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/config.h>
  26 #include <linux/module.h>
  27 #include <linux/kernel.h>
  28 #include <linux/kmod.h>
  29 #include <linux/init.h>
  30 #include <linux/list.h>
  31 #include <linux/devfs_fs_kernel.h>
  32 #include <linux/netdevice.h>
  33 #include <linux/poll.h>
  34 #include <linux/ppp_defs.h>
  35 #include <linux/filter.h>
  36 #include <linux/if_ppp.h>
  37 #include <linux/ppp_channel.h>
  38 #include <linux/ppp-comp.h>
  39 #include <linux/skbuff.h>
  40 #include <linux/rtnetlink.h>
  41 #include <linux/if_arp.h>
  42 #include <linux/ip.h>
  43 #include <linux/tcp.h>
  44 #include <linux/spinlock.h>
  45 #include <linux/smp_lock.h>
  46 #include <linux/rwsem.h>
  47 #include <linux/stddef.h>
  48 #include <linux/device.h>
  49 #include <net/slhc_vj.h>
  50 #include <asm/atomic.h>
  51
  52 #define PPP_VERSION     "2.4.2"
  53
  54 /*
  55  * Network protocols we support.
  56  */
  57 #define NP_IP   0               /* Internet Protocol V4 */
  58 #define NP_IPV6 1               /* Internet Protocol V6 */
  59 #define NP_IPX  2               /* IPX protocol */
  60 #define NP_AT   3               /* Appletalk protocol */
  61 #define NP_MPLS_UC 4            /* MPLS unicast */
  62 #define NP_MPLS_MC 5            /* MPLS multicast */
  63 #define NUM_NP  6               /* Number of NPs. */
  64
  65 #define MPHDRLEN        6       /* multilink protocol header length */
  66 #define MPHDRLEN_SSN    4       /* ditto with short sequence numbers */
  67 #define MIN_FRAG_SIZE   64
  68
  69 /*
  70  * An instance of /dev/ppp can be associated with either a ppp
  71  * interface unit or a ppp channel.  In both cases, file->private_data
  72  * points to one of these.
  73  */
  74 struct ppp_file {
  75         enum {
  76                 INTERFACE=1, CHANNEL
  77         }               kind;
  78         struct sk_buff_head xq;         /* pppd transmit queue */
  79         struct sk_buff_head rq;         /* receive queue for pppd */
  80         wait_queue_head_t rwait;        /* for poll on reading /dev/ppp */
  81         atomic_t        refcnt;         /* # refs (incl /dev/ppp attached) */
  82         int             hdrlen;         /* space to leave for headers */
  83         int             index;          /* interface unit / channel number */
  84         int             dead;           /* unit/channel has been shut down */
  85 };
  86
  87 #define PF_TO_X(pf, X)          ((X *)((char *)(pf) - offsetof(X, file)))
  88
  89 #define PF_TO_PPP(pf)           PF_TO_X(pf, struct ppp)
  90 #define PF_TO_CHANNEL(pf)       PF_TO_X(pf, struct channel)
  91
  92 #define ROUNDUP(n, x)           (((n) + (x) - 1) / (x))
  93
  94 /*
  95  * Data structure describing one ppp unit.
  96  * A ppp unit corresponds to a ppp network interface device
  97  * and represents a multilink bundle.
  98  * It can have 0 or more ppp channels connected to it.
  99  */
 100 struct ppp {
 101         struct ppp_file file;           /* stuff for read/write/poll 0 */
 102         struct file     *owner;         /* file that owns this unit 48 */
 103         struct list_head channels;      /* list of attached channels 4c */
 104         int             n_channels;     /* how many channels are attached 54 */
 105         spinlock_t      rlock;          /* lock for receive side 58 */
 106         spinlock_t      wlock;          /* lock for transmit side 5c */
 107         int             mru;            /* max receive unit 60 */
 108         unsigned int    flags;          /* control bits 64 */
 109         unsigned int    xstate;         /* transmit state bits 68 */
 110         unsigned int    rstate;         /* receive state bits 6c */
 111         int             debug;          /* debug flags 70 */
 112         struct slcompress *vj;          /* state for VJ header compression */
 113         enum NPmode     npmode[NUM_NP]; /* what to do with each net proto 78 */
 114         struct sk_buff  *xmit_pending;  /* a packet ready to go out 88 */
 115         struct compressor *xcomp;       /* transmit packet compressor 8c */
 116         void            *xc_state;      /* its internal state 90 */
 117         struct compressor *rcomp;       /* receive decompressor 94 */
 118         void            *rc_state;      /* its internal state 98 */
 119         unsigned long   last_xmit;      /* jiffies when last pkt sent 9c */
 120         unsigned long   last_recv;      /* jiffies when last pkt rcvd a0 */
 121         struct net_device *dev;         /* network interface device a4 */
 122 #ifdef CONFIG_PPP_MULTILINK
 123         int             nxchan;         /* next channel to send something on */
 124         u32             nxseq;          /* next sequence number to send */
 125         int             mrru;           /* MP: max reconst. receive unit */
 126         u32             nextseq;        /* MP: seq no of next packet */
 127         u32             minseq;         /* MP: min of most recent seqnos */
 128         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
 129 #endif /* CONFIG_PPP_MULTILINK */
 130         struct net_device_stats stats;  /* statistics */
 131 #ifdef CONFIG_PPP_FILTER
 132         struct sock_filter *pass_filter;        /* filter for packets to pass */
 133         struct sock_filter *active_filter;/* filter for pkts to reset idle */
 134         unsigned pass_len, active_len;
 135 #endif /* CONFIG_PPP_FILTER */
 136 };
 137
 138 /*
 139  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
 140  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
 141  * SC_MUST_COMP
 142  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
 143  * Bits in xstate: SC_COMP_RUN
 144  */
 145 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
 146                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
 147                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
 148
 149 /*
 150  * Private data structure for each channel.
 151  * This includes the data structure used for multilink.
 152  */
 153 struct channel {
 154         struct ppp_file file;           /* stuff for read/write/poll */
 155         struct list_head list;          /* link in all/new_channels list */
 156         struct ppp_channel *chan;       /* public channel data structure */
 157         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
 158         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
 159         struct ppp      *ppp;           /* ppp unit we're connected to */
 160         struct list_head clist;         /* link in list of channels per unit */
 161         rwlock_t        upl;            /* protects `ppp' */
 162 #ifdef CONFIG_PPP_MULTILINK
 163         u8              avail;          /* flag used in multilink stuff */
 164         u8              had_frag;       /* >= 1 fragments have been sent */
 165         u32             lastseq;        /* MP: last sequence # received */
 166 #endif /* CONFIG_PPP_MULTILINK */
 167 };
 168
 169 /*
 170  * SMP locking issues:
 171  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
 172  * list and the ppp.n_channels field, you need to take both locks
 173  * before you modify them.
 174  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
 175  * channel.downl.
 176  */
 177
 178 /*
 179  * A cardmap represents a mapping from unsigned integers to pointers,
 180  * and provides a fast "find lowest unused number" operation.
 181  * It uses a broad (32-way) tree with a bitmap at each level.
 182  * It is designed to be space-efficient for small numbers of entries
 183  * and time-efficient for large numbers of entries.
 184  */
 185 #define CARDMAP_ORDER   5
 186 #define CARDMAP_WIDTH   (1U << CARDMAP_ORDER)
 187 #define CARDMAP_MASK    (CARDMAP_WIDTH - 1)
 188
 189 struct cardmap {
 190         int shift;
 191         unsigned long inuse;
 192         struct cardmap *parent;
 193         void *ptr[CARDMAP_WIDTH];
 194 };
 195 static void *cardmap_get(struct cardmap *map, unsigned int nr);
 196 static void cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
 197 static unsigned int cardmap_find_first_free(struct cardmap *map);
 198 static void cardmap_destroy(struct cardmap **map);
 199
 200 /*
 201  * all_ppp_sem protects the all_ppp_units mapping.
 202  * It also ensures that finding a ppp unit in the all_ppp_units map
 203  * and updating its file.refcnt field is atomic.
 204  */
 205 static DECLARE_MUTEX(all_ppp_sem);
 206 static struct cardmap *all_ppp_units;
 207 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 208
 209 /*
 210  * all_channels_lock protects all_channels and last_channel_index,
 211  * and the atomicity of find a channel and updating its file.refcnt
 212  * field.
 213  */
 214 static DEFINE_SPINLOCK(all_channels_lock);
 215 static LIST_HEAD(all_channels);
 216 static LIST_HEAD(new_channels);
 217 static int last_channel_index;
 218 static atomic_t channel_count = ATOMIC_INIT(0);
 219
 220 /* Get the PPP protocol number from a skb */
 221 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
 222
 223 /* We limit the length of ppp->file.rq to this (arbitrary) value */
 224 #define PPP_MAX_RQLEN   32
 225
 226 /*
 227  * Maximum number of multilink fragments queued up.
 228  * This has to be large enough to cope with the maximum latency of
 229  * the slowest channel relative to the others.  Strictly it should
 230  * depend on the number of channels and their characteristics.
 231  */
 232 #define PPP_MP_MAX_QLEN 128
 233
 234 /* Multilink header bits. */
 235 #define B       0x80            /* this fragment begins a packet */
 236 #define E       0x40            /* this fragment ends a packet */
 237
 238 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
 239 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
 240 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
 241
 242 /* Prototypes. */
 243 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 244                                 unsigned int cmd, unsigned long arg);
 245 static void ppp_xmit_process(struct ppp *ppp);
 246 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
 247 static void ppp_push(struct ppp *ppp);
 248 static void ppp_channel_push(struct channel *pch);
 249 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
 250                               struct channel *pch);
 251 static void ppp_receive_error(struct ppp *ppp);
 252 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
 253 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
 254                                             struct sk_buff *skb);
 255 #ifdef CONFIG_PPP_MULTILINK
 256 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
 257                                 struct channel *pch);
 258 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
 259 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
 260 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
 261 #endif /* CONFIG_PPP_MULTILINK */
 262 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
 263 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
 264 static void ppp_ccp_closed(struct ppp *ppp);
 265 static struct compressor *find_compressor(int type);
 266 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
 267 static struct ppp *ppp_create_interface(int unit, int *retp);
 268 static void init_ppp_file(struct ppp_file *pf, int kind);
 269 static void ppp_shutdown_interface(struct ppp *ppp);
 270 static void ppp_destroy_interface(struct ppp *ppp);
 271 static struct ppp *ppp_find_unit(int unit);
 272 static struct channel *ppp_find_channel(int unit);
 273 static int ppp_connect_channel(struct channel *pch, int unit);
 274 static int ppp_disconnect_channel(struct channel *pch);
 275 static void ppp_destroy_channel(struct channel *pch);
 276
 277 static struct class *ppp_class;
 278
 279 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
 280 static inline int proto_to_npindex(int proto)
 281 {
 282         switch (proto) {
 283         case PPP_IP:
 284                 return NP_IP;
 285         case PPP_IPV6:
 286                 return NP_IPV6;
 287         case PPP_IPX:
 288                 return NP_IPX;
 289         case PPP_AT:
 290                 return NP_AT;
 291         case PPP_MPLS_UC:
 292                 return NP_MPLS_UC;
 293         case PPP_MPLS_MC:
 294                 return NP_MPLS_MC;
 295         }
 296         return -EINVAL;
 297 }
 298
 299 /* Translates an NP index into a PPP protocol number */
 300 static const int npindex_to_proto[NUM_NP] = {
 301         PPP_IP,
 302         PPP_IPV6,
 303         PPP_IPX,
 304         PPP_AT,
 305         PPP_MPLS_UC,
 306         PPP_MPLS_MC,
 307 };
 308
 309 /* Translates an ethertype into an NP index */
 310 static inline int ethertype_to_npindex(int ethertype)
 311 {
 312         switch (ethertype) {
 313         case ETH_P_IP:
 314                 return NP_IP;
 315         case ETH_P_IPV6:
 316                 return NP_IPV6;
 317         case ETH_P_IPX:
 318                 return NP_IPX;
 319         case ETH_P_PPPTALK:
 320         case ETH_P_ATALK:
 321                 return NP_AT;
 322         case ETH_P_MPLS_UC:
 323                 return NP_MPLS_UC;
 324         case ETH_P_MPLS_MC:
 325                 return NP_MPLS_MC;
 326         }
 327         return -1;
 328 }
 329
 330 /* Translates an NP index into an ethertype */
 331 static const int npindex_to_ethertype[NUM_NP] = {
 332         ETH_P_IP,
 333         ETH_P_IPV6,
 334         ETH_P_IPX,
 335         ETH_P_PPPTALK,
 336         ETH_P_MPLS_UC,
 337         ETH_P_MPLS_MC,
 338 };
 339
 340 /*
 341  * Locking shorthand.
 342  */
 343 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
 344 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
 345 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
 346 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
 347 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
 348                                      ppp_recv_lock(ppp); } while (0)
 349 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
 350                                      ppp_xmit_unlock(ppp); } while (0)
 351
 352 /*
 353  * /dev/ppp device routines.
 354  * The /dev/ppp device is used by pppd to control the ppp unit.
 355  * It supports the read, write, ioctl and poll functions.
 356  * Open instances of /dev/ppp can be in one of three states:
 357  * unattached, attached to a ppp unit, or attached to a ppp channel.
 358  */
 359 static int ppp_open(struct inode *inode, struct file *file)
 360 {
 361         /*
 362          * This could (should?) be enforced by the permissions on /dev/ppp.
 363          */
 364         if (!capable(CAP_NET_ADMIN))
 365                 return -EPERM;
 366         return 0;
 367 }
 368
 369 static int ppp_release(struct inode *inode, struct file *file)
 370 {
 371         struct ppp_file *pf = file->private_data;
 372         struct ppp *ppp;
 373
 374         if (pf != 0) {
 375                 file->private_data = NULL;
 376                 if (pf->kind == INTERFACE) {
 377                         ppp = PF_TO_PPP(pf);
 378                         if (file == ppp->owner)
 379                                 ppp_shutdown_interface(ppp);
 380                 }
 381                 if (atomic_dec_and_test(&pf->refcnt)) {
 382                         switch (pf->kind) {
 383                         case INTERFACE:
 384                                 ppp_destroy_interface(PF_TO_PPP(pf));
 385                                 break;
 386                         case CHANNEL:
 387                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
 388                                 break;
 389                         }
 390                 }
 391         }
 392         return 0;
 393 }
 394
 395 static ssize_t ppp_read(struct file *file, char __user *buf,
 396                         size_t count, loff_t *ppos)
 397 {
 398         struct ppp_file *pf = file->private_data;
 399         DECLARE_WAITQUEUE(wait, current);
 400         ssize_t ret;
 401         struct sk_buff *skb = NULL;
 402
 403         ret = count;
 404
 405         if (pf == 0)
 406                 return -ENXIO;
 407         add_wait_queue(&pf->rwait, &wait);
 408         for (;;) {
 409                 set_current_state(TASK_INTERRUPTIBLE);
 410                 skb = skb_dequeue(&pf->rq);
 411                 if (skb)
 412                         break;
 413                 ret = 0;
 414                 if (pf->dead)
 415                         break;
 416                 if (pf->kind == INTERFACE) {
 417                         /*
 418                          * Return 0 (EOF) on an interface that has no
 419                          * channels connected, unless it is looping
 420                          * network traffic (demand mode).
 421                          */
 422                         struct ppp *ppp = PF_TO_PPP(pf);
 423                         if (ppp->n_channels == 0
 424                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 425                                 break;
 426                 }
 427                 ret = -EAGAIN;
 428                 if (file->f_flags & O_NONBLOCK)
 429                         break;
 430                 ret = -ERESTARTSYS;
 431                 if (signal_pending(current))
 432                         break;
 433                 schedule();
 434         }
 435         set_current_state(TASK_RUNNING);
 436         remove_wait_queue(&pf->rwait, &wait);
 437
 438         if (skb == 0)
 439                 goto out;
 440
 441         ret = -EOVERFLOW;
 442         if (skb->len > count)
 443                 goto outf;
 444         ret = -EFAULT;
 445         if (copy_to_user(buf, skb->data, skb->len))
 446                 goto outf;
 447         ret = skb->len;
 448
 449  outf:
 450         kfree_skb(skb);
 451  out:
 452         return ret;
 453 }
 454
 455 static ssize_t ppp_write(struct file *file, const char __user *buf,
 456                          size_t count, loff_t *ppos)
 457 {
 458         struct ppp_file *pf = file->private_data;
 459         struct sk_buff *skb;
 460         ssize_t ret;
 461
 462         if (pf == 0)
 463                 return -ENXIO;
 464         ret = -ENOMEM;
 465         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
 466         if (skb == 0)
 467                 goto out;
 468         skb_reserve(skb, pf->hdrlen);
 469         ret = -EFAULT;
 470         if (copy_from_user(skb_put(skb, count), buf, count)) {
 471                 kfree_skb(skb);
 472                 goto out;
 473         }
 474
 475         skb_queue_tail(&pf->xq, skb);
 476
 477         switch (pf->kind) {
 478         case INTERFACE:
 479                 ppp_xmit_process(PF_TO_PPP(pf));
 480                 break;
 481         case CHANNEL:
 482                 ppp_channel_push(PF_TO_CHANNEL(pf));
 483                 break;
 484         }
 485
 486         ret = count;
 487
 488  out:
 489         return ret;
 490 }
 491
 492 /* No kernel lock - fine */
 493 static unsigned int ppp_poll(struct file *file, poll_table *wait)
 494 {
 495         struct ppp_file *pf = file->private_data;
 496         unsigned int mask;
 497
 498         if (pf == 0)
 499                 return 0;
 500         poll_wait(file, &pf->rwait, wait);
 501         mask = POLLOUT | POLLWRNORM;
 502         if (skb_peek(&pf->rq) != 0)
 503                 mask |= POLLIN | POLLRDNORM;
 504         if (pf->dead)
 505                 mask |= POLLHUP;
 506         else if (pf->kind == INTERFACE) {
 507                 /* see comment in ppp_read */
 508                 struct ppp *ppp = PF_TO_PPP(pf);
 509                 if (ppp->n_channels == 0
 510                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 511                         mask |= POLLIN | POLLRDNORM;
 512         }
 513
 514         return mask;
 515 }
 516
 517 #ifdef CONFIG_PPP_FILTER
 518 static int get_filter(void __user *arg, struct sock_filter **p)
 519 {
 520         struct sock_fprog uprog;
 521         struct sock_filter *code = NULL;
 522         int len, err;
 523
 524         if (copy_from_user(&uprog, arg, sizeof(uprog)))
 525                 return -EFAULT;
 526
 527         if (!uprog.len) {
 528                 *p = NULL;
 529                 return 0;
 530         }
 531
 532         len = uprog.len * sizeof(struct sock_filter);
 533         code = kmalloc(len, GFP_KERNEL);
 534         if (code == NULL)
 535                 return -ENOMEM;
 536
 537         if (copy_from_user(code, uprog.filter, len)) {
 538                 kfree(code);
 539                 return -EFAULT;
 540         }
 541
 542         err = sk_chk_filter(code, uprog.len);
 543         if (err) {
 544                 kfree(code);
 545                 return err;
 546         }
 547
 548         *p = code;
 549         return uprog.len;
 550 }
 551 #endif /* CONFIG_PPP_FILTER */
 552
 553 static int ppp_ioctl(struct inode *inode, struct file *file,
 554                      unsigned int cmd, unsigned long arg)
 555 {
 556         struct ppp_file *pf = file->private_data;
 557         struct ppp *ppp;
 558         int err = -EFAULT, val, val2, i;
 559         struct ppp_idle idle;
 560         struct npioctl npi;
 561         int unit, cflags;
 562         struct slcompress *vj;
 563         void __user *argp = (void __user *)arg;
 564         int __user *p = argp;
 565
 566         if (pf == 0)
 567                 return ppp_unattached_ioctl(pf, file, cmd, arg);
 568
 569         if (cmd == PPPIOCDETACH) {
 570                 /*
 571                  * We have to be careful here... if the file descriptor
 572                  * has been dup'd, we could have another process in the
 573                  * middle of a poll using the same file *, so we had
 574                  * better not free the interface data structures -
 575                  * instead we fail the ioctl.  Even in this case, we
 576                  * shut down the interface if we are the owner of it.
 577                  * Actually, we should get rid of PPPIOCDETACH, userland
 578                  * (i.e. pppd) could achieve the same effect by closing
 579                  * this fd and reopening /dev/ppp.
 580                  */
 581                 err = -EINVAL;
 582                 if (pf->kind == INTERFACE) {
 583                         ppp = PF_TO_PPP(pf);
 584                         if (file == ppp->owner)
 585                                 ppp_shutdown_interface(ppp);
 586                 }
 587                 if (atomic_read(&file->f_count) <= 2) {
 588                         ppp_release(inode, file);
 589                         err = 0;
 590                 } else
 591                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%d\n",
 592                                atomic_read(&file->f_count));
 593                 return err;
 594         }
 595
 596         if (pf->kind == CHANNEL) {
 597                 struct channel *pch = PF_TO_CHANNEL(pf);
 598                 struct ppp_channel *chan;
 599
 600                 switch (cmd) {
 601                 case PPPIOCCONNECT:
 602                         if (get_user(unit, p))
 603                                 break;
 604                         err = ppp_connect_channel(pch, unit);
 605                         break;
 606
 607                 case PPPIOCDISCONN:
 608                         err = ppp_disconnect_channel(pch);
 609                         break;
 610
 611                 default:
 612                         down_read(&pch->chan_sem);
 613                         chan = pch->chan;
 614                         err = -ENOTTY;
 615                         if (chan && chan->ops->ioctl)
 616                                 err = chan->ops->ioctl(chan, cmd, arg);
 617                         up_read(&pch->chan_sem);
 618                 }
 619                 return err;
 620         }
 621
 622         if (pf->kind != INTERFACE) {
 623                 /* can't happen */
 624                 printk(KERN_ERR "PPP: not interface or channel??\n");
 625                 return -EINVAL;
 626         }
 627
 628         ppp = PF_TO_PPP(pf);
 629         switch (cmd) {
 630         case PPPIOCSMRU:
 631                 if (get_user(val, p))
 632                         break;
 633                 ppp->mru = val;
 634                 err = 0;
 635                 break;
 636
 637         case PPPIOCSFLAGS:
 638                 if (get_user(val, p))
 639                         break;
 640                 ppp_lock(ppp);
 641                 cflags = ppp->flags & ~val;
 642                 ppp->flags = val & SC_FLAG_BITS;
 643                 ppp_unlock(ppp);
 644                 if (cflags & SC_CCP_OPEN)
 645                         ppp_ccp_closed(ppp);
 646                 err = 0;
 647                 break;
 648
 649         case PPPIOCGFLAGS:
 650                 val = ppp->flags | ppp->xstate | ppp->rstate;
 651                 if (put_user(val, p))
 652                         break;
 653                 err = 0;
 654                 break;
 655
 656         case PPPIOCSCOMPRESS:
 657                 err = ppp_set_compress(ppp, arg);
 658                 break;
 659
 660         case PPPIOCGUNIT:
 661                 if (put_user(ppp->file.index, p))
 662                         break;
 663                 err = 0;
 664                 break;
 665
 666         case PPPIOCSDEBUG:
 667                 if (get_user(val, p))
 668                         break;
 669                 ppp->debug = val;
 670                 err = 0;
 671                 break;
 672
 673         case PPPIOCGDEBUG:
 674                 if (put_user(ppp->debug, p))
 675                         break;
 676                 err = 0;
 677                 break;
 678
 679         case PPPIOCGIDLE:
 680                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 681                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
 682                 if (copy_to_user(argp, &idle, sizeof(idle)))
 683                         break;
 684                 err = 0;
 685                 break;
 686
 687         case PPPIOCSMAXCID:
 688                 if (get_user(val, p))
 689                         break;
 690                 val2 = 15;
 691                 if ((val >> 16) != 0) {
 692                         val2 = val >> 16;
 693                         val &= 0xffff;
 694                 }
 695                 vj = slhc_init(val2+1, val+1);
 696                 if (vj == 0) {
 697                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
 698                         err = -ENOMEM;
 699                         break;
 700                 }
 701                 ppp_lock(ppp);
 702                 if (ppp->vj != 0)
 703                         slhc_free(ppp->vj);
 704                 ppp->vj = vj;
 705                 ppp_unlock(ppp);
 706                 err = 0;
 707                 break;
 708
 709         case PPPIOCGNPMODE:
 710         case PPPIOCSNPMODE:
 711                 if (copy_from_user(&npi, argp, sizeof(npi)))
 712                         break;
 713                 err = proto_to_npindex(npi.protocol);
 714                 if (err < 0)
 715                         break;
 716                 i = err;
 717                 if (cmd == PPPIOCGNPMODE) {
 718                         err = -EFAULT;
 719                         npi.mode = ppp->npmode[i];
 720                         if (copy_to_user(argp, &npi, sizeof(npi)))
 721                                 break;
 722                 } else {
 723                         ppp->npmode[i] = npi.mode;
 724                         /* we may be able to transmit more packets now (??) */
 725                         netif_wake_queue(ppp->dev);
 726                 }
 727                 err = 0;
 728                 break;
 729
 730 #ifdef CONFIG_PPP_FILTER
 731         case PPPIOCSPASS:
 732         {
 733                 struct sock_filter *code;
 734                 err = get_filter(argp, &code);
 735                 if (err >= 0) {
 736                         ppp_lock(ppp);
 737                         kfree(ppp->pass_filter);
 738                         ppp->pass_filter = code;
 739                         ppp->pass_len = err;
 740                         ppp_unlock(ppp);
 741                         err = 0;
 742                 }
 743                 break;
 744         }
 745         case PPPIOCSACTIVE:
 746         {
 747                 struct sock_filter *code;
 748                 err = get_filter(argp, &code);
 749                 if (err >= 0) {
 750                         ppp_lock(ppp);
 751                         kfree(ppp->active_filter);
 752                         ppp->active_filter = code;
 753                         ppp->active_len = err;
 754                         ppp_unlock(ppp);
 755                         err = 0;
 756                 }
 757                 break;
 758         }
 759 #endif /* CONFIG_PPP_FILTER */
 760
 761 #ifdef CONFIG_PPP_MULTILINK
 762         case PPPIOCSMRRU:
 763                 if (get_user(val, p))
 764                         break;
 765                 ppp_recv_lock(ppp);
 766                 ppp->mrru = val;
 767                 ppp_recv_unlock(ppp);
 768                 err = 0;
 769                 break;
 770 #endif /* CONFIG_PPP_MULTILINK */
 771
 772         default:
 773                 err = -ENOTTY;
 774         }
 775
 776         return err;
 777 }
 778
 779 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 780                                 unsigned int cmd, unsigned long arg)
 781 {
 782         int unit, err = -EFAULT;
 783         struct ppp *ppp;
 784         struct channel *chan;
 785         int __user *p = (int __user *)arg;
 786
 787         switch (cmd) {
 788         case PPPIOCNEWUNIT:
 789                 /* Create a new ppp unit */
 790                 if (get_user(unit, p))
 791                         break;
 792                 ppp = ppp_create_interface(unit, &err);
 793                 if (ppp == 0)
 794                         break;
 795                 file->private_data = &ppp->file;
 796                 ppp->owner = file;
 797                 err = -EFAULT;
 798                 if (put_user(ppp->file.index, p))
 799                         break;
 800                 err = 0;
 801                 break;
 802
 803         case PPPIOCATTACH:
 804                 /* Attach to an existing ppp unit */
 805                 if (get_user(unit, p))
 806                         break;
 807                 down(&all_ppp_sem);
 808                 err = -ENXIO;
 809                 ppp = ppp_find_unit(unit);
 810                 if (ppp != 0) {
 811                         atomic_inc(&ppp->file.refcnt);
 812                         file->private_data = &ppp->file;
 813                         err = 0;
 814                 }
 815                 up(&all_ppp_sem);
 816                 break;
 817
 818         case PPPIOCATTCHAN:
 819                 if (get_user(unit, p))
 820                         break;
 821                 spin_lock_bh(&all_channels_lock);
 822                 err = -ENXIO;
 823                 chan = ppp_find_channel(unit);
 824                 if (chan != 0) {
 825                         atomic_inc(&chan->file.refcnt);
 826                         file->private_data = &chan->file;
 827                         err = 0;
 828                 }
 829                 spin_unlock_bh(&all_channels_lock);
 830                 break;
 831
 832         default:
 833                 err = -ENOTTY;
 834         }
 835         return err;
 836 }
 837
 838 static struct file_operations ppp_device_fops = {
 839         .owner          = THIS_MODULE,
 840         .read           = ppp_read,
 841         .write          = ppp_write,
 842         .poll           = ppp_poll,
 843         .ioctl          = ppp_ioctl,
 844         .open           = ppp_open,
 845         .release        = ppp_release
 846 };
 847
 848 #define PPP_MAJOR       108
 849
 850 /* Called at boot time if ppp is compiled into the kernel,
 851    or at module load time (from init_module) if compiled as a module. */
 852 static int __init ppp_init(void)
 853 {
 854         int err;
 855
 856         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
 857         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
 858         if (!err) {
 859                 ppp_class = class_create(THIS_MODULE, "ppp");
 860                 if (IS_ERR(ppp_class)) {
 861                         err = PTR_ERR(ppp_class);
 862                         goto out_chrdev;
 863                 }
 864                 class_device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL, "ppp");
 865                 err = devfs_mk_cdev(MKDEV(PPP_MAJOR, 0),
 866                                 S_IFCHR|S_IRUSR|S_IWUSR, "ppp");
 867                 if (err)
 868                         goto out_class;
 869         }
 870
 871 out:
 872         if (err)
 873                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
 874         return err;
 875
 876 out_class:
 877         class_device_destroy(ppp_class, MKDEV(PPP_MAJOR,0));
 878         class_destroy(ppp_class);
 879 out_chrdev:
 880         unregister_chrdev(PPP_MAJOR, "ppp");
 881         goto out;
 882 }
 883
 884 /*
 885  * Network interface unit routines.
 886  */
 887 static int
 888 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 889 {
 890         struct ppp *ppp = (struct ppp *) dev->priv;
 891         int npi, proto;
 892         unsigned char *pp;
 893
 894         npi = ethertype_to_npindex(ntohs(skb->protocol));
 895         if (npi < 0)
 896                 goto outf;
 897
 898         /* Drop, accept or reject the packet */
 899         switch (ppp->npmode[npi]) {
 900         case NPMODE_PASS:
 901                 break;
 902         case NPMODE_QUEUE:
 903                 /* it would be nice to have a way to tell the network
 904                    system to queue this one up for later. */
 905                 goto outf;
 906         case NPMODE_DROP:
 907         case NPMODE_ERROR:
 908                 goto outf;
 909         }
 910
 911         /* Put the 2-byte PPP protocol number on the front,
 912            making sure there is room for the address and control fields. */
 913         if (skb_headroom(skb) < PPP_HDRLEN) {
 914                 struct sk_buff *ns;
 915
 916                 ns = alloc_skb(skb->len + dev->hard_header_len, GFP_ATOMIC);
 917                 if (ns == 0)
 918                         goto outf;
 919                 skb_reserve(ns, dev->hard_header_len);
 920                 skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
 921                 kfree_skb(skb);
 922                 skb = ns;
 923         }
 924         pp = skb_push(skb, 2);
 925         proto = npindex_to_proto[npi];
 926         pp[0] = proto >> 8;
 927         pp[1] = proto;
 928
 929         netif_stop_queue(dev);
 930         skb_queue_tail(&ppp->file.xq, skb);
 931         ppp_xmit_process(ppp);
 932         return 0;
 933
 934  outf:
 935         kfree_skb(skb);
 936         ++ppp->stats.tx_dropped;
 937         return 0;
 938 }
 939
 940 static struct net_device_stats *
 941 ppp_net_stats(struct net_device *dev)
 942 {
 943         struct ppp *ppp = (struct ppp *) dev->priv;
 944
 945         return &ppp->stats;
 946 }
 947
 948 static int
 949 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 950 {
 951         struct ppp *ppp = dev->priv;
 952         int err = -EFAULT;
 953         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
 954         struct ppp_stats stats;
 955         struct ppp_comp_stats cstats;
 956         char *vers;
 957
 958         switch (cmd) {
 959         case SIOCGPPPSTATS:
 960                 ppp_get_stats(ppp, &stats);
 961                 if (copy_to_user(addr, &stats, sizeof(stats)))
 962                         break;
 963                 err = 0;
 964                 break;
 965
 966         case SIOCGPPPCSTATS:
 967                 memset(&cstats, 0, sizeof(cstats));
 968                 if (ppp->xc_state != 0)
 969                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
 970                 if (ppp->rc_state != 0)
 971                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
 972                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
 973                         break;
 974                 err = 0;
 975                 break;
 976
 977         case SIOCGPPPVER:
 978                 vers = PPP_VERSION;
 979                 if (copy_to_user(addr, vers, strlen(vers) + 1))
 980                         break;
 981                 err = 0;
 982                 break;
 983
 984         default:
 985                 err = -EINVAL;
 986         }
 987
 988         return err;
 989 }
 990
 991 static void ppp_setup(struct net_device *dev)
 992 {
 993         dev->hard_header_len = PPP_HDRLEN;
 994         dev->mtu = PPP_MTU;
 995         dev->addr_len = 0;
 996         dev->tx_queue_len = 3;
 997         dev->type = ARPHRD_PPP;
 998         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
 999 }
1000
1001 /*
1002  * Transmit-side routines.
1003  */
1004
1005 /*
1006  * Called to do any work queued up on the transmit side
1007  * that can now be done.
1008  */
1009 static void
1010 ppp_xmit_process(struct ppp *ppp)
1011 {
1012         struct sk_buff *skb;
1013
1014         ppp_xmit_lock(ppp);
1015         if (ppp->dev != 0) {
1016                 ppp_push(ppp);
1017                 while (ppp->xmit_pending == 0
1018                        && (skb = skb_dequeue(&ppp->file.xq)) != 0)
1019                         ppp_send_frame(ppp, skb);
1020                 /* If there's no work left to do, tell the core net
1021                    code that we can accept some more. */
1022                 if (ppp->xmit_pending == 0 && skb_peek(&ppp->file.xq) == 0)
1023                         netif_wake_queue(ppp->dev);
1024         }
1025         ppp_xmit_unlock(ppp);
1026 }
1027
1028 static inline struct sk_buff *
1029 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1030 {
1031         struct sk_buff *new_skb;
1032         int len;
1033         int new_skb_size = ppp->dev->mtu +
1034                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1035         int compressor_skb_size = ppp->dev->mtu +
1036                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1037         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1038         if (!new_skb) {
1039                 if (net_ratelimit())
1040                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1041                 return NULL;
1042         }
1043         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1044                 skb_reserve(new_skb,
1045                             ppp->dev->hard_header_len - PPP_HDRLEN);
1046
1047         /* compressor still expects A/C bytes in hdr */
1048         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1049                                    new_skb->data, skb->len + 2,
1050                                    compressor_skb_size);
1051         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1052                 kfree_skb(skb);
1053                 skb = new_skb;
1054                 skb_put(skb, len);
1055                 skb_pull(skb, 2);       /* pull off A/C bytes */
1056         } else if (len == 0) {
1057                 /* didn't compress, or CCP not up yet */
1058                 kfree_skb(new_skb);
1059                 new_skb = skb;
1060         } else {
1061                 /*
1062                  * (len < 0)
1063                  * MPPE requires that we do not send unencrypted
1064                  * frames.  The compressor will return -1 if we
1065                  * should drop the frame.  We cannot simply test
1066                  * the compress_proto because MPPE and MPPC share
1067                  * the same number.
1068                  */
1069                 if (net_ratelimit())
1070                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1071                 kfree_skb(skb);
1072                 kfree_skb(new_skb);
1073                 new_skb = NULL;
1074         }
1075         return new_skb;
1076 }
1077
1078 /*
1079  * Compress and send a frame.
1080  * The caller should have locked the xmit path,
1081  * and xmit_pending should be 0.
1082  */
1083 static void
1084 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1085 {
1086         int proto = PPP_PROTO(skb);
1087         struct sk_buff *new_skb;
1088         int len;
1089         unsigned char *cp;
1090
1091         if (proto < 0x8000) {
1092 #ifdef CONFIG_PPP_FILTER
1093                 /* check if we should pass this packet */
1094                 /* the filter instructions are constructed assuming
1095                    a four-byte PPP header on each packet */
1096                 *skb_push(skb, 2) = 1;
1097                 if (ppp->pass_filter
1098                     && sk_run_filter(skb, ppp->pass_filter,
1099                                      ppp->pass_len) == 0) {
1100                         if (ppp->debug & 1)
1101                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1102                         kfree_skb(skb);
1103                         return;
1104                 }
1105                 /* if this packet passes the active filter, record the time */
1106                 if (!(ppp->active_filter
1107                       && sk_run_filter(skb, ppp->active_filter,
1108                                        ppp->active_len) == 0))
1109                         ppp->last_xmit = jiffies;
1110                 skb_pull(skb, 2);
1111 #else
1112                 /* for data packets, record the time */
1113                 ppp->last_xmit = jiffies;
1114 #endif /* CONFIG_PPP_FILTER */
1115         }
1116
1117         ++ppp->stats.tx_packets;
1118         ppp->stats.tx_bytes += skb->len - 2;
1119
1120         switch (proto) {
1121         case PPP_IP:
1122                 if (ppp->vj == 0 || (ppp->flags & SC_COMP_TCP) == 0)
1123                         break;
1124                 /* try to do VJ TCP header compression */
1125                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1126                                     GFP_ATOMIC);
1127                 if (new_skb == 0) {
1128                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1129                         goto drop;
1130                 }
1131                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1132                 cp = skb->data + 2;
1133                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1134                                     new_skb->data + 2, &cp,
1135                                     !(ppp->flags & SC_NO_TCP_CCID));
1136                 if (cp == skb->data + 2) {
1137                         /* didn't compress */
1138                         kfree_skb(new_skb);
1139                 } else {
1140                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1141                                 proto = PPP_VJC_COMP;
1142                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1143                         } else {
1144                                 proto = PPP_VJC_UNCOMP;
1145                                 cp[0] = skb->data[2];
1146                         }
1147                         kfree_skb(skb);
1148                         skb = new_skb;
1149                         cp = skb_put(skb, len + 2);
1150                         cp[0] = 0;
1151                         cp[1] = proto;
1152                 }
1153                 break;
1154
1155         case PPP_CCP:
1156                 /* peek at outbound CCP frames */
1157                 ppp_ccp_peek(ppp, skb, 0);
1158                 break;
1159         }
1160
1161         /* try to do packet compression */
1162         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0
1163             && proto != PPP_LCP && proto != PPP_CCP) {
1164                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1165                         if (net_ratelimit())
1166                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1167                         goto drop;
1168                 }
1169                 skb = pad_compress_skb(ppp, skb);
1170                 if (!skb)
1171                         goto drop;
1172         }
1173
1174         /*
1175          * If we are waiting for traffic (demand dialling),
1176          * queue it up for pppd to receive.
1177          */
1178         if (ppp->flags & SC_LOOP_TRAFFIC) {
1179                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1180                         goto drop;
1181                 skb_queue_tail(&ppp->file.rq, skb);
1182                 wake_up_interruptible(&ppp->file.rwait);
1183                 return;
1184         }
1185
1186         ppp->xmit_pending = skb;
1187         ppp_push(ppp);
1188         return;
1189
1190  drop:
1191         if (skb)
1192                 kfree_skb(skb);
1193         ++ppp->stats.tx_errors;
1194 }
1195
1196 /*
1197  * Try to send the frame in xmit_pending.
1198  * The caller should have the xmit path locked.
1199  */
1200 static void
1201 ppp_push(struct ppp *ppp)
1202 {
1203         struct list_head *list;
1204         struct channel *pch;
1205         struct sk_buff *skb = ppp->xmit_pending;
1206
1207         if (skb == 0)
1208                 return;
1209
1210         list = &ppp->channels;
1211         if (list_empty(list)) {
1212                 /* nowhere to send the packet, just drop it */
1213                 ppp->xmit_pending = NULL;
1214                 kfree_skb(skb);
1215                 return;
1216         }
1217
1218         if ((ppp->flags & SC_MULTILINK) == 0) {
1219                 /* not doing multilink: send it down the first channel */
1220                 list = list->next;
1221                 pch = list_entry(list, struct channel, clist);
1222
1223                 spin_lock_bh(&pch->downl);
1224                 if (pch->chan) {
1225                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1226                                 ppp->xmit_pending = NULL;
1227                 } else {
1228                         /* channel got unregistered */
1229                         kfree_skb(skb);
1230                         ppp->xmit_pending = NULL;
1231                 }
1232                 spin_unlock_bh(&pch->downl);
1233                 return;
1234         }
1235
1236 #ifdef CONFIG_PPP_MULTILINK
1237         /* Multilink: fragment the packet over as many links
1238            as can take the packet at the moment. */
1239         if (!ppp_mp_explode(ppp, skb))
1240                 return;
1241 #endif /* CONFIG_PPP_MULTILINK */
1242
1243         ppp->xmit_pending = NULL;
1244         kfree_skb(skb);
1245 }
1246
1247 #ifdef CONFIG_PPP_MULTILINK
1248 /*
1249  * Divide a packet to be transmitted into fragments and
1250  * send them out the individual links.
1251  */
1252 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1253 {
1254         int len, fragsize;
1255         int i, bits, hdrlen, mtu;
1256         int flen;
1257         int navail, nfree;
1258         int nbigger;
1259         unsigned char *p, *q;
1260         struct list_head *list;
1261         struct channel *pch;
1262         struct sk_buff *frag;
1263         struct ppp_channel *chan;
1264
1265         nfree = 0;      /* # channels which have no packet already queued */
1266         navail = 0;     /* total # of usable channels (not deregistered) */
1267         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1268         i = 0;
1269         list_for_each_entry(pch, &ppp->channels, clist) {
1270                 navail += pch->avail = (pch->chan != NULL);
1271                 if (pch->avail) {
1272                         if (skb_queue_empty(&pch->file.xq) ||
1273                             !pch->had_frag) {
1274                                 pch->avail = 2;
1275                                 ++nfree;
1276                         }
1277                         if (!pch->had_frag && i < ppp->nxchan)
1278                                 ppp->nxchan = i;
1279                 }
1280                 ++i;
1281         }
1282
1283         /*
1284          * Don't start sending this packet unless at least half of
1285          * the channels are free.  This gives much better TCP
1286          * performance if we have a lot of channels.
1287          */
1288         if (nfree == 0 || nfree < navail / 2)
1289                 return 0;       /* can't take now, leave it in xmit_pending */
1290
1291         /* Do protocol field compression (XXX this should be optional) */
1292         p = skb->data;
1293         len = skb->len;
1294         if (*p == 0) {
1295                 ++p;
1296                 --len;
1297         }
1298
1299         /*
1300          * Decide on fragment size.
1301          * We create a fragment for each free channel regardless of
1302          * how small they are (i.e. even 0 length) in order to minimize
1303          * the time that it will take to detect when a channel drops
1304          * a fragment.
1305          */
1306         fragsize = len;
1307         if (nfree > 1)
1308                 fragsize = ROUNDUP(fragsize, nfree);
1309         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1310            except if nbigger==0, then they all get fragsize. */
1311         nbigger = len % nfree;
1312
1313         /* skip to the channel after the one we last used
1314            and start at that one */
1315         list = &ppp->channels;
1316         for (i = 0; i < ppp->nxchan; ++i) {
1317                 list = list->next;
1318                 if (list == &ppp->channels) {
1319                         i = 0;
1320                         break;
1321                 }
1322         }
1323
1324         /* create a fragment for each channel */
1325         bits = B;
1326         while (nfree > 0 || len > 0) {
1327                 list = list->next;
1328                 if (list == &ppp->channels) {
1329                         i = 0;
1330                         continue;
1331                 }
1332                 pch = list_entry(list, struct channel, clist);
1333                 ++i;
1334                 if (!pch->avail)
1335                         continue;
1336
1337                 /*
1338                  * Skip this channel if it has a fragment pending already and
1339                  * we haven't given a fragment to all of the free channels.
1340                  */
1341                 if (pch->avail == 1) {
1342                         if (nfree > 0)
1343                                 continue;
1344                 } else {
1345                         --nfree;
1346                         pch->avail = 1;
1347                 }
1348
1349                 /* check the channel's mtu and whether it is still attached. */
1350                 spin_lock_bh(&pch->downl);
1351                 if (pch->chan == NULL) {
1352                         /* can't use this channel, it's being deregistered */
1353                         spin_unlock_bh(&pch->downl);
1354                         pch->avail = 0;
1355                         if (--navail == 0)
1356                                 break;
1357                         continue;
1358                 }
1359
1360                 /*
1361                  * Create a fragment for this channel of
1362                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1363                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1364                  * MTU, so we use mtu = 2 + hdrlen.
1365                  */
1366                 if (fragsize > len)
1367                         fragsize = len;
1368                 flen = fragsize;
1369                 mtu = pch->chan->mtu + 2 - hdrlen;
1370                 if (mtu < 4)
1371                         mtu = 4;
1372                 if (flen > mtu)
1373                         flen = mtu;
1374                 if (flen == len && nfree == 0)
1375                         bits |= E;
1376                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1377                 if (frag == 0)
1378                         goto noskb;
1379                 q = skb_put(frag, flen + hdrlen);
1380
1381                 /* make the MP header */
1382                 q[0] = PPP_MP >> 8;
1383                 q[1] = PPP_MP;
1384                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1385                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1386                         q[3] = ppp->nxseq;
1387                 } else {
1388                         q[2] = bits;
1389                         q[3] = ppp->nxseq >> 16;
1390                         q[4] = ppp->nxseq >> 8;
1391                         q[5] = ppp->nxseq;
1392                 }
1393
1394                 /*
1395                  * Copy the data in.
1396                  * Unfortunately there is a bug in older versions of
1397                  * the Linux PPP multilink reconstruction code where it
1398                  * drops 0-length fragments.  Therefore we make sure the
1399                  * fragment has at least one byte of data.  Any bytes
1400                  * we add in this situation will end up as padding on the
1401                  * end of the reconstructed packet.
1402                  */
1403                 if (flen == 0)
1404                         *skb_put(frag, 1) = 0;
1405                 else
1406                         memcpy(q + hdrlen, p, flen);
1407
1408                 /* try to send it down the channel */
1409                 chan = pch->chan;
1410                 if (!skb_queue_empty(&pch->file.xq) ||
1411                     !chan->ops->start_xmit(chan, frag))
1412                         skb_queue_tail(&pch->file.xq, frag);
1413                 pch->had_frag = 1;
1414                 p += flen;
1415                 len -= flen;
1416                 ++ppp->nxseq;
1417                 bits = 0;
1418                 spin_unlock_bh(&pch->downl);
1419
1420                 if (--nbigger == 0 && fragsize > 0)
1421                         --fragsize;
1422         }
1423         ppp->nxchan = i;
1424
1425         return 1;
1426
1427  noskb:
1428         spin_unlock_bh(&pch->downl);
1429         if (ppp->debug & 1)
1430                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1431         ++ppp->stats.tx_errors;
1432         ++ppp->nxseq;
1433         return 1;       /* abandon the frame */
1434 }
1435 #endif /* CONFIG_PPP_MULTILINK */
1436
1437 /*
1438  * Try to send data out on a channel.
1439  */
1440 static void
1441 ppp_channel_push(struct channel *pch)
1442 {
1443         struct sk_buff *skb;
1444         struct ppp *ppp;
1445
1446         spin_lock_bh(&pch->downl);
1447         if (pch->chan != 0) {
1448                 while (!skb_queue_empty(&pch->file.xq)) {
1449                         skb = skb_dequeue(&pch->file.xq);
1450                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1451                                 /* put the packet back and try again later */
1452                                 skb_queue_head(&pch->file.xq, skb);
1453                                 break;
1454                         }
1455                 }
1456         } else {
1457                 /* channel got deregistered */
1458                 skb_queue_purge(&pch->file.xq);
1459         }
1460         spin_unlock_bh(&pch->downl);
1461         /* see if there is anything from the attached unit to be sent */
1462         if (skb_queue_empty(&pch->file.xq)) {
1463                 read_lock_bh(&pch->upl);
1464                 ppp = pch->ppp;
1465                 if (ppp != 0)
1466                         ppp_xmit_process(ppp);
1467                 read_unlock_bh(&pch->upl);
1468         }
1469 }
1470
1471 /*
1472  * Receive-side routines.
1473  */
1474
1475 /* misuse a few fields of the skb for MP reconstruction */
1476 #define sequence        priority
1477 #define BEbits          cb[0]
1478
1479 static inline void
1480 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1481 {
1482         ppp_recv_lock(ppp);
1483         /* ppp->dev == 0 means interface is closing down */
1484         if (ppp->dev != 0)
1485                 ppp_receive_frame(ppp, skb, pch);
1486         else
1487                 kfree_skb(skb);
1488         ppp_recv_unlock(ppp);
1489 }
1490
1491 void
1492 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1493 {
1494         struct channel *pch = chan->ppp;
1495         int proto;
1496
1497         if (pch == 0 || skb->len == 0) {
1498                 kfree_skb(skb);
1499                 return;
1500         }
1501
1502         proto = PPP_PROTO(skb);
1503         read_lock_bh(&pch->upl);
1504         if (pch->ppp == 0 || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1505                 /* put it on the channel queue */
1506                 skb_queue_tail(&pch->file.rq, skb);
1507                 /* drop old frames if queue too long */
1508                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1509                        && (skb = skb_dequeue(&pch->file.rq)) != 0)
1510                         kfree_skb(skb);
1511                 wake_up_interruptible(&pch->file.rwait);
1512         } else {
1513                 ppp_do_recv(pch->ppp, skb, pch);
1514         }
1515         read_unlock_bh(&pch->upl);
1516 }
1517
1518 /* Put a 0-length skb in the receive queue as an error indication */
1519 void
1520 ppp_input_error(struct ppp_channel *chan, int code)
1521 {
1522         struct channel *pch = chan->ppp;
1523         struct sk_buff *skb;
1524
1525         if (pch == 0)
1526                 return;
1527
1528         read_lock_bh(&pch->upl);
1529         if (pch->ppp != 0) {
1530                 skb = alloc_skb(0, GFP_ATOMIC);
1531                 if (skb != 0) {
1532                         skb->len = 0;           /* probably unnecessary */
1533                         skb->cb[0] = code;
1534                         ppp_do_recv(pch->ppp, skb, pch);
1535                 }
1536         }
1537         read_unlock_bh(&pch->upl);
1538 }
1539
1540 /*
1541  * We come in here to process a received frame.
1542  * The receive side of the ppp unit is locked.
1543  */
1544 static void
1545 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1546 {
1547         if (skb->len >= 2) {
1548 #ifdef CONFIG_PPP_MULTILINK
1549                 /* XXX do channel-level decompression here */
1550                 if (PPP_PROTO(skb) == PPP_MP)
1551                         ppp_receive_mp_frame(ppp, skb, pch);
1552                 else
1553 #endif /* CONFIG_PPP_MULTILINK */
1554                         ppp_receive_nonmp_frame(ppp, skb);
1555                 return;
1556         }
1557
1558         if (skb->len > 0)
1559                 /* note: a 0-length skb is used as an error indication */
1560                 ++ppp->stats.rx_length_errors;
1561
1562         kfree_skb(skb);
1563         ppp_receive_error(ppp);
1564 }
1565
1566 static void
1567 ppp_receive_error(struct ppp *ppp)
1568 {
1569         ++ppp->stats.rx_errors;
1570         if (ppp->vj != 0)
1571                 slhc_toss(ppp->vj);
1572 }
1573
1574 static void
1575 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1576 {
1577         struct sk_buff *ns;
1578         int proto, len, npi;
1579
1580         /*
1581          * Decompress the frame, if compressed.
1582          * Note that some decompressors need to see uncompressed frames
1583          * that come in as well as compressed frames.
1584          */
1585         if (ppp->rc_state != 0 && (ppp->rstate & SC_DECOMP_RUN)
1586             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1587                 skb = ppp_decompress_frame(ppp, skb);
1588
1589         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1590                 goto err;
1591
1592         proto = PPP_PROTO(skb);
1593         switch (proto) {
1594         case PPP_VJC_COMP:
1595                 /* decompress VJ compressed packets */
1596                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1597                         goto err;
1598
1599                 if (skb_tailroom(skb) < 124) {
1600                         /* copy to a new sk_buff with more tailroom */
1601                         ns = dev_alloc_skb(skb->len + 128);
1602                         if (ns == 0) {
1603                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1604                                 goto err;
1605                         }
1606                         skb_reserve(ns, 2);
1607                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1608                         kfree_skb(skb);
1609                         skb = ns;
1610                 }
1611                 else if (!pskb_may_pull(skb, skb->len))
1612                         goto err;
1613
1614                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1615                 if (len <= 0) {
1616                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1617                         goto err;
1618                 }
1619                 len += 2;
1620                 if (len > skb->len)
1621                         skb_put(skb, len - skb->len);
1622                 else if (len < skb->len)
1623                         skb_trim(skb, len);
1624                 proto = PPP_IP;
1625                 break;
1626
1627         case PPP_VJC_UNCOMP:
1628                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1629                         goto err;
1630
1631                 /* Until we fix the decompressor need to make sure
1632                  * data portion is linear.
1633                  */
1634                 if (!pskb_may_pull(skb, skb->len))
1635                         goto err;
1636
1637                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1638                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1639                         goto err;
1640                 }
1641                 proto = PPP_IP;
1642                 break;
1643
1644         case PPP_CCP:
1645                 ppp_ccp_peek(ppp, skb, 1);
1646                 break;
1647         }
1648
1649         ++ppp->stats.rx_packets;
1650         ppp->stats.rx_bytes += skb->len - 2;
1651
1652         npi = proto_to_npindex(proto);
1653         if (npi < 0) {
1654                 /* control or unknown frame - pass it to pppd */
1655                 skb_queue_tail(&ppp->file.rq, skb);
1656                 /* limit queue length by dropping old frames */
1657                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1658                        && (skb = skb_dequeue(&ppp->file.rq)) != 0)
1659                         kfree_skb(skb);
1660                 /* wake up any process polling or blocking on read */
1661                 wake_up_interruptible(&ppp->file.rwait);
1662
1663         } else {
1664                 /* network protocol frame - give it to the kernel */
1665
1666 #ifdef CONFIG_PPP_FILTER
1667                 /* check if the packet passes the pass and active filters */
1668                 /* the filter instructions are constructed assuming
1669                    a four-byte PPP header on each packet */
1670                 *skb_push(skb, 2) = 0;
1671                 if (ppp->pass_filter
1672                     && sk_run_filter(skb, ppp->pass_filter,
1673                                      ppp->pass_len) == 0) {
1674                         if (ppp->debug & 1)
1675                                 printk(KERN_DEBUG "PPP: inbound frame not passed\n");
1676                         kfree_skb(skb);
1677                         return;
1678                 }
1679                 if (!(ppp->active_filter
1680                       && sk_run_filter(skb, ppp->active_filter,
1681                                        ppp->active_len) == 0))
1682                         ppp->last_recv = jiffies;
1683                 skb_pull(skb, 2);
1684 #else
1685                 ppp->last_recv = jiffies;
1686 #endif /* CONFIG_PPP_FILTER */
1687
1688                 if ((ppp->dev->flags & IFF_UP) == 0
1689                     || ppp->npmode[npi] != NPMODE_PASS) {
1690                         kfree_skb(skb);
1691                 } else {
1692                         skb_pull(skb, 2);       /* chop off protocol */
1693                         skb->dev = ppp->dev;
1694                         skb->protocol = htons(npindex_to_ethertype[npi]);
1695                         skb->mac.raw = skb->data;
1696                         netif_rx(skb);
1697                         ppp->dev->last_rx = jiffies;
1698                 }
1699         }
1700         return;
1701
1702  err:
1703         kfree_skb(skb);
1704         ppp_receive_error(ppp);
1705 }
1706
1707 static struct sk_buff *
1708 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1709 {
1710         int proto = PPP_PROTO(skb);
1711         struct sk_buff *ns;
1712         int len;
1713
1714         /* Until we fix all the decompressor's need to make sure
1715          * data portion is linear.
1716          */
1717         if (!pskb_may_pull(skb, skb->len))
1718                 goto err;
1719
1720         if (proto == PPP_COMP) {
1721                 ns = dev_alloc_skb(ppp->mru + PPP_HDRLEN);
1722                 if (ns == 0) {
1723                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1724                         goto err;
1725                 }
1726                 /* the decompressor still expects the A/C bytes in the hdr */
1727                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1728                                 skb->len + 2, ns->data, ppp->mru + PPP_HDRLEN);
1729                 if (len < 0) {
1730                         /* Pass the compressed frame to pppd as an
1731                            error indication. */
1732                         if (len == DECOMP_FATALERROR)
1733                                 ppp->rstate |= SC_DC_FERROR;
1734                         kfree_skb(ns);
1735                         goto err;
1736                 }
1737
1738                 kfree_skb(skb);
1739                 skb = ns;
1740                 skb_put(skb, len);
1741                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1742
1743         } else {
1744                 /* Uncompressed frame - pass to decompressor so it
1745                    can update its dictionary if necessary. */
1746                 if (ppp->rcomp->incomp)
1747                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1748                                            skb->len + 2);
1749         }
1750
1751         return skb;
1752
1753  err:
1754         ppp->rstate |= SC_DC_ERROR;
1755         ppp_receive_error(ppp);
1756         return skb;
1757 }
1758
1759 #ifdef CONFIG_PPP_MULTILINK
1760 /*
1761  * Receive a multilink frame.
1762  * We put it on the reconstruction queue and then pull off
1763  * as many completed frames as we can.
1764  */
1765 static void
1766 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1767 {
1768         u32 mask, seq;
1769         struct channel *ch;
1770         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1771
1772         if (!pskb_may_pull(skb, mphdrlen) || ppp->mrru == 0)
1773                 goto err;               /* no good, throw it away */
1774
1775         /* Decode sequence number and begin/end bits */
1776         if (ppp->flags & SC_MP_SHORTSEQ) {
1777                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1778                 mask = 0xfff;
1779         } else {
1780                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1781                 mask = 0xffffff;
1782         }
1783         skb->BEbits = skb->data[2];
1784         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1785
1786         /*
1787          * Do protocol ID decompression on the first fragment of each packet.
1788          */
1789         if ((skb->BEbits & B) && (skb->data[0] & 1))
1790                 *skb_push(skb, 1) = 0;
1791
1792         /*
1793          * Expand sequence number to 32 bits, making it as close
1794          * as possible to ppp->minseq.
1795          */
1796         seq |= ppp->minseq & ~mask;
1797         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1798                 seq += mask + 1;
1799         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1800                 seq -= mask + 1;        /* should never happen */
1801         skb->sequence = seq;
1802         pch->lastseq = seq;
1803
1804         /*
1805          * If this packet comes before the next one we were expecting,
1806          * drop it.
1807          */
1808         if (seq_before(seq, ppp->nextseq)) {
1809                 kfree_skb(skb);
1810                 ++ppp->stats.rx_dropped;
1811                 ppp_receive_error(ppp);
1812                 return;
1813         }
1814
1815         /*
1816          * Reevaluate minseq, the minimum over all channels of the
1817          * last sequence number received on each channel.  Because of
1818          * the increasing sequence number rule, we know that any fragment
1819          * before `minseq' which hasn't arrived is never going to arrive.
1820          * The list of channels can't change because we have the receive
1821          * side of the ppp unit locked.
1822          */
1823         list_for_each_entry(ch, &ppp->channels, clist) {
1824                 if (seq_before(ch->lastseq, seq))
1825                         seq = ch->lastseq;
1826         }
1827         if (seq_before(ppp->minseq, seq))
1828                 ppp->minseq = seq;
1829
1830         /* Put the fragment on the reconstruction queue */
1831         ppp_mp_insert(ppp, skb);
1832
1833         /* If the queue is getting long, don't wait any longer for packets
1834            before the start of the queue. */
1835         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN
1836             && seq_before(ppp->minseq, ppp->mrq.next->sequence))
1837                 ppp->minseq = ppp->mrq.next->sequence;
1838
1839         /* Pull completed packets off the queue and receive them. */
1840         while ((skb = ppp_mp_reconstruct(ppp)) != 0)
1841                 ppp_receive_nonmp_frame(ppp, skb);
1842
1843         return;
1844
1845  err:
1846         kfree_skb(skb);
1847         ppp_receive_error(ppp);
1848 }
1849
1850 /*
1851  * Insert a fragment on the MP reconstruction queue.
1852  * The queue is ordered by increasing sequence number.
1853  */
1854 static void
1855 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1856 {
1857         struct sk_buff *p;
1858         struct sk_buff_head *list = &ppp->mrq;
1859         u32 seq = skb->sequence;
1860
1861         /* N.B. we don't need to lock the list lock because we have the
1862            ppp unit receive-side lock. */
1863         for (p = list->next; p != (struct sk_buff *)list; p = p->next)
1864                 if (seq_before(seq, p->sequence))
1865                         break;
1866         __skb_insert(skb, p->prev, p, list);
1867 }
1868
1869 /*
1870  * Reconstruct a packet from the MP fragment queue.
1871  * We go through increasing sequence numbers until we find a
1872  * complete packet, or we get to the sequence number for a fragment
1873  * which hasn't arrived but might still do so.
1874  */
1875 struct sk_buff *
1876 ppp_mp_reconstruct(struct ppp *ppp)
1877 {
1878         u32 seq = ppp->nextseq;
1879         u32 minseq = ppp->minseq;
1880         struct sk_buff_head *list = &ppp->mrq;
1881         struct sk_buff *p, *next;
1882         struct sk_buff *head, *tail;
1883         struct sk_buff *skb = NULL;
1884         int lost = 0, len = 0;
1885
1886         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1887                 return NULL;
1888         head = list->next;
1889         tail = NULL;
1890         for (p = head; p != (struct sk_buff *) list; p = next) {
1891                 next = p->next;
1892                 if (seq_before(p->sequence, seq)) {
1893                         /* this can't happen, anyway ignore the skb */
1894                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1895                                p->sequence, seq);
1896                         head = next;
1897                         continue;
1898                 }
1899                 if (p->sequence != seq) {
1900                         /* Fragment `seq' is missing.  If it is after
1901                            minseq, it might arrive later, so stop here. */
1902                         if (seq_after(seq, minseq))
1903                                 break;
1904                         /* Fragment `seq' is lost, keep going. */
1905                         lost = 1;
1906                         seq = seq_before(minseq, p->sequence)?
1907                                 minseq + 1: p->sequence;
1908                         next = p;
1909                         continue;
1910                 }
1911
1912                 /*
1913                  * At this point we know that all the fragments from
1914                  * ppp->nextseq to seq are either present or lost.
1915                  * Also, there are no complete packets in the queue
1916                  * that have no missing fragments and end before this
1917                  * fragment.
1918                  */
1919
1920                 /* B bit set indicates this fragment starts a packet */
1921                 if (p->BEbits & B) {
1922                         head = p;
1923                         lost = 0;
1924                         len = 0;
1925                 }
1926
1927                 len += p->len;
1928
1929                 /* Got a complete packet yet? */
1930                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1931                         if (len > ppp->mrru + 2) {
1932                                 ++ppp->stats.rx_length_errors;
1933                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1934                                        " is too long (%d)\n", len);
1935                         } else if (p == head) {
1936                                 /* fragment is complete packet - reuse skb */
1937                                 tail = p;
1938                                 skb = skb_get(p);
1939                                 break;
1940                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1941                                 ++ppp->stats.rx_missed_errors;
1942                                 printk(KERN_DEBUG "PPP: no memory for "
1943                                        "reconstructed packet");
1944                         } else {
1945                                 tail = p;
1946                                 break;
1947                         }
1948                         ppp->nextseq = seq + 1;
1949                 }
1950
1951                 /*
1952                  * If this is the ending fragment of a packet,
1953                  * and we haven't found a complete valid packet yet,
1954                  * we can discard up to and including this fragment.
1955                  */
1956                 if (p->BEbits & E)
1957                         head = next;
1958
1959                 ++seq;
1960         }
1961
1962         /* If we have a complete packet, copy it all into one skb. */
1963         if (tail != NULL) {
1964                 /* If we have discarded any fragments,
1965                    signal a receive error. */
1966                 if (head->sequence != ppp->nextseq) {
1967                         if (ppp->debug & 1)
1968                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1969                                        ppp->nextseq, head->sequence-1);
1970                         ++ppp->stats.rx_dropped;
1971                         ppp_receive_error(ppp);
1972                 }
1973
1974                 if (head != tail)
1975                         /* copy to a single skb */
1976                         for (p = head; p != tail->next; p = p->next)
1977                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1978                 ppp->nextseq = tail->sequence + 1;
1979                 head = tail->next;
1980         }
1981
1982         /* Discard all the skbuffs that we have copied the data out of
1983            or that we can't use. */
1984         while ((p = list->next) != head) {
1985                 __skb_unlink(p, list);
1986                 kfree_skb(p);
1987         }
1988
1989         return skb;
1990 }
1991 #endif /* CONFIG_PPP_MULTILINK */
1992
1993 /*
1994  * Channel interface.
1995  */
1996
1997 /*
1998  * Create a new, unattached ppp channel.
1999  */
2000 int
2001 ppp_register_channel(struct ppp_channel *chan)
2002 {
2003         struct channel *pch;
2004
2005         pch = kmalloc(sizeof(struct channel), GFP_KERNEL);
2006         if (pch == 0)
2007                 return -ENOMEM;
2008         memset(pch, 0, sizeof(struct channel));
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 = kmalloc(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         memset(ppp, 0, sizeof(struct ppp));
2425
2426         ppp->mru = PPP_MRU;
2427         init_ppp_file(&ppp->file, INTERFACE);
2428         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2429         for (i = 0; i < NUM_NP; ++i)
2430                 ppp->npmode[i] = NPMODE_PASS;
2431         INIT_LIST_HEAD(&ppp->channels);
2432         spin_lock_init(&ppp->rlock);
2433         spin_lock_init(&ppp->wlock);
2434 #ifdef CONFIG_PPP_MULTILINK
2435         ppp->minseq = -1;
2436         skb_queue_head_init(&ppp->mrq);
2437 #endif /* CONFIG_PPP_MULTILINK */
2438         ppp->dev = dev;
2439         dev->priv = ppp;
2440
2441         dev->hard_start_xmit = ppp_start_xmit;
2442         dev->get_stats = ppp_net_stats;
2443         dev->do_ioctl = ppp_net_ioctl;
2444
2445         ret = -EEXIST;
2446         down(&all_ppp_sem);
2447         if (unit < 0)
2448                 unit = cardmap_find_first_free(all_ppp_units);
2449         else if (cardmap_get(all_ppp_units, unit) != NULL)
2450                 goto out2;      /* unit already exists */
2451
2452         /* Initialize the new ppp unit */
2453         ppp->file.index = unit;
2454         sprintf(dev->name, "ppp%d", unit);
2455
2456         ret = register_netdev(dev);
2457         if (ret != 0) {
2458                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2459                        dev->name, ret);
2460                 goto out2;
2461         }
2462
2463         atomic_inc(&ppp_unit_count);
2464         cardmap_set(&all_ppp_units, unit, ppp);
2465         up(&all_ppp_sem);
2466         *retp = 0;
2467         return ppp;
2468
2469 out2:
2470         up(&all_ppp_sem);
2471         free_netdev(dev);
2472 out1:
2473         kfree(ppp);
2474 out:
2475         *retp = ret;
2476         return NULL;
2477 }
2478
2479 /*
2480  * Initialize a ppp_file structure.
2481  */
2482 static void
2483 init_ppp_file(struct ppp_file *pf, int kind)
2484 {
2485         pf->kind = kind;
2486         skb_queue_head_init(&pf->xq);
2487         skb_queue_head_init(&pf->rq);
2488         atomic_set(&pf->refcnt, 1);
2489         init_waitqueue_head(&pf->rwait);
2490 }
2491
2492 /*
2493  * Take down a ppp interface unit - called when the owning file
2494  * (the one that created the unit) is closed or detached.
2495  */
2496 static void ppp_shutdown_interface(struct ppp *ppp)
2497 {
2498         struct net_device *dev;
2499
2500         down(&all_ppp_sem);
2501         ppp_lock(ppp);
2502         dev = ppp->dev;
2503         ppp->dev = NULL;
2504         ppp_unlock(ppp);
2505         /* This will call dev_close() for us. */
2506         if (dev) {
2507                 unregister_netdev(dev);
2508                 free_netdev(dev);
2509         }
2510         cardmap_set(&all_ppp_units, ppp->file.index, NULL);
2511         ppp->file.dead = 1;
2512         ppp->owner = NULL;
2513         wake_up_interruptible(&ppp->file.rwait);
2514         up(&all_ppp_sem);
2515 }
2516
2517 /*
2518  * Free the memory used by a ppp unit.  This is only called once
2519  * there are no channels connected to the unit and no file structs
2520  * that reference the unit.
2521  */
2522 static void ppp_destroy_interface(struct ppp *ppp)
2523 {
2524         atomic_dec(&ppp_unit_count);
2525
2526         if (!ppp->file.dead || ppp->n_channels) {
2527                 /* "can't happen" */
2528                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2529                        "n_channels=%d !\n", ppp, ppp->file.dead,
2530                        ppp->n_channels);
2531                 return;
2532         }
2533
2534         ppp_ccp_closed(ppp);
2535         if (ppp->vj) {
2536                 slhc_free(ppp->vj);
2537                 ppp->vj = NULL;
2538         }
2539         skb_queue_purge(&ppp->file.xq);
2540         skb_queue_purge(&ppp->file.rq);
2541 #ifdef CONFIG_PPP_MULTILINK
2542         skb_queue_purge(&ppp->mrq);
2543 #endif /* CONFIG_PPP_MULTILINK */
2544 #ifdef CONFIG_PPP_FILTER
2545         kfree(ppp->pass_filter);
2546         ppp->pass_filter = NULL;
2547         kfree(ppp->active_filter);
2548         ppp->active_filter = NULL;
2549 #endif /* CONFIG_PPP_FILTER */
2550
2551         kfree(ppp);
2552 }
2553
2554 /*
2555  * Locate an existing ppp unit.
2556  * The caller should have locked the all_ppp_sem.
2557  */
2558 static struct ppp *
2559 ppp_find_unit(int unit)
2560 {
2561         return cardmap_get(all_ppp_units, unit);
2562 }
2563
2564 /*
2565  * Locate an existing ppp channel.
2566  * The caller should have locked the all_channels_lock.
2567  * First we look in the new_channels list, then in the
2568  * all_channels list.  If found in the new_channels list,
2569  * we move it to the all_channels list.  This is for speed
2570  * when we have a lot of channels in use.
2571  */
2572 static struct channel *
2573 ppp_find_channel(int unit)
2574 {
2575         struct channel *pch;
2576
2577         list_for_each_entry(pch, &new_channels, list) {
2578                 if (pch->file.index == unit) {
2579                         list_del(&pch->list);
2580                         list_add(&pch->list, &all_channels);
2581                         return pch;
2582                 }
2583         }
2584         list_for_each_entry(pch, &all_channels, list) {
2585                 if (pch->file.index == unit)
2586                         return pch;
2587         }
2588         return NULL;
2589 }
2590
2591 /*
2592  * Connect a PPP channel to a PPP interface unit.
2593  */
2594 static int
2595 ppp_connect_channel(struct channel *pch, int unit)
2596 {
2597         struct ppp *ppp;
2598         int ret = -ENXIO;
2599         int hdrlen;
2600
2601         down(&all_ppp_sem);
2602         ppp = ppp_find_unit(unit);
2603         if (ppp == 0)
2604                 goto out;
2605         write_lock_bh(&pch->upl);
2606         ret = -EINVAL;
2607         if (pch->ppp != 0)
2608                 goto outl;
2609
2610         ppp_lock(ppp);
2611         if (pch->file.hdrlen > ppp->file.hdrlen)
2612                 ppp->file.hdrlen = pch->file.hdrlen;
2613         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2614         if (ppp->dev && hdrlen > ppp->dev->hard_header_len)
2615                 ppp->dev->hard_header_len = hdrlen;
2616         list_add_tail(&pch->clist, &ppp->channels);
2617         ++ppp->n_channels;
2618         pch->ppp = ppp;
2619         atomic_inc(&ppp->file.refcnt);
2620         ppp_unlock(ppp);
2621         ret = 0;
2622
2623  outl:
2624         write_unlock_bh(&pch->upl);
2625  out:
2626         up(&all_ppp_sem);
2627         return ret;
2628 }
2629
2630 /*
2631  * Disconnect a channel from its ppp unit.
2632  */
2633 static int
2634 ppp_disconnect_channel(struct channel *pch)
2635 {
2636         struct ppp *ppp;
2637         int err = -EINVAL;
2638
2639         write_lock_bh(&pch->upl);
2640         ppp = pch->ppp;
2641         pch->ppp = NULL;
2642         write_unlock_bh(&pch->upl);
2643         if (ppp != 0) {
2644                 /* remove it from the ppp unit's list */
2645                 ppp_lock(ppp);
2646                 list_del(&pch->clist);
2647                 if (--ppp->n_channels == 0)
2648                         wake_up_interruptible(&ppp->file.rwait);
2649                 ppp_unlock(ppp);
2650                 if (atomic_dec_and_test(&ppp->file.refcnt))
2651                         ppp_destroy_interface(ppp);
2652                 err = 0;
2653         }
2654         return err;
2655 }
2656
2657 /*
2658  * Free up the resources used by a ppp channel.
2659  */
2660 static void ppp_destroy_channel(struct channel *pch)
2661 {
2662         atomic_dec(&channel_count);
2663
2664         if (!pch->file.dead) {
2665                 /* "can't happen" */
2666                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2667                        pch);
2668                 return;
2669         }
2670         skb_queue_purge(&pch->file.xq);
2671         skb_queue_purge(&pch->file.rq);
2672         kfree(pch);
2673 }
2674
2675 static void __exit ppp_cleanup(void)
2676 {
2677         /* should never happen */
2678         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2679                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2680         cardmap_destroy(&all_ppp_units);
2681         if (unregister_chrdev(PPP_MAJOR, "ppp") != 0)
2682                 printk(KERN_ERR "PPP: failed to unregister PPP device\n");
2683         devfs_remove("ppp");
2684         class_device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2685         class_destroy(ppp_class);
2686 }
2687
2688 /*
2689  * Cardmap implementation.
2690  */
2691 static void *cardmap_get(struct cardmap *map, unsigned int nr)
2692 {
2693         struct cardmap *p;
2694         int i;
2695
2696         for (p = map; p != NULL; ) {
2697                 if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
2698                         return NULL;
2699                 if (p->shift == 0)
2700                         return p->ptr[i];
2701                 nr &= ~(CARDMAP_MASK << p->shift);
2702                 p = p->ptr[i];
2703         }
2704         return NULL;
2705 }
2706
2707 static void cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
2708 {
2709         struct cardmap *p;
2710         int i;
2711
2712         p = *pmap;
2713         if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
2714                 do {
2715                         /* need a new top level */
2716                         struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
2717                         memset(np, 0, sizeof(*np));
2718                         np->ptr[0] = p;
2719                         if (p != NULL) {
2720                                 np->shift = p->shift + CARDMAP_ORDER;
2721                                 p->parent = np;
2722                         } else
2723                                 np->shift = 0;
2724                         p = np;
2725                 } while ((nr >> p->shift) >= CARDMAP_WIDTH);
2726                 *pmap = p;
2727         }
2728         while (p->shift > 0) {
2729                 i = (nr >> p->shift) & CARDMAP_MASK;
2730                 if (p->ptr[i] == NULL) {
2731                         struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
2732                         memset(np, 0, sizeof(*np));
2733                         np->shift = p->shift - CARDMAP_ORDER;
2734                         np->parent = p;
2735                         p->ptr[i] = np;
2736                 }
2737                 if (ptr == NULL)
2738                         clear_bit(i, &p->inuse);
2739                 p = p->ptr[i];
2740         }
2741         i = nr & CARDMAP_MASK;
2742         p->ptr[i] = ptr;
2743         if (ptr != NULL)
2744                 set_bit(i, &p->inuse);
2745         else
2746                 clear_bit(i, &p->inuse);
2747 }
2748
2749 static unsigned int cardmap_find_first_free(struct cardmap *map)
2750 {
2751         struct cardmap *p;
2752         unsigned int nr = 0;
2753         int i;
2754
2755         if ((p = map) == NULL)
2756                 return 0;
2757         for (;;) {
2758                 i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
2759                 if (i >= CARDMAP_WIDTH) {
2760                         if (p->parent == NULL)
2761                                 return CARDMAP_WIDTH << p->shift;
2762                         p = p->parent;
2763                         i = (nr >> p->shift) & CARDMAP_MASK;
2764                         set_bit(i, &p->inuse);
2765                         continue;
2766                 }
2767                 nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
2768                 if (p->shift == 0 || p->ptr[i] == NULL)
2769                         return nr;
2770                 p = p->ptr[i];
2771         }
2772 }
2773
2774 static void cardmap_destroy(struct cardmap **pmap)
2775 {
2776         struct cardmap *p, *np;
2777         int i;
2778
2779         for (p = *pmap; p != NULL; p = np) {
2780                 if (p->shift != 0) {
2781                         for (i = 0; i < CARDMAP_WIDTH; ++i)
2782                                 if (p->ptr[i] != NULL)
2783                                         break;
2784                         if (i < CARDMAP_WIDTH) {
2785                                 np = p->ptr[i];
2786                                 p->ptr[i] = NULL;
2787                                 continue;
2788                         }
2789                 }
2790                 np = p->parent;
2791                 kfree(p);
2792         }
2793         *pmap = NULL;
2794 }
2795
2796 /* Module/initialization stuff */
2797
2798 module_init(ppp_init);
2799 module_exit(ppp_cleanup);
2800
2801 EXPORT_SYMBOL(ppp_register_channel);
2802 EXPORT_SYMBOL(ppp_unregister_channel);
2803 EXPORT_SYMBOL(ppp_channel_index);
2804 EXPORT_SYMBOL(ppp_unit_number);
2805 EXPORT_SYMBOL(ppp_input);
2806 EXPORT_SYMBOL(ppp_input_error);
2807 EXPORT_SYMBOL(ppp_output_wakeup);
2808 EXPORT_SYMBOL(ppp_register_compressor);
2809 EXPORT_SYMBOL(ppp_unregister_compressor);
2810 MODULE_LICENSE("GPL");
2811 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2812 MODULE_ALIAS("/dev/ppp");