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         struct net_device_stats stats;  /* statistics */
 127 #ifdef CONFIG_PPP_FILTER
 128         struct sock_filter *pass_filter;        /* filter for packets to pass */
 129         struct sock_filter *active_filter;/* filter for pkts to reset idle */
 130         unsigned pass_len, active_len;
 131 #endif /* CONFIG_PPP_FILTER */
 132 };
 133
 134 /*
 135  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
 136  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
 137  * SC_MUST_COMP
 138  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
 139  * Bits in xstate: SC_COMP_RUN
 140  */
 141 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
 142                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
 143                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
 144
 145 /*
 146  * Private data structure for each channel.
 147  * This includes the data structure used for multilink.
 148  */
 149 struct channel {
 150         struct ppp_file file;           /* stuff for read/write/poll */
 151         struct list_head list;          /* link in all/new_channels list */
 152         struct ppp_channel *chan;       /* public channel data structure */
 153         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
 154         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
 155         struct ppp      *ppp;           /* ppp unit we're connected to */
 156         struct list_head clist;         /* link in list of channels per unit */
 157         rwlock_t        upl;            /* protects `ppp' */
 158 #ifdef CONFIG_PPP_MULTILINK
 159         u8              avail;          /* flag used in multilink stuff */
 160         u8              had_frag;       /* >= 1 fragments have been sent */
 161         u32             lastseq;        /* MP: last sequence # received */
 162 #endif /* CONFIG_PPP_MULTILINK */
 163 };
 164
 165 /*
 166  * SMP locking issues:
 167  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
 168  * list and the ppp.n_channels field, you need to take both locks
 169  * before you modify them.
 170  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
 171  * channel.downl.
 172  */
 173
 174 /*
 175  * A cardmap represents a mapping from unsigned integers to pointers,
 176  * and provides a fast "find lowest unused number" operation.
 177  * It uses a broad (32-way) tree with a bitmap at each level.
 178  * It is designed to be space-efficient for small numbers of entries
 179  * and time-efficient for large numbers of entries.
 180  */
 181 #define CARDMAP_ORDER   5
 182 #define CARDMAP_WIDTH   (1U << CARDMAP_ORDER)
 183 #define CARDMAP_MASK    (CARDMAP_WIDTH - 1)
 184
 185 struct cardmap {
 186         int shift;
 187         unsigned long inuse;
 188         struct cardmap *parent;
 189         void *ptr[CARDMAP_WIDTH];
 190 };
 191 static void *cardmap_get(struct cardmap *map, unsigned int nr);
 192 static int cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
 193 static unsigned int cardmap_find_first_free(struct cardmap *map);
 194 static void cardmap_destroy(struct cardmap **map);
 195
 196 /*
 197  * all_ppp_mutex protects the all_ppp_units mapping.
 198  * It also ensures that finding a ppp unit in the all_ppp_units map
 199  * and updating its file.refcnt field is atomic.
 200  */
 201 static DEFINE_MUTEX(all_ppp_mutex);
 202 static struct cardmap *all_ppp_units;
 203 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 204
 205 /*
 206  * all_channels_lock protects all_channels and last_channel_index,
 207  * and the atomicity of find a channel and updating its file.refcnt
 208  * field.
 209  */
 210 static DEFINE_SPINLOCK(all_channels_lock);
 211 static LIST_HEAD(all_channels);
 212 static LIST_HEAD(new_channels);
 213 static int last_channel_index;
 214 static atomic_t channel_count = ATOMIC_INIT(0);
 215
 216 /* Get the PPP protocol number from a skb */
 217 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
 218
 219 /* We limit the length of ppp->file.rq to this (arbitrary) value */
 220 #define PPP_MAX_RQLEN   32
 221
 222 /*
 223  * Maximum number of multilink fragments queued up.
 224  * This has to be large enough to cope with the maximum latency of
 225  * the slowest channel relative to the others.  Strictly it should
 226  * depend on the number of channels and their characteristics.
 227  */
 228 #define PPP_MP_MAX_QLEN 128
 229
 230 /* Multilink header bits. */
 231 #define B       0x80            /* this fragment begins a packet */
 232 #define E       0x40            /* this fragment ends a packet */
 233
 234 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
 235 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
 236 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
 237
 238 /* Prototypes. */
 239 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 240                                 unsigned int cmd, unsigned long arg);
 241 static void ppp_xmit_process(struct ppp *ppp);
 242 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
 243 static void ppp_push(struct ppp *ppp);
 244 static void ppp_channel_push(struct channel *pch);
 245 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
 246                               struct channel *pch);
 247 static void ppp_receive_error(struct ppp *ppp);
 248 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
 249 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
 250                                             struct sk_buff *skb);
 251 #ifdef CONFIG_PPP_MULTILINK
 252 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
 253                                 struct channel *pch);
 254 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
 255 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
 256 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
 257 #endif /* CONFIG_PPP_MULTILINK */
 258 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
 259 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
 260 static void ppp_ccp_closed(struct ppp *ppp);
 261 static struct compressor *find_compressor(int type);
 262 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
 263 static struct ppp *ppp_create_interface(int unit, int *retp);
 264 static void init_ppp_file(struct ppp_file *pf, int kind);
 265 static void ppp_shutdown_interface(struct ppp *ppp);
 266 static void ppp_destroy_interface(struct ppp *ppp);
 267 static struct ppp *ppp_find_unit(int unit);
 268 static struct channel *ppp_find_channel(int unit);
 269 static int ppp_connect_channel(struct channel *pch, int unit);
 270 static int ppp_disconnect_channel(struct channel *pch);
 271 static void ppp_destroy_channel(struct channel *pch);
 272
 273 static struct class *ppp_class;
 274
 275 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
 276 static inline int proto_to_npindex(int proto)
 277 {
 278         switch (proto) {
 279         case PPP_IP:
 280                 return NP_IP;
 281         case PPP_IPV6:
 282                 return NP_IPV6;
 283         case PPP_IPX:
 284                 return NP_IPX;
 285         case PPP_AT:
 286                 return NP_AT;
 287         case PPP_MPLS_UC:
 288                 return NP_MPLS_UC;
 289         case PPP_MPLS_MC:
 290                 return NP_MPLS_MC;
 291         }
 292         return -EINVAL;
 293 }
 294
 295 /* Translates an NP index into a PPP protocol number */
 296 static const int npindex_to_proto[NUM_NP] = {
 297         PPP_IP,
 298         PPP_IPV6,
 299         PPP_IPX,
 300         PPP_AT,
 301         PPP_MPLS_UC,
 302         PPP_MPLS_MC,
 303 };
 304
 305 /* Translates an ethertype into an NP index */
 306 static inline int ethertype_to_npindex(int ethertype)
 307 {
 308         switch (ethertype) {
 309         case ETH_P_IP:
 310                 return NP_IP;
 311         case ETH_P_IPV6:
 312                 return NP_IPV6;
 313         case ETH_P_IPX:
 314                 return NP_IPX;
 315         case ETH_P_PPPTALK:
 316         case ETH_P_ATALK:
 317                 return NP_AT;
 318         case ETH_P_MPLS_UC:
 319                 return NP_MPLS_UC;
 320         case ETH_P_MPLS_MC:
 321                 return NP_MPLS_MC;
 322         }
 323         return -1;
 324 }
 325
 326 /* Translates an NP index into an ethertype */
 327 static const int npindex_to_ethertype[NUM_NP] = {
 328         ETH_P_IP,
 329         ETH_P_IPV6,
 330         ETH_P_IPX,
 331         ETH_P_PPPTALK,
 332         ETH_P_MPLS_UC,
 333         ETH_P_MPLS_MC,
 334 };
 335
 336 /*
 337  * Locking shorthand.
 338  */
 339 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
 340 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
 341 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
 342 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
 343 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
 344                                      ppp_recv_lock(ppp); } while (0)
 345 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
 346                                      ppp_xmit_unlock(ppp); } while (0)
 347
 348 /*
 349  * /dev/ppp device routines.
 350  * The /dev/ppp device is used by pppd to control the ppp unit.
 351  * It supports the read, write, ioctl and poll functions.
 352  * Open instances of /dev/ppp can be in one of three states:
 353  * unattached, attached to a ppp unit, or attached to a ppp channel.
 354  */
 355 static int ppp_open(struct inode *inode, struct file *file)
 356 {
 357         /*
 358          * This could (should?) be enforced by the permissions on /dev/ppp.
 359          */
 360         if (!capable(CAP_NET_ADMIN))
 361                 return -EPERM;
 362         return 0;
 363 }
 364
 365 static int ppp_release(struct inode *inode, struct file *file)
 366 {
 367         struct ppp_file *pf = file->private_data;
 368         struct ppp *ppp;
 369
 370         if (pf != 0) {
 371                 file->private_data = NULL;
 372                 if (pf->kind == INTERFACE) {
 373                         ppp = PF_TO_PPP(pf);
 374                         if (file == ppp->owner)
 375                                 ppp_shutdown_interface(ppp);
 376                 }
 377                 if (atomic_dec_and_test(&pf->refcnt)) {
 378                         switch (pf->kind) {
 379                         case INTERFACE:
 380                                 ppp_destroy_interface(PF_TO_PPP(pf));
 381                                 break;
 382                         case CHANNEL:
 383                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
 384                                 break;
 385                         }
 386                 }
 387         }
 388         return 0;
 389 }
 390
 391 static ssize_t ppp_read(struct file *file, char __user *buf,
 392                         size_t count, loff_t *ppos)
 393 {
 394         struct ppp_file *pf = file->private_data;
 395         DECLARE_WAITQUEUE(wait, current);
 396         ssize_t ret;
 397         struct sk_buff *skb = NULL;
 398
 399         ret = count;
 400
 401         if (pf == 0)
 402                 return -ENXIO;
 403         add_wait_queue(&pf->rwait, &wait);
 404         for (;;) {
 405                 set_current_state(TASK_INTERRUPTIBLE);
 406                 skb = skb_dequeue(&pf->rq);
 407                 if (skb)
 408                         break;
 409                 ret = 0;
 410                 if (pf->dead)
 411                         break;
 412                 if (pf->kind == INTERFACE) {
 413                         /*
 414                          * Return 0 (EOF) on an interface that has no
 415                          * channels connected, unless it is looping
 416                          * network traffic (demand mode).
 417                          */
 418                         struct ppp *ppp = PF_TO_PPP(pf);
 419                         if (ppp->n_channels == 0
 420                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 421                                 break;
 422                 }
 423                 ret = -EAGAIN;
 424                 if (file->f_flags & O_NONBLOCK)
 425                         break;
 426                 ret = -ERESTARTSYS;
 427                 if (signal_pending(current))
 428                         break;
 429                 schedule();
 430         }
 431         set_current_state(TASK_RUNNING);
 432         remove_wait_queue(&pf->rwait, &wait);
 433
 434         if (skb == 0)
 435                 goto out;
 436
 437         ret = -EOVERFLOW;
 438         if (skb->len > count)
 439                 goto outf;
 440         ret = -EFAULT;
 441         if (copy_to_user(buf, skb->data, skb->len))
 442                 goto outf;
 443         ret = skb->len;
 444
 445  outf:
 446         kfree_skb(skb);
 447  out:
 448         return ret;
 449 }
 450
 451 static ssize_t ppp_write(struct file *file, const char __user *buf,
 452                          size_t count, loff_t *ppos)
 453 {
 454         struct ppp_file *pf = file->private_data;
 455         struct sk_buff *skb;
 456         ssize_t ret;
 457
 458         if (pf == 0)
 459                 return -ENXIO;
 460         ret = -ENOMEM;
 461         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
 462         if (skb == 0)
 463                 goto out;
 464         skb_reserve(skb, pf->hdrlen);
 465         ret = -EFAULT;
 466         if (copy_from_user(skb_put(skb, count), buf, count)) {
 467                 kfree_skb(skb);
 468                 goto out;
 469         }
 470
 471         skb_queue_tail(&pf->xq, skb);
 472
 473         switch (pf->kind) {
 474         case INTERFACE:
 475                 ppp_xmit_process(PF_TO_PPP(pf));
 476                 break;
 477         case CHANNEL:
 478                 ppp_channel_push(PF_TO_CHANNEL(pf));
 479                 break;
 480         }
 481
 482         ret = count;
 483
 484  out:
 485         return ret;
 486 }
 487
 488 /* No kernel lock - fine */
 489 static unsigned int ppp_poll(struct file *file, poll_table *wait)
 490 {
 491         struct ppp_file *pf = file->private_data;
 492         unsigned int mask;
 493
 494         if (pf == 0)
 495                 return 0;
 496         poll_wait(file, &pf->rwait, wait);
 497         mask = POLLOUT | POLLWRNORM;
 498         if (skb_peek(&pf->rq) != 0)
 499                 mask |= POLLIN | POLLRDNORM;
 500         if (pf->dead)
 501                 mask |= POLLHUP;
 502         else if (pf->kind == INTERFACE) {
 503                 /* see comment in ppp_read */
 504                 struct ppp *ppp = PF_TO_PPP(pf);
 505                 if (ppp->n_channels == 0
 506                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 507                         mask |= POLLIN | POLLRDNORM;
 508         }
 509
 510         return mask;
 511 }
 512
 513 #ifdef CONFIG_PPP_FILTER
 514 static int get_filter(void __user *arg, struct sock_filter **p)
 515 {
 516         struct sock_fprog uprog;
 517         struct sock_filter *code = NULL;
 518         int len, err;
 519
 520         if (copy_from_user(&uprog, arg, sizeof(uprog)))
 521                 return -EFAULT;
 522
 523         if (!uprog.len) {
 524                 *p = NULL;
 525                 return 0;
 526         }
 527
 528         len = uprog.len * sizeof(struct sock_filter);
 529         code = kmalloc(len, GFP_KERNEL);
 530         if (code == NULL)
 531                 return -ENOMEM;
 532
 533         if (copy_from_user(code, uprog.filter, len)) {
 534                 kfree(code);
 535                 return -EFAULT;
 536         }
 537
 538         err = sk_chk_filter(code, uprog.len);
 539         if (err) {
 540                 kfree(code);
 541                 return err;
 542         }
 543
 544         *p = code;
 545         return uprog.len;
 546 }
 547 #endif /* CONFIG_PPP_FILTER */
 548
 549 static int ppp_ioctl(struct inode *inode, struct file *file,
 550                      unsigned int cmd, unsigned long arg)
 551 {
 552         struct ppp_file *pf = file->private_data;
 553         struct ppp *ppp;
 554         int err = -EFAULT, val, val2, i;
 555         struct ppp_idle idle;
 556         struct npioctl npi;
 557         int unit, cflags;
 558         struct slcompress *vj;
 559         void __user *argp = (void __user *)arg;
 560         int __user *p = argp;
 561
 562         if (pf == 0)
 563                 return ppp_unattached_ioctl(pf, file, cmd, arg);
 564
 565         if (cmd == PPPIOCDETACH) {
 566                 /*
 567                  * We have to be careful here... if the file descriptor
 568                  * has been dup'd, we could have another process in the
 569                  * middle of a poll using the same file *, so we had
 570                  * better not free the interface data structures -
 571                  * instead we fail the ioctl.  Even in this case, we
 572                  * shut down the interface if we are the owner of it.
 573                  * Actually, we should get rid of PPPIOCDETACH, userland
 574                  * (i.e. pppd) could achieve the same effect by closing
 575                  * this fd and reopening /dev/ppp.
 576                  */
 577                 err = -EINVAL;
 578                 if (pf->kind == INTERFACE) {
 579                         ppp = PF_TO_PPP(pf);
 580                         if (file == ppp->owner)
 581                                 ppp_shutdown_interface(ppp);
 582                 }
 583                 if (atomic_read(&file->f_count) <= 2) {
 584                         ppp_release(inode, file);
 585                         err = 0;
 586                 } else
 587                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%d\n",
 588                                atomic_read(&file->f_count));
 589                 return err;
 590         }
 591
 592         if (pf->kind == CHANNEL) {
 593                 struct channel *pch = PF_TO_CHANNEL(pf);
 594                 struct ppp_channel *chan;
 595
 596                 switch (cmd) {
 597                 case PPPIOCCONNECT:
 598                         if (get_user(unit, p))
 599                                 break;
 600                         err = ppp_connect_channel(pch, unit);
 601                         break;
 602
 603                 case PPPIOCDISCONN:
 604                         err = ppp_disconnect_channel(pch);
 605                         break;
 606
 607                 default:
 608                         down_read(&pch->chan_sem);
 609                         chan = pch->chan;
 610                         err = -ENOTTY;
 611                         if (chan && chan->ops->ioctl)
 612                                 err = chan->ops->ioctl(chan, cmd, arg);
 613                         up_read(&pch->chan_sem);
 614                 }
 615                 return err;
 616         }
 617
 618         if (pf->kind != INTERFACE) {
 619                 /* can't happen */
 620                 printk(KERN_ERR "PPP: not interface or channel??\n");
 621                 return -EINVAL;
 622         }
 623
 624         ppp = PF_TO_PPP(pf);
 625         switch (cmd) {
 626         case PPPIOCSMRU:
 627                 if (get_user(val, p))
 628                         break;
 629                 ppp->mru = val;
 630                 err = 0;
 631                 break;
 632
 633         case PPPIOCSFLAGS:
 634                 if (get_user(val, p))
 635                         break;
 636                 ppp_lock(ppp);
 637                 cflags = ppp->flags & ~val;
 638                 ppp->flags = val & SC_FLAG_BITS;
 639                 ppp_unlock(ppp);
 640                 if (cflags & SC_CCP_OPEN)
 641                         ppp_ccp_closed(ppp);
 642                 err = 0;
 643                 break;
 644
 645         case PPPIOCGFLAGS:
 646                 val = ppp->flags | ppp->xstate | ppp->rstate;
 647                 if (put_user(val, p))
 648                         break;
 649                 err = 0;
 650                 break;
 651
 652         case PPPIOCSCOMPRESS:
 653                 err = ppp_set_compress(ppp, arg);
 654                 break;
 655
 656         case PPPIOCGUNIT:
 657                 if (put_user(ppp->file.index, p))
 658                         break;
 659                 err = 0;
 660                 break;
 661
 662         case PPPIOCSDEBUG:
 663                 if (get_user(val, p))
 664                         break;
 665                 ppp->debug = val;
 666                 err = 0;
 667                 break;
 668
 669         case PPPIOCGDEBUG:
 670                 if (put_user(ppp->debug, p))
 671                         break;
 672                 err = 0;
 673                 break;
 674
 675         case PPPIOCGIDLE:
 676                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 677                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
 678                 if (copy_to_user(argp, &idle, sizeof(idle)))
 679                         break;
 680                 err = 0;
 681                 break;
 682
 683         case PPPIOCSMAXCID:
 684                 if (get_user(val, p))
 685                         break;
 686                 val2 = 15;
 687                 if ((val >> 16) != 0) {
 688                         val2 = val >> 16;
 689                         val &= 0xffff;
 690                 }
 691                 vj = slhc_init(val2+1, val+1);
 692                 if (vj == 0) {
 693                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
 694                         err = -ENOMEM;
 695                         break;
 696                 }
 697                 ppp_lock(ppp);
 698                 if (ppp->vj != 0)
 699                         slhc_free(ppp->vj);
 700                 ppp->vj = vj;
 701                 ppp_unlock(ppp);
 702                 err = 0;
 703                 break;
 704
 705         case PPPIOCGNPMODE:
 706         case PPPIOCSNPMODE:
 707                 if (copy_from_user(&npi, argp, sizeof(npi)))
 708                         break;
 709                 err = proto_to_npindex(npi.protocol);
 710                 if (err < 0)
 711                         break;
 712                 i = err;
 713                 if (cmd == PPPIOCGNPMODE) {
 714                         err = -EFAULT;
 715                         npi.mode = ppp->npmode[i];
 716                         if (copy_to_user(argp, &npi, sizeof(npi)))
 717                                 break;
 718                 } else {
 719                         ppp->npmode[i] = npi.mode;
 720                         /* we may be able to transmit more packets now (??) */
 721                         netif_wake_queue(ppp->dev);
 722                 }
 723                 err = 0;
 724                 break;
 725
 726 #ifdef CONFIG_PPP_FILTER
 727         case PPPIOCSPASS:
 728         {
 729                 struct sock_filter *code;
 730                 err = get_filter(argp, &code);
 731                 if (err >= 0) {
 732                         ppp_lock(ppp);
 733                         kfree(ppp->pass_filter);
 734                         ppp->pass_filter = code;
 735                         ppp->pass_len = err;
 736                         ppp_unlock(ppp);
 737                         err = 0;
 738                 }
 739                 break;
 740         }
 741         case PPPIOCSACTIVE:
 742         {
 743                 struct sock_filter *code;
 744                 err = get_filter(argp, &code);
 745                 if (err >= 0) {
 746                         ppp_lock(ppp);
 747                         kfree(ppp->active_filter);
 748                         ppp->active_filter = code;
 749                         ppp->active_len = err;
 750                         ppp_unlock(ppp);
 751                         err = 0;
 752                 }
 753                 break;
 754         }
 755 #endif /* CONFIG_PPP_FILTER */
 756
 757 #ifdef CONFIG_PPP_MULTILINK
 758         case PPPIOCSMRRU:
 759                 if (get_user(val, p))
 760                         break;
 761                 ppp_recv_lock(ppp);
 762                 ppp->mrru = val;
 763                 ppp_recv_unlock(ppp);
 764                 err = 0;
 765                 break;
 766 #endif /* CONFIG_PPP_MULTILINK */
 767
 768         default:
 769                 err = -ENOTTY;
 770         }
 771
 772         return err;
 773 }
 774
 775 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 776                                 unsigned int cmd, unsigned long arg)
 777 {
 778         int unit, err = -EFAULT;
 779         struct ppp *ppp;
 780         struct channel *chan;
 781         int __user *p = (int __user *)arg;
 782
 783         switch (cmd) {
 784         case PPPIOCNEWUNIT:
 785                 /* Create a new ppp unit */
 786                 if (get_user(unit, p))
 787                         break;
 788                 ppp = ppp_create_interface(unit, &err);
 789                 if (ppp == 0)
 790                         break;
 791                 file->private_data = &ppp->file;
 792                 ppp->owner = file;
 793                 err = -EFAULT;
 794                 if (put_user(ppp->file.index, p))
 795                         break;
 796                 err = 0;
 797                 break;
 798
 799         case PPPIOCATTACH:
 800                 /* Attach to an existing ppp unit */
 801                 if (get_user(unit, p))
 802                         break;
 803                 mutex_lock(&all_ppp_mutex);
 804                 err = -ENXIO;
 805                 ppp = ppp_find_unit(unit);
 806                 if (ppp != 0) {
 807                         atomic_inc(&ppp->file.refcnt);
 808                         file->private_data = &ppp->file;
 809                         err = 0;
 810                 }
 811                 mutex_unlock(&all_ppp_mutex);
 812                 break;
 813
 814         case PPPIOCATTCHAN:
 815                 if (get_user(unit, p))
 816                         break;
 817                 spin_lock_bh(&all_channels_lock);
 818                 err = -ENXIO;
 819                 chan = ppp_find_channel(unit);
 820                 if (chan != 0) {
 821                         atomic_inc(&chan->file.refcnt);
 822                         file->private_data = &chan->file;
 823                         err = 0;
 824                 }
 825                 spin_unlock_bh(&all_channels_lock);
 826                 break;
 827
 828         default:
 829                 err = -ENOTTY;
 830         }
 831         return err;
 832 }
 833
 834 static const struct file_operations ppp_device_fops = {
 835         .owner          = THIS_MODULE,
 836         .read           = ppp_read,
 837         .write          = ppp_write,
 838         .poll           = ppp_poll,
 839         .ioctl          = ppp_ioctl,
 840         .open           = ppp_open,
 841         .release        = ppp_release
 842 };
 843
 844 #define PPP_MAJOR       108
 845
 846 /* Called at boot time if ppp is compiled into the kernel,
 847    or at module load time (from init_module) if compiled as a module. */
 848 static int __init ppp_init(void)
 849 {
 850         int err;
 851
 852         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
 853         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
 854         if (!err) {
 855                 ppp_class = class_create(THIS_MODULE, "ppp");
 856                 if (IS_ERR(ppp_class)) {
 857                         err = PTR_ERR(ppp_class);
 858                         goto out_chrdev;
 859                 }
 860                 device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), "ppp");
 861         }
 862
 863 out:
 864         if (err)
 865                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
 866         return err;
 867
 868 out_chrdev:
 869         unregister_chrdev(PPP_MAJOR, "ppp");
 870         goto out;
 871 }
 872
 873 /*
 874  * Network interface unit routines.
 875  */
 876 static int
 877 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 878 {
 879         struct ppp *ppp = (struct ppp *) dev->priv;
 880         int npi, proto;
 881         unsigned char *pp;
 882
 883         npi = ethertype_to_npindex(ntohs(skb->protocol));
 884         if (npi < 0)
 885                 goto outf;
 886
 887         /* Drop, accept or reject the packet */
 888         switch (ppp->npmode[npi]) {
 889         case NPMODE_PASS:
 890                 break;
 891         case NPMODE_QUEUE:
 892                 /* it would be nice to have a way to tell the network
 893                    system to queue this one up for later. */
 894                 goto outf;
 895         case NPMODE_DROP:
 896         case NPMODE_ERROR:
 897                 goto outf;
 898         }
 899
 900         /* Put the 2-byte PPP protocol number on the front,
 901            making sure there is room for the address and control fields. */
 902         if (skb_headroom(skb) < PPP_HDRLEN) {
 903                 struct sk_buff *ns;
 904
 905                 ns = alloc_skb(skb->len + dev->hard_header_len, GFP_ATOMIC);
 906                 if (ns == 0)
 907                         goto outf;
 908                 skb_reserve(ns, dev->hard_header_len);
 909                 skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
 910                 kfree_skb(skb);
 911                 skb = ns;
 912         }
 913         pp = skb_push(skb, 2);
 914         proto = npindex_to_proto[npi];
 915         pp[0] = proto >> 8;
 916         pp[1] = proto;
 917
 918         netif_stop_queue(dev);
 919         skb_queue_tail(&ppp->file.xq, skb);
 920         ppp_xmit_process(ppp);
 921         return 0;
 922
 923  outf:
 924         kfree_skb(skb);
 925         ++ppp->stats.tx_dropped;
 926         return 0;
 927 }
 928
 929 static struct net_device_stats *
 930 ppp_net_stats(struct net_device *dev)
 931 {
 932         struct ppp *ppp = (struct ppp *) dev->priv;
 933
 934         return &ppp->stats;
 935 }
 936
 937 static int
 938 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 939 {
 940         struct ppp *ppp = dev->priv;
 941         int err = -EFAULT;
 942         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
 943         struct ppp_stats stats;
 944         struct ppp_comp_stats cstats;
 945         char *vers;
 946
 947         switch (cmd) {
 948         case SIOCGPPPSTATS:
 949                 ppp_get_stats(ppp, &stats);
 950                 if (copy_to_user(addr, &stats, sizeof(stats)))
 951                         break;
 952                 err = 0;
 953                 break;
 954
 955         case SIOCGPPPCSTATS:
 956                 memset(&cstats, 0, sizeof(cstats));
 957                 if (ppp->xc_state != 0)
 958                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
 959                 if (ppp->rc_state != 0)
 960                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
 961                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
 962                         break;
 963                 err = 0;
 964                 break;
 965
 966         case SIOCGPPPVER:
 967                 vers = PPP_VERSION;
 968                 if (copy_to_user(addr, vers, strlen(vers) + 1))
 969                         break;
 970                 err = 0;
 971                 break;
 972
 973         default:
 974                 err = -EINVAL;
 975         }
 976
 977         return err;
 978 }
 979
 980 static void ppp_setup(struct net_device *dev)
 981 {
 982         dev->hard_header_len = PPP_HDRLEN;
 983         dev->mtu = PPP_MTU;
 984         dev->addr_len = 0;
 985         dev->tx_queue_len = 3;
 986         dev->type = ARPHRD_PPP;
 987         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
 988 }
 989
 990 /*
 991  * Transmit-side routines.
 992  */
 993
 994 /*
 995  * Called to do any work queued up on the transmit side
 996  * that can now be done.
 997  */
 998 static void
 999 ppp_xmit_process(struct ppp *ppp)
1000 {
1001         struct sk_buff *skb;
1002
1003         ppp_xmit_lock(ppp);
1004         if (ppp->dev != 0) {
1005                 ppp_push(ppp);
1006                 while (ppp->xmit_pending == 0
1007                        && (skb = skb_dequeue(&ppp->file.xq)) != 0)
1008                         ppp_send_frame(ppp, skb);
1009                 /* If there's no work left to do, tell the core net
1010                    code that we can accept some more. */
1011                 if (ppp->xmit_pending == 0 && skb_peek(&ppp->file.xq) == 0)
1012                         netif_wake_queue(ppp->dev);
1013         }
1014         ppp_xmit_unlock(ppp);
1015 }
1016
1017 static inline struct sk_buff *
1018 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1019 {
1020         struct sk_buff *new_skb;
1021         int len;
1022         int new_skb_size = ppp->dev->mtu +
1023                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1024         int compressor_skb_size = ppp->dev->mtu +
1025                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1026         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1027         if (!new_skb) {
1028                 if (net_ratelimit())
1029                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1030                 return NULL;
1031         }
1032         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1033                 skb_reserve(new_skb,
1034                             ppp->dev->hard_header_len - PPP_HDRLEN);
1035
1036         /* compressor still expects A/C bytes in hdr */
1037         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1038                                    new_skb->data, skb->len + 2,
1039                                    compressor_skb_size);
1040         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1041                 kfree_skb(skb);
1042                 skb = new_skb;
1043                 skb_put(skb, len);
1044                 skb_pull(skb, 2);       /* pull off A/C bytes */
1045         } else if (len == 0) {
1046                 /* didn't compress, or CCP not up yet */
1047                 kfree_skb(new_skb);
1048                 new_skb = skb;
1049         } else {
1050                 /*
1051                  * (len < 0)
1052                  * MPPE requires that we do not send unencrypted
1053                  * frames.  The compressor will return -1 if we
1054                  * should drop the frame.  We cannot simply test
1055                  * the compress_proto because MPPE and MPPC share
1056                  * the same number.
1057                  */
1058                 if (net_ratelimit())
1059                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1060                 kfree_skb(skb);
1061                 kfree_skb(new_skb);
1062                 new_skb = NULL;
1063         }
1064         return new_skb;
1065 }
1066
1067 /*
1068  * Compress and send a frame.
1069  * The caller should have locked the xmit path,
1070  * and xmit_pending should be 0.
1071  */
1072 static void
1073 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1074 {
1075         int proto = PPP_PROTO(skb);
1076         struct sk_buff *new_skb;
1077         int len;
1078         unsigned char *cp;
1079
1080         if (proto < 0x8000) {
1081 #ifdef CONFIG_PPP_FILTER
1082                 /* check if we should pass this packet */
1083                 /* the filter instructions are constructed assuming
1084                    a four-byte PPP header on each packet */
1085                 *skb_push(skb, 2) = 1;
1086                 if (ppp->pass_filter
1087                     && sk_run_filter(skb, ppp->pass_filter,
1088                                      ppp->pass_len) == 0) {
1089                         if (ppp->debug & 1)
1090                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1091                         kfree_skb(skb);
1092                         return;
1093                 }
1094                 /* if this packet passes the active filter, record the time */
1095                 if (!(ppp->active_filter
1096                       && sk_run_filter(skb, ppp->active_filter,
1097                                        ppp->active_len) == 0))
1098                         ppp->last_xmit = jiffies;
1099                 skb_pull(skb, 2);
1100 #else
1101                 /* for data packets, record the time */
1102                 ppp->last_xmit = jiffies;
1103 #endif /* CONFIG_PPP_FILTER */
1104         }
1105
1106         ++ppp->stats.tx_packets;
1107         ppp->stats.tx_bytes += skb->len - 2;
1108
1109         switch (proto) {
1110         case PPP_IP:
1111                 if (ppp->vj == 0 || (ppp->flags & SC_COMP_TCP) == 0)
1112                         break;
1113                 /* try to do VJ TCP header compression */
1114                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1115                                     GFP_ATOMIC);
1116                 if (new_skb == 0) {
1117                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1118                         goto drop;
1119                 }
1120                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1121                 cp = skb->data + 2;
1122                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1123                                     new_skb->data + 2, &cp,
1124                                     !(ppp->flags & SC_NO_TCP_CCID));
1125                 if (cp == skb->data + 2) {
1126                         /* didn't compress */
1127                         kfree_skb(new_skb);
1128                 } else {
1129                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1130                                 proto = PPP_VJC_COMP;
1131                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1132                         } else {
1133                                 proto = PPP_VJC_UNCOMP;
1134                                 cp[0] = skb->data[2];
1135                         }
1136                         kfree_skb(skb);
1137                         skb = new_skb;
1138                         cp = skb_put(skb, len + 2);
1139                         cp[0] = 0;
1140                         cp[1] = proto;
1141                 }
1142                 break;
1143
1144         case PPP_CCP:
1145                 /* peek at outbound CCP frames */
1146                 ppp_ccp_peek(ppp, skb, 0);
1147                 break;
1148         }
1149
1150         /* try to do packet compression */
1151         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0
1152             && proto != PPP_LCP && proto != PPP_CCP) {
1153                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1154                         if (net_ratelimit())
1155                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1156                         goto drop;
1157                 }
1158                 skb = pad_compress_skb(ppp, skb);
1159                 if (!skb)
1160                         goto drop;
1161         }
1162
1163         /*
1164          * If we are waiting for traffic (demand dialling),
1165          * queue it up for pppd to receive.
1166          */
1167         if (ppp->flags & SC_LOOP_TRAFFIC) {
1168                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1169                         goto drop;
1170                 skb_queue_tail(&ppp->file.rq, skb);
1171                 wake_up_interruptible(&ppp->file.rwait);
1172                 return;
1173         }
1174
1175         ppp->xmit_pending = skb;
1176         ppp_push(ppp);
1177         return;
1178
1179  drop:
1180         if (skb)
1181                 kfree_skb(skb);
1182         ++ppp->stats.tx_errors;
1183 }
1184
1185 /*
1186  * Try to send the frame in xmit_pending.
1187  * The caller should have the xmit path locked.
1188  */
1189 static void
1190 ppp_push(struct ppp *ppp)
1191 {
1192         struct list_head *list;
1193         struct channel *pch;
1194         struct sk_buff *skb = ppp->xmit_pending;
1195
1196         if (skb == 0)
1197                 return;
1198
1199         list = &ppp->channels;
1200         if (list_empty(list)) {
1201                 /* nowhere to send the packet, just drop it */
1202                 ppp->xmit_pending = NULL;
1203                 kfree_skb(skb);
1204                 return;
1205         }
1206
1207         if ((ppp->flags & SC_MULTILINK) == 0) {
1208                 /* not doing multilink: send it down the first channel */
1209                 list = list->next;
1210                 pch = list_entry(list, struct channel, clist);
1211
1212                 spin_lock_bh(&pch->downl);
1213                 if (pch->chan) {
1214                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1215                                 ppp->xmit_pending = NULL;
1216                 } else {
1217                         /* channel got unregistered */
1218                         kfree_skb(skb);
1219                         ppp->xmit_pending = NULL;
1220                 }
1221                 spin_unlock_bh(&pch->downl);
1222                 return;
1223         }
1224
1225 #ifdef CONFIG_PPP_MULTILINK
1226         /* Multilink: fragment the packet over as many links
1227            as can take the packet at the moment. */
1228         if (!ppp_mp_explode(ppp, skb))
1229                 return;
1230 #endif /* CONFIG_PPP_MULTILINK */
1231
1232         ppp->xmit_pending = NULL;
1233         kfree_skb(skb);
1234 }
1235
1236 #ifdef CONFIG_PPP_MULTILINK
1237 /*
1238  * Divide a packet to be transmitted into fragments and
1239  * send them out the individual links.
1240  */
1241 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1242 {
1243         int len, fragsize;
1244         int i, bits, hdrlen, mtu;
1245         int flen;
1246         int navail, nfree;
1247         int nbigger;
1248         unsigned char *p, *q;
1249         struct list_head *list;
1250         struct channel *pch;
1251         struct sk_buff *frag;
1252         struct ppp_channel *chan;
1253
1254         nfree = 0;      /* # channels which have no packet already queued */
1255         navail = 0;     /* total # of usable channels (not deregistered) */
1256         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1257         i = 0;
1258         list_for_each_entry(pch, &ppp->channels, clist) {
1259                 navail += pch->avail = (pch->chan != NULL);
1260                 if (pch->avail) {
1261                         if (skb_queue_empty(&pch->file.xq) ||
1262                             !pch->had_frag) {
1263                                 pch->avail = 2;
1264                                 ++nfree;
1265                         }
1266                         if (!pch->had_frag && i < ppp->nxchan)
1267                                 ppp->nxchan = i;
1268                 }
1269                 ++i;
1270         }
1271
1272         /*
1273          * Don't start sending this packet unless at least half of
1274          * the channels are free.  This gives much better TCP
1275          * performance if we have a lot of channels.
1276          */
1277         if (nfree == 0 || nfree < navail / 2)
1278                 return 0;       /* can't take now, leave it in xmit_pending */
1279
1280         /* Do protocol field compression (XXX this should be optional) */
1281         p = skb->data;
1282         len = skb->len;
1283         if (*p == 0) {
1284                 ++p;
1285                 --len;
1286         }
1287
1288         /*
1289          * Decide on fragment size.
1290          * We create a fragment for each free channel regardless of
1291          * how small they are (i.e. even 0 length) in order to minimize
1292          * the time that it will take to detect when a channel drops
1293          * a fragment.
1294          */
1295         fragsize = len;
1296         if (nfree > 1)
1297                 fragsize = DIV_ROUND_UP(fragsize, nfree);
1298         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1299            except if nbigger==0, then they all get fragsize. */
1300         nbigger = len % nfree;
1301
1302         /* skip to the channel after the one we last used
1303            and start at that one */
1304         list = &ppp->channels;
1305         for (i = 0; i < ppp->nxchan; ++i) {
1306                 list = list->next;
1307                 if (list == &ppp->channels) {
1308                         i = 0;
1309                         break;
1310                 }
1311         }
1312
1313         /* create a fragment for each channel */
1314         bits = B;
1315         while (nfree > 0 || len > 0) {
1316                 list = list->next;
1317                 if (list == &ppp->channels) {
1318                         i = 0;
1319                         continue;
1320                 }
1321                 pch = list_entry(list, struct channel, clist);
1322                 ++i;
1323                 if (!pch->avail)
1324                         continue;
1325
1326                 /*
1327                  * Skip this channel if it has a fragment pending already and
1328                  * we haven't given a fragment to all of the free channels.
1329                  */
1330                 if (pch->avail == 1) {
1331                         if (nfree > 0)
1332                                 continue;
1333                 } else {
1334                         --nfree;
1335                         pch->avail = 1;
1336                 }
1337
1338                 /* check the channel's mtu and whether it is still attached. */
1339                 spin_lock_bh(&pch->downl);
1340                 if (pch->chan == NULL) {
1341                         /* can't use this channel, it's being deregistered */
1342                         spin_unlock_bh(&pch->downl);
1343                         pch->avail = 0;
1344                         if (--navail == 0)
1345                                 break;
1346                         continue;
1347                 }
1348
1349                 /*
1350                  * Create a fragment for this channel of
1351                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1352                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1353                  * MTU, so we use mtu = 2 + hdrlen.
1354                  */
1355                 if (fragsize > len)
1356                         fragsize = len;
1357                 flen = fragsize;
1358                 mtu = pch->chan->mtu + 2 - hdrlen;
1359                 if (mtu < 4)
1360                         mtu = 4;
1361                 if (flen > mtu)
1362                         flen = mtu;
1363                 if (flen == len && nfree == 0)
1364                         bits |= E;
1365                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1366                 if (frag == 0)
1367                         goto noskb;
1368                 q = skb_put(frag, flen + hdrlen);
1369
1370                 /* make the MP header */
1371                 q[0] = PPP_MP >> 8;
1372                 q[1] = PPP_MP;
1373                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1374                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1375                         q[3] = ppp->nxseq;
1376                 } else {
1377                         q[2] = bits;
1378                         q[3] = ppp->nxseq >> 16;
1379                         q[4] = ppp->nxseq >> 8;
1380                         q[5] = ppp->nxseq;
1381                 }
1382
1383                 /*
1384                  * Copy the data in.
1385                  * Unfortunately there is a bug in older versions of
1386                  * the Linux PPP multilink reconstruction code where it
1387                  * drops 0-length fragments.  Therefore we make sure the
1388                  * fragment has at least one byte of data.  Any bytes
1389                  * we add in this situation will end up as padding on the
1390                  * end of the reconstructed packet.
1391                  */
1392                 if (flen == 0)
1393                         *skb_put(frag, 1) = 0;
1394                 else
1395                         memcpy(q + hdrlen, p, flen);
1396
1397                 /* try to send it down the channel */
1398                 chan = pch->chan;
1399                 if (!skb_queue_empty(&pch->file.xq) ||
1400                     !chan->ops->start_xmit(chan, frag))
1401                         skb_queue_tail(&pch->file.xq, frag);
1402                 pch->had_frag = 1;
1403                 p += flen;
1404                 len -= flen;
1405                 ++ppp->nxseq;
1406                 bits = 0;
1407                 spin_unlock_bh(&pch->downl);
1408
1409                 if (--nbigger == 0 && fragsize > 0)
1410                         --fragsize;
1411         }
1412         ppp->nxchan = i;
1413
1414         return 1;
1415
1416  noskb:
1417         spin_unlock_bh(&pch->downl);
1418         if (ppp->debug & 1)
1419                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1420         ++ppp->stats.tx_errors;
1421         ++ppp->nxseq;
1422         return 1;       /* abandon the frame */
1423 }
1424 #endif /* CONFIG_PPP_MULTILINK */
1425
1426 /*
1427  * Try to send data out on a channel.
1428  */
1429 static void
1430 ppp_channel_push(struct channel *pch)
1431 {
1432         struct sk_buff *skb;
1433         struct ppp *ppp;
1434
1435         spin_lock_bh(&pch->downl);
1436         if (pch->chan != 0) {
1437                 while (!skb_queue_empty(&pch->file.xq)) {
1438                         skb = skb_dequeue(&pch->file.xq);
1439                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1440                                 /* put the packet back and try again later */
1441                                 skb_queue_head(&pch->file.xq, skb);
1442                                 break;
1443                         }
1444                 }
1445         } else {
1446                 /* channel got deregistered */
1447                 skb_queue_purge(&pch->file.xq);
1448         }
1449         spin_unlock_bh(&pch->downl);
1450         /* see if there is anything from the attached unit to be sent */
1451         if (skb_queue_empty(&pch->file.xq)) {
1452                 read_lock_bh(&pch->upl);
1453                 ppp = pch->ppp;
1454                 if (ppp != 0)
1455                         ppp_xmit_process(ppp);
1456                 read_unlock_bh(&pch->upl);
1457         }
1458 }
1459
1460 /*
1461  * Receive-side routines.
1462  */
1463
1464 /* misuse a few fields of the skb for MP reconstruction */
1465 #define sequence        priority
1466 #define BEbits          cb[0]
1467
1468 static inline void
1469 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1470 {
1471         ppp_recv_lock(ppp);
1472         /* ppp->dev == 0 means interface is closing down */
1473         if (ppp->dev != 0)
1474                 ppp_receive_frame(ppp, skb, pch);
1475         else
1476                 kfree_skb(skb);
1477         ppp_recv_unlock(ppp);
1478 }
1479
1480 void
1481 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1482 {
1483         struct channel *pch = chan->ppp;
1484         int proto;
1485
1486         if (pch == 0 || skb->len == 0) {
1487                 kfree_skb(skb);
1488                 return;
1489         }
1490
1491         proto = PPP_PROTO(skb);
1492         read_lock_bh(&pch->upl);
1493         if (pch->ppp == 0 || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1494                 /* put it on the channel queue */
1495                 skb_queue_tail(&pch->file.rq, skb);
1496                 /* drop old frames if queue too long */
1497                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1498                        && (skb = skb_dequeue(&pch->file.rq)) != 0)
1499                         kfree_skb(skb);
1500                 wake_up_interruptible(&pch->file.rwait);
1501         } else {
1502                 ppp_do_recv(pch->ppp, skb, pch);
1503         }
1504         read_unlock_bh(&pch->upl);
1505 }
1506
1507 /* Put a 0-length skb in the receive queue as an error indication */
1508 void
1509 ppp_input_error(struct ppp_channel *chan, int code)
1510 {
1511         struct channel *pch = chan->ppp;
1512         struct sk_buff *skb;
1513
1514         if (pch == 0)
1515                 return;
1516
1517         read_lock_bh(&pch->upl);
1518         if (pch->ppp != 0) {
1519                 skb = alloc_skb(0, GFP_ATOMIC);
1520                 if (skb != 0) {
1521                         skb->len = 0;           /* probably unnecessary */
1522                         skb->cb[0] = code;
1523                         ppp_do_recv(pch->ppp, skb, pch);
1524                 }
1525         }
1526         read_unlock_bh(&pch->upl);
1527 }
1528
1529 /*
1530  * We come in here to process a received frame.
1531  * The receive side of the ppp unit is locked.
1532  */
1533 static void
1534 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1535 {
1536         if (skb->len >= 2) {
1537 #ifdef CONFIG_PPP_MULTILINK
1538                 /* XXX do channel-level decompression here */
1539                 if (PPP_PROTO(skb) == PPP_MP)
1540                         ppp_receive_mp_frame(ppp, skb, pch);
1541                 else
1542 #endif /* CONFIG_PPP_MULTILINK */
1543                         ppp_receive_nonmp_frame(ppp, skb);
1544                 return;
1545         }
1546
1547         if (skb->len > 0)
1548                 /* note: a 0-length skb is used as an error indication */
1549                 ++ppp->stats.rx_length_errors;
1550
1551         kfree_skb(skb);
1552         ppp_receive_error(ppp);
1553 }
1554
1555 static void
1556 ppp_receive_error(struct ppp *ppp)
1557 {
1558         ++ppp->stats.rx_errors;
1559         if (ppp->vj != 0)
1560                 slhc_toss(ppp->vj);
1561 }
1562
1563 static void
1564 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1565 {
1566         struct sk_buff *ns;
1567         int proto, len, npi;
1568
1569         /*
1570          * Decompress the frame, if compressed.
1571          * Note that some decompressors need to see uncompressed frames
1572          * that come in as well as compressed frames.
1573          */
1574         if (ppp->rc_state != 0 && (ppp->rstate & SC_DECOMP_RUN)
1575             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1576                 skb = ppp_decompress_frame(ppp, skb);
1577
1578         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1579                 goto err;
1580
1581         proto = PPP_PROTO(skb);
1582         switch (proto) {
1583         case PPP_VJC_COMP:
1584                 /* decompress VJ compressed packets */
1585                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1586                         goto err;
1587
1588                 if (skb_tailroom(skb) < 124) {
1589                         /* copy to a new sk_buff with more tailroom */
1590                         ns = dev_alloc_skb(skb->len + 128);
1591                         if (ns == 0) {
1592                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1593                                 goto err;
1594                         }
1595                         skb_reserve(ns, 2);
1596                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1597                         kfree_skb(skb);
1598                         skb = ns;
1599                 }
1600                 else
1601                         skb->ip_summed = CHECKSUM_NONE;
1602
1603                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1604                 if (len <= 0) {
1605                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1606                         goto err;
1607                 }
1608                 len += 2;
1609                 if (len > skb->len)
1610                         skb_put(skb, len - skb->len);
1611                 else if (len < skb->len)
1612                         skb_trim(skb, len);
1613                 proto = PPP_IP;
1614                 break;
1615
1616         case PPP_VJC_UNCOMP:
1617                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1618                         goto err;
1619
1620                 /* Until we fix the decompressor need to make sure
1621                  * data portion is linear.
1622                  */
1623                 if (!pskb_may_pull(skb, skb->len))
1624                         goto err;
1625
1626                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1627                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1628                         goto err;
1629                 }
1630                 proto = PPP_IP;
1631                 break;
1632
1633         case PPP_CCP:
1634                 ppp_ccp_peek(ppp, skb, 1);
1635                 break;
1636         }
1637
1638         ++ppp->stats.rx_packets;
1639         ppp->stats.rx_bytes += skb->len - 2;
1640
1641         npi = proto_to_npindex(proto);
1642         if (npi < 0) {
1643                 /* control or unknown frame - pass it to pppd */
1644                 skb_queue_tail(&ppp->file.rq, skb);
1645                 /* limit queue length by dropping old frames */
1646                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1647                        && (skb = skb_dequeue(&ppp->file.rq)) != 0)
1648                         kfree_skb(skb);
1649                 /* wake up any process polling or blocking on read */
1650                 wake_up_interruptible(&ppp->file.rwait);
1651
1652         } else {
1653                 /* network protocol frame - give it to the kernel */
1654
1655 #ifdef CONFIG_PPP_FILTER
1656                 /* check if the packet passes the pass and active filters */
1657                 /* the filter instructions are constructed assuming
1658                    a four-byte PPP header on each packet */
1659                 *skb_push(skb, 2) = 0;
1660                 if (ppp->pass_filter
1661                     && sk_run_filter(skb, ppp->pass_filter,
1662                                      ppp->pass_len) == 0) {
1663                         if (ppp->debug & 1)
1664                                 printk(KERN_DEBUG "PPP: inbound frame not passed\n");
1665                         kfree_skb(skb);
1666                         return;
1667                 }
1668                 if (!(ppp->active_filter
1669                       && sk_run_filter(skb, ppp->active_filter,
1670                                        ppp->active_len) == 0))
1671                         ppp->last_recv = jiffies;
1672                 skb_pull(skb, 2);
1673 #else
1674                 ppp->last_recv = jiffies;
1675 #endif /* CONFIG_PPP_FILTER */
1676
1677                 if ((ppp->dev->flags & IFF_UP) == 0
1678                     || ppp->npmode[npi] != NPMODE_PASS) {
1679                         kfree_skb(skb);
1680                 } else {
1681                         /* chop off protocol */
1682                         skb_pull_rcsum(skb, 2);
1683                         skb->dev = ppp->dev;
1684                         skb->protocol = htons(npindex_to_ethertype[npi]);
1685                         skb_reset_mac_header(skb);
1686                         netif_rx(skb);
1687                         ppp->dev->last_rx = jiffies;
1688                 }
1689         }
1690         return;
1691
1692  err:
1693         kfree_skb(skb);
1694         ppp_receive_error(ppp);
1695 }
1696
1697 static struct sk_buff *
1698 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1699 {
1700         int proto = PPP_PROTO(skb);
1701         struct sk_buff *ns;
1702         int len;
1703
1704         /* Until we fix all the decompressor's need to make sure
1705          * data portion is linear.
1706          */
1707         if (!pskb_may_pull(skb, skb->len))
1708                 goto err;
1709
1710         if (proto == PPP_COMP) {
1711                 int obuff_size;
1712
1713                 switch(ppp->rcomp->compress_proto) {
1714                 case CI_MPPE:
1715                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1716                         break;
1717                 default:
1718                         obuff_size = ppp->mru + PPP_HDRLEN;
1719                         break;
1720                 }
1721
1722                 ns = dev_alloc_skb(obuff_size);
1723                 if (ns == 0) {
1724                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1725                         goto err;
1726                 }
1727                 /* the decompressor still expects the A/C bytes in the hdr */
1728                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1729                                 skb->len + 2, ns->data, obuff_size);
1730                 if (len < 0) {
1731                         /* Pass the compressed frame to pppd as an
1732                            error indication. */
1733                         if (len == DECOMP_FATALERROR)
1734                                 ppp->rstate |= SC_DC_FERROR;
1735                         kfree_skb(ns);
1736                         goto err;
1737                 }
1738
1739                 kfree_skb(skb);
1740                 skb = ns;
1741                 skb_put(skb, len);
1742                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1743
1744         } else {
1745                 /* Uncompressed frame - pass to decompressor so it
1746                    can update its dictionary if necessary. */
1747                 if (ppp->rcomp->incomp)
1748                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1749                                            skb->len + 2);
1750         }
1751
1752         return skb;
1753
1754  err:
1755         ppp->rstate |= SC_DC_ERROR;
1756         ppp_receive_error(ppp);
1757         return skb;
1758 }
1759
1760 #ifdef CONFIG_PPP_MULTILINK
1761 /*
1762  * Receive a multilink frame.
1763  * We put it on the reconstruction queue and then pull off
1764  * as many completed frames as we can.
1765  */
1766 static void
1767 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1768 {
1769         u32 mask, seq;
1770         struct channel *ch;
1771         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1772
1773         if (!pskb_may_pull(skb, mphdrlen) || ppp->mrru == 0)
1774                 goto err;               /* no good, throw it away */
1775
1776         /* Decode sequence number and begin/end bits */
1777         if (ppp->flags & SC_MP_SHORTSEQ) {
1778                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1779                 mask = 0xfff;
1780         } else {
1781                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1782                 mask = 0xffffff;
1783         }
1784         skb->BEbits = skb->data[2];
1785         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1786
1787         /*
1788          * Do protocol ID decompression on the first fragment of each packet.
1789          */
1790         if ((skb->BEbits & B) && (skb->data[0] & 1))
1791                 *skb_push(skb, 1) = 0;
1792
1793         /*
1794          * Expand sequence number to 32 bits, making it as close
1795          * as possible to ppp->minseq.
1796          */
1797         seq |= ppp->minseq & ~mask;
1798         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1799                 seq += mask + 1;
1800         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1801                 seq -= mask + 1;        /* should never happen */
1802         skb->sequence = seq;
1803         pch->lastseq = seq;
1804
1805         /*
1806          * If this packet comes before the next one we were expecting,
1807          * drop it.
1808          */
1809         if (seq_before(seq, ppp->nextseq)) {
1810                 kfree_skb(skb);
1811                 ++ppp->stats.rx_dropped;
1812                 ppp_receive_error(ppp);
1813                 return;
1814         }
1815
1816         /*
1817          * Reevaluate minseq, the minimum over all channels of the
1818          * last sequence number received on each channel.  Because of
1819          * the increasing sequence number rule, we know that any fragment
1820          * before `minseq' which hasn't arrived is never going to arrive.
1821          * The list of channels can't change because we have the receive
1822          * side of the ppp unit locked.
1823          */
1824         list_for_each_entry(ch, &ppp->channels, clist) {
1825                 if (seq_before(ch->lastseq, seq))
1826                         seq = ch->lastseq;
1827         }
1828         if (seq_before(ppp->minseq, seq))
1829                 ppp->minseq = seq;
1830
1831         /* Put the fragment on the reconstruction queue */
1832         ppp_mp_insert(ppp, skb);
1833
1834         /* If the queue is getting long, don't wait any longer for packets
1835            before the start of the queue. */
1836         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN
1837             && seq_before(ppp->minseq, ppp->mrq.next->sequence))
1838                 ppp->minseq = ppp->mrq.next->sequence;
1839
1840         /* Pull completed packets off the queue and receive them. */
1841         while ((skb = ppp_mp_reconstruct(ppp)) != 0)
1842                 ppp_receive_nonmp_frame(ppp, skb);
1843
1844         return;
1845
1846  err:
1847         kfree_skb(skb);
1848         ppp_receive_error(ppp);
1849 }
1850
1851 /*
1852  * Insert a fragment on the MP reconstruction queue.
1853  * The queue is ordered by increasing sequence number.
1854  */
1855 static void
1856 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1857 {
1858         struct sk_buff *p;
1859         struct sk_buff_head *list = &ppp->mrq;
1860         u32 seq = skb->sequence;
1861
1862         /* N.B. we don't need to lock the list lock because we have the
1863            ppp unit receive-side lock. */
1864         for (p = list->next; p != (struct sk_buff *)list; p = p->next)
1865                 if (seq_before(seq, p->sequence))
1866                         break;
1867         __skb_insert(skb, p->prev, p, list);
1868 }
1869
1870 /*
1871  * Reconstruct a packet from the MP fragment queue.
1872  * We go through increasing sequence numbers until we find a
1873  * complete packet, or we get to the sequence number for a fragment
1874  * which hasn't arrived but might still do so.
1875  */
1876 struct sk_buff *
1877 ppp_mp_reconstruct(struct ppp *ppp)
1878 {
1879         u32 seq = ppp->nextseq;
1880         u32 minseq = ppp->minseq;
1881         struct sk_buff_head *list = &ppp->mrq;
1882         struct sk_buff *p, *next;
1883         struct sk_buff *head, *tail;
1884         struct sk_buff *skb = NULL;
1885         int lost = 0, len = 0;
1886
1887         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1888                 return NULL;
1889         head = list->next;
1890         tail = NULL;
1891         for (p = head; p != (struct sk_buff *) list; p = next) {
1892                 next = p->next;
1893                 if (seq_before(p->sequence, seq)) {
1894                         /* this can't happen, anyway ignore the skb */
1895                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1896                                p->sequence, seq);
1897                         head = next;
1898                         continue;
1899                 }
1900                 if (p->sequence != seq) {
1901                         /* Fragment `seq' is missing.  If it is after
1902                            minseq, it might arrive later, so stop here. */
1903                         if (seq_after(seq, minseq))
1904                                 break;
1905                         /* Fragment `seq' is lost, keep going. */
1906                         lost = 1;
1907                         seq = seq_before(minseq, p->sequence)?
1908                                 minseq + 1: p->sequence;
1909                         next = p;
1910                         continue;
1911                 }
1912
1913                 /*
1914                  * At this point we know that all the fragments from
1915                  * ppp->nextseq to seq are either present or lost.
1916                  * Also, there are no complete packets in the queue
1917                  * that have no missing fragments and end before this
1918                  * fragment.
1919                  */
1920
1921                 /* B bit set indicates this fragment starts a packet */
1922                 if (p->BEbits & B) {
1923                         head = p;
1924                         lost = 0;
1925                         len = 0;
1926                 }
1927
1928                 len += p->len;
1929
1930                 /* Got a complete packet yet? */
1931                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1932                         if (len > ppp->mrru + 2) {
1933                                 ++ppp->stats.rx_length_errors;
1934                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1935                                        " is too long (%d)\n", len);
1936                         } else if (p == head) {
1937                                 /* fragment is complete packet - reuse skb */
1938                                 tail = p;
1939                                 skb = skb_get(p);
1940                                 break;
1941                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1942                                 ++ppp->stats.rx_missed_errors;
1943                                 printk(KERN_DEBUG "PPP: no memory for "
1944                                        "reconstructed packet");
1945                         } else {
1946                                 tail = p;
1947                                 break;
1948                         }
1949                         ppp->nextseq = seq + 1;
1950                 }
1951
1952                 /*
1953                  * If this is the ending fragment of a packet,
1954                  * and we haven't found a complete valid packet yet,
1955                  * we can discard up to and including this fragment.
1956                  */
1957                 if (p->BEbits & E)
1958                         head = next;
1959
1960                 ++seq;
1961         }
1962
1963         /* If we have a complete packet, copy it all into one skb. */
1964         if (tail != NULL) {
1965                 /* If we have discarded any fragments,
1966                    signal a receive error. */
1967                 if (head->sequence != ppp->nextseq) {
1968                         if (ppp->debug & 1)
1969                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1970                                        ppp->nextseq, head->sequence-1);
1971                         ++ppp->stats.rx_dropped;
1972                         ppp_receive_error(ppp);
1973                 }
1974
1975                 if (head != tail)
1976                         /* copy to a single skb */
1977                         for (p = head; p != tail->next; p = p->next)
1978                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1979                 ppp->nextseq = tail->sequence + 1;
1980                 head = tail->next;
1981         }
1982
1983         /* Discard all the skbuffs that we have copied the data out of
1984            or that we can't use. */
1985         while ((p = list->next) != head) {
1986                 __skb_unlink(p, list);
1987                 kfree_skb(p);
1988         }
1989
1990         return skb;
1991 }
1992 #endif /* CONFIG_PPP_MULTILINK */
1993
1994 /*
1995  * Channel interface.
1996  */
1997
1998 /*
1999  * Create a new, unattached ppp channel.
2000  */
2001 int
2002 ppp_register_channel(struct ppp_channel *chan)
2003 {
2004         struct channel *pch;
2005
2006         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2007         if (pch == 0)
2008                 return -ENOMEM;
2009         pch->ppp = NULL;
2010         pch->chan = chan;
2011         chan->ppp = pch;
2012         init_ppp_file(&pch->file, CHANNEL);
2013         pch->file.hdrlen = chan->hdrlen;
2014 #ifdef CONFIG_PPP_MULTILINK
2015         pch->lastseq = -1;
2016 #endif /* CONFIG_PPP_MULTILINK */
2017         init_rwsem(&pch->chan_sem);
2018         spin_lock_init(&pch->downl);
2019         rwlock_init(&pch->upl);
2020         spin_lock_bh(&all_channels_lock);
2021         pch->file.index = ++last_channel_index;
2022         list_add(&pch->list, &new_channels);
2023         atomic_inc(&channel_count);
2024         spin_unlock_bh(&all_channels_lock);
2025         return 0;
2026 }
2027
2028 /*
2029  * Return the index of a channel.
2030  */
2031 int ppp_channel_index(struct ppp_channel *chan)
2032 {
2033         struct channel *pch = chan->ppp;
2034
2035         if (pch != 0)
2036                 return pch->file.index;
2037         return -1;
2038 }
2039
2040 /*
2041  * Return the PPP unit number to which a channel is connected.
2042  */
2043 int ppp_unit_number(struct ppp_channel *chan)
2044 {
2045         struct channel *pch = chan->ppp;
2046         int unit = -1;
2047
2048         if (pch != 0) {
2049                 read_lock_bh(&pch->upl);
2050                 if (pch->ppp != 0)
2051                         unit = pch->ppp->file.index;
2052                 read_unlock_bh(&pch->upl);
2053         }
2054         return unit;
2055 }
2056
2057 /*
2058  * Disconnect a channel from the generic layer.
2059  * This must be called in process context.
2060  */
2061 void
2062 ppp_unregister_channel(struct ppp_channel *chan)
2063 {
2064         struct channel *pch = chan->ppp;
2065
2066         if (pch == 0)
2067                 return;         /* should never happen */
2068         chan->ppp = NULL;
2069
2070         /*
2071          * This ensures that we have returned from any calls into the
2072          * the channel's start_xmit or ioctl routine before we proceed.
2073          */
2074         down_write(&pch->chan_sem);
2075         spin_lock_bh(&pch->downl);
2076         pch->chan = NULL;
2077         spin_unlock_bh(&pch->downl);
2078         up_write(&pch->chan_sem);
2079         ppp_disconnect_channel(pch);
2080         spin_lock_bh(&all_channels_lock);
2081         list_del(&pch->list);
2082         spin_unlock_bh(&all_channels_lock);
2083         pch->file.dead = 1;
2084         wake_up_interruptible(&pch->file.rwait);
2085         if (atomic_dec_and_test(&pch->file.refcnt))
2086                 ppp_destroy_channel(pch);
2087 }
2088
2089 /*
2090  * Callback from a channel when it can accept more to transmit.
2091  * This should be called at BH/softirq level, not interrupt level.
2092  */
2093 void
2094 ppp_output_wakeup(struct ppp_channel *chan)
2095 {
2096         struct channel *pch = chan->ppp;
2097
2098         if (pch == 0)
2099                 return;
2100         ppp_channel_push(pch);
2101 }
2102
2103 /*
2104  * Compression control.
2105  */
2106
2107 /* Process the PPPIOCSCOMPRESS ioctl. */
2108 static int
2109 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2110 {
2111         int err;
2112         struct compressor *cp, *ocomp;
2113         struct ppp_option_data data;
2114         void *state, *ostate;
2115         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2116
2117         err = -EFAULT;
2118         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2119             || (data.length <= CCP_MAX_OPTION_LENGTH
2120                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2121                 goto out;
2122         err = -EINVAL;
2123         if (data.length > CCP_MAX_OPTION_LENGTH
2124             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2125                 goto out;
2126
2127         cp = find_compressor(ccp_option[0]);
2128 #ifdef CONFIG_KMOD
2129         if (cp == 0) {
2130                 request_module("ppp-compress-%d", ccp_option[0]);
2131                 cp = find_compressor(ccp_option[0]);
2132         }
2133 #endif /* CONFIG_KMOD */
2134         if (cp == 0)
2135                 goto out;
2136
2137         err = -ENOBUFS;
2138         if (data.transmit) {
2139                 state = cp->comp_alloc(ccp_option, data.length);
2140                 if (state != 0) {
2141                         ppp_xmit_lock(ppp);
2142                         ppp->xstate &= ~SC_COMP_RUN;
2143                         ocomp = ppp->xcomp;
2144                         ostate = ppp->xc_state;
2145                         ppp->xcomp = cp;
2146                         ppp->xc_state = state;
2147                         ppp_xmit_unlock(ppp);
2148                         if (ostate != 0) {
2149                                 ocomp->comp_free(ostate);
2150                                 module_put(ocomp->owner);
2151                         }
2152                         err = 0;
2153                 } else
2154                         module_put(cp->owner);
2155
2156         } else {
2157                 state = cp->decomp_alloc(ccp_option, data.length);
2158                 if (state != 0) {
2159                         ppp_recv_lock(ppp);
2160                         ppp->rstate &= ~SC_DECOMP_RUN;
2161                         ocomp = ppp->rcomp;
2162                         ostate = ppp->rc_state;
2163                         ppp->rcomp = cp;
2164                         ppp->rc_state = state;
2165                         ppp_recv_unlock(ppp);
2166                         if (ostate != 0) {
2167                                 ocomp->decomp_free(ostate);
2168                                 module_put(ocomp->owner);
2169                         }
2170                         err = 0;
2171                 } else
2172                         module_put(cp->owner);
2173         }
2174
2175  out:
2176         return err;
2177 }
2178
2179 /*
2180  * Look at a CCP packet and update our state accordingly.
2181  * We assume the caller has the xmit or recv path locked.
2182  */
2183 static void
2184 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2185 {
2186         unsigned char *dp;
2187         int len;
2188
2189         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2190                 return; /* no header */
2191         dp = skb->data + 2;
2192
2193         switch (CCP_CODE(dp)) {
2194         case CCP_CONFREQ:
2195
2196                 /* A ConfReq starts negotiation of compression
2197                  * in one direction of transmission,
2198                  * and hence brings it down...but which way?
2199                  *
2200                  * Remember:
2201                  * A ConfReq indicates what the sender would like to receive
2202                  */
2203                 if(inbound)
2204                         /* He is proposing what I should send */
2205                         ppp->xstate &= ~SC_COMP_RUN;
2206                 else
2207                         /* I am proposing to what he should send */
2208                         ppp->rstate &= ~SC_DECOMP_RUN;
2209
2210                 break;
2211
2212         case CCP_TERMREQ:
2213         case CCP_TERMACK:
2214                 /*
2215                  * CCP is going down, both directions of transmission
2216                  */
2217                 ppp->rstate &= ~SC_DECOMP_RUN;
2218                 ppp->xstate &= ~SC_COMP_RUN;
2219                 break;
2220
2221         case CCP_CONFACK:
2222                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2223                         break;
2224                 len = CCP_LENGTH(dp);
2225                 if (!pskb_may_pull(skb, len + 2))
2226                         return;         /* too short */
2227                 dp += CCP_HDRLEN;
2228                 len -= CCP_HDRLEN;
2229                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2230                         break;
2231                 if (inbound) {
2232                         /* we will start receiving compressed packets */
2233                         if (ppp->rc_state == 0)
2234                                 break;
2235                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2236                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2237                                 ppp->rstate |= SC_DECOMP_RUN;
2238                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2239                         }
2240                 } else {
2241                         /* we will soon start sending compressed packets */
2242                         if (ppp->xc_state == 0)
2243                                 break;
2244                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2245                                         ppp->file.index, 0, ppp->debug))
2246                                 ppp->xstate |= SC_COMP_RUN;
2247                 }
2248                 break;
2249
2250         case CCP_RESETACK:
2251                 /* reset the [de]compressor */
2252                 if ((ppp->flags & SC_CCP_UP) == 0)
2253                         break;
2254                 if (inbound) {
2255                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2256                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2257                                 ppp->rstate &= ~SC_DC_ERROR;
2258                         }
2259                 } else {
2260                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2261                                 ppp->xcomp->comp_reset(ppp->xc_state);
2262                 }
2263                 break;
2264         }
2265 }
2266
2267 /* Free up compression resources. */
2268 static void
2269 ppp_ccp_closed(struct ppp *ppp)
2270 {
2271         void *xstate, *rstate;
2272         struct compressor *xcomp, *rcomp;
2273
2274         ppp_lock(ppp);
2275         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2276         ppp->xstate = 0;
2277         xcomp = ppp->xcomp;
2278         xstate = ppp->xc_state;
2279         ppp->xc_state = NULL;
2280         ppp->rstate = 0;
2281         rcomp = ppp->rcomp;
2282         rstate = ppp->rc_state;
2283         ppp->rc_state = NULL;
2284         ppp_unlock(ppp);
2285
2286         if (xstate) {
2287                 xcomp->comp_free(xstate);
2288                 module_put(xcomp->owner);
2289         }
2290         if (rstate) {
2291                 rcomp->decomp_free(rstate);
2292                 module_put(rcomp->owner);
2293         }
2294 }
2295
2296 /* List of compressors. */
2297 static LIST_HEAD(compressor_list);
2298 static DEFINE_SPINLOCK(compressor_list_lock);
2299
2300 struct compressor_entry {
2301         struct list_head list;
2302         struct compressor *comp;
2303 };
2304
2305 static struct compressor_entry *
2306 find_comp_entry(int proto)
2307 {
2308         struct compressor_entry *ce;
2309
2310         list_for_each_entry(ce, &compressor_list, list) {
2311                 if (ce->comp->compress_proto == proto)
2312                         return ce;
2313         }
2314         return NULL;
2315 }
2316
2317 /* Register a compressor */
2318 int
2319 ppp_register_compressor(struct compressor *cp)
2320 {
2321         struct compressor_entry *ce;
2322         int ret;
2323         spin_lock(&compressor_list_lock);
2324         ret = -EEXIST;
2325         if (find_comp_entry(cp->compress_proto) != 0)
2326                 goto out;
2327         ret = -ENOMEM;
2328         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2329         if (ce == 0)
2330                 goto out;
2331         ret = 0;
2332         ce->comp = cp;
2333         list_add(&ce->list, &compressor_list);
2334  out:
2335         spin_unlock(&compressor_list_lock);
2336         return ret;
2337 }
2338
2339 /* Unregister a compressor */
2340 void
2341 ppp_unregister_compressor(struct compressor *cp)
2342 {
2343         struct compressor_entry *ce;
2344
2345         spin_lock(&compressor_list_lock);
2346         ce = find_comp_entry(cp->compress_proto);
2347         if (ce != 0 && ce->comp == cp) {
2348                 list_del(&ce->list);
2349                 kfree(ce);
2350         }
2351         spin_unlock(&compressor_list_lock);
2352 }
2353
2354 /* Find a compressor. */
2355 static struct compressor *
2356 find_compressor(int type)
2357 {
2358         struct compressor_entry *ce;
2359         struct compressor *cp = NULL;
2360
2361         spin_lock(&compressor_list_lock);
2362         ce = find_comp_entry(type);
2363         if (ce != 0) {
2364                 cp = ce->comp;
2365                 if (!try_module_get(cp->owner))
2366                         cp = NULL;
2367         }
2368         spin_unlock(&compressor_list_lock);
2369         return cp;
2370 }
2371
2372 /*
2373  * Miscelleneous stuff.
2374  */
2375
2376 static void
2377 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2378 {
2379         struct slcompress *vj = ppp->vj;
2380
2381         memset(st, 0, sizeof(*st));
2382         st->p.ppp_ipackets = ppp->stats.rx_packets;
2383         st->p.ppp_ierrors = ppp->stats.rx_errors;
2384         st->p.ppp_ibytes = ppp->stats.rx_bytes;
2385         st->p.ppp_opackets = ppp->stats.tx_packets;
2386         st->p.ppp_oerrors = ppp->stats.tx_errors;
2387         st->p.ppp_obytes = ppp->stats.tx_bytes;
2388         if (vj == 0)
2389                 return;
2390         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2391         st->vj.vjs_compressed = vj->sls_o_compressed;
2392         st->vj.vjs_searches = vj->sls_o_searches;
2393         st->vj.vjs_misses = vj->sls_o_misses;
2394         st->vj.vjs_errorin = vj->sls_i_error;
2395         st->vj.vjs_tossed = vj->sls_i_tossed;
2396         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2397         st->vj.vjs_compressedin = vj->sls_i_compressed;
2398 }
2399
2400 /*
2401  * Stuff for handling the lists of ppp units and channels
2402  * and for initialization.
2403  */
2404
2405 /*
2406  * Create a new ppp interface unit.  Fails if it can't allocate memory
2407  * or if there is already a unit with the requested number.
2408  * unit == -1 means allocate a new number.
2409  */
2410 static struct ppp *
2411 ppp_create_interface(int unit, int *retp)
2412 {
2413         struct ppp *ppp;
2414         struct net_device *dev = NULL;
2415         int ret = -ENOMEM;
2416         int i;
2417
2418         ppp = kzalloc(sizeof(struct ppp), GFP_KERNEL);
2419         if (!ppp)
2420                 goto out;
2421         dev = alloc_netdev(0, "", ppp_setup);
2422         if (!dev)
2423                 goto out1;
2424
2425         ppp->mru = PPP_MRU;
2426         init_ppp_file(&ppp->file, INTERFACE);
2427         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2428         for (i = 0; i < NUM_NP; ++i)
2429                 ppp->npmode[i] = NPMODE_PASS;
2430         INIT_LIST_HEAD(&ppp->channels);
2431         spin_lock_init(&ppp->rlock);
2432         spin_lock_init(&ppp->wlock);
2433 #ifdef CONFIG_PPP_MULTILINK
2434         ppp->minseq = -1;
2435         skb_queue_head_init(&ppp->mrq);
2436 #endif /* CONFIG_PPP_MULTILINK */
2437         ppp->dev = dev;
2438         dev->priv = ppp;
2439
2440         dev->hard_start_xmit = ppp_start_xmit;
2441         dev->get_stats = ppp_net_stats;
2442         dev->do_ioctl = ppp_net_ioctl;
2443
2444         ret = -EEXIST;
2445         mutex_lock(&all_ppp_mutex);
2446         if (unit < 0)
2447                 unit = cardmap_find_first_free(all_ppp_units);
2448         else if (cardmap_get(all_ppp_units, unit) != NULL)
2449                 goto out2;      /* unit already exists */
2450
2451         /* Initialize the new ppp unit */
2452         ppp->file.index = unit;
2453         sprintf(dev->name, "ppp%d", unit);
2454
2455         ret = register_netdev(dev);
2456         if (ret != 0) {
2457                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2458                        dev->name, ret);
2459                 goto out2;
2460         }
2461
2462         atomic_inc(&ppp_unit_count);
2463         ret = cardmap_set(&all_ppp_units, unit, ppp);
2464         if (ret != 0)
2465                 goto out3;
2466
2467         mutex_unlock(&all_ppp_mutex);
2468         *retp = 0;
2469         return ppp;
2470
2471 out3:
2472         atomic_dec(&ppp_unit_count);
2473 out2:
2474         mutex_unlock(&all_ppp_mutex);
2475         free_netdev(dev);
2476 out1:
2477         kfree(ppp);
2478 out:
2479         *retp = ret;
2480         return NULL;
2481 }
2482
2483 /*
2484  * Initialize a ppp_file structure.
2485  */
2486 static void
2487 init_ppp_file(struct ppp_file *pf, int kind)
2488 {
2489         pf->kind = kind;
2490         skb_queue_head_init(&pf->xq);
2491         skb_queue_head_init(&pf->rq);
2492         atomic_set(&pf->refcnt, 1);
2493         init_waitqueue_head(&pf->rwait);
2494 }
2495
2496 /*
2497  * Take down a ppp interface unit - called when the owning file
2498  * (the one that created the unit) is closed or detached.
2499  */
2500 static void ppp_shutdown_interface(struct ppp *ppp)
2501 {
2502         struct net_device *dev;
2503
2504         mutex_lock(&all_ppp_mutex);
2505         ppp_lock(ppp);
2506         dev = ppp->dev;
2507         ppp->dev = NULL;
2508         ppp_unlock(ppp);
2509         /* This will call dev_close() for us. */
2510         if (dev) {
2511                 unregister_netdev(dev);
2512                 free_netdev(dev);
2513         }
2514         cardmap_set(&all_ppp_units, ppp->file.index, NULL);
2515         ppp->file.dead = 1;
2516         ppp->owner = NULL;
2517         wake_up_interruptible(&ppp->file.rwait);
2518         mutex_unlock(&all_ppp_mutex);
2519 }
2520
2521 /*
2522  * Free the memory used by a ppp unit.  This is only called once
2523  * there are no channels connected to the unit and no file structs
2524  * that reference the unit.
2525  */
2526 static void ppp_destroy_interface(struct ppp *ppp)
2527 {
2528         atomic_dec(&ppp_unit_count);
2529
2530         if (!ppp->file.dead || ppp->n_channels) {
2531                 /* "can't happen" */
2532                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2533                        "n_channels=%d !\n", ppp, ppp->file.dead,
2534                        ppp->n_channels);
2535                 return;
2536         }
2537
2538         ppp_ccp_closed(ppp);
2539         if (ppp->vj) {
2540                 slhc_free(ppp->vj);
2541                 ppp->vj = NULL;
2542         }
2543         skb_queue_purge(&ppp->file.xq);
2544         skb_queue_purge(&ppp->file.rq);
2545 #ifdef CONFIG_PPP_MULTILINK
2546         skb_queue_purge(&ppp->mrq);
2547 #endif /* CONFIG_PPP_MULTILINK */
2548 #ifdef CONFIG_PPP_FILTER
2549         kfree(ppp->pass_filter);
2550         ppp->pass_filter = NULL;
2551         kfree(ppp->active_filter);
2552         ppp->active_filter = NULL;
2553 #endif /* CONFIG_PPP_FILTER */
2554
2555         if (ppp->xmit_pending)
2556                 kfree_skb(ppp->xmit_pending);
2557
2558         kfree(ppp);
2559 }
2560
2561 /*
2562  * Locate an existing ppp unit.
2563  * The caller should have locked the all_ppp_mutex.
2564  */
2565 static struct ppp *
2566 ppp_find_unit(int unit)
2567 {
2568         return cardmap_get(all_ppp_units, unit);
2569 }
2570
2571 /*
2572  * Locate an existing ppp channel.
2573  * The caller should have locked the all_channels_lock.
2574  * First we look in the new_channels list, then in the
2575  * all_channels list.  If found in the new_channels list,
2576  * we move it to the all_channels list.  This is for speed
2577  * when we have a lot of channels in use.
2578  */
2579 static struct channel *
2580 ppp_find_channel(int unit)
2581 {
2582         struct channel *pch;
2583
2584         list_for_each_entry(pch, &new_channels, list) {
2585                 if (pch->file.index == unit) {
2586                         list_move(&pch->list, &all_channels);
2587                         return pch;
2588                 }
2589         }
2590         list_for_each_entry(pch, &all_channels, list) {
2591                 if (pch->file.index == unit)
2592                         return pch;
2593         }
2594         return NULL;
2595 }
2596
2597 /*
2598  * Connect a PPP channel to a PPP interface unit.
2599  */
2600 static int
2601 ppp_connect_channel(struct channel *pch, int unit)
2602 {
2603         struct ppp *ppp;
2604         int ret = -ENXIO;
2605         int hdrlen;
2606
2607         mutex_lock(&all_ppp_mutex);
2608         ppp = ppp_find_unit(unit);
2609         if (ppp == 0)
2610                 goto out;
2611         write_lock_bh(&pch->upl);
2612         ret = -EINVAL;
2613         if (pch->ppp != 0)
2614                 goto outl;
2615
2616         ppp_lock(ppp);
2617         if (pch->file.hdrlen > ppp->file.hdrlen)
2618                 ppp->file.hdrlen = pch->file.hdrlen;
2619         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2620         if (ppp->dev && hdrlen > ppp->dev->hard_header_len)
2621                 ppp->dev->hard_header_len = hdrlen;
2622         list_add_tail(&pch->clist, &ppp->channels);
2623         ++ppp->n_channels;
2624         pch->ppp = ppp;
2625         atomic_inc(&ppp->file.refcnt);
2626         ppp_unlock(ppp);
2627         ret = 0;
2628
2629  outl:
2630         write_unlock_bh(&pch->upl);
2631  out:
2632         mutex_unlock(&all_ppp_mutex);
2633         return ret;
2634 }
2635
2636 /*
2637  * Disconnect a channel from its ppp unit.
2638  */
2639 static int
2640 ppp_disconnect_channel(struct channel *pch)
2641 {
2642         struct ppp *ppp;
2643         int err = -EINVAL;
2644
2645         write_lock_bh(&pch->upl);
2646         ppp = pch->ppp;
2647         pch->ppp = NULL;
2648         write_unlock_bh(&pch->upl);
2649         if (ppp != 0) {
2650                 /* remove it from the ppp unit's list */
2651                 ppp_lock(ppp);
2652                 list_del(&pch->clist);
2653                 if (--ppp->n_channels == 0)
2654                         wake_up_interruptible(&ppp->file.rwait);
2655                 ppp_unlock(ppp);
2656                 if (atomic_dec_and_test(&ppp->file.refcnt))
2657                         ppp_destroy_interface(ppp);
2658                 err = 0;
2659         }
2660         return err;
2661 }
2662
2663 /*
2664  * Free up the resources used by a ppp channel.
2665  */
2666 static void ppp_destroy_channel(struct channel *pch)
2667 {
2668         atomic_dec(&channel_count);
2669
2670         if (!pch->file.dead) {
2671                 /* "can't happen" */
2672                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2673                        pch);
2674                 return;
2675         }
2676         skb_queue_purge(&pch->file.xq);
2677         skb_queue_purge(&pch->file.rq);
2678         kfree(pch);
2679 }
2680
2681 static void __exit ppp_cleanup(void)
2682 {
2683         /* should never happen */
2684         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2685                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2686         cardmap_destroy(&all_ppp_units);
2687         unregister_chrdev(PPP_MAJOR, "ppp");
2688         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2689         class_destroy(ppp_class);
2690 }
2691
2692 /*
2693  * Cardmap implementation.
2694  */
2695 static void *cardmap_get(struct cardmap *map, unsigned int nr)
2696 {
2697         struct cardmap *p;
2698         int i;
2699
2700         for (p = map; p != NULL; ) {
2701                 if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
2702                         return NULL;
2703                 if (p->shift == 0)
2704                         return p->ptr[i];
2705                 nr &= ~(CARDMAP_MASK << p->shift);
2706                 p = p->ptr[i];
2707         }
2708         return NULL;
2709 }
2710
2711 static int cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
2712 {
2713         struct cardmap *p;
2714         int i;
2715
2716         p = *pmap;
2717         if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
2718                 do {
2719                         /* need a new top level */
2720                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2721                         if (!np)
2722                                 goto enomem;
2723                         np->ptr[0] = p;
2724                         if (p != NULL) {
2725                                 np->shift = p->shift + CARDMAP_ORDER;
2726                                 p->parent = np;
2727                         } else
2728                                 np->shift = 0;
2729                         p = np;
2730                 } while ((nr >> p->shift) >= CARDMAP_WIDTH);
2731                 *pmap = p;
2732         }
2733         while (p->shift > 0) {
2734                 i = (nr >> p->shift) & CARDMAP_MASK;
2735                 if (p->ptr[i] == NULL) {
2736                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2737                         if (!np)
2738                                 goto enomem;
2739                         np->shift = p->shift - CARDMAP_ORDER;
2740                         np->parent = p;
2741                         p->ptr[i] = np;
2742                 }
2743                 if (ptr == NULL)
2744                         clear_bit(i, &p->inuse);
2745                 p = p->ptr[i];
2746         }
2747         i = nr & CARDMAP_MASK;
2748         p->ptr[i] = ptr;
2749         if (ptr != NULL)
2750                 set_bit(i, &p->inuse);
2751         else
2752                 clear_bit(i, &p->inuse);
2753         return 0;
2754  enomem:
2755         return -ENOMEM;
2756 }
2757
2758 static unsigned int cardmap_find_first_free(struct cardmap *map)
2759 {
2760         struct cardmap *p;
2761         unsigned int nr = 0;
2762         int i;
2763
2764         if ((p = map) == NULL)
2765                 return 0;
2766         for (;;) {
2767                 i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
2768                 if (i >= CARDMAP_WIDTH) {
2769                         if (p->parent == NULL)
2770                                 return CARDMAP_WIDTH << p->shift;
2771                         p = p->parent;
2772                         i = (nr >> p->shift) & CARDMAP_MASK;
2773                         set_bit(i, &p->inuse);
2774                         continue;
2775                 }
2776                 nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
2777                 if (p->shift == 0 || p->ptr[i] == NULL)
2778                         return nr;
2779                 p = p->ptr[i];
2780         }
2781 }
2782
2783 static void cardmap_destroy(struct cardmap **pmap)
2784 {
2785         struct cardmap *p, *np;
2786         int i;
2787
2788         for (p = *pmap; p != NULL; p = np) {
2789                 if (p->shift != 0) {
2790                         for (i = 0; i < CARDMAP_WIDTH; ++i)
2791                                 if (p->ptr[i] != NULL)
2792                                         break;
2793                         if (i < CARDMAP_WIDTH) {
2794                                 np = p->ptr[i];
2795                                 p->ptr[i] = NULL;
2796                                 continue;
2797                         }
2798                 }
2799                 np = p->parent;
2800                 kfree(p);
2801         }
2802         *pmap = NULL;
2803 }
2804
2805 /* Module/initialization stuff */
2806
2807 module_init(ppp_init);
2808 module_exit(ppp_cleanup);
2809
2810 EXPORT_SYMBOL(ppp_register_channel);
2811 EXPORT_SYMBOL(ppp_unregister_channel);
2812 EXPORT_SYMBOL(ppp_channel_index);
2813 EXPORT_SYMBOL(ppp_unit_number);
2814 EXPORT_SYMBOL(ppp_input);
2815 EXPORT_SYMBOL(ppp_input_error);
2816 EXPORT_SYMBOL(ppp_output_wakeup);
2817 EXPORT_SYMBOL(ppp_register_compressor);
2818 EXPORT_SYMBOL(ppp_unregister_compressor);
2819 MODULE_LICENSE("GPL");
2820 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2821 MODULE_ALIAS("/dev/ppp");