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 static int ppp_open(struct inode *inode, struct file *file)
 355 {
 356         /*
 357          * This could (should?) be enforced by the permissions on /dev/ppp.
 358          */
 359         if (!capable(CAP_NET_ADMIN))
 360                 return -EPERM;
 361         return 0;
 362 }
 363
 364 static int ppp_release(struct inode *unused, struct file *file)
 365 {
 366         struct ppp_file *pf = file->private_data;
 367         struct ppp *ppp;
 368
 369         if (pf) {
 370                 file->private_data = NULL;
 371                 if (pf->kind == INTERFACE) {
 372                         ppp = PF_TO_PPP(pf);
 373                         if (file == ppp->owner)
 374                                 ppp_shutdown_interface(ppp);
 375                 }
 376                 if (atomic_dec_and_test(&pf->refcnt)) {
 377                         switch (pf->kind) {
 378                         case INTERFACE:
 379                                 ppp_destroy_interface(PF_TO_PPP(pf));
 380                                 break;
 381                         case CHANNEL:
 382                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
 383                                 break;
 384                         }
 385                 }
 386         }
 387         return 0;
 388 }
 389
 390 static ssize_t ppp_read(struct file *file, char __user *buf,
 391                         size_t count, loff_t *ppos)
 392 {
 393         struct ppp_file *pf = file->private_data;
 394         DECLARE_WAITQUEUE(wait, current);
 395         ssize_t ret;
 396         struct sk_buff *skb = NULL;
 397
 398         ret = count;
 399
 400         if (!pf)
 401                 return -ENXIO;
 402         add_wait_queue(&pf->rwait, &wait);
 403         for (;;) {
 404                 set_current_state(TASK_INTERRUPTIBLE);
 405                 skb = skb_dequeue(&pf->rq);
 406                 if (skb)
 407                         break;
 408                 ret = 0;
 409                 if (pf->dead)
 410                         break;
 411                 if (pf->kind == INTERFACE) {
 412                         /*
 413                          * Return 0 (EOF) on an interface that has no
 414                          * channels connected, unless it is looping
 415                          * network traffic (demand mode).
 416                          */
 417                         struct ppp *ppp = PF_TO_PPP(pf);
 418                         if (ppp->n_channels == 0
 419                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 420                                 break;
 421                 }
 422                 ret = -EAGAIN;
 423                 if (file->f_flags & O_NONBLOCK)
 424                         break;
 425                 ret = -ERESTARTSYS;
 426                 if (signal_pending(current))
 427                         break;
 428                 schedule();
 429         }
 430         set_current_state(TASK_RUNNING);
 431         remove_wait_queue(&pf->rwait, &wait);
 432
 433         if (!skb)
 434                 goto out;
 435
 436         ret = -EOVERFLOW;
 437         if (skb->len > count)
 438                 goto outf;
 439         ret = -EFAULT;
 440         if (copy_to_user(buf, skb->data, skb->len))
 441                 goto outf;
 442         ret = skb->len;
 443
 444  outf:
 445         kfree_skb(skb);
 446  out:
 447         return ret;
 448 }
 449
 450 static ssize_t ppp_write(struct file *file, const char __user *buf,
 451                          size_t count, loff_t *ppos)
 452 {
 453         struct ppp_file *pf = file->private_data;
 454         struct sk_buff *skb;
 455         ssize_t ret;
 456
 457         if (!pf)
 458                 return -ENXIO;
 459         ret = -ENOMEM;
 460         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
 461         if (!skb)
 462                 goto out;
 463         skb_reserve(skb, pf->hdrlen);
 464         ret = -EFAULT;
 465         if (copy_from_user(skb_put(skb, count), buf, count)) {
 466                 kfree_skb(skb);
 467                 goto out;
 468         }
 469
 470         skb_queue_tail(&pf->xq, skb);
 471
 472         switch (pf->kind) {
 473         case INTERFACE:
 474                 ppp_xmit_process(PF_TO_PPP(pf));
 475                 break;
 476         case CHANNEL:
 477                 ppp_channel_push(PF_TO_CHANNEL(pf));
 478                 break;
 479         }
 480
 481         ret = count;
 482
 483  out:
 484         return ret;
 485 }
 486
 487 /* No kernel lock - fine */
 488 static unsigned int ppp_poll(struct file *file, poll_table *wait)
 489 {
 490         struct ppp_file *pf = file->private_data;
 491         unsigned int mask;
 492
 493         if (!pf)
 494                 return 0;
 495         poll_wait(file, &pf->rwait, wait);
 496         mask = POLLOUT | POLLWRNORM;
 497         if (skb_peek(&pf->rq))
 498                 mask |= POLLIN | POLLRDNORM;
 499         if (pf->dead)
 500                 mask |= POLLHUP;
 501         else if (pf->kind == INTERFACE) {
 502                 /* see comment in ppp_read */
 503                 struct ppp *ppp = PF_TO_PPP(pf);
 504                 if (ppp->n_channels == 0
 505                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 506                         mask |= POLLIN | POLLRDNORM;
 507         }
 508
 509         return mask;
 510 }
 511
 512 #ifdef CONFIG_PPP_FILTER
 513 static int get_filter(void __user *arg, struct sock_filter **p)
 514 {
 515         struct sock_fprog uprog;
 516         struct sock_filter *code = NULL;
 517         int len, err;
 518
 519         if (copy_from_user(&uprog, arg, sizeof(uprog)))
 520                 return -EFAULT;
 521
 522         if (!uprog.len) {
 523                 *p = NULL;
 524                 return 0;
 525         }
 526
 527         len = uprog.len * sizeof(struct sock_filter);
 528         code = kmalloc(len, GFP_KERNEL);
 529         if (code == NULL)
 530                 return -ENOMEM;
 531
 532         if (copy_from_user(code, uprog.filter, len)) {
 533                 kfree(code);
 534                 return -EFAULT;
 535         }
 536
 537         err = sk_chk_filter(code, uprog.len);
 538         if (err) {
 539                 kfree(code);
 540                 return err;
 541         }
 542
 543         *p = code;
 544         return uprog.len;
 545 }
 546 #endif /* CONFIG_PPP_FILTER */
 547
 548 static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 549 {
 550         struct ppp_file *pf = file->private_data;
 551         struct ppp *ppp;
 552         int err = -EFAULT, val, val2, i;
 553         struct ppp_idle idle;
 554         struct npioctl npi;
 555         int unit, cflags;
 556         struct slcompress *vj;
 557         void __user *argp = (void __user *)arg;
 558         int __user *p = argp;
 559
 560         if (!pf)
 561                 return ppp_unattached_ioctl(pf, file, cmd, arg);
 562
 563         if (cmd == PPPIOCDETACH) {
 564                 /*
 565                  * We have to be careful here... if the file descriptor
 566                  * has been dup'd, we could have another process in the
 567                  * middle of a poll using the same file *, so we had
 568                  * better not free the interface data structures -
 569                  * instead we fail the ioctl.  Even in this case, we
 570                  * shut down the interface if we are the owner of it.
 571                  * Actually, we should get rid of PPPIOCDETACH, userland
 572                  * (i.e. pppd) could achieve the same effect by closing
 573                  * this fd and reopening /dev/ppp.
 574                  */
 575                 err = -EINVAL;
 576                 lock_kernel();
 577                 if (pf->kind == INTERFACE) {
 578                         ppp = PF_TO_PPP(pf);
 579                         if (file == ppp->owner)
 580                                 ppp_shutdown_interface(ppp);
 581                 }
 582                 if (atomic_read(&file->f_count) <= 2) {
 583                         ppp_release(NULL, file);
 584                         err = 0;
 585                 } else
 586                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%d\n",
 587                                atomic_read(&file->f_count));
 588                 unlock_kernel();
 589                 return err;
 590         }
 591
 592         if (pf->kind == CHANNEL) {
 593                 struct channel *pch;
 594                 struct ppp_channel *chan;
 595
 596                 lock_kernel();
 597                 pch = PF_TO_CHANNEL(pf);
 598
 599                 switch (cmd) {
 600                 case PPPIOCCONNECT:
 601                         if (get_user(unit, p))
 602                                 break;
 603                         err = ppp_connect_channel(pch, unit);
 604                         break;
 605
 606                 case PPPIOCDISCONN:
 607                         err = ppp_disconnect_channel(pch);
 608                         break;
 609
 610                 default:
 611                         down_read(&pch->chan_sem);
 612                         chan = pch->chan;
 613                         err = -ENOTTY;
 614                         if (chan && chan->ops->ioctl)
 615                                 err = chan->ops->ioctl(chan, cmd, arg);
 616                         up_read(&pch->chan_sem);
 617                 }
 618                 unlock_kernel();
 619                 return err;
 620         }
 621
 622         if (pf->kind != INTERFACE) {
 623                 /* can't happen */
 624                 printk(KERN_ERR "PPP: not interface or channel??\n");
 625                 return -EINVAL;
 626         }
 627
 628         lock_kernel();
 629         ppp = PF_TO_PPP(pf);
 630         switch (cmd) {
 631         case PPPIOCSMRU:
 632                 if (get_user(val, p))
 633                         break;
 634                 ppp->mru = val;
 635                 err = 0;
 636                 break;
 637
 638         case PPPIOCSFLAGS:
 639                 if (get_user(val, p))
 640                         break;
 641                 ppp_lock(ppp);
 642                 cflags = ppp->flags & ~val;
 643                 ppp->flags = val & SC_FLAG_BITS;
 644                 ppp_unlock(ppp);
 645                 if (cflags & SC_CCP_OPEN)
 646                         ppp_ccp_closed(ppp);
 647                 err = 0;
 648                 break;
 649
 650         case PPPIOCGFLAGS:
 651                 val = ppp->flags | ppp->xstate | ppp->rstate;
 652                 if (put_user(val, p))
 653                         break;
 654                 err = 0;
 655                 break;
 656
 657         case PPPIOCSCOMPRESS:
 658                 err = ppp_set_compress(ppp, arg);
 659                 break;
 660
 661         case PPPIOCGUNIT:
 662                 if (put_user(ppp->file.index, p))
 663                         break;
 664                 err = 0;
 665                 break;
 666
 667         case PPPIOCSDEBUG:
 668                 if (get_user(val, p))
 669                         break;
 670                 ppp->debug = val;
 671                 err = 0;
 672                 break;
 673
 674         case PPPIOCGDEBUG:
 675                 if (put_user(ppp->debug, p))
 676                         break;
 677                 err = 0;
 678                 break;
 679
 680         case PPPIOCGIDLE:
 681                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 682                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
 683                 if (copy_to_user(argp, &idle, sizeof(idle)))
 684                         break;
 685                 err = 0;
 686                 break;
 687
 688         case PPPIOCSMAXCID:
 689                 if (get_user(val, p))
 690                         break;
 691                 val2 = 15;
 692                 if ((val >> 16) != 0) {
 693                         val2 = val >> 16;
 694                         val &= 0xffff;
 695                 }
 696                 vj = slhc_init(val2+1, val+1);
 697                 if (!vj) {
 698                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
 699                         err = -ENOMEM;
 700                         break;
 701                 }
 702                 ppp_lock(ppp);
 703                 if (ppp->vj)
 704                         slhc_free(ppp->vj);
 705                 ppp->vj = vj;
 706                 ppp_unlock(ppp);
 707                 err = 0;
 708                 break;
 709
 710         case PPPIOCGNPMODE:
 711         case PPPIOCSNPMODE:
 712                 if (copy_from_user(&npi, argp, sizeof(npi)))
 713                         break;
 714                 err = proto_to_npindex(npi.protocol);
 715                 if (err < 0)
 716                         break;
 717                 i = err;
 718                 if (cmd == PPPIOCGNPMODE) {
 719                         err = -EFAULT;
 720                         npi.mode = ppp->npmode[i];
 721                         if (copy_to_user(argp, &npi, sizeof(npi)))
 722                                 break;
 723                 } else {
 724                         ppp->npmode[i] = npi.mode;
 725                         /* we may be able to transmit more packets now (??) */
 726                         netif_wake_queue(ppp->dev);
 727                 }
 728                 err = 0;
 729                 break;
 730
 731 #ifdef CONFIG_PPP_FILTER
 732         case PPPIOCSPASS:
 733         {
 734                 struct sock_filter *code;
 735                 err = get_filter(argp, &code);
 736                 if (err >= 0) {
 737                         ppp_lock(ppp);
 738                         kfree(ppp->pass_filter);
 739                         ppp->pass_filter = code;
 740                         ppp->pass_len = err;
 741                         ppp_unlock(ppp);
 742                         err = 0;
 743                 }
 744                 break;
 745         }
 746         case PPPIOCSACTIVE:
 747         {
 748                 struct sock_filter *code;
 749                 err = get_filter(argp, &code);
 750                 if (err >= 0) {
 751                         ppp_lock(ppp);
 752                         kfree(ppp->active_filter);
 753                         ppp->active_filter = code;
 754                         ppp->active_len = err;
 755                         ppp_unlock(ppp);
 756                         err = 0;
 757                 }
 758                 break;
 759         }
 760 #endif /* CONFIG_PPP_FILTER */
 761
 762 #ifdef CONFIG_PPP_MULTILINK
 763         case PPPIOCSMRRU:
 764                 if (get_user(val, p))
 765                         break;
 766                 ppp_recv_lock(ppp);
 767                 ppp->mrru = val;
 768                 ppp_recv_unlock(ppp);
 769                 err = 0;
 770                 break;
 771 #endif /* CONFIG_PPP_MULTILINK */
 772
 773         default:
 774                 err = -ENOTTY;
 775         }
 776         unlock_kernel();
 777         return err;
 778 }
 779
 780 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 781                                 unsigned int cmd, unsigned long arg)
 782 {
 783         int unit, err = -EFAULT;
 784         struct ppp *ppp;
 785         struct channel *chan;
 786         int __user *p = (int __user *)arg;
 787
 788         lock_kernel();
 789         switch (cmd) {
 790         case PPPIOCNEWUNIT:
 791                 /* Create a new ppp unit */
 792                 if (get_user(unit, p))
 793                         break;
 794                 ppp = ppp_create_interface(unit, &err);
 795                 if (!ppp)
 796                         break;
 797                 file->private_data = &ppp->file;
 798                 ppp->owner = file;
 799                 err = -EFAULT;
 800                 if (put_user(ppp->file.index, p))
 801                         break;
 802                 err = 0;
 803                 break;
 804
 805         case PPPIOCATTACH:
 806                 /* Attach to an existing ppp unit */
 807                 if (get_user(unit, p))
 808                         break;
 809                 mutex_lock(&all_ppp_mutex);
 810                 err = -ENXIO;
 811                 ppp = ppp_find_unit(unit);
 812                 if (ppp) {
 813                         atomic_inc(&ppp->file.refcnt);
 814                         file->private_data = &ppp->file;
 815                         err = 0;
 816                 }
 817                 mutex_unlock(&all_ppp_mutex);
 818                 break;
 819
 820         case PPPIOCATTCHAN:
 821                 if (get_user(unit, p))
 822                         break;
 823                 spin_lock_bh(&all_channels_lock);
 824                 err = -ENXIO;
 825                 chan = ppp_find_channel(unit);
 826                 if (chan) {
 827                         atomic_inc(&chan->file.refcnt);
 828                         file->private_data = &chan->file;
 829                         err = 0;
 830                 }
 831                 spin_unlock_bh(&all_channels_lock);
 832                 break;
 833
 834         default:
 835                 err = -ENOTTY;
 836         }
 837         unlock_kernel();
 838         return err;
 839 }
 840
 841 static const struct file_operations ppp_device_fops = {
 842         .owner          = THIS_MODULE,
 843         .read           = ppp_read,
 844         .write          = ppp_write,
 845         .poll           = ppp_poll,
 846         .unlocked_ioctl = ppp_ioctl,
 847         .open           = ppp_open,
 848         .release        = ppp_release
 849 };
 850
 851 #define PPP_MAJOR       108
 852
 853 /* Called at boot time if ppp is compiled into the kernel,
 854    or at module load time (from init_module) if compiled as a module. */
 855 static int __init ppp_init(void)
 856 {
 857         int err;
 858
 859         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
 860         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
 861         if (!err) {
 862                 ppp_class = class_create(THIS_MODULE, "ppp");
 863                 if (IS_ERR(ppp_class)) {
 864                         err = PTR_ERR(ppp_class);
 865                         goto out_chrdev;
 866                 }
 867                 device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), "ppp");
 868         }
 869
 870 out:
 871         if (err)
 872                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
 873         return err;
 874
 875 out_chrdev:
 876         unregister_chrdev(PPP_MAJOR, "ppp");
 877         goto out;
 878 }
 879
 880 /*
 881  * Network interface unit routines.
 882  */
 883 static int
 884 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 885 {
 886         struct ppp *ppp = (struct ppp *) dev->priv;
 887         int npi, proto;
 888         unsigned char *pp;
 889
 890         npi = ethertype_to_npindex(ntohs(skb->protocol));
 891         if (npi < 0)
 892                 goto outf;
 893
 894         /* Drop, accept or reject the packet */
 895         switch (ppp->npmode[npi]) {
 896         case NPMODE_PASS:
 897                 break;
 898         case NPMODE_QUEUE:
 899                 /* it would be nice to have a way to tell the network
 900                    system to queue this one up for later. */
 901                 goto outf;
 902         case NPMODE_DROP:
 903         case NPMODE_ERROR:
 904                 goto outf;
 905         }
 906
 907         /* Put the 2-byte PPP protocol number on the front,
 908            making sure there is room for the address and control fields. */
 909         if (skb_cow_head(skb, PPP_HDRLEN))
 910                 goto outf;
 911
 912         pp = skb_push(skb, 2);
 913         proto = npindex_to_proto[npi];
 914         pp[0] = proto >> 8;
 915         pp[1] = proto;
 916
 917         netif_stop_queue(dev);
 918         skb_queue_tail(&ppp->file.xq, skb);
 919         ppp_xmit_process(ppp);
 920         return 0;
 921
 922  outf:
 923         kfree_skb(skb);
 924         ++ppp->dev->stats.tx_dropped;
 925         return 0;
 926 }
 927
 928 static int
 929 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 930 {
 931         struct ppp *ppp = dev->priv;
 932         int err = -EFAULT;
 933         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
 934         struct ppp_stats stats;
 935         struct ppp_comp_stats cstats;
 936         char *vers;
 937
 938         switch (cmd) {
 939         case SIOCGPPPSTATS:
 940                 ppp_get_stats(ppp, &stats);
 941                 if (copy_to_user(addr, &stats, sizeof(stats)))
 942                         break;
 943                 err = 0;
 944                 break;
 945
 946         case SIOCGPPPCSTATS:
 947                 memset(&cstats, 0, sizeof(cstats));
 948                 if (ppp->xc_state)
 949                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
 950                 if (ppp->rc_state)
 951                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
 952                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
 953                         break;
 954                 err = 0;
 955                 break;
 956
 957         case SIOCGPPPVER:
 958                 vers = PPP_VERSION;
 959                 if (copy_to_user(addr, vers, strlen(vers) + 1))
 960                         break;
 961                 err = 0;
 962                 break;
 963
 964         default:
 965                 err = -EINVAL;
 966         }
 967
 968         return err;
 969 }
 970
 971 static void ppp_setup(struct net_device *dev)
 972 {
 973         dev->hard_header_len = PPP_HDRLEN;
 974         dev->mtu = PPP_MTU;
 975         dev->addr_len = 0;
 976         dev->tx_queue_len = 3;
 977         dev->type = ARPHRD_PPP;
 978         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
 979 }
 980
 981 /*
 982  * Transmit-side routines.
 983  */
 984
 985 /*
 986  * Called to do any work queued up on the transmit side
 987  * that can now be done.
 988  */
 989 static void
 990 ppp_xmit_process(struct ppp *ppp)
 991 {
 992         struct sk_buff *skb;
 993
 994         ppp_xmit_lock(ppp);
 995         if (ppp->dev) {
 996                 ppp_push(ppp);
 997                 while (!ppp->xmit_pending
 998                        && (skb = skb_dequeue(&ppp->file.xq)))
 999                         ppp_send_frame(ppp, skb);
1000                 /* If there's no work left to do, tell the core net
1001                    code that we can accept some more. */
1002                 if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
1003                         netif_wake_queue(ppp->dev);
1004         }
1005         ppp_xmit_unlock(ppp);
1006 }
1007
1008 static inline struct sk_buff *
1009 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1010 {
1011         struct sk_buff *new_skb;
1012         int len;
1013         int new_skb_size = ppp->dev->mtu +
1014                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1015         int compressor_skb_size = ppp->dev->mtu +
1016                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1017         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1018         if (!new_skb) {
1019                 if (net_ratelimit())
1020                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1021                 return NULL;
1022         }
1023         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1024                 skb_reserve(new_skb,
1025                             ppp->dev->hard_header_len - PPP_HDRLEN);
1026
1027         /* compressor still expects A/C bytes in hdr */
1028         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1029                                    new_skb->data, skb->len + 2,
1030                                    compressor_skb_size);
1031         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1032                 kfree_skb(skb);
1033                 skb = new_skb;
1034                 skb_put(skb, len);
1035                 skb_pull(skb, 2);       /* pull off A/C bytes */
1036         } else if (len == 0) {
1037                 /* didn't compress, or CCP not up yet */
1038                 kfree_skb(new_skb);
1039                 new_skb = skb;
1040         } else {
1041                 /*
1042                  * (len < 0)
1043                  * MPPE requires that we do not send unencrypted
1044                  * frames.  The compressor will return -1 if we
1045                  * should drop the frame.  We cannot simply test
1046                  * the compress_proto because MPPE and MPPC share
1047                  * the same number.
1048                  */
1049                 if (net_ratelimit())
1050                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1051                 kfree_skb(skb);
1052                 kfree_skb(new_skb);
1053                 new_skb = NULL;
1054         }
1055         return new_skb;
1056 }
1057
1058 /*
1059  * Compress and send a frame.
1060  * The caller should have locked the xmit path,
1061  * and xmit_pending should be 0.
1062  */
1063 static void
1064 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1065 {
1066         int proto = PPP_PROTO(skb);
1067         struct sk_buff *new_skb;
1068         int len;
1069         unsigned char *cp;
1070
1071         if (proto < 0x8000) {
1072 #ifdef CONFIG_PPP_FILTER
1073                 /* check if we should pass this packet */
1074                 /* the filter instructions are constructed assuming
1075                    a four-byte PPP header on each packet */
1076                 *skb_push(skb, 2) = 1;
1077                 if (ppp->pass_filter
1078                     && sk_run_filter(skb, ppp->pass_filter,
1079                                      ppp->pass_len) == 0) {
1080                         if (ppp->debug & 1)
1081                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1082                         kfree_skb(skb);
1083                         return;
1084                 }
1085                 /* if this packet passes the active filter, record the time */
1086                 if (!(ppp->active_filter
1087                       && sk_run_filter(skb, ppp->active_filter,
1088                                        ppp->active_len) == 0))
1089                         ppp->last_xmit = jiffies;
1090                 skb_pull(skb, 2);
1091 #else
1092                 /* for data packets, record the time */
1093                 ppp->last_xmit = jiffies;
1094 #endif /* CONFIG_PPP_FILTER */
1095         }
1096
1097         ++ppp->dev->stats.tx_packets;
1098         ppp->dev->stats.tx_bytes += skb->len - 2;
1099
1100         switch (proto) {
1101         case PPP_IP:
1102                 if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1103                         break;
1104                 /* try to do VJ TCP header compression */
1105                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1106                                     GFP_ATOMIC);
1107                 if (!new_skb) {
1108                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1109                         goto drop;
1110                 }
1111                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1112                 cp = skb->data + 2;
1113                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1114                                     new_skb->data + 2, &cp,
1115                                     !(ppp->flags & SC_NO_TCP_CCID));
1116                 if (cp == skb->data + 2) {
1117                         /* didn't compress */
1118                         kfree_skb(new_skb);
1119                 } else {
1120                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1121                                 proto = PPP_VJC_COMP;
1122                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1123                         } else {
1124                                 proto = PPP_VJC_UNCOMP;
1125                                 cp[0] = skb->data[2];
1126                         }
1127                         kfree_skb(skb);
1128                         skb = new_skb;
1129                         cp = skb_put(skb, len + 2);
1130                         cp[0] = 0;
1131                         cp[1] = proto;
1132                 }
1133                 break;
1134
1135         case PPP_CCP:
1136                 /* peek at outbound CCP frames */
1137                 ppp_ccp_peek(ppp, skb, 0);
1138                 break;
1139         }
1140
1141         /* try to do packet compression */
1142         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state
1143             && proto != PPP_LCP && proto != PPP_CCP) {
1144                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1145                         if (net_ratelimit())
1146                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1147                         goto drop;
1148                 }
1149                 skb = pad_compress_skb(ppp, skb);
1150                 if (!skb)
1151                         goto drop;
1152         }
1153
1154         /*
1155          * If we are waiting for traffic (demand dialling),
1156          * queue it up for pppd to receive.
1157          */
1158         if (ppp->flags & SC_LOOP_TRAFFIC) {
1159                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1160                         goto drop;
1161                 skb_queue_tail(&ppp->file.rq, skb);
1162                 wake_up_interruptible(&ppp->file.rwait);
1163                 return;
1164         }
1165
1166         ppp->xmit_pending = skb;
1167         ppp_push(ppp);
1168         return;
1169
1170  drop:
1171         if (skb)
1172                 kfree_skb(skb);
1173         ++ppp->dev->stats.tx_errors;
1174 }
1175
1176 /*
1177  * Try to send the frame in xmit_pending.
1178  * The caller should have the xmit path locked.
1179  */
1180 static void
1181 ppp_push(struct ppp *ppp)
1182 {
1183         struct list_head *list;
1184         struct channel *pch;
1185         struct sk_buff *skb = ppp->xmit_pending;
1186
1187         if (!skb)
1188                 return;
1189
1190         list = &ppp->channels;
1191         if (list_empty(list)) {
1192                 /* nowhere to send the packet, just drop it */
1193                 ppp->xmit_pending = NULL;
1194                 kfree_skb(skb);
1195                 return;
1196         }
1197
1198         if ((ppp->flags & SC_MULTILINK) == 0) {
1199                 /* not doing multilink: send it down the first channel */
1200                 list = list->next;
1201                 pch = list_entry(list, struct channel, clist);
1202
1203                 spin_lock_bh(&pch->downl);
1204                 if (pch->chan) {
1205                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1206                                 ppp->xmit_pending = NULL;
1207                 } else {
1208                         /* channel got unregistered */
1209                         kfree_skb(skb);
1210                         ppp->xmit_pending = NULL;
1211                 }
1212                 spin_unlock_bh(&pch->downl);
1213                 return;
1214         }
1215
1216 #ifdef CONFIG_PPP_MULTILINK
1217         /* Multilink: fragment the packet over as many links
1218            as can take the packet at the moment. */
1219         if (!ppp_mp_explode(ppp, skb))
1220                 return;
1221 #endif /* CONFIG_PPP_MULTILINK */
1222
1223         ppp->xmit_pending = NULL;
1224         kfree_skb(skb);
1225 }
1226
1227 #ifdef CONFIG_PPP_MULTILINK
1228 /*
1229  * Divide a packet to be transmitted into fragments and
1230  * send them out the individual links.
1231  */
1232 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1233 {
1234         int len, fragsize;
1235         int i, bits, hdrlen, mtu;
1236         int flen;
1237         int navail, nfree;
1238         int nbigger;
1239         unsigned char *p, *q;
1240         struct list_head *list;
1241         struct channel *pch;
1242         struct sk_buff *frag;
1243         struct ppp_channel *chan;
1244
1245         nfree = 0;      /* # channels which have no packet already queued */
1246         navail = 0;     /* total # of usable channels (not deregistered) */
1247         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1248         i = 0;
1249         list_for_each_entry(pch, &ppp->channels, clist) {
1250                 navail += pch->avail = (pch->chan != NULL);
1251                 if (pch->avail) {
1252                         if (skb_queue_empty(&pch->file.xq) ||
1253                             !pch->had_frag) {
1254                                 pch->avail = 2;
1255                                 ++nfree;
1256                         }
1257                         if (!pch->had_frag && i < ppp->nxchan)
1258                                 ppp->nxchan = i;
1259                 }
1260                 ++i;
1261         }
1262
1263         /*
1264          * Don't start sending this packet unless at least half of
1265          * the channels are free.  This gives much better TCP
1266          * performance if we have a lot of channels.
1267          */
1268         if (nfree == 0 || nfree < navail / 2)
1269                 return 0;       /* can't take now, leave it in xmit_pending */
1270
1271         /* Do protocol field compression (XXX this should be optional) */
1272         p = skb->data;
1273         len = skb->len;
1274         if (*p == 0) {
1275                 ++p;
1276                 --len;
1277         }
1278
1279         /*
1280          * Decide on fragment size.
1281          * We create a fragment for each free channel regardless of
1282          * how small they are (i.e. even 0 length) in order to minimize
1283          * the time that it will take to detect when a channel drops
1284          * a fragment.
1285          */
1286         fragsize = len;
1287         if (nfree > 1)
1288                 fragsize = DIV_ROUND_UP(fragsize, nfree);
1289         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1290            except if nbigger==0, then they all get fragsize. */
1291         nbigger = len % nfree;
1292
1293         /* skip to the channel after the one we last used
1294            and start at that one */
1295         list = &ppp->channels;
1296         for (i = 0; i < ppp->nxchan; ++i) {
1297                 list = list->next;
1298                 if (list == &ppp->channels) {
1299                         i = 0;
1300                         break;
1301                 }
1302         }
1303
1304         /* create a fragment for each channel */
1305         bits = B;
1306         while (nfree > 0 || len > 0) {
1307                 list = list->next;
1308                 if (list == &ppp->channels) {
1309                         i = 0;
1310                         continue;
1311                 }
1312                 pch = list_entry(list, struct channel, clist);
1313                 ++i;
1314                 if (!pch->avail)
1315                         continue;
1316
1317                 /*
1318                  * Skip this channel if it has a fragment pending already and
1319                  * we haven't given a fragment to all of the free channels.
1320                  */
1321                 if (pch->avail == 1) {
1322                         if (nfree > 0)
1323                                 continue;
1324                 } else {
1325                         --nfree;
1326                         pch->avail = 1;
1327                 }
1328
1329                 /* check the channel's mtu and whether it is still attached. */
1330                 spin_lock_bh(&pch->downl);
1331                 if (pch->chan == NULL) {
1332                         /* can't use this channel, it's being deregistered */
1333                         spin_unlock_bh(&pch->downl);
1334                         pch->avail = 0;
1335                         if (--navail == 0)
1336                                 break;
1337                         continue;
1338                 }
1339
1340                 /*
1341                  * Create a fragment for this channel of
1342                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1343                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1344                  * MTU, so we use mtu = 2 + hdrlen.
1345                  */
1346                 if (fragsize > len)
1347                         fragsize = len;
1348                 flen = fragsize;
1349                 mtu = pch->chan->mtu + 2 - hdrlen;
1350                 if (mtu < 4)
1351                         mtu = 4;
1352                 if (flen > mtu)
1353                         flen = mtu;
1354                 if (flen == len && nfree == 0)
1355                         bits |= E;
1356                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1357                 if (!frag)
1358                         goto noskb;
1359                 q = skb_put(frag, flen + hdrlen);
1360
1361                 /* make the MP header */
1362                 q[0] = PPP_MP >> 8;
1363                 q[1] = PPP_MP;
1364                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1365                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1366                         q[3] = ppp->nxseq;
1367                 } else {
1368                         q[2] = bits;
1369                         q[3] = ppp->nxseq >> 16;
1370                         q[4] = ppp->nxseq >> 8;
1371                         q[5] = ppp->nxseq;
1372                 }
1373
1374                 /*
1375                  * Copy the data in.
1376                  * Unfortunately there is a bug in older versions of
1377                  * the Linux PPP multilink reconstruction code where it
1378                  * drops 0-length fragments.  Therefore we make sure the
1379                  * fragment has at least one byte of data.  Any bytes
1380                  * we add in this situation will end up as padding on the
1381                  * end of the reconstructed packet.
1382                  */
1383                 if (flen == 0)
1384                         *skb_put(frag, 1) = 0;
1385                 else
1386                         memcpy(q + hdrlen, p, flen);
1387
1388                 /* try to send it down the channel */
1389                 chan = pch->chan;
1390                 if (!skb_queue_empty(&pch->file.xq) ||
1391                     !chan->ops->start_xmit(chan, frag))
1392                         skb_queue_tail(&pch->file.xq, frag);
1393                 pch->had_frag = 1;
1394                 p += flen;
1395                 len -= flen;
1396                 ++ppp->nxseq;
1397                 bits = 0;
1398                 spin_unlock_bh(&pch->downl);
1399
1400                 if (--nbigger == 0 && fragsize > 0)
1401                         --fragsize;
1402         }
1403         ppp->nxchan = i;
1404
1405         return 1;
1406
1407  noskb:
1408         spin_unlock_bh(&pch->downl);
1409         if (ppp->debug & 1)
1410                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1411         ++ppp->dev->stats.tx_errors;
1412         ++ppp->nxseq;
1413         return 1;       /* abandon the frame */
1414 }
1415 #endif /* CONFIG_PPP_MULTILINK */
1416
1417 /*
1418  * Try to send data out on a channel.
1419  */
1420 static void
1421 ppp_channel_push(struct channel *pch)
1422 {
1423         struct sk_buff *skb;
1424         struct ppp *ppp;
1425
1426         spin_lock_bh(&pch->downl);
1427         if (pch->chan) {
1428                 while (!skb_queue_empty(&pch->file.xq)) {
1429                         skb = skb_dequeue(&pch->file.xq);
1430                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1431                                 /* put the packet back and try again later */
1432                                 skb_queue_head(&pch->file.xq, skb);
1433                                 break;
1434                         }
1435                 }
1436         } else {
1437                 /* channel got deregistered */
1438                 skb_queue_purge(&pch->file.xq);
1439         }
1440         spin_unlock_bh(&pch->downl);
1441         /* see if there is anything from the attached unit to be sent */
1442         if (skb_queue_empty(&pch->file.xq)) {
1443                 read_lock_bh(&pch->upl);
1444                 ppp = pch->ppp;
1445                 if (ppp)
1446                         ppp_xmit_process(ppp);
1447                 read_unlock_bh(&pch->upl);
1448         }
1449 }
1450
1451 /*
1452  * Receive-side routines.
1453  */
1454
1455 /* misuse a few fields of the skb for MP reconstruction */
1456 #define sequence        priority
1457 #define BEbits          cb[0]
1458
1459 static inline void
1460 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1461 {
1462         ppp_recv_lock(ppp);
1463         /* ppp->dev == 0 means interface is closing down */
1464         if (ppp->dev)
1465                 ppp_receive_frame(ppp, skb, pch);
1466         else
1467                 kfree_skb(skb);
1468         ppp_recv_unlock(ppp);
1469 }
1470
1471 void
1472 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1473 {
1474         struct channel *pch = chan->ppp;
1475         int proto;
1476
1477         if (!pch || skb->len == 0) {
1478                 kfree_skb(skb);
1479                 return;
1480         }
1481
1482         proto = PPP_PROTO(skb);
1483         read_lock_bh(&pch->upl);
1484         if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1485                 /* put it on the channel queue */
1486                 skb_queue_tail(&pch->file.rq, skb);
1487                 /* drop old frames if queue too long */
1488                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1489                        && (skb = skb_dequeue(&pch->file.rq)))
1490                         kfree_skb(skb);
1491                 wake_up_interruptible(&pch->file.rwait);
1492         } else {
1493                 ppp_do_recv(pch->ppp, skb, pch);
1494         }
1495         read_unlock_bh(&pch->upl);
1496 }
1497
1498 /* Put a 0-length skb in the receive queue as an error indication */
1499 void
1500 ppp_input_error(struct ppp_channel *chan, int code)
1501 {
1502         struct channel *pch = chan->ppp;
1503         struct sk_buff *skb;
1504
1505         if (!pch)
1506                 return;
1507
1508         read_lock_bh(&pch->upl);
1509         if (pch->ppp) {
1510                 skb = alloc_skb(0, GFP_ATOMIC);
1511                 if (skb) {
1512                         skb->len = 0;           /* probably unnecessary */
1513                         skb->cb[0] = code;
1514                         ppp_do_recv(pch->ppp, skb, pch);
1515                 }
1516         }
1517         read_unlock_bh(&pch->upl);
1518 }
1519
1520 /*
1521  * We come in here to process a received frame.
1522  * The receive side of the ppp unit is locked.
1523  */
1524 static void
1525 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1526 {
1527         if (pskb_may_pull(skb, 2)) {
1528 #ifdef CONFIG_PPP_MULTILINK
1529                 /* XXX do channel-level decompression here */
1530                 if (PPP_PROTO(skb) == PPP_MP)
1531                         ppp_receive_mp_frame(ppp, skb, pch);
1532                 else
1533 #endif /* CONFIG_PPP_MULTILINK */
1534                         ppp_receive_nonmp_frame(ppp, skb);
1535                 return;
1536         }
1537
1538         if (skb->len > 0)
1539                 /* note: a 0-length skb is used as an error indication */
1540                 ++ppp->dev->stats.rx_length_errors;
1541
1542         kfree_skb(skb);
1543         ppp_receive_error(ppp);
1544 }
1545
1546 static void
1547 ppp_receive_error(struct ppp *ppp)
1548 {
1549         ++ppp->dev->stats.rx_errors;
1550         if (ppp->vj)
1551                 slhc_toss(ppp->vj);
1552 }
1553
1554 static void
1555 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1556 {
1557         struct sk_buff *ns;
1558         int proto, len, npi;
1559
1560         /*
1561          * Decompress the frame, if compressed.
1562          * Note that some decompressors need to see uncompressed frames
1563          * that come in as well as compressed frames.
1564          */
1565         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)
1566             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1567                 skb = ppp_decompress_frame(ppp, skb);
1568
1569         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1570                 goto err;
1571
1572         proto = PPP_PROTO(skb);
1573         switch (proto) {
1574         case PPP_VJC_COMP:
1575                 /* decompress VJ compressed packets */
1576                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1577                         goto err;
1578
1579                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1580                         /* copy to a new sk_buff with more tailroom */
1581                         ns = dev_alloc_skb(skb->len + 128);
1582                         if (!ns) {
1583                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1584                                 goto err;
1585                         }
1586                         skb_reserve(ns, 2);
1587                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1588                         kfree_skb(skb);
1589                         skb = ns;
1590                 }
1591                 else
1592                         skb->ip_summed = CHECKSUM_NONE;
1593
1594                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1595                 if (len <= 0) {
1596                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1597                         goto err;
1598                 }
1599                 len += 2;
1600                 if (len > skb->len)
1601                         skb_put(skb, len - skb->len);
1602                 else if (len < skb->len)
1603                         skb_trim(skb, len);
1604                 proto = PPP_IP;
1605                 break;
1606
1607         case PPP_VJC_UNCOMP:
1608                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1609                         goto err;
1610
1611                 /* Until we fix the decompressor need to make sure
1612                  * data portion is linear.
1613                  */
1614                 if (!pskb_may_pull(skb, skb->len))
1615                         goto err;
1616
1617                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1618                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1619                         goto err;
1620                 }
1621                 proto = PPP_IP;
1622                 break;
1623
1624         case PPP_CCP:
1625                 ppp_ccp_peek(ppp, skb, 1);
1626                 break;
1627         }
1628
1629         ++ppp->dev->stats.rx_packets;
1630         ppp->dev->stats.rx_bytes += skb->len - 2;
1631
1632         npi = proto_to_npindex(proto);
1633         if (npi < 0) {
1634                 /* control or unknown frame - pass it to pppd */
1635                 skb_queue_tail(&ppp->file.rq, skb);
1636                 /* limit queue length by dropping old frames */
1637                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1638                        && (skb = skb_dequeue(&ppp->file.rq)))
1639                         kfree_skb(skb);
1640                 /* wake up any process polling or blocking on read */
1641                 wake_up_interruptible(&ppp->file.rwait);
1642
1643         } else {
1644                 /* network protocol frame - give it to the kernel */
1645
1646 #ifdef CONFIG_PPP_FILTER
1647                 /* check if the packet passes the pass and active filters */
1648                 /* the filter instructions are constructed assuming
1649                    a four-byte PPP header on each packet */
1650                 if (ppp->pass_filter || ppp->active_filter) {
1651                         if (skb_cloned(skb) &&
1652                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
1653                                 goto err;
1654
1655                         *skb_push(skb, 2) = 0;
1656                         if (ppp->pass_filter
1657                             && sk_run_filter(skb, ppp->pass_filter,
1658                                              ppp->pass_len) == 0) {
1659                                 if (ppp->debug & 1)
1660                                         printk(KERN_DEBUG "PPP: inbound frame "
1661                                                "not passed\n");
1662                                 kfree_skb(skb);
1663                                 return;
1664                         }
1665                         if (!(ppp->active_filter
1666                               && sk_run_filter(skb, ppp->active_filter,
1667                                                ppp->active_len) == 0))
1668                                 ppp->last_recv = jiffies;
1669                         __skb_pull(skb, 2);
1670                 } else
1671 #endif /* CONFIG_PPP_FILTER */
1672                         ppp->last_recv = jiffies;
1673
1674                 if ((ppp->dev->flags & IFF_UP) == 0
1675                     || ppp->npmode[npi] != NPMODE_PASS) {
1676                         kfree_skb(skb);
1677                 } else {
1678                         /* chop off protocol */
1679                         skb_pull_rcsum(skb, 2);
1680                         skb->dev = ppp->dev;
1681                         skb->protocol = htons(npindex_to_ethertype[npi]);
1682                         skb_reset_mac_header(skb);
1683                         netif_rx(skb);
1684                         ppp->dev->last_rx = jiffies;
1685                 }
1686         }
1687         return;
1688
1689  err:
1690         kfree_skb(skb);
1691         ppp_receive_error(ppp);
1692 }
1693
1694 static struct sk_buff *
1695 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1696 {
1697         int proto = PPP_PROTO(skb);
1698         struct sk_buff *ns;
1699         int len;
1700
1701         /* Until we fix all the decompressor's need to make sure
1702          * data portion is linear.
1703          */
1704         if (!pskb_may_pull(skb, skb->len))
1705                 goto err;
1706
1707         if (proto == PPP_COMP) {
1708                 int obuff_size;
1709
1710                 switch(ppp->rcomp->compress_proto) {
1711                 case CI_MPPE:
1712                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1713                         break;
1714                 default:
1715                         obuff_size = ppp->mru + PPP_HDRLEN;
1716                         break;
1717                 }
1718
1719                 ns = dev_alloc_skb(obuff_size);
1720                 if (!ns) {
1721                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1722                         goto err;
1723                 }
1724                 /* the decompressor still expects the A/C bytes in the hdr */
1725                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1726                                 skb->len + 2, ns->data, obuff_size);
1727                 if (len < 0) {
1728                         /* Pass the compressed frame to pppd as an
1729                            error indication. */
1730                         if (len == DECOMP_FATALERROR)
1731                                 ppp->rstate |= SC_DC_FERROR;
1732                         kfree_skb(ns);
1733                         goto err;
1734                 }
1735
1736                 kfree_skb(skb);
1737                 skb = ns;
1738                 skb_put(skb, len);
1739                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1740
1741         } else {
1742                 /* Uncompressed frame - pass to decompressor so it
1743                    can update its dictionary if necessary. */
1744                 if (ppp->rcomp->incomp)
1745                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1746                                            skb->len + 2);
1747         }
1748
1749         return skb;
1750
1751  err:
1752         ppp->rstate |= SC_DC_ERROR;
1753         ppp_receive_error(ppp);
1754         return skb;
1755 }
1756
1757 #ifdef CONFIG_PPP_MULTILINK
1758 /*
1759  * Receive a multilink frame.
1760  * We put it on the reconstruction queue and then pull off
1761  * as many completed frames as we can.
1762  */
1763 static void
1764 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1765 {
1766         u32 mask, seq;
1767         struct channel *ch;
1768         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1769
1770         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1771                 goto err;               /* no good, throw it away */
1772
1773         /* Decode sequence number and begin/end bits */
1774         if (ppp->flags & SC_MP_SHORTSEQ) {
1775                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1776                 mask = 0xfff;
1777         } else {
1778                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1779                 mask = 0xffffff;
1780         }
1781         skb->BEbits = skb->data[2];
1782         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1783
1784         /*
1785          * Do protocol ID decompression on the first fragment of each packet.
1786          */
1787         if ((skb->BEbits & B) && (skb->data[0] & 1))
1788                 *skb_push(skb, 1) = 0;
1789
1790         /*
1791          * Expand sequence number to 32 bits, making it as close
1792          * as possible to ppp->minseq.
1793          */
1794         seq |= ppp->minseq & ~mask;
1795         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1796                 seq += mask + 1;
1797         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1798                 seq -= mask + 1;        /* should never happen */
1799         skb->sequence = seq;
1800         pch->lastseq = seq;
1801
1802         /*
1803          * If this packet comes before the next one we were expecting,
1804          * drop it.
1805          */
1806         if (seq_before(seq, ppp->nextseq)) {
1807                 kfree_skb(skb);
1808                 ++ppp->dev->stats.rx_dropped;
1809                 ppp_receive_error(ppp);
1810                 return;
1811         }
1812
1813         /*
1814          * Reevaluate minseq, the minimum over all channels of the
1815          * last sequence number received on each channel.  Because of
1816          * the increasing sequence number rule, we know that any fragment
1817          * before `minseq' which hasn't arrived is never going to arrive.
1818          * The list of channels can't change because we have the receive
1819          * side of the ppp unit locked.
1820          */
1821         list_for_each_entry(ch, &ppp->channels, clist) {
1822                 if (seq_before(ch->lastseq, seq))
1823                         seq = ch->lastseq;
1824         }
1825         if (seq_before(ppp->minseq, seq))
1826                 ppp->minseq = seq;
1827
1828         /* Put the fragment on the reconstruction queue */
1829         ppp_mp_insert(ppp, skb);
1830
1831         /* If the queue is getting long, don't wait any longer for packets
1832            before the start of the queue. */
1833         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN
1834             && seq_before(ppp->minseq, ppp->mrq.next->sequence))
1835                 ppp->minseq = ppp->mrq.next->sequence;
1836
1837         /* Pull completed packets off the queue and receive them. */
1838         while ((skb = ppp_mp_reconstruct(ppp)))
1839                 ppp_receive_nonmp_frame(ppp, skb);
1840
1841         return;
1842
1843  err:
1844         kfree_skb(skb);
1845         ppp_receive_error(ppp);
1846 }
1847
1848 /*
1849  * Insert a fragment on the MP reconstruction queue.
1850  * The queue is ordered by increasing sequence number.
1851  */
1852 static void
1853 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1854 {
1855         struct sk_buff *p;
1856         struct sk_buff_head *list = &ppp->mrq;
1857         u32 seq = skb->sequence;
1858
1859         /* N.B. we don't need to lock the list lock because we have the
1860            ppp unit receive-side lock. */
1861         for (p = list->next; p != (struct sk_buff *)list; p = p->next)
1862                 if (seq_before(seq, p->sequence))
1863                         break;
1864         __skb_insert(skb, p->prev, p, list);
1865 }
1866
1867 /*
1868  * Reconstruct a packet from the MP fragment queue.
1869  * We go through increasing sequence numbers until we find a
1870  * complete packet, or we get to the sequence number for a fragment
1871  * which hasn't arrived but might still do so.
1872  */
1873 static struct sk_buff *
1874 ppp_mp_reconstruct(struct ppp *ppp)
1875 {
1876         u32 seq = ppp->nextseq;
1877         u32 minseq = ppp->minseq;
1878         struct sk_buff_head *list = &ppp->mrq;
1879         struct sk_buff *p, *next;
1880         struct sk_buff *head, *tail;
1881         struct sk_buff *skb = NULL;
1882         int lost = 0, len = 0;
1883
1884         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1885                 return NULL;
1886         head = list->next;
1887         tail = NULL;
1888         for (p = head; p != (struct sk_buff *) list; p = next) {
1889                 next = p->next;
1890                 if (seq_before(p->sequence, seq)) {
1891                         /* this can't happen, anyway ignore the skb */
1892                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1893                                p->sequence, seq);
1894                         head = next;
1895                         continue;
1896                 }
1897                 if (p->sequence != seq) {
1898                         /* Fragment `seq' is missing.  If it is after
1899                            minseq, it might arrive later, so stop here. */
1900                         if (seq_after(seq, minseq))
1901                                 break;
1902                         /* Fragment `seq' is lost, keep going. */
1903                         lost = 1;
1904                         seq = seq_before(minseq, p->sequence)?
1905                                 minseq + 1: p->sequence;
1906                         next = p;
1907                         continue;
1908                 }
1909
1910                 /*
1911                  * At this point we know that all the fragments from
1912                  * ppp->nextseq to seq are either present or lost.
1913                  * Also, there are no complete packets in the queue
1914                  * that have no missing fragments and end before this
1915                  * fragment.
1916                  */
1917
1918                 /* B bit set indicates this fragment starts a packet */
1919                 if (p->BEbits & B) {
1920                         head = p;
1921                         lost = 0;
1922                         len = 0;
1923                 }
1924
1925                 len += p->len;
1926
1927                 /* Got a complete packet yet? */
1928                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1929                         if (len > ppp->mrru + 2) {
1930                                 ++ppp->dev->stats.rx_length_errors;
1931                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1932                                        " is too long (%d)\n", len);
1933                         } else if (p == head) {
1934                                 /* fragment is complete packet - reuse skb */
1935                                 tail = p;
1936                                 skb = skb_get(p);
1937                                 break;
1938                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1939                                 ++ppp->dev->stats.rx_missed_errors;
1940                                 printk(KERN_DEBUG "PPP: no memory for "
1941                                        "reconstructed packet");
1942                         } else {
1943                                 tail = p;
1944                                 break;
1945                         }
1946                         ppp->nextseq = seq + 1;
1947                 }
1948
1949                 /*
1950                  * If this is the ending fragment of a packet,
1951                  * and we haven't found a complete valid packet yet,
1952                  * we can discard up to and including this fragment.
1953                  */
1954                 if (p->BEbits & E)
1955                         head = next;
1956
1957                 ++seq;
1958         }
1959
1960         /* If we have a complete packet, copy it all into one skb. */
1961         if (tail != NULL) {
1962                 /* If we have discarded any fragments,
1963                    signal a receive error. */
1964                 if (head->sequence != ppp->nextseq) {
1965                         if (ppp->debug & 1)
1966                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1967                                        ppp->nextseq, head->sequence-1);
1968                         ++ppp->dev->stats.rx_dropped;
1969                         ppp_receive_error(ppp);
1970                 }
1971
1972                 if (head != tail)
1973                         /* copy to a single skb */
1974                         for (p = head; p != tail->next; p = p->next)
1975                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1976                 ppp->nextseq = tail->sequence + 1;
1977                 head = tail->next;
1978         }
1979
1980         /* Discard all the skbuffs that we have copied the data out of
1981            or that we can't use. */
1982         while ((p = list->next) != head) {
1983                 __skb_unlink(p, list);
1984                 kfree_skb(p);
1985         }
1986
1987         return skb;
1988 }
1989 #endif /* CONFIG_PPP_MULTILINK */
1990
1991 /*
1992  * Channel interface.
1993  */
1994
1995 /*
1996  * Create a new, unattached ppp channel.
1997  */
1998 int
1999 ppp_register_channel(struct ppp_channel *chan)
2000 {
2001         struct channel *pch;
2002
2003         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2004         if (!pch)
2005                 return -ENOMEM;
2006         pch->ppp = NULL;
2007         pch->chan = chan;
2008         chan->ppp = pch;
2009         init_ppp_file(&pch->file, CHANNEL);
2010         pch->file.hdrlen = chan->hdrlen;
2011 #ifdef CONFIG_PPP_MULTILINK
2012         pch->lastseq = -1;
2013 #endif /* CONFIG_PPP_MULTILINK */
2014         init_rwsem(&pch->chan_sem);
2015         spin_lock_init(&pch->downl);
2016         rwlock_init(&pch->upl);
2017         spin_lock_bh(&all_channels_lock);
2018         pch->file.index = ++last_channel_index;
2019         list_add(&pch->list, &new_channels);
2020         atomic_inc(&channel_count);
2021         spin_unlock_bh(&all_channels_lock);
2022         return 0;
2023 }
2024
2025 /*
2026  * Return the index of a channel.
2027  */
2028 int ppp_channel_index(struct ppp_channel *chan)
2029 {
2030         struct channel *pch = chan->ppp;
2031
2032         if (pch)
2033                 return pch->file.index;
2034         return -1;
2035 }
2036
2037 /*
2038  * Return the PPP unit number to which a channel is connected.
2039  */
2040 int ppp_unit_number(struct ppp_channel *chan)
2041 {
2042         struct channel *pch = chan->ppp;
2043         int unit = -1;
2044
2045         if (pch) {
2046                 read_lock_bh(&pch->upl);
2047                 if (pch->ppp)
2048                         unit = pch->ppp->file.index;
2049                 read_unlock_bh(&pch->upl);
2050         }
2051         return unit;
2052 }
2053
2054 /*
2055  * Disconnect a channel from the generic layer.
2056  * This must be called in process context.
2057  */
2058 void
2059 ppp_unregister_channel(struct ppp_channel *chan)
2060 {
2061         struct channel *pch = chan->ppp;
2062
2063         if (!pch)
2064                 return;         /* should never happen */
2065         chan->ppp = NULL;
2066
2067         /*
2068          * This ensures that we have returned from any calls into the
2069          * the channel's start_xmit or ioctl routine before we proceed.
2070          */
2071         down_write(&pch->chan_sem);
2072         spin_lock_bh(&pch->downl);
2073         pch->chan = NULL;
2074         spin_unlock_bh(&pch->downl);
2075         up_write(&pch->chan_sem);
2076         ppp_disconnect_channel(pch);
2077         spin_lock_bh(&all_channels_lock);
2078         list_del(&pch->list);
2079         spin_unlock_bh(&all_channels_lock);
2080         pch->file.dead = 1;
2081         wake_up_interruptible(&pch->file.rwait);
2082         if (atomic_dec_and_test(&pch->file.refcnt))
2083                 ppp_destroy_channel(pch);
2084 }
2085
2086 /*
2087  * Callback from a channel when it can accept more to transmit.
2088  * This should be called at BH/softirq level, not interrupt level.
2089  */
2090 void
2091 ppp_output_wakeup(struct ppp_channel *chan)
2092 {
2093         struct channel *pch = chan->ppp;
2094
2095         if (!pch)
2096                 return;
2097         ppp_channel_push(pch);
2098 }
2099
2100 /*
2101  * Compression control.
2102  */
2103
2104 /* Process the PPPIOCSCOMPRESS ioctl. */
2105 static int
2106 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2107 {
2108         int err;
2109         struct compressor *cp, *ocomp;
2110         struct ppp_option_data data;
2111         void *state, *ostate;
2112         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2113
2114         err = -EFAULT;
2115         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2116             || (data.length <= CCP_MAX_OPTION_LENGTH
2117                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2118                 goto out;
2119         err = -EINVAL;
2120         if (data.length > CCP_MAX_OPTION_LENGTH
2121             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2122                 goto out;
2123
2124         cp = find_compressor(ccp_option[0]);
2125 #ifdef CONFIG_KMOD
2126         if (!cp) {
2127                 request_module("ppp-compress-%d", ccp_option[0]);
2128                 cp = find_compressor(ccp_option[0]);
2129         }
2130 #endif /* CONFIG_KMOD */
2131         if (!cp)
2132                 goto out;
2133
2134         err = -ENOBUFS;
2135         if (data.transmit) {
2136                 state = cp->comp_alloc(ccp_option, data.length);
2137                 if (state) {
2138                         ppp_xmit_lock(ppp);
2139                         ppp->xstate &= ~SC_COMP_RUN;
2140                         ocomp = ppp->xcomp;
2141                         ostate = ppp->xc_state;
2142                         ppp->xcomp = cp;
2143                         ppp->xc_state = state;
2144                         ppp_xmit_unlock(ppp);
2145                         if (ostate) {
2146                                 ocomp->comp_free(ostate);
2147                                 module_put(ocomp->owner);
2148                         }
2149                         err = 0;
2150                 } else
2151                         module_put(cp->owner);
2152
2153         } else {
2154                 state = cp->decomp_alloc(ccp_option, data.length);
2155                 if (state) {
2156                         ppp_recv_lock(ppp);
2157                         ppp->rstate &= ~SC_DECOMP_RUN;
2158                         ocomp = ppp->rcomp;
2159                         ostate = ppp->rc_state;
2160                         ppp->rcomp = cp;
2161                         ppp->rc_state = state;
2162                         ppp_recv_unlock(ppp);
2163                         if (ostate) {
2164                                 ocomp->decomp_free(ostate);
2165                                 module_put(ocomp->owner);
2166                         }
2167                         err = 0;
2168                 } else
2169                         module_put(cp->owner);
2170         }
2171
2172  out:
2173         return err;
2174 }
2175
2176 /*
2177  * Look at a CCP packet and update our state accordingly.
2178  * We assume the caller has the xmit or recv path locked.
2179  */
2180 static void
2181 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2182 {
2183         unsigned char *dp;
2184         int len;
2185
2186         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2187                 return; /* no header */
2188         dp = skb->data + 2;
2189
2190         switch (CCP_CODE(dp)) {
2191         case CCP_CONFREQ:
2192
2193                 /* A ConfReq starts negotiation of compression
2194                  * in one direction of transmission,
2195                  * and hence brings it down...but which way?
2196                  *
2197                  * Remember:
2198                  * A ConfReq indicates what the sender would like to receive
2199                  */
2200                 if(inbound)
2201                         /* He is proposing what I should send */
2202                         ppp->xstate &= ~SC_COMP_RUN;
2203                 else
2204                         /* I am proposing to what he should send */
2205                         ppp->rstate &= ~SC_DECOMP_RUN;
2206
2207                 break;
2208
2209         case CCP_TERMREQ:
2210         case CCP_TERMACK:
2211                 /*
2212                  * CCP is going down, both directions of transmission
2213                  */
2214                 ppp->rstate &= ~SC_DECOMP_RUN;
2215                 ppp->xstate &= ~SC_COMP_RUN;
2216                 break;
2217
2218         case CCP_CONFACK:
2219                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2220                         break;
2221                 len = CCP_LENGTH(dp);
2222                 if (!pskb_may_pull(skb, len + 2))
2223                         return;         /* too short */
2224                 dp += CCP_HDRLEN;
2225                 len -= CCP_HDRLEN;
2226                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2227                         break;
2228                 if (inbound) {
2229                         /* we will start receiving compressed packets */
2230                         if (!ppp->rc_state)
2231                                 break;
2232                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2233                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2234                                 ppp->rstate |= SC_DECOMP_RUN;
2235                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2236                         }
2237                 } else {
2238                         /* we will soon start sending compressed packets */
2239                         if (!ppp->xc_state)
2240                                 break;
2241                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2242                                         ppp->file.index, 0, ppp->debug))
2243                                 ppp->xstate |= SC_COMP_RUN;
2244                 }
2245                 break;
2246
2247         case CCP_RESETACK:
2248                 /* reset the [de]compressor */
2249                 if ((ppp->flags & SC_CCP_UP) == 0)
2250                         break;
2251                 if (inbound) {
2252                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2253                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2254                                 ppp->rstate &= ~SC_DC_ERROR;
2255                         }
2256                 } else {
2257                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2258                                 ppp->xcomp->comp_reset(ppp->xc_state);
2259                 }
2260                 break;
2261         }
2262 }
2263
2264 /* Free up compression resources. */
2265 static void
2266 ppp_ccp_closed(struct ppp *ppp)
2267 {
2268         void *xstate, *rstate;
2269         struct compressor *xcomp, *rcomp;
2270
2271         ppp_lock(ppp);
2272         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2273         ppp->xstate = 0;
2274         xcomp = ppp->xcomp;
2275         xstate = ppp->xc_state;
2276         ppp->xc_state = NULL;
2277         ppp->rstate = 0;
2278         rcomp = ppp->rcomp;
2279         rstate = ppp->rc_state;
2280         ppp->rc_state = NULL;
2281         ppp_unlock(ppp);
2282
2283         if (xstate) {
2284                 xcomp->comp_free(xstate);
2285                 module_put(xcomp->owner);
2286         }
2287         if (rstate) {
2288                 rcomp->decomp_free(rstate);
2289                 module_put(rcomp->owner);
2290         }
2291 }
2292
2293 /* List of compressors. */
2294 static LIST_HEAD(compressor_list);
2295 static DEFINE_SPINLOCK(compressor_list_lock);
2296
2297 struct compressor_entry {
2298         struct list_head list;
2299         struct compressor *comp;
2300 };
2301
2302 static struct compressor_entry *
2303 find_comp_entry(int proto)
2304 {
2305         struct compressor_entry *ce;
2306
2307         list_for_each_entry(ce, &compressor_list, list) {
2308                 if (ce->comp->compress_proto == proto)
2309                         return ce;
2310         }
2311         return NULL;
2312 }
2313
2314 /* Register a compressor */
2315 int
2316 ppp_register_compressor(struct compressor *cp)
2317 {
2318         struct compressor_entry *ce;
2319         int ret;
2320         spin_lock(&compressor_list_lock);
2321         ret = -EEXIST;
2322         if (find_comp_entry(cp->compress_proto))
2323                 goto out;
2324         ret = -ENOMEM;
2325         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2326         if (!ce)
2327                 goto out;
2328         ret = 0;
2329         ce->comp = cp;
2330         list_add(&ce->list, &compressor_list);
2331  out:
2332         spin_unlock(&compressor_list_lock);
2333         return ret;
2334 }
2335
2336 /* Unregister a compressor */
2337 void
2338 ppp_unregister_compressor(struct compressor *cp)
2339 {
2340         struct compressor_entry *ce;
2341
2342         spin_lock(&compressor_list_lock);
2343         ce = find_comp_entry(cp->compress_proto);
2344         if (ce && ce->comp == cp) {
2345                 list_del(&ce->list);
2346                 kfree(ce);
2347         }
2348         spin_unlock(&compressor_list_lock);
2349 }
2350
2351 /* Find a compressor. */
2352 static struct compressor *
2353 find_compressor(int type)
2354 {
2355         struct compressor_entry *ce;
2356         struct compressor *cp = NULL;
2357
2358         spin_lock(&compressor_list_lock);
2359         ce = find_comp_entry(type);
2360         if (ce) {
2361                 cp = ce->comp;
2362                 if (!try_module_get(cp->owner))
2363                         cp = NULL;
2364         }
2365         spin_unlock(&compressor_list_lock);
2366         return cp;
2367 }
2368
2369 /*
2370  * Miscelleneous stuff.
2371  */
2372
2373 static void
2374 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2375 {
2376         struct slcompress *vj = ppp->vj;
2377
2378         memset(st, 0, sizeof(*st));
2379         st->p.ppp_ipackets = ppp->dev->stats.rx_packets;
2380         st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2381         st->p.ppp_ibytes = ppp->dev->stats.rx_bytes;
2382         st->p.ppp_opackets = ppp->dev->stats.tx_packets;
2383         st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2384         st->p.ppp_obytes = ppp->dev->stats.tx_bytes;
2385         if (!vj)
2386                 return;
2387         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2388         st->vj.vjs_compressed = vj->sls_o_compressed;
2389         st->vj.vjs_searches = vj->sls_o_searches;
2390         st->vj.vjs_misses = vj->sls_o_misses;
2391         st->vj.vjs_errorin = vj->sls_i_error;
2392         st->vj.vjs_tossed = vj->sls_i_tossed;
2393         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2394         st->vj.vjs_compressedin = vj->sls_i_compressed;
2395 }
2396
2397 /*
2398  * Stuff for handling the lists of ppp units and channels
2399  * and for initialization.
2400  */
2401
2402 /*
2403  * Create a new ppp interface unit.  Fails if it can't allocate memory
2404  * or if there is already a unit with the requested number.
2405  * unit == -1 means allocate a new number.
2406  */
2407 static struct ppp *
2408 ppp_create_interface(int unit, int *retp)
2409 {
2410         struct ppp *ppp;
2411         struct net_device *dev = NULL;
2412         int ret = -ENOMEM;
2413         int i;
2414
2415         ppp = kzalloc(sizeof(struct ppp), GFP_KERNEL);
2416         if (!ppp)
2417                 goto out;
2418         dev = alloc_netdev(0, "", ppp_setup);
2419         if (!dev)
2420                 goto out1;
2421
2422         ppp->mru = PPP_MRU;
2423         init_ppp_file(&ppp->file, INTERFACE);
2424         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2425         for (i = 0; i < NUM_NP; ++i)
2426                 ppp->npmode[i] = NPMODE_PASS;
2427         INIT_LIST_HEAD(&ppp->channels);
2428         spin_lock_init(&ppp->rlock);
2429         spin_lock_init(&ppp->wlock);
2430 #ifdef CONFIG_PPP_MULTILINK
2431         ppp->minseq = -1;
2432         skb_queue_head_init(&ppp->mrq);
2433 #endif /* CONFIG_PPP_MULTILINK */
2434         ppp->dev = dev;
2435         dev->priv = ppp;
2436
2437         dev->hard_start_xmit = ppp_start_xmit;
2438         dev->do_ioctl = ppp_net_ioctl;
2439
2440         ret = -EEXIST;
2441         mutex_lock(&all_ppp_mutex);
2442         if (unit < 0)
2443                 unit = cardmap_find_first_free(all_ppp_units);
2444         else if (cardmap_get(all_ppp_units, unit) != NULL)
2445                 goto out2;      /* unit already exists */
2446
2447         /* Initialize the new ppp unit */
2448         ppp->file.index = unit;
2449         sprintf(dev->name, "ppp%d", unit);
2450
2451         ret = register_netdev(dev);
2452         if (ret != 0) {
2453                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2454                        dev->name, ret);
2455                 goto out2;
2456         }
2457
2458         atomic_inc(&ppp_unit_count);
2459         ret = cardmap_set(&all_ppp_units, unit, ppp);
2460         if (ret != 0)
2461                 goto out3;
2462
2463         mutex_unlock(&all_ppp_mutex);
2464         *retp = 0;
2465         return ppp;
2466
2467 out3:
2468         atomic_dec(&ppp_unit_count);
2469         unregister_netdev(dev);
2470 out2:
2471         mutex_unlock(&all_ppp_mutex);
2472         free_netdev(dev);
2473 out1:
2474         kfree(ppp);
2475 out:
2476         *retp = ret;
2477         return NULL;
2478 }
2479
2480 /*
2481  * Initialize a ppp_file structure.
2482  */
2483 static void
2484 init_ppp_file(struct ppp_file *pf, int kind)
2485 {
2486         pf->kind = kind;
2487         skb_queue_head_init(&pf->xq);
2488         skb_queue_head_init(&pf->rq);
2489         atomic_set(&pf->refcnt, 1);
2490         init_waitqueue_head(&pf->rwait);
2491 }
2492
2493 /*
2494  * Take down a ppp interface unit - called when the owning file
2495  * (the one that created the unit) is closed or detached.
2496  */
2497 static void ppp_shutdown_interface(struct ppp *ppp)
2498 {
2499         struct net_device *dev;
2500
2501         mutex_lock(&all_ppp_mutex);
2502         ppp_lock(ppp);
2503         dev = ppp->dev;
2504         ppp->dev = NULL;
2505         ppp_unlock(ppp);
2506         /* This will call dev_close() for us. */
2507         if (dev) {
2508                 unregister_netdev(dev);
2509                 free_netdev(dev);
2510         }
2511         cardmap_set(&all_ppp_units, ppp->file.index, NULL);
2512         ppp->file.dead = 1;
2513         ppp->owner = NULL;
2514         wake_up_interruptible(&ppp->file.rwait);
2515         mutex_unlock(&all_ppp_mutex);
2516 }
2517
2518 /*
2519  * Free the memory used by a ppp unit.  This is only called once
2520  * there are no channels connected to the unit and no file structs
2521  * that reference the unit.
2522  */
2523 static void ppp_destroy_interface(struct ppp *ppp)
2524 {
2525         atomic_dec(&ppp_unit_count);
2526
2527         if (!ppp->file.dead || ppp->n_channels) {
2528                 /* "can't happen" */
2529                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2530                        "n_channels=%d !\n", ppp, ppp->file.dead,
2531                        ppp->n_channels);
2532                 return;
2533         }
2534
2535         ppp_ccp_closed(ppp);
2536         if (ppp->vj) {
2537                 slhc_free(ppp->vj);
2538                 ppp->vj = NULL;
2539         }
2540         skb_queue_purge(&ppp->file.xq);
2541         skb_queue_purge(&ppp->file.rq);
2542 #ifdef CONFIG_PPP_MULTILINK
2543         skb_queue_purge(&ppp->mrq);
2544 #endif /* CONFIG_PPP_MULTILINK */
2545 #ifdef CONFIG_PPP_FILTER
2546         kfree(ppp->pass_filter);
2547         ppp->pass_filter = NULL;
2548         kfree(ppp->active_filter);
2549         ppp->active_filter = NULL;
2550 #endif /* CONFIG_PPP_FILTER */
2551
2552         if (ppp->xmit_pending)
2553                 kfree_skb(ppp->xmit_pending);
2554
2555         kfree(ppp);
2556 }
2557
2558 /*
2559  * Locate an existing ppp unit.
2560  * The caller should have locked the all_ppp_mutex.
2561  */
2562 static struct ppp *
2563 ppp_find_unit(int unit)
2564 {
2565         return cardmap_get(all_ppp_units, unit);
2566 }
2567
2568 /*
2569  * Locate an existing ppp channel.
2570  * The caller should have locked the all_channels_lock.
2571  * First we look in the new_channels list, then in the
2572  * all_channels list.  If found in the new_channels list,
2573  * we move it to the all_channels list.  This is for speed
2574  * when we have a lot of channels in use.
2575  */
2576 static struct channel *
2577 ppp_find_channel(int unit)
2578 {
2579         struct channel *pch;
2580
2581         list_for_each_entry(pch, &new_channels, list) {
2582                 if (pch->file.index == unit) {
2583                         list_move(&pch->list, &all_channels);
2584                         return pch;
2585                 }
2586         }
2587         list_for_each_entry(pch, &all_channels, list) {
2588                 if (pch->file.index == unit)
2589                         return pch;
2590         }
2591         return NULL;
2592 }
2593
2594 /*
2595  * Connect a PPP channel to a PPP interface unit.
2596  */
2597 static int
2598 ppp_connect_channel(struct channel *pch, int unit)
2599 {
2600         struct ppp *ppp;
2601         int ret = -ENXIO;
2602         int hdrlen;
2603
2604         mutex_lock(&all_ppp_mutex);
2605         ppp = ppp_find_unit(unit);
2606         if (!ppp)
2607                 goto out;
2608         write_lock_bh(&pch->upl);
2609         ret = -EINVAL;
2610         if (pch->ppp)
2611                 goto outl;
2612
2613         ppp_lock(ppp);
2614         if (pch->file.hdrlen > ppp->file.hdrlen)
2615                 ppp->file.hdrlen = pch->file.hdrlen;
2616         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2617         if (ppp->dev && hdrlen > ppp->dev->hard_header_len)
2618                 ppp->dev->hard_header_len = hdrlen;
2619         list_add_tail(&pch->clist, &ppp->channels);
2620         ++ppp->n_channels;
2621         pch->ppp = ppp;
2622         atomic_inc(&ppp->file.refcnt);
2623         ppp_unlock(ppp);
2624         ret = 0;
2625
2626  outl:
2627         write_unlock_bh(&pch->upl);
2628  out:
2629         mutex_unlock(&all_ppp_mutex);
2630         return ret;
2631 }
2632
2633 /*
2634  * Disconnect a channel from its ppp unit.
2635  */
2636 static int
2637 ppp_disconnect_channel(struct channel *pch)
2638 {
2639         struct ppp *ppp;
2640         int err = -EINVAL;
2641
2642         write_lock_bh(&pch->upl);
2643         ppp = pch->ppp;
2644         pch->ppp = NULL;
2645         write_unlock_bh(&pch->upl);
2646         if (ppp) {
2647                 /* remove it from the ppp unit's list */
2648                 ppp_lock(ppp);
2649                 list_del(&pch->clist);
2650                 if (--ppp->n_channels == 0)
2651                         wake_up_interruptible(&ppp->file.rwait);
2652                 ppp_unlock(ppp);
2653                 if (atomic_dec_and_test(&ppp->file.refcnt))
2654                         ppp_destroy_interface(ppp);
2655                 err = 0;
2656         }
2657         return err;
2658 }
2659
2660 /*
2661  * Free up the resources used by a ppp channel.
2662  */
2663 static void ppp_destroy_channel(struct channel *pch)
2664 {
2665         atomic_dec(&channel_count);
2666
2667         if (!pch->file.dead) {
2668                 /* "can't happen" */
2669                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2670                        pch);
2671                 return;
2672         }
2673         skb_queue_purge(&pch->file.xq);
2674         skb_queue_purge(&pch->file.rq);
2675         kfree(pch);
2676 }
2677
2678 static void __exit ppp_cleanup(void)
2679 {
2680         /* should never happen */
2681         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2682                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2683         cardmap_destroy(&all_ppp_units);
2684         unregister_chrdev(PPP_MAJOR, "ppp");
2685         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2686         class_destroy(ppp_class);
2687 }
2688
2689 /*
2690  * Cardmap implementation.
2691  */
2692 static void *cardmap_get(struct cardmap *map, unsigned int nr)
2693 {
2694         struct cardmap *p;
2695         int i;
2696
2697         for (p = map; p != NULL; ) {
2698                 if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
2699                         return NULL;
2700                 if (p->shift == 0)
2701                         return p->ptr[i];
2702                 nr &= ~(CARDMAP_MASK << p->shift);
2703                 p = p->ptr[i];
2704         }
2705         return NULL;
2706 }
2707
2708 static int cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
2709 {
2710         struct cardmap *p;
2711         int i;
2712
2713         p = *pmap;
2714         if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
2715                 do {
2716                         /* need a new top level */
2717                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2718                         if (!np)
2719                                 goto enomem;
2720                         np->ptr[0] = p;
2721                         if (p != NULL) {
2722                                 np->shift = p->shift + CARDMAP_ORDER;
2723                                 p->parent = np;
2724                         } else
2725                                 np->shift = 0;
2726                         p = np;
2727                 } while ((nr >> p->shift) >= CARDMAP_WIDTH);
2728                 *pmap = p;
2729         }
2730         while (p->shift > 0) {
2731                 i = (nr >> p->shift) & CARDMAP_MASK;
2732                 if (p->ptr[i] == NULL) {
2733                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2734                         if (!np)
2735                                 goto enomem;
2736                         np->shift = p->shift - CARDMAP_ORDER;
2737                         np->parent = p;
2738                         p->ptr[i] = np;
2739                 }
2740                 if (ptr == NULL)
2741                         clear_bit(i, &p->inuse);
2742                 p = p->ptr[i];
2743         }
2744         i = nr & CARDMAP_MASK;
2745         p->ptr[i] = ptr;
2746         if (ptr != NULL)
2747                 set_bit(i, &p->inuse);
2748         else
2749                 clear_bit(i, &p->inuse);
2750         return 0;
2751  enomem:
2752         return -ENOMEM;
2753 }
2754
2755 static unsigned int cardmap_find_first_free(struct cardmap *map)
2756 {
2757         struct cardmap *p;
2758         unsigned int nr = 0;
2759         int i;
2760
2761         if ((p = map) == NULL)
2762                 return 0;
2763         for (;;) {
2764                 i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
2765                 if (i >= CARDMAP_WIDTH) {
2766                         if (p->parent == NULL)
2767                                 return CARDMAP_WIDTH << p->shift;
2768                         p = p->parent;
2769                         i = (nr >> p->shift) & CARDMAP_MASK;
2770                         set_bit(i, &p->inuse);
2771                         continue;
2772                 }
2773                 nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
2774                 if (p->shift == 0 || p->ptr[i] == NULL)
2775                         return nr;
2776                 p = p->ptr[i];
2777         }
2778 }
2779
2780 static void cardmap_destroy(struct cardmap **pmap)
2781 {
2782         struct cardmap *p, *np;
2783         int i;
2784
2785         for (p = *pmap; p != NULL; p = np) {
2786                 if (p->shift != 0) {
2787                         for (i = 0; i < CARDMAP_WIDTH; ++i)
2788                                 if (p->ptr[i] != NULL)
2789                                         break;
2790                         if (i < CARDMAP_WIDTH) {
2791                                 np = p->ptr[i];
2792                                 p->ptr[i] = NULL;
2793                                 continue;
2794                         }
2795                 }
2796                 np = p->parent;
2797                 kfree(p);
2798         }
2799         *pmap = NULL;
2800 }
2801
2802 /* Module/initialization stuff */
2803
2804 module_init(ppp_init);
2805 module_exit(ppp_cleanup);
2806
2807 EXPORT_SYMBOL(ppp_register_channel);
2808 EXPORT_SYMBOL(ppp_unregister_channel);
2809 EXPORT_SYMBOL(ppp_channel_index);
2810 EXPORT_SYMBOL(ppp_unit_number);
2811 EXPORT_SYMBOL(ppp_input);
2812 EXPORT_SYMBOL(ppp_input_error);
2813 EXPORT_SYMBOL(ppp_output_wakeup);
2814 EXPORT_SYMBOL(ppp_register_compressor);
2815 EXPORT_SYMBOL(ppp_unregister_compressor);
2816 MODULE_LICENSE("GPL");
2817 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2818 MODULE_ALIAS("/dev/ppp");