SAFE public projects git trees. - safe/jmp/linux-2.6/blob - drivers/net/ppp_generic.c

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