git.oblomov.eu Git - 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         int             closing;        /* is device closing down? a8 */
 121 #ifdef CONFIG_PPP_MULTILINK
 122         int             nxchan;         /* next channel to send something on */
 123         u32             nxseq;          /* next sequence number to send */
 124         int             mrru;           /* MP: max reconst. receive unit */
 125         u32             nextseq;        /* MP: seq no of next packet */
 126         u32             minseq;         /* MP: min of most recent seqnos */
 127         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
 128 #endif /* CONFIG_PPP_MULTILINK */
 129 #ifdef CONFIG_PPP_FILTER
 130         struct sock_filter *pass_filter;        /* filter for packets to pass */
 131         struct sock_filter *active_filter;/* filter for pkts to reset idle */
 132         unsigned pass_len, active_len;
 133 #endif /* CONFIG_PPP_FILTER */
 134 };
 135
 136 /*
 137  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
 138  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
 139  * SC_MUST_COMP
 140  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
 141  * Bits in xstate: SC_COMP_RUN
 142  */
 143 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
 144                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
 145                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
 146
 147 /*
 148  * Private data structure for each channel.
 149  * This includes the data structure used for multilink.
 150  */
 151 struct channel {
 152         struct ppp_file file;           /* stuff for read/write/poll */
 153         struct list_head list;          /* link in all/new_channels list */
 154         struct ppp_channel *chan;       /* public channel data structure */
 155         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
 156         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
 157         struct ppp      *ppp;           /* ppp unit we're connected to */
 158         struct list_head clist;         /* link in list of channels per unit */
 159         rwlock_t        upl;            /* protects `ppp' */
 160 #ifdef CONFIG_PPP_MULTILINK
 161         u8              avail;          /* flag used in multilink stuff */
 162         u8              had_frag;       /* >= 1 fragments have been sent */
 163         u32             lastseq;        /* MP: last sequence # received */
 164 #endif /* CONFIG_PPP_MULTILINK */
 165 };
 166
 167 /*
 168  * SMP locking issues:
 169  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
 170  * list and the ppp.n_channels field, you need to take both locks
 171  * before you modify them.
 172  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
 173  * channel.downl.
 174  */
 175
 176 /*
 177  * all_ppp_mutex protects the all_ppp_units mapping.
 178  * It also ensures that finding a ppp unit in the all_ppp_units map
 179  * and updating its file.refcnt field is atomic.
 180  */
 181 static DEFINE_MUTEX(all_ppp_mutex);
 182 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 183 static DEFINE_IDR(ppp_units_idr);
 184
 185 /*
 186  * all_channels_lock protects all_channels and last_channel_index,
 187  * and the atomicity of find a channel and updating its file.refcnt
 188  * field.
 189  */
 190 static DEFINE_SPINLOCK(all_channels_lock);
 191 static LIST_HEAD(all_channels);
 192 static LIST_HEAD(new_channels);
 193 static int last_channel_index;
 194 static atomic_t channel_count = ATOMIC_INIT(0);
 195
 196 /* Get the PPP protocol number from a skb */
 197 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
 198
 199 /* We limit the length of ppp->file.rq to this (arbitrary) value */
 200 #define PPP_MAX_RQLEN   32
 201
 202 /*
 203  * Maximum number of multilink fragments queued up.
 204  * This has to be large enough to cope with the maximum latency of
 205  * the slowest channel relative to the others.  Strictly it should
 206  * depend on the number of channels and their characteristics.
 207  */
 208 #define PPP_MP_MAX_QLEN 128
 209
 210 /* Multilink header bits. */
 211 #define B       0x80            /* this fragment begins a packet */
 212 #define E       0x40            /* this fragment ends a packet */
 213
 214 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
 215 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
 216 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
 217
 218 /* Prototypes. */
 219 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 220                                 unsigned int cmd, unsigned long arg);
 221 static void ppp_xmit_process(struct ppp *ppp);
 222 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
 223 static void ppp_push(struct ppp *ppp);
 224 static void ppp_channel_push(struct channel *pch);
 225 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
 226                               struct channel *pch);
 227 static void ppp_receive_error(struct ppp *ppp);
 228 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
 229 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
 230                                             struct sk_buff *skb);
 231 #ifdef CONFIG_PPP_MULTILINK
 232 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
 233                                 struct channel *pch);
 234 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
 235 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
 236 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
 237 #endif /* CONFIG_PPP_MULTILINK */
 238 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
 239 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
 240 static void ppp_ccp_closed(struct ppp *ppp);
 241 static struct compressor *find_compressor(int type);
 242 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
 243 static struct ppp *ppp_create_interface(int unit, int *retp);
 244 static void init_ppp_file(struct ppp_file *pf, int kind);
 245 static void ppp_shutdown_interface(struct ppp *ppp);
 246 static void ppp_destroy_interface(struct ppp *ppp);
 247 static struct ppp *ppp_find_unit(int unit);
 248 static struct channel *ppp_find_channel(int unit);
 249 static int ppp_connect_channel(struct channel *pch, int unit);
 250 static int ppp_disconnect_channel(struct channel *pch);
 251 static void ppp_destroy_channel(struct channel *pch);
 252 static int unit_get(struct idr *p, void *ptr);
 253 static void unit_put(struct idr *p, int n);
 254 static void *unit_find(struct idr *p, int n);
 255
 256 static struct class *ppp_class;
 257
 258 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
 259 static inline int proto_to_npindex(int proto)
 260 {
 261         switch (proto) {
 262         case PPP_IP:
 263                 return NP_IP;
 264         case PPP_IPV6:
 265                 return NP_IPV6;
 266         case PPP_IPX:
 267                 return NP_IPX;
 268         case PPP_AT:
 269                 return NP_AT;
 270         case PPP_MPLS_UC:
 271                 return NP_MPLS_UC;
 272         case PPP_MPLS_MC:
 273                 return NP_MPLS_MC;
 274         }
 275         return -EINVAL;
 276 }
 277
 278 /* Translates an NP index into a PPP protocol number */
 279 static const int npindex_to_proto[NUM_NP] = {
 280         PPP_IP,
 281         PPP_IPV6,
 282         PPP_IPX,
 283         PPP_AT,
 284         PPP_MPLS_UC,
 285         PPP_MPLS_MC,
 286 };
 287
 288 /* Translates an ethertype into an NP index */
 289 static inline int ethertype_to_npindex(int ethertype)
 290 {
 291         switch (ethertype) {
 292         case ETH_P_IP:
 293                 return NP_IP;
 294         case ETH_P_IPV6:
 295                 return NP_IPV6;
 296         case ETH_P_IPX:
 297                 return NP_IPX;
 298         case ETH_P_PPPTALK:
 299         case ETH_P_ATALK:
 300                 return NP_AT;
 301         case ETH_P_MPLS_UC:
 302                 return NP_MPLS_UC;
 303         case ETH_P_MPLS_MC:
 304                 return NP_MPLS_MC;
 305         }
 306         return -1;
 307 }
 308
 309 /* Translates an NP index into an ethertype */
 310 static const int npindex_to_ethertype[NUM_NP] = {
 311         ETH_P_IP,
 312         ETH_P_IPV6,
 313         ETH_P_IPX,
 314         ETH_P_PPPTALK,
 315         ETH_P_MPLS_UC,
 316         ETH_P_MPLS_MC,
 317 };
 318
 319 /*
 320  * Locking shorthand.
 321  */
 322 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
 323 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
 324 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
 325 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
 326 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
 327                                      ppp_recv_lock(ppp); } while (0)
 328 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
 329                                      ppp_xmit_unlock(ppp); } while (0)
 330
 331 /*
 332  * /dev/ppp device routines.
 333  * The /dev/ppp device is used by pppd to control the ppp unit.
 334  * It supports the read, write, ioctl and poll functions.
 335  * Open instances of /dev/ppp can be in one of three states:
 336  * unattached, attached to a ppp unit, or attached to a ppp channel.
 337  */
 338 static int ppp_open(struct inode *inode, struct file *file)
 339 {
 340         cycle_kernel_lock();
 341         /*
 342          * This could (should?) be enforced by the permissions on /dev/ppp.
 343          */
 344         if (!capable(CAP_NET_ADMIN))
 345                 return -EPERM;
 346         return 0;
 347 }
 348
 349 static int ppp_release(struct inode *unused, struct file *file)
 350 {
 351         struct ppp_file *pf = file->private_data;
 352         struct ppp *ppp;
 353
 354         if (pf) {
 355                 file->private_data = NULL;
 356                 if (pf->kind == INTERFACE) {
 357                         ppp = PF_TO_PPP(pf);
 358                         if (file == ppp->owner)
 359                                 ppp_shutdown_interface(ppp);
 360                 }
 361                 if (atomic_dec_and_test(&pf->refcnt)) {
 362                         switch (pf->kind) {
 363                         case INTERFACE:
 364                                 ppp_destroy_interface(PF_TO_PPP(pf));
 365                                 break;
 366                         case CHANNEL:
 367                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
 368                                 break;
 369                         }
 370                 }
 371         }
 372         return 0;
 373 }
 374
 375 static ssize_t ppp_read(struct file *file, char __user *buf,
 376                         size_t count, loff_t *ppos)
 377 {
 378         struct ppp_file *pf = file->private_data;
 379         DECLARE_WAITQUEUE(wait, current);
 380         ssize_t ret;
 381         struct sk_buff *skb = NULL;
 382
 383         ret = count;
 384
 385         if (!pf)
 386                 return -ENXIO;
 387         add_wait_queue(&pf->rwait, &wait);
 388         for (;;) {
 389                 set_current_state(TASK_INTERRUPTIBLE);
 390                 skb = skb_dequeue(&pf->rq);
 391                 if (skb)
 392                         break;
 393                 ret = 0;
 394                 if (pf->dead)
 395                         break;
 396                 if (pf->kind == INTERFACE) {
 397                         /*
 398                          * Return 0 (EOF) on an interface that has no
 399                          * channels connected, unless it is looping
 400                          * network traffic (demand mode).
 401                          */
 402                         struct ppp *ppp = PF_TO_PPP(pf);
 403                         if (ppp->n_channels == 0
 404                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 405                                 break;
 406                 }
 407                 ret = -EAGAIN;
 408                 if (file->f_flags & O_NONBLOCK)
 409                         break;
 410                 ret = -ERESTARTSYS;
 411                 if (signal_pending(current))
 412                         break;
 413                 schedule();
 414         }
 415         set_current_state(TASK_RUNNING);
 416         remove_wait_queue(&pf->rwait, &wait);
 417
 418         if (!skb)
 419                 goto out;
 420
 421         ret = -EOVERFLOW;
 422         if (skb->len > count)
 423                 goto outf;
 424         ret = -EFAULT;
 425         if (copy_to_user(buf, skb->data, skb->len))
 426                 goto outf;
 427         ret = skb->len;
 428
 429  outf:
 430         kfree_skb(skb);
 431  out:
 432         return ret;
 433 }
 434
 435 static ssize_t ppp_write(struct file *file, const char __user *buf,
 436                          size_t count, loff_t *ppos)
 437 {
 438         struct ppp_file *pf = file->private_data;
 439         struct sk_buff *skb;
 440         ssize_t ret;
 441
 442         if (!pf)
 443                 return -ENXIO;
 444         ret = -ENOMEM;
 445         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
 446         if (!skb)
 447                 goto out;
 448         skb_reserve(skb, pf->hdrlen);
 449         ret = -EFAULT;
 450         if (copy_from_user(skb_put(skb, count), buf, count)) {
 451                 kfree_skb(skb);
 452                 goto out;
 453         }
 454
 455         skb_queue_tail(&pf->xq, skb);
 456
 457         switch (pf->kind) {
 458         case INTERFACE:
 459                 ppp_xmit_process(PF_TO_PPP(pf));
 460                 break;
 461         case CHANNEL:
 462                 ppp_channel_push(PF_TO_CHANNEL(pf));
 463                 break;
 464         }
 465
 466         ret = count;
 467
 468  out:
 469         return ret;
 470 }
 471
 472 /* No kernel lock - fine */
 473 static unsigned int ppp_poll(struct file *file, poll_table *wait)
 474 {
 475         struct ppp_file *pf = file->private_data;
 476         unsigned int mask;
 477
 478         if (!pf)
 479                 return 0;
 480         poll_wait(file, &pf->rwait, wait);
 481         mask = POLLOUT | POLLWRNORM;
 482         if (skb_peek(&pf->rq))
 483                 mask |= POLLIN | POLLRDNORM;
 484         if (pf->dead)
 485                 mask |= POLLHUP;
 486         else if (pf->kind == INTERFACE) {
 487                 /* see comment in ppp_read */
 488                 struct ppp *ppp = PF_TO_PPP(pf);
 489                 if (ppp->n_channels == 0
 490                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 491                         mask |= POLLIN | POLLRDNORM;
 492         }
 493
 494         return mask;
 495 }
 496
 497 #ifdef CONFIG_PPP_FILTER
 498 static int get_filter(void __user *arg, struct sock_filter **p)
 499 {
 500         struct sock_fprog uprog;
 501         struct sock_filter *code = NULL;
 502         int len, err;
 503
 504         if (copy_from_user(&uprog, arg, sizeof(uprog)))
 505                 return -EFAULT;
 506
 507         if (!uprog.len) {
 508                 *p = NULL;
 509                 return 0;
 510         }
 511
 512         len = uprog.len * sizeof(struct sock_filter);
 513         code = kmalloc(len, GFP_KERNEL);
 514         if (code == NULL)
 515                 return -ENOMEM;
 516
 517         if (copy_from_user(code, uprog.filter, len)) {
 518                 kfree(code);
 519                 return -EFAULT;
 520         }
 521
 522         err = sk_chk_filter(code, uprog.len);
 523         if (err) {
 524                 kfree(code);
 525                 return err;
 526         }
 527
 528         *p = code;
 529         return uprog.len;
 530 }
 531 #endif /* CONFIG_PPP_FILTER */
 532
 533 static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 534 {
 535         struct ppp_file *pf = file->private_data;
 536         struct ppp *ppp;
 537         int err = -EFAULT, val, val2, i;
 538         struct ppp_idle idle;
 539         struct npioctl npi;
 540         int unit, cflags;
 541         struct slcompress *vj;
 542         void __user *argp = (void __user *)arg;
 543         int __user *p = argp;
 544
 545         if (!pf)
 546                 return ppp_unattached_ioctl(pf, file, cmd, arg);
 547
 548         if (cmd == PPPIOCDETACH) {
 549                 /*
 550                  * We have to be careful here... if the file descriptor
 551                  * has been dup'd, we could have another process in the
 552                  * middle of a poll using the same file *, so we had
 553                  * better not free the interface data structures -
 554                  * instead we fail the ioctl.  Even in this case, we
 555                  * shut down the interface if we are the owner of it.
 556                  * Actually, we should get rid of PPPIOCDETACH, userland
 557                  * (i.e. pppd) could achieve the same effect by closing
 558                  * this fd and reopening /dev/ppp.
 559                  */
 560                 err = -EINVAL;
 561                 lock_kernel();
 562                 if (pf->kind == INTERFACE) {
 563                         ppp = PF_TO_PPP(pf);
 564                         if (file == ppp->owner)
 565                                 ppp_shutdown_interface(ppp);
 566                 }
 567                 if (atomic_long_read(&file->f_count) <= 2) {
 568                         ppp_release(NULL, file);
 569                         err = 0;
 570                 } else
 571                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%ld\n",
 572                                atomic_long_read(&file->f_count));
 573                 unlock_kernel();
 574                 return err;
 575         }
 576
 577         if (pf->kind == CHANNEL) {
 578                 struct channel *pch;
 579                 struct ppp_channel *chan;
 580
 581                 lock_kernel();
 582                 pch = PF_TO_CHANNEL(pf);
 583
 584                 switch (cmd) {
 585                 case PPPIOCCONNECT:
 586                         if (get_user(unit, p))
 587                                 break;
 588                         err = ppp_connect_channel(pch, unit);
 589                         break;
 590
 591                 case PPPIOCDISCONN:
 592                         err = ppp_disconnect_channel(pch);
 593                         break;
 594
 595                 default:
 596                         down_read(&pch->chan_sem);
 597                         chan = pch->chan;
 598                         err = -ENOTTY;
 599                         if (chan && chan->ops->ioctl)
 600                                 err = chan->ops->ioctl(chan, cmd, arg);
 601                         up_read(&pch->chan_sem);
 602                 }
 603                 unlock_kernel();
 604                 return err;
 605         }
 606
 607         if (pf->kind != INTERFACE) {
 608                 /* can't happen */
 609                 printk(KERN_ERR "PPP: not interface or channel??\n");
 610                 return -EINVAL;
 611         }
 612
 613         lock_kernel();
 614         ppp = PF_TO_PPP(pf);
 615         switch (cmd) {
 616         case PPPIOCSMRU:
 617                 if (get_user(val, p))
 618                         break;
 619                 ppp->mru = val;
 620                 err = 0;
 621                 break;
 622
 623         case PPPIOCSFLAGS:
 624                 if (get_user(val, p))
 625                         break;
 626                 ppp_lock(ppp);
 627                 cflags = ppp->flags & ~val;
 628                 ppp->flags = val & SC_FLAG_BITS;
 629                 ppp_unlock(ppp);
 630                 if (cflags & SC_CCP_OPEN)
 631                         ppp_ccp_closed(ppp);
 632                 err = 0;
 633                 break;
 634
 635         case PPPIOCGFLAGS:
 636                 val = ppp->flags | ppp->xstate | ppp->rstate;
 637                 if (put_user(val, p))
 638                         break;
 639                 err = 0;
 640                 break;
 641
 642         case PPPIOCSCOMPRESS:
 643                 err = ppp_set_compress(ppp, arg);
 644                 break;
 645
 646         case PPPIOCGUNIT:
 647                 if (put_user(ppp->file.index, p))
 648                         break;
 649                 err = 0;
 650                 break;
 651
 652         case PPPIOCSDEBUG:
 653                 if (get_user(val, p))
 654                         break;
 655                 ppp->debug = val;
 656                 err = 0;
 657                 break;
 658
 659         case PPPIOCGDEBUG:
 660                 if (put_user(ppp->debug, p))
 661                         break;
 662                 err = 0;
 663                 break;
 664
 665         case PPPIOCGIDLE:
 666                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 667                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
 668                 if (copy_to_user(argp, &idle, sizeof(idle)))
 669                         break;
 670                 err = 0;
 671                 break;
 672
 673         case PPPIOCSMAXCID:
 674                 if (get_user(val, p))
 675                         break;
 676                 val2 = 15;
 677                 if ((val >> 16) != 0) {
 678                         val2 = val >> 16;
 679                         val &= 0xffff;
 680                 }
 681                 vj = slhc_init(val2+1, val+1);
 682                 if (!vj) {
 683                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
 684                         err = -ENOMEM;
 685                         break;
 686                 }
 687                 ppp_lock(ppp);
 688                 if (ppp->vj)
 689                         slhc_free(ppp->vj);
 690                 ppp->vj = vj;
 691                 ppp_unlock(ppp);
 692                 err = 0;
 693                 break;
 694
 695         case PPPIOCGNPMODE:
 696         case PPPIOCSNPMODE:
 697                 if (copy_from_user(&npi, argp, sizeof(npi)))
 698                         break;
 699                 err = proto_to_npindex(npi.protocol);
 700                 if (err < 0)
 701                         break;
 702                 i = err;
 703                 if (cmd == PPPIOCGNPMODE) {
 704                         err = -EFAULT;
 705                         npi.mode = ppp->npmode[i];
 706                         if (copy_to_user(argp, &npi, sizeof(npi)))
 707                                 break;
 708                 } else {
 709                         ppp->npmode[i] = npi.mode;
 710                         /* we may be able to transmit more packets now (??) */
 711                         netif_wake_queue(ppp->dev);
 712                 }
 713                 err = 0;
 714                 break;
 715
 716 #ifdef CONFIG_PPP_FILTER
 717         case PPPIOCSPASS:
 718         {
 719                 struct sock_filter *code;
 720                 err = get_filter(argp, &code);
 721                 if (err >= 0) {
 722                         ppp_lock(ppp);
 723                         kfree(ppp->pass_filter);
 724                         ppp->pass_filter = code;
 725                         ppp->pass_len = err;
 726                         ppp_unlock(ppp);
 727                         err = 0;
 728                 }
 729                 break;
 730         }
 731         case PPPIOCSACTIVE:
 732         {
 733                 struct sock_filter *code;
 734                 err = get_filter(argp, &code);
 735                 if (err >= 0) {
 736                         ppp_lock(ppp);
 737                         kfree(ppp->active_filter);
 738                         ppp->active_filter = code;
 739                         ppp->active_len = err;
 740                         ppp_unlock(ppp);
 741                         err = 0;
 742                 }
 743                 break;
 744         }
 745 #endif /* CONFIG_PPP_FILTER */
 746
 747 #ifdef CONFIG_PPP_MULTILINK
 748         case PPPIOCSMRRU:
 749                 if (get_user(val, p))
 750                         break;
 751                 ppp_recv_lock(ppp);
 752                 ppp->mrru = val;
 753                 ppp_recv_unlock(ppp);
 754                 err = 0;
 755                 break;
 756 #endif /* CONFIG_PPP_MULTILINK */
 757
 758         default:
 759                 err = -ENOTTY;
 760         }
 761         unlock_kernel();
 762         return err;
 763 }
 764
 765 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 766                                 unsigned int cmd, unsigned long arg)
 767 {
 768         int unit, err = -EFAULT;
 769         struct ppp *ppp;
 770         struct channel *chan;
 771         int __user *p = (int __user *)arg;
 772
 773         lock_kernel();
 774         switch (cmd) {
 775         case PPPIOCNEWUNIT:
 776                 /* Create a new ppp unit */
 777                 if (get_user(unit, p))
 778                         break;
 779                 ppp = ppp_create_interface(unit, &err);
 780                 if (!ppp)
 781                         break;
 782                 file->private_data = &ppp->file;
 783                 ppp->owner = file;
 784                 err = -EFAULT;
 785                 if (put_user(ppp->file.index, p))
 786                         break;
 787                 err = 0;
 788                 break;
 789
 790         case PPPIOCATTACH:
 791                 /* Attach to an existing ppp unit */
 792                 if (get_user(unit, p))
 793                         break;
 794                 mutex_lock(&all_ppp_mutex);
 795                 err = -ENXIO;
 796                 ppp = ppp_find_unit(unit);
 797                 if (ppp) {
 798                         atomic_inc(&ppp->file.refcnt);
 799                         file->private_data = &ppp->file;
 800                         err = 0;
 801                 }
 802                 mutex_unlock(&all_ppp_mutex);
 803                 break;
 804
 805         case PPPIOCATTCHAN:
 806                 if (get_user(unit, p))
 807                         break;
 808                 spin_lock_bh(&all_channels_lock);
 809                 err = -ENXIO;
 810                 chan = ppp_find_channel(unit);
 811                 if (chan) {
 812                         atomic_inc(&chan->file.refcnt);
 813                         file->private_data = &chan->file;
 814                         err = 0;
 815                 }
 816                 spin_unlock_bh(&all_channels_lock);
 817                 break;
 818
 819         default:
 820                 err = -ENOTTY;
 821         }
 822         unlock_kernel();
 823         return err;
 824 }
 825
 826 static const struct file_operations ppp_device_fops = {
 827         .owner          = THIS_MODULE,
 828         .read           = ppp_read,
 829         .write          = ppp_write,
 830         .poll           = ppp_poll,
 831         .unlocked_ioctl = ppp_ioctl,
 832         .open           = ppp_open,
 833         .release        = ppp_release
 834 };
 835
 836 #define PPP_MAJOR       108
 837
 838 /* Called at boot time if ppp is compiled into the kernel,
 839    or at module load time (from init_module) if compiled as a module. */
 840 static int __init ppp_init(void)
 841 {
 842         int err;
 843
 844         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
 845         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
 846         if (!err) {
 847                 ppp_class = class_create(THIS_MODULE, "ppp");
 848                 if (IS_ERR(ppp_class)) {
 849                         err = PTR_ERR(ppp_class);
 850                         goto out_chrdev;
 851                 }
 852                 device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL,
 853                               "ppp");
 854         }
 855
 856 out:
 857         if (err)
 858                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
 859         return err;
 860
 861 out_chrdev:
 862         unregister_chrdev(PPP_MAJOR, "ppp");
 863         goto out;
 864 }
 865
 866 /*
 867  * Network interface unit routines.
 868  */
 869 static int
 870 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 871 {
 872         struct ppp *ppp = netdev_priv(dev);
 873         int npi, proto;
 874         unsigned char *pp;
 875
 876         npi = ethertype_to_npindex(ntohs(skb->protocol));
 877         if (npi < 0)
 878                 goto outf;
 879
 880         /* Drop, accept or reject the packet */
 881         switch (ppp->npmode[npi]) {
 882         case NPMODE_PASS:
 883                 break;
 884         case NPMODE_QUEUE:
 885                 /* it would be nice to have a way to tell the network
 886                    system to queue this one up for later. */
 887                 goto outf;
 888         case NPMODE_DROP:
 889         case NPMODE_ERROR:
 890                 goto outf;
 891         }
 892
 893         /* Put the 2-byte PPP protocol number on the front,
 894            making sure there is room for the address and control fields. */
 895         if (skb_cow_head(skb, PPP_HDRLEN))
 896                 goto outf;
 897
 898         pp = skb_push(skb, 2);
 899         proto = npindex_to_proto[npi];
 900         pp[0] = proto >> 8;
 901         pp[1] = proto;
 902
 903         netif_stop_queue(dev);
 904         skb_queue_tail(&ppp->file.xq, skb);
 905         ppp_xmit_process(ppp);
 906         return 0;
 907
 908  outf:
 909         kfree_skb(skb);
 910         ++ppp->dev->stats.tx_dropped;
 911         return 0;
 912 }
 913
 914 static int
 915 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 916 {
 917         struct ppp *ppp = netdev_priv(dev);
 918         int err = -EFAULT;
 919         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
 920         struct ppp_stats stats;
 921         struct ppp_comp_stats cstats;
 922         char *vers;
 923
 924         switch (cmd) {
 925         case SIOCGPPPSTATS:
 926                 ppp_get_stats(ppp, &stats);
 927                 if (copy_to_user(addr, &stats, sizeof(stats)))
 928                         break;
 929                 err = 0;
 930                 break;
 931
 932         case SIOCGPPPCSTATS:
 933                 memset(&cstats, 0, sizeof(cstats));
 934                 if (ppp->xc_state)
 935                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
 936                 if (ppp->rc_state)
 937                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
 938                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
 939                         break;
 940                 err = 0;
 941                 break;
 942
 943         case SIOCGPPPVER:
 944                 vers = PPP_VERSION;
 945                 if (copy_to_user(addr, vers, strlen(vers) + 1))
 946                         break;
 947                 err = 0;
 948                 break;
 949
 950         default:
 951                 err = -EINVAL;
 952         }
 953
 954         return err;
 955 }
 956
 957 static const struct net_device_ops ppp_netdev_ops = {
 958         .ndo_start_xmit = ppp_start_xmit,
 959         .ndo_do_ioctl   = ppp_net_ioctl,
 960 };
 961
 962 static void ppp_setup(struct net_device *dev)
 963 {
 964         dev->netdev_ops = &ppp_netdev_ops;
 965         dev->hard_header_len = PPP_HDRLEN;
 966         dev->mtu = PPP_MTU;
 967         dev->addr_len = 0;
 968         dev->tx_queue_len = 3;
 969         dev->type = ARPHRD_PPP;
 970         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
 971 }
 972
 973 /*
 974  * Transmit-side routines.
 975  */
 976
 977 /*
 978  * Called to do any work queued up on the transmit side
 979  * that can now be done.
 980  */
 981 static void
 982 ppp_xmit_process(struct ppp *ppp)
 983 {
 984         struct sk_buff *skb;
 985
 986         ppp_xmit_lock(ppp);
 987         if (!ppp->closing) {
 988                 ppp_push(ppp);
 989                 while (!ppp->xmit_pending
 990                        && (skb = skb_dequeue(&ppp->file.xq)))
 991                         ppp_send_frame(ppp, skb);
 992                 /* If there's no work left to do, tell the core net
 993                    code that we can accept some more. */
 994                 if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
 995                         netif_wake_queue(ppp->dev);
 996         }
 997         ppp_xmit_unlock(ppp);
 998 }
 999
1000 static inline struct sk_buff *
1001 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1002 {
1003         struct sk_buff *new_skb;
1004         int len;
1005         int new_skb_size = ppp->dev->mtu +
1006                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1007         int compressor_skb_size = ppp->dev->mtu +
1008                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1009         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1010         if (!new_skb) {
1011                 if (net_ratelimit())
1012                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1013                 return NULL;
1014         }
1015         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1016                 skb_reserve(new_skb,
1017                             ppp->dev->hard_header_len - PPP_HDRLEN);
1018
1019         /* compressor still expects A/C bytes in hdr */
1020         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1021                                    new_skb->data, skb->len + 2,
1022                                    compressor_skb_size);
1023         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1024                 kfree_skb(skb);
1025                 skb = new_skb;
1026                 skb_put(skb, len);
1027                 skb_pull(skb, 2);       /* pull off A/C bytes */
1028         } else if (len == 0) {
1029                 /* didn't compress, or CCP not up yet */
1030                 kfree_skb(new_skb);
1031                 new_skb = skb;
1032         } else {
1033                 /*
1034                  * (len < 0)
1035                  * MPPE requires that we do not send unencrypted
1036                  * frames.  The compressor will return -1 if we
1037                  * should drop the frame.  We cannot simply test
1038                  * the compress_proto because MPPE and MPPC share
1039                  * the same number.
1040                  */
1041                 if (net_ratelimit())
1042                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1043                 kfree_skb(skb);
1044                 kfree_skb(new_skb);
1045                 new_skb = NULL;
1046         }
1047         return new_skb;
1048 }
1049
1050 /*
1051  * Compress and send a frame.
1052  * The caller should have locked the xmit path,
1053  * and xmit_pending should be 0.
1054  */
1055 static void
1056 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1057 {
1058         int proto = PPP_PROTO(skb);
1059         struct sk_buff *new_skb;
1060         int len;
1061         unsigned char *cp;
1062
1063         if (proto < 0x8000) {
1064 #ifdef CONFIG_PPP_FILTER
1065                 /* check if we should pass this packet */
1066                 /* the filter instructions are constructed assuming
1067                    a four-byte PPP header on each packet */
1068                 *skb_push(skb, 2) = 1;
1069                 if (ppp->pass_filter
1070                     && sk_run_filter(skb, ppp->pass_filter,
1071                                      ppp->pass_len) == 0) {
1072                         if (ppp->debug & 1)
1073                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1074                         kfree_skb(skb);
1075                         return;
1076                 }
1077                 /* if this packet passes the active filter, record the time */
1078                 if (!(ppp->active_filter
1079                       && sk_run_filter(skb, ppp->active_filter,
1080                                        ppp->active_len) == 0))
1081                         ppp->last_xmit = jiffies;
1082                 skb_pull(skb, 2);
1083 #else
1084                 /* for data packets, record the time */
1085                 ppp->last_xmit = jiffies;
1086 #endif /* CONFIG_PPP_FILTER */
1087         }
1088
1089         ++ppp->dev->stats.tx_packets;
1090         ppp->dev->stats.tx_bytes += skb->len - 2;
1091
1092         switch (proto) {
1093         case PPP_IP:
1094                 if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1095                         break;
1096                 /* try to do VJ TCP header compression */
1097                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1098                                     GFP_ATOMIC);
1099                 if (!new_skb) {
1100                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1101                         goto drop;
1102                 }
1103                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1104                 cp = skb->data + 2;
1105                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1106                                     new_skb->data + 2, &cp,
1107                                     !(ppp->flags & SC_NO_TCP_CCID));
1108                 if (cp == skb->data + 2) {
1109                         /* didn't compress */
1110                         kfree_skb(new_skb);
1111                 } else {
1112                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1113                                 proto = PPP_VJC_COMP;
1114                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1115                         } else {
1116                                 proto = PPP_VJC_UNCOMP;
1117                                 cp[0] = skb->data[2];
1118                         }
1119                         kfree_skb(skb);
1120                         skb = new_skb;
1121                         cp = skb_put(skb, len + 2);
1122                         cp[0] = 0;
1123                         cp[1] = proto;
1124                 }
1125                 break;
1126
1127         case PPP_CCP:
1128                 /* peek at outbound CCP frames */
1129                 ppp_ccp_peek(ppp, skb, 0);
1130                 break;
1131         }
1132
1133         /* try to do packet compression */
1134         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state
1135             && proto != PPP_LCP && proto != PPP_CCP) {
1136                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1137                         if (net_ratelimit())
1138                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1139                         goto drop;
1140                 }
1141                 skb = pad_compress_skb(ppp, skb);
1142                 if (!skb)
1143                         goto drop;
1144         }
1145
1146         /*
1147          * If we are waiting for traffic (demand dialling),
1148          * queue it up for pppd to receive.
1149          */
1150         if (ppp->flags & SC_LOOP_TRAFFIC) {
1151                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1152                         goto drop;
1153                 skb_queue_tail(&ppp->file.rq, skb);
1154                 wake_up_interruptible(&ppp->file.rwait);
1155                 return;
1156         }
1157
1158         ppp->xmit_pending = skb;
1159         ppp_push(ppp);
1160         return;
1161
1162  drop:
1163         if (skb)
1164                 kfree_skb(skb);
1165         ++ppp->dev->stats.tx_errors;
1166 }
1167
1168 /*
1169  * Try to send the frame in xmit_pending.
1170  * The caller should have the xmit path locked.
1171  */
1172 static void
1173 ppp_push(struct ppp *ppp)
1174 {
1175         struct list_head *list;
1176         struct channel *pch;
1177         struct sk_buff *skb = ppp->xmit_pending;
1178
1179         if (!skb)
1180                 return;
1181
1182         list = &ppp->channels;
1183         if (list_empty(list)) {
1184                 /* nowhere to send the packet, just drop it */
1185                 ppp->xmit_pending = NULL;
1186                 kfree_skb(skb);
1187                 return;
1188         }
1189
1190         if ((ppp->flags & SC_MULTILINK) == 0) {
1191                 /* not doing multilink: send it down the first channel */
1192                 list = list->next;
1193                 pch = list_entry(list, struct channel, clist);
1194
1195                 spin_lock_bh(&pch->downl);
1196                 if (pch->chan) {
1197                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1198                                 ppp->xmit_pending = NULL;
1199                 } else {
1200                         /* channel got unregistered */
1201                         kfree_skb(skb);
1202                         ppp->xmit_pending = NULL;
1203                 }
1204                 spin_unlock_bh(&pch->downl);
1205                 return;
1206         }
1207
1208 #ifdef CONFIG_PPP_MULTILINK
1209         /* Multilink: fragment the packet over as many links
1210            as can take the packet at the moment. */
1211         if (!ppp_mp_explode(ppp, skb))
1212                 return;
1213 #endif /* CONFIG_PPP_MULTILINK */
1214
1215         ppp->xmit_pending = NULL;
1216         kfree_skb(skb);
1217 }
1218
1219 #ifdef CONFIG_PPP_MULTILINK
1220 /*
1221  * Divide a packet to be transmitted into fragments and
1222  * send them out the individual links.
1223  */
1224 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1225 {
1226         int len, fragsize;
1227         int i, bits, hdrlen, mtu;
1228         int flen;
1229         int navail, nfree;
1230         int nbigger;
1231         unsigned char *p, *q;
1232         struct list_head *list;
1233         struct channel *pch;
1234         struct sk_buff *frag;
1235         struct ppp_channel *chan;
1236
1237         nfree = 0;      /* # channels which have no packet already queued */
1238         navail = 0;     /* total # of usable channels (not deregistered) */
1239         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1240         i = 0;
1241         list_for_each_entry(pch, &ppp->channels, clist) {
1242                 navail += pch->avail = (pch->chan != NULL);
1243                 if (pch->avail) {
1244                         if (skb_queue_empty(&pch->file.xq) ||
1245                             !pch->had_frag) {
1246                                 pch->avail = 2;
1247                                 ++nfree;
1248                         }
1249                         if (!pch->had_frag && i < ppp->nxchan)
1250                                 ppp->nxchan = i;
1251                 }
1252                 ++i;
1253         }
1254
1255         /*
1256          * Don't start sending this packet unless at least half of
1257          * the channels are free.  This gives much better TCP
1258          * performance if we have a lot of channels.
1259          */
1260         if (nfree == 0 || nfree < navail / 2)
1261                 return 0;       /* can't take now, leave it in xmit_pending */
1262
1263         /* Do protocol field compression (XXX this should be optional) */
1264         p = skb->data;
1265         len = skb->len;
1266         if (*p == 0) {
1267                 ++p;
1268                 --len;
1269         }
1270
1271         /*
1272          * Decide on fragment size.
1273          * We create a fragment for each free channel regardless of
1274          * how small they are (i.e. even 0 length) in order to minimize
1275          * the time that it will take to detect when a channel drops
1276          * a fragment.
1277          */
1278         fragsize = len;
1279         if (nfree > 1)
1280                 fragsize = DIV_ROUND_UP(fragsize, nfree);
1281         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1282            except if nbigger==0, then they all get fragsize. */
1283         nbigger = len % nfree;
1284
1285         /* skip to the channel after the one we last used
1286            and start at that one */
1287         list = &ppp->channels;
1288         for (i = 0; i < ppp->nxchan; ++i) {
1289                 list = list->next;
1290                 if (list == &ppp->channels) {
1291                         i = 0;
1292                         break;
1293                 }
1294         }
1295
1296         /* create a fragment for each channel */
1297         bits = B;
1298         while (nfree > 0 || len > 0) {
1299                 list = list->next;
1300                 if (list == &ppp->channels) {
1301                         i = 0;
1302                         continue;
1303                 }
1304                 pch = list_entry(list, struct channel, clist);
1305                 ++i;
1306                 if (!pch->avail)
1307                         continue;
1308
1309                 /*
1310                  * Skip this channel if it has a fragment pending already and
1311                  * we haven't given a fragment to all of the free channels.
1312                  */
1313                 if (pch->avail == 1) {
1314                         if (nfree > 0)
1315                                 continue;
1316                 } else {
1317                         --nfree;
1318                         pch->avail = 1;
1319                 }
1320
1321                 /* check the channel's mtu and whether it is still attached. */
1322                 spin_lock_bh(&pch->downl);
1323                 if (pch->chan == NULL) {
1324                         /* can't use this channel, it's being deregistered */
1325                         spin_unlock_bh(&pch->downl);
1326                         pch->avail = 0;
1327                         if (--navail == 0)
1328                                 break;
1329                         continue;
1330                 }
1331
1332                 /*
1333                  * Create a fragment for this channel of
1334                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1335                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1336                  * MTU, so we use mtu = 2 + hdrlen.
1337                  */
1338                 if (fragsize > len)
1339                         fragsize = len;
1340                 flen = fragsize;
1341                 mtu = pch->chan->mtu + 2 - hdrlen;
1342                 if (mtu < 4)
1343                         mtu = 4;
1344                 if (flen > mtu)
1345                         flen = mtu;
1346                 if (flen == len && nfree == 0)
1347                         bits |= E;
1348                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1349                 if (!frag)
1350                         goto noskb;
1351                 q = skb_put(frag, flen + hdrlen);
1352
1353                 /* make the MP header */
1354                 q[0] = PPP_MP >> 8;
1355                 q[1] = PPP_MP;
1356                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1357                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1358                         q[3] = ppp->nxseq;
1359                 } else {
1360                         q[2] = bits;
1361                         q[3] = ppp->nxseq >> 16;
1362                         q[4] = ppp->nxseq >> 8;
1363                         q[5] = ppp->nxseq;
1364                 }
1365
1366                 /*
1367                  * Copy the data in.
1368                  * Unfortunately there is a bug in older versions of
1369                  * the Linux PPP multilink reconstruction code where it
1370                  * drops 0-length fragments.  Therefore we make sure the
1371                  * fragment has at least one byte of data.  Any bytes
1372                  * we add in this situation will end up as padding on the
1373                  * end of the reconstructed packet.
1374                  */
1375                 if (flen == 0)
1376                         *skb_put(frag, 1) = 0;
1377                 else
1378                         memcpy(q + hdrlen, p, flen);
1379
1380                 /* try to send it down the channel */
1381                 chan = pch->chan;
1382                 if (!skb_queue_empty(&pch->file.xq) ||
1383                     !chan->ops->start_xmit(chan, frag))
1384                         skb_queue_tail(&pch->file.xq, frag);
1385                 pch->had_frag = 1;
1386                 p += flen;
1387                 len -= flen;
1388                 ++ppp->nxseq;
1389                 bits = 0;
1390                 spin_unlock_bh(&pch->downl);
1391
1392                 if (--nbigger == 0 && fragsize > 0)
1393                         --fragsize;
1394         }
1395         ppp->nxchan = i;
1396
1397         return 1;
1398
1399  noskb:
1400         spin_unlock_bh(&pch->downl);
1401         if (ppp->debug & 1)
1402                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1403         ++ppp->dev->stats.tx_errors;
1404         ++ppp->nxseq;
1405         return 1;       /* abandon the frame */
1406 }
1407 #endif /* CONFIG_PPP_MULTILINK */
1408
1409 /*
1410  * Try to send data out on a channel.
1411  */
1412 static void
1413 ppp_channel_push(struct channel *pch)
1414 {
1415         struct sk_buff *skb;
1416         struct ppp *ppp;
1417
1418         spin_lock_bh(&pch->downl);
1419         if (pch->chan) {
1420                 while (!skb_queue_empty(&pch->file.xq)) {
1421                         skb = skb_dequeue(&pch->file.xq);
1422                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1423                                 /* put the packet back and try again later */
1424                                 skb_queue_head(&pch->file.xq, skb);
1425                                 break;
1426                         }
1427                 }
1428         } else {
1429                 /* channel got deregistered */
1430                 skb_queue_purge(&pch->file.xq);
1431         }
1432         spin_unlock_bh(&pch->downl);
1433         /* see if there is anything from the attached unit to be sent */
1434         if (skb_queue_empty(&pch->file.xq)) {
1435                 read_lock_bh(&pch->upl);
1436                 ppp = pch->ppp;
1437                 if (ppp)
1438                         ppp_xmit_process(ppp);
1439                 read_unlock_bh(&pch->upl);
1440         }
1441 }
1442
1443 /*
1444  * Receive-side routines.
1445  */
1446
1447 /* misuse a few fields of the skb for MP reconstruction */
1448 #define sequence        priority
1449 #define BEbits          cb[0]
1450
1451 static inline void
1452 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1453 {
1454         ppp_recv_lock(ppp);
1455         if (!ppp->closing)
1456                 ppp_receive_frame(ppp, skb, pch);
1457         else
1458                 kfree_skb(skb);
1459         ppp_recv_unlock(ppp);
1460 }
1461
1462 void
1463 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1464 {
1465         struct channel *pch = chan->ppp;
1466         int proto;
1467
1468         if (!pch || skb->len == 0) {
1469                 kfree_skb(skb);
1470                 return;
1471         }
1472
1473         proto = PPP_PROTO(skb);
1474         read_lock_bh(&pch->upl);
1475         if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1476                 /* put it on the channel queue */
1477                 skb_queue_tail(&pch->file.rq, skb);
1478                 /* drop old frames if queue too long */
1479                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1480                        && (skb = skb_dequeue(&pch->file.rq)))
1481                         kfree_skb(skb);
1482                 wake_up_interruptible(&pch->file.rwait);
1483         } else {
1484                 ppp_do_recv(pch->ppp, skb, pch);
1485         }
1486         read_unlock_bh(&pch->upl);
1487 }
1488
1489 /* Put a 0-length skb in the receive queue as an error indication */
1490 void
1491 ppp_input_error(struct ppp_channel *chan, int code)
1492 {
1493         struct channel *pch = chan->ppp;
1494         struct sk_buff *skb;
1495
1496         if (!pch)
1497                 return;
1498
1499         read_lock_bh(&pch->upl);
1500         if (pch->ppp) {
1501                 skb = alloc_skb(0, GFP_ATOMIC);
1502                 if (skb) {
1503                         skb->len = 0;           /* probably unnecessary */
1504                         skb->cb[0] = code;
1505                         ppp_do_recv(pch->ppp, skb, pch);
1506                 }
1507         }
1508         read_unlock_bh(&pch->upl);
1509 }
1510
1511 /*
1512  * We come in here to process a received frame.
1513  * The receive side of the ppp unit is locked.
1514  */
1515 static void
1516 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1517 {
1518         if (pskb_may_pull(skb, 2)) {
1519 #ifdef CONFIG_PPP_MULTILINK
1520                 /* XXX do channel-level decompression here */
1521                 if (PPP_PROTO(skb) == PPP_MP)
1522                         ppp_receive_mp_frame(ppp, skb, pch);
1523                 else
1524 #endif /* CONFIG_PPP_MULTILINK */
1525                         ppp_receive_nonmp_frame(ppp, skb);
1526                 return;
1527         }
1528
1529         if (skb->len > 0)
1530                 /* note: a 0-length skb is used as an error indication */
1531                 ++ppp->dev->stats.rx_length_errors;
1532
1533         kfree_skb(skb);
1534         ppp_receive_error(ppp);
1535 }
1536
1537 static void
1538 ppp_receive_error(struct ppp *ppp)
1539 {
1540         ++ppp->dev->stats.rx_errors;
1541         if (ppp->vj)
1542                 slhc_toss(ppp->vj);
1543 }
1544
1545 static void
1546 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1547 {
1548         struct sk_buff *ns;
1549         int proto, len, npi;
1550
1551         /*
1552          * Decompress the frame, if compressed.
1553          * Note that some decompressors need to see uncompressed frames
1554          * that come in as well as compressed frames.
1555          */
1556         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)
1557             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1558                 skb = ppp_decompress_frame(ppp, skb);
1559
1560         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1561                 goto err;
1562
1563         proto = PPP_PROTO(skb);
1564         switch (proto) {
1565         case PPP_VJC_COMP:
1566                 /* decompress VJ compressed packets */
1567                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1568                         goto err;
1569
1570                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1571                         /* copy to a new sk_buff with more tailroom */
1572                         ns = dev_alloc_skb(skb->len + 128);
1573                         if (!ns) {
1574                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1575                                 goto err;
1576                         }
1577                         skb_reserve(ns, 2);
1578                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1579                         kfree_skb(skb);
1580                         skb = ns;
1581                 }
1582                 else
1583                         skb->ip_summed = CHECKSUM_NONE;
1584
1585                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1586                 if (len <= 0) {
1587                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1588                         goto err;
1589                 }
1590                 len += 2;
1591                 if (len > skb->len)
1592                         skb_put(skb, len - skb->len);
1593                 else if (len < skb->len)
1594                         skb_trim(skb, len);
1595                 proto = PPP_IP;
1596                 break;
1597
1598         case PPP_VJC_UNCOMP:
1599                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1600                         goto err;
1601
1602                 /* Until we fix the decompressor need to make sure
1603                  * data portion is linear.
1604                  */
1605                 if (!pskb_may_pull(skb, skb->len))
1606                         goto err;
1607
1608                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1609                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1610                         goto err;
1611                 }
1612                 proto = PPP_IP;
1613                 break;
1614
1615         case PPP_CCP:
1616                 ppp_ccp_peek(ppp, skb, 1);
1617                 break;
1618         }
1619
1620         ++ppp->dev->stats.rx_packets;
1621         ppp->dev->stats.rx_bytes += skb->len - 2;
1622
1623         npi = proto_to_npindex(proto);
1624         if (npi < 0) {
1625                 /* control or unknown frame - pass it to pppd */
1626                 skb_queue_tail(&ppp->file.rq, skb);
1627                 /* limit queue length by dropping old frames */
1628                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1629                        && (skb = skb_dequeue(&ppp->file.rq)))
1630                         kfree_skb(skb);
1631                 /* wake up any process polling or blocking on read */
1632                 wake_up_interruptible(&ppp->file.rwait);
1633
1634         } else {
1635                 /* network protocol frame - give it to the kernel */
1636
1637 #ifdef CONFIG_PPP_FILTER
1638                 /* check if the packet passes the pass and active filters */
1639                 /* the filter instructions are constructed assuming
1640                    a four-byte PPP header on each packet */
1641                 if (ppp->pass_filter || ppp->active_filter) {
1642                         if (skb_cloned(skb) &&
1643                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
1644                                 goto err;
1645
1646                         *skb_push(skb, 2) = 0;
1647                         if (ppp->pass_filter
1648                             && sk_run_filter(skb, ppp->pass_filter,
1649                                              ppp->pass_len) == 0) {
1650                                 if (ppp->debug & 1)
1651                                         printk(KERN_DEBUG "PPP: inbound frame "
1652                                                "not passed\n");
1653                                 kfree_skb(skb);
1654                                 return;
1655                         }
1656                         if (!(ppp->active_filter
1657                               && sk_run_filter(skb, ppp->active_filter,
1658                                                ppp->active_len) == 0))
1659                                 ppp->last_recv = jiffies;
1660                         __skb_pull(skb, 2);
1661                 } else
1662 #endif /* CONFIG_PPP_FILTER */
1663                         ppp->last_recv = jiffies;
1664
1665                 if ((ppp->dev->flags & IFF_UP) == 0
1666                     || ppp->npmode[npi] != NPMODE_PASS) {
1667                         kfree_skb(skb);
1668                 } else {
1669                         /* chop off protocol */
1670                         skb_pull_rcsum(skb, 2);
1671                         skb->dev = ppp->dev;
1672                         skb->protocol = htons(npindex_to_ethertype[npi]);
1673                         skb_reset_mac_header(skb);
1674                         netif_rx(skb);
1675                 }
1676         }
1677         return;
1678
1679  err:
1680         kfree_skb(skb);
1681         ppp_receive_error(ppp);
1682 }
1683
1684 static struct sk_buff *
1685 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1686 {
1687         int proto = PPP_PROTO(skb);
1688         struct sk_buff *ns;
1689         int len;
1690
1691         /* Until we fix all the decompressor's need to make sure
1692          * data portion is linear.
1693          */
1694         if (!pskb_may_pull(skb, skb->len))
1695                 goto err;
1696
1697         if (proto == PPP_COMP) {
1698                 int obuff_size;
1699
1700                 switch(ppp->rcomp->compress_proto) {
1701                 case CI_MPPE:
1702                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1703                         break;
1704                 default:
1705                         obuff_size = ppp->mru + PPP_HDRLEN;
1706                         break;
1707                 }
1708
1709                 ns = dev_alloc_skb(obuff_size);
1710                 if (!ns) {
1711                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1712                         goto err;
1713                 }
1714                 /* the decompressor still expects the A/C bytes in the hdr */
1715                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1716                                 skb->len + 2, ns->data, obuff_size);
1717                 if (len < 0) {
1718                         /* Pass the compressed frame to pppd as an
1719                            error indication. */
1720                         if (len == DECOMP_FATALERROR)
1721                                 ppp->rstate |= SC_DC_FERROR;
1722                         kfree_skb(ns);
1723                         goto err;
1724                 }
1725
1726                 kfree_skb(skb);
1727                 skb = ns;
1728                 skb_put(skb, len);
1729                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1730
1731         } else {
1732                 /* Uncompressed frame - pass to decompressor so it
1733                    can update its dictionary if necessary. */
1734                 if (ppp->rcomp->incomp)
1735                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1736                                            skb->len + 2);
1737         }
1738
1739         return skb;
1740
1741  err:
1742         ppp->rstate |= SC_DC_ERROR;
1743         ppp_receive_error(ppp);
1744         return skb;
1745 }
1746
1747 #ifdef CONFIG_PPP_MULTILINK
1748 /*
1749  * Receive a multilink frame.
1750  * We put it on the reconstruction queue and then pull off
1751  * as many completed frames as we can.
1752  */
1753 static void
1754 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1755 {
1756         u32 mask, seq;
1757         struct channel *ch;
1758         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1759
1760         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1761                 goto err;               /* no good, throw it away */
1762
1763         /* Decode sequence number and begin/end bits */
1764         if (ppp->flags & SC_MP_SHORTSEQ) {
1765                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1766                 mask = 0xfff;
1767         } else {
1768                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1769                 mask = 0xffffff;
1770         }
1771         skb->BEbits = skb->data[2];
1772         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1773
1774         /*
1775          * Do protocol ID decompression on the first fragment of each packet.
1776          */
1777         if ((skb->BEbits & B) && (skb->data[0] & 1))
1778                 *skb_push(skb, 1) = 0;
1779
1780         /*
1781          * Expand sequence number to 32 bits, making it as close
1782          * as possible to ppp->minseq.
1783          */
1784         seq |= ppp->minseq & ~mask;
1785         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1786                 seq += mask + 1;
1787         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1788                 seq -= mask + 1;        /* should never happen */
1789         skb->sequence = seq;
1790         pch->lastseq = seq;
1791
1792         /*
1793          * If this packet comes before the next one we were expecting,
1794          * drop it.
1795          */
1796         if (seq_before(seq, ppp->nextseq)) {
1797                 kfree_skb(skb);
1798                 ++ppp->dev->stats.rx_dropped;
1799                 ppp_receive_error(ppp);
1800                 return;
1801         }
1802
1803         /*
1804          * Reevaluate minseq, the minimum over all channels of the
1805          * last sequence number received on each channel.  Because of
1806          * the increasing sequence number rule, we know that any fragment
1807          * before `minseq' which hasn't arrived is never going to arrive.
1808          * The list of channels can't change because we have the receive
1809          * side of the ppp unit locked.
1810          */
1811         list_for_each_entry(ch, &ppp->channels, clist) {
1812                 if (seq_before(ch->lastseq, seq))
1813                         seq = ch->lastseq;
1814         }
1815         if (seq_before(ppp->minseq, seq))
1816                 ppp->minseq = seq;
1817
1818         /* Put the fragment on the reconstruction queue */
1819         ppp_mp_insert(ppp, skb);
1820
1821         /* If the queue is getting long, don't wait any longer for packets
1822            before the start of the queue. */
1823         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN) {
1824                 struct sk_buff *skb = skb_peek(&ppp->mrq);
1825                 if (seq_before(ppp->minseq, skb->sequence))
1826                         ppp->minseq = skb->sequence;
1827         }
1828
1829         /* Pull completed packets off the queue and receive them. */
1830         while ((skb = ppp_mp_reconstruct(ppp)))
1831                 ppp_receive_nonmp_frame(ppp, skb);
1832
1833         return;
1834
1835  err:
1836         kfree_skb(skb);
1837         ppp_receive_error(ppp);
1838 }
1839
1840 /*
1841  * Insert a fragment on the MP reconstruction queue.
1842  * The queue is ordered by increasing sequence number.
1843  */
1844 static void
1845 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1846 {
1847         struct sk_buff *p;
1848         struct sk_buff_head *list = &ppp->mrq;
1849         u32 seq = skb->sequence;
1850
1851         /* N.B. we don't need to lock the list lock because we have the
1852            ppp unit receive-side lock. */
1853         skb_queue_walk(list, p) {
1854                 if (seq_before(seq, p->sequence))
1855                         break;
1856         }
1857         __skb_queue_before(list, p, skb);
1858 }
1859
1860 /*
1861  * Reconstruct a packet from the MP fragment queue.
1862  * We go through increasing sequence numbers until we find a
1863  * complete packet, or we get to the sequence number for a fragment
1864  * which hasn't arrived but might still do so.
1865  */
1866 static struct sk_buff *
1867 ppp_mp_reconstruct(struct ppp *ppp)
1868 {
1869         u32 seq = ppp->nextseq;
1870         u32 minseq = ppp->minseq;
1871         struct sk_buff_head *list = &ppp->mrq;
1872         struct sk_buff *p, *next;
1873         struct sk_buff *head, *tail;
1874         struct sk_buff *skb = NULL;
1875         int lost = 0, len = 0;
1876
1877         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1878                 return NULL;
1879         head = list->next;
1880         tail = NULL;
1881         for (p = head; p != (struct sk_buff *) list; p = next) {
1882                 next = p->next;
1883                 if (seq_before(p->sequence, seq)) {
1884                         /* this can't happen, anyway ignore the skb */
1885                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1886                                p->sequence, seq);
1887                         head = next;
1888                         continue;
1889                 }
1890                 if (p->sequence != seq) {
1891                         /* Fragment `seq' is missing.  If it is after
1892                            minseq, it might arrive later, so stop here. */
1893                         if (seq_after(seq, minseq))
1894                                 break;
1895                         /* Fragment `seq' is lost, keep going. */
1896                         lost = 1;
1897                         seq = seq_before(minseq, p->sequence)?
1898                                 minseq + 1: p->sequence;
1899                         next = p;
1900                         continue;
1901                 }
1902
1903                 /*
1904                  * At this point we know that all the fragments from
1905                  * ppp->nextseq to seq are either present or lost.
1906                  * Also, there are no complete packets in the queue
1907                  * that have no missing fragments and end before this
1908                  * fragment.
1909                  */
1910
1911                 /* B bit set indicates this fragment starts a packet */
1912                 if (p->BEbits & B) {
1913                         head = p;
1914                         lost = 0;
1915                         len = 0;
1916                 }
1917
1918                 len += p->len;
1919
1920                 /* Got a complete packet yet? */
1921                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1922                         if (len > ppp->mrru + 2) {
1923                                 ++ppp->dev->stats.rx_length_errors;
1924                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1925                                        " is too long (%d)\n", len);
1926                         } else if (p == head) {
1927                                 /* fragment is complete packet - reuse skb */
1928                                 tail = p;
1929                                 skb = skb_get(p);
1930                                 break;
1931                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1932                                 ++ppp->dev->stats.rx_missed_errors;
1933                                 printk(KERN_DEBUG "PPP: no memory for "
1934                                        "reconstructed packet");
1935                         } else {
1936                                 tail = p;
1937                                 break;
1938                         }
1939                         ppp->nextseq = seq + 1;
1940                 }
1941
1942                 /*
1943                  * If this is the ending fragment of a packet,
1944                  * and we haven't found a complete valid packet yet,
1945                  * we can discard up to and including this fragment.
1946                  */
1947                 if (p->BEbits & E)
1948                         head = next;
1949
1950                 ++seq;
1951         }
1952
1953         /* If we have a complete packet, copy it all into one skb. */
1954         if (tail != NULL) {
1955                 /* If we have discarded any fragments,
1956                    signal a receive error. */
1957                 if (head->sequence != ppp->nextseq) {
1958                         if (ppp->debug & 1)
1959                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1960                                        ppp->nextseq, head->sequence-1);
1961                         ++ppp->dev->stats.rx_dropped;
1962                         ppp_receive_error(ppp);
1963                 }
1964
1965                 if (head != tail)
1966                         /* copy to a single skb */
1967                         for (p = head; p != tail->next; p = p->next)
1968                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1969                 ppp->nextseq = tail->sequence + 1;
1970                 head = tail->next;
1971         }
1972
1973         /* Discard all the skbuffs that we have copied the data out of
1974            or that we can't use. */
1975         while ((p = list->next) != head) {
1976                 __skb_unlink(p, list);
1977                 kfree_skb(p);
1978         }
1979
1980         return skb;
1981 }
1982 #endif /* CONFIG_PPP_MULTILINK */
1983
1984 /*
1985  * Channel interface.
1986  */
1987
1988 /*
1989  * Create a new, unattached ppp channel.
1990  */
1991 int
1992 ppp_register_channel(struct ppp_channel *chan)
1993 {
1994         struct channel *pch;
1995
1996         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
1997         if (!pch)
1998                 return -ENOMEM;
1999         pch->ppp = NULL;
2000         pch->chan = chan;
2001         chan->ppp = pch;
2002         init_ppp_file(&pch->file, CHANNEL);
2003         pch->file.hdrlen = chan->hdrlen;
2004 #ifdef CONFIG_PPP_MULTILINK
2005         pch->lastseq = -1;
2006 #endif /* CONFIG_PPP_MULTILINK */
2007         init_rwsem(&pch->chan_sem);
2008         spin_lock_init(&pch->downl);
2009         rwlock_init(&pch->upl);
2010         spin_lock_bh(&all_channels_lock);
2011         pch->file.index = ++last_channel_index;
2012         list_add(&pch->list, &new_channels);
2013         atomic_inc(&channel_count);
2014         spin_unlock_bh(&all_channels_lock);
2015         return 0;
2016 }
2017
2018 /*
2019  * Return the index of a channel.
2020  */
2021 int ppp_channel_index(struct ppp_channel *chan)
2022 {
2023         struct channel *pch = chan->ppp;
2024
2025         if (pch)
2026                 return pch->file.index;
2027         return -1;
2028 }
2029
2030 /*
2031  * Return the PPP unit number to which a channel is connected.
2032  */
2033 int ppp_unit_number(struct ppp_channel *chan)
2034 {
2035         struct channel *pch = chan->ppp;
2036         int unit = -1;
2037
2038         if (pch) {
2039                 read_lock_bh(&pch->upl);
2040                 if (pch->ppp)
2041                         unit = pch->ppp->file.index;
2042                 read_unlock_bh(&pch->upl);
2043         }
2044         return unit;
2045 }
2046
2047 /*
2048  * Disconnect a channel from the generic layer.
2049  * This must be called in process context.
2050  */
2051 void
2052 ppp_unregister_channel(struct ppp_channel *chan)
2053 {
2054         struct channel *pch = chan->ppp;
2055
2056         if (!pch)
2057                 return;         /* should never happen */
2058         chan->ppp = NULL;
2059
2060         /*
2061          * This ensures that we have returned from any calls into the
2062          * the channel's start_xmit or ioctl routine before we proceed.
2063          */
2064         down_write(&pch->chan_sem);
2065         spin_lock_bh(&pch->downl);
2066         pch->chan = NULL;
2067         spin_unlock_bh(&pch->downl);
2068         up_write(&pch->chan_sem);
2069         ppp_disconnect_channel(pch);
2070         spin_lock_bh(&all_channels_lock);
2071         list_del(&pch->list);
2072         spin_unlock_bh(&all_channels_lock);
2073         pch->file.dead = 1;
2074         wake_up_interruptible(&pch->file.rwait);
2075         if (atomic_dec_and_test(&pch->file.refcnt))
2076                 ppp_destroy_channel(pch);
2077 }
2078
2079 /*
2080  * Callback from a channel when it can accept more to transmit.
2081  * This should be called at BH/softirq level, not interrupt level.
2082  */
2083 void
2084 ppp_output_wakeup(struct ppp_channel *chan)
2085 {
2086         struct channel *pch = chan->ppp;
2087
2088         if (!pch)
2089                 return;
2090         ppp_channel_push(pch);
2091 }
2092
2093 /*
2094  * Compression control.
2095  */
2096
2097 /* Process the PPPIOCSCOMPRESS ioctl. */
2098 static int
2099 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2100 {
2101         int err;
2102         struct compressor *cp, *ocomp;
2103         struct ppp_option_data data;
2104         void *state, *ostate;
2105         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2106
2107         err = -EFAULT;
2108         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2109             || (data.length <= CCP_MAX_OPTION_LENGTH
2110                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2111                 goto out;
2112         err = -EINVAL;
2113         if (data.length > CCP_MAX_OPTION_LENGTH
2114             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2115                 goto out;
2116
2117         cp = try_then_request_module(
2118                 find_compressor(ccp_option[0]),
2119                 "ppp-compress-%d", ccp_option[0]);
2120         if (!cp)
2121                 goto out;
2122
2123         err = -ENOBUFS;
2124         if (data.transmit) {
2125                 state = cp->comp_alloc(ccp_option, data.length);
2126                 if (state) {
2127                         ppp_xmit_lock(ppp);
2128                         ppp->xstate &= ~SC_COMP_RUN;
2129                         ocomp = ppp->xcomp;
2130                         ostate = ppp->xc_state;
2131                         ppp->xcomp = cp;
2132                         ppp->xc_state = state;
2133                         ppp_xmit_unlock(ppp);
2134                         if (ostate) {
2135                                 ocomp->comp_free(ostate);
2136                                 module_put(ocomp->owner);
2137                         }
2138                         err = 0;
2139                 } else
2140                         module_put(cp->owner);
2141
2142         } else {
2143                 state = cp->decomp_alloc(ccp_option, data.length);
2144                 if (state) {
2145                         ppp_recv_lock(ppp);
2146                         ppp->rstate &= ~SC_DECOMP_RUN;
2147                         ocomp = ppp->rcomp;
2148                         ostate = ppp->rc_state;
2149                         ppp->rcomp = cp;
2150                         ppp->rc_state = state;
2151                         ppp_recv_unlock(ppp);
2152                         if (ostate) {
2153                                 ocomp->decomp_free(ostate);
2154                                 module_put(ocomp->owner);
2155                         }
2156                         err = 0;
2157                 } else
2158                         module_put(cp->owner);
2159         }
2160
2161  out:
2162         return err;
2163 }
2164
2165 /*
2166  * Look at a CCP packet and update our state accordingly.
2167  * We assume the caller has the xmit or recv path locked.
2168  */
2169 static void
2170 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2171 {
2172         unsigned char *dp;
2173         int len;
2174
2175         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2176                 return; /* no header */
2177         dp = skb->data + 2;
2178
2179         switch (CCP_CODE(dp)) {
2180         case CCP_CONFREQ:
2181
2182                 /* A ConfReq starts negotiation of compression
2183                  * in one direction of transmission,
2184                  * and hence brings it down...but which way?
2185                  *
2186                  * Remember:
2187                  * A ConfReq indicates what the sender would like to receive
2188                  */
2189                 if(inbound)
2190                         /* He is proposing what I should send */
2191                         ppp->xstate &= ~SC_COMP_RUN;
2192                 else
2193                         /* I am proposing to what he should send */
2194                         ppp->rstate &= ~SC_DECOMP_RUN;
2195
2196                 break;
2197
2198         case CCP_TERMREQ:
2199         case CCP_TERMACK:
2200                 /*
2201                  * CCP is going down, both directions of transmission
2202                  */
2203                 ppp->rstate &= ~SC_DECOMP_RUN;
2204                 ppp->xstate &= ~SC_COMP_RUN;
2205                 break;
2206
2207         case CCP_CONFACK:
2208                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2209                         break;
2210                 len = CCP_LENGTH(dp);
2211                 if (!pskb_may_pull(skb, len + 2))
2212                         return;         /* too short */
2213                 dp += CCP_HDRLEN;
2214                 len -= CCP_HDRLEN;
2215                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2216                         break;
2217                 if (inbound) {
2218                         /* we will start receiving compressed packets */
2219                         if (!ppp->rc_state)
2220                                 break;
2221                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2222                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2223                                 ppp->rstate |= SC_DECOMP_RUN;
2224                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2225                         }
2226                 } else {
2227                         /* we will soon start sending compressed packets */
2228                         if (!ppp->xc_state)
2229                                 break;
2230                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2231                                         ppp->file.index, 0, ppp->debug))
2232                                 ppp->xstate |= SC_COMP_RUN;
2233                 }
2234                 break;
2235
2236         case CCP_RESETACK:
2237                 /* reset the [de]compressor */
2238                 if ((ppp->flags & SC_CCP_UP) == 0)
2239                         break;
2240                 if (inbound) {
2241                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2242                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2243                                 ppp->rstate &= ~SC_DC_ERROR;
2244                         }
2245                 } else {
2246                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2247                                 ppp->xcomp->comp_reset(ppp->xc_state);
2248                 }
2249                 break;
2250         }
2251 }
2252
2253 /* Free up compression resources. */
2254 static void
2255 ppp_ccp_closed(struct ppp *ppp)
2256 {
2257         void *xstate, *rstate;
2258         struct compressor *xcomp, *rcomp;
2259
2260         ppp_lock(ppp);
2261         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2262         ppp->xstate = 0;
2263         xcomp = ppp->xcomp;
2264         xstate = ppp->xc_state;
2265         ppp->xc_state = NULL;
2266         ppp->rstate = 0;
2267         rcomp = ppp->rcomp;
2268         rstate = ppp->rc_state;
2269         ppp->rc_state = NULL;
2270         ppp_unlock(ppp);
2271
2272         if (xstate) {
2273                 xcomp->comp_free(xstate);
2274                 module_put(xcomp->owner);
2275         }
2276         if (rstate) {
2277                 rcomp->decomp_free(rstate);
2278                 module_put(rcomp->owner);
2279         }
2280 }
2281
2282 /* List of compressors. */
2283 static LIST_HEAD(compressor_list);
2284 static DEFINE_SPINLOCK(compressor_list_lock);
2285
2286 struct compressor_entry {
2287         struct list_head list;
2288         struct compressor *comp;
2289 };
2290
2291 static struct compressor_entry *
2292 find_comp_entry(int proto)
2293 {
2294         struct compressor_entry *ce;
2295
2296         list_for_each_entry(ce, &compressor_list, list) {
2297                 if (ce->comp->compress_proto == proto)
2298                         return ce;
2299         }
2300         return NULL;
2301 }
2302
2303 /* Register a compressor */
2304 int
2305 ppp_register_compressor(struct compressor *cp)
2306 {
2307         struct compressor_entry *ce;
2308         int ret;
2309         spin_lock(&compressor_list_lock);
2310         ret = -EEXIST;
2311         if (find_comp_entry(cp->compress_proto))
2312                 goto out;
2313         ret = -ENOMEM;
2314         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2315         if (!ce)
2316                 goto out;
2317         ret = 0;
2318         ce->comp = cp;
2319         list_add(&ce->list, &compressor_list);
2320  out:
2321         spin_unlock(&compressor_list_lock);
2322         return ret;
2323 }
2324
2325 /* Unregister a compressor */
2326 void
2327 ppp_unregister_compressor(struct compressor *cp)
2328 {
2329         struct compressor_entry *ce;
2330
2331         spin_lock(&compressor_list_lock);
2332         ce = find_comp_entry(cp->compress_proto);
2333         if (ce && ce->comp == cp) {
2334                 list_del(&ce->list);
2335                 kfree(ce);
2336         }
2337         spin_unlock(&compressor_list_lock);
2338 }
2339
2340 /* Find a compressor. */
2341 static struct compressor *
2342 find_compressor(int type)
2343 {
2344         struct compressor_entry *ce;
2345         struct compressor *cp = NULL;
2346
2347         spin_lock(&compressor_list_lock);
2348         ce = find_comp_entry(type);
2349         if (ce) {
2350                 cp = ce->comp;
2351                 if (!try_module_get(cp->owner))
2352                         cp = NULL;
2353         }
2354         spin_unlock(&compressor_list_lock);
2355         return cp;
2356 }
2357
2358 /*
2359  * Miscelleneous stuff.
2360  */
2361
2362 static void
2363 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2364 {
2365         struct slcompress *vj = ppp->vj;
2366
2367         memset(st, 0, sizeof(*st));
2368         st->p.ppp_ipackets = ppp->dev->stats.rx_packets;
2369         st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2370         st->p.ppp_ibytes = ppp->dev->stats.rx_bytes;
2371         st->p.ppp_opackets = ppp->dev->stats.tx_packets;
2372         st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2373         st->p.ppp_obytes = ppp->dev->stats.tx_bytes;
2374         if (!vj)
2375                 return;
2376         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2377         st->vj.vjs_compressed = vj->sls_o_compressed;
2378         st->vj.vjs_searches = vj->sls_o_searches;
2379         st->vj.vjs_misses = vj->sls_o_misses;
2380         st->vj.vjs_errorin = vj->sls_i_error;
2381         st->vj.vjs_tossed = vj->sls_i_tossed;
2382         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2383         st->vj.vjs_compressedin = vj->sls_i_compressed;
2384 }
2385
2386 /*
2387  * Stuff for handling the lists of ppp units and channels
2388  * and for initialization.
2389  */
2390
2391 /*
2392  * Create a new ppp interface unit.  Fails if it can't allocate memory
2393  * or if there is already a unit with the requested number.
2394  * unit == -1 means allocate a new number.
2395  */
2396 static struct ppp *
2397 ppp_create_interface(int unit, int *retp)
2398 {
2399         struct ppp *ppp;
2400         struct net_device *dev = NULL;
2401         int ret = -ENOMEM;
2402         int i;
2403
2404         dev = alloc_netdev(sizeof(struct ppp), "", ppp_setup);
2405         if (!dev)
2406                 goto out1;
2407
2408         ppp = netdev_priv(dev);
2409         ppp->dev = dev;
2410         ppp->mru = PPP_MRU;
2411         init_ppp_file(&ppp->file, INTERFACE);
2412         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2413         for (i = 0; i < NUM_NP; ++i)
2414                 ppp->npmode[i] = NPMODE_PASS;
2415         INIT_LIST_HEAD(&ppp->channels);
2416         spin_lock_init(&ppp->rlock);
2417         spin_lock_init(&ppp->wlock);
2418 #ifdef CONFIG_PPP_MULTILINK
2419         ppp->minseq = -1;
2420         skb_queue_head_init(&ppp->mrq);
2421 #endif /* CONFIG_PPP_MULTILINK */
2422
2423         ret = -EEXIST;
2424         mutex_lock(&all_ppp_mutex);
2425
2426         if (unit < 0) {
2427                 unit = unit_get(&ppp_units_idr, ppp);
2428                 if (unit < 0) {
2429                         *retp = unit;
2430                         goto out2;
2431                 }
2432         } else {
2433                 if (unit_find(&ppp_units_idr, unit))
2434                         goto out2; /* unit already exists */
2435                 else {
2436                         /* darn, someone is cheating us? */
2437                         *retp = -EINVAL;
2438                         goto out2;
2439                 }
2440         }
2441
2442         /* Initialize the new ppp unit */
2443         ppp->file.index = unit;
2444         sprintf(dev->name, "ppp%d", unit);
2445
2446         ret = register_netdev(dev);
2447         if (ret != 0) {
2448                 unit_put(&ppp_units_idr, unit);
2449                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2450                        dev->name, ret);
2451                 goto out2;
2452         }
2453
2454         atomic_inc(&ppp_unit_count);
2455         mutex_unlock(&all_ppp_mutex);
2456
2457         *retp = 0;
2458         return ppp;
2459
2460 out2:
2461         mutex_unlock(&all_ppp_mutex);
2462         free_netdev(dev);
2463 out1:
2464         *retp = ret;
2465         return NULL;
2466 }
2467
2468 /*
2469  * Initialize a ppp_file structure.
2470  */
2471 static void
2472 init_ppp_file(struct ppp_file *pf, int kind)
2473 {
2474         pf->kind = kind;
2475         skb_queue_head_init(&pf->xq);
2476         skb_queue_head_init(&pf->rq);
2477         atomic_set(&pf->refcnt, 1);
2478         init_waitqueue_head(&pf->rwait);
2479 }
2480
2481 /*
2482  * Take down a ppp interface unit - called when the owning file
2483  * (the one that created the unit) is closed or detached.
2484  */
2485 static void ppp_shutdown_interface(struct ppp *ppp)
2486 {
2487         mutex_lock(&all_ppp_mutex);
2488         /* This will call dev_close() for us. */
2489         ppp_lock(ppp);
2490         if (!ppp->closing) {
2491                 ppp->closing = 1;
2492                 ppp_unlock(ppp);
2493                 unregister_netdev(ppp->dev);
2494         } else
2495                 ppp_unlock(ppp);
2496
2497         unit_put(&ppp_units_idr, ppp->file.index);
2498         ppp->file.dead = 1;
2499         ppp->owner = NULL;
2500         wake_up_interruptible(&ppp->file.rwait);
2501         mutex_unlock(&all_ppp_mutex);
2502 }
2503
2504 /*
2505  * Free the memory used by a ppp unit.  This is only called once
2506  * there are no channels connected to the unit and no file structs
2507  * that reference the unit.
2508  */
2509 static void ppp_destroy_interface(struct ppp *ppp)
2510 {
2511         atomic_dec(&ppp_unit_count);
2512
2513         if (!ppp->file.dead || ppp->n_channels) {
2514                 /* "can't happen" */
2515                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2516                        "n_channels=%d !\n", ppp, ppp->file.dead,
2517                        ppp->n_channels);
2518                 return;
2519         }
2520
2521         ppp_ccp_closed(ppp);
2522         if (ppp->vj) {
2523                 slhc_free(ppp->vj);
2524                 ppp->vj = NULL;
2525         }
2526         skb_queue_purge(&ppp->file.xq);
2527         skb_queue_purge(&ppp->file.rq);
2528 #ifdef CONFIG_PPP_MULTILINK
2529         skb_queue_purge(&ppp->mrq);
2530 #endif /* CONFIG_PPP_MULTILINK */
2531 #ifdef CONFIG_PPP_FILTER
2532         kfree(ppp->pass_filter);
2533         ppp->pass_filter = NULL;
2534         kfree(ppp->active_filter);
2535         ppp->active_filter = NULL;
2536 #endif /* CONFIG_PPP_FILTER */
2537
2538         if (ppp->xmit_pending)
2539                 kfree_skb(ppp->xmit_pending);
2540
2541         free_netdev(ppp->dev);
2542 }
2543
2544 /*
2545  * Locate an existing ppp unit.
2546  * The caller should have locked the all_ppp_mutex.
2547  */
2548 static struct ppp *
2549 ppp_find_unit(int unit)
2550 {
2551         return unit_find(&ppp_units_idr, unit);
2552 }
2553
2554 /*
2555  * Locate an existing ppp channel.
2556  * The caller should have locked the all_channels_lock.
2557  * First we look in the new_channels list, then in the
2558  * all_channels list.  If found in the new_channels list,
2559  * we move it to the all_channels list.  This is for speed
2560  * when we have a lot of channels in use.
2561  */
2562 static struct channel *
2563 ppp_find_channel(int unit)
2564 {
2565         struct channel *pch;
2566
2567         list_for_each_entry(pch, &new_channels, list) {
2568                 if (pch->file.index == unit) {
2569                         list_move(&pch->list, &all_channels);
2570                         return pch;
2571                 }
2572         }
2573         list_for_each_entry(pch, &all_channels, list) {
2574                 if (pch->file.index == unit)
2575                         return pch;
2576         }
2577         return NULL;
2578 }
2579
2580 /*
2581  * Connect a PPP channel to a PPP interface unit.
2582  */
2583 static int
2584 ppp_connect_channel(struct channel *pch, int unit)
2585 {
2586         struct ppp *ppp;
2587         int ret = -ENXIO;
2588         int hdrlen;
2589
2590         mutex_lock(&all_ppp_mutex);
2591         ppp = ppp_find_unit(unit);
2592         if (!ppp)
2593                 goto out;
2594         write_lock_bh(&pch->upl);
2595         ret = -EINVAL;
2596         if (pch->ppp)
2597                 goto outl;
2598
2599         ppp_lock(ppp);
2600         if (pch->file.hdrlen > ppp->file.hdrlen)
2601                 ppp->file.hdrlen = pch->file.hdrlen;
2602         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2603         if (hdrlen > ppp->dev->hard_header_len)
2604                 ppp->dev->hard_header_len = hdrlen;
2605         list_add_tail(&pch->clist, &ppp->channels);
2606         ++ppp->n_channels;
2607         pch->ppp = ppp;
2608         atomic_inc(&ppp->file.refcnt);
2609         ppp_unlock(ppp);
2610         ret = 0;
2611
2612  outl:
2613         write_unlock_bh(&pch->upl);
2614  out:
2615         mutex_unlock(&all_ppp_mutex);
2616         return ret;
2617 }
2618
2619 /*
2620  * Disconnect a channel from its ppp unit.
2621  */
2622 static int
2623 ppp_disconnect_channel(struct channel *pch)
2624 {
2625         struct ppp *ppp;
2626         int err = -EINVAL;
2627
2628         write_lock_bh(&pch->upl);
2629         ppp = pch->ppp;
2630         pch->ppp = NULL;
2631         write_unlock_bh(&pch->upl);
2632         if (ppp) {
2633                 /* remove it from the ppp unit's list */
2634                 ppp_lock(ppp);
2635                 list_del(&pch->clist);
2636                 if (--ppp->n_channels == 0)
2637                         wake_up_interruptible(&ppp->file.rwait);
2638                 ppp_unlock(ppp);
2639                 if (atomic_dec_and_test(&ppp->file.refcnt))
2640                         ppp_destroy_interface(ppp);
2641                 err = 0;
2642         }
2643         return err;
2644 }
2645
2646 /*
2647  * Free up the resources used by a ppp channel.
2648  */
2649 static void ppp_destroy_channel(struct channel *pch)
2650 {
2651         atomic_dec(&channel_count);
2652
2653         if (!pch->file.dead) {
2654                 /* "can't happen" */
2655                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2656                        pch);
2657                 return;
2658         }
2659         skb_queue_purge(&pch->file.xq);
2660         skb_queue_purge(&pch->file.rq);
2661         kfree(pch);
2662 }
2663
2664 static void __exit ppp_cleanup(void)
2665 {
2666         /* should never happen */
2667         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2668                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2669         unregister_chrdev(PPP_MAJOR, "ppp");
2670         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2671         class_destroy(ppp_class);
2672         idr_destroy(&ppp_units_idr);
2673 }
2674
2675 /*
2676  * Units handling. Caller must protect concurrent access
2677  * by holding all_ppp_mutex
2678  */
2679
2680 /* get new free unit number and associate pointer with it */
2681 static int unit_get(struct idr *p, void *ptr)
2682 {
2683         int unit, err;
2684
2685 again:
2686         if (idr_pre_get(p, GFP_KERNEL) == 0) {
2687                 printk(KERN_ERR "Out of memory expanding drawable idr\n");
2688                 return -ENOMEM;
2689         }
2690
2691         err = idr_get_new_above(p, ptr, 0, &unit);
2692         if (err == -EAGAIN)
2693                 goto again;
2694
2695         return unit;
2696 }
2697
2698 /* put unit number back to a pool */
2699 static void unit_put(struct idr *p, int n)
2700 {
2701         idr_remove(p, n);
2702 }
2703
2704 /* get pointer associated with the number */
2705 static void *unit_find(struct idr *p, int n)
2706 {
2707         return idr_find(p, n);
2708 }
2709
2710 /* Module/initialization stuff */
2711
2712 module_init(ppp_init);
2713 module_exit(ppp_cleanup);
2714
2715 EXPORT_SYMBOL(ppp_register_channel);
2716 EXPORT_SYMBOL(ppp_unregister_channel);
2717 EXPORT_SYMBOL(ppp_channel_index);
2718 EXPORT_SYMBOL(ppp_unit_number);
2719 EXPORT_SYMBOL(ppp_input);
2720 EXPORT_SYMBOL(ppp_input_error);
2721 EXPORT_SYMBOL(ppp_output_wakeup);
2722 EXPORT_SYMBOL(ppp_register_compressor);
2723 EXPORT_SYMBOL(ppp_unregister_compressor);
2724 MODULE_LICENSE("GPL");
2725 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2726 MODULE_ALIAS("/dev/ppp");