spin_lock_bh(&pch->downl);
1448         if (pch->chan != 0) {
1449                 while (!skb_queue_empty(&pch->file.xq)) {
1450                         skb = skb_dequeue(&pch->file.xq);
1451                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1452                                 /* put the packet back and try again later */
1453                                 skb_queue_head(&pch->file.xq, skb);
1454                                 break;
1455                         }
1456                 }
1457         } else {
1458                 /* channel got deregistered */
1459                 skb_queue_purge(&pch->file.xq);
1460         }
1461         spin_unlock_bh(&pch->downl);
1462         /* see if there is anything from the attached unit to be sent */
1463         if (skb_queue_empty(&pch->file.xq)) {
1464                 read_lock_bh(&pch->upl);
1465                 ppp = pch->ppp;
1466                 if (ppp != 0)
1467                         ppp_xmit_process(ppp);
1468                 read_unlock_bh(&pch->upl);
1469         }
1470 }
1471
1472 /*
1473  * Receive-side routines.
1474  */
1475
1476 /* misuse a few fields of the skb for MP reconstruction */
1477 #define sequence        priority
1478 #define BEbits          cb[0]
1479
1480 static inline void
1481 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1482 {
1483         ppp_recv_lock(ppp);
1484         /* ppp->dev == 0 means interface is closing down */
1485         if (ppp->dev != 0)
1486                 ppp_receive_frame(ppp, skb, pch);
1487         else
1488                 kfree_skb(skb);
1489         ppp_recv_unlock(ppp);
1490 }
1491
1492 void
1493 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1494 {
1495         struct channel *pch = chan->ppp;
1496         int proto;
1497
1498         if (pch == 0 || skb->len == 0) {
1499                 kfree_skb(skb);
1500                 return;
1501         }
1502
1503         proto = PPP_PROTO(skb);
1504         read_lock_bh(&pch->upl);
1505         if (pch->ppp == 0 || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1506                 /* put it on the channel queue */
1507                 skb_queue_tail(&pch->file.rq, skb);
1508                 /* drop old frames if queue too long */
1509                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1510                        && (skb = skb_dequeue(&pch->file.rq)) != 0)
1511                         kfree_skb(skb);
1512                 wake_up_interruptible(&pch->file.rwait);
1513         } else {
1514                 ppp_do_recv(pch->ppp, skb, pch);
1515         }
1516         read_unlock_bh(&pch->upl);
1517 }
1518
1519 /* Put a 0-length skb in the receive queue as an error indication */
1520 void
1521 ppp_input_error(struct ppp_channel *chan, int code)
1522 {
1523         struct channel *pch = chan->ppp;
1524         struct sk_buff *skb;
1525
1526         if (pch == 0)
1527                 return;
1528
1529         read_lock_bh(&pch->upl);
1530         if (pch->ppp != 0) {
1531                 skb = alloc_skb(0, GFP_ATOMIC);
1532                 if (skb != 0) {
1533                         skb->len = 0;           /* probably unnecessary */
1534                         skb->cb[0] = code;
1535                         ppp_do_recv(pch->ppp, skb, pch);
1536                 }
1537         }
1538         read_unlock_bh(&pch->upl);
1539 }
1540
1541 /*
1542  * We come in here to process a received frame.
1543  * The receive side of the ppp unit is locked.
1544  */
1545 static void
1546 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1547 {
1548         if (skb->len >= 2) {
1549 #ifdef CONFIG_PPP_MULTILINK
1550                 /* XXX do channel-level decompression here */
1551                 if (PPP_PROTO(skb) == PPP_MP)
1552                         ppp_receive_mp_frame(ppp, skb, pch);
1553                 else
1554 #endif /* CONFIG_PPP_MULTILINK */
1555                         ppp_receive_nonmp_frame(ppp, skb);
1556                 return;
1557         }
1558
1559         if (skb->len > 0)
1560                 /* note: a 0-length skb is used as an error indication */
1561                 ++ppp->stats.rx_length_errors;
1562
1563         kfree_skb(skb);
1564         ppp_receive_error(ppp);
1565 }
1566
1567 static void
1568 ppp_receive_error(struct ppp *ppp)
1569 {
1570         ++ppp->stats.rx_errors;
1571         if (ppp->vj != 0)
1572                 slhc_toss(ppp->vj);
1573 }
1574
1575 static void
1576 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1577 {
1578         struct sk_buff *ns;
1579         int proto, len, npi;
1580
1581         /*
1582          * Decompress the frame, if compressed.
1583          * Note that some decompressors need to see uncompressed frames
1584          * that come in as well as compressed frames.
1585          */
1586         if (ppp->rc_state != 0 && (ppp->rstate & SC_DECOMP_RUN)
1587             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1588                 skb = ppp_decompress_frame(ppp, skb);
1589
1590         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1591                 goto err;
1592
1593         proto = PPP_PROTO(skb);
1594         switch (proto) {
1595         case PPP_VJC_COMP:
1596                 /* decompress VJ compressed packets */
1597                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1598                         goto err;
1599
1600                 if (skb_tailroom(skb) < 124) {
1601                         /* copy to a new sk_buff with more tailroom */
1602                         ns = dev_alloc_skb(skb->len + 128);
1603                         if (ns == 0) {
1604                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1605                                 goto err;
1606                         }
1607                         skb_reserve(ns, 2);
1608                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1609                         kfree_skb(skb);
1610                         skb = ns;
1611                 }
1612                 else if (!pskb_may_pull(skb, skb->len))
1613                         goto err;
1614                 else
1615                         skb->ip_summed = CHECKSUM_NONE;
1616
1617                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1618                 if (len <= 0) {
1619                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1620                         goto err;
1621                 }
1622                 len += 2;
1623                 if (len > skb->len)
1624                         skb_put(skb, len - skb->len);
1625                 else if (len < skb->len)
1626                         skb_trim(skb, len);
1627                 proto = PPP_IP;
1628                 break;
1629
1630         case PPP_VJC_UNCOMP:
1631                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1632                         goto err;
1633
1634                 /* Until we fix the decompressor need to make sure
1635                  * data portion is linear.
1636                  */
1637                 if (!pskb_may_pull(skb, skb->len))
1638                         goto err;
1639
1640                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1641                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1642                         goto err;
1643                 }
1644                 proto = PPP_IP;
1645                 break;
1646
1647         case PPP_CCP:
1648                 ppp_ccp_peek(ppp, skb, 1);
1649                 break;
1650         }
1651
1652         ++ppp->stats.rx_packets;
1653         ppp->stats.rx_bytes += skb->len - 2;
1654
1655         npi = proto_to_npindex(proto);
1656         if (npi < 0) {
1657                 /* control or unknown frame - pass it to pppd */
1658                 skb_queue_tail(&ppp->file.rq, skb);
1659                 /* limit queue length by dropping old frames */
1660                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1661                        && (skb = skb_dequeue(&ppp->file.rq)) != 0)
1662                         kfree_skb(skb);
1663                 /* wake up any process polling or blocking on read */
1664                 wake_up_interruptible(&ppp->file.rwait);
1665
1666         } else {
1667                 /* network protocol frame - give it to the kernel */
1668
1669 #ifdef CONFIG_PPP_FILTER
1670                 /* check if the packet passes the pass and active filters */
1671                 /* the filter instructions are constructed assuming
1672                    a four-byte PPP header on each packet */
1673                 *skb_push(skb, 2) = 0;
1674                 if (ppp->pass_filter
1675                     && sk_run_filter(skb, ppp->pass_filter,
1676                                      ppp->pass_len) == 0) {
1677                         if (ppp->debug & 1)
1678                                 printk(KERN_DEBUG "PPP: inbound frame not passed\n");
1679                         kfree_skb(skb);
1680                         return;
1681                 }
1682                 if (!(ppp->active_filter
1683                       && sk_run_filter(skb, ppp->active_filter,
1684                                        ppp->active_len) == 0))
1685                         ppp->last_recv = jiffies;
1686                 skb_pull(skb, 2);
1687 #else
1688                 ppp->last_recv = jiffies;
1689 #endif /* CONFIG_PPP_FILTER */
1690
1691                 if ((ppp->dev->flags & IFF_UP) == 0
1692                     || ppp->npmode[npi] != NPMODE_PASS) {
1693                         kfree_skb(skb);
1694                 } else {
1695                         /* chop off protocol */
1696                         skb_pull_rcsum(skb, 2);
1697                         skb->dev = ppp->dev;
1698                         skb->protocol = htons(npindex_to_ethertype[npi]);
1699                         skb->mac.raw = skb->data;
1700                         netif_rx(skb);
1701                         ppp->dev->last_rx = jiffies;
1702                 }
1703         }
1704         return;
1705
1706  err:
1707         kfree_skb(skb);
1708         ppp_receive_error(ppp);
1709 }
1710
1711 static struct sk_buff *
1712 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1713 {
1714         int proto = PPP_PROTO(skb);
1715         struct sk_buff *ns;
1716         int len;
1717
1718         /* Until we fix all the decompressor's need to make sure
1719          * data portion is linear.
1720          */
1721         if (!pskb_may_pull(skb, skb->len))
1722                 goto err;
1723
1724         if (proto == PPP_COMP) {
1725                 ns = dev_alloc_skb(ppp->mru + PPP_HDRLEN);
1726                 if (ns == 0) {
1727                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1728                         goto err;
1729                 }
1730                 /* the decompressor still expects the A/C bytes in the hdr */
1731                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1732                                 skb->len + 2, ns->data, ppp->mru + PPP_HDRLEN);
1733                 if (len < 0) {
1734                         /* Pass the compressed frame to pppd as an
1735                            error indication. */
1736                         if (len == DECOMP_FATALERROR)
1737                                 ppp->rstate |= SC_DC_FERROR;
1738                         kfree_skb(ns);
1739                         goto err;
1740                 }
1741
1742                 kfree_skb(skb);
1743                 skb = ns;
1744                 skb_put(skb, len);
1745                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1746
1747         } else {
1748                 /* Uncompressed frame - pass to decompressor so it
1749                    can update its dictionary if necessary. */
1750                 if (ppp->rcomp->incomp)
1751                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1752                                            skb->len + 2);
1753         }
1754
1755         return skb;
1756
1757  err:
1758         ppp->rstate |= SC_DC_ERROR;
1759         ppp_receive_error(ppp);
1760         return skb;
1761 }
1762
1763 #ifdef CONFIG_PPP_MULTILINK
1764 /*
1765  * Receive a multilink frame.
1766  * We put it on the reconstruction queue and then pull off
1767  * as many completed frames as we can.
1768  */
1769 static void
1770 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1771 {
1772         u32 mask, seq;
1773         struct channel *ch;
1774         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1775
1776         if (!pskb_may_pull(skb, mphdrlen) || ppp->mrru == 0)
1777                 goto err;               /* no good, throw it away */
1778
1779         /* Decode sequence number and begin/end bits */
1780         if (ppp->flags & SC_MP_SHORTSEQ) {
1781                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1782                 mask = 0xfff;
1783         } else {
1784                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1785                 mask = 0xffffff;
1786         }
1787         skb->BEbits = skb->data[2];
1788         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1789
1790         /*
1791          * Do protocol ID decompression on the first fragment of each packet.
1792          */
1793         if ((skb->BEbits & B) && (skb->data[0] & 1))
1794                 *skb_push(skb, 1) = 0;
1795
1796         /*
1797          * Expand sequence number to 32 bits, making it as close
1798          * as possible to ppp->minseq.
1799          */
1800         seq |= ppp->minseq & ~mask;
1801         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1802                 seq += mask + 1;
1803         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1804                 seq -= mask + 1;        /* should never happen */
1805         skb->sequence = seq;
1806         pch->lastseq = seq;
1807
1808         /*
1809          * If this packet comes before the next one we were expecting,
1810          * drop it.
1811          */
1812         if (seq_before(seq, ppp->nextseq)) {
1813                 kfree_skb(skb);
1814                 ++ppp->stats.rx_dropped;
1815                 ppp_receive_error(ppp);
1816                 return;
1817         }
1818
1819         /*
1820          * Reevaluate minseq, the minimum over all channels of the
1821          * last sequence number received on each channel.  Because of
1822          * the increasing sequence number rule, we know that any fragment
1823          * before `minseq' which hasn't arrived is never going to arrive.
1824          * The list of channels can't change because we have the receive
1825          * side of the ppp unit locked.
1826          */
1827         list_for_each_entry(ch, &ppp->channels, clist) {
1828                 if (seq_before(ch->lastseq, seq))
1829                         seq = ch->lastseq;
1830         }
1831         if (seq_before(ppp->minseq, seq))
1832                 ppp->minseq = seq;
1833
1834         /* Put the fragment on the reconstruction queue */
1835         ppp_mp_insert(ppp, skb);
1836
1837         /* If the queue is getting long, don't wait any longer for packets
1838            before the start of the queue. */
1839         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN
1840             && seq_before(ppp->minseq, ppp->mrq.next->sequence))
1841                 ppp->minseq = ppp->mrq.next->sequence;
1842
1843         /* Pull completed packets off the queue and receive them. */
1844         while ((skb = ppp_mp_reconstruct(ppp)) != 0)
1845                 ppp_receive_nonmp_frame(ppp, skb);
1846
1847         return;
1848
1849  err:
1850         kfree_skb(skb);
1851         ppp_receive_error(ppp);
1852 }
1853
1854 /*
1855  * Insert a fragment on the MP reconstruction queue.
1856  * The queue is ordered by increasing sequence number.
1857  */
1858 static void
1859 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1860 {
1861         struct sk_buff *p;
1862         struct sk_buff_head *list = &ppp->mrq;
1863         u32 seq = skb->sequence;
1864
1865         /* N.B. we don't need to lock the list lock because we have the
1866            ppp unit receive-side lock. */
1867         for (p = list->next; p != (struct sk_buff *)list; p = p->next)
1868                 if (seq_before(seq, p->sequence))
1869                         break;
1870         __skb_insert(skb, p->prev, p, list);
1871 }
1872
1873 /*
1874  * Reconstruct a packet from the MP fragment queue.
1875  * We go through increasing sequence numbers until we find a
1876  * complete packet, or we get to the sequence number for a fragment
1877  * which hasn't arrived but might still do so.
1878  */
1879 struct sk_buff *
1880 ppp_mp_reconstruct(struct ppp *ppp)
1881 {
1882         u32 seq = ppp->nextseq;
1883         u32 minseq = ppp->minseq;
1884         struct sk_buff_head *list = &ppp->mrq;
1885         struct sk_buff *p, *next;
1886         struct sk_buff *head, *tail;
1887         struct sk_buff *skb = NULL;
1888         int lost = 0, len = 0;
1889
1890         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1891                 return NULL;
1892         head = list->next;
1893         tail = NULL;
1894         for (p = head; p != (struct sk_buff *) list; p = next) {
1895                 next = p->next;
1896                 if (seq_before(p->sequence, seq)) {
1897                         /* this can't happen, anyway ignore the skb */
1898                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1899                                p->sequence, seq);
1900                         head = next;
1901                         continue;
1902                 }
1903                 if (p->sequence != seq) {
1904                         /* Fragment `seq' is missing.  If it is after
1905                            minseq, it might arrive later, so stop here. */
1906                         if (seq_after(seq, minseq))
1907                                 break;
1908                         /* Fragment `seq' is lost, keep going. */
1909                         lost = 1;
1910                         seq = seq_before(minseq, p->sequence)?
1911                                 minseq + 1: p->sequence;
1912                         next = p;
1913                         continue;
1914                 }
1915
1916                 /*
1917                  * At this point we know that all the fragments from
1918                  * ppp->nextseq to seq are either present or lost.
1919                  * Also, there are no complete packets in the queue
1920                  * that have no missing fragments and end before this
1921                  * fragment.
1922                  */
1923
1924                 /* B bit set indicates this fragment starts a packet */
1925                 if (p->BEbits & B) {
1926                         head = p;
1927                         lost = 0;
1928                         len = 0;
1929                 }
1930
1931                 len += p->len;
1932
1933                 /* Got a complete packet yet? */
1934                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1935                         if (len > ppp->mrru + 2) {
1936                                 ++ppp->stats.rx_length_errors;
1937                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1938                                        " is too long (%d)\n", len);
1939                         } else if (p == head) {
1940                                 /* fragment is complete packet - reuse skb */
1941                                 tail = p;
1942                                 skb = skb_get(p);
1943                                 break;
1944                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1945                                 ++ppp->stats.rx_missed_errors;
1946                                 printk(KERN_DEBUG "PPP: no memory for "
1947                                        "reconstructed packet");
1948                         } else {
1949                                 tail = p;
1950                                 break;
1951                         }
1952                         ppp->nextseq = seq + 1;
1953                 }
1954
1955                 /*
1956                  * If this is the ending fragment of a packet,
1957                  * and we haven't found a complete valid packet yet,
1958                  * we can discard up to and including this fragment.
1959                  */
1960                 if (p->BEbits & E)
1961                         head = next;
1962
1963                 ++seq;
1964         }
1965
1966         /* If we have a complete packet, copy it all into one skb. */
1967         if (tail != NULL) {
1968                 /* If we have discarded any fragments,
1969                    signal a receive error. */
1970                 if (head->sequence != ppp->nextseq) {
1971                         if (ppp->debug & 1)
1972                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1973                                        ppp->nextseq, head->sequence-1);
1974                         ++ppp->stats.rx_dropped;
1975                         ppp_receive_error(ppp);
1976                 }
1977
1978                 if (head != tail)
1979                         /* copy to a single skb */
1980                         for (p = head; p != tail->next; p = p->next)
1981                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1982                 ppp->nextseq = tail->sequence + 1;
1983                 head = tail->next;
1984         }
1985
1986         /* Discard all the skbuffs that we have copied the data out of
1987            or that we can't use. */
1988         while ((p = list->next) != head) {
1989                 __skb_unlink(p, list);
1990                 kfree_skb(p);
1991         }
1992
1993         return skb;
1994 }
1995 #endif /* CONFIG_PPP_MULTILINK */
1996
1997 /*
1998  * Channel interface.
1999  */
2000
2001 /*
2002  * Create a new, unattached ppp channel.
2003  */
2004 int
2005 ppp_register_channel(struct ppp_channel *chan)
2006 {
2007         struct channel *pch;
2008
2009         pch = kmalloc(sizeof(struct channel), GFP_KERNEL);
2010         if (pch == 0)
2011                 return -ENOMEM;
2012         memset(pch, 0, sizeof(struct channel));
2013         pch->ppp = NULL;
2014         pch->chan = chan;
2015         chan->ppp = pch;
2016         init_ppp_file(&pch->file, CHANNEL);
2017         pch->file.hdrlen = chan->hdrlen;
2018 #ifdef CONFIG_PPP_MULTILINK
2019         pch->lastseq = -1;
2020 #endif /* CONFIG_PPP_MULTILINK */
2021         init_rwsem(&pch->chan_sem);
2022         spin_lock_init(&pch->downl);
2023         rwlock_init(&pch->upl);
2024         spin_lock_bh(&all_channels_lock);
2025         pch->file.index = ++last_channel_index;
2026         list_add(&pch->list, &new_channels);
2027         atomic_inc(&channel_count);
2028         spin_unlock_bh(&all_channels_lock);
2029         return 0;
2030 }
2031
2032 /*
2033  * Return the index of a channel.
2034  */
2035 int ppp_channel_index(struct ppp_channel *chan)
2036 {
2037         struct channel *pch = chan->ppp;
2038
2039         if (pch != 0)
2040                 return pch->file.index;
2041         return -1;
2042 }
2043
2044 /*
2045  * Return the PPP unit number to which a channel is connected.
2046  */
2047 int ppp_unit_number(struct ppp_channel *chan)
2048 {
2049         struct channel *pch = chan->ppp;
2050         int unit = -1;
2051
2052         if (pch != 0) {
2053                 read_lock_bh(&pch->upl);
2054                 if (pch->ppp != 0)
2055                         unit = pch->ppp->file.index;
2056                 read_unlock_bh(&pch->upl);
2057         }
2058         return unit;
2059 }
2060
2061 /*
2062  * Disconnect a channel from the generic layer.
2063  * This must be called in process context.
2064  */
2065 void
2066 ppp_unregister_channel(struct ppp_channel *chan)
2067 {
2068         struct channel *pch = chan->ppp;
2069
2070         if (pch == 0)
2071                 return;         /* should never happen */
2072         chan->ppp = NULL;
2073
2074         /*
2075          * This ensures that we have returned from any calls into the
2076          * the channel's start_xmit or ioctl routine before we proceed.
2077          */
2078         down_write(&pch->chan_sem);
2079         spin_lock_bh(&pch->downl);
2080         pch->chan = NULL;
2081         spin_unlock_bh(&pch->downl);
2082         up_write(&pch->chan_sem);
2083         ppp_disconnect_channel(pch);
2084         spin_lock_bh(&all_channels_lock);
2085         list_del(&pch->list);
2086         spin_unlock_bh(&all_channels_lock);
2087         pch->file.dead = 1;
2088         wake_up_interruptible(&pch->file.rwait);
2089         if (atomic_dec_and_test(&pch->file.refcnt))
2090                 ppp_destroy_channel(pch);
2091 }
2092
2093 /*
2094  * Callback from a channel when it can accept more to transmit.
2095  * This should be called at BH/softirq level, not interrupt level.
2096  */
2097 void
2098 ppp_output_wakeup(struct ppp_channel *chan)
2099 {
2100         struct channel *pch = chan->ppp;
2101
2102         if (pch == 0)
2103                 return;
2104         ppp_channel_push(pch);
2105 }
2106
2107 /*
2108  * Compression control.
2109  */
2110
2111 /* Process the PPPIOCSCOMPRESS ioctl. */
2112 static int
2113 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2114 {
2115         int err;
2116         struct compressor *cp, *ocomp;
2117         struct ppp_option_data data;
2118         void *state, *ostate;
2119         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2120
2121         err = -EFAULT;
2122         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2123             || (data.length <= CCP_MAX_OPTION_LENGTH
2124                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2125                 goto out;
2126         err = -EINVAL;
2127         if (data.length > CCP_MAX_OPTION_LENGTH
2128             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2129                 goto out;
2130
2131         cp = find_compressor(ccp_option[0]);
2132 #ifdef CONFIG_KMOD
2133         if (cp == 0) {
2134                 request_module("ppp-compress-%d", ccp_option[0]);
2135                 cp = find_compressor(ccp_option[0]);
2136         }
2137 #endif /* CONFIG_KMOD */
2138         if (cp == 0)
2139                 goto out;
2140
2141         err = -ENOBUFS;
2142         if (data.transmit) {
2143                 state = cp->comp_alloc(ccp_option, data.length);
2144                 if (state != 0) {
2145                         ppp_xmit_lock(ppp);
2146                         ppp->xstate &= ~SC_COMP_RUN;
2147                         ocomp = ppp->xcomp;
2148                         ostate = ppp->xc_state;
2149                         ppp->xcomp = cp;
2150                         ppp->xc_state = state;
2151                         ppp_xmit_unlock(ppp);
2152                         if (ostate != 0) {
2153                                 ocomp->comp_free(ostate);
2154                                 module_put(ocomp->owner);
2155                         }
2156                         err = 0;
2157                 } else
2158                         module_put(cp->owner);
2159
2160         } else {
2161                 state = cp->decomp_alloc(ccp_option, data.length);
2162                 if (state != 0) {
2163                         ppp_recv_lock(ppp);
2164                         ppp->rstate &= ~SC_DECOMP_RUN;
2165                         ocomp = ppp->rcomp;
2166                         ostate = ppp->rc_state;
2167                         ppp->rcomp = cp;
2168                         ppp->rc_state = state;
2169                         ppp_recv_unlock(ppp);
2170                         if (ostate != 0) {
2171                                 ocomp->decomp_free(ostate);
2172                                 module_put(ocomp->owner);
2173                         }
2174                         err = 0;
2175                 } else
2176                         module_put(cp->owner);
2177         }
2178
2179  out:
2180         return err;
2181 }
2182
2183 /*
2184  * Look at a CCP packet and update our state accordingly.
2185  * We assume the caller has the xmit or recv path locked.
2186  */
2187 static void
2188 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2189 {
2190         unsigned char *dp;
2191         int len;
2192
2193         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2194                 return; /* no header */
2195         dp = skb->data + 2;
2196
2197         switch (CCP_CODE(dp)) {
2198         case CCP_CONFREQ:
2199
2200                 /* A ConfReq starts negotiation of compression
2201                  * in one direction of transmission,
2202                  * and hence brings it down...but which way?
2203                  *
2204                  * Remember:
2205                  * A ConfReq indicates what the sender would like to receive
2206                  */
2207                 if(inbound)
2208                         /* He is proposing what I should send */
2209                         ppp->xstate &= ~SC_COMP_RUN;
2210                 else
2211                         /* I am proposing to what he should send */
2212                         ppp->rstate &= ~SC_DECOMP_RUN;
2213
2214                 break;
2215
2216         case CCP_TERMREQ:
2217         case CCP_TERMACK:
2218                 /*
2219                  * CCP is going down, both directions of transmission
2220                  */
2221                 ppp->rstate &= ~SC_DECOMP_RUN;
2222                 ppp->xstate &= ~SC_COMP_RUN;
2223                 break;
2224
2225         case CCP_CONFACK:
2226                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2227                         break;
2228                 len = CCP_LENGTH(dp);
2229                 if (!pskb_may_pull(skb, len + 2))
2230                         return;         /* too short */
2231                 dp += CCP_HDRLEN;
2232                 len -= CCP_HDRLEN;
2233                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2234                         break;
2235                 if (inbound) {
2236                         /* we will start receiving compressed packets */
2237                         if (ppp->rc_state == 0)
2238                                 break;
2239                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2240                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2241                                 ppp->rstate |= SC_DECOMP_RUN;
2242                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2243                         }
2244                 } else {
2245                         /* we will soon start sending compressed packets */
2246                         if (ppp->xc_state == 0)
2247                                 break;
2248                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2249                                         ppp->file.index, 0, ppp->debug))
2250                                 ppp->xstate |= SC_COMP_RUN;
2251                 }
2252                 break;
2253
2254         case CCP_RESETACK:
2255                 /* reset the [de]compressor */
2256                 if ((ppp->flags & SC_CCP_UP) == 0)
2257                         break;
2258                 if (inbound) {
2259                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2260                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2261                                 ppp->rstate &= ~SC_DC_ERROR;
2262                         }
2263                 } else {
2264                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2265                                 ppp->xcomp->comp_reset(ppp->xc_state);
2266                 }
2267                 break;
2268         }
2269 }
2270
2271 /* Free up compression resources. */
2272 static void
2273 ppp_ccp_closed(struct ppp *ppp)
2274 {
2275         void *xstate, *rstate;
2276         struct compressor *xcomp, *rcomp;
2277
2278         ppp_lock(ppp);
2279         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2280         ppp->xstate = 0;
2281         xcomp = ppp->xcomp;
2282         xstate = ppp->xc_state;
2283         ppp->xc_state = NULL;
2284         ppp->rstate = 0;
2285         rcomp = ppp->rcomp;
2286         rstate = ppp->rc_state;
2287         ppp->rc_state = NULL;
2288         ppp_unlock(ppp);
2289
2290         if (xstate) {
2291                 xcomp->comp_free(xstate);
2292                 module_put(xcomp->owner);
2293         }
2294         if (rstate) {
2295                 rcomp->decomp_free(rstate);
2296                 module_put(rcomp->owner);
2297         }
2298 }
2299
2300 /* List of compressors. */
2301 static LIST_HEAD(compressor_list);
2302 static DEFINE_SPINLOCK(compressor_list_lock);
2303
2304 struct compressor_entry {
2305         struct list_head list;
2306         struct compressor *comp;
2307 };
2308
2309 static struct compressor_entry *
2310 find_comp_entry(int proto)
2311 {
2312         struct compressor_entry *ce;
2313
2314         list_for_each_entry(ce, &compressor_list, list) {
2315                 if (ce->comp->compress_proto == proto)
2316                         return ce;
2317         }
2318         return NULL;
2319 }
2320
2321 /* Register a compressor */
2322 int
2323 ppp_register_compressor(struct compressor *cp)
2324 {
2325         struct compressor_entry *ce;
2326         int ret;
2327         spin_lock(&compressor_list_lock);
2328         ret = -EEXIST;
2329         if (find_comp_entry(cp->compress_proto) != 0)
2330                 goto out;
2331         ret = -ENOMEM;
2332         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2333         if (ce == 0)
2334                 goto out;
2335         ret = 0;
2336         ce->comp = cp;
2337         list_add(&ce->list, &compressor_list);
2338  out:
2339         spin_unlock(&compressor_list_lock);
2340         return ret;
2341 }
2342
2343 /* Unregister a compressor */
2344 void
2345 ppp_unregister_compressor(struct compressor *cp)
2346 {
2347         struct compressor_entry *ce;
2348
2349         spin_lock(&compressor_list_lock);
2350         ce = find_comp_entry(cp->compress_proto);
2351         if (ce != 0 && ce->comp == cp) {
2352                 list_del(&ce->list);
2353                 kfree(ce);
2354         }
2355         spin_unlock(&compressor_list_lock);
2356 }
2357
2358 /* Find a compressor. */
2359 static struct compressor *
2360 find_compressor(int type)
2361 {
2362         struct compressor_entry *ce;
2363         struct compressor *cp = NULL;
2364
2365         spin_lock(&compressor_list_lock);
2366         ce = find_comp_entry(type);
2367         if (ce != 0) {
2368                 cp = ce->comp;
2369                 if (!try_module_get(cp->owner))
2370                         cp = NULL;
2371         }
2372         spin_unlock(&compressor_list_lock);
2373         return cp;
2374 }
2375
2376 /*
2377  * Miscelleneous stuff.
2378  */
2379
2380 static void
2381 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2382 {
2383         struct slcompress *vj = ppp->vj;
2384
2385         memset(st, 0, sizeof(*st));
2386         st->p.ppp_ipackets = ppp->stats.rx_packets;
2387         st->p.ppp_ierrors = ppp->stats.rx_errors;
2388         st->p.ppp_ibytes = ppp->stats.rx_bytes;
2389         st->p.ppp_opackets = ppp->stats.tx_packets;
2390         st->p.ppp_oerrors = ppp->stats.tx_errors;
2391         st->p.ppp_obytes = ppp->stats.tx_bytes;
2392         if (vj == 0)
2393                 return;
2394         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2395         st->vj.vjs_compressed = vj->sls_o_compressed;
2396         st->vj.vjs_searches = vj->sls_o_searches;
2397         st->vj.vjs_misses = vj->sls_o_misses;
2398         st->vj.vjs_errorin = vj->sls_i_error;
2399         st->vj.vjs_tossed = vj->sls_i_tossed;
2400         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2401         st->vj.vjs_compressedin = vj->sls_i_compressed;
2402 }
2403
2404 /*
2405  * Stuff for handling the lists of ppp units and channels
2406  * and for initialization.
2407  */
2408
2409 /*
2410  * Create a new ppp interface unit.  Fails if it can't allocate memory
2411  * or if there is already a unit with the requested number.
2412  * unit == -1 means allocate a new number.
2413  */
2414 static struct ppp *
2415 ppp_create_interface(int unit, int *retp)
2416 {
2417         struct ppp *ppp;
2418         struct net_device *dev = NULL;
2419         int ret = -ENOMEM;
2420         int i;
2421
2422         ppp = kmalloc(sizeof(struct ppp), GFP_KERNEL);
2423         if (!ppp)
2424                 goto out;
2425         dev = alloc_netdev(0, "", ppp_setup);
2426         if (!dev)
2427                 goto out1;
2428         memset(ppp, 0, sizeof(struct ppp));
2429
2430         ppp->mru = PPP_MRU;
2431         init_ppp_file(&ppp->file, INTERFACE);
2432         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2433         for (i = 0; i < NUM_NP; ++i)
2434                 ppp->npmode[i] = NPMODE_PASS;
2435         INIT_LIST_HEAD(&ppp->channels);
2436         spin_lock_init(&ppp->rlock);
2437         spin_lock_init(&ppp->wlock);
2438 #ifdef CONFIG_PPP_MULTILINK
2439         ppp->minseq = -1;
2440         skb_queue_head_init(&ppp->mrq);
2441 #endif /* CONFIG_PPP_MULTILINK */
2442         ppp->dev = dev;
2443         dev->priv = ppp;
2444
2445         dev->hard_start_xmit = ppp_start_xmit;
2446         dev->get_stats = ppp_net_stats;
2447         dev->do_ioctl = ppp_net_ioctl;
2448
2449         ret = -EEXIST;
2450         mutex_lock(&all_ppp_mutex);
2451         if (unit < 0)
2452                 unit = cardmap_find_first_free(all_ppp_units);
2453         else if (cardmap_get(all_ppp_units, unit) != NULL)
2454                 goto out2;      /* unit already exists */
2455
2456         /* Initialize the new ppp unit */
2457         ppp->file.index = unit;
2458         sprintf(dev->name, "ppp%d", unit);
2459
2460         ret = register_netdev(dev);
2461         if (ret != 0) {
2462                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2463                        dev->name, ret);
2464                 goto out2;
2465         }
2466
2467         atomic_inc(&ppp_unit_count);
2468         cardmap_set(&all_ppp_units, unit, ppp);
2469         mutex_unlock(&all_ppp_mutex);
2470         *retp = 0;
2471         return ppp;
2472
2473 out2:
2474         mutex_unlock(&all_ppp_mutex);
2475         free_netdev(dev);
2476 out1:
2477         kfree(ppp);
2478 out:
2479         *retp = ret;
2480         return NULL;
2481 }
2482
2483 /*
2484  * Initialize a ppp_file structure.
2485  */
2486 static void
2487 init_ppp_file(struct ppp_file *pf, int kind)
2488 {
2489         pf->kind = kind;
2490         skb_queue_head_init(&pf->xq);
2491         skb_queue_head_init(&pf->rq);
2492         atomic_set(&pf->refcnt, 1);
2493         init_waitqueue_head(&pf->rwait);
2494 }
2495
2496 /*
2497  * Take down a ppp interface unit - called when the owning file
2498  * (the one that created the unit) is closed or detached.
2499  */
2500 static void ppp_shutdown_interface(struct ppp *ppp)
2501 {
2502         struct net_device *dev;
2503
2504         mutex_lock(&all_ppp_mutex);
2505         ppp_lock(ppp);
2506         dev = ppp->dev;
2507         ppp->dev = NULL;
2508         ppp_unlock(ppp);
2509         /* This will call dev_close() for us. */
2510         if (dev) {
2511                 unregister_netdev(dev);
2512                 free_netdev(dev);
2513         }
2514         cardmap_set(&all_ppp_units, ppp->file.index, NULL);
2515         ppp->file.dead = 1;
2516         ppp->owner = NULL;
2517         wake_up_interruptible(&ppp->file.rwait);
2518         mutex_unlock(&all_ppp_mutex);
2519 }
2520
2521 /*
2522  * Free the memory used by a ppp unit.  This is only called once
2523  * there are no channels connected to the unit and no file structs
2524  * that reference the unit.
2525  */
2526 static void ppp_destroy_interface(struct ppp *ppp)
2527 {
2528         atomic_dec(&ppp_unit_count);
2529
2530         if (!ppp->file.dead || ppp->n_channels) {
2531                 /* "can't happen" */
2532                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2533                        "n_channels=%d !\n", ppp, ppp->file.dead,
2534                        ppp->n_channels);
2535                 return;
2536         }
2537
2538         ppp_ccp_closed(ppp);
2539         if (ppp->vj) {
2540                 slhc_free(ppp->vj);
2541                 ppp->vj = NULL;
2542         }
2543         skb_queue_purge(&ppp->file.xq);
2544         skb_queue_purge(&ppp->file.rq);
2545 #ifdef CONFIG_PPP_MULTILINK
2546         skb_queue_purge(&ppp->mrq);
2547 #endif /* CONFIG_PPP_MULTILINK */
2548 #ifdef CONFIG_PPP_FILTER
2549         kfree(ppp->pass_filter);
2550         ppp->pass_filter = NULL;
2551         kfree(ppp->active_filter);
2552         ppp->active_filter = NULL;
2553 #endif /* CONFIG_PPP_FILTER */
2554
2555         kfree(ppp);
2556 }
2557
2558 /*
2559  * Locate an existing ppp unit.
2560  * The caller should have locked the all_ppp_mutex.
2561  */
2562 static struct ppp *
2563 ppp_find_unit(int unit)
2564 {
2565         return cardmap_get(all_ppp_units, unit);
2566 }
2567
2568 /*
2569  * Locate an existing ppp channel.
2570  * The caller should have locked the all_channels_lock.
2571  * First we look in the new_channels list, then in the
2572  * all_channels list.  If found in the new_channels list,
2573  * we move it to the all_channels list.  This is for speed
2574  * when we have a lot of channels in use.
2575  */
2576 static struct channel *
2577 ppp_find_channel(int unit)
2578 {
2579         struct channel *pch;
2580
2581         list_for_each_entry(pch, &new_channels, list) {
2582                 if (pch->file.index == unit) {
2583                         list_del(&pch->list);
2584                         list_add(&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         if (unregister_chrdev(PPP_MAJOR, "ppp") != 0)
2686                 printk(KERN_ERR "PPP: failed to unregister PPP device\n");
2687         devfs_remove("ppp");
2688         class_device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2689         class_destroy(ppp_class);
2690 }
2691
2692 /*
2693  * Cardmap implementation.
2694  */
2695 static void *cardmap_get(struct cardmap *map, unsigned int nr)
2696 {
2697         struct cardmap *p;
2698         int i;
2699
2700         for (p = map; p != NULL; ) {
2701                 if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
2702                         return NULL;
2703                 if (p->shift == 0)
2704                         return p->ptr[i];
2705                 nr &= ~(CARDMAP_MASK << p->shift);
2706                 p = p->ptr[i];
2707         }
2708         return NULL;
2709 }
2710
2711 static void cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
2712 {
2713         struct cardmap *p;
2714         int i;
2715
2716         p = *pmap;
2717         if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
2718                 do {
2719                         /* need a new top level */
2720                         struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
2721                         memset(np, 0, sizeof(*np));
2722                         np->ptr[0] = p;
2723                         if (p != NULL) {
2724                                 np->shift = p->shift + CARDMAP_ORDER;
2725                                 p->parent = np;
2726                         } else
2727                                 np->shift = 0;
2728                         p = np;
2729                 } while ((nr >> p->shift) >= CARDMAP_WIDTH);
2730                 *pmap = p;
2731         }
2732         while (p->shift > 0) {
2733                 i = (nr >> p->shift) & CARDMAP_MASK;
2734                 if (p->ptr[i] == NULL) {
2735                         struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
2736                         memset(np, 0, sizeof(*np));
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 }
2752
2753 static unsigned int cardmap_find_first_free(struct cardmap *map)
2754 {
2755         struct cardmap *p;
2756         unsigned int nr = 0;
2757         int i;
2758
2759         if ((p = map) == NULL)
2760                 return 0;
2761         for (;;) {
2762                 i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
2763                 if (i >= CARDMAP_WIDTH) {
2764                         if (p->parent == NULL)
2765                                 return CARDMAP_WIDTH << p->shift;
2766                         p = p->parent;
2767                         i = (nr >> p->shift) & CARDMAP_MASK;
2768                         set_bit(i, &p->inuse);
2769                         continue;
2770                 }
2771                 nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
2772                 if (p->shift == 0 || p->ptr[i] == NULL)
2773                         return nr;
2774                 p = p->ptr[i];
2775         }
2776 }
2777
2778 static void cardmap_destroy(struct cardmap **pmap)
2779 {
2780         struct cardmap *p, *np;
2781         int i;
2782
2783         for (p = *pmap; p != NULL; p = np) {
2784                 if (p->shift != 0) {
2785                         for (i = 0; i < CARDMAP_WIDTH; ++i)
2786                                 if (p->ptr[i] != NULL)
2787                                         break;
2788                         if (i < CARDMAP_WIDTH) {
2789                                 np = p->ptr[i];
2790                                 p->ptr[i] = NULL;
2791                                 continue;
2792                         }
2793                 }
2794                 np = p->parent;
2795                 kfree(p);
2796         }
2797         *pmap = NULL;
2798 }
2799
2800 /* Module/initialization stuff */
2801
2802 module_init(ppp_init);
2803 module_exit(ppp_cleanup);
2804
2805 EXPORT_SYMBOL(ppp_register_channel);
2806 EXPORT_SYMBOL(ppp_unregister_channel);
2807 EXPORT_SYMBOL(ppp_channel_index);
2808 EXPORT_SYMBOL(ppp_unit_number);
2809 EXPORT_SYMBOL(ppp_input);
2810 EXPORT_SYMBOL(ppp_input_error);
2811 EXPORT_SYMBOL(ppp_output_wakeup);
2812 EXPORT_SYMBOL(ppp_register_compressor);
2813 EXPORT_SYMBOL(ppp_unregister_compressor);
2814 MODULE_LICENSE("GPL");
2815 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2816 MODULE_ALIAS("/dev/ppp");