drivers/net/ppp_generic.c

   1 /*
   2  * Generic PPP layer for Linux.
   3  *
   4  * Copyright 1999-2002 Paul Mackerras.
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  *
  11  * The generic PPP layer handles the PPP network interfaces, the
  12  * /dev/ppp device, packet and VJ compression, and multilink.
  13  * It talks to PPP `channels' via the interface defined in
  14  * include/linux/ppp_channel.h.  Channels provide the basic means for
  15  * sending and receiving PPP frames on some kind of communications
  16  * channel.
  17  *
  18  * Part of the code in this driver was inspired by the old async-only
  19  * PPP driver, written by Michael Callahan and Al Longyear, and
  20  * subsequently hacked by Paul Mackerras.
  21  *
  22  * ==FILEVERSION 20041108==
  23  */
  24
  25 #include <linux/module.h>
  26 #include <linux/kernel.h>
  27 #include <linux/kmod.h>
  28 #include <linux/init.h>
  29 #include <linux/list.h>
  30 #include <linux/netdevice.h>
  31 #include <linux/poll.h>
  32 #include <linux/ppp_defs.h>
  33 #include <linux/filter.h>
  34 #include <linux/if_ppp.h>
  35 #include <linux/ppp_channel.h>
  36 #include <linux/ppp-comp.h>
  37 #include <linux/skbuff.h>
  38 #include <linux/rtnetlink.h>
  39 #include <linux/if_arp.h>
  40 #include <linux/ip.h>
  41 #include <linux/tcp.h>
  42 #include <linux/spinlock.h>
  43 #include <linux/smp_lock.h>
  44 #include <linux/rwsem.h>
  45 #include <linux/stddef.h>
  46 #include <linux/device.h>
  47 #include <linux/mutex.h>
  48 #include <net/slhc_vj.h>
  49 #include <asm/atomic.h>
  50
  51 #define PPP_VERSION     "2.4.2"
  52
  53 /*
  54  * Network protocols we support.
  55  */
  56 #define NP_IP   0               /* Internet Protocol V4 */
  57 #define NP_IPV6 1               /* Internet Protocol V6 */
  58 #define NP_IPX  2               /* IPX protocol */
  59 #define NP_AT   3               /* Appletalk protocol */
  60 #define NP_MPLS_UC 4            /* MPLS unicast */
  61 #define NP_MPLS_MC 5            /* MPLS multicast */
  62 #define NUM_NP  6               /* Number of NPs. */
  63
  64 #define MPHDRLEN        6       /* multilink protocol header length */
  65 #define MPHDRLEN_SSN    4       /* ditto with short sequence numbers */
  66 #define MIN_FRAG_SIZE   64
  67
  68 /*
  69  * An instance of /dev/ppp can be associated with either a ppp
  70  * interface unit or a ppp channel.  In both cases, file->private_data
  71  * points to one of these.
  72  */
  73 struct ppp_file {
  74         enum {
  75                 INTERFACE=1, CHANNEL
  76         }               kind;
  77         struct sk_buff_head xq;         /* pppd transmit queue */
  78         struct sk_buff_head rq;         /* receive queue for pppd */
  79         wait_queue_head_t rwait;        /* for poll on reading /dev/ppp */
  80         atomic_t        refcnt;         /* # refs (incl /dev/ppp attached) */
  81         int             hdrlen;         /* space to leave for headers */
  82         int             index;          /* interface unit / channel number */
  83         int             dead;           /* unit/channel has been shut down */
  84 };
  85
  86 #define PF_TO_X(pf, X)          ((X *)((char *)(pf) - offsetof(X, file)))
  87
  88 #define PF_TO_PPP(pf)           PF_TO_X(pf, struct ppp)
  89 #define PF_TO_CHANNEL(pf)       PF_TO_X(pf, struct channel)
  90
  91 #define ROUNDUP(n, x)           (((n) + (x) - 1) / (x))
  92
  93 /*
  94  * Data structure describing one ppp unit.
  95  * A ppp unit corresponds to a ppp network interface device
  96  * and represents a multilink bundle.
  97  * It can have 0 or more ppp channels connected to it.
  98  */
  99 struct ppp {
 100         struct ppp_file file;           /* stuff for read/write/poll 0 */
 101         struct file     *owner;         /* file that owns this unit 48 */
 102         struct list_head channels;      /* list of attached channels 4c */
 103         int             n_channels;     /* how many channels are attached 54 */
 104         spinlock_t      rlock;          /* lock for receive side 58 */
 105         spinlock_t      wlock;          /* lock for transmit side 5c */
 106         int             mru;            /* max receive unit 60 */
 107         unsigned int    flags;          /* control bits 64 */
 108         unsigned int    xstate;         /* transmit state bits 68 */
 109         unsigned int    rstate;         /* receive state bits 6c */
 110         int             debug;          /* debug flags 70 */
 111         struct slcompress *vj;          /* state for VJ header compression */
 112         enum NPmode     npmode[NUM_NP]; /* what to do with each net proto 78 */
 113         struct sk_buff  *xmit_pending;  /* a packet ready to go out 88 */
 114         struct compressor *xcomp;       /* transmit packet compressor 8c */
 115         void            *xc_state;      /* its internal state 90 */
 116         struct compressor *rcomp;       /* receive decompressor 94 */
 117         void            *rc_state;      /* its internal state 98 */
 118         unsigned long   last_xmit;      /* jiffies when last pkt sent 9c */
 119         unsigned long   last_recv;      /* jiffies when last pkt rcvd a0 */
 120         struct net_device *dev;         /* network interface device a4 */
 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         struct net_device_stats stats;  /* statistics */
 130 #ifdef CONFIG_PPP_FILTER
 131         struct sock_filter *pass_filter;        /* filter for packets to pass */
 132         struct sock_filter *active_filter;/* filter for pkts to reset idle */
 133         unsigned pass_len, active_len;
 134 #endif /* CONFIG_PPP_FILTER */
 135 };
 136
 137 /*
 138  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
 139  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
 140  * SC_MUST_COMP
 141  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
 142  * Bits in xstate: SC_COMP_RUN
 143  */
 144 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
 145                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
 146                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
 147
 148 /*
 149  * Private data structure for each channel.
 150  * This includes the data structure used for multilink.
 151  */
 152 struct channel {
 153         struct ppp_file file;           /* stuff for read/write/poll */
 154         struct list_head list;          /* link in all/new_channels list */
 155         struct ppp_channel *chan;       /* public channel data structure */
 156         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
 157         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
 158         struct ppp      *ppp;           /* ppp unit we're connected to */
 159         struct list_head clist;         /* link in list of channels per unit */
 160         rwlock_t        upl;            /* protects `ppp' */
 161 #ifdef CONFIG_PPP_MULTILINK
 162         u8              avail;          /* flag used in multilink stuff */
 163         u8              had_frag;       /* >= 1 fragments have been sent */
 164         u32             lastseq;        /* MP: last sequence # received */
 165 #endif /* CONFIG_PPP_MULTILINK */
 166 };
 167
 168 /*
 169  * SMP locking issues:
 170  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
 171  * list and the ppp.n_channels field, you need to take both locks
 172  * before you modify them.
 173  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
 174  * channel.downl.
 175  */
 176
 177 /*
 178  * A cardmap represents a mapping from unsigned integers to pointers,
 179  * and provides a fast "find lowest unused number" operation.
 180  * It uses a broad (32-way) tree with a bitmap at each level.
 181  * It is designed to be space-efficient for small numbers of entries
 182  * and time-efficient for large numbers of entries.
 183  */
 184 #define CARDMAP_ORDER   5
 185 #define CARDMAP_WIDTH   (1U << CARDMAP_ORDER)
 186 #define CARDMAP_MASK    (CARDMAP_WIDTH - 1)
 187
 188 struct cardmap {
 189         int shift;
 190         unsigned long inuse;
 191         struct cardmap *parent;
 192         void *ptr[CARDMAP_WIDTH];
 193 };
 194 static void *cardmap_get(struct cardmap *map, unsigned int nr);
 195 static int cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
 196 static unsigned int cardmap_find_first_free(struct cardmap *map);
 197 static void cardmap_destroy(struct cardmap **map);
 198
 199 /*
 200  * all_ppp_mutex protects the all_ppp_units mapping.
 201  * It also ensures that finding a ppp unit in the all_ppp_units map
 202  * and updating its file.refcnt field is atomic.
 203  */
 204 static DEFINE_MUTEX(all_ppp_mutex);
 205 static struct cardmap *all_ppp_units;
 206 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 207
 208 /*
 209  * all_channels_lock protects all_channels and last_channel_index,
 210  * and the atomicity of find a channel and updating its file.refcnt
 211  * field.
 212  */
 213 static DEFINE_SPINLOCK(all_channels_lock);
 214 static LIST_HEAD(all_channels);
 215 static LIST_HEAD(new_channels);
 216 static int last_channel_index;
 217 static atomic_t channel_count = ATOMIC_INIT(0);
 218
 219 /* Get the PPP protocol number from a skb */
 220 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
 221
 222 /* We limit the length of ppp->file.rq to this (arbitrary) value */
 223 #define PPP_MAX_RQLEN   32
 224
 225 /*
 226  * Maximum number of multilink fragments queued up.
 227  * This has to be large enough to cope with the maximum latency of
 228  * the slowest channel relative to the others.  Strictly it should
 229  * depend on the number of channels and their characteristics.
 230  */
 231 #define PPP_MP_MAX_QLEN 128
 232
 233 /* Multilink header bits. */
 234 #define B       0x80            /* this fragment begins a packet */
 235 #define E       0x40            /* this fragment ends a packet */
 236
 237 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
 238 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
 239 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
 240
 241 /* Prototypes. */
 242 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 243                                 unsigned int cmd, unsigned long arg);
 244 static void ppp_xmit_process(struct ppp *ppp);
 245 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
 246 static void ppp_push(struct ppp *ppp);
 247 static void ppp_channel_push(struct channel *pch);
 248 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
 249                               struct channel *pch);
 250 static void ppp_receive_error(struct ppp *ppp);
 251 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
 252 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
 253                                             struct sk_buff *skb);
 254 #ifdef CONFIG_PPP_MULTILINK
 255 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
 256                                 struct channel *pch);
 257 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
 258 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
 259 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
 260 #endif /* CONFIG_PPP_MULTILINK */
 261 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
 262 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
 263 static void ppp_ccp_closed(struct ppp *ppp);
 264 static struct compressor *find_compressor(int type);
 265 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
 266 static struct ppp *ppp_create_interface(int unit, int *retp);
 267 static void init_ppp_file(struct ppp_file *pf, int kind);
 268 static void ppp_shutdown_interface(struct ppp *ppp);
 269 static void ppp_destroy_interface(struct ppp *ppp);
 270 static struct ppp *ppp_find_unit(int unit);
 271 static struct channel *ppp_find_channel(int unit);
 272 static int ppp_connect_channel(struct channel *pch, int unit);
 273 static int ppp_disconnect_channel(struct channel *pch);
 274 static void ppp_destroy_channel(struct channel *pch);
 275
 276 static struct class *ppp_class;
 277
 278 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
 279 static inline int proto_to_npindex(int proto)
 280 {
 281         switch (proto) {
 282         case PPP_IP:
 283                 return NP_IP;
 284         case PPP_IPV6:
 285                 return NP_IPV6;
 286         case PPP_IPX:
 287                 return NP_IPX;
 288         case PPP_AT:
 289                 return NP_AT;
 290         case PPP_MPLS_UC:
 291                 return NP_MPLS_UC;
 292         case PPP_MPLS_MC:
 293                 return NP_MPLS_MC;
 294         }
 295         return -EINVAL;
 296 }
 297
 298 /* Translates an NP index into a PPP protocol number */
 299 static const int npindex_to_proto[NUM_NP] = {
 300         PPP_IP,
 301         PPP_IPV6,
 302         PPP_IPX,
 303         PPP_AT,
 304         PPP_MPLS_UC,
 305         PPP_MPLS_MC,
 306 };
 307
 308 /* Translates an ethertype into an NP index */
 309 static inline int ethertype_to_npindex(int ethertype)
 310 {
 311         switch (ethertype) {
 312         case ETH_P_IP:
 313                 return NP_IP;
 314         case ETH_P_IPV6:
 315                 return NP_IPV6;
 316         case ETH_P_IPX:
 317                 return NP_IPX;
 318         case ETH_P_PPPTALK:
 319         case ETH_P_ATALK:
 320                 return NP_AT;
 321         case ETH_P_MPLS_UC:
 322                 return NP_MPLS_UC;
 323         case ETH_P_MPLS_MC:
 324                 return NP_MPLS_MC;
 325         }
 326         return -1;
 327 }
 328
 329 /* Translates an NP index into an ethertype */
 330 static const int npindex_to_ethertype[NUM_NP] = {
 331         ETH_P_IP,
 332         ETH_P_IPV6,
 333         ETH_P_IPX,
 334         ETH_P_PPPTALK,
 335         ETH_P_MPLS_UC,
 336         ETH_P_MPLS_MC,
 337 };
 338
 339 /*
 340  * Locking shorthand.
 341  */
 342 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
 343 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
 344 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
 345 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
 346 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
 347                                      ppp_recv_lock(ppp); } while (0)
 348 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
 349                                      ppp_xmit_unlock(ppp); } while (0)
 350
 351 /*
 352  * /dev/ppp device routines.
 353  * The /dev/ppp device is used by pppd to control the ppp unit.
 354  * It supports the read, write, ioctl and poll functions.
 355  * Open instances of /dev/ppp can be in one of three states:
 356  * unattached, attached to a ppp unit, or attached to a ppp channel.
 357  */
 358 static int ppp_open(struct inode *inode, struct file *file)
 359 {
 360         /*
 361          * This could (should?) be enforced by the permissions on /dev/ppp.
 362          */
 363         if (!capable(CAP_NET_ADMIN))
 364                 return -EPERM;
 365         return 0;
 366 }
 367
 368 static int ppp_release(struct inode *inode, struct file *file)
 369 {
 370         struct ppp_file *pf = file->private_data;
 371         struct ppp *ppp;
 372
 373         if (pf != 0) {
 374                 file->private_data = NULL;
 375                 if (pf->kind == INTERFACE) {
 376                         ppp = PF_TO_PPP(pf);
 377                         if (file == ppp->owner)
 378                                 ppp_shutdown_interface(ppp);
 379                 }
 380                 if (atomic_dec_and_test(&pf->refcnt)) {
 381                         switch (pf->kind) {
 382                         case INTERFACE:
 383                                 ppp_destroy_interface(PF_TO_PPP(pf));
 384                                 break;
 385                         case CHANNEL:
 386                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
 387                                 break;
 388                         }
 389                 }
 390         }
 391         return 0;
 392 }
 393
 394 static ssize_t ppp_read(struct file *file, char __user *buf,
 395                         size_t count, loff_t *ppos)
 396 {
 397         struct ppp_file *pf = file->private_data;
 398         DECLARE_WAITQUEUE(wait, current);
 399         ssize_t ret;
 400         struct sk_buff *skb = NULL;
 401
 402         ret = count;
 403
 404         if (pf == 0)
 405                 return -ENXIO;
 406         add_wait_queue(&pf->rwait, &wait);
 407         for (;;) {
 408                 set_current_state(TASK_INTERRUPTIBLE);
 409                 skb = skb_dequeue(&pf->rq);
 410                 if (skb)
 411                         break;
 412                 ret = 0;
 413                 if (pf->dead)
 414                         break;
 415                 if (pf->kind == INTERFACE) {
 416                         /*
 417                          * Return 0 (EOF) on an interface that has no
 418                          * channels connected, unless it is looping
 419                          * network traffic (demand mode).
 420                          */
 421                         struct ppp *ppp = PF_TO_PPP(pf);
 422                         if (ppp->n_channels == 0
 423                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 424                                 break;
 425                 }
 426                 ret = -EAGAIN;
 427                 if (file->f_flags & O_NONBLOCK)
 428                         break;
 429                 ret = -ERESTARTSYS;
 430                 if (signal_pending(current))
 431                         break;
 432                 schedule();
 433         }
 434         set_current_state(TASK_RUNNING);
 435         remove_wait_queue(&pf->rwait, &wait);
 436
 437         if (skb == 0)
 438                 goto out;
 439
 440         ret = -EOVERFLOW;
 441         if (skb->len > count)
 442                 goto outf;
 443         ret = -EFAULT;
 444         if (copy_to_user(buf, skb->data, skb->len))
 445                 goto outf;
 446         ret = skb->len;
 447
 448  outf:
 449         kfree_skb(skb);
 450  out:
 451         return ret;
 452 }
 453
 454 static ssize_t ppp_write(struct file *file, const char __user *buf,
 455                          size_t count, loff_t *ppos)
 456 {
 457         struct ppp_file *pf = file->private_data;
 458         struct sk_buff *skb;
 459         ssize_t ret;
 460
 461         if (pf == 0)
 462                 return -ENXIO;
 463         ret = -ENOMEM;
 464         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
 465         if (skb == 0)
 466                 goto out;
 467         skb_reserve(skb, pf->hdrlen);
 468         ret = -EFAULT;
 469         if (copy_from_user(skb_put(skb, count), buf, count)) {
 470                 kfree_skb(skb);
 471                 goto out;
 472         }
 473
 474         skb_queue_tail(&pf->xq, skb);
 475
 476         switch (pf->kind) {
 477         case INTERFACE:
 478                 ppp_xmit_process(PF_TO_PPP(pf));
 479                 break;
 480         case CHANNEL:
 481                 ppp_channel_push(PF_TO_CHANNEL(pf));
 482                 break;
 483         }
 484
 485         ret = count;
 486
 487  out:
 488         return ret;
 489 }
 490
 491 /* No kernel lock - fine */
 492 static unsigned int ppp_poll(struct file *file, poll_table *wait)
 493 {
 494         struct ppp_file *pf = file->private_data;
 495         unsigned int mask;
 496
 497         if (pf == 0)
 498                 return 0;
 499         poll_wait(file, &pf->rwait, wait);
 500         mask = POLLOUT | POLLWRNORM;
 501         if (skb_peek(&pf->rq) != 0)
 502                 mask |= POLLIN | POLLRDNORM;
 503         if (pf->dead)
 504                 mask |= POLLHUP;
 505         else if (pf->kind == INTERFACE) {
 506                 /* see comment in ppp_read */
 507                 struct ppp *ppp = PF_TO_PPP(pf);
 508                 if (ppp->n_channels == 0
 509                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 510                         mask |= POLLIN | POLLRDNORM;
 511         }
 512
 513         return mask;
 514 }
 515
 516 #ifdef CONFIG_PPP_FILTER
 517 static int get_filter(void __user *arg, struct sock_filter **p)
 518 {
 519         struct sock_fprog uprog;
 520         struct sock_filter *code = NULL;
 521         int len, err;
 522
 523         if (copy_from_user(&uprog, arg, sizeof(uprog)))
 524                 return -EFAULT;
 525
 526         if (!uprog.len) {
 527                 *p = NULL;
 528                 return 0;
 529         }
 530
 531         len = uprog.len * sizeof(struct sock_filter);
 532         code = kmalloc(len, GFP_KERNEL);
 533         if (code == NULL)
 534                 return -ENOMEM;
 535
 536         if (copy_from_user(code, uprog.filter, len)) {
 537                 kfree(code);
 538                 return -EFAULT;
 539         }
 540
 541         err = sk_chk_filter(code, uprog.len);
 542         if (err) {
 543                 kfree(code);
 544                 return err;
 545         }
 546
 547         *p = code;
 548         return uprog.len;
 549 }
 550 #endif /* CONFIG_PPP_FILTER */
 551
 552 static int ppp_ioctl(struct inode *inode, struct file *file,
 553                      unsigned int cmd, unsigned long arg)
 554 {
 555         struct ppp_file *pf = file->private_data;
 556         struct ppp *ppp;
 557         int err = -EFAULT, val, val2, i;
 558         struct ppp_idle idle;
 559         struct npioctl npi;
 560         int unit, cflags;
 561         struct slcompress *vj;
 562         void __user *argp = (void __user *)arg;
 563         int __user *p = argp;
 564
 565         if (pf == 0)
 566                 return ppp_unattached_ioctl(pf, file, cmd, arg);
 567
 568         if (cmd == PPPIOCDETACH) {
 569                 /*
 570                  * We have to be careful here... if the file descriptor
 571                  * has been dup'd, we could have another process in the
 572                  * middle of a poll using the same file *, so we had
 573                  * better not free the interface data structures -
 574                  * instead we fail the ioctl.  Even in this case, we
 575                  * shut down the interface if we are the owner of it.
 576                  * Actually, we should get rid of PPPIOCDETACH, userland
 577                  * (i.e. pppd) could achieve the same effect by closing
 578                  * this fd and reopening /dev/ppp.
 579                  */
 580                 err = -EINVAL;
 581                 if (pf->kind == INTERFACE) {
 582                         ppp = PF_TO_PPP(pf);
 583                         if (file == ppp->owner)
 584                                 ppp_shutdown_interface(ppp);
 585                 }
 586                 if (atomic_read(&file->f_count) <= 2) {
 587                         ppp_release(inode, file);
 588                         err = 0;
 589                 } else
 590                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%d\n",
 591                                atomic_read(&file->f_count));
 592                 return err;
 593         }
 594
 595         if (pf->kind == CHANNEL) {
 596                 struct channel *pch = PF_TO_CHANNEL(pf);
 597                 struct ppp_channel *chan;
 598
 599                 switch (cmd) {
 600                 case PPPIOCCONNECT:
 601                         if (get_user(unit, p))
 602                                 break;
 603                         err = ppp_connect_channel(pch, unit);
 604                         break;
 605
 606                 case PPPIOCDISCONN:
 607                         err = ppp_disconnect_channel(pch);
 608                         break;
 609
 610                 default:
 611                         down_read(&pch->chan_sem);
 612                         chan = pch->chan;
 613                         err = -ENOTTY;
 614                         if (chan && chan->ops->ioctl)
 615                                 err = chan->ops->ioctl(chan, cmd, arg);
 616                         up_read(&pch->chan_sem);
 617                 }
 618                 return err;
 619         }
 620
 621         if (pf->kind != INTERFACE) {
 622                 /* can't happen */
 623                 printk(KERN_ERR "PPP: not interface or channel??\n");
 624                 return -EINVAL;
 625         }
 626
 627         ppp = PF_TO_PPP(pf);
 628         switch (cmd) {
 629         case PPPIOCSMRU:
 630                 if (get_user(val, p))
 631                         break;
 632                 ppp->mru = val;
 633                 err = 0;
 634                 break;
 635
 636         case PPPIOCSFLAGS:
 637                 if (get_user(val, p))
 638                         break;
 639                 ppp_lock(ppp);
 640                 cflags = ppp->flags & ~val;
 641                 ppp->flags = val & SC_FLAG_BITS;
 642                 ppp_unlock(ppp);
 643                 if (cflags & SC_CCP_OPEN)
 644                         ppp_ccp_closed(ppp);
 645                 err = 0;
 646                 break;
 647
 648         case PPPIOCGFLAGS:
 649                 val = ppp->flags | ppp->xstate | ppp->rstate;
 650                 if (put_user(val, p))
 651                         break;
 652                 err = 0;
 653                 break;
 654
 655         case PPPIOCSCOMPRESS:
 656                 err = ppp_set_compress(ppp, arg);
 657                 break;
 658
 659         case PPPIOCGUNIT:
 660                 if (put_user(ppp->file.index, p))
 661                         break;
 662                 err = 0;
 663                 break;
 664
 665         case PPPIOCSDEBUG:
 666                 if (get_user(val, p))
 667                         break;
 668                 ppp->debug = val;
 669                 err = 0;
 670                 break;
 671
 672         case PPPIOCGDEBUG:
 673                 if (put_user(ppp->debug, p))
 674                         break;
 675                 err = 0;
 676                 break;
 677
 678         case PPPIOCGIDLE:
 679                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 680                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
 681                 if (copy_to_user(argp, &idle, sizeof(idle)))
 682                         break;
 683                 err = 0;
 684                 break;
 685
 686         case PPPIOCSMAXCID:
 687                 if (get_user(val, p))
 688                         break;
 689                 val2 = 15;
 690                 if ((val >> 16) != 0) {
 691                         val2 = val >> 16;
 692                         val &= 0xffff;
 693                 }
 694                 vj = slhc_init(val2+1, val+1);
 695                 if (vj == 0) {
 696                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
 697                         err = -ENOMEM;
 698                         break;
 699                 }
 700                 ppp_lock(ppp);
 701                 if (ppp->vj != 0)
 702                         slhc_free(ppp->vj);
 703                 ppp->vj = vj;
 704                 ppp_unlock(ppp);
 705                 err = 0;
 706                 break;
 707
 708         case PPPIOCGNPMODE:
 709         case PPPIOCSNPMODE:
 710                 if (copy_from_user(&npi, argp, sizeof(npi)))
 711                         break;
 712                 err = proto_to_npindex(npi.protocol);
 713                 if (err < 0)
 714                         break;
 715                 i = err;
 716                 if (cmd == PPPIOCGNPMODE) {
 717                         err = -EFAULT;
 718                         npi.mode = ppp->npmode[i];
 719                         if (copy_to_user(argp, &npi, sizeof(npi)))
 720                                 break;
 721                 } else {
 722                         ppp->npmode[i] = npi.mode;
 723                         /* we may be able to transmit more packets now (??) */
 724                         netif_wake_queue(ppp->dev);
 725                 }
 726                 err = 0;
 727                 break;
 728
 729 #ifdef CONFIG_PPP_FILTER
 730         case PPPIOCSPASS:
 731         {
 732                 struct sock_filter *code;
 733                 err = get_filter(argp, &code);
 734                 if (err >= 0) {
 735                         ppp_lock(ppp);
 736                         kfree(ppp->pass_filter);
 737                         ppp->pass_filter = code;
 738                         ppp->pass_len = err;
 739                         ppp_unlock(ppp);
 740                         err = 0;
 741                 }
 742                 break;
 743         }
 744         case PPPIOCSACTIVE:
 745         {
 746                 struct sock_filter *code;
 747                 err = get_filter(argp, &code);
 748                 if (err >= 0) {
 749                         ppp_lock(ppp);
 750                         kfree(ppp->active_filter);
 751                         ppp->active_filter = code;
 752                         ppp->active_len = err;
 753                         ppp_unlock(ppp);
 754                         err = 0;
 755                 }
 756                 break;
 757         }
 758 #endif /* CONFIG_PPP_FILTER */
 759
 760 #ifdef CONFIG_PPP_MULTILINK
 761         case PPPIOCSMRRU:
 762                 if (get_user(val, p))
 763                         break;
 764                 ppp_recv_lock(ppp);
 765                 ppp->mrru = val;
 766                 ppp_recv_unlock(ppp);
 767                 err = 0;
 768                 break;
 769 #endif /* CONFIG_PPP_MULTILINK */
 770
 771         default:
 772                 err = -ENOTTY;
 773         }
 774
 775         return err;
 776 }
 777
 778 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 779                                 unsigned int cmd, unsigned long arg)
 780 {
 781         int unit, err = -EFAULT;
 782         struct ppp *ppp;
 783         struct channel *chan;
 784         int __user *p = (int __user *)arg;
 785
 786         switch (cmd) {
 787         case PPPIOCNEWUNIT:
 788                 /* Create a new ppp unit */
 789                 if (get_user(unit, p))
 790                         break;
 791                 ppp = ppp_create_interface(unit, &err);
 792                 if (ppp == 0)
 793                         break;
 794                 file->private_data = &ppp->file;
 795                 ppp->owner = file;
 796                 err = -EFAULT;
 797                 if (put_user(ppp->file.index, p))
 798                         break;
 799                 err = 0;
 800                 break;
 801
 802         case PPPIOCATTACH:
 803                 /* Attach to an existing ppp unit */
 804                 if (get_user(unit, p))
 805                         break;
 806                 mutex_lock(&all_ppp_mutex);
 807                 err = -ENXIO;
 808                 ppp = ppp_find_unit(unit);
 809                 if (ppp != 0) {
 810                         atomic_inc(&ppp->file.refcnt);
 811                         file->private_data = &ppp->file;
 812                         err = 0;
 813                 }
 814                 mutex_unlock(&all_ppp_mutex);
 815                 break;
 816
 817         case PPPIOCATTCHAN:
 818                 if (get_user(unit, p))
 819                         break;
 820                 spin_lock_bh(&all_channels_lock);
 821                 err = -ENXIO;
 822                 chan = ppp_find_channel(unit);
 823                 if (chan != 0) {
 824                         atomic_inc(&chan->file.refcnt);
 825                         file->private_data = &chan->file;
 826                         err = 0;
 827                 }
 828                 spin_unlock_bh(&all_channels_lock);
 829                 break;
 830
 831         default:
 832                 err = -ENOTTY;
 833         }
 834         return err;
 835 }
 836
 837 static struct file_operations ppp_device_fops = {
 838         .owner          = THIS_MODULE,
 839         .read           = ppp_read,
 840         .write          = ppp_write,
 841         .poll           = ppp_poll,
 842         .ioctl          = ppp_ioctl,
 843         .open           = ppp_open,
 844         .release        = ppp_release
 845 };
 846
 847 #define PPP_MAJOR       108
 848
 849 /* Called at boot time if ppp is compiled into the kernel,
 850    or at module load time (from init_module) if compiled as a module. */
 851 static int __init ppp_init(void)
 852 {
 853         int err;
 854
 855         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
 856         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
 857         if (!err) {
 858                 ppp_class = class_create(THIS_MODULE, "ppp");
 859                 if (IS_ERR(ppp_class)) {
 860                         err = PTR_ERR(ppp_class);
 861                         goto out_chrdev;
 862                 }
 863                 device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), "ppp");
 864         }
 865
 866 out:
 867         if (err)
 868                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
 869         return err;
 870
 871 out_chrdev:
 872         unregister_chrdev(PPP_MAJOR, "ppp");
 873         goto out;
 874 }
 875
 876 /*
 877  * Network interface unit routines.
 878  */
 879 static int
 880 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 881 {
 882         struct ppp *ppp = (struct ppp *) dev->priv;
 883         int npi, proto;
 884         unsigned char *pp;
 885
 886         npi = ethertype_to_npindex(ntohs(skb->protocol));
 887         if (npi < 0)
 888                 goto outf;
 889
 890         /* Drop, accept or reject the packet */
 891         switch (ppp->npmode[npi]) {
 892         case NPMODE_PASS:
 893                 break;
 894         case NPMODE_QUEUE:
 895                 /* it would be nice to have a way to tell the network
 896                    system to queue this one up for later. */
 897                 goto outf;
 898         case NPMODE_DROP:
 899         case NPMODE_ERROR:
 900                 goto outf;
 901         }
 902
 903         /* Put the 2-byte PPP protocol number on the front,
 904            making sure there is room for the address and control fields. */
 905         if (skb_headroom(skb) < PPP_HDRLEN) {
 906                 struct sk_buff *ns;
 907
 908                 ns = alloc_skb(skb->len + dev->hard_header_len, GFP_ATOMIC);
 909                 if (ns == 0)
 910                         goto outf;
 911                 skb_reserve(ns, dev->hard_header_len);
 912                 skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
 913                 kfree_skb(skb);
 914                 skb = ns;
 915         }
 916         pp = skb_push(skb, 2);
 917         proto = npindex_to_proto[npi];
 918         pp[0] = proto >> 8;
 919         pp[1] = proto;
 920
 921         netif_stop_queue(dev);
 922         skb_queue_tail(&ppp->file.xq, skb);
 923         ppp_xmit_process(ppp);
 924         return 0;
 925
 926  outf:
 927         kfree_skb(skb);
 928         ++ppp->stats.tx_dropped;
 929         return 0;
 930 }
 931
 932 static struct net_device_stats *
 933 ppp_net_stats(struct net_device *dev)
 934 {
 935         struct ppp *ppp = (struct ppp *) dev->priv;
 936
 937         return &ppp->stats;
 938 }
 939
 940 static int
 941 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 942 {
 943         struct ppp *ppp = dev->priv;
 944         int err = -EFAULT;
 945         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
 946         struct ppp_stats stats;
 947         struct ppp_comp_stats cstats;
 948         char *vers;
 949
 950         switch (cmd) {
 951         case SIOCGPPPSTATS:
 952                 ppp_get_stats(ppp, &stats);
 953                 if (copy_to_user(addr, &stats, sizeof(stats)))
 954                         break;
 955                 err = 0;
 956                 break;
 957
 958         case SIOCGPPPCSTATS:
 959                 memset(&cstats, 0, sizeof(cstats));
 960                 if (ppp->xc_state != 0)
 961                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
 962                 if (ppp->rc_state != 0)
 963                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
 964                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
 965                         break;
 966                 err = 0;
 967                 break;
 968
 969         case SIOCGPPPVER:
 970                 vers = PPP_VERSION;
 971                 if (copy_to_user(addr, vers, strlen(vers) + 1))
 972                         break;
 973                 err = 0;
 974                 break;
 975
 976         default:
 977                 err = -EINVAL;
 978         }
 979
 980         return err;
 981 }
 982
 983 static void ppp_setup(struct net_device *dev)
 984 {
 985         dev->hard_header_len = PPP_HDRLEN;
 986         dev->mtu = PPP_MTU;
 987         dev->addr_len = 0;
 988         dev->tx_queue_len = 3;
 989         dev->type = ARPHRD_PPP;
 990         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
 991 }
 992
 993 /*
 994  * Transmit-side routines.
 995  */
 996
 997 /*
 998  * Called to do any work queued up on the transmit side
 999  * that can now be done.
1000  */
1001 static void
1002 ppp_xmit_process(struct ppp *ppp)
1003 {
1004         struct sk_buff *skb;
1005
1006         ppp_xmit_lock(ppp);
1007         if (ppp->dev != 0) {
1008                 ppp_push(ppp);
1009                 while (ppp->xmit_pending == 0
1010                        && (skb = skb_dequeue(&ppp->file.xq)) != 0)
1011                         ppp_send_frame(ppp, skb);
1012                 /* If there's no work left to do, tell the core net
1013                    code that we can accept some more. */
1014                 if (ppp->xmit_pending == 0 && skb_peek(&ppp->file.xq) == 0)
1015                         netif_wake_queue(ppp->dev);
1016         }
1017         ppp_xmit_unlock(ppp);
1018 }
1019
1020 static inline struct sk_buff *
1021 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1022 {
1023         struct sk_buff *new_skb;
1024         int len;
1025         int new_skb_size = ppp->dev->mtu +
1026                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1027         int compressor_skb_size = ppp->dev->mtu +
1028                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1029         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1030         if (!new_skb) {
1031                 if (net_ratelimit())
1032                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1033                 return NULL;
1034         }
1035         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1036                 skb_reserve(new_skb,
1037                             ppp->dev->hard_header_len - PPP_HDRLEN);
1038
1039         /* compressor still expects A/C bytes in hdr */
1040         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1041                                    new_skb->data, skb->len + 2,
1042                                    compressor_skb_size);
1043         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1044                 kfree_skb(skb);
1045                 skb = new_skb;
1046                 skb_put(skb, len);
1047                 skb_pull(skb, 2);       /* pull off A/C bytes */
1048         } else if (len == 0) {
1049                 /* didn't compress, or CCP not up yet */
1050                 kfree_skb(new_skb);
1051                 new_skb = skb;
1052         } else {
1053                 /*
1054                  * (len < 0)
1055                  * MPPE requires that we do not send unencrypted
1056                  * frames.  The compressor will return -1 if we
1057                  * should drop the frame.  We cannot simply test
1058                  * the compress_proto because MPPE and MPPC share
1059                  * the same number.
1060                  */
1061                 if (net_ratelimit())
1062                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1063                 kfree_skb(skb);
1064                 kfree_skb(new_skb);
1065                 new_skb = NULL;
1066         }
1067         return new_skb;
1068 }
1069
1070 /*
1071  * Compress and send a frame.
1072  * The caller should have locked the xmit path,
1073  * and xmit_pending should be 0.
1074  */
1075 static void
1076 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1077 {
1078         int proto = PPP_PROTO(skb);
1079         struct sk_buff *new_skb;
1080         int len;
1081         unsigned char *cp;
1082
1083         if (proto < 0x8000) {
1084 #ifdef CONFIG_PPP_FILTER
1085                 /* check if we should pass this packet */
1086                 /* the filter instructions are constructed assuming
1087                    a four-byte PPP header on each packet */
1088                 *skb_push(skb, 2) = 1;
1089                 if (ppp->pass_filter
1090                     && sk_run_filter(skb, ppp->pass_filter,
1091                                      ppp->pass_len) == 0) {
1092                         if (ppp->debug & 1)
1093                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1094                         kfree_skb(skb);
1095                         return;
1096                 }
1097                 /* if this packet passes the active filter, record the time */
1098                 if (!(ppp->active_filter
1099                       && sk_run_filter(skb, ppp->active_filter,
1100                                        ppp->active_len) == 0))
1101                         ppp->last_xmit = jiffies;
1102                 skb_pull(skb, 2);
1103 #else
1104                 /* for data packets, record the time */
1105                 ppp->last_xmit = jiffies;
1106 #endif /* CONFIG_PPP_FILTER */
1107         }
1108
1109         ++ppp->stats.tx_packets;
1110         ppp->stats.tx_bytes += skb->len - 2;
1111
1112         switch (proto) {
1113         case PPP_IP:
1114                 if (ppp->vj == 0 || (ppp->flags & SC_COMP_TCP) == 0)
1115                         break;
1116                 /* try to do VJ TCP header compression */
1117                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1118                                     GFP_ATOMIC);
1119                 if (new_skb == 0) {
1120                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1121                         goto drop;
1122                 }
1123                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1124                 cp = skb->data + 2;
1125                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1126                                     new_skb->data + 2, &cp,
1127                                     !(ppp->flags & SC_NO_TCP_CCID));
1128                 if (cp == skb->data + 2) {
1129                         /* didn't compress */
1130                         kfree_skb(new_skb);
1131                 } else {
1132                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1133                                 proto = PPP_VJC_COMP;
1134                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1135                         } else {
1136                                 proto = PPP_VJC_UNCOMP;
1137                                 cp[0] = skb->data[2];
1138                         }
1139                         kfree_skb(skb);
1140                         skb = new_skb;
1141                         cp = skb_put(skb, len + 2);
1142                         cp[0] = 0;
1143                         cp[1] = proto;
1144                 }
1145                 break;
1146
1147         case PPP_CCP:
1148                 /* peek at outbound CCP frames */
1149                 ppp_ccp_peek(ppp, skb, 0);
1150                 break;
1151         }
1152
1153         /* try to do packet compression */
1154         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0
1155             && proto != PPP_LCP && proto != PPP_CCP) {
1156                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1157                         if (net_ratelimit())
1158                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1159                         goto drop;
1160                 }
1161                 skb = pad_compress_skb(ppp, skb);
1162                 if (!skb)
1163                         goto drop;
1164         }
1165
1166         /*
1167          * If we are waiting for traffic (demand dialling),
1168          * queue it up for pppd to receive.
1169          */
1170         if (ppp->flags & SC_LOOP_TRAFFIC) {
1171                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1172                         goto drop;
1173                 skb_queue_tail(&ppp->file.rq, skb);
1174                 wake_up_interruptible(&ppp->file.rwait);
1175                 return;
1176         }
1177
1178         ppp->xmit_pending = skb;
1179         ppp_push(ppp);
1180         return;
1181
1182  drop:
1183         if (skb)
1184                 kfree_skb(skb);
1185         ++ppp->stats.tx_errors;
1186 }
1187
1188 /*
1189  * Try to send the frame in xmit_pending.
1190  * The caller should have the xmit path locked.
1191  */
1192 static void
1193 ppp_push(struct ppp *ppp)
1194 {
1195         struct list_head *list;
1196         struct channel *pch;
1197         struct sk_buff *skb = ppp->xmit_pending;
1198
1199         if (skb == 0)
1200                 return;
1201
1202         list = &ppp->channels;
1203         if (list_empty(list)) {
1204                 /* nowhere to send the packet, just drop it */
1205                 ppp->xmit_pending = NULL;
1206                 kfree_skb(skb);
1207                 return;
1208         }
1209
1210         if ((ppp->flags & SC_MULTILINK) == 0) {
1211                 /* not doing multilink: send it down the first channel */
1212                 list = list->next;
1213                 pch = list_entry(list, struct channel, clist);
1214
1215                 spin_lock_bh(&pch->downl);
1216                 if (pch->chan) {
1217                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1218                                 ppp->xmit_pending = NULL;
1219                 } else {
1220                         /* channel got unregistered */
1221                         kfree_skb(skb);
1222                         ppp->xmit_pending = NULL;
1223                 }
1224                 spin_unlock_bh(&pch->downl);
1225                 return;
1226         }
1227
1228 #ifdef CONFIG_PPP_MULTILINK
1229         /* Multilink: fragment the packet over as many links
1230            as can take the packet at the moment. */
1231         if (!ppp_mp_explode(ppp, skb))
1232                 return;
1233 #endif /* CONFIG_PPP_MULTILINK */
1234
1235         ppp->xmit_pending = NULL;
1236         kfree_skb(skb);
1237 }
1238
1239 #ifdef CONFIG_PPP_MULTILINK
1240 /*
1241  * Divide a packet to be transmitted into fragments and
1242  * send them out the individual links.
1243  */
1244 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1245 {
1246         int len, fragsize;
1247         int i, bits, hdrlen, mtu;
1248         int flen;
1249         int navail, nfree;
1250         int nbigger;
1251         unsigned char *p, *q;
1252         struct list_head *list;
1253         struct channel *pch;
1254         struct sk_buff *frag;
1255         struct ppp_channel *chan;
1256
1257         nfree = 0;      /* # channels which have no packet already queued */
1258         navail = 0;     /* total # of usable channels (not deregistered) */
1259         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1260         i = 0;
1261         list_for_each_entry(pch, &ppp->channels, clist) {
1262                 navail += pch->avail = (pch->chan != NULL);
1263                 if (pch->avail) {
1264                         if (skb_queue_empty(&pch->file.xq) ||
1265                             !pch->had_frag) {
1266                                 pch->avail = 2;
1267                                 ++nfree;
1268                         }
1269                         if (!pch->had_frag && i < ppp->nxchan)
1270                                 ppp->nxchan = i;
1271                 }
1272                 ++i;
1273         }
1274
1275         /*
1276          * Don't start sending this packet unless at least half of
1277          * the channels are free.  This gives much better TCP
1278          * performance if we have a lot of channels.
1279          */
1280         if (nfree == 0 || nfree < navail / 2)
1281                 return 0;       /* can't take now, leave it in xmit_pending */
1282
1283         /* Do protocol field compression (XXX this should be optional) */
1284         p = skb->data;
1285         len = skb->len;
1286         if (*p == 0) {
1287                 ++p;
1288                 --len;
1289         }
1290
1291         /*
1292          * Decide on fragment size.
1293          * We create a fragment for each free channel regardless of
1294          * how small they are (i.e. even 0 length) in order to minimize
1295          * the time that it will take to detect when a channel drops
1296          * a fragment.
1297          */
1298         fragsize = len;
1299         if (nfree > 1)
1300                 fragsize = ROUNDUP(fragsize, nfree);
1301         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1302            except if nbigger==0, then they all get fragsize. */
1303         nbigger = len % nfree;
1304
1305         /* skip to the channel after the one we last used
1306            and start at that one */
1307         list = &ppp->channels;
1308         for (i = 0; i < ppp->nxchan; ++i) {
1309                 list = list->next;
1310                 if (list == &ppp->channels) {
1311                         i = 0;
1312                         break;
1313                 }
1314         }
1315
1316         /* create a fragment for each channel */
1317         bits = B;
1318         while (nfree > 0 || len > 0) {
1319                 list = list->next;
1320                 if (list == &ppp->channels) {
1321                         i = 0;
1322                         continue;
1323                 }
1324                 pch = list_entry(list, struct channel, clist);
1325                 ++i;
1326                 if (!pch->avail)
1327                         continue;
1328
1329                 /*
1330                  * Skip this channel if it has a fragment pending already and
1331                  * we haven't given a fragment to all of the free channels.
1332                  */
1333                 if (pch->avail == 1) {
1334                         if (nfree > 0)
1335                                 continue;
1336                 } else {
1337                         --nfree;
1338                         pch->avail = 1;
1339                 }
1340
1341                 /* check the channel's mtu and whether it is still attached. */
1342                 spin_lock_bh(&pch->downl);
1343                 if (pch->chan == NULL) {
1344                         /* can't use this channel, it's being deregistered */
1345                         spin_unlock_bh(&pch->downl);
1346                         pch->avail = 0;
1347                         if (--navail == 0)
1348                                 break;
1349                         continue;
1350                 }
1351
1352                 /*
1353                  * Create a fragment for this channel of
1354                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1355                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1356                  * MTU, so we use mtu = 2 + hdrlen.
1357                  */
1358                 if (fragsize > len)
1359                         fragsize = len;
1360                 flen = fragsize;
1361                 mtu = pch->chan->mtu + 2 - hdrlen;
1362                 if (mtu < 4)
1363                         mtu = 4;
1364                 if (flen > mtu)
1365                         flen = mtu;
1366                 if (flen == len && nfree == 0)
1367                         bits |= E;
1368                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1369                 if (frag == 0)
1370                         goto noskb;
1371                 q = skb_put(frag, flen + hdrlen);
1372
1373                 /* make the MP header */
1374                 q[0] = PPP_MP >> 8;
1375                 q[1] = PPP_MP;
1376                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1377                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1378                         q[3] = ppp->nxseq;
1379                 } else {
1380                         q[2] = bits;
1381                         q[3] = ppp->nxseq >> 16;
1382                         q[4] = ppp->nxseq >> 8;
1383                         q[5] = ppp->nxseq;
1384                 }
1385
1386                 /*
1387                  * Copy the data in.
1388                  * Unfortunately there is a bug in older versions of
1389                  * the Linux PPP multilink reconstruction code where it
1390                  * drops 0-length fragments.  Therefore we make sure the
1391                  * fragment has at least one byte of data.  Any bytes
1392                  * we add in this situation will end up as padding on the
1393                  * end of the reconstructed packet.
1394                  */
1395                 if (flen == 0)
1396                         *skb_put(frag, 1) = 0;
1397                 else
1398                         memcpy(q + hdrlen, p, flen);
1399
1400                 /* try to send it down the channel */
1401                 chan = pch->chan;
1402                 if (!skb_queue_empty(&pch->file.xq) ||
1403                     !chan->ops->start_xmit(chan, frag))
1404                         skb_queue_tail(&pch->file.xq, frag);
1405                 pch->had_frag = 1;
1406                 p += flen;
1407                 len -= flen;
1408                 ++ppp->nxseq;
1409                 bits = 0;
1410                 spin_unlock_bh(&pch->downl);
1411
1412                 if (--nbigger == 0 && fragsize > 0)
1413                         --fragsize;
1414         }
1415         ppp->nxchan = i;
1416
1417         return 1;
1418
1419  noskb:
1420         spin_unlock_bh(&pch->downl);
1421         if (ppp->debug & 1)
1422                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1423         ++ppp->stats.tx_errors;
1424         ++ppp->nxseq;
1425         return 1;       /* abandon the frame */
1426 }
1427 #endif /* CONFIG_PPP_MULTILINK */
1428
1429 /*
1430  * Try to send data out on a channel.
1431  */
1432 static void
1433 ppp_channel_push(struct channel *pch)
1434 {
1435         struct sk_buff *skb;
1436         struct ppp *ppp;
1437
1438         spin_lock_bh(&pch->downl);
1439         if (pch->chan != 0) {
1440                 while (!skb_queue_empty(&pch->file.xq)) {
1441                         skb = skb_dequeue(&pch->file.xq);
1442                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1443                                 /* put the packet back and try again later */
1444                                 skb_queue_head(&pch->file.xq, skb);
1445                                 break;
1446                         }
1447                 }
1448         } else {
1449                 /* channel got deregistered */
1450                 skb_queue_purge(&pch->file.xq);
1451         }
1452         spin_unlock_bh(&pch->downl);
1453         /* see if there is anything from the attached unit to be sent */
1454         if (skb_queue_empty(&pch->file.xq)) {
1455                 read_lock_bh(&pch->upl);
1456                 ppp = pch->ppp;
1457                 if (ppp != 0)
1458                         ppp_xmit_process(ppp);
1459                 read_unlock_bh(&pch->upl);
1460         }
1461 }
1462
1463 /*
1464  * Receive-side routines.
1465  */
1466
1467 /* misuse a few fields of the skb for MP reconstruction */
1468 #define sequence        priority
1469 #define BEbits          cb[0]
1470
1471 static inline void
1472 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1473 {
1474         ppp_recv_lock(ppp);
1475         /* ppp->dev == 0 means interface is closing down */
1476         if (ppp->dev != 0)
1477                 ppp_receive_frame(ppp, skb, pch);
1478         else
1479                 kfree_skb(skb);
1480         ppp_recv_unlock(ppp);
1481 }
1482
1483 void
1484 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1485 {
1486         struct channel *pch = chan->ppp;
1487         int proto;
1488
1489         if (pch == 0 || skb->len == 0) {
1490                 kfree_skb(skb);
1491                 return;
1492         }
1493
1494         proto = PPP_PROTO(skb);
1495         read_lock_bh(&pch->upl);
1496         if (pch->ppp == 0 || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1497                 /* put it on the channel queue */
1498                 skb_queue_tail(&pch->file.rq, skb);
1499                 /* drop old frames if queue too long */
1500                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1501                        && (skb = skb_dequeue(&pch->file.rq)) != 0)
1502                         kfree_skb(skb);
1503                 wake_up_interruptible(&pch->file.rwait);
1504         } else {
1505                 ppp_do_recv(pch->ppp, skb, pch);
1506         }
1507         read_unlock_bh(&pch->upl);
1508 }
1509
1510 /* Put a 0-length skb in the receive queue as an error indication */
1511 void
1512 ppp_input_error(struct ppp_channel *chan, int code)
1513 {
1514         struct channel *pch = chan->ppp;
1515         struct sk_buff *skb;
1516
1517         if (pch == 0)
1518                 return;
1519
1520         read_lock_bh(&pch->upl);
1521         if (pch->ppp != 0) {
1522                 skb = alloc_skb(0, GFP_ATOMIC);
1523                 if (skb != 0) {
1524                         skb->len = 0;           /* probably unnecessary */
1525                         skb->cb[0] = code;
1526                         ppp_do_recv(pch->ppp, skb, pch);
1527                 }
1528         }
1529         read_unlock_bh(&pch->upl);
1530 }
1531
1532 /*
1533  * We come in here to process a received frame.
1534  * The receive side of the ppp unit is locked.
1535  */
1536 static void
1537 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1538 {
1539         if (skb->len >= 2) {
1540 #ifdef CONFIG_PPP_MULTILINK
1541                 /* XXX do channel-level decompression here */
1542                 if (PPP_PROTO(skb) == PPP_MP)
1543                         ppp_receive_mp_frame(ppp, skb, pch);
1544                 else
1545 #endif /* CONFIG_PPP_MULTILINK */
1546                         ppp_receive_nonmp_frame(ppp, skb);
1547                 return;
1548         }
1549
1550         if (skb->len > 0)
1551                 /* note: a 0-length skb is used as an error indication */
1552                 ++ppp->stats.rx_length_errors;
1553
1554         kfree_skb(skb);
1555         ppp_receive_error(ppp);
1556 }
1557
1558 static void
1559 ppp_receive_error(struct ppp *ppp)
1560 {
1561         ++ppp->stats.rx_errors;
1562         if (ppp->vj != 0)
1563                 slhc_toss(ppp->vj);
1564 }
1565
1566 static void
1567 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1568 {
1569         struct sk_buff *ns;
1570         int proto, len, npi;
1571
1572         /*
1573          * Decompress the frame, if compressed.
1574          * Note that some decompressors need to see uncompressed frames
1575          * that come in as well as compressed frames.
1576          */
1577         if (ppp->rc_state != 0 && (ppp->rstate & SC_DECOMP_RUN)
1578             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1579                 skb = ppp_decompress_frame(ppp, skb);
1580
1581         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1582                 goto err;
1583
1584         proto = PPP_PROTO(skb);
1585         switch (proto) {
1586         case PPP_VJC_COMP:
1587                 /* decompress VJ compressed packets */
1588                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1589                         goto err;
1590
1591                 if (skb_tailroom(skb) < 124) {
1592                         /* copy to a new sk_buff with more tailroom */
1593                         ns = dev_alloc_skb(skb->len + 128);
1594                         if (ns == 0) {
1595                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1596                                 goto err;
1597                         }
1598                         skb_reserve(ns, 2);
1599                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1600                         kfree_skb(skb);
1601                         skb = ns;
1602                 }
1603                 else
1604                         skb->ip_summed = CHECKSUM_NONE;
1605
1606                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1607                 if (len <= 0) {
1608                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1609                         goto err;
1610                 }
1611                 len += 2;
1612                 if (len > skb->len)
1613                         skb_put(skb, len - skb->len);
1614                 else if (len < skb->len)
1615                         skb_trim(skb, len);
1616                 proto = PPP_IP;
1617                 break;
1618
1619         case PPP_VJC_UNCOMP:
1620                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1621                         goto err;
1622
1623                 /* Until we fix the decompressor need to make sure
1624                  * data portion is linear.
1625                  */
1626                 if (!pskb_may_pull(skb, skb->len))
1627                         goto err;
1628
1629                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1630                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1631                         goto err;
1632                 }
1633                 proto = PPP_IP;
1634                 break;
1635
1636         case PPP_CCP:
1637                 ppp_ccp_peek(ppp, skb, 1);
1638                 break;
1639         }
1640
1641         ++ppp->stats.rx_packets;
1642         ppp->stats.rx_bytes += skb->len - 2;
1643
1644         npi = proto_to_npindex(proto);
1645         if (npi < 0) {
1646                 /* control or unknown frame - pass it to pppd */
1647                 skb_queue_tail(&ppp->file.rq, skb);
1648                 /* limit queue length by dropping old frames */
1649                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1650                        && (skb = skb_dequeue(&ppp->file.rq)) != 0)
1651                         kfree_skb(skb);
1652                 /* wake up any process polling or blocking on read */
1653                 wake_up_interruptible(&ppp->file.rwait);
1654
1655         } else {
1656                 /* network protocol frame - give it to the kernel */
1657
1658 #ifdef CONFIG_PPP_FILTER
1659                 /* check if the packet passes the pass and active filters */
1660                 /* the filter instructions are constructed assuming
1661                    a four-byte PPP header on each packet */
1662                 *skb_push(skb, 2) = 0;
1663                 if (ppp->pass_filter
1664                     && sk_run_filter(skb, ppp->pass_filter,
1665                                      ppp->pass_len) == 0) {
1666                         if (ppp->debug & 1)
1667                                 printk(KERN_DEBUG "PPP: inbound frame not passed\n");
1668                         kfree_skb(skb);
1669                         return;
1670                 }
1671                 if (!(ppp->active_filter
1672                       && sk_run_filter(skb, ppp->active_filter,
1673                                        ppp->active_len) == 0))
1674                         ppp->last_recv = jiffies;
1675                 skb_pull(skb, 2);
1676 #else
1677                 ppp->last_recv = jiffies;
1678 #endif /* CONFIG_PPP_FILTER */
1679
1680                 if ((ppp->dev->flags & IFF_UP) == 0
1681                     || ppp->npmode[npi] != NPMODE_PASS) {
1682                         kfree_skb(skb);
1683                 } else {
1684                         /* chop off protocol */
1685                         skb_pull_rcsum(skb, 2);
1686                         skb->dev = ppp->dev;
1687                         skb->protocol = htons(npindex_to_ethertype[npi]);
1688                         skb->mac.raw = skb->data;
1689                         netif_rx(skb);
1690                         ppp->dev->last_rx = jiffies;
1691                 }
1692         }
1693         return;
1694
1695  err:
1696         kfree_skb(skb);
1697         ppp_receive_error(ppp);
1698 }
1699
1700 static struct sk_buff *
1701 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1702 {
1703         int proto = PPP_PROTO(skb);
1704         struct sk_buff *ns;
1705         int len;
1706
1707         /* Until we fix all the decompressor's need to make sure
1708          * data portion is linear.
1709          */
1710         if (!pskb_may_pull(skb, skb->len))
1711                 goto err;
1712
1713         if (proto == PPP_COMP) {
1714                 ns = dev_alloc_skb(ppp->mru + PPP_HDRLEN);
1715                 if (ns == 0) {
1716                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1717                         goto err;
1718                 }
1719                 /* the decompressor still expects the A/C bytes in the hdr */
1720                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1721                                 skb->len + 2, ns->data, ppp->mru + PPP_HDRLEN);
1722                 if (len < 0) {
1723                         /* Pass the compressed frame to pppd as an
1724                            error indication. */
1725                         if (len == DECOMP_FATALERROR)
1726                                 ppp->rstate |= SC_DC_FERROR;
1727                         kfree_skb(ns);
1728                         goto err;
1729                 }
1730
1731                 kfree_skb(skb);
1732                 skb = ns;
1733                 skb_put(skb, len);
1734                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1735
1736         } else {
1737                 /* Uncompressed frame - pass to decompressor so it
1738                    can update its dictionary if necessary. */
1739                 if (ppp->rcomp->incomp)
1740                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1741                                            skb->len + 2);
1742         }
1743
1744         return skb;
1745
1746  err:
1747         ppp->rstate |= SC_DC_ERROR;
1748         ppp_receive_error(ppp);
1749         return skb;
1750 }
1751
1752 #ifdef CONFIG_PPP_MULTILINK
1753 /*
1754  * Receive a multilink frame.
1755  * We put it on the reconstruction queue and then pull off
1756  * as many completed frames as we can.
1757  */
1758 static void
1759 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1760 {
1761         u32 mask, seq;
1762         struct channel *ch;
1763         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1764
1765         if (!pskb_may_pull(skb, mphdrlen) || ppp->mrru == 0)
1766                 goto err;               /* no good, throw it away */
1767
1768         /* Decode sequence number and begin/end bits */
1769         if (ppp->flags & SC_MP_SHORTSEQ) {
1770                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1771                 mask = 0xfff;
1772         } else {
1773                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1774                 mask = 0xffffff;
1775         }
1776         skb->BEbits = skb->data[2];
1777         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1778
1779         /*
1780          * Do protocol ID decompression on the first fragment of each packet.
1781          */
1782         if ((skb->BEbits & B) && (skb->data[0] & 1))
1783                 *skb_push(skb, 1) = 0;
1784
1785         /*
1786          * Expand sequence number to 32 bits, making it as close
1787          * as possible to ppp->minseq.
1788          */
1789         seq |= ppp->minseq & ~mask;
1790         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1791                 seq += mask + 1;
1792         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1793                 seq -= mask + 1;        /* should never happen */
1794         skb->sequence = seq;
1795         pch->lastseq = seq;
1796
1797         /*
1798          * If this packet comes before the next one we were expecting,
1799          * drop it.
1800          */
1801         if (seq_before(seq, ppp->nextseq)) {
1802                 kfree_skb(skb);
1803                 ++ppp->stats.rx_dropped;
1804                 ppp_receive_error(ppp);
1805                 return;
1806         }
1807
1808         /*
1809          * Reevaluate minseq, the minimum over all channels of the
1810          * last sequence number received on each channel.  Because of
1811          * the increasing sequence number rule, we know that any fragment
1812          * before `minseq' which hasn't arrived is never going to arrive.
1813          * The list of channels can't change because we have the receive
1814          * side of the ppp unit locked.
1815          */
1816         list_for_each_entry(ch, &ppp->channels, clist) {
1817                 if (seq_before(ch->lastseq, seq))
1818                         seq = ch->lastseq;
1819         }
1820         if (seq_before(ppp->minseq, seq))
1821                 ppp->minseq = seq;
1822
1823         /* Put the fragment on the reconstruction queue */
1824         ppp_mp_insert(ppp, skb);
1825
1826         /* If the queue is getting long, don't wait any longer for packets
1827            before the start of the queue. */
1828         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN
1829             && seq_before(ppp->minseq, ppp->mrq.next->sequence))
1830                 ppp->minseq = ppp->mrq.next->sequence;
1831
1832         /* Pull completed packets off the queue and receive them. */
1833         while ((skb = ppp_mp_reconstruct(ppp)) != 0)
1834                 ppp_receive_nonmp_frame(ppp, skb);
1835
1836         return;
1837
1838  err:
1839         kfree_skb(skb);
1840         ppp_receive_error(ppp);
1841 }
1842
1843 /*
1844  * Insert a fragment on the MP reconstruction queue.
1845  * The queue is ordered by increasing sequence number.
1846  */
1847 static void
1848 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1849 {
1850         struct sk_buff *p;
1851         struct sk_buff_head *list = &ppp->mrq;
1852         u32 seq = skb->sequence;
1853
1854         /* N.B. we don't need to lock the list lock because we have the
1855            ppp unit receive-side lock. */
1856         for (p = list->next; p != (struct sk_buff *)list; p = p->next)
1857                 if (seq_before(seq, p->sequence))
1858                         break;
1859         __skb_insert(skb, p->prev, p, list);
1860 }
1861
1862 /*
1863  * Reconstruct a packet from the MP fragment queue.
1864  * We go through increasing sequence numbers until we find a
1865  * complete packet, or we get to the sequence number for a fragment
1866  * which hasn't arrived but might still do so.
1867  */
1868 struct sk_buff *
1869 ppp_mp_reconstruct(struct ppp *ppp)
1870 {
1871         u32 seq = ppp->nextseq;
1872         u32 minseq = ppp->minseq;
1873         struct sk_buff_head *list = &ppp->mrq;
1874         struct sk_buff *p, *next;
1875         struct sk_buff *head, *tail;
1876         struct sk_buff *skb = NULL;
1877         int lost = 0, len = 0;
1878
1879         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1880                 return NULL;
1881         head = list->next;
1882         tail = NULL;
1883         for (p = head; p != (struct sk_buff *) list; p = next) {
1884                 next = p->next;
1885                 if (seq_before(p->sequence, seq)) {
1886                         /* this can't happen, anyway ignore the skb */
1887                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1888                                p->sequence, seq);
1889                         head = next;
1890                         continue;
1891                 }
1892                 if (p->sequence != seq) {
1893                         /* Fragment `seq' is missing.  If it is after
1894                            minseq, it might arrive later, so stop here. */
1895                         if (seq_after(seq, minseq))
1896                                 break;
1897                         /* Fragment `seq' is lost, keep going. */
1898                         lost = 1;
1899                         seq = seq_before(minseq, p->sequence)?
1900                                 minseq + 1: p->sequence;
1901                         next = p;
1902                         continue;
1903                 }
1904
1905                 /*
1906                  * At this point we know that all the fragments from
1907                  * ppp->nextseq to seq are either present or lost.
1908                  * Also, there are no complete packets in the queue
1909                  * that have no missing fragments and end before this
1910                  * fragment.
1911                  */
1912
1913                 /* B bit set indicates this fragment starts a packet */
1914                 if (p->BEbits & B) {
1915                         head = p;
1916                         lost = 0;
1917                         len = 0;
1918                 }
1919
1920                 len += p->len;
1921
1922                 /* Got a complete packet yet? */
1923                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1924                         if (len > ppp->mrru + 2) {
1925                                 ++ppp->stats.rx_length_errors;
1926                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1927                                        " is too long (%d)\n", len);
1928                         } else if (p == head) {
1929                                 /* fragment is complete packet - reuse skb */
1930                                 tail = p;
1931                                 skb = skb_get(p);
1932                                 break;
1933                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1934                                 ++ppp->stats.rx_missed_errors;
1935                                 printk(KERN_DEBUG "PPP: no memory for "
1936                                        "reconstructed packet");
1937                         } else {
1938                                 tail = p;
1939                                 break;
1940                         }
1941                         ppp->nextseq = seq + 1;
1942                 }
1943
1944                 /*
1945                  * If this is the ending fragment of a packet,
1946                  * and we haven't found a complete valid packet yet,
1947                  * we can discard up to and including this fragment.
1948                  */
1949                 if (p->BEbits & E)
1950                         head = next;
1951
1952                 ++seq;
1953         }
1954
1955         /* If we have a complete packet, copy it all into one skb. */
1956         if (tail != NULL) {
1957                 /* If we have discarded any fragments,
1958                    signal a receive error. */
1959                 if (head->sequence != ppp->nextseq) {
1960                         if (ppp->debug & 1)
1961                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1962                                        ppp->nextseq, head->sequence-1);
1963                         ++ppp->stats.rx_dropped;
1964                         ppp_receive_error(ppp);
1965                 }
1966
1967                 if (head != tail)
1968                         /* copy to a single skb */
1969                         for (p = head; p != tail->next; p = p->next)
1970                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1971                 ppp->nextseq = tail->sequence + 1;
1972                 head = tail->next;
1973         }
1974
1975         /* Discard all the skbuffs that we have copied the data out of
1976            or that we can't use. */
1977         while ((p = list->next) != head) {
1978                 __skb_unlink(p, list);
1979                 kfree_skb(p);
1980         }
1981
1982         return skb;
1983 }
1984 #endif /* CONFIG_PPP_MULTILINK */
1985
1986 /*
1987  * Channel interface.
1988  */
1989
1990 /*
1991  * Create a new, unattached ppp channel.
1992  */
1993 int
1994 ppp_register_channel(struct ppp_channel *chan)
1995 {
1996         struct channel *pch;
1997
1998         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
1999         if (pch == 0)
2000                 return -ENOMEM;
2001         pch->ppp = NULL;
2002         pch->chan = chan;
2003         chan->ppp = pch;
2004         init_ppp_file(&pch->file, CHANNEL);
2005         pch->file.hdrlen = chan->hdrlen;
2006 #ifdef CONFIG_PPP_MULTILINK
2007         pch->lastseq = -1;
2008 #endif /* CONFIG_PPP_MULTILINK */
2009         init_rwsem(&pch->chan_sem);
2010         spin_lock_init(&pch->downl);
2011         rwlock_init(&pch->upl);
2012         spin_lock_bh(&all_channels_lock);
2013         pch->file.index = ++last_channel_index;
2014         list_add(&pch->list, &new_channels);
2015         atomic_inc(&channel_count);
2016         spin_unlock_bh(&all_channels_lock);
2017         return 0;
2018 }
2019
2020 /*
2021  * Return the index of a channel.
2022  */
2023 int ppp_channel_index(struct ppp_channel *chan)
2024 {
2025         struct channel *pch = chan->ppp;
2026
2027         if (pch != 0)
2028                 return pch->file.index;
2029         return -1;
2030 }
2031
2032 /*
2033  * Return the PPP unit number to which a channel is connected.
2034  */
2035 int ppp_unit_number(struct ppp_channel *chan)
2036 {
2037         struct channel *pch = chan->ppp;
2038         int unit = -1;
2039
2040         if (pch != 0) {
2041                 read_lock_bh(&pch->upl);
2042                 if (pch->ppp != 0)
2043                         unit = pch->ppp->file.index;
2044                 read_unlock_bh(&pch->upl);
2045         }
2046         return unit;
2047 }
2048
2049 /*
2050  * Disconnect a channel from the generic layer.
2051  * This must be called in process context.
2052  */
2053 void
2054 ppp_unregister_channel(struct ppp_channel *chan)
2055 {
2056         struct channel *pch = chan->ppp;
2057
2058         if (pch == 0)
2059                 return;         /* should never happen */
2060         chan->ppp = NULL;
2061
2062         /*
2063          * This ensures that we have returned from any calls into the
2064          * the channel's start_xmit or ioctl routine before we proceed.
2065          */
2066         down_write(&pch->chan_sem);
2067         spin_lock_bh(&pch->downl);
2068         pch->chan = NULL;
2069         spin_unlock_bh(&pch->downl);
2070         up_write(&pch->chan_sem);
2071         ppp_disconnect_channel(pch);
2072         spin_lock_bh(&all_channels_lock);
2073         list_del(&pch->list);
2074         spin_unlock_bh(&all_channels_lock);
2075         pch->file.dead = 1;
2076         wake_up_interruptible(&pch->file.rwait);
2077         if (atomic_dec_and_test(&pch->file.refcnt))
2078                 ppp_destroy_channel(pch);
2079 }
2080
2081 /*
2082  * Callback from a channel when it can accept more to transmit.
2083  * This should be called at BH/softirq level, not interrupt level.
2084  */
2085 void
2086 ppp_output_wakeup(struct ppp_channel *chan)
2087 {
2088         struct channel *pch = chan->ppp;
2089
2090         if (pch == 0)
2091                 return;
2092         ppp_channel_push(pch);
2093 }
2094
2095 /*
2096  * Compression control.
2097  */
2098
2099 /* Process the PPPIOCSCOMPRESS ioctl. */
2100 static int
2101 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2102 {
2103         int err;
2104         struct compressor *cp, *ocomp;
2105         struct ppp_option_data data;
2106         void *state, *ostate;
2107         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2108
2109         err = -EFAULT;
2110         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2111             || (data.length <= CCP_MAX_OPTION_LENGTH
2112                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2113                 goto out;
2114         err = -EINVAL;
2115         if (data.length > CCP_MAX_OPTION_LENGTH
2116             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2117                 goto out;
2118
2119         cp = find_compressor(ccp_option[0]);
2120 #ifdef CONFIG_KMOD
2121         if (cp == 0) {
2122                 request_module("ppp-compress-%d", ccp_option[0]);
2123                 cp = find_compressor(ccp_option[0]);
2124         }
2125 #endif /* CONFIG_KMOD */
2126         if (cp == 0)
2127                 goto out;
2128
2129         err = -ENOBUFS;
2130         if (data.transmit) {
2131                 state = cp->comp_alloc(ccp_option, data.length);
2132                 if (state != 0) {
2133                         ppp_xmit_lock(ppp);
2134                         ppp->xstate &= ~SC_COMP_RUN;
2135                         ocomp = ppp->xcomp;
2136                         ostate = ppp->xc_state;
2137                         ppp->xcomp = cp;
2138                         ppp->xc_state = state;
2139                         ppp_xmit_unlock(ppp);
2140                         if (ostate != 0) {
2141                                 ocomp->comp_free(ostate);
2142                                 module_put(ocomp->owner);
2143                         }
2144                         err = 0;
2145                 } else
2146                         module_put(cp->owner);
2147
2148         } else {
2149                 state = cp->decomp_alloc(ccp_option, data.length);
2150                 if (state != 0) {
2151                         ppp_recv_lock(ppp);
2152                         ppp->rstate &= ~SC_DECOMP_RUN;
2153                         ocomp = ppp->rcomp;
2154                         ostate = ppp->rc_state;
2155                         ppp->rcomp = cp;
2156                         ppp->rc_state = state;
2157                         ppp_recv_unlock(ppp);
2158                         if (ostate != 0) {
2159                                 ocomp->decomp_free(ostate);
2160                                 module_put(ocomp->owner);
2161                         }
2162                         err = 0;
2163                 } else
2164                         module_put(cp->owner);
2165         }
2166
2167  out:
2168         return err;
2169 }
2170
2171 /*
2172  * Look at a CCP packet and update our state accordingly.
2173  * We assume the caller has the xmit or recv path locked.
2174  */
2175 static void
2176 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2177 {
2178         unsigned char *dp;
2179         int len;
2180
2181         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2182                 return; /* no header */
2183         dp = skb->data + 2;
2184
2185         switch (CCP_CODE(dp)) {
2186         case CCP_CONFREQ:
2187
2188                 /* A ConfReq starts negotiation of compression
2189                  * in one direction of transmission,
2190                  * and hence brings it down...but which way?
2191                  *
2192                  * Remember:
2193                  * A ConfReq indicates what the sender would like to receive
2194                  */
2195                 if(inbound)
2196                         /* He is proposing what I should send */
2197                         ppp->xstate &= ~SC_COMP_RUN;
2198                 else
2199                         /* I am proposing to what he should send */
2200                         ppp->rstate &= ~SC_DECOMP_RUN;
2201
2202                 break;
2203
2204         case CCP_TERMREQ:
2205         case CCP_TERMACK:
2206                 /*
2207                  * CCP is going down, both directions of transmission
2208                  */
2209                 ppp->rstate &= ~SC_DECOMP_RUN;
2210                 ppp->xstate &= ~SC_COMP_RUN;
2211                 break;
2212
2213         case CCP_CONFACK:
2214                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2215                         break;
2216                 len = CCP_LENGTH(dp);
2217                 if (!pskb_may_pull(skb, len + 2))
2218                         return;         /* too short */
2219                 dp += CCP_HDRLEN;
2220                 len -= CCP_HDRLEN;
2221                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2222                         break;
2223                 if (inbound) {
2224                         /* we will start receiving compressed packets */
2225                         if (ppp->rc_state == 0)
2226                                 break;
2227                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2228                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2229                                 ppp->rstate |= SC_DECOMP_RUN;
2230                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2231                         }
2232                 } else {
2233                         /* we will soon start sending compressed packets */
2234                         if (ppp->xc_state == 0)
2235                                 break;
2236                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2237                                         ppp->file.index, 0, ppp->debug))
2238                                 ppp->xstate |= SC_COMP_RUN;
2239                 }
2240                 break;
2241
2242         case CCP_RESETACK:
2243                 /* reset the [de]compressor */
2244                 if ((ppp->flags & SC_CCP_UP) == 0)
2245                         break;
2246                 if (inbound) {
2247                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2248                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2249                                 ppp->rstate &= ~SC_DC_ERROR;
2250                         }
2251                 } else {
2252                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2253                                 ppp->xcomp->comp_reset(ppp->xc_state);
2254                 }
2255                 break;
2256         }
2257 }
2258
2259 /* Free up compression resources. */
2260 static void
2261 ppp_ccp_closed(struct ppp *ppp)
2262 {
2263         void *xstate, *rstate;
2264         struct compressor *xcomp, *rcomp;
2265
2266         ppp_lock(ppp);
2267         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2268         ppp->xstate = 0;
2269         xcomp = ppp->xcomp;
2270         xstate = ppp->xc_state;
2271         ppp->xc_state = NULL;
2272         ppp->rstate = 0;
2273         rcomp = ppp->rcomp;
2274         rstate = ppp->rc_state;
2275         ppp->rc_state = NULL;
2276         ppp_unlock(ppp);
2277
2278         if (xstate) {
2279                 xcomp->comp_free(xstate);
2280                 module_put(xcomp->owner);
2281         }
2282         if (rstate) {
2283                 rcomp->decomp_free(rstate);
2284                 module_put(rcomp->owner);
2285         }
2286 }
2287
2288 /* List of compressors. */
2289 static LIST_HEAD(compressor_list);
2290 static DEFINE_SPINLOCK(compressor_list_lock);
2291
2292 struct compressor_entry {
2293         struct list_head list;
2294         struct compressor *comp;
2295 };
2296
2297 static struct compressor_entry *
2298 find_comp_entry(int proto)
2299 {
2300         struct compressor_entry *ce;
2301
2302         list_for_each_entry(ce, &compressor_list, list) {
2303                 if (ce->comp->compress_proto == proto)
2304                         return ce;
2305         }
2306         return NULL;
2307 }
2308
2309 /* Register a compressor */
2310 int
2311 ppp_register_compressor(struct compressor *cp)
2312 {
2313         struct compressor_entry *ce;
2314         int ret;
2315         spin_lock(&compressor_list_lock);
2316         ret = -EEXIST;
2317         if (find_comp_entry(cp->compress_proto) != 0)
2318                 goto out;
2319         ret = -ENOMEM;
2320         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2321         if (ce == 0)
2322                 goto out;
2323         ret = 0;
2324         ce->comp = cp;
2325         list_add(&ce->list, &compressor_list);
2326  out:
2327         spin_unlock(&compressor_list_lock);
2328         return ret;
2329 }
2330
2331 /* Unregister a compressor */
2332 void
2333 ppp_unregister_compressor(struct compressor *cp)
2334 {
2335         struct compressor_entry *ce;
2336
2337         spin_lock(&compressor_list_lock);
2338         ce = find_comp_entry(cp->compress_proto);
2339         if (ce != 0 && ce->comp == cp) {
2340                 list_del(&ce->list);
2341                 kfree(ce);
2342         }
2343         spin_unlock(&compressor_list_lock);
2344 }
2345
2346 /* Find a compressor. */
2347 static struct compressor *
2348 find_compressor(int type)
2349 {
2350         struct compressor_entry *ce;
2351         struct compressor *cp = NULL;
2352
2353         spin_lock(&compressor_list_lock);
2354         ce = find_comp_entry(type);
2355         if (ce != 0) {
2356                 cp = ce->comp;
2357                 if (!try_module_get(cp->owner))
2358                         cp = NULL;
2359         }
2360         spin_unlock(&compressor_list_lock);
2361         return cp;
2362 }
2363
2364 /*
2365  * Miscelleneous stuff.
2366  */
2367
2368 static void
2369 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2370 {
2371         struct slcompress *vj = ppp->vj;
2372
2373         memset(st, 0, sizeof(*st));
2374         st->p.ppp_ipackets = ppp->stats.rx_packets;
2375         st->p.ppp_ierrors = ppp->stats.rx_errors;
2376         st->p.ppp_ibytes = ppp->stats.rx_bytes;
2377         st->p.ppp_opackets = ppp->stats.tx_packets;
2378         st->p.ppp_oerrors = ppp->stats.tx_errors;
2379         st->p.ppp_obytes = ppp->stats.tx_bytes;
2380         if (vj == 0)
2381                 return;
2382         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2383         st->vj.vjs_compressed = vj->sls_o_compressed;
2384         st->vj.vjs_searches = vj->sls_o_searches;
2385         st->vj.vjs_misses = vj->sls_o_misses;
2386         st->vj.vjs_errorin = vj->sls_i_error;
2387         st->vj.vjs_tossed = vj->sls_i_tossed;
2388         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2389         st->vj.vjs_compressedin = vj->sls_i_compressed;
2390 }
2391
2392 /*
2393  * Stuff for handling the lists of ppp units and channels
2394  * and for initialization.
2395  */
2396
2397 /*
2398  * Create a new ppp interface unit.  Fails if it can't allocate memory
2399  * or if there is already a unit with the requested number.
2400  * unit == -1 means allocate a new number.
2401  */
2402 static struct ppp *
2403 ppp_create_interface(int unit, int *retp)
2404 {
2405         struct ppp *ppp;
2406         struct net_device *dev = NULL;
2407         int ret = -ENOMEM;
2408         int i;
2409
2410         ppp = kzalloc(sizeof(struct ppp), GFP_KERNEL);
2411         if (!ppp)
2412                 goto out;
2413         dev = alloc_netdev(0, "", ppp_setup);
2414         if (!dev)
2415                 goto out1;
2416
2417         ppp->mru = PPP_MRU;
2418         init_ppp_file(&ppp->file, INTERFACE);
2419         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2420         for (i = 0; i < NUM_NP; ++i)
2421                 ppp->npmode[i] = NPMODE_PASS;
2422         INIT_LIST_HEAD(&ppp->channels);
2423         spin_lock_init(&ppp->rlock);
2424         spin_lock_init(&ppp->wlock);
2425 #ifdef CONFIG_PPP_MULTILINK
2426         ppp->minseq = -1;
2427         skb_queue_head_init(&ppp->mrq);
2428 #endif /* CONFIG_PPP_MULTILINK */
2429         ppp->dev = dev;
2430         dev->priv = ppp;
2431
2432         dev->hard_start_xmit = ppp_start_xmit;
2433         dev->get_stats = ppp_net_stats;
2434         dev->do_ioctl = ppp_net_ioctl;
2435
2436         ret = -EEXIST;
2437         mutex_lock(&all_ppp_mutex);
2438         if (unit < 0)
2439                 unit = cardmap_find_first_free(all_ppp_units);
2440         else if (cardmap_get(all_ppp_units, unit) != NULL)
2441                 goto out2;      /* unit already exists */
2442
2443         /* Initialize the new ppp unit */
2444         ppp->file.index = unit;
2445         sprintf(dev->name, "ppp%d", unit);
2446
2447         ret = register_netdev(dev);
2448         if (ret != 0) {
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         ret = cardmap_set(&all_ppp_units, unit, ppp);
2456         if (ret != 0)
2457                 goto out3;
2458
2459         mutex_unlock(&all_ppp_mutex);
2460         *retp = 0;
2461         return ppp;
2462
2463 out3:
2464         atomic_dec(&ppp_unit_count);
2465 out2:
2466         mutex_unlock(&all_ppp_mutex);
2467         free_netdev(dev);
2468 out1:
2469         kfree(ppp);
2470 out:
2471         *retp = ret;
2472         return NULL;
2473 }
2474
2475 /*
2476  * Initialize a ppp_file structure.
2477  */
2478 static void
2479 init_ppp_file(struct ppp_file *pf, int kind)
2480 {
2481         pf->kind = kind;
2482         skb_queue_head_init(&pf->xq);
2483         skb_queue_head_init(&pf->rq);
2484         atomic_set(&pf->refcnt, 1);
2485         init_waitqueue_head(&pf->rwait);
2486 }
2487
2488 /*
2489  * Take down a ppp interface unit - called when the owning file
2490  * (the one that created the unit) is closed or detached.
2491  */
2492 static void ppp_shutdown_interface(struct ppp *ppp)
2493 {
2494         struct net_device *dev;
2495
2496         mutex_lock(&all_ppp_mutex);
2497         ppp_lock(ppp);
2498         dev = ppp->dev;
2499         ppp->dev = NULL;
2500         ppp_unlock(ppp);
2501         /* This will call dev_close() for us. */
2502         if (dev) {
2503                 unregister_netdev(dev);
2504                 free_netdev(dev);
2505         }
2506         cardmap_set(&all_ppp_units, ppp->file.index, NULL);
2507         ppp->file.dead = 1;
2508         ppp->owner = NULL;
2509         wake_up_interruptible(&ppp->file.rwait);
2510         mutex_unlock(&all_ppp_mutex);
2511 }
2512
2513 /*
2514  * Free the memory used by a ppp unit.  This is only called once
2515  * there are no channels connected to the unit and no file structs
2516  * that reference the unit.
2517  */
2518 static void ppp_destroy_interface(struct ppp *ppp)
2519 {
2520         atomic_dec(&ppp_unit_count);
2521
2522         if (!ppp->file.dead || ppp->n_channels) {
2523                 /* "can't happen" */
2524                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2525                        "n_channels=%d !\n", ppp, ppp->file.dead,
2526                        ppp->n_channels);
2527                 return;
2528         }
2529
2530         ppp_ccp_closed(ppp);
2531         if (ppp->vj) {
2532                 slhc_free(ppp->vj);
2533                 ppp->vj = NULL;
2534         }
2535         skb_queue_purge(&ppp->file.xq);
2536         skb_queue_purge(&ppp->file.rq);
2537 #ifdef CONFIG_PPP_MULTILINK
2538         skb_queue_purge(&ppp->mrq);
2539 #endif /* CONFIG_PPP_MULTILINK */
2540 #ifdef CONFIG_PPP_FILTER
2541         kfree(ppp->pass_filter);
2542         ppp->pass_filter = NULL;
2543         kfree(ppp->active_filter);
2544         ppp->active_filter = NULL;
2545 #endif /* CONFIG_PPP_FILTER */
2546
2547         if (ppp->xmit_pending)
2548                 kfree_skb(ppp->xmit_pending);
2549
2550         kfree(ppp);
2551 }
2552
2553 /*
2554  * Locate an existing ppp unit.
2555  * The caller should have locked the all_ppp_mutex.
2556  */
2557 static struct ppp *
2558 ppp_find_unit(int unit)
2559 {
2560         return cardmap_get(all_ppp_units, unit);
2561 }
2562
2563 /*
2564  * Locate an existing ppp channel.
2565  * The caller should have locked the all_channels_lock.
2566  * First we look in the new_channels list, then in the
2567  * all_channels list.  If found in the new_channels list,
2568  * we move it to the all_channels list.  This is for speed
2569  * when we have a lot of channels in use.
2570  */
2571 static struct channel *
2572 ppp_find_channel(int unit)
2573 {
2574         struct channel *pch;
2575
2576         list_for_each_entry(pch, &new_channels, list) {
2577                 if (pch->file.index == unit) {
2578                         list_move(&pch->list, &all_channels);
2579                         return pch;
2580                 }
2581         }
2582         list_for_each_entry(pch, &all_channels, list) {
2583                 if (pch->file.index == unit)
2584                         return pch;
2585         }
2586         return NULL;
2587 }
2588
2589 /*
2590  * Connect a PPP channel to a PPP interface unit.
2591  */
2592 static int
2593 ppp_connect_channel(struct channel *pch, int unit)
2594 {
2595         struct ppp *ppp;
2596         int ret = -ENXIO;
2597         int hdrlen;
2598
2599         mutex_lock(&all_ppp_mutex);
2600         ppp = ppp_find_unit(unit);
2601         if (ppp == 0)
2602                 goto out;
2603         write_lock_bh(&pch->upl);
2604         ret = -EINVAL;
2605         if (pch->ppp != 0)
2606                 goto outl;
2607
2608         ppp_lock(ppp);
2609         if (pch->file.hdrlen > ppp->file.hdrlen)
2610                 ppp->file.hdrlen = pch->file.hdrlen;
2611         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2612         if (ppp->dev && hdrlen > ppp->dev->hard_header_len)
2613                 ppp->dev->hard_header_len = hdrlen;
2614         list_add_tail(&pch->clist, &ppp->channels);
2615         ++ppp->n_channels;
2616         pch->ppp = ppp;
2617         atomic_inc(&ppp->file.refcnt);
2618         ppp_unlock(ppp);
2619         ret = 0;
2620
2621  outl:
2622         write_unlock_bh(&pch->upl);
2623  out:
2624         mutex_unlock(&all_ppp_mutex);
2625         return ret;
2626 }
2627
2628 /*
2629  * Disconnect a channel from its ppp unit.
2630  */
2631 static int
2632 ppp_disconnect_channel(struct channel *pch)
2633 {
2634         struct ppp *ppp;
2635         int err = -EINVAL;
2636
2637         write_lock_bh(&pch->upl);
2638         ppp = pch->ppp;
2639         pch->ppp = NULL;
2640         write_unlock_bh(&pch->upl);
2641         if (ppp != 0) {
2642                 /* remove it from the ppp unit's list */
2643                 ppp_lock(ppp);
2644                 list_del(&pch->clist);
2645                 if (--ppp->n_channels == 0)
2646                         wake_up_interruptible(&ppp->file.rwait);
2647                 ppp_unlock(ppp);
2648                 if (atomic_dec_and_test(&ppp->file.refcnt))
2649                         ppp_destroy_interface(ppp);
2650                 err = 0;
2651         }
2652         return err;
2653 }
2654
2655 /*
2656  * Free up the resources used by a ppp channel.
2657  */
2658 static void ppp_destroy_channel(struct channel *pch)
2659 {
2660         atomic_dec(&channel_count);
2661
2662         if (!pch->file.dead) {
2663                 /* "can't happen" */
2664                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2665                        pch);
2666                 return;
2667         }
2668         skb_queue_purge(&pch->file.xq);
2669         skb_queue_purge(&pch->file.rq);
2670         kfree(pch);
2671 }
2672
2673 static void __exit ppp_cleanup(void)
2674 {
2675         /* should never happen */
2676         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2677                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2678         cardmap_destroy(&all_ppp_units);
2679         if (unregister_chrdev(PPP_MAJOR, "ppp") != 0)
2680                 printk(KERN_ERR "PPP: failed to unregister PPP device\n");
2681         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2682         class_destroy(ppp_class);
2683 }
2684
2685 /*
2686  * Cardmap implementation.
2687  */
2688 static void *cardmap_get(struct cardmap *map, unsigned int nr)
2689 {
2690         struct cardmap *p;
2691         int i;
2692
2693         for (p = map; p != NULL; ) {
2694                 if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
2695                         return NULL;
2696                 if (p->shift == 0)
2697                         return p->ptr[i];
2698                 nr &= ~(CARDMAP_MASK << p->shift);
2699                 p = p->ptr[i];
2700         }
2701         return NULL;
2702 }
2703
2704 static int cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
2705 {
2706         struct cardmap *p;
2707         int i;
2708
2709         p = *pmap;
2710         if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
2711                 do {
2712                         /* need a new top level */
2713                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2714                         if (!np)
2715                                 goto enomem;
2716                         np->ptr[0] = p;
2717                         if (p != NULL) {
2718                                 np->shift = p->shift + CARDMAP_ORDER;
2719                                 p->parent = np;
2720                         } else
2721                                 np->shift = 0;
2722                         p = np;
2723                 } while ((nr >> p->shift) >= CARDMAP_WIDTH);
2724                 *pmap = p;
2725         }
2726         while (p->shift > 0) {
2727                 i = (nr >> p->shift) & CARDMAP_MASK;
2728                 if (p->ptr[i] == NULL) {
2729                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2730                         if (!np)
2731                                 goto enomem;
2732                         np->shift = p->shift - CARDMAP_ORDER;
2733                         np->parent = p;
2734                         p->ptr[i] = np;
2735                 }
2736                 if (ptr == NULL)
2737                         clear_bit(i, &p->inuse);
2738                 p = p->ptr[i];
2739         }
2740         i = nr & CARDMAP_MASK;
2741         p->ptr[i] = ptr;
2742         if (ptr != NULL)
2743                 set_bit(i, &p->inuse);
2744         else
2745                 clear_bit(i, &p->inuse);
2746         return 0;
2747  enomem:
2748         return -ENOMEM;
2749 }
2750
2751 static unsigned int cardmap_find_first_free(struct cardmap *map)
2752 {
2753         struct cardmap *p;
2754         unsigned int nr = 0;
2755         int i;
2756
2757         if ((p = map) == NULL)
2758                 return 0;
2759         for (;;) {
2760                 i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
2761                 if (i >= CARDMAP_WIDTH) {
2762                         if (p->parent == NULL)
2763                                 return CARDMAP_WIDTH << p->shift;
2764                         p = p->parent;
2765                         i = (nr >> p->shift) & CARDMAP_MASK;
2766                         set_bit(i, &p->inuse);
2767                         continue;
2768                 }
2769                 nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
2770                 if (p->shift == 0 || p->ptr[i] == NULL)
2771                         return nr;
2772                 p = p->ptr[i];
2773         }
2774 }
2775
2776 static void cardmap_destroy(struct cardmap **pmap)
2777 {
2778         struct cardmap *p, *np;
2779         int i;
2780
2781         for (p = *pmap; p != NULL; p = np) {
2782                 if (p->shift != 0) {
2783                         for (i = 0; i < CARDMAP_WIDTH; ++i)
2784                                 if (p->ptr[i] != NULL)
2785                                         break;
2786                         if (i < CARDMAP_WIDTH) {
2787                                 np = p->ptr[i];
2788                                 p->ptr[i] = NULL;
2789                                 continue;
2790                         }
2791                 }
2792                 np = p->parent;
2793                 kfree(p);
2794         }
2795         *pmap = NULL;
2796 }
2797
2798 /* Module/initialization stuff */
2799
2800 module_init(ppp_init);
2801 module_exit(ppp_cleanup);
2802
2803 EXPORT_SYMBOL(ppp_register_channel);
2804 EXPORT_SYMBOL(ppp_unregister_channel);
2805 EXPORT_SYMBOL(ppp_channel_index);
2806 EXPORT_SYMBOL(ppp_unit_number);
2807 EXPORT_SYMBOL(ppp_input);
2808 EXPORT_SYMBOL(ppp_input_error);
2809 EXPORT_SYMBOL(ppp_output_wakeup);
2810 EXPORT_SYMBOL(ppp_register_compressor);
2811 EXPORT_SYMBOL(ppp_unregister_compressor);
2812 MODULE_LICENSE("GPL");
2813 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2814 MODULE_ALIAS("/dev/ppp");