git.oblomov.eu Git - linux-2.6/blob - drivers/net/ppp_generic.c

   1 /*
   2  * Generic PPP layer for Linux.
   3  *
   4  * Copyright 1999-2002 Paul Mackerras.
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  *
  11  * The generic PPP layer handles the PPP network interfaces, the
  12  * /dev/ppp device, packet and VJ compression, and multilink.
  13  * It talks to PPP `channels' via the interface defined in
  14  * include/linux/ppp_channel.h.  Channels provide the basic means for
  15  * sending and receiving PPP frames on some kind of communications
  16  * channel.
  17  *
  18  * Part of the code in this driver was inspired by the old async-only
  19  * PPP driver, written by Michael Callahan and Al Longyear, and
  20  * subsequently hacked by Paul Mackerras.
  21  *
  22  * ==FILEVERSION 20041108==
  23  */
  24
  25 #include <linux/module.h>
  26 #include <linux/kernel.h>
  27 #include <linux/kmod.h>
  28 #include <linux/init.h>
  29 #include <linux/list.h>
  30 #include <linux/netdevice.h>
  31 #include <linux/poll.h>
  32 #include <linux/ppp_defs.h>
  33 #include <linux/filter.h>
  34 #include <linux/if_ppp.h>
  35 #include <linux/ppp_channel.h>
  36 #include <linux/ppp-comp.h>
  37 #include <linux/skbuff.h>
  38 #include <linux/rtnetlink.h>
  39 #include <linux/if_arp.h>
  40 #include <linux/ip.h>
  41 #include <linux/tcp.h>
  42 #include <linux/spinlock.h>
  43 #include <linux/rwsem.h>
  44 #include <linux/stddef.h>
  45 #include <linux/device.h>
  46 #include <linux/mutex.h>
  47 #include <net/slhc_vj.h>
  48 #include <asm/atomic.h>
  49
  50 #define PPP_VERSION     "2.4.2"
  51
  52 /*
  53  * Network protocols we support.
  54  */
  55 #define NP_IP   0               /* Internet Protocol V4 */
  56 #define NP_IPV6 1               /* Internet Protocol V6 */
  57 #define NP_IPX  2               /* IPX protocol */
  58 #define NP_AT   3               /* Appletalk protocol */
  59 #define NP_MPLS_UC 4            /* MPLS unicast */
  60 #define NP_MPLS_MC 5            /* MPLS multicast */
  61 #define NUM_NP  6               /* Number of NPs. */
  62
  63 #define MPHDRLEN        6       /* multilink protocol header length */
  64 #define MPHDRLEN_SSN    4       /* ditto with short sequence numbers */
  65 #define MIN_FRAG_SIZE   64
  66
  67 /*
  68  * An instance of /dev/ppp can be associated with either a ppp
  69  * interface unit or a ppp channel.  In both cases, file->private_data
  70  * points to one of these.
  71  */
  72 struct ppp_file {
  73         enum {
  74                 INTERFACE=1, CHANNEL
  75         }               kind;
  76         struct sk_buff_head xq;         /* pppd transmit queue */
  77         struct sk_buff_head rq;         /* receive queue for pppd */
  78         wait_queue_head_t rwait;        /* for poll on reading /dev/ppp */
  79         atomic_t        refcnt;         /* # refs (incl /dev/ppp attached) */
  80         int             hdrlen;         /* space to leave for headers */
  81         int             index;          /* interface unit / channel number */
  82         int             dead;           /* unit/channel has been shut down */
  83 };
  84
  85 #define PF_TO_X(pf, X)          container_of(pf, X, file)
  86
  87 #define PF_TO_PPP(pf)           PF_TO_X(pf, struct ppp)
  88 #define PF_TO_CHANNEL(pf)       PF_TO_X(pf, struct channel)
  89
  90 /*
  91  * Data structure describing one ppp unit.
  92  * A ppp unit corresponds to a ppp network interface device
  93  * and represents a multilink bundle.
  94  * It can have 0 or more ppp channels connected to it.
  95  */
  96 struct ppp {
  97         struct ppp_file file;           /* stuff for read/write/poll 0 */
  98         struct file     *owner;         /* file that owns this unit 48 */
  99         struct list_head channels;      /* list of attached channels 4c */
 100         int             n_channels;     /* how many channels are attached 54 */
 101         spinlock_t      rlock;          /* lock for receive side 58 */
 102         spinlock_t      wlock;          /* lock for transmit side 5c */
 103         int             mru;            /* max receive unit 60 */
 104         unsigned int    flags;          /* control bits 64 */
 105         unsigned int    xstate;         /* transmit state bits 68 */
 106         unsigned int    rstate;         /* receive state bits 6c */
 107         int             debug;          /* debug flags 70 */
 108         struct slcompress *vj;          /* state for VJ header compression */
 109         enum NPmode     npmode[NUM_NP]; /* what to do with each net proto 78 */
 110         struct sk_buff  *xmit_pending;  /* a packet ready to go out 88 */
 111         struct compressor *xcomp;       /* transmit packet compressor 8c */
 112         void            *xc_state;      /* its internal state 90 */
 113         struct compressor *rcomp;       /* receive decompressor 94 */
 114         void            *rc_state;      /* its internal state 98 */
 115         unsigned long   last_xmit;      /* jiffies when last pkt sent 9c */
 116         unsigned long   last_recv;      /* jiffies when last pkt rcvd a0 */
 117         struct net_device *dev;         /* network interface device a4 */
 118 #ifdef CONFIG_PPP_MULTILINK
 119         int             nxchan;         /* next channel to send something on */
 120         u32             nxseq;          /* next sequence number to send */
 121         int             mrru;           /* MP: max reconst. receive unit */
 122         u32             nextseq;        /* MP: seq no of next packet */
 123         u32             minseq;         /* MP: min of most recent seqnos */
 124         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
 125 #endif /* CONFIG_PPP_MULTILINK */
 126 #ifdef CONFIG_PPP_FILTER
 127         struct sock_filter *pass_filter;        /* filter for packets to pass */
 128         struct sock_filter *active_filter;/* filter for pkts to reset idle */
 129         unsigned pass_len, active_len;
 130 #endif /* CONFIG_PPP_FILTER */
 131 };
 132
 133 /*
 134  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
 135  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
 136  * SC_MUST_COMP
 137  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
 138  * Bits in xstate: SC_COMP_RUN
 139  */
 140 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
 141                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
 142                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
 143
 144 /*
 145  * Private data structure for each channel.
 146  * This includes the data structure used for multilink.
 147  */
 148 struct channel {
 149         struct ppp_file file;           /* stuff for read/write/poll */
 150         struct list_head list;          /* link in all/new_channels list */
 151         struct ppp_channel *chan;       /* public channel data structure */
 152         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
 153         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
 154         struct ppp      *ppp;           /* ppp unit we're connected to */
 155         struct list_head clist;         /* link in list of channels per unit */
 156         rwlock_t        upl;            /* protects `ppp' */
 157 #ifdef CONFIG_PPP_MULTILINK
 158         u8              avail;          /* flag used in multilink stuff */
 159         u8              had_frag;       /* >= 1 fragments have been sent */
 160         u32             lastseq;        /* MP: last sequence # received */
 161 #endif /* CONFIG_PPP_MULTILINK */
 162 };
 163
 164 /*
 165  * SMP locking issues:
 166  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
 167  * list and the ppp.n_channels field, you need to take both locks
 168  * before you modify them.
 169  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
 170  * channel.downl.
 171  */
 172
 173 /*
 174  * A cardmap represents a mapping from unsigned integers to pointers,
 175  * and provides a fast "find lowest unused number" operation.
 176  * It uses a broad (32-way) tree with a bitmap at each level.
 177  * It is designed to be space-efficient for small numbers of entries
 178  * and time-efficient for large numbers of entries.
 179  */
 180 #define CARDMAP_ORDER   5
 181 #define CARDMAP_WIDTH   (1U << CARDMAP_ORDER)
 182 #define CARDMAP_MASK    (CARDMAP_WIDTH - 1)
 183
 184 struct cardmap {
 185         int shift;
 186         unsigned long inuse;
 187         struct cardmap *parent;
 188         void *ptr[CARDMAP_WIDTH];
 189 };
 190 static void *cardmap_get(struct cardmap *map, unsigned int nr);
 191 static int cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
 192 static unsigned int cardmap_find_first_free(struct cardmap *map);
 193 static void cardmap_destroy(struct cardmap **map);
 194
 195 /*
 196  * all_ppp_mutex protects the all_ppp_units mapping.
 197  * It also ensures that finding a ppp unit in the all_ppp_units map
 198  * and updating its file.refcnt field is atomic.
 199  */
 200 static DEFINE_MUTEX(all_ppp_mutex);
 201 static struct cardmap *all_ppp_units;
 202 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 203
 204 /*
 205  * all_channels_lock protects all_channels and last_channel_index,
 206  * and the atomicity of find a channel and updating its file.refcnt
 207  * field.
 208  */
 209 static DEFINE_SPINLOCK(all_channels_lock);
 210 static LIST_HEAD(all_channels);
 211 static LIST_HEAD(new_channels);
 212 static int last_channel_index;
 213 static atomic_t channel_count = ATOMIC_INIT(0);
 214
 215 /* Get the PPP protocol number from a skb */
 216 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
 217
 218 /* We limit the length of ppp->file.rq to this (arbitrary) value */
 219 #define PPP_MAX_RQLEN   32
 220
 221 /*
 222  * Maximum number of multilink fragments queued up.
 223  * This has to be large enough to cope with the maximum latency of
 224  * the slowest channel relative to the others.  Strictly it should
 225  * depend on the number of channels and their characteristics.
 226  */
 227 #define PPP_MP_MAX_QLEN 128
 228
 229 /* Multilink header bits. */
 230 #define B       0x80            /* this fragment begins a packet */
 231 #define E       0x40            /* this fragment ends a packet */
 232
 233 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
 234 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
 235 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
 236
 237 /* Prototypes. */
 238 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 239                                 unsigned int cmd, unsigned long arg);
 240 static void ppp_xmit_process(struct ppp *ppp);
 241 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
 242 static void ppp_push(struct ppp *ppp);
 243 static void ppp_channel_push(struct channel *pch);
 244 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
 245                               struct channel *pch);
 246 static void ppp_receive_error(struct ppp *ppp);
 247 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
 248 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
 249                                             struct sk_buff *skb);
 250 #ifdef CONFIG_PPP_MULTILINK
 251 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
 252                                 struct channel *pch);
 253 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
 254 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
 255 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
 256 #endif /* CONFIG_PPP_MULTILINK */
 257 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
 258 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
 259 static void ppp_ccp_closed(struct ppp *ppp);
 260 static struct compressor *find_compressor(int type);
 261 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
 262 static struct ppp *ppp_create_interface(int unit, int *retp);
 263 static void init_ppp_file(struct ppp_file *pf, int kind);
 264 static void ppp_shutdown_interface(struct ppp *ppp);
 265 static void ppp_destroy_interface(struct ppp *ppp);
 266 static struct ppp *ppp_find_unit(int unit);
 267 static struct channel *ppp_find_channel(int unit);
 268 static int ppp_connect_channel(struct channel *pch, int unit);
 269 static int ppp_disconnect_channel(struct channel *pch);
 270 static void ppp_destroy_channel(struct channel *pch);
 271
 272 static struct class *ppp_class;
 273
 274 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
 275 static inline int proto_to_npindex(int proto)
 276 {
 277         switch (proto) {
 278         case PPP_IP:
 279                 return NP_IP;
 280         case PPP_IPV6:
 281                 return NP_IPV6;
 282         case PPP_IPX:
 283                 return NP_IPX;
 284         case PPP_AT:
 285                 return NP_AT;
 286         case PPP_MPLS_UC:
 287                 return NP_MPLS_UC;
 288         case PPP_MPLS_MC:
 289                 return NP_MPLS_MC;
 290         }
 291         return -EINVAL;
 292 }
 293
 294 /* Translates an NP index into a PPP protocol number */
 295 static const int npindex_to_proto[NUM_NP] = {
 296         PPP_IP,
 297         PPP_IPV6,
 298         PPP_IPX,
 299         PPP_AT,
 300         PPP_MPLS_UC,
 301         PPP_MPLS_MC,
 302 };
 303
 304 /* Translates an ethertype into an NP index */
 305 static inline int ethertype_to_npindex(int ethertype)
 306 {
 307         switch (ethertype) {
 308         case ETH_P_IP:
 309                 return NP_IP;
 310         case ETH_P_IPV6:
 311                 return NP_IPV6;
 312         case ETH_P_IPX:
 313                 return NP_IPX;
 314         case ETH_P_PPPTALK:
 315         case ETH_P_ATALK:
 316                 return NP_AT;
 317         case ETH_P_MPLS_UC:
 318                 return NP_MPLS_UC;
 319         case ETH_P_MPLS_MC:
 320                 return NP_MPLS_MC;
 321         }
 322         return -1;
 323 }
 324
 325 /* Translates an NP index into an ethertype */
 326 static const int npindex_to_ethertype[NUM_NP] = {
 327         ETH_P_IP,
 328         ETH_P_IPV6,
 329         ETH_P_IPX,
 330         ETH_P_PPPTALK,
 331         ETH_P_MPLS_UC,
 332         ETH_P_MPLS_MC,
 333 };
 334
 335 /*
 336  * Locking shorthand.
 337  */
 338 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
 339 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
 340 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
 341 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
 342 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
 343                                      ppp_recv_lock(ppp); } while (0)
 344 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
 345                                      ppp_xmit_unlock(ppp); } while (0)
 346
 347 /*
 348  * /dev/ppp device routines.
 349  * The /dev/ppp device is used by pppd to control the ppp unit.
 350  * It supports the read, write, ioctl and poll functions.
 351  * Open instances of /dev/ppp can be in one of three states:
 352  * unattached, attached to a ppp unit, or attached to a ppp channel.
 353  */
 354 /* No BKL needed here */
 355 static int ppp_open(struct inode *inode, struct file *file)
 356 {
 357         /*
 358          * This could (should?) be enforced by the permissions on /dev/ppp.
 359          */
 360         if (!capable(CAP_NET_ADMIN))
 361                 return -EPERM;
 362         return 0;
 363 }
 364
 365 static int ppp_release(struct inode *inode, struct file *file)
 366 {
 367         struct ppp_file *pf = file->private_data;
 368         struct ppp *ppp;
 369
 370         if (pf) {
 371                 file->private_data = NULL;
 372                 if (pf->kind == INTERFACE) {
 373                         ppp = PF_TO_PPP(pf);
 374                         if (file == ppp->owner)
 375                                 ppp_shutdown_interface(ppp);
 376                 }
 377                 if (atomic_dec_and_test(&pf->refcnt)) {
 378                         switch (pf->kind) {
 379                         case INTERFACE:
 380                                 ppp_destroy_interface(PF_TO_PPP(pf));
 381                                 break;
 382                         case CHANNEL:
 383                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
 384                                 break;
 385                         }
 386                 }
 387         }
 388         return 0;
 389 }
 390
 391 static ssize_t ppp_read(struct file *file, char __user *buf,
 392                         size_t count, loff_t *ppos)
 393 {
 394         struct ppp_file *pf = file->private_data;
 395         DECLARE_WAITQUEUE(wait, current);
 396         ssize_t ret;
 397         struct sk_buff *skb = NULL;
 398
 399         ret = count;
 400
 401         if (!pf)
 402                 return -ENXIO;
 403         add_wait_queue(&pf->rwait, &wait);
 404         for (;;) {
 405                 set_current_state(TASK_INTERRUPTIBLE);
 406                 skb = skb_dequeue(&pf->rq);
 407                 if (skb)
 408                         break;
 409                 ret = 0;
 410                 if (pf->dead)
 411                         break;
 412                 if (pf->kind == INTERFACE) {
 413                         /*
 414                          * Return 0 (EOF) on an interface that has no
 415                          * channels connected, unless it is looping
 416                          * network traffic (demand mode).
 417                          */
 418                         struct ppp *ppp = PF_TO_PPP(pf);
 419                         if (ppp->n_channels == 0
 420                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 421                                 break;
 422                 }
 423                 ret = -EAGAIN;
 424                 if (file->f_flags & O_NONBLOCK)
 425                         break;
 426                 ret = -ERESTARTSYS;
 427                 if (signal_pending(current))
 428                         break;
 429                 schedule();
 430         }
 431         set_current_state(TASK_RUNNING);
 432         remove_wait_queue(&pf->rwait, &wait);
 433
 434         if (!skb)
 435                 goto out;
 436
 437         ret = -EOVERFLOW;
 438         if (skb->len > count)
 439                 goto outf;
 440         ret = -EFAULT;
 441         if (copy_to_user(buf, skb->data, skb->len))
 442                 goto outf;
 443         ret = skb->len;
 444
 445  outf:
 446         kfree_skb(skb);
 447  out:
 448         return ret;
 449 }
 450
 451 static ssize_t ppp_write(struct file *file, const char __user *buf,
 452                          size_t count, loff_t *ppos)
 453 {
 454         struct ppp_file *pf = file->private_data;
 455         struct sk_buff *skb;
 456         ssize_t ret;
 457
 458         if (!pf)
 459                 return -ENXIO;
 460         ret = -ENOMEM;
 461         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
 462         if (!skb)
 463                 goto out;
 464         skb_reserve(skb, pf->hdrlen);
 465         ret = -EFAULT;
 466         if (copy_from_user(skb_put(skb, count), buf, count)) {
 467                 kfree_skb(skb);
 468                 goto out;
 469         }
 470
 471         skb_queue_tail(&pf->xq, skb);
 472
 473         switch (pf->kind) {
 474         case INTERFACE:
 475                 ppp_xmit_process(PF_TO_PPP(pf));
 476                 break;
 477         case CHANNEL:
 478                 ppp_channel_push(PF_TO_CHANNEL(pf));
 479                 break;
 480         }
 481
 482         ret = count;
 483
 484  out:
 485         return ret;
 486 }
 487
 488 /* No kernel lock - fine */
 489 static unsigned int ppp_poll(struct file *file, poll_table *wait)
 490 {
 491         struct ppp_file *pf = file->private_data;
 492         unsigned int mask;
 493
 494         if (!pf)
 495                 return 0;
 496         poll_wait(file, &pf->rwait, wait);
 497         mask = POLLOUT | POLLWRNORM;
 498         if (skb_peek(&pf->rq))
 499                 mask |= POLLIN | POLLRDNORM;
 500         if (pf->dead)
 501                 mask |= POLLHUP;
 502         else if (pf->kind == INTERFACE) {
 503                 /* see comment in ppp_read */
 504                 struct ppp *ppp = PF_TO_PPP(pf);
 505                 if (ppp->n_channels == 0
 506                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 507                         mask |= POLLIN | POLLRDNORM;
 508         }
 509
 510         return mask;
 511 }
 512
 513 #ifdef CONFIG_PPP_FILTER
 514 static int get_filter(void __user *arg, struct sock_filter **p)
 515 {
 516         struct sock_fprog uprog;
 517         struct sock_filter *code = NULL;
 518         int len, err;
 519
 520         if (copy_from_user(&uprog, arg, sizeof(uprog)))
 521                 return -EFAULT;
 522
 523         if (!uprog.len) {
 524                 *p = NULL;
 525                 return 0;
 526         }
 527
 528         len = uprog.len * sizeof(struct sock_filter);
 529         code = kmalloc(len, GFP_KERNEL);
 530         if (code == NULL)
 531                 return -ENOMEM;
 532
 533         if (copy_from_user(code, uprog.filter, len)) {
 534                 kfree(code);
 535                 return -EFAULT;
 536         }
 537
 538         err = sk_chk_filter(code, uprog.len);
 539         if (err) {
 540                 kfree(code);
 541                 return err;
 542         }
 543
 544         *p = code;
 545         return uprog.len;
 546 }
 547 #endif /* CONFIG_PPP_FILTER */
 548
 549 static int ppp_ioctl(struct inode *inode, struct file *file,
 550                      unsigned int cmd, unsigned long arg)
 551 {
 552         struct ppp_file *pf = file->private_data;
 553         struct ppp *ppp;
 554         int err = -EFAULT, val, val2, i;
 555         struct ppp_idle idle;
 556         struct npioctl npi;
 557         int unit, cflags;
 558         struct slcompress *vj;
 559         void __user *argp = (void __user *)arg;
 560         int __user *p = argp;
 561
 562         if (!pf)
 563                 return ppp_unattached_ioctl(pf, file, cmd, arg);
 564
 565         if (cmd == PPPIOCDETACH) {
 566                 /*
 567                  * We have to be careful here... if the file descriptor
 568                  * has been dup'd, we could have another process in the
 569                  * middle of a poll using the same file *, so we had
 570                  * better not free the interface data structures -
 571                  * instead we fail the ioctl.  Even in this case, we
 572                  * shut down the interface if we are the owner of it.
 573                  * Actually, we should get rid of PPPIOCDETACH, userland
 574                  * (i.e. pppd) could achieve the same effect by closing
 575                  * this fd and reopening /dev/ppp.
 576                  */
 577                 err = -EINVAL;
 578                 if (pf->kind == INTERFACE) {
 579                         ppp = PF_TO_PPP(pf);
 580                         if (file == ppp->owner)
 581                                 ppp_shutdown_interface(ppp);
 582                 }
 583                 if (atomic_read(&file->f_count) <= 2) {
 584                         ppp_release(inode, file);
 585                         err = 0;
 586                 } else
 587                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%d\n",
 588                                atomic_read(&file->f_count));
 589                 return err;
 590         }
 591
 592         if (pf->kind == CHANNEL) {
 593                 struct channel *pch = PF_TO_CHANNEL(pf);
 594                 struct ppp_channel *chan;
 595
 596                 switch (cmd) {
 597                 case PPPIOCCONNECT:
 598                         if (get_user(unit, p))
 599                                 break;
 600                         err = ppp_connect_channel(pch, unit);
 601                         break;
 602
 603                 case PPPIOCDISCONN:
 604                         err = ppp_disconnect_channel(pch);
 605                         break;
 606
 607                 default:
 608                         down_read(&pch->chan_sem);
 609                         chan = pch->chan;
 610                         err = -ENOTTY;
 611                         if (chan && chan->ops->ioctl)
 612                                 err = chan->ops->ioctl(chan, cmd, arg);
 613                         up_read(&pch->chan_sem);
 614                 }
 615                 return err;
 616         }
 617
 618         if (pf->kind != INTERFACE) {
 619                 /* can't happen */
 620                 printk(KERN_ERR "PPP: not interface or channel??\n");
 621                 return -EINVAL;
 622         }
 623
 624         ppp = PF_TO_PPP(pf);
 625         switch (cmd) {
 626         case PPPIOCSMRU:
 627                 if (get_user(val, p))
 628                         break;
 629                 ppp->mru = val;
 630                 err = 0;
 631                 break;
 632
 633         case PPPIOCSFLAGS:
 634                 if (get_user(val, p))
 635                         break;
 636                 ppp_lock(ppp);
 637                 cflags = ppp->flags & ~val;
 638                 ppp->flags = val & SC_FLAG_BITS;
 639                 ppp_unlock(ppp);
 640                 if (cflags & SC_CCP_OPEN)
 641                         ppp_ccp_closed(ppp);
 642                 err = 0;
 643                 break;
 644
 645         case PPPIOCGFLAGS:
 646                 val = ppp->flags | ppp->xstate | ppp->rstate;
 647                 if (put_user(val, p))
 648                         break;
 649                 err = 0;
 650                 break;
 651
 652         case PPPIOCSCOMPRESS:
 653                 err = ppp_set_compress(ppp, arg);
 654                 break;
 655
 656         case PPPIOCGUNIT:
 657                 if (put_user(ppp->file.index, p))
 658                         break;
 659                 err = 0;
 660                 break;
 661
 662         case PPPIOCSDEBUG:
 663                 if (get_user(val, p))
 664                         break;
 665                 ppp->debug = val;
 666                 err = 0;
 667                 break;
 668
 669         case PPPIOCGDEBUG:
 670                 if (put_user(ppp->debug, p))
 671                         break;
 672                 err = 0;
 673                 break;
 674
 675         case PPPIOCGIDLE:
 676                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 677                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
 678                 if (copy_to_user(argp, &idle, sizeof(idle)))
 679                         break;
 680                 err = 0;
 681                 break;
 682
 683         case PPPIOCSMAXCID:
 684                 if (get_user(val, p))
 685                         break;
 686                 val2 = 15;
 687                 if ((val >> 16) != 0) {
 688                         val2 = val >> 16;
 689                         val &= 0xffff;
 690                 }
 691                 vj = slhc_init(val2+1, val+1);
 692                 if (!vj) {
 693                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
 694                         err = -ENOMEM;
 695                         break;
 696                 }
 697                 ppp_lock(ppp);
 698                 if (ppp->vj)
 699                         slhc_free(ppp->vj);
 700                 ppp->vj = vj;
 701                 ppp_unlock(ppp);
 702                 err = 0;
 703                 break;
 704
 705         case PPPIOCGNPMODE:
 706         case PPPIOCSNPMODE:
 707                 if (copy_from_user(&npi, argp, sizeof(npi)))
 708                         break;
 709                 err = proto_to_npindex(npi.protocol);
 710                 if (err < 0)
 711                         break;
 712                 i = err;
 713                 if (cmd == PPPIOCGNPMODE) {
 714                         err = -EFAULT;
 715                         npi.mode = ppp->npmode[i];
 716                         if (copy_to_user(argp, &npi, sizeof(npi)))
 717                                 break;
 718                 } else {
 719                         ppp->npmode[i] = npi.mode;
 720                         /* we may be able to transmit more packets now (??) */
 721                         netif_wake_queue(ppp->dev);
 722                 }
 723                 err = 0;
 724                 break;
 725
 726 #ifdef CONFIG_PPP_FILTER
 727         case PPPIOCSPASS:
 728         {
 729                 struct sock_filter *code;
 730                 err = get_filter(argp, &code);
 731                 if (err >= 0) {
 732                         ppp_lock(ppp);
 733                         kfree(ppp->pass_filter);
 734                         ppp->pass_filter = code;
 735                         ppp->pass_len = err;
 736                         ppp_unlock(ppp);
 737                         err = 0;
 738                 }
 739                 break;
 740         }
 741         case PPPIOCSACTIVE:
 742         {
 743                 struct sock_filter *code;
 744                 err = get_filter(argp, &code);
 745                 if (err >= 0) {
 746                         ppp_lock(ppp);
 747                         kfree(ppp->active_filter);
 748                         ppp->active_filter = code;
 749                         ppp->active_len = err;
 750                         ppp_unlock(ppp);
 751                         err = 0;
 752                 }
 753                 break;
 754         }
 755 #endif /* CONFIG_PPP_FILTER */
 756
 757 #ifdef CONFIG_PPP_MULTILINK
 758         case PPPIOCSMRRU:
 759                 if (get_user(val, p))
 760                         break;
 761                 ppp_recv_lock(ppp);
 762                 ppp->mrru = val;
 763                 ppp_recv_unlock(ppp);
 764                 err = 0;
 765                 break;
 766 #endif /* CONFIG_PPP_MULTILINK */
 767
 768         default:
 769                 err = -ENOTTY;
 770         }
 771
 772         return err;
 773 }
 774
 775 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 776                                 unsigned int cmd, unsigned long arg)
 777 {
 778         int unit, err = -EFAULT;
 779         struct ppp *ppp;
 780         struct channel *chan;
 781         int __user *p = (int __user *)arg;
 782
 783         switch (cmd) {
 784         case PPPIOCNEWUNIT:
 785                 /* Create a new ppp unit */
 786                 if (get_user(unit, p))
 787                         break;
 788                 ppp = ppp_create_interface(unit, &err);
 789                 if (!ppp)
 790                         break;
 791                 file->private_data = &ppp->file;
 792                 ppp->owner = file;
 793                 err = -EFAULT;
 794                 if (put_user(ppp->file.index, p))
 795                         break;
 796                 err = 0;
 797                 break;
 798
 799         case PPPIOCATTACH:
 800                 /* Attach to an existing ppp unit */
 801                 if (get_user(unit, p))
 802                         break;
 803                 mutex_lock(&all_ppp_mutex);
 804                 err = -ENXIO;
 805                 ppp = ppp_find_unit(unit);
 806                 if (ppp) {
 807                         atomic_inc(&ppp->file.refcnt);
 808                         file->private_data = &ppp->file;
 809                         err = 0;
 810                 }
 811                 mutex_unlock(&all_ppp_mutex);
 812                 break;
 813
 814         case PPPIOCATTCHAN:
 815                 if (get_user(unit, p))
 816                         break;
 817                 spin_lock_bh(&all_channels_lock);
 818                 err = -ENXIO;
 819                 chan = ppp_find_channel(unit);
 820                 if (chan) {
 821                         atomic_inc(&chan->file.refcnt);
 822                         file->private_data = &chan->file;
 823                         err = 0;
 824                 }
 825                 spin_unlock_bh(&all_channels_lock);
 826                 break;
 827
 828         default:
 829                 err = -ENOTTY;
 830         }
 831         return err;
 832 }
 833
 834 static const struct file_operations ppp_device_fops = {
 835         .owner          = THIS_MODULE,
 836         .read           = ppp_read,
 837         .write          = ppp_write,
 838         .poll           = ppp_poll,
 839         .ioctl          = ppp_ioctl,
 840         .open           = ppp_open,
 841         .release        = ppp_release
 842 };
 843
 844 #define PPP_MAJOR       108
 845
 846 /* Called at boot time if ppp is compiled into the kernel,
 847    or at module load time (from init_module) if compiled as a module. */
 848 static int __init ppp_init(void)
 849 {
 850         int err;
 851
 852         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
 853         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
 854         if (!err) {
 855                 ppp_class = class_create(THIS_MODULE, "ppp");
 856                 if (IS_ERR(ppp_class)) {
 857                         err = PTR_ERR(ppp_class);
 858                         goto out_chrdev;
 859                 }
 860                 device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), "ppp");
 861         }
 862
 863 out:
 864         if (err)
 865                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
 866         return err;
 867
 868 out_chrdev:
 869         unregister_chrdev(PPP_MAJOR, "ppp");
 870         goto out;
 871 }
 872
 873 /*
 874  * Network interface unit routines.
 875  */
 876 static int
 877 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 878 {
 879         struct ppp *ppp = (struct ppp *) dev->priv;
 880         int npi, proto;
 881         unsigned char *pp;
 882
 883         npi = ethertype_to_npindex(ntohs(skb->protocol));
 884         if (npi < 0)
 885                 goto outf;
 886
 887         /* Drop, accept or reject the packet */
 888         switch (ppp->npmode[npi]) {
 889         case NPMODE_PASS:
 890                 break;
 891         case NPMODE_QUEUE:
 892                 /* it would be nice to have a way to tell the network
 893                    system to queue this one up for later. */
 894                 goto outf;
 895         case NPMODE_DROP:
 896         case NPMODE_ERROR:
 897                 goto outf;
 898         }
 899
 900         /* Put the 2-byte PPP protocol number on the front,
 901            making sure there is room for the address and control fields. */
 902         if (skb_cow_head(skb, PPP_HDRLEN))
 903                 goto outf;
 904
 905         pp = skb_push(skb, 2);
 906         proto = npindex_to_proto[npi];
 907         pp[0] = proto >> 8;
 908         pp[1] = proto;
 909
 910         netif_stop_queue(dev);
 911         skb_queue_tail(&ppp->file.xq, skb);
 912         ppp_xmit_process(ppp);
 913         return 0;
 914
 915  outf:
 916         kfree_skb(skb);
 917         ++ppp->dev->stats.tx_dropped;
 918         return 0;
 919 }
 920
 921 static int
 922 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 923 {
 924         struct ppp *ppp = dev->priv;
 925         int err = -EFAULT;
 926         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
 927         struct ppp_stats stats;
 928         struct ppp_comp_stats cstats;
 929         char *vers;
 930
 931         switch (cmd) {
 932         case SIOCGPPPSTATS:
 933                 ppp_get_stats(ppp, &stats);
 934                 if (copy_to_user(addr, &stats, sizeof(stats)))
 935                         break;
 936                 err = 0;
 937                 break;
 938
 939         case SIOCGPPPCSTATS:
 940                 memset(&cstats, 0, sizeof(cstats));
 941                 if (ppp->xc_state)
 942                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
 943                 if (ppp->rc_state)
 944                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
 945                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
 946                         break;
 947                 err = 0;
 948                 break;
 949
 950         case SIOCGPPPVER:
 951                 vers = PPP_VERSION;
 952                 if (copy_to_user(addr, vers, strlen(vers) + 1))
 953                         break;
 954                 err = 0;
 955                 break;
 956
 957         default:
 958                 err = -EINVAL;
 959         }
 960
 961         return err;
 962 }
 963
 964 static void ppp_setup(struct net_device *dev)
 965 {
 966         dev->hard_header_len = PPP_HDRLEN;
 967         dev->mtu = PPP_MTU;
 968         dev->addr_len = 0;
 969         dev->tx_queue_len = 3;
 970         dev->type = ARPHRD_PPP;
 971         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
 972 }
 973
 974 /*
 975  * Transmit-side routines.
 976  */
 977
 978 /*
 979  * Called to do any work queued up on the transmit side
 980  * that can now be done.
 981  */
 982 static void
 983 ppp_xmit_process(struct ppp *ppp)
 984 {
 985         struct sk_buff *skb;
 986
 987         ppp_xmit_lock(ppp);
 988         if (ppp->dev) {
 989                 ppp_push(ppp);
 990                 while (!ppp->xmit_pending
 991                        && (skb = skb_dequeue(&ppp->file.xq)))
 992                         ppp_send_frame(ppp, skb);
 993                 /* If there's no work left to do, tell the core net
 994                    code that we can accept some more. */
 995                 if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
 996                         netif_wake_queue(ppp->dev);
 997         }
 998         ppp_xmit_unlock(ppp);
 999 }
1000
1001 static inline struct sk_buff *
1002 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1003 {
1004         struct sk_buff *new_skb;
1005         int len;
1006         int new_skb_size = ppp->dev->mtu +
1007                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1008         int compressor_skb_size = ppp->dev->mtu +
1009                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1010         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1011         if (!new_skb) {
1012                 if (net_ratelimit())
1013                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1014                 return NULL;
1015         }
1016         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1017                 skb_reserve(new_skb,
1018                             ppp->dev->hard_header_len - PPP_HDRLEN);
1019
1020         /* compressor still expects A/C bytes in hdr */
1021         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1022                                    new_skb->data, skb->len + 2,
1023                                    compressor_skb_size);
1024         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1025                 kfree_skb(skb);
1026                 skb = new_skb;
1027                 skb_put(skb, len);
1028                 skb_pull(skb, 2);       /* pull off A/C bytes */
1029         } else if (len == 0) {
1030                 /* didn't compress, or CCP not up yet */
1031                 kfree_skb(new_skb);
1032                 new_skb = skb;
1033         } else {
1034                 /*
1035                  * (len < 0)
1036                  * MPPE requires that we do not send unencrypted
1037                  * frames.  The compressor will return -1 if we
1038                  * should drop the frame.  We cannot simply test
1039                  * the compress_proto because MPPE and MPPC share
1040                  * the same number.
1041                  */
1042                 if (net_ratelimit())
1043                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1044                 kfree_skb(skb);
1045                 kfree_skb(new_skb);
1046                 new_skb = NULL;
1047         }
1048         return new_skb;
1049 }
1050
1051 /*
1052  * Compress and send a frame.
1053  * The caller should have locked the xmit path,
1054  * and xmit_pending should be 0.
1055  */
1056 static void
1057 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1058 {
1059         int proto = PPP_PROTO(skb);
1060         struct sk_buff *new_skb;
1061         int len;
1062         unsigned char *cp;
1063
1064         if (proto < 0x8000) {
1065 #ifdef CONFIG_PPP_FILTER
1066                 /* check if we should pass this packet */
1067                 /* the filter instructions are constructed assuming
1068                    a four-byte PPP header on each packet */
1069                 *skb_push(skb, 2) = 1;
1070                 if (ppp->pass_filter
1071                     && sk_run_filter(skb, ppp->pass_filter,
1072                                      ppp->pass_len) == 0) {
1073                         if (ppp->debug & 1)
1074                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1075                         kfree_skb(skb);
1076                         return;
1077                 }
1078                 /* if this packet passes the active filter, record the time */
1079                 if (!(ppp->active_filter
1080                       && sk_run_filter(skb, ppp->active_filter,
1081                                        ppp->active_len) == 0))
1082                         ppp->last_xmit = jiffies;
1083                 skb_pull(skb, 2);
1084 #else
1085                 /* for data packets, record the time */
1086                 ppp->last_xmit = jiffies;
1087 #endif /* CONFIG_PPP_FILTER */
1088         }
1089
1090         ++ppp->dev->stats.tx_packets;
1091         ppp->dev->stats.tx_bytes += skb->len - 2;
1092
1093         switch (proto) {
1094         case PPP_IP:
1095                 if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1096                         break;
1097                 /* try to do VJ TCP header compression */
1098                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1099                                     GFP_ATOMIC);
1100                 if (!new_skb) {
1101                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1102                         goto drop;
1103                 }
1104                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1105                 cp = skb->data + 2;
1106                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1107                                     new_skb->data + 2, &cp,
1108                                     !(ppp->flags & SC_NO_TCP_CCID));
1109                 if (cp == skb->data + 2) {
1110                         /* didn't compress */
1111                         kfree_skb(new_skb);
1112                 } else {
1113                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1114                                 proto = PPP_VJC_COMP;
1115                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1116                         } else {
1117                                 proto = PPP_VJC_UNCOMP;
1118                                 cp[0] = skb->data[2];
1119                         }
1120                         kfree_skb(skb);
1121                         skb = new_skb;
1122                         cp = skb_put(skb, len + 2);
1123                         cp[0] = 0;
1124                         cp[1] = proto;
1125                 }
1126                 break;
1127
1128         case PPP_CCP:
1129                 /* peek at outbound CCP frames */
1130                 ppp_ccp_peek(ppp, skb, 0);
1131                 break;
1132         }
1133
1134         /* try to do packet compression */
1135         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state
1136             && proto != PPP_LCP && proto != PPP_CCP) {
1137                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1138                         if (net_ratelimit())
1139                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1140                         goto drop;
1141                 }
1142                 skb = pad_compress_skb(ppp, skb);
1143                 if (!skb)
1144                         goto drop;
1145         }
1146
1147         /*
1148          * If we are waiting for traffic (demand dialling),
1149          * queue it up for pppd to receive.
1150          */
1151         if (ppp->flags & SC_LOOP_TRAFFIC) {
1152                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1153                         goto drop;
1154                 skb_queue_tail(&ppp->file.rq, skb);
1155                 wake_up_interruptible(&ppp->file.rwait);
1156                 return;
1157         }
1158
1159         ppp->xmit_pending = skb;
1160         ppp_push(ppp);
1161         return;
1162
1163  drop:
1164         if (skb)
1165                 kfree_skb(skb);
1166         ++ppp->dev->stats.tx_errors;
1167 }
1168
1169 /*
1170  * Try to send the frame in xmit_pending.
1171  * The caller should have the xmit path locked.
1172  */
1173 static void
1174 ppp_push(struct ppp *ppp)
1175 {
1176         struct list_head *list;
1177         struct channel *pch;
1178         struct sk_buff *skb = ppp->xmit_pending;
1179
1180         if (!skb)
1181                 return;
1182
1183         list = &ppp->channels;
1184         if (list_empty(list)) {
1185                 /* nowhere to send the packet, just drop it */
1186                 ppp->xmit_pending = NULL;
1187                 kfree_skb(skb);
1188                 return;
1189         }
1190
1191         if ((ppp->flags & SC_MULTILINK) == 0) {
1192                 /* not doing multilink: send it down the first channel */
1193                 list = list->next;
1194                 pch = list_entry(list, struct channel, clist);
1195
1196                 spin_lock_bh(&pch->downl);
1197                 if (pch->chan) {
1198                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1199                                 ppp->xmit_pending = NULL;
1200                 } else {
1201                         /* channel got unregistered */
1202                         kfree_skb(skb);
1203                         ppp->xmit_pending = NULL;
1204                 }
1205                 spin_unlock_bh(&pch->downl);
1206                 return;
1207         }
1208
1209 #ifdef CONFIG_PPP_MULTILINK
1210         /* Multilink: fragment the packet over as many links
1211            as can take the packet at the moment. */
1212         if (!ppp_mp_explode(ppp, skb))
1213                 return;
1214 #endif /* CONFIG_PPP_MULTILINK */
1215
1216         ppp->xmit_pending = NULL;
1217         kfree_skb(skb);
1218 }
1219
1220 #ifdef CONFIG_PPP_MULTILINK
1221 /*
1222  * Divide a packet to be transmitted into fragments and
1223  * send them out the individual links.
1224  */
1225 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1226 {
1227         int len, fragsize;
1228         int i, bits, hdrlen, mtu;
1229         int flen;
1230         int navail, nfree;
1231         int nbigger;
1232         unsigned char *p, *q;
1233         struct list_head *list;
1234         struct channel *pch;
1235         struct sk_buff *frag;
1236         struct ppp_channel *chan;
1237
1238         nfree = 0;      /* # channels which have no packet already queued */
1239         navail = 0;     /* total # of usable channels (not deregistered) */
1240         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1241         i = 0;
1242         list_for_each_entry(pch, &ppp->channels, clist) {
1243                 navail += pch->avail = (pch->chan != NULL);
1244                 if (pch->avail) {
1245                         if (skb_queue_empty(&pch->file.xq) ||
1246                             !pch->had_frag) {
1247                                 pch->avail = 2;
1248                                 ++nfree;
1249                         }
1250                         if (!pch->had_frag && i < ppp->nxchan)
1251                                 ppp->nxchan = i;
1252                 }
1253                 ++i;
1254         }
1255
1256         /*
1257          * Don't start sending this packet unless at least half of
1258          * the channels are free.  This gives much better TCP
1259          * performance if we have a lot of channels.
1260          */
1261         if (nfree == 0 || nfree < navail / 2)
1262                 return 0;       /* can't take now, leave it in xmit_pending */
1263
1264         /* Do protocol field compression (XXX this should be optional) */
1265         p = skb->data;
1266         len = skb->len;
1267         if (*p == 0) {
1268                 ++p;
1269                 --len;
1270         }
1271
1272         /*
1273          * Decide on fragment size.
1274          * We create a fragment for each free channel regardless of
1275          * how small they are (i.e. even 0 length) in order to minimize
1276          * the time that it will take to detect when a channel drops
1277          * a fragment.
1278          */
1279         fragsize = len;
1280         if (nfree > 1)
1281                 fragsize = DIV_ROUND_UP(fragsize, nfree);
1282         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1283            except if nbigger==0, then they all get fragsize. */
1284         nbigger = len % nfree;
1285
1286         /* skip to the channel after the one we last used
1287            and start at that one */
1288         list = &ppp->channels;
1289         for (i = 0; i < ppp->nxchan; ++i) {
1290                 list = list->next;
1291                 if (list == &ppp->channels) {
1292                         i = 0;
1293                         break;
1294                 }
1295         }
1296
1297         /* create a fragment for each channel */
1298         bits = B;
1299         while (nfree > 0 || len > 0) {
1300                 list = list->next;
1301                 if (list == &ppp->channels) {
1302                         i = 0;
1303                         continue;
1304                 }
1305                 pch = list_entry(list, struct channel, clist);
1306                 ++i;
1307                 if (!pch->avail)
1308                         continue;
1309
1310                 /*
1311                  * Skip this channel if it has a fragment pending already and
1312                  * we haven't given a fragment to all of the free channels.
1313                  */
1314                 if (pch->avail == 1) {
1315                         if (nfree > 0)
1316                                 continue;
1317                 } else {
1318                         --nfree;
1319                         pch->avail = 1;
1320                 }
1321
1322                 /* check the channel's mtu and whether it is still attached. */
1323                 spin_lock_bh(&pch->downl);
1324                 if (pch->chan == NULL) {
1325                         /* can't use this channel, it's being deregistered */
1326                         spin_unlock_bh(&pch->downl);
1327                         pch->avail = 0;
1328                         if (--navail == 0)
1329                                 break;
1330                         continue;
1331                 }
1332
1333                 /*
1334                  * Create a fragment for this channel of
1335                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1336                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1337                  * MTU, so we use mtu = 2 + hdrlen.
1338                  */
1339                 if (fragsize > len)
1340                         fragsize = len;
1341                 flen = fragsize;
1342                 mtu = pch->chan->mtu + 2 - hdrlen;
1343                 if (mtu < 4)
1344                         mtu = 4;
1345                 if (flen > mtu)
1346                         flen = mtu;
1347                 if (flen == len && nfree == 0)
1348                         bits |= E;
1349                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1350                 if (!frag)
1351                         goto noskb;
1352                 q = skb_put(frag, flen + hdrlen);
1353
1354                 /* make the MP header */
1355                 q[0] = PPP_MP >> 8;
1356                 q[1] = PPP_MP;
1357                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1358                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1359                         q[3] = ppp->nxseq;
1360                 } else {
1361                         q[2] = bits;
1362                         q[3] = ppp->nxseq >> 16;
1363                         q[4] = ppp->nxseq >> 8;
1364                         q[5] = ppp->nxseq;
1365                 }
1366
1367                 /*
1368                  * Copy the data in.
1369                  * Unfortunately there is a bug in older versions of
1370                  * the Linux PPP multilink reconstruction code where it
1371                  * drops 0-length fragments.  Therefore we make sure the
1372                  * fragment has at least one byte of data.  Any bytes
1373                  * we add in this situation will end up as padding on the
1374                  * end of the reconstructed packet.
1375                  */
1376                 if (flen == 0)
1377                         *skb_put(frag, 1) = 0;
1378                 else
1379                         memcpy(q + hdrlen, p, flen);
1380
1381                 /* try to send it down the channel */
1382                 chan = pch->chan;
1383                 if (!skb_queue_empty(&pch->file.xq) ||
1384                     !chan->ops->start_xmit(chan, frag))
1385                         skb_queue_tail(&pch->file.xq, frag);
1386                 pch->had_frag = 1;
1387                 p += flen;
1388                 len -= flen;
1389                 ++ppp->nxseq;
1390                 bits = 0;
1391                 spin_unlock_bh(&pch->downl);
1392
1393                 if (--nbigger == 0 && fragsize > 0)
1394                         --fragsize;
1395         }
1396         ppp->nxchan = i;
1397
1398         return 1;
1399
1400  noskb:
1401         spin_unlock_bh(&pch->downl);
1402         if (ppp->debug & 1)
1403                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1404         ++ppp->dev->stats.tx_errors;
1405         ++ppp->nxseq;
1406         return 1;       /* abandon the frame */
1407 }
1408 #endif /* CONFIG_PPP_MULTILINK */
1409
1410 /*
1411  * Try to send data out on a channel.
1412  */
1413 static void
1414 ppp_channel_push(struct channel *pch)
1415 {
1416         struct sk_buff *skb;
1417         struct ppp *ppp;
1418
1419         spin_lock_bh(&pch->downl);
1420         if (pch->chan) {
1421                 while (!skb_queue_empty(&pch->file.xq)) {
1422                         skb = skb_dequeue(&pch->file.xq);
1423                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1424                                 /* put the packet back and try again later */
1425                                 skb_queue_head(&pch->file.xq, skb);
1426                                 break;
1427                         }
1428                 }
1429         } else {
1430                 /* channel got deregistered */
1431                 skb_queue_purge(&pch->file.xq);
1432         }
1433         spin_unlock_bh(&pch->downl);
1434         /* see if there is anything from the attached unit to be sent */
1435         if (skb_queue_empty(&pch->file.xq)) {
1436                 read_lock_bh(&pch->upl);
1437                 ppp = pch->ppp;
1438                 if (ppp)
1439                         ppp_xmit_process(ppp);
1440                 read_unlock_bh(&pch->upl);
1441         }
1442 }
1443
1444 /*
1445  * Receive-side routines.
1446  */
1447
1448 /* misuse a few fields of the skb for MP reconstruction */
1449 #define sequence        priority
1450 #define BEbits          cb[0]
1451
1452 static inline void
1453 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1454 {
1455         ppp_recv_lock(ppp);
1456         /* ppp->dev == 0 means interface is closing down */
1457         if (ppp->dev)
1458                 ppp_receive_frame(ppp, skb, pch);
1459         else
1460                 kfree_skb(skb);
1461         ppp_recv_unlock(ppp);
1462 }
1463
1464 void
1465 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1466 {
1467         struct channel *pch = chan->ppp;
1468         int proto;
1469
1470         if (!pch || skb->len == 0) {
1471                 kfree_skb(skb);
1472                 return;
1473         }
1474
1475         proto = PPP_PROTO(skb);
1476         read_lock_bh(&pch->upl);
1477         if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1478                 /* put it on the channel queue */
1479                 skb_queue_tail(&pch->file.rq, skb);
1480                 /* drop old frames if queue too long */
1481                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1482                        && (skb = skb_dequeue(&pch->file.rq)))
1483                         kfree_skb(skb);
1484                 wake_up_interruptible(&pch->file.rwait);
1485         } else {
1486                 ppp_do_recv(pch->ppp, skb, pch);
1487         }
1488         read_unlock_bh(&pch->upl);
1489 }
1490
1491 /* Put a 0-length skb in the receive queue as an error indication */
1492 void
1493 ppp_input_error(struct ppp_channel *chan, int code)
1494 {
1495         struct channel *pch = chan->ppp;
1496         struct sk_buff *skb;
1497
1498         if (!pch)
1499                 return;
1500
1501         read_lock_bh(&pch->upl);
1502         if (pch->ppp) {
1503                 skb = alloc_skb(0, GFP_ATOMIC);
1504                 if (skb) {
1505                         skb->len = 0;           /* probably unnecessary */
1506                         skb->cb[0] = code;
1507                         ppp_do_recv(pch->ppp, skb, pch);
1508                 }
1509         }
1510         read_unlock_bh(&pch->upl);
1511 }
1512
1513 /*
1514  * We come in here to process a received frame.
1515  * The receive side of the ppp unit is locked.
1516  */
1517 static void
1518 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1519 {
1520         if (pskb_may_pull(skb, 2)) {
1521 #ifdef CONFIG_PPP_MULTILINK
1522                 /* XXX do channel-level decompression here */
1523                 if (PPP_PROTO(skb) == PPP_MP)
1524                         ppp_receive_mp_frame(ppp, skb, pch);
1525                 else
1526 #endif /* CONFIG_PPP_MULTILINK */
1527                         ppp_receive_nonmp_frame(ppp, skb);
1528                 return;
1529         }
1530
1531         if (skb->len > 0)
1532                 /* note: a 0-length skb is used as an error indication */
1533                 ++ppp->dev->stats.rx_length_errors;
1534
1535         kfree_skb(skb);
1536         ppp_receive_error(ppp);
1537 }
1538
1539 static void
1540 ppp_receive_error(struct ppp *ppp)
1541 {
1542         ++ppp->dev->stats.rx_errors;
1543         if (ppp->vj)
1544                 slhc_toss(ppp->vj);
1545 }
1546
1547 static void
1548 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1549 {
1550         struct sk_buff *ns;
1551         int proto, len, npi;
1552
1553         /*
1554          * Decompress the frame, if compressed.
1555          * Note that some decompressors need to see uncompressed frames
1556          * that come in as well as compressed frames.
1557          */
1558         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)
1559             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1560                 skb = ppp_decompress_frame(ppp, skb);
1561
1562         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1563                 goto err;
1564
1565         proto = PPP_PROTO(skb);
1566         switch (proto) {
1567         case PPP_VJC_COMP:
1568                 /* decompress VJ compressed packets */
1569                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1570                         goto err;
1571
1572                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1573                         /* copy to a new sk_buff with more tailroom */
1574                         ns = dev_alloc_skb(skb->len + 128);
1575                         if (!ns) {
1576                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1577                                 goto err;
1578                         }
1579                         skb_reserve(ns, 2);
1580                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1581                         kfree_skb(skb);
1582                         skb = ns;
1583                 }
1584                 else
1585                         skb->ip_summed = CHECKSUM_NONE;
1586
1587                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1588                 if (len <= 0) {
1589                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1590                         goto err;
1591                 }
1592                 len += 2;
1593                 if (len > skb->len)
1594                         skb_put(skb, len - skb->len);
1595                 else if (len < skb->len)
1596                         skb_trim(skb, len);
1597                 proto = PPP_IP;
1598                 break;
1599
1600         case PPP_VJC_UNCOMP:
1601                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1602                         goto err;
1603
1604                 /* Until we fix the decompressor need to make sure
1605                  * data portion is linear.
1606                  */
1607                 if (!pskb_may_pull(skb, skb->len))
1608                         goto err;
1609
1610                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1611                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1612                         goto err;
1613                 }
1614                 proto = PPP_IP;
1615                 break;
1616
1617         case PPP_CCP:
1618                 ppp_ccp_peek(ppp, skb, 1);
1619                 break;
1620         }
1621
1622         ++ppp->dev->stats.rx_packets;
1623         ppp->dev->stats.rx_bytes += skb->len - 2;
1624
1625         npi = proto_to_npindex(proto);
1626         if (npi < 0) {
1627                 /* control or unknown frame - pass it to pppd */
1628                 skb_queue_tail(&ppp->file.rq, skb);
1629                 /* limit queue length by dropping old frames */
1630                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1631                        && (skb = skb_dequeue(&ppp->file.rq)))
1632                         kfree_skb(skb);
1633                 /* wake up any process polling or blocking on read */
1634                 wake_up_interruptible(&ppp->file.rwait);
1635
1636         } else {
1637                 /* network protocol frame - give it to the kernel */
1638
1639 #ifdef CONFIG_PPP_FILTER
1640                 /* check if the packet passes the pass and active filters */
1641                 /* the filter instructions are constructed assuming
1642                    a four-byte PPP header on each packet */
1643                 if (ppp->pass_filter || ppp->active_filter) {
1644                         if (skb_cloned(skb) &&
1645                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
1646                                 goto err;
1647
1648                         *skb_push(skb, 2) = 0;
1649                         if (ppp->pass_filter
1650                             && sk_run_filter(skb, ppp->pass_filter,
1651                                              ppp->pass_len) == 0) {
1652                                 if (ppp->debug & 1)
1653                                         printk(KERN_DEBUG "PPP: inbound frame "
1654                                                "not passed\n");
1655                                 kfree_skb(skb);
1656                                 return;
1657                         }
1658                         if (!(ppp->active_filter
1659                               && sk_run_filter(skb, ppp->active_filter,
1660                                                ppp->active_len) == 0))
1661                                 ppp->last_recv = jiffies;
1662                         __skb_pull(skb, 2);
1663                 } else
1664 #endif /* CONFIG_PPP_FILTER */
1665                         ppp->last_recv = jiffies;
1666
1667                 if ((ppp->dev->flags & IFF_UP) == 0
1668                     || ppp->npmode[npi] != NPMODE_PASS) {
1669                         kfree_skb(skb);
1670                 } else {
1671                         /* chop off protocol */
1672                         skb_pull_rcsum(skb, 2);
1673                         skb->dev = ppp->dev;
1674                         skb->protocol = htons(npindex_to_ethertype[npi]);
1675                         skb_reset_mac_header(skb);
1676                         netif_rx(skb);
1677                         ppp->dev->last_rx = jiffies;
1678                 }
1679         }
1680         return;
1681
1682  err:
1683         kfree_skb(skb);
1684         ppp_receive_error(ppp);
1685 }
1686
1687 static struct sk_buff *
1688 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1689 {
1690         int proto = PPP_PROTO(skb);
1691         struct sk_buff *ns;
1692         int len;
1693
1694         /* Until we fix all the decompressor's need to make sure
1695          * data portion is linear.
1696          */
1697         if (!pskb_may_pull(skb, skb->len))
1698                 goto err;
1699
1700         if (proto == PPP_COMP) {
1701                 int obuff_size;
1702
1703                 switch(ppp->rcomp->compress_proto) {
1704                 case CI_MPPE:
1705                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1706                         break;
1707                 default:
1708                         obuff_size = ppp->mru + PPP_HDRLEN;
1709                         break;
1710                 }
1711
1712                 ns = dev_alloc_skb(obuff_size);
1713                 if (!ns) {
1714                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1715                         goto err;
1716                 }
1717                 /* the decompressor still expects the A/C bytes in the hdr */
1718                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1719                                 skb->len + 2, ns->data, obuff_size);
1720                 if (len < 0) {
1721                         /* Pass the compressed frame to pppd as an
1722                            error indication. */
1723                         if (len == DECOMP_FATALERROR)
1724                                 ppp->rstate |= SC_DC_FERROR;
1725                         kfree_skb(ns);
1726                         goto err;
1727                 }
1728
1729                 kfree_skb(skb);
1730                 skb = ns;
1731                 skb_put(skb, len);
1732                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1733
1734         } else {
1735                 /* Uncompressed frame - pass to decompressor so it
1736                    can update its dictionary if necessary. */
1737                 if (ppp->rcomp->incomp)
1738                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1739                                            skb->len + 2);
1740         }
1741
1742         return skb;
1743
1744  err:
1745         ppp->rstate |= SC_DC_ERROR;
1746         ppp_receive_error(ppp);
1747         return skb;
1748 }
1749
1750 #ifdef CONFIG_PPP_MULTILINK
1751 /*
1752  * Receive a multilink frame.
1753  * We put it on the reconstruction queue and then pull off
1754  * as many completed frames as we can.
1755  */
1756 static void
1757 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1758 {
1759         u32 mask, seq;
1760         struct channel *ch;
1761         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1762
1763         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1764                 goto err;               /* no good, throw it away */
1765
1766         /* Decode sequence number and begin/end bits */
1767         if (ppp->flags & SC_MP_SHORTSEQ) {
1768                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1769                 mask = 0xfff;
1770         } else {
1771                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1772                 mask = 0xffffff;
1773         }
1774         skb->BEbits = skb->data[2];
1775         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1776
1777         /*
1778          * Do protocol ID decompression on the first fragment of each packet.
1779          */
1780         if ((skb->BEbits & B) && (skb->data[0] & 1))
1781                 *skb_push(skb, 1) = 0;
1782
1783         /*
1784          * Expand sequence number to 32 bits, making it as close
1785          * as possible to ppp->minseq.
1786          */
1787         seq |= ppp->minseq & ~mask;
1788         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1789                 seq += mask + 1;
1790         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1791                 seq -= mask + 1;        /* should never happen */
1792         skb->sequence = seq;
1793         pch->lastseq = seq;
1794
1795         /*
1796          * If this packet comes before the next one we were expecting,
1797          * drop it.
1798          */
1799         if (seq_before(seq, ppp->nextseq)) {
1800                 kfree_skb(skb);
1801                 ++ppp->dev->stats.rx_dropped;
1802                 ppp_receive_error(ppp);
1803                 return;
1804         }
1805
1806         /*
1807          * Reevaluate minseq, the minimum over all channels of the
1808          * last sequence number received on each channel.  Because of
1809          * the increasing sequence number rule, we know that any fragment
1810          * before `minseq' which hasn't arrived is never going to arrive.
1811          * The list of channels can't change because we have the receive
1812          * side of the ppp unit locked.
1813          */
1814         list_for_each_entry(ch, &ppp->channels, clist) {
1815                 if (seq_before(ch->lastseq, seq))
1816                         seq = ch->lastseq;
1817         }
1818         if (seq_before(ppp->minseq, seq))
1819                 ppp->minseq = seq;
1820
1821         /* Put the fragment on the reconstruction queue */
1822         ppp_mp_insert(ppp, skb);
1823
1824         /* If the queue is getting long, don't wait any longer for packets
1825            before the start of the queue. */
1826         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN
1827             && seq_before(ppp->minseq, ppp->mrq.next->sequence))
1828                 ppp->minseq = ppp->mrq.next->sequence;
1829
1830         /* Pull completed packets off the queue and receive them. */
1831         while ((skb = ppp_mp_reconstruct(ppp)))
1832                 ppp_receive_nonmp_frame(ppp, skb);
1833
1834         return;
1835
1836  err:
1837         kfree_skb(skb);
1838         ppp_receive_error(ppp);
1839 }
1840
1841 /*
1842  * Insert a fragment on the MP reconstruction queue.
1843  * The queue is ordered by increasing sequence number.
1844  */
1845 static void
1846 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1847 {
1848         struct sk_buff *p;
1849         struct sk_buff_head *list = &ppp->mrq;
1850         u32 seq = skb->sequence;
1851
1852         /* N.B. we don't need to lock the list lock because we have the
1853            ppp unit receive-side lock. */
1854         for (p = list->next; p != (struct sk_buff *)list; p = p->next)
1855                 if (seq_before(seq, p->sequence))
1856                         break;
1857         __skb_insert(skb, p->prev, p, list);
1858 }
1859
1860 /*
1861  * Reconstruct a packet from the MP fragment queue.
1862  * We go through increasing sequence numbers until we find a
1863  * complete packet, or we get to the sequence number for a fragment
1864  * which hasn't arrived but might still do so.
1865  */
1866 static struct sk_buff *
1867 ppp_mp_reconstruct(struct ppp *ppp)
1868 {
1869         u32 seq = ppp->nextseq;
1870         u32 minseq = ppp->minseq;
1871         struct sk_buff_head *list = &ppp->mrq;
1872         struct sk_buff *p, *next;
1873         struct sk_buff *head, *tail;
1874         struct sk_buff *skb = NULL;
1875         int lost = 0, len = 0;
1876
1877         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1878                 return NULL;
1879         head = list->next;
1880         tail = NULL;
1881         for (p = head; p != (struct sk_buff *) list; p = next) {
1882                 next = p->next;
1883                 if (seq_before(p->sequence, seq)) {
1884                         /* this can't happen, anyway ignore the skb */
1885                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1886                                p->sequence, seq);
1887                         head = next;
1888                         continue;
1889                 }
1890                 if (p->sequence != seq) {
1891                         /* Fragment `seq' is missing.  If it is after
1892                            minseq, it might arrive later, so stop here. */
1893                         if (seq_after(seq, minseq))
1894                                 break;
1895                         /* Fragment `seq' is lost, keep going. */
1896                         lost = 1;
1897                         seq = seq_before(minseq, p->sequence)?
1898                                 minseq + 1: p->sequence;
1899                         next = p;
1900                         continue;
1901                 }
1902
1903                 /*
1904                  * At this point we know that all the fragments from
1905                  * ppp->nextseq to seq are either present or lost.
1906                  * Also, there are no complete packets in the queue
1907                  * that have no missing fragments and end before this
1908                  * fragment.
1909                  */
1910
1911                 /* B bit set indicates this fragment starts a packet */
1912                 if (p->BEbits & B) {
1913                         head = p;
1914                         lost = 0;
1915                         len = 0;
1916                 }
1917
1918                 len += p->len;
1919
1920                 /* Got a complete packet yet? */
1921                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1922                         if (len > ppp->mrru + 2) {
1923                                 ++ppp->dev->stats.rx_length_errors;
1924                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1925                                        " is too long (%d)\n", len);
1926                         } else if (p == head) {
1927                                 /* fragment is complete packet - reuse skb */
1928                                 tail = p;
1929                                 skb = skb_get(p);
1930                                 break;
1931                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1932                                 ++ppp->dev->stats.rx_missed_errors;
1933                                 printk(KERN_DEBUG "PPP: no memory for "
1934                                        "reconstructed packet");
1935                         } else {
1936                                 tail = p;
1937                                 break;
1938                         }
1939                         ppp->nextseq = seq + 1;
1940                 }
1941
1942                 /*
1943                  * If this is the ending fragment of a packet,
1944                  * and we haven't found a complete valid packet yet,
1945                  * we can discard up to and including this fragment.
1946                  */
1947                 if (p->BEbits & E)
1948                         head = next;
1949
1950                 ++seq;
1951         }
1952
1953         /* If we have a complete packet, copy it all into one skb. */
1954         if (tail != NULL) {
1955                 /* If we have discarded any fragments,
1956                    signal a receive error. */
1957                 if (head->sequence != ppp->nextseq) {
1958                         if (ppp->debug & 1)
1959                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1960                                        ppp->nextseq, head->sequence-1);
1961                         ++ppp->dev->stats.rx_dropped;
1962                         ppp_receive_error(ppp);
1963                 }
1964
1965                 if (head != tail)
1966                         /* copy to a single skb */
1967                         for (p = head; p != tail->next; p = p->next)
1968                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1969                 ppp->nextseq = tail->sequence + 1;
1970                 head = tail->next;
1971         }
1972
1973         /* Discard all the skbuffs that we have copied the data out of
1974            or that we can't use. */
1975         while ((p = list->next) != head) {
1976                 __skb_unlink(p, list);
1977                 kfree_skb(p);
1978         }
1979
1980         return skb;
1981 }
1982 #endif /* CONFIG_PPP_MULTILINK */
1983
1984 /*
1985  * Channel interface.
1986  */
1987
1988 /*
1989  * Create a new, unattached ppp channel.
1990  */
1991 int
1992 ppp_register_channel(struct ppp_channel *chan)
1993 {
1994         struct channel *pch;
1995
1996         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
1997         if (!pch)
1998                 return -ENOMEM;
1999         pch->ppp = NULL;
2000         pch->chan = chan;
2001         chan->ppp = pch;
2002         init_ppp_file(&pch->file, CHANNEL);
2003         pch->file.hdrlen = chan->hdrlen;
2004 #ifdef CONFIG_PPP_MULTILINK
2005         pch->lastseq = -1;
2006 #endif /* CONFIG_PPP_MULTILINK */
2007         init_rwsem(&pch->chan_sem);
2008         spin_lock_init(&pch->downl);
2009         rwlock_init(&pch->upl);
2010         spin_lock_bh(&all_channels_lock);
2011         pch->file.index = ++last_channel_index;
2012         list_add(&pch->list, &new_channels);
2013         atomic_inc(&channel_count);
2014         spin_unlock_bh(&all_channels_lock);
2015         return 0;
2016 }
2017
2018 /*
2019  * Return the index of a channel.
2020  */
2021 int ppp_channel_index(struct ppp_channel *chan)
2022 {
2023         struct channel *pch = chan->ppp;
2024
2025         if (pch)
2026                 return pch->file.index;
2027         return -1;
2028 }
2029
2030 /*
2031  * Return the PPP unit number to which a channel is connected.
2032  */
2033 int ppp_unit_number(struct ppp_channel *chan)
2034 {
2035         struct channel *pch = chan->ppp;
2036         int unit = -1;
2037
2038         if (pch) {
2039                 read_lock_bh(&pch->upl);
2040                 if (pch->ppp)
2041                         unit = pch->ppp->file.index;
2042                 read_unlock_bh(&pch->upl);
2043         }
2044         return unit;
2045 }
2046
2047 /*
2048  * Disconnect a channel from the generic layer.
2049  * This must be called in process context.
2050  */
2051 void
2052 ppp_unregister_channel(struct ppp_channel *chan)
2053 {
2054         struct channel *pch = chan->ppp;
2055
2056         if (!pch)
2057                 return;         /* should never happen */
2058         chan->ppp = NULL;
2059
2060         /*
2061          * This ensures that we have returned from any calls into the
2062          * the channel's start_xmit or ioctl routine before we proceed.
2063          */
2064         down_write(&pch->chan_sem);
2065         spin_lock_bh(&pch->downl);
2066         pch->chan = NULL;
2067         spin_unlock_bh(&pch->downl);
2068         up_write(&pch->chan_sem);
2069         ppp_disconnect_channel(pch);
2070         spin_lock_bh(&all_channels_lock);
2071         list_del(&pch->list);
2072         spin_unlock_bh(&all_channels_lock);
2073         pch->file.dead = 1;
2074         wake_up_interruptible(&pch->file.rwait);
2075         if (atomic_dec_and_test(&pch->file.refcnt))
2076                 ppp_destroy_channel(pch);
2077 }
2078
2079 /*
2080  * Callback from a channel when it can accept more to transmit.
2081  * This should be called at BH/softirq level, not interrupt level.
2082  */
2083 void
2084 ppp_output_wakeup(struct ppp_channel *chan)
2085 {
2086         struct channel *pch = chan->ppp;
2087
2088         if (!pch)
2089                 return;
2090         ppp_channel_push(pch);
2091 }
2092
2093 /*
2094  * Compression control.
2095  */
2096
2097 /* Process the PPPIOCSCOMPRESS ioctl. */
2098 static int
2099 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2100 {
2101         int err;
2102         struct compressor *cp, *ocomp;
2103         struct ppp_option_data data;
2104         void *state, *ostate;
2105         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2106
2107         err = -EFAULT;
2108         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2109             || (data.length <= CCP_MAX_OPTION_LENGTH
2110                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2111                 goto out;
2112         err = -EINVAL;
2113         if (data.length > CCP_MAX_OPTION_LENGTH
2114             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2115                 goto out;
2116
2117         cp = find_compressor(ccp_option[0]);
2118 #ifdef CONFIG_KMOD
2119         if (!cp) {
2120                 request_module("ppp-compress-%d", ccp_option[0]);
2121                 cp = find_compressor(ccp_option[0]);
2122         }
2123 #endif /* CONFIG_KMOD */
2124         if (!cp)
2125                 goto out;
2126
2127         err = -ENOBUFS;
2128         if (data.transmit) {
2129                 state = cp->comp_alloc(ccp_option, data.length);
2130                 if (state) {
2131                         ppp_xmit_lock(ppp);
2132                         ppp->xstate &= ~SC_COMP_RUN;
2133                         ocomp = ppp->xcomp;
2134                         ostate = ppp->xc_state;
2135                         ppp->xcomp = cp;
2136                         ppp->xc_state = state;
2137                         ppp_xmit_unlock(ppp);
2138                         if (ostate) {
2139                                 ocomp->comp_free(ostate);
2140                                 module_put(ocomp->owner);
2141                         }
2142                         err = 0;
2143                 } else
2144                         module_put(cp->owner);
2145
2146         } else {
2147                 state = cp->decomp_alloc(ccp_option, data.length);
2148                 if (state) {
2149                         ppp_recv_lock(ppp);
2150                         ppp->rstate &= ~SC_DECOMP_RUN;
2151                         ocomp = ppp->rcomp;
2152                         ostate = ppp->rc_state;
2153                         ppp->rcomp = cp;
2154                         ppp->rc_state = state;
2155                         ppp_recv_unlock(ppp);
2156                         if (ostate) {
2157                                 ocomp->decomp_free(ostate);
2158                                 module_put(ocomp->owner);
2159                         }
2160                         err = 0;
2161                 } else
2162                         module_put(cp->owner);
2163         }
2164
2165  out:
2166         return err;
2167 }
2168
2169 /*
2170  * Look at a CCP packet and update our state accordingly.
2171  * We assume the caller has the xmit or recv path locked.
2172  */
2173 static void
2174 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2175 {
2176         unsigned char *dp;
2177         int len;
2178
2179         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2180                 return; /* no header */
2181         dp = skb->data + 2;
2182
2183         switch (CCP_CODE(dp)) {
2184         case CCP_CONFREQ:
2185
2186                 /* A ConfReq starts negotiation of compression
2187                  * in one direction of transmission,
2188                  * and hence brings it down...but which way?
2189                  *
2190                  * Remember:
2191                  * A ConfReq indicates what the sender would like to receive
2192                  */
2193                 if(inbound)
2194                         /* He is proposing what I should send */
2195                         ppp->xstate &= ~SC_COMP_RUN;
2196                 else
2197                         /* I am proposing to what he should send */
2198                         ppp->rstate &= ~SC_DECOMP_RUN;
2199
2200                 break;
2201
2202         case CCP_TERMREQ:
2203         case CCP_TERMACK:
2204                 /*
2205                  * CCP is going down, both directions of transmission
2206                  */
2207                 ppp->rstate &= ~SC_DECOMP_RUN;
2208                 ppp->xstate &= ~SC_COMP_RUN;
2209                 break;
2210
2211         case CCP_CONFACK:
2212                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2213                         break;
2214                 len = CCP_LENGTH(dp);
2215                 if (!pskb_may_pull(skb, len + 2))
2216                         return;         /* too short */
2217                 dp += CCP_HDRLEN;
2218                 len -= CCP_HDRLEN;
2219                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2220                         break;
2221                 if (inbound) {
2222                         /* we will start receiving compressed packets */
2223                         if (!ppp->rc_state)
2224                                 break;
2225                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2226                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2227                                 ppp->rstate |= SC_DECOMP_RUN;
2228                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2229                         }
2230                 } else {
2231                         /* we will soon start sending compressed packets */
2232                         if (!ppp->xc_state)
2233                                 break;
2234                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2235                                         ppp->file.index, 0, ppp->debug))
2236                                 ppp->xstate |= SC_COMP_RUN;
2237                 }
2238                 break;
2239
2240         case CCP_RESETACK:
2241                 /* reset the [de]compressor */
2242                 if ((ppp->flags & SC_CCP_UP) == 0)
2243                         break;
2244                 if (inbound) {
2245                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2246                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2247                                 ppp->rstate &= ~SC_DC_ERROR;
2248                         }
2249                 } else {
2250                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2251                                 ppp->xcomp->comp_reset(ppp->xc_state);
2252                 }
2253                 break;
2254         }
2255 }
2256
2257 /* Free up compression resources. */
2258 static void
2259 ppp_ccp_closed(struct ppp *ppp)
2260 {
2261         void *xstate, *rstate;
2262         struct compressor *xcomp, *rcomp;
2263
2264         ppp_lock(ppp);
2265         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2266         ppp->xstate = 0;
2267         xcomp = ppp->xcomp;
2268         xstate = ppp->xc_state;
2269         ppp->xc_state = NULL;
2270         ppp->rstate = 0;
2271         rcomp = ppp->rcomp;
2272         rstate = ppp->rc_state;
2273         ppp->rc_state = NULL;
2274         ppp_unlock(ppp);
2275
2276         if (xstate) {
2277                 xcomp->comp_free(xstate);
2278                 module_put(xcomp->owner);
2279         }
2280         if (rstate) {
2281                 rcomp->decomp_free(rstate);
2282                 module_put(rcomp->owner);
2283         }
2284 }
2285
2286 /* List of compressors. */
2287 static LIST_HEAD(compressor_list);
2288 static DEFINE_SPINLOCK(compressor_list_lock);
2289
2290 struct compressor_entry {
2291         struct list_head list;
2292         struct compressor *comp;
2293 };
2294
2295 static struct compressor_entry *
2296 find_comp_entry(int proto)
2297 {
2298         struct compressor_entry *ce;
2299
2300         list_for_each_entry(ce, &compressor_list, list) {
2301                 if (ce->comp->compress_proto == proto)
2302                         return ce;
2303         }
2304         return NULL;
2305 }
2306
2307 /* Register a compressor */
2308 int
2309 ppp_register_compressor(struct compressor *cp)
2310 {
2311         struct compressor_entry *ce;
2312         int ret;
2313         spin_lock(&compressor_list_lock);
2314         ret = -EEXIST;
2315         if (find_comp_entry(cp->compress_proto))
2316                 goto out;
2317         ret = -ENOMEM;
2318         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2319         if (!ce)
2320                 goto out;
2321         ret = 0;
2322         ce->comp = cp;
2323         list_add(&ce->list, &compressor_list);
2324  out:
2325         spin_unlock(&compressor_list_lock);
2326         return ret;
2327 }
2328
2329 /* Unregister a compressor */
2330 void
2331 ppp_unregister_compressor(struct compressor *cp)
2332 {
2333         struct compressor_entry *ce;
2334
2335         spin_lock(&compressor_list_lock);
2336         ce = find_comp_entry(cp->compress_proto);
2337         if (ce && ce->comp == cp) {
2338                 list_del(&ce->list);
2339                 kfree(ce);
2340         }
2341         spin_unlock(&compressor_list_lock);
2342 }
2343
2344 /* Find a compressor. */
2345 static struct compressor *
2346 find_compressor(int type)
2347 {
2348         struct compressor_entry *ce;
2349         struct compressor *cp = NULL;
2350
2351         spin_lock(&compressor_list_lock);
2352         ce = find_comp_entry(type);
2353         if (ce) {
2354                 cp = ce->comp;
2355                 if (!try_module_get(cp->owner))
2356                         cp = NULL;
2357         }
2358         spin_unlock(&compressor_list_lock);
2359         return cp;
2360 }
2361
2362 /*
2363  * Miscelleneous stuff.
2364  */
2365
2366 static void
2367 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2368 {
2369         struct slcompress *vj = ppp->vj;
2370
2371         memset(st, 0, sizeof(*st));
2372         st->p.ppp_ipackets = ppp->dev->stats.rx_packets;
2373         st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2374         st->p.ppp_ibytes = ppp->dev->stats.rx_bytes;
2375         st->p.ppp_opackets = ppp->dev->stats.tx_packets;
2376         st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2377         st->p.ppp_obytes = ppp->dev->stats.tx_bytes;
2378         if (!vj)
2379                 return;
2380         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2381         st->vj.vjs_compressed = vj->sls_o_compressed;
2382         st->vj.vjs_searches = vj->sls_o_searches;
2383         st->vj.vjs_misses = vj->sls_o_misses;
2384         st->vj.vjs_errorin = vj->sls_i_error;
2385         st->vj.vjs_tossed = vj->sls_i_tossed;
2386         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2387         st->vj.vjs_compressedin = vj->sls_i_compressed;
2388 }
2389
2390 /*
2391  * Stuff for handling the lists of ppp units and channels
2392  * and for initialization.
2393  */
2394
2395 /*
2396  * Create a new ppp interface unit.  Fails if it can't allocate memory
2397  * or if there is already a unit with the requested number.
2398  * unit == -1 means allocate a new number.
2399  */
2400 static struct ppp *
2401 ppp_create_interface(int unit, int *retp)
2402 {
2403         struct ppp *ppp;
2404         struct net_device *dev = NULL;
2405         int ret = -ENOMEM;
2406         int i;
2407
2408         ppp = kzalloc(sizeof(struct ppp), GFP_KERNEL);
2409         if (!ppp)
2410                 goto out;
2411         dev = alloc_netdev(0, "", ppp_setup);
2412         if (!dev)
2413                 goto out1;
2414
2415         ppp->mru = PPP_MRU;
2416         init_ppp_file(&ppp->file, INTERFACE);
2417         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2418         for (i = 0; i < NUM_NP; ++i)
2419                 ppp->npmode[i] = NPMODE_PASS;
2420         INIT_LIST_HEAD(&ppp->channels);
2421         spin_lock_init(&ppp->rlock);
2422         spin_lock_init(&ppp->wlock);
2423 #ifdef CONFIG_PPP_MULTILINK
2424         ppp->minseq = -1;
2425         skb_queue_head_init(&ppp->mrq);
2426 #endif /* CONFIG_PPP_MULTILINK */
2427         ppp->dev = dev;
2428         dev->priv = ppp;
2429
2430         dev->hard_start_xmit = ppp_start_xmit;
2431         dev->do_ioctl = ppp_net_ioctl;
2432
2433         ret = -EEXIST;
2434         mutex_lock(&all_ppp_mutex);
2435         if (unit < 0)
2436                 unit = cardmap_find_first_free(all_ppp_units);
2437         else if (cardmap_get(all_ppp_units, unit) != NULL)
2438                 goto out2;      /* unit already exists */
2439
2440         /* Initialize the new ppp unit */
2441         ppp->file.index = unit;
2442         sprintf(dev->name, "ppp%d", unit);
2443
2444         ret = register_netdev(dev);
2445         if (ret != 0) {
2446                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2447                        dev->name, ret);
2448                 goto out2;
2449         }
2450
2451         atomic_inc(&ppp_unit_count);
2452         ret = cardmap_set(&all_ppp_units, unit, ppp);
2453         if (ret != 0)
2454                 goto out3;
2455
2456         mutex_unlock(&all_ppp_mutex);
2457         *retp = 0;
2458         return ppp;
2459
2460 out3:
2461         atomic_dec(&ppp_unit_count);
2462         unregister_netdev(dev);
2463 out2:
2464         mutex_unlock(&all_ppp_mutex);
2465         free_netdev(dev);
2466 out1:
2467         kfree(ppp);
2468 out:
2469         *retp = ret;
2470         return NULL;
2471 }
2472
2473 /*
2474  * Initialize a ppp_file structure.
2475  */
2476 static void
2477 init_ppp_file(struct ppp_file *pf, int kind)
2478 {
2479         pf->kind = kind;
2480         skb_queue_head_init(&pf->xq);
2481         skb_queue_head_init(&pf->rq);
2482         atomic_set(&pf->refcnt, 1);
2483         init_waitqueue_head(&pf->rwait);
2484 }
2485
2486 /*
2487  * Take down a ppp interface unit - called when the owning file
2488  * (the one that created the unit) is closed or detached.
2489  */
2490 static void ppp_shutdown_interface(struct ppp *ppp)
2491 {
2492         struct net_device *dev;
2493
2494         mutex_lock(&all_ppp_mutex);
2495         ppp_lock(ppp);
2496         dev = ppp->dev;
2497         ppp->dev = NULL;
2498         ppp_unlock(ppp);
2499         /* This will call dev_close() for us. */
2500         if (dev) {
2501                 unregister_netdev(dev);
2502                 free_netdev(dev);
2503         }
2504         cardmap_set(&all_ppp_units, ppp->file.index, NULL);
2505         ppp->file.dead = 1;
2506         ppp->owner = NULL;
2507         wake_up_interruptible(&ppp->file.rwait);
2508         mutex_unlock(&all_ppp_mutex);
2509 }
2510
2511 /*
2512  * Free the memory used by a ppp unit.  This is only called once
2513  * there are no channels connected to the unit and no file structs
2514  * that reference the unit.
2515  */
2516 static void ppp_destroy_interface(struct ppp *ppp)
2517 {
2518         atomic_dec(&ppp_unit_count);
2519
2520         if (!ppp->file.dead || ppp->n_channels) {
2521                 /* "can't happen" */
2522                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2523                        "n_channels=%d !\n", ppp, ppp->file.dead,
2524                        ppp->n_channels);
2525                 return;
2526         }
2527
2528         ppp_ccp_closed(ppp);
2529         if (ppp->vj) {
2530                 slhc_free(ppp->vj);
2531                 ppp->vj = NULL;
2532         }
2533         skb_queue_purge(&ppp->file.xq);
2534         skb_queue_purge(&ppp->file.rq);
2535 #ifdef CONFIG_PPP_MULTILINK
2536         skb_queue_purge(&ppp->mrq);
2537 #endif /* CONFIG_PPP_MULTILINK */
2538 #ifdef CONFIG_PPP_FILTER
2539         kfree(ppp->pass_filter);
2540         ppp->pass_filter = NULL;
2541         kfree(ppp->active_filter);
2542         ppp->active_filter = NULL;
2543 #endif /* CONFIG_PPP_FILTER */
2544
2545         if (ppp->xmit_pending)
2546                 kfree_skb(ppp->xmit_pending);
2547
2548         kfree(ppp);
2549 }
2550
2551 /*
2552  * Locate an existing ppp unit.
2553  * The caller should have locked the all_ppp_mutex.
2554  */
2555 static struct ppp *
2556 ppp_find_unit(int unit)
2557 {
2558         return cardmap_get(all_ppp_units, unit);
2559 }
2560
2561 /*
2562  * Locate an existing ppp channel.
2563  * The caller should have locked the all_channels_lock.
2564  * First we look in the new_channels list, then in the
2565  * all_channels list.  If found in the new_channels list,
2566  * we move it to the all_channels list.  This is for speed
2567  * when we have a lot of channels in use.
2568  */
2569 static struct channel *
2570 ppp_find_channel(int unit)
2571 {
2572         struct channel *pch;
2573
2574         list_for_each_entry(pch, &new_channels, list) {
2575                 if (pch->file.index == unit) {
2576                         list_move(&pch->list, &all_channels);
2577                         return pch;
2578                 }
2579         }
2580         list_for_each_entry(pch, &all_channels, list) {
2581                 if (pch->file.index == unit)
2582                         return pch;
2583         }
2584         return NULL;
2585 }
2586
2587 /*
2588  * Connect a PPP channel to a PPP interface unit.
2589  */
2590 static int
2591 ppp_connect_channel(struct channel *pch, int unit)
2592 {
2593         struct ppp *ppp;
2594         int ret = -ENXIO;
2595         int hdrlen;
2596
2597         mutex_lock(&all_ppp_mutex);
2598         ppp = ppp_find_unit(unit);
2599         if (!ppp)
2600                 goto out;
2601         write_lock_bh(&pch->upl);
2602         ret = -EINVAL;
2603         if (pch->ppp)
2604                 goto outl;
2605
2606         ppp_lock(ppp);
2607         if (pch->file.hdrlen > ppp->file.hdrlen)
2608                 ppp->file.hdrlen = pch->file.hdrlen;
2609         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2610         if (ppp->dev && hdrlen > ppp->dev->hard_header_len)
2611                 ppp->dev->hard_header_len = hdrlen;
2612         list_add_tail(&pch->clist, &ppp->channels);
2613         ++ppp->n_channels;
2614         pch->ppp = ppp;
2615         atomic_inc(&ppp->file.refcnt);
2616         ppp_unlock(ppp);
2617         ret = 0;
2618
2619  outl:
2620         write_unlock_bh(&pch->upl);
2621  out:
2622         mutex_unlock(&all_ppp_mutex);
2623         return ret;
2624 }
2625
2626 /*
2627  * Disconnect a channel from its ppp unit.
2628  */
2629 static int
2630 ppp_disconnect_channel(struct channel *pch)
2631 {
2632         struct ppp *ppp;
2633         int err = -EINVAL;
2634
2635         write_lock_bh(&pch->upl);
2636         ppp = pch->ppp;
2637         pch->ppp = NULL;
2638         write_unlock_bh(&pch->upl);
2639         if (ppp) {
2640                 /* remove it from the ppp unit's list */
2641                 ppp_lock(ppp);
2642                 list_del(&pch->clist);
2643                 if (--ppp->n_channels == 0)
2644                         wake_up_interruptible(&ppp->file.rwait);
2645                 ppp_unlock(ppp);
2646                 if (atomic_dec_and_test(&ppp->file.refcnt))
2647                         ppp_destroy_interface(ppp);
2648                 err = 0;
2649         }
2650         return err;
2651 }
2652
2653 /*
2654  * Free up the resources used by a ppp channel.
2655  */
2656 static void ppp_destroy_channel(struct channel *pch)
2657 {
2658         atomic_dec(&channel_count);
2659
2660         if (!pch->file.dead) {
2661                 /* "can't happen" */
2662                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2663                        pch);
2664                 return;
2665         }
2666         skb_queue_purge(&pch->file.xq);
2667         skb_queue_purge(&pch->file.rq);
2668         kfree(pch);
2669 }
2670
2671 static void __exit ppp_cleanup(void)
2672 {
2673         /* should never happen */
2674         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2675                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2676         cardmap_destroy(&all_ppp_units);
2677         unregister_chrdev(PPP_MAJOR, "ppp");
2678         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2679         class_destroy(ppp_class);
2680 }
2681
2682 /*
2683  * Cardmap implementation.
2684  */
2685 static void *cardmap_get(struct cardmap *map, unsigned int nr)
2686 {
2687         struct cardmap *p;
2688         int i;
2689
2690         for (p = map; p != NULL; ) {
2691                 if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
2692                         return NULL;
2693                 if (p->shift == 0)
2694                         return p->ptr[i];
2695                 nr &= ~(CARDMAP_MASK << p->shift);
2696                 p = p->ptr[i];
2697         }
2698         return NULL;
2699 }
2700
2701 static int cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
2702 {
2703         struct cardmap *p;
2704         int i;
2705
2706         p = *pmap;
2707         if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
2708                 do {
2709                         /* need a new top level */
2710                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2711                         if (!np)
2712                                 goto enomem;
2713                         np->ptr[0] = p;
2714                         if (p != NULL) {
2715                                 np->shift = p->shift + CARDMAP_ORDER;
2716                                 p->parent = np;
2717                         } else
2718                                 np->shift = 0;
2719                         p = np;
2720                 } while ((nr >> p->shift) >= CARDMAP_WIDTH);
2721                 *pmap = p;
2722         }
2723         while (p->shift > 0) {
2724                 i = (nr >> p->shift) & CARDMAP_MASK;
2725                 if (p->ptr[i] == NULL) {
2726                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2727                         if (!np)
2728                                 goto enomem;
2729                         np->shift = p->shift - CARDMAP_ORDER;
2730                         np->parent = p;
2731                         p->ptr[i] = np;
2732                 }
2733                 if (ptr == NULL)
2734                         clear_bit(i, &p->inuse);
2735                 p = p->ptr[i];
2736         }
2737         i = nr & CARDMAP_MASK;
2738         p->ptr[i] = ptr;
2739         if (ptr != NULL)
2740                 set_bit(i, &p->inuse);
2741         else
2742                 clear_bit(i, &p->inuse);
2743         return 0;
2744  enomem:
2745         return -ENOMEM;
2746 }
2747
2748 static unsigned int cardmap_find_first_free(struct cardmap *map)
2749 {
2750         struct cardmap *p;
2751         unsigned int nr = 0;
2752         int i;
2753
2754         if ((p = map) == NULL)
2755                 return 0;
2756         for (;;) {
2757                 i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
2758                 if (i >= CARDMAP_WIDTH) {
2759                         if (p->parent == NULL)
2760                                 return CARDMAP_WIDTH << p->shift;
2761                         p = p->parent;
2762                         i = (nr >> p->shift) & CARDMAP_MASK;
2763                         set_bit(i, &p->inuse);
2764                         continue;
2765                 }
2766                 nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
2767                 if (p->shift == 0 || p->ptr[i] == NULL)
2768                         return nr;
2769                 p = p->ptr[i];
2770         }
2771 }
2772
2773 static void cardmap_destroy(struct cardmap **pmap)
2774 {
2775         struct cardmap *p, *np;
2776         int i;
2777
2778         for (p = *pmap; p != NULL; p = np) {
2779                 if (p->shift != 0) {
2780                         for (i = 0; i < CARDMAP_WIDTH; ++i)
2781                                 if (p->ptr[i] != NULL)
2782                                         break;
2783                         if (i < CARDMAP_WIDTH) {
2784                                 np = p->ptr[i];
2785                                 p->ptr[i] = NULL;
2786                                 continue;
2787                         }
2788                 }
2789                 np = p->parent;
2790                 kfree(p);
2791         }
2792         *pmap = NULL;
2793 }
2794
2795 /* Module/initialization stuff */
2796
2797 module_init(ppp_init);
2798 module_exit(ppp_cleanup);
2799
2800 EXPORT_SYMBOL(ppp_register_channel);
2801 EXPORT_SYMBOL(ppp_unregister_channel);
2802 EXPORT_SYMBOL(ppp_channel_index);
2803 EXPORT_SYMBOL(ppp_unit_number);
2804 EXPORT_SYMBOL(ppp_input);
2805 EXPORT_SYMBOL(ppp_input_error);
2806 EXPORT_SYMBOL(ppp_output_wakeup);
2807 EXPORT_SYMBOL(ppp_register_compressor);
2808 EXPORT_SYMBOL(ppp_unregister_compressor);
2809 MODULE_LICENSE("GPL");
2810 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2811 MODULE_ALIAS("/dev/ppp");