drivers/net/ppp_generic.c

   1 /*
   2  * Generic PPP layer for Linux.
   3  *
   4  * Copyright 1999-2002 Paul Mackerras.
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  *
  11  * The generic PPP layer handles the PPP network interfaces, the
  12  * /dev/ppp device, packet and VJ compression, and multilink.
  13  * It talks to PPP `channels' via the interface defined in
  14  * include/linux/ppp_channel.h.  Channels provide the basic means for
  15  * sending and receiving PPP frames on some kind of communications
  16  * channel.
  17  *
  18  * Part of the code in this driver was inspired by the old async-only
  19  * PPP driver, written by Michael Callahan and Al Longyear, and
  20  * subsequently hacked by Paul Mackerras.
  21  *
  22  * ==FILEVERSION 20041108==
  23  */
  24
  25 #include <linux/module.h>
  26 #include <linux/kernel.h>
  27 #include <linux/kmod.h>
  28 #include <linux/init.h>
  29 #include <linux/list.h>
  30 #include <linux/idr.h>
  31 #include <linux/netdevice.h>
  32 #include <linux/poll.h>
  33 #include <linux/ppp_defs.h>
  34 #include <linux/filter.h>
  35 #include <linux/if_ppp.h>
  36 #include <linux/ppp_channel.h>
  37 #include <linux/ppp-comp.h>
  38 #include <linux/skbuff.h>
  39 #include <linux/rtnetlink.h>
  40 #include <linux/if_arp.h>
  41 #include <linux/ip.h>
  42 #include <linux/tcp.h>
  43 #include <linux/smp_lock.h>
  44 #include <linux/spinlock.h>
  45 #include <linux/rwsem.h>
  46 #include <linux/stddef.h>
  47 #include <linux/device.h>
  48 #include <linux/mutex.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)          container_of(pf, 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 /*
  93  * Data structure describing one ppp unit.
  94  * A ppp unit corresponds to a ppp network interface device
  95  * and represents a multilink bundle.
  96  * It can have 0 or more ppp channels connected to it.
  97  */
  98 struct ppp {
  99         struct ppp_file file;           /* stuff for read/write/poll 0 */
 100         struct file     *owner;         /* file that owns this unit 48 */
 101         struct list_head channels;      /* list of attached channels 4c */
 102         int             n_channels;     /* how many channels are attached 54 */
 103         spinlock_t      rlock;          /* lock for receive side 58 */
 104         spinlock_t      wlock;          /* lock for transmit side 5c */
 105         int             mru;            /* max receive unit 60 */
 106         unsigned int    flags;          /* control bits 64 */
 107         unsigned int    xstate;         /* transmit state bits 68 */
 108         unsigned int    rstate;         /* receive state bits 6c */
 109         int             debug;          /* debug flags 70 */
 110         struct slcompress *vj;          /* state for VJ header compression */
 111         enum NPmode     npmode[NUM_NP]; /* what to do with each net proto 78 */
 112         struct sk_buff  *xmit_pending;  /* a packet ready to go out 88 */
 113         struct compressor *xcomp;       /* transmit packet compressor 8c */
 114         void            *xc_state;      /* its internal state 90 */
 115         struct compressor *rcomp;       /* receive decompressor 94 */
 116         void            *rc_state;      /* its internal state 98 */
 117         unsigned long   last_xmit;      /* jiffies when last pkt sent 9c */
 118         unsigned long   last_recv;      /* jiffies when last pkt rcvd a0 */
 119         struct net_device *dev;         /* network interface device a4 */
 120         int             closing;        /* is device closing down? a8 */
 121 #ifdef CONFIG_PPP_MULTILINK
 122         int             nxchan;         /* next channel to send something on */
 123         u32             nxseq;          /* next sequence number to send */
 124         int             mrru;           /* MP: max reconst. receive unit */
 125         u32             nextseq;        /* MP: seq no of next packet */
 126         u32             minseq;         /* MP: min of most recent seqnos */
 127         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
 128 #endif /* CONFIG_PPP_MULTILINK */
 129 #ifdef CONFIG_PPP_FILTER
 130         struct sock_filter *pass_filter;        /* filter for packets to pass */
 131         struct sock_filter *active_filter;/* filter for pkts to reset idle */
 132         unsigned pass_len, active_len;
 133 #endif /* CONFIG_PPP_FILTER */
 134 };
 135
 136 /*
 137  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
 138  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
 139  * SC_MUST_COMP
 140  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
 141  * Bits in xstate: SC_COMP_RUN
 142  */
 143 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
 144                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
 145                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
 146
 147 /*
 148  * Private data structure for each channel.
 149  * This includes the data structure used for multilink.
 150  */
 151 struct channel {
 152         struct ppp_file file;           /* stuff for read/write/poll */
 153         struct list_head list;          /* link in all/new_channels list */
 154         struct ppp_channel *chan;       /* public channel data structure */
 155         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
 156         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
 157         struct ppp      *ppp;           /* ppp unit we're connected to */
 158         struct list_head clist;         /* link in list of channels per unit */
 159         rwlock_t        upl;            /* protects `ppp' */
 160 #ifdef CONFIG_PPP_MULTILINK
 161         u8              avail;          /* flag used in multilink stuff */
 162         u8              had_frag;       /* >= 1 fragments have been sent */
 163         u32             lastseq;        /* MP: last sequence # received */
 164 #endif /* CONFIG_PPP_MULTILINK */
 165 };
 166
 167 /*
 168  * SMP locking issues:
 169  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
 170  * list and the ppp.n_channels field, you need to take both locks
 171  * before you modify them.
 172  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
 173  * channel.downl.
 174  */
 175
 176 /*
 177  * all_ppp_mutex protects the all_ppp_units mapping.
 178  * It also ensures that finding a ppp unit in the all_ppp_units map
 179  * and updating its file.refcnt field is atomic.
 180  */
 181 static DEFINE_MUTEX(all_ppp_mutex);
 182 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 183 static DEFINE_IDR(ppp_units_idr);
 184
 185 /*
 186  * all_channels_lock protects all_channels and last_channel_index,
 187  * and the atomicity of find a channel and updating its file.refcnt
 188  * field.
 189  */
 190 static DEFINE_SPINLOCK(all_channels_lock);
 191 static LIST_HEAD(all_channels);
 192 static LIST_HEAD(new_channels);
 193 static int last_channel_index;
 194 static atomic_t channel_count = ATOMIC_INIT(0);
 195
 196 /* Get the PPP protocol number from a skb */
 197 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
 198
 199 /* We limit the length of ppp->file.rq to this (arbitrary) value */
 200 #define PPP_MAX_RQLEN   32
 201
 202 /*
 203  * Maximum number of multilink fragments queued up.
 204  * This has to be large enough to cope with the maximum latency of
 205  * the slowest channel relative to the others.  Strictly it should
 206  * depend on the number of channels and their characteristics.
 207  */
 208 #define PPP_MP_MAX_QLEN 128
 209
 210 /* Multilink header bits. */
 211 #define B       0x80            /* this fragment begins a packet */
 212 #define E       0x40            /* this fragment ends a packet */
 213
 214 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
 215 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
 216 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
 217
 218 /* Prototypes. */
 219 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 220                                 unsigned int cmd, unsigned long arg);
 221 static void ppp_xmit_process(struct ppp *ppp);
 222 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
 223 static void ppp_push(struct ppp *ppp);
 224 static void ppp_channel_push(struct channel *pch);
 225 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
 226                               struct channel *pch);
 227 static void ppp_receive_error(struct ppp *ppp);
 228 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
 229 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
 230                                             struct sk_buff *skb);
 231 #ifdef CONFIG_PPP_MULTILINK
 232 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
 233                                 struct channel *pch);
 234 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
 235 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
 236 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
 237 #endif /* CONFIG_PPP_MULTILINK */
 238 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
 239 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
 240 static void ppp_ccp_closed(struct ppp *ppp);
 241 static struct compressor *find_compressor(int type);
 242 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
 243 static struct ppp *ppp_create_interface(int unit, int *retp);
 244 static void init_ppp_file(struct ppp_file *pf, int kind);
 245 static void ppp_shutdown_interface(struct ppp *ppp);
 246 static void ppp_destroy_interface(struct ppp *ppp);
 247 static struct ppp *ppp_find_unit(int unit);
 248 static struct channel *ppp_find_channel(int unit);
 249 static int ppp_connect_channel(struct channel *pch, int unit);
 250 static int ppp_disconnect_channel(struct channel *pch);
 251 static void ppp_destroy_channel(struct channel *pch);
 252 static int unit_get(struct idr *p, void *ptr);
 253 static int unit_set(struct idr *p, void *ptr, int n);
 254 static void unit_put(struct idr *p, int n);
 255 static void *unit_find(struct idr *p, int n);
 256
 257 static struct class *ppp_class;
 258
 259 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
 260 static inline int proto_to_npindex(int proto)
 261 {
 262         switch (proto) {
 263         case PPP_IP:
 264                 return NP_IP;
 265         case PPP_IPV6:
 266                 return NP_IPV6;
 267         case PPP_IPX:
 268                 return NP_IPX;
 269         case PPP_AT:
 270                 return NP_AT;
 271         case PPP_MPLS_UC:
 272                 return NP_MPLS_UC;
 273         case PPP_MPLS_MC:
 274                 return NP_MPLS_MC;
 275         }
 276         return -EINVAL;
 277 }
 278
 279 /* Translates an NP index into a PPP protocol number */
 280 static const int npindex_to_proto[NUM_NP] = {
 281         PPP_IP,
 282         PPP_IPV6,
 283         PPP_IPX,
 284         PPP_AT,
 285         PPP_MPLS_UC,
 286         PPP_MPLS_MC,
 287 };
 288
 289 /* Translates an ethertype into an NP index */
 290 static inline int ethertype_to_npindex(int ethertype)
 291 {
 292         switch (ethertype) {
 293         case ETH_P_IP:
 294                 return NP_IP;
 295         case ETH_P_IPV6:
 296                 return NP_IPV6;
 297         case ETH_P_IPX:
 298                 return NP_IPX;
 299         case ETH_P_PPPTALK:
 300         case ETH_P_ATALK:
 301                 return NP_AT;
 302         case ETH_P_MPLS_UC:
 303                 return NP_MPLS_UC;
 304         case ETH_P_MPLS_MC:
 305                 return NP_MPLS_MC;
 306         }
 307         return -1;
 308 }
 309
 310 /* Translates an NP index into an ethertype */
 311 static const int npindex_to_ethertype[NUM_NP] = {
 312         ETH_P_IP,
 313         ETH_P_IPV6,
 314         ETH_P_IPX,
 315         ETH_P_PPPTALK,
 316         ETH_P_MPLS_UC,
 317         ETH_P_MPLS_MC,
 318 };
 319
 320 /*
 321  * Locking shorthand.
 322  */
 323 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
 324 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
 325 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
 326 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
 327 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
 328                                      ppp_recv_lock(ppp); } while (0)
 329 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
 330                                      ppp_xmit_unlock(ppp); } while (0)
 331
 332 /*
 333  * /dev/ppp device routines.
 334  * The /dev/ppp device is used by pppd to control the ppp unit.
 335  * It supports the read, write, ioctl and poll functions.
 336  * Open instances of /dev/ppp can be in one of three states:
 337  * unattached, attached to a ppp unit, or attached to a ppp channel.
 338  */
 339 static int ppp_open(struct inode *inode, struct file *file)
 340 {
 341         cycle_kernel_lock();
 342         /*
 343          * This could (should?) be enforced by the permissions on /dev/ppp.
 344          */
 345         if (!capable(CAP_NET_ADMIN))
 346                 return -EPERM;
 347         return 0;
 348 }
 349
 350 static int ppp_release(struct inode *unused, struct file *file)
 351 {
 352         struct ppp_file *pf = file->private_data;
 353         struct ppp *ppp;
 354
 355         if (pf) {
 356                 file->private_data = NULL;
 357                 if (pf->kind == INTERFACE) {
 358                         ppp = PF_TO_PPP(pf);
 359                         if (file == ppp->owner)
 360                                 ppp_shutdown_interface(ppp);
 361                 }
 362                 if (atomic_dec_and_test(&pf->refcnt)) {
 363                         switch (pf->kind) {
 364                         case INTERFACE:
 365                                 ppp_destroy_interface(PF_TO_PPP(pf));
 366                                 break;
 367                         case CHANNEL:
 368                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
 369                                 break;
 370                         }
 371                 }
 372         }
 373         return 0;
 374 }
 375
 376 static ssize_t ppp_read(struct file *file, char __user *buf,
 377                         size_t count, loff_t *ppos)
 378 {
 379         struct ppp_file *pf = file->private_data;
 380         DECLARE_WAITQUEUE(wait, current);
 381         ssize_t ret;
 382         struct sk_buff *skb = NULL;
 383
 384         ret = count;
 385
 386         if (!pf)
 387                 return -ENXIO;
 388         add_wait_queue(&pf->rwait, &wait);
 389         for (;;) {
 390                 set_current_state(TASK_INTERRUPTIBLE);
 391                 skb = skb_dequeue(&pf->rq);
 392                 if (skb)
 393                         break;
 394                 ret = 0;
 395                 if (pf->dead)
 396                         break;
 397                 if (pf->kind == INTERFACE) {
 398                         /*
 399                          * Return 0 (EOF) on an interface that has no
 400                          * channels connected, unless it is looping
 401                          * network traffic (demand mode).
 402                          */
 403                         struct ppp *ppp = PF_TO_PPP(pf);
 404                         if (ppp->n_channels == 0
 405                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 406                                 break;
 407                 }
 408                 ret = -EAGAIN;
 409                 if (file->f_flags & O_NONBLOCK)
 410                         break;
 411                 ret = -ERESTARTSYS;
 412                 if (signal_pending(current))
 413                         break;
 414                 schedule();
 415         }
 416         set_current_state(TASK_RUNNING);
 417         remove_wait_queue(&pf->rwait, &wait);
 418
 419         if (!skb)
 420                 goto out;
 421
 422         ret = -EOVERFLOW;
 423         if (skb->len > count)
 424                 goto outf;
 425         ret = -EFAULT;
 426         if (copy_to_user(buf, skb->data, skb->len))
 427                 goto outf;
 428         ret = skb->len;
 429
 430  outf:
 431         kfree_skb(skb);
 432  out:
 433         return ret;
 434 }
 435
 436 static ssize_t ppp_write(struct file *file, const char __user *buf,
 437                          size_t count, loff_t *ppos)
 438 {
 439         struct ppp_file *pf = file->private_data;
 440         struct sk_buff *skb;
 441         ssize_t ret;
 442
 443         if (!pf)
 444                 return -ENXIO;
 445         ret = -ENOMEM;
 446         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
 447         if (!skb)
 448                 goto out;
 449         skb_reserve(skb, pf->hdrlen);
 450         ret = -EFAULT;
 451         if (copy_from_user(skb_put(skb, count), buf, count)) {
 452                 kfree_skb(skb);
 453                 goto out;
 454         }
 455
 456         skb_queue_tail(&pf->xq, skb);
 457
 458         switch (pf->kind) {
 459         case INTERFACE:
 460                 ppp_xmit_process(PF_TO_PPP(pf));
 461                 break;
 462         case CHANNEL:
 463                 ppp_channel_push(PF_TO_CHANNEL(pf));
 464                 break;
 465         }
 466
 467         ret = count;
 468
 469  out:
 470         return ret;
 471 }
 472
 473 /* No kernel lock - fine */
 474 static unsigned int ppp_poll(struct file *file, poll_table *wait)
 475 {
 476         struct ppp_file *pf = file->private_data;
 477         unsigned int mask;
 478
 479         if (!pf)
 480                 return 0;
 481         poll_wait(file, &pf->rwait, wait);
 482         mask = POLLOUT | POLLWRNORM;
 483         if (skb_peek(&pf->rq))
 484                 mask |= POLLIN | POLLRDNORM;
 485         if (pf->dead)
 486                 mask |= POLLHUP;
 487         else if (pf->kind == INTERFACE) {
 488                 /* see comment in ppp_read */
 489                 struct ppp *ppp = PF_TO_PPP(pf);
 490                 if (ppp->n_channels == 0
 491                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
 492                         mask |= POLLIN | POLLRDNORM;
 493         }
 494
 495         return mask;
 496 }
 497
 498 #ifdef CONFIG_PPP_FILTER
 499 static int get_filter(void __user *arg, struct sock_filter **p)
 500 {
 501         struct sock_fprog uprog;
 502         struct sock_filter *code = NULL;
 503         int len, err;
 504
 505         if (copy_from_user(&uprog, arg, sizeof(uprog)))
 506                 return -EFAULT;
 507
 508         if (!uprog.len) {
 509                 *p = NULL;
 510                 return 0;
 511         }
 512
 513         len = uprog.len * sizeof(struct sock_filter);
 514         code = kmalloc(len, GFP_KERNEL);
 515         if (code == NULL)
 516                 return -ENOMEM;
 517
 518         if (copy_from_user(code, uprog.filter, len)) {
 519                 kfree(code);
 520                 return -EFAULT;
 521         }
 522
 523         err = sk_chk_filter(code, uprog.len);
 524         if (err) {
 525                 kfree(code);
 526                 return err;
 527         }
 528
 529         *p = code;
 530         return uprog.len;
 531 }
 532 #endif /* CONFIG_PPP_FILTER */
 533
 534 static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 535 {
 536         struct ppp_file *pf = file->private_data;
 537         struct ppp *ppp;
 538         int err = -EFAULT, val, val2, i;
 539         struct ppp_idle idle;
 540         struct npioctl npi;
 541         int unit, cflags;
 542         struct slcompress *vj;
 543         void __user *argp = (void __user *)arg;
 544         int __user *p = argp;
 545
 546         if (!pf)
 547                 return ppp_unattached_ioctl(pf, file, cmd, arg);
 548
 549         if (cmd == PPPIOCDETACH) {
 550                 /*
 551                  * We have to be careful here... if the file descriptor
 552                  * has been dup'd, we could have another process in the
 553                  * middle of a poll using the same file *, so we had
 554                  * better not free the interface data structures -
 555                  * instead we fail the ioctl.  Even in this case, we
 556                  * shut down the interface if we are the owner of it.
 557                  * Actually, we should get rid of PPPIOCDETACH, userland
 558                  * (i.e. pppd) could achieve the same effect by closing
 559                  * this fd and reopening /dev/ppp.
 560                  */
 561                 err = -EINVAL;
 562                 lock_kernel();
 563                 if (pf->kind == INTERFACE) {
 564                         ppp = PF_TO_PPP(pf);
 565                         if (file == ppp->owner)
 566                                 ppp_shutdown_interface(ppp);
 567                 }
 568                 if (atomic_long_read(&file->f_count) <= 2) {
 569                         ppp_release(NULL, file);
 570                         err = 0;
 571                 } else
 572                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%ld\n",
 573                                atomic_long_read(&file->f_count));
 574                 unlock_kernel();
 575                 return err;
 576         }
 577
 578         if (pf->kind == CHANNEL) {
 579                 struct channel *pch;
 580                 struct ppp_channel *chan;
 581
 582                 lock_kernel();
 583                 pch = PF_TO_CHANNEL(pf);
 584
 585                 switch (cmd) {
 586                 case PPPIOCCONNECT:
 587                         if (get_user(unit, p))
 588                                 break;
 589                         err = ppp_connect_channel(pch, unit);
 590                         break;
 591
 592                 case PPPIOCDISCONN:
 593                         err = ppp_disconnect_channel(pch);
 594                         break;
 595
 596                 default:
 597                         down_read(&pch->chan_sem);
 598                         chan = pch->chan;
 599                         err = -ENOTTY;
 600                         if (chan && chan->ops->ioctl)
 601                                 err = chan->ops->ioctl(chan, cmd, arg);
 602                         up_read(&pch->chan_sem);
 603                 }
 604                 unlock_kernel();
 605                 return err;
 606         }
 607
 608         if (pf->kind != INTERFACE) {
 609                 /* can't happen */
 610                 printk(KERN_ERR "PPP: not interface or channel??\n");
 611                 return -EINVAL;
 612         }
 613
 614         lock_kernel();
 615         ppp = PF_TO_PPP(pf);
 616         switch (cmd) {
 617         case PPPIOCSMRU:
 618                 if (get_user(val, p))
 619                         break;
 620                 ppp->mru = val;
 621                 err = 0;
 622                 break;
 623
 624         case PPPIOCSFLAGS:
 625                 if (get_user(val, p))
 626                         break;
 627                 ppp_lock(ppp);
 628                 cflags = ppp->flags & ~val;
 629                 ppp->flags = val & SC_FLAG_BITS;
 630                 ppp_unlock(ppp);
 631                 if (cflags & SC_CCP_OPEN)
 632                         ppp_ccp_closed(ppp);
 633                 err = 0;
 634                 break;
 635
 636         case PPPIOCGFLAGS:
 637                 val = ppp->flags | ppp->xstate | ppp->rstate;
 638                 if (put_user(val, p))
 639                         break;
 640                 err = 0;
 641                 break;
 642
 643         case PPPIOCSCOMPRESS:
 644                 err = ppp_set_compress(ppp, arg);
 645                 break;
 646
 647         case PPPIOCGUNIT:
 648                 if (put_user(ppp->file.index, p))
 649                         break;
 650                 err = 0;
 651                 break;
 652
 653         case PPPIOCSDEBUG:
 654                 if (get_user(val, p))
 655                         break;
 656                 ppp->debug = val;
 657                 err = 0;
 658                 break;
 659
 660         case PPPIOCGDEBUG:
 661                 if (put_user(ppp->debug, p))
 662                         break;
 663                 err = 0;
 664                 break;
 665
 666         case PPPIOCGIDLE:
 667                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 668                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
 669                 if (copy_to_user(argp, &idle, sizeof(idle)))
 670                         break;
 671                 err = 0;
 672                 break;
 673
 674         case PPPIOCSMAXCID:
 675                 if (get_user(val, p))
 676                         break;
 677                 val2 = 15;
 678                 if ((val >> 16) != 0) {
 679                         val2 = val >> 16;
 680                         val &= 0xffff;
 681                 }
 682                 vj = slhc_init(val2+1, val+1);
 683                 if (!vj) {
 684                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
 685                         err = -ENOMEM;
 686                         break;
 687                 }
 688                 ppp_lock(ppp);
 689                 if (ppp->vj)
 690                         slhc_free(ppp->vj);
 691                 ppp->vj = vj;
 692                 ppp_unlock(ppp);
 693                 err = 0;
 694                 break;
 695
 696         case PPPIOCGNPMODE:
 697         case PPPIOCSNPMODE:
 698                 if (copy_from_user(&npi, argp, sizeof(npi)))
 699                         break;
 700                 err = proto_to_npindex(npi.protocol);
 701                 if (err < 0)
 702                         break;
 703                 i = err;
 704                 if (cmd == PPPIOCGNPMODE) {
 705                         err = -EFAULT;
 706                         npi.mode = ppp->npmode[i];
 707                         if (copy_to_user(argp, &npi, sizeof(npi)))
 708                                 break;
 709                 } else {
 710                         ppp->npmode[i] = npi.mode;
 711                         /* we may be able to transmit more packets now (??) */
 712                         netif_wake_queue(ppp->dev);
 713                 }
 714                 err = 0;
 715                 break;
 716
 717 #ifdef CONFIG_PPP_FILTER
 718         case PPPIOCSPASS:
 719         {
 720                 struct sock_filter *code;
 721                 err = get_filter(argp, &code);
 722                 if (err >= 0) {
 723                         ppp_lock(ppp);
 724                         kfree(ppp->pass_filter);
 725                         ppp->pass_filter = code;
 726                         ppp->pass_len = err;
 727                         ppp_unlock(ppp);
 728                         err = 0;
 729                 }
 730                 break;
 731         }
 732         case PPPIOCSACTIVE:
 733         {
 734                 struct sock_filter *code;
 735                 err = get_filter(argp, &code);
 736                 if (err >= 0) {
 737                         ppp_lock(ppp);
 738                         kfree(ppp->active_filter);
 739                         ppp->active_filter = code;
 740                         ppp->active_len = err;
 741                         ppp_unlock(ppp);
 742                         err = 0;
 743                 }
 744                 break;
 745         }
 746 #endif /* CONFIG_PPP_FILTER */
 747
 748 #ifdef CONFIG_PPP_MULTILINK
 749         case PPPIOCSMRRU:
 750                 if (get_user(val, p))
 751                         break;
 752                 ppp_recv_lock(ppp);
 753                 ppp->mrru = val;
 754                 ppp_recv_unlock(ppp);
 755                 err = 0;
 756                 break;
 757 #endif /* CONFIG_PPP_MULTILINK */
 758
 759         default:
 760                 err = -ENOTTY;
 761         }
 762         unlock_kernel();
 763         return err;
 764 }
 765
 766 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
 767                                 unsigned int cmd, unsigned long arg)
 768 {
 769         int unit, err = -EFAULT;
 770         struct ppp *ppp;
 771         struct channel *chan;
 772         int __user *p = (int __user *)arg;
 773
 774         lock_kernel();
 775         switch (cmd) {
 776         case PPPIOCNEWUNIT:
 777                 /* Create a new ppp unit */
 778                 if (get_user(unit, p))
 779                         break;
 780                 ppp = ppp_create_interface(unit, &err);
 781                 if (!ppp)
 782                         break;
 783                 file->private_data = &ppp->file;
 784                 ppp->owner = file;
 785                 err = -EFAULT;
 786                 if (put_user(ppp->file.index, p))
 787                         break;
 788                 err = 0;
 789                 break;
 790
 791         case PPPIOCATTACH:
 792                 /* Attach to an existing ppp unit */
 793                 if (get_user(unit, p))
 794                         break;
 795                 mutex_lock(&all_ppp_mutex);
 796                 err = -ENXIO;
 797                 ppp = ppp_find_unit(unit);
 798                 if (ppp) {
 799                         atomic_inc(&ppp->file.refcnt);
 800                         file->private_data = &ppp->file;
 801                         err = 0;
 802                 }
 803                 mutex_unlock(&all_ppp_mutex);
 804                 break;
 805
 806         case PPPIOCATTCHAN:
 807                 if (get_user(unit, p))
 808                         break;
 809                 spin_lock_bh(&all_channels_lock);
 810                 err = -ENXIO;
 811                 chan = ppp_find_channel(unit);
 812                 if (chan) {
 813                         atomic_inc(&chan->file.refcnt);
 814                         file->private_data = &chan->file;
 815                         err = 0;
 816                 }
 817                 spin_unlock_bh(&all_channels_lock);
 818                 break;
 819
 820         default:
 821                 err = -ENOTTY;
 822         }
 823         unlock_kernel();
 824         return err;
 825 }
 826
 827 static const struct file_operations ppp_device_fops = {
 828         .owner          = THIS_MODULE,
 829         .read           = ppp_read,
 830         .write          = ppp_write,
 831         .poll           = ppp_poll,
 832         .unlocked_ioctl = ppp_ioctl,
 833         .open           = ppp_open,
 834         .release        = ppp_release
 835 };
 836
 837 #define PPP_MAJOR       108
 838
 839 /* Called at boot time if ppp is compiled into the kernel,
 840    or at module load time (from init_module) if compiled as a module. */
 841 static int __init ppp_init(void)
 842 {
 843         int err;
 844
 845         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
 846         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
 847         if (!err) {
 848                 ppp_class = class_create(THIS_MODULE, "ppp");
 849                 if (IS_ERR(ppp_class)) {
 850                         err = PTR_ERR(ppp_class);
 851                         goto out_chrdev;
 852                 }
 853                 device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL,
 854                               "ppp");
 855         }
 856
 857 out:
 858         if (err)
 859                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
 860         return err;
 861
 862 out_chrdev:
 863         unregister_chrdev(PPP_MAJOR, "ppp");
 864         goto out;
 865 }
 866
 867 /*
 868  * Network interface unit routines.
 869  */
 870 static int
 871 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 872 {
 873         struct ppp *ppp = netdev_priv(dev);
 874         int npi, proto;
 875         unsigned char *pp;
 876
 877         npi = ethertype_to_npindex(ntohs(skb->protocol));
 878         if (npi < 0)
 879                 goto outf;
 880
 881         /* Drop, accept or reject the packet */
 882         switch (ppp->npmode[npi]) {
 883         case NPMODE_PASS:
 884                 break;
 885         case NPMODE_QUEUE:
 886                 /* it would be nice to have a way to tell the network
 887                    system to queue this one up for later. */
 888                 goto outf;
 889         case NPMODE_DROP:
 890         case NPMODE_ERROR:
 891                 goto outf;
 892         }
 893
 894         /* Put the 2-byte PPP protocol number on the front,
 895            making sure there is room for the address and control fields. */
 896         if (skb_cow_head(skb, PPP_HDRLEN))
 897                 goto outf;
 898
 899         pp = skb_push(skb, 2);
 900         proto = npindex_to_proto[npi];
 901         pp[0] = proto >> 8;
 902         pp[1] = proto;
 903
 904         netif_stop_queue(dev);
 905         skb_queue_tail(&ppp->file.xq, skb);
 906         ppp_xmit_process(ppp);
 907         return 0;
 908
 909  outf:
 910         kfree_skb(skb);
 911         ++ppp->dev->stats.tx_dropped;
 912         return 0;
 913 }
 914
 915 static int
 916 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 917 {
 918         struct ppp *ppp = netdev_priv(dev);
 919         int err = -EFAULT;
 920         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
 921         struct ppp_stats stats;
 922         struct ppp_comp_stats cstats;
 923         char *vers;
 924
 925         switch (cmd) {
 926         case SIOCGPPPSTATS:
 927                 ppp_get_stats(ppp, &stats);
 928                 if (copy_to_user(addr, &stats, sizeof(stats)))
 929                         break;
 930                 err = 0;
 931                 break;
 932
 933         case SIOCGPPPCSTATS:
 934                 memset(&cstats, 0, sizeof(cstats));
 935                 if (ppp->xc_state)
 936                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
 937                 if (ppp->rc_state)
 938                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
 939                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
 940                         break;
 941                 err = 0;
 942                 break;
 943
 944         case SIOCGPPPVER:
 945                 vers = PPP_VERSION;
 946                 if (copy_to_user(addr, vers, strlen(vers) + 1))
 947                         break;
 948                 err = 0;
 949                 break;
 950
 951         default:
 952                 err = -EINVAL;
 953         }
 954
 955         return err;
 956 }
 957
 958 static const struct net_device_ops ppp_netdev_ops = {
 959         .ndo_start_xmit = ppp_start_xmit,
 960         .ndo_do_ioctl   = ppp_net_ioctl,
 961 };
 962
 963 static void ppp_setup(struct net_device *dev)
 964 {
 965         dev->netdev_ops = &ppp_netdev_ops;
 966         dev->hard_header_len = PPP_HDRLEN;
 967         dev->mtu = PPP_MTU;
 968         dev->addr_len = 0;
 969         dev->tx_queue_len = 3;
 970         dev->type = ARPHRD_PPP;
 971         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
 972 }
 973
 974 /*
 975  * Transmit-side routines.
 976  */
 977
 978 /*
 979  * Called to do any work queued up on the transmit side
 980  * that can now be done.
 981  */
 982 static void
 983 ppp_xmit_process(struct ppp *ppp)
 984 {
 985         struct sk_buff *skb;
 986
 987         ppp_xmit_lock(ppp);
 988         if (!ppp->closing) {
 989                 ppp_push(ppp);
 990                 while (!ppp->xmit_pending
 991                        && (skb = skb_dequeue(&ppp->file.xq)))
 992                         ppp_send_frame(ppp, skb);
 993                 /* If there's no work left to do, tell the core net
 994                    code that we can accept some more. */
 995                 if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
 996                         netif_wake_queue(ppp->dev);
 997         }
 998         ppp_xmit_unlock(ppp);
 999 }
1000
1001 static inline struct sk_buff *
1002 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1003 {
1004         struct sk_buff *new_skb;
1005         int len;
1006         int new_skb_size = ppp->dev->mtu +
1007                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1008         int compressor_skb_size = ppp->dev->mtu +
1009                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1010         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1011         if (!new_skb) {
1012                 if (net_ratelimit())
1013                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1014                 return NULL;
1015         }
1016         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1017                 skb_reserve(new_skb,
1018                             ppp->dev->hard_header_len - PPP_HDRLEN);
1019
1020         /* compressor still expects A/C bytes in hdr */
1021         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1022                                    new_skb->data, skb->len + 2,
1023                                    compressor_skb_size);
1024         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1025                 kfree_skb(skb);
1026                 skb = new_skb;
1027                 skb_put(skb, len);
1028                 skb_pull(skb, 2);       /* pull off A/C bytes */
1029         } else if (len == 0) {
1030                 /* didn't compress, or CCP not up yet */
1031                 kfree_skb(new_skb);
1032                 new_skb = skb;
1033         } else {
1034                 /*
1035                  * (len < 0)
1036                  * MPPE requires that we do not send unencrypted
1037                  * frames.  The compressor will return -1 if we
1038                  * should drop the frame.  We cannot simply test
1039                  * the compress_proto because MPPE and MPPC share
1040                  * the same number.
1041                  */
1042                 if (net_ratelimit())
1043                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1044                 kfree_skb(skb);
1045                 kfree_skb(new_skb);
1046                 new_skb = NULL;
1047         }
1048         return new_skb;
1049 }
1050
1051 /*
1052  * Compress and send a frame.
1053  * The caller should have locked the xmit path,
1054  * and xmit_pending should be 0.
1055  */
1056 static void
1057 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1058 {
1059         int proto = PPP_PROTO(skb);
1060         struct sk_buff *new_skb;
1061         int len;
1062         unsigned char *cp;
1063
1064         if (proto < 0x8000) {
1065 #ifdef CONFIG_PPP_FILTER
1066                 /* check if we should pass this packet */
1067                 /* the filter instructions are constructed assuming
1068                    a four-byte PPP header on each packet */
1069                 *skb_push(skb, 2) = 1;
1070                 if (ppp->pass_filter
1071                     && sk_run_filter(skb, ppp->pass_filter,
1072                                      ppp->pass_len) == 0) {
1073                         if (ppp->debug & 1)
1074                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1075                         kfree_skb(skb);
1076                         return;
1077                 }
1078                 /* if this packet passes the active filter, record the time */
1079                 if (!(ppp->active_filter
1080                       && sk_run_filter(skb, ppp->active_filter,
1081                                        ppp->active_len) == 0))
1082                         ppp->last_xmit = jiffies;
1083                 skb_pull(skb, 2);
1084 #else
1085                 /* for data packets, record the time */
1086                 ppp->last_xmit = jiffies;
1087 #endif /* CONFIG_PPP_FILTER */
1088         }
1089
1090         ++ppp->dev->stats.tx_packets;
1091         ppp->dev->stats.tx_bytes += skb->len - 2;
1092
1093         switch (proto) {
1094         case PPP_IP:
1095                 if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1096                         break;
1097                 /* try to do VJ TCP header compression */
1098                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1099                                     GFP_ATOMIC);
1100                 if (!new_skb) {
1101                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1102                         goto drop;
1103                 }
1104                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1105                 cp = skb->data + 2;
1106                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1107                                     new_skb->data + 2, &cp,
1108                                     !(ppp->flags & SC_NO_TCP_CCID));
1109                 if (cp == skb->data + 2) {
1110                         /* didn't compress */
1111                         kfree_skb(new_skb);
1112                 } else {
1113                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1114                                 proto = PPP_VJC_COMP;
1115                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1116                         } else {
1117                                 proto = PPP_VJC_UNCOMP;
1118                                 cp[0] = skb->data[2];
1119                         }
1120                         kfree_skb(skb);
1121                         skb = new_skb;
1122                         cp = skb_put(skb, len + 2);
1123                         cp[0] = 0;
1124                         cp[1] = proto;
1125                 }
1126                 break;
1127
1128         case PPP_CCP:
1129                 /* peek at outbound CCP frames */
1130                 ppp_ccp_peek(ppp, skb, 0);
1131                 break;
1132         }
1133
1134         /* try to do packet compression */
1135         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state
1136             && proto != PPP_LCP && proto != PPP_CCP) {
1137                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1138                         if (net_ratelimit())
1139                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1140                         goto drop;
1141                 }
1142                 skb = pad_compress_skb(ppp, skb);
1143                 if (!skb)
1144                         goto drop;
1145         }
1146
1147         /*
1148          * If we are waiting for traffic (demand dialling),
1149          * queue it up for pppd to receive.
1150          */
1151         if (ppp->flags & SC_LOOP_TRAFFIC) {
1152                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1153                         goto drop;
1154                 skb_queue_tail(&ppp->file.rq, skb);
1155                 wake_up_interruptible(&ppp->file.rwait);
1156                 return;
1157         }
1158
1159         ppp->xmit_pending = skb;
1160         ppp_push(ppp);
1161         return;
1162
1163  drop:
1164         if (skb)
1165                 kfree_skb(skb);
1166         ++ppp->dev->stats.tx_errors;
1167 }
1168
1169 /*
1170  * Try to send the frame in xmit_pending.
1171  * The caller should have the xmit path locked.
1172  */
1173 static void
1174 ppp_push(struct ppp *ppp)
1175 {
1176         struct list_head *list;
1177         struct channel *pch;
1178         struct sk_buff *skb = ppp->xmit_pending;
1179
1180         if (!skb)
1181                 return;
1182
1183         list = &ppp->channels;
1184         if (list_empty(list)) {
1185                 /* nowhere to send the packet, just drop it */
1186                 ppp->xmit_pending = NULL;
1187                 kfree_skb(skb);
1188                 return;
1189         }
1190
1191         if ((ppp->flags & SC_MULTILINK) == 0) {
1192                 /* not doing multilink: send it down the first channel */
1193                 list = list->next;
1194                 pch = list_entry(list, struct channel, clist);
1195
1196                 spin_lock_bh(&pch->downl);
1197                 if (pch->chan) {
1198                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1199                                 ppp->xmit_pending = NULL;
1200                 } else {
1201                         /* channel got unregistered */
1202                         kfree_skb(skb);
1203                         ppp->xmit_pending = NULL;
1204                 }
1205                 spin_unlock_bh(&pch->downl);
1206                 return;
1207         }
1208
1209 #ifdef CONFIG_PPP_MULTILINK
1210         /* Multilink: fragment the packet over as many links
1211            as can take the packet at the moment. */
1212         if (!ppp_mp_explode(ppp, skb))
1213                 return;
1214 #endif /* CONFIG_PPP_MULTILINK */
1215
1216         ppp->xmit_pending = NULL;
1217         kfree_skb(skb);
1218 }
1219
1220 #ifdef CONFIG_PPP_MULTILINK
1221 /*
1222  * Divide a packet to be transmitted into fragments and
1223  * send them out the individual links.
1224  */
1225 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1226 {
1227         int len, fragsize;
1228         int i, bits, hdrlen, mtu;
1229         int flen;
1230         int navail, nfree;
1231         int nbigger;
1232         unsigned char *p, *q;
1233         struct list_head *list;
1234         struct channel *pch;
1235         struct sk_buff *frag;
1236         struct ppp_channel *chan;
1237
1238         nfree = 0;      /* # channels which have no packet already queued */
1239         navail = 0;     /* total # of usable channels (not deregistered) */
1240         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1241         i = 0;
1242         list_for_each_entry(pch, &ppp->channels, clist) {
1243                 navail += pch->avail = (pch->chan != NULL);
1244                 if (pch->avail) {
1245                         if (skb_queue_empty(&pch->file.xq) ||
1246                             !pch->had_frag) {
1247                                 pch->avail = 2;
1248                                 ++nfree;
1249                         }
1250                         if (!pch->had_frag && i < ppp->nxchan)
1251                                 ppp->nxchan = i;
1252                 }
1253                 ++i;
1254         }
1255
1256         /*
1257          * Don't start sending this packet unless at least half of
1258          * the channels are free.  This gives much better TCP
1259          * performance if we have a lot of channels.
1260          */
1261         if (nfree == 0 || nfree < navail / 2)
1262                 return 0;       /* can't take now, leave it in xmit_pending */
1263
1264         /* Do protocol field compression (XXX this should be optional) */
1265         p = skb->data;
1266         len = skb->len;
1267         if (*p == 0) {
1268                 ++p;
1269                 --len;
1270         }
1271
1272         /*
1273          * Decide on fragment size.
1274          * We create a fragment for each free channel regardless of
1275          * how small they are (i.e. even 0 length) in order to minimize
1276          * the time that it will take to detect when a channel drops
1277          * a fragment.
1278          */
1279         fragsize = len;
1280         if (nfree > 1)
1281                 fragsize = DIV_ROUND_UP(fragsize, nfree);
1282         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1283            except if nbigger==0, then they all get fragsize. */
1284         nbigger = len % nfree;
1285
1286         /* skip to the channel after the one we last used
1287            and start at that one */
1288         list = &ppp->channels;
1289         for (i = 0; i < ppp->nxchan; ++i) {
1290                 list = list->next;
1291                 if (list == &ppp->channels) {
1292                         i = 0;
1293                         break;
1294                 }
1295         }
1296
1297         /* create a fragment for each channel */
1298         bits = B;
1299         while (nfree > 0 || len > 0) {
1300                 list = list->next;
1301                 if (list == &ppp->channels) {
1302                         i = 0;
1303                         continue;
1304                 }
1305                 pch = list_entry(list, struct channel, clist);
1306                 ++i;
1307                 if (!pch->avail)
1308                         continue;
1309
1310                 /*
1311                  * Skip this channel if it has a fragment pending already and
1312                  * we haven't given a fragment to all of the free channels.
1313                  */
1314                 if (pch->avail == 1) {
1315                         if (nfree > 0)
1316                                 continue;
1317                 } else {
1318                         --nfree;
1319                         pch->avail = 1;
1320                 }
1321
1322                 /* check the channel's mtu and whether it is still attached. */
1323                 spin_lock_bh(&pch->downl);
1324                 if (pch->chan == NULL) {
1325                         /* can't use this channel, it's being deregistered */
1326                         spin_unlock_bh(&pch->downl);
1327                         pch->avail = 0;
1328                         if (--navail == 0)
1329                                 break;
1330                         continue;
1331                 }
1332
1333                 /*
1334                  * Create a fragment for this channel of
1335                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1336                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1337                  * MTU, so we use mtu = 2 + hdrlen.
1338                  */
1339                 if (fragsize > len)
1340                         fragsize = len;
1341                 flen = fragsize;
1342                 mtu = pch->chan->mtu + 2 - hdrlen;
1343                 if (mtu < 4)
1344                         mtu = 4;
1345                 if (flen > mtu)
1346                         flen = mtu;
1347                 if (flen == len && nfree == 0)
1348                         bits |= E;
1349                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1350                 if (!frag)
1351                         goto noskb;
1352                 q = skb_put(frag, flen + hdrlen);
1353
1354                 /* make the MP header */
1355                 q[0] = PPP_MP >> 8;
1356                 q[1] = PPP_MP;
1357                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1358                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1359                         q[3] = ppp->nxseq;
1360                 } else {
1361                         q[2] = bits;
1362                         q[3] = ppp->nxseq >> 16;
1363                         q[4] = ppp->nxseq >> 8;
1364                         q[5] = ppp->nxseq;
1365                 }
1366
1367                 /*
1368                  * Copy the data in.
1369                  * Unfortunately there is a bug in older versions of
1370                  * the Linux PPP multilink reconstruction code where it
1371                  * drops 0-length fragments.  Therefore we make sure the
1372                  * fragment has at least one byte of data.  Any bytes
1373                  * we add in this situation will end up as padding on the
1374                  * end of the reconstructed packet.
1375                  */
1376                 if (flen == 0)
1377                         *skb_put(frag, 1) = 0;
1378                 else
1379                         memcpy(q + hdrlen, p, flen);
1380
1381                 /* try to send it down the channel */
1382                 chan = pch->chan;
1383                 if (!skb_queue_empty(&pch->file.xq) ||
1384                     !chan->ops->start_xmit(chan, frag))
1385                         skb_queue_tail(&pch->file.xq, frag);
1386                 pch->had_frag = 1;
1387                 p += flen;
1388                 len -= flen;
1389                 ++ppp->nxseq;
1390                 bits = 0;
1391                 spin_unlock_bh(&pch->downl);
1392
1393                 if (--nbigger == 0 && fragsize > 0)
1394                         --fragsize;
1395         }
1396         ppp->nxchan = i;
1397
1398         return 1;
1399
1400  noskb:
1401         spin_unlock_bh(&pch->downl);
1402         if (ppp->debug & 1)
1403                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1404         ++ppp->dev->stats.tx_errors;
1405         ++ppp->nxseq;
1406         return 1;       /* abandon the frame */
1407 }
1408 #endif /* CONFIG_PPP_MULTILINK */
1409
1410 /*
1411  * Try to send data out on a channel.
1412  */
1413 static void
1414 ppp_channel_push(struct channel *pch)
1415 {
1416         struct sk_buff *skb;
1417         struct ppp *ppp;
1418
1419         spin_lock_bh(&pch->downl);
1420         if (pch->chan) {
1421                 while (!skb_queue_empty(&pch->file.xq)) {
1422                         skb = skb_dequeue(&pch->file.xq);
1423                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1424                                 /* put the packet back and try again later */
1425                                 skb_queue_head(&pch->file.xq, skb);
1426                                 break;
1427                         }
1428                 }
1429         } else {
1430                 /* channel got deregistered */
1431                 skb_queue_purge(&pch->file.xq);
1432         }
1433         spin_unlock_bh(&pch->downl);
1434         /* see if there is anything from the attached unit to be sent */
1435         if (skb_queue_empty(&pch->file.xq)) {
1436                 read_lock_bh(&pch->upl);
1437                 ppp = pch->ppp;
1438                 if (ppp)
1439                         ppp_xmit_process(ppp);
1440                 read_unlock_bh(&pch->upl);
1441         }
1442 }
1443
1444 /*
1445  * Receive-side routines.
1446  */
1447
1448 /* misuse a few fields of the skb for MP reconstruction */
1449 #define sequence        priority
1450 #define BEbits          cb[0]
1451
1452 static inline void
1453 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1454 {
1455         ppp_recv_lock(ppp);
1456         if (!ppp->closing)
1457                 ppp_receive_frame(ppp, skb, pch);
1458         else
1459                 kfree_skb(skb);
1460         ppp_recv_unlock(ppp);
1461 }
1462
1463 void
1464 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1465 {
1466         struct channel *pch = chan->ppp;
1467         int proto;
1468
1469         if (!pch || skb->len == 0) {
1470                 kfree_skb(skb);
1471                 return;
1472         }
1473
1474         proto = PPP_PROTO(skb);
1475         read_lock_bh(&pch->upl);
1476         if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1477                 /* put it on the channel queue */
1478                 skb_queue_tail(&pch->file.rq, skb);
1479                 /* drop old frames if queue too long */
1480                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1481                        && (skb = skb_dequeue(&pch->file.rq)))
1482                         kfree_skb(skb);
1483                 wake_up_interruptible(&pch->file.rwait);
1484         } else {
1485                 ppp_do_recv(pch->ppp, skb, pch);
1486         }
1487         read_unlock_bh(&pch->upl);
1488 }
1489
1490 /* Put a 0-length skb in the receive queue as an error indication */
1491 void
1492 ppp_input_error(struct ppp_channel *chan, int code)
1493 {
1494         struct channel *pch = chan->ppp;
1495         struct sk_buff *skb;
1496
1497         if (!pch)
1498                 return;
1499
1500         read_lock_bh(&pch->upl);
1501         if (pch->ppp) {
1502                 skb = alloc_skb(0, GFP_ATOMIC);
1503                 if (skb) {
1504                         skb->len = 0;           /* probably unnecessary */
1505                         skb->cb[0] = code;
1506                         ppp_do_recv(pch->ppp, skb, pch);
1507                 }
1508         }
1509         read_unlock_bh(&pch->upl);
1510 }
1511
1512 /*
1513  * We come in here to process a received frame.
1514  * The receive side of the ppp unit is locked.
1515  */
1516 static void
1517 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1518 {
1519         if (pskb_may_pull(skb, 2)) {
1520 #ifdef CONFIG_PPP_MULTILINK
1521                 /* XXX do channel-level decompression here */
1522                 if (PPP_PROTO(skb) == PPP_MP)
1523                         ppp_receive_mp_frame(ppp, skb, pch);
1524                 else
1525 #endif /* CONFIG_PPP_MULTILINK */
1526                         ppp_receive_nonmp_frame(ppp, skb);
1527                 return;
1528         }
1529
1530         if (skb->len > 0)
1531                 /* note: a 0-length skb is used as an error indication */
1532                 ++ppp->dev->stats.rx_length_errors;
1533
1534         kfree_skb(skb);
1535         ppp_receive_error(ppp);
1536 }
1537
1538 static void
1539 ppp_receive_error(struct ppp *ppp)
1540 {
1541         ++ppp->dev->stats.rx_errors;
1542         if (ppp->vj)
1543                 slhc_toss(ppp->vj);
1544 }
1545
1546 static void
1547 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1548 {
1549         struct sk_buff *ns;
1550         int proto, len, npi;
1551
1552         /*
1553          * Decompress the frame, if compressed.
1554          * Note that some decompressors need to see uncompressed frames
1555          * that come in as well as compressed frames.
1556          */
1557         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)
1558             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1559                 skb = ppp_decompress_frame(ppp, skb);
1560
1561         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1562                 goto err;
1563
1564         proto = PPP_PROTO(skb);
1565         switch (proto) {
1566         case PPP_VJC_COMP:
1567                 /* decompress VJ compressed packets */
1568                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1569                         goto err;
1570
1571                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1572                         /* copy to a new sk_buff with more tailroom */
1573                         ns = dev_alloc_skb(skb->len + 128);
1574                         if (!ns) {
1575                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1576                                 goto err;
1577                         }
1578                         skb_reserve(ns, 2);
1579                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1580                         kfree_skb(skb);
1581                         skb = ns;
1582                 }
1583                 else
1584                         skb->ip_summed = CHECKSUM_NONE;
1585
1586                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1587                 if (len <= 0) {
1588                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1589                         goto err;
1590                 }
1591                 len += 2;
1592                 if (len > skb->len)
1593                         skb_put(skb, len - skb->len);
1594                 else if (len < skb->len)
1595                         skb_trim(skb, len);
1596                 proto = PPP_IP;
1597                 break;
1598
1599         case PPP_VJC_UNCOMP:
1600                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1601                         goto err;
1602
1603                 /* Until we fix the decompressor need to make sure
1604                  * data portion is linear.
1605                  */
1606                 if (!pskb_may_pull(skb, skb->len))
1607                         goto err;
1608
1609                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1610                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1611                         goto err;
1612                 }
1613                 proto = PPP_IP;
1614                 break;
1615
1616         case PPP_CCP:
1617                 ppp_ccp_peek(ppp, skb, 1);
1618                 break;
1619         }
1620
1621         ++ppp->dev->stats.rx_packets;
1622         ppp->dev->stats.rx_bytes += skb->len - 2;
1623
1624         npi = proto_to_npindex(proto);
1625         if (npi < 0) {
1626                 /* control or unknown frame - pass it to pppd */
1627                 skb_queue_tail(&ppp->file.rq, skb);
1628                 /* limit queue length by dropping old frames */
1629                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1630                        && (skb = skb_dequeue(&ppp->file.rq)))
1631                         kfree_skb(skb);
1632                 /* wake up any process polling or blocking on read */
1633                 wake_up_interruptible(&ppp->file.rwait);
1634
1635         } else {
1636                 /* network protocol frame - give it to the kernel */
1637
1638 #ifdef CONFIG_PPP_FILTER
1639                 /* check if the packet passes the pass and active filters */
1640                 /* the filter instructions are constructed assuming
1641                    a four-byte PPP header on each packet */
1642                 if (ppp->pass_filter || ppp->active_filter) {
1643                         if (skb_cloned(skb) &&
1644                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
1645                                 goto err;
1646
1647                         *skb_push(skb, 2) = 0;
1648                         if (ppp->pass_filter
1649                             && sk_run_filter(skb, ppp->pass_filter,
1650                                              ppp->pass_len) == 0) {
1651                                 if (ppp->debug & 1)
1652                                         printk(KERN_DEBUG "PPP: inbound frame "
1653                                                "not passed\n");
1654                                 kfree_skb(skb);
1655                                 return;
1656                         }
1657                         if (!(ppp->active_filter
1658                               && sk_run_filter(skb, ppp->active_filter,
1659                                                ppp->active_len) == 0))
1660                                 ppp->last_recv = jiffies;
1661                         __skb_pull(skb, 2);
1662                 } else
1663 #endif /* CONFIG_PPP_FILTER */
1664                         ppp->last_recv = jiffies;
1665
1666                 if ((ppp->dev->flags & IFF_UP) == 0
1667                     || ppp->npmode[npi] != NPMODE_PASS) {
1668                         kfree_skb(skb);
1669                 } else {
1670                         /* chop off protocol */
1671                         skb_pull_rcsum(skb, 2);
1672                         skb->dev = ppp->dev;
1673                         skb->protocol = htons(npindex_to_ethertype[npi]);
1674                         skb_reset_mac_header(skb);
1675                         netif_rx(skb);
1676                 }
1677         }
1678         return;
1679
1680  err:
1681         kfree_skb(skb);
1682         ppp_receive_error(ppp);
1683 }
1684
1685 static struct sk_buff *
1686 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1687 {
1688         int proto = PPP_PROTO(skb);
1689         struct sk_buff *ns;
1690         int len;
1691
1692         /* Until we fix all the decompressor's need to make sure
1693          * data portion is linear.
1694          */
1695         if (!pskb_may_pull(skb, skb->len))
1696                 goto err;
1697
1698         if (proto == PPP_COMP) {
1699                 int obuff_size;
1700
1701                 switch(ppp->rcomp->compress_proto) {
1702                 case CI_MPPE:
1703                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1704                         break;
1705                 default:
1706                         obuff_size = ppp->mru + PPP_HDRLEN;
1707                         break;
1708                 }
1709
1710                 ns = dev_alloc_skb(obuff_size);
1711                 if (!ns) {
1712                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1713                         goto err;
1714                 }
1715                 /* the decompressor still expects the A/C bytes in the hdr */
1716                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1717                                 skb->len + 2, ns->data, obuff_size);
1718                 if (len < 0) {
1719                         /* Pass the compressed frame to pppd as an
1720                            error indication. */
1721                         if (len == DECOMP_FATALERROR)
1722                                 ppp->rstate |= SC_DC_FERROR;
1723                         kfree_skb(ns);
1724                         goto err;
1725                 }
1726
1727                 kfree_skb(skb);
1728                 skb = ns;
1729                 skb_put(skb, len);
1730                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1731
1732         } else {
1733                 /* Uncompressed frame - pass to decompressor so it
1734                    can update its dictionary if necessary. */
1735                 if (ppp->rcomp->incomp)
1736                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1737                                            skb->len + 2);
1738         }
1739
1740         return skb;
1741
1742  err:
1743         ppp->rstate |= SC_DC_ERROR;
1744         ppp_receive_error(ppp);
1745         return skb;
1746 }
1747
1748 #ifdef CONFIG_PPP_MULTILINK
1749 /*
1750  * Receive a multilink frame.
1751  * We put it on the reconstruction queue and then pull off
1752  * as many completed frames as we can.
1753  */
1754 static void
1755 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1756 {
1757         u32 mask, seq;
1758         struct channel *ch;
1759         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1760
1761         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1762                 goto err;               /* no good, throw it away */
1763
1764         /* Decode sequence number and begin/end bits */
1765         if (ppp->flags & SC_MP_SHORTSEQ) {
1766                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1767                 mask = 0xfff;
1768         } else {
1769                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1770                 mask = 0xffffff;
1771         }
1772         skb->BEbits = skb->data[2];
1773         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1774
1775         /*
1776          * Do protocol ID decompression on the first fragment of each packet.
1777          */
1778         if ((skb->BEbits & B) && (skb->data[0] & 1))
1779                 *skb_push(skb, 1) = 0;
1780
1781         /*
1782          * Expand sequence number to 32 bits, making it as close
1783          * as possible to ppp->minseq.
1784          */
1785         seq |= ppp->minseq & ~mask;
1786         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1787                 seq += mask + 1;
1788         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1789                 seq -= mask + 1;        /* should never happen */
1790         skb->sequence = seq;
1791         pch->lastseq = seq;
1792
1793         /*
1794          * If this packet comes before the next one we were expecting,
1795          * drop it.
1796          */
1797         if (seq_before(seq, ppp->nextseq)) {
1798                 kfree_skb(skb);
1799                 ++ppp->dev->stats.rx_dropped;
1800                 ppp_receive_error(ppp);
1801                 return;
1802         }
1803
1804         /*
1805          * Reevaluate minseq, the minimum over all channels of the
1806          * last sequence number received on each channel.  Because of
1807          * the increasing sequence number rule, we know that any fragment
1808          * before `minseq' which hasn't arrived is never going to arrive.
1809          * The list of channels can't change because we have the receive
1810          * side of the ppp unit locked.
1811          */
1812         list_for_each_entry(ch, &ppp->channels, clist) {
1813                 if (seq_before(ch->lastseq, seq))
1814                         seq = ch->lastseq;
1815         }
1816         if (seq_before(ppp->minseq, seq))
1817                 ppp->minseq = seq;
1818
1819         /* Put the fragment on the reconstruction queue */
1820         ppp_mp_insert(ppp, skb);
1821
1822         /* If the queue is getting long, don't wait any longer for packets
1823            before the start of the queue. */
1824         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN) {
1825                 struct sk_buff *skb = skb_peek(&ppp->mrq);
1826                 if (seq_before(ppp->minseq, skb->sequence))
1827                         ppp->minseq = skb->sequence;
1828         }
1829
1830         /* Pull completed packets off the queue and receive them. */
1831         while ((skb = ppp_mp_reconstruct(ppp)))
1832                 ppp_receive_nonmp_frame(ppp, skb);
1833
1834         return;
1835
1836  err:
1837         kfree_skb(skb);
1838         ppp_receive_error(ppp);
1839 }
1840
1841 /*
1842  * Insert a fragment on the MP reconstruction queue.
1843  * The queue is ordered by increasing sequence number.
1844  */
1845 static void
1846 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1847 {
1848         struct sk_buff *p;
1849         struct sk_buff_head *list = &ppp->mrq;
1850         u32 seq = skb->sequence;
1851
1852         /* N.B. we don't need to lock the list lock because we have the
1853            ppp unit receive-side lock. */
1854         skb_queue_walk(list, p) {
1855                 if (seq_before(seq, p->sequence))
1856                         break;
1857         }
1858         __skb_queue_before(list, p, skb);
1859 }
1860
1861 /*
1862  * Reconstruct a packet from the MP fragment queue.
1863  * We go through increasing sequence numbers until we find a
1864  * complete packet, or we get to the sequence number for a fragment
1865  * which hasn't arrived but might still do so.
1866  */
1867 static struct sk_buff *
1868 ppp_mp_reconstruct(struct ppp *ppp)
1869 {
1870         u32 seq = ppp->nextseq;
1871         u32 minseq = ppp->minseq;
1872         struct sk_buff_head *list = &ppp->mrq;
1873         struct sk_buff *p, *next;
1874         struct sk_buff *head, *tail;
1875         struct sk_buff *skb = NULL;
1876         int lost = 0, len = 0;
1877
1878         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1879                 return NULL;
1880         head = list->next;
1881         tail = NULL;
1882         for (p = head; p != (struct sk_buff *) list; p = next) {
1883                 next = p->next;
1884                 if (seq_before(p->sequence, seq)) {
1885                         /* this can't happen, anyway ignore the skb */
1886                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1887                                p->sequence, seq);
1888                         head = next;
1889                         continue;
1890                 }
1891                 if (p->sequence != seq) {
1892                         /* Fragment `seq' is missing.  If it is after
1893                            minseq, it might arrive later, so stop here. */
1894                         if (seq_after(seq, minseq))
1895                                 break;
1896                         /* Fragment `seq' is lost, keep going. */
1897                         lost = 1;
1898                         seq = seq_before(minseq, p->sequence)?
1899                                 minseq + 1: p->sequence;
1900                         next = p;
1901                         continue;
1902                 }
1903
1904                 /*
1905                  * At this point we know that all the fragments from
1906                  * ppp->nextseq to seq are either present or lost.
1907                  * Also, there are no complete packets in the queue
1908                  * that have no missing fragments and end before this
1909                  * fragment.
1910                  */
1911
1912                 /* B bit set indicates this fragment starts a packet */
1913                 if (p->BEbits & B) {
1914                         head = p;
1915                         lost = 0;
1916                         len = 0;
1917                 }
1918
1919                 len += p->len;
1920
1921                 /* Got a complete packet yet? */
1922                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1923                         if (len > ppp->mrru + 2) {
1924                                 ++ppp->dev->stats.rx_length_errors;
1925                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1926                                        " is too long (%d)\n", len);
1927                         } else if (p == head) {
1928                                 /* fragment is complete packet - reuse skb */
1929                                 tail = p;
1930                                 skb = skb_get(p);
1931                                 break;
1932                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1933                                 ++ppp->dev->stats.rx_missed_errors;
1934                                 printk(KERN_DEBUG "PPP: no memory for "
1935                                        "reconstructed packet");
1936                         } else {
1937                                 tail = p;
1938                                 break;
1939                         }
1940                         ppp->nextseq = seq + 1;
1941                 }
1942
1943                 /*
1944                  * If this is the ending fragment of a packet,
1945                  * and we haven't found a complete valid packet yet,
1946                  * we can discard up to and including this fragment.
1947                  */
1948                 if (p->BEbits & E)
1949                         head = next;
1950
1951                 ++seq;
1952         }
1953
1954         /* If we have a complete packet, copy it all into one skb. */
1955         if (tail != NULL) {
1956                 /* If we have discarded any fragments,
1957                    signal a receive error. */
1958                 if (head->sequence != ppp->nextseq) {
1959                         if (ppp->debug & 1)
1960                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1961                                        ppp->nextseq, head->sequence-1);
1962                         ++ppp->dev->stats.rx_dropped;
1963                         ppp_receive_error(ppp);
1964                 }
1965
1966                 if (head != tail)
1967                         /* copy to a single skb */
1968                         for (p = head; p != tail->next; p = p->next)
1969                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1970                 ppp->nextseq = tail->sequence + 1;
1971                 head = tail->next;
1972         }
1973
1974         /* Discard all the skbuffs that we have copied the data out of
1975            or that we can't use. */
1976         while ((p = list->next) != head) {
1977                 __skb_unlink(p, list);
1978                 kfree_skb(p);
1979         }
1980
1981         return skb;
1982 }
1983 #endif /* CONFIG_PPP_MULTILINK */
1984
1985 /*
1986  * Channel interface.
1987  */
1988
1989 /*
1990  * Create a new, unattached ppp channel.
1991  */
1992 int
1993 ppp_register_channel(struct ppp_channel *chan)
1994 {
1995         struct channel *pch;
1996
1997         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
1998         if (!pch)
1999                 return -ENOMEM;
2000         pch->ppp = NULL;
2001         pch->chan = chan;
2002         chan->ppp = pch;
2003         init_ppp_file(&pch->file, CHANNEL);
2004         pch->file.hdrlen = chan->hdrlen;
2005 #ifdef CONFIG_PPP_MULTILINK
2006         pch->lastseq = -1;
2007 #endif /* CONFIG_PPP_MULTILINK */
2008         init_rwsem(&pch->chan_sem);
2009         spin_lock_init(&pch->downl);
2010         rwlock_init(&pch->upl);
2011         spin_lock_bh(&all_channels_lock);
2012         pch->file.index = ++last_channel_index;
2013         list_add(&pch->list, &new_channels);
2014         atomic_inc(&channel_count);
2015         spin_unlock_bh(&all_channels_lock);
2016         return 0;
2017 }
2018
2019 /*
2020  * Return the index of a channel.
2021  */
2022 int ppp_channel_index(struct ppp_channel *chan)
2023 {
2024         struct channel *pch = chan->ppp;
2025
2026         if (pch)
2027                 return pch->file.index;
2028         return -1;
2029 }
2030
2031 /*
2032  * Return the PPP unit number to which a channel is connected.
2033  */
2034 int ppp_unit_number(struct ppp_channel *chan)
2035 {
2036         struct channel *pch = chan->ppp;
2037         int unit = -1;
2038
2039         if (pch) {
2040                 read_lock_bh(&pch->upl);
2041                 if (pch->ppp)
2042                         unit = pch->ppp->file.index;
2043                 read_unlock_bh(&pch->upl);
2044         }
2045         return unit;
2046 }
2047
2048 /*
2049  * Disconnect a channel from the generic layer.
2050  * This must be called in process context.
2051  */
2052 void
2053 ppp_unregister_channel(struct ppp_channel *chan)
2054 {
2055         struct channel *pch = chan->ppp;
2056
2057         if (!pch)
2058                 return;         /* should never happen */
2059         chan->ppp = NULL;
2060
2061         /*
2062          * This ensures that we have returned from any calls into the
2063          * the channel's start_xmit or ioctl routine before we proceed.
2064          */
2065         down_write(&pch->chan_sem);
2066         spin_lock_bh(&pch->downl);
2067         pch->chan = NULL;
2068         spin_unlock_bh(&pch->downl);
2069         up_write(&pch->chan_sem);
2070         ppp_disconnect_channel(pch);
2071         spin_lock_bh(&all_channels_lock);
2072         list_del(&pch->list);
2073         spin_unlock_bh(&all_channels_lock);
2074         pch->file.dead = 1;
2075         wake_up_interruptible(&pch->file.rwait);
2076         if (atomic_dec_and_test(&pch->file.refcnt))
2077                 ppp_destroy_channel(pch);
2078 }
2079
2080 /*
2081  * Callback from a channel when it can accept more to transmit.
2082  * This should be called at BH/softirq level, not interrupt level.
2083  */
2084 void
2085 ppp_output_wakeup(struct ppp_channel *chan)
2086 {
2087         struct channel *pch = chan->ppp;
2088
2089         if (!pch)
2090                 return;
2091         ppp_channel_push(pch);
2092 }
2093
2094 /*
2095  * Compression control.
2096  */
2097
2098 /* Process the PPPIOCSCOMPRESS ioctl. */
2099 static int
2100 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2101 {
2102         int err;
2103         struct compressor *cp, *ocomp;
2104         struct ppp_option_data data;
2105         void *state, *ostate;
2106         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2107
2108         err = -EFAULT;
2109         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2110             || (data.length <= CCP_MAX_OPTION_LENGTH
2111                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2112                 goto out;
2113         err = -EINVAL;
2114         if (data.length > CCP_MAX_OPTION_LENGTH
2115             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2116                 goto out;
2117
2118         cp = try_then_request_module(
2119                 find_compressor(ccp_option[0]),
2120                 "ppp-compress-%d", ccp_option[0]);
2121         if (!cp)
2122                 goto out;
2123
2124         err = -ENOBUFS;
2125         if (data.transmit) {
2126                 state = cp->comp_alloc(ccp_option, data.length);
2127                 if (state) {
2128                         ppp_xmit_lock(ppp);
2129                         ppp->xstate &= ~SC_COMP_RUN;
2130                         ocomp = ppp->xcomp;
2131                         ostate = ppp->xc_state;
2132                         ppp->xcomp = cp;
2133                         ppp->xc_state = state;
2134                         ppp_xmit_unlock(ppp);
2135                         if (ostate) {
2136                                 ocomp->comp_free(ostate);
2137                                 module_put(ocomp->owner);
2138                         }
2139                         err = 0;
2140                 } else
2141                         module_put(cp->owner);
2142
2143         } else {
2144                 state = cp->decomp_alloc(ccp_option, data.length);
2145                 if (state) {
2146                         ppp_recv_lock(ppp);
2147                         ppp->rstate &= ~SC_DECOMP_RUN;
2148                         ocomp = ppp->rcomp;
2149                         ostate = ppp->rc_state;
2150                         ppp->rcomp = cp;
2151                         ppp->rc_state = state;
2152                         ppp_recv_unlock(ppp);
2153                         if (ostate) {
2154                                 ocomp->decomp_free(ostate);
2155                                 module_put(ocomp->owner);
2156                         }
2157                         err = 0;
2158                 } else
2159                         module_put(cp->owner);
2160         }
2161
2162  out:
2163         return err;
2164 }
2165
2166 /*
2167  * Look at a CCP packet and update our state accordingly.
2168  * We assume the caller has the xmit or recv path locked.
2169  */
2170 static void
2171 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2172 {
2173         unsigned char *dp;
2174         int len;
2175
2176         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2177                 return; /* no header */
2178         dp = skb->data + 2;
2179
2180         switch (CCP_CODE(dp)) {
2181         case CCP_CONFREQ:
2182
2183                 /* A ConfReq starts negotiation of compression
2184                  * in one direction of transmission,
2185                  * and hence brings it down...but which way?
2186                  *
2187                  * Remember:
2188                  * A ConfReq indicates what the sender would like to receive
2189                  */
2190                 if(inbound)
2191                         /* He is proposing what I should send */
2192                         ppp->xstate &= ~SC_COMP_RUN;
2193                 else
2194                         /* I am proposing to what he should send */
2195                         ppp->rstate &= ~SC_DECOMP_RUN;
2196
2197                 break;
2198
2199         case CCP_TERMREQ:
2200         case CCP_TERMACK:
2201                 /*
2202                  * CCP is going down, both directions of transmission
2203                  */
2204                 ppp->rstate &= ~SC_DECOMP_RUN;
2205                 ppp->xstate &= ~SC_COMP_RUN;
2206                 break;
2207
2208         case CCP_CONFACK:
2209                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2210                         break;
2211                 len = CCP_LENGTH(dp);
2212                 if (!pskb_may_pull(skb, len + 2))
2213                         return;         /* too short */
2214                 dp += CCP_HDRLEN;
2215                 len -= CCP_HDRLEN;
2216                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2217                         break;
2218                 if (inbound) {
2219                         /* we will start receiving compressed packets */
2220                         if (!ppp->rc_state)
2221                                 break;
2222                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2223                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2224                                 ppp->rstate |= SC_DECOMP_RUN;
2225                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2226                         }
2227                 } else {
2228                         /* we will soon start sending compressed packets */
2229                         if (!ppp->xc_state)
2230                                 break;
2231                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2232                                         ppp->file.index, 0, ppp->debug))
2233                                 ppp->xstate |= SC_COMP_RUN;
2234                 }
2235                 break;
2236
2237         case CCP_RESETACK:
2238                 /* reset the [de]compressor */
2239                 if ((ppp->flags & SC_CCP_UP) == 0)
2240                         break;
2241                 if (inbound) {
2242                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2243                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2244                                 ppp->rstate &= ~SC_DC_ERROR;
2245                         }
2246                 } else {
2247                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2248                                 ppp->xcomp->comp_reset(ppp->xc_state);
2249                 }
2250                 break;
2251         }
2252 }
2253
2254 /* Free up compression resources. */
2255 static void
2256 ppp_ccp_closed(struct ppp *ppp)
2257 {
2258         void *xstate, *rstate;
2259         struct compressor *xcomp, *rcomp;
2260
2261         ppp_lock(ppp);
2262         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2263         ppp->xstate = 0;
2264         xcomp = ppp->xcomp;
2265         xstate = ppp->xc_state;
2266         ppp->xc_state = NULL;
2267         ppp->rstate = 0;
2268         rcomp = ppp->rcomp;
2269         rstate = ppp->rc_state;
2270         ppp->rc_state = NULL;
2271         ppp_unlock(ppp);
2272
2273         if (xstate) {
2274                 xcomp->comp_free(xstate);
2275                 module_put(xcomp->owner);
2276         }
2277         if (rstate) {
2278                 rcomp->decomp_free(rstate);
2279                 module_put(rcomp->owner);
2280         }
2281 }
2282
2283 /* List of compressors. */
2284 static LIST_HEAD(compressor_list);
2285 static DEFINE_SPINLOCK(compressor_list_lock);
2286
2287 struct compressor_entry {
2288         struct list_head list;
2289         struct compressor *comp;
2290 };
2291
2292 static struct compressor_entry *
2293 find_comp_entry(int proto)
2294 {
2295         struct compressor_entry *ce;
2296
2297         list_for_each_entry(ce, &compressor_list, list) {
2298                 if (ce->comp->compress_proto == proto)
2299                         return ce;
2300         }
2301         return NULL;
2302 }
2303
2304 /* Register a compressor */
2305 int
2306 ppp_register_compressor(struct compressor *cp)
2307 {
2308         struct compressor_entry *ce;
2309         int ret;
2310         spin_lock(&compressor_list_lock);
2311         ret = -EEXIST;
2312         if (find_comp_entry(cp->compress_proto))
2313                 goto out;
2314         ret = -ENOMEM;
2315         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2316         if (!ce)
2317                 goto out;
2318         ret = 0;
2319         ce->comp = cp;
2320         list_add(&ce->list, &compressor_list);
2321  out:
2322         spin_unlock(&compressor_list_lock);
2323         return ret;
2324 }
2325
2326 /* Unregister a compressor */
2327 void
2328 ppp_unregister_compressor(struct compressor *cp)
2329 {
2330         struct compressor_entry *ce;
2331
2332         spin_lock(&compressor_list_lock);
2333         ce = find_comp_entry(cp->compress_proto);
2334         if (ce && ce->comp == cp) {
2335                 list_del(&ce->list);
2336                 kfree(ce);
2337         }
2338         spin_unlock(&compressor_list_lock);
2339 }
2340
2341 /* Find a compressor. */
2342 static struct compressor *
2343 find_compressor(int type)
2344 {
2345         struct compressor_entry *ce;
2346         struct compressor *cp = NULL;
2347
2348         spin_lock(&compressor_list_lock);
2349         ce = find_comp_entry(type);
2350         if (ce) {
2351                 cp = ce->comp;
2352                 if (!try_module_get(cp->owner))
2353                         cp = NULL;
2354         }
2355         spin_unlock(&compressor_list_lock);
2356         return cp;
2357 }
2358
2359 /*
2360  * Miscelleneous stuff.
2361  */
2362
2363 static void
2364 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2365 {
2366         struct slcompress *vj = ppp->vj;
2367
2368         memset(st, 0, sizeof(*st));
2369         st->p.ppp_ipackets = ppp->dev->stats.rx_packets;
2370         st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2371         st->p.ppp_ibytes = ppp->dev->stats.rx_bytes;
2372         st->p.ppp_opackets = ppp->dev->stats.tx_packets;
2373         st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2374         st->p.ppp_obytes = ppp->dev->stats.tx_bytes;
2375         if (!vj)
2376                 return;
2377         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2378         st->vj.vjs_compressed = vj->sls_o_compressed;
2379         st->vj.vjs_searches = vj->sls_o_searches;
2380         st->vj.vjs_misses = vj->sls_o_misses;
2381         st->vj.vjs_errorin = vj->sls_i_error;
2382         st->vj.vjs_tossed = vj->sls_i_tossed;
2383         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2384         st->vj.vjs_compressedin = vj->sls_i_compressed;
2385 }
2386
2387 /*
2388  * Stuff for handling the lists of ppp units and channels
2389  * and for initialization.
2390  */
2391
2392 /*
2393  * Create a new ppp interface unit.  Fails if it can't allocate memory
2394  * or if there is already a unit with the requested number.
2395  * unit == -1 means allocate a new number.
2396  */
2397 static struct ppp *
2398 ppp_create_interface(int unit, int *retp)
2399 {
2400         struct ppp *ppp;
2401         struct net_device *dev = NULL;
2402         int ret = -ENOMEM;
2403         int i;
2404
2405         dev = alloc_netdev(sizeof(struct ppp), "", ppp_setup);
2406         if (!dev)
2407                 goto out1;
2408
2409         ppp = netdev_priv(dev);
2410         ppp->dev = dev;
2411         ppp->mru = PPP_MRU;
2412         init_ppp_file(&ppp->file, INTERFACE);
2413         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2414         for (i = 0; i < NUM_NP; ++i)
2415                 ppp->npmode[i] = NPMODE_PASS;
2416         INIT_LIST_HEAD(&ppp->channels);
2417         spin_lock_init(&ppp->rlock);
2418         spin_lock_init(&ppp->wlock);
2419 #ifdef CONFIG_PPP_MULTILINK
2420         ppp->minseq = -1;
2421         skb_queue_head_init(&ppp->mrq);
2422 #endif /* CONFIG_PPP_MULTILINK */
2423
2424         ret = -EEXIST;
2425         mutex_lock(&all_ppp_mutex);
2426
2427         if (unit < 0) {
2428                 unit = unit_get(&ppp_units_idr, ppp);
2429                 if (unit < 0) {
2430                         *retp = unit;
2431                         goto out2;
2432                 }
2433         } else {
2434                 if (unit_find(&ppp_units_idr, unit))
2435                         goto out2; /* unit already exists */
2436                 /*
2437                  * if caller need a specified unit number
2438                  * lets try to satisfy him, otherwise --
2439                  * he should better ask us for new unit number
2440                  *
2441                  * NOTE: yes I know that returning EEXIST it's not
2442                  * fair but at least pppd will ask us to allocate
2443                  * new unit in this case so user is happy :)
2444                  */
2445                 unit = unit_set(&ppp_units_idr, ppp, unit);
2446                 if (unit < 0)
2447                         goto out2;
2448         }
2449
2450         /* Initialize the new ppp unit */
2451         ppp->file.index = unit;
2452         sprintf(dev->name, "ppp%d", unit);
2453
2454         ret = register_netdev(dev);
2455         if (ret != 0) {
2456                 unit_put(&ppp_units_idr, unit);
2457                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2458                        dev->name, ret);
2459                 goto out2;
2460         }
2461
2462         atomic_inc(&ppp_unit_count);
2463         mutex_unlock(&all_ppp_mutex);
2464
2465         *retp = 0;
2466         return ppp;
2467
2468 out2:
2469         mutex_unlock(&all_ppp_mutex);
2470         free_netdev(dev);
2471 out1:
2472         *retp = ret;
2473         return NULL;
2474 }
2475
2476 /*
2477  * Initialize a ppp_file structure.
2478  */
2479 static void
2480 init_ppp_file(struct ppp_file *pf, int kind)
2481 {
2482         pf->kind = kind;
2483         skb_queue_head_init(&pf->xq);
2484         skb_queue_head_init(&pf->rq);
2485         atomic_set(&pf->refcnt, 1);
2486         init_waitqueue_head(&pf->rwait);
2487 }
2488
2489 /*
2490  * Take down a ppp interface unit - called when the owning file
2491  * (the one that created the unit) is closed or detached.
2492  */
2493 static void ppp_shutdown_interface(struct ppp *ppp)
2494 {
2495         mutex_lock(&all_ppp_mutex);
2496         /* This will call dev_close() for us. */
2497         ppp_lock(ppp);
2498         if (!ppp->closing) {
2499                 ppp->closing = 1;
2500                 ppp_unlock(ppp);
2501                 unregister_netdev(ppp->dev);
2502         } else
2503                 ppp_unlock(ppp);
2504
2505         unit_put(&ppp_units_idr, ppp->file.index);
2506         ppp->file.dead = 1;
2507         ppp->owner = NULL;
2508         wake_up_interruptible(&ppp->file.rwait);
2509         mutex_unlock(&all_ppp_mutex);
2510 }
2511
2512 /*
2513  * Free the memory used by a ppp unit.  This is only called once
2514  * there are no channels connected to the unit and no file structs
2515  * that reference the unit.
2516  */
2517 static void ppp_destroy_interface(struct ppp *ppp)
2518 {
2519         atomic_dec(&ppp_unit_count);
2520
2521         if (!ppp->file.dead || ppp->n_channels) {
2522                 /* "can't happen" */
2523                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2524                        "n_channels=%d !\n", ppp, ppp->file.dead,
2525                        ppp->n_channels);
2526                 return;
2527         }
2528
2529         ppp_ccp_closed(ppp);
2530         if (ppp->vj) {
2531                 slhc_free(ppp->vj);
2532                 ppp->vj = NULL;
2533         }
2534         skb_queue_purge(&ppp->file.xq);
2535         skb_queue_purge(&ppp->file.rq);
2536 #ifdef CONFIG_PPP_MULTILINK
2537         skb_queue_purge(&ppp->mrq);
2538 #endif /* CONFIG_PPP_MULTILINK */
2539 #ifdef CONFIG_PPP_FILTER
2540         kfree(ppp->pass_filter);
2541         ppp->pass_filter = NULL;
2542         kfree(ppp->active_filter);
2543         ppp->active_filter = NULL;
2544 #endif /* CONFIG_PPP_FILTER */
2545
2546         if (ppp->xmit_pending)
2547                 kfree_skb(ppp->xmit_pending);
2548
2549         free_netdev(ppp->dev);
2550 }
2551
2552 /*
2553  * Locate an existing ppp unit.
2554  * The caller should have locked the all_ppp_mutex.
2555  */
2556 static struct ppp *
2557 ppp_find_unit(int unit)
2558 {
2559         return unit_find(&ppp_units_idr, unit);
2560 }
2561
2562 /*
2563  * Locate an existing ppp channel.
2564  * The caller should have locked the all_channels_lock.
2565  * First we look in the new_channels list, then in the
2566  * all_channels list.  If found in the new_channels list,
2567  * we move it to the all_channels list.  This is for speed
2568  * when we have a lot of channels in use.
2569  */
2570 static struct channel *
2571 ppp_find_channel(int unit)
2572 {
2573         struct channel *pch;
2574
2575         list_for_each_entry(pch, &new_channels, list) {
2576                 if (pch->file.index == unit) {
2577                         list_move(&pch->list, &all_channels);
2578                         return pch;
2579                 }
2580         }
2581         list_for_each_entry(pch, &all_channels, list) {
2582                 if (pch->file.index == unit)
2583                         return pch;
2584         }
2585         return NULL;
2586 }
2587
2588 /*
2589  * Connect a PPP channel to a PPP interface unit.
2590  */
2591 static int
2592 ppp_connect_channel(struct channel *pch, int unit)
2593 {
2594         struct ppp *ppp;
2595         int ret = -ENXIO;
2596         int hdrlen;
2597
2598         mutex_lock(&all_ppp_mutex);
2599         ppp = ppp_find_unit(unit);
2600         if (!ppp)
2601                 goto out;
2602         write_lock_bh(&pch->upl);
2603         ret = -EINVAL;
2604         if (pch->ppp)
2605                 goto outl;
2606
2607         ppp_lock(ppp);
2608         if (pch->file.hdrlen > ppp->file.hdrlen)
2609                 ppp->file.hdrlen = pch->file.hdrlen;
2610         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2611         if (hdrlen > ppp->dev->hard_header_len)
2612                 ppp->dev->hard_header_len = hdrlen;
2613         list_add_tail(&pch->clist, &ppp->channels);
2614         ++ppp->n_channels;
2615         pch->ppp = ppp;
2616         atomic_inc(&ppp->file.refcnt);
2617         ppp_unlock(ppp);
2618         ret = 0;
2619
2620  outl:
2621         write_unlock_bh(&pch->upl);
2622  out:
2623         mutex_unlock(&all_ppp_mutex);
2624         return ret;
2625 }
2626
2627 /*
2628  * Disconnect a channel from its ppp unit.
2629  */
2630 static int
2631 ppp_disconnect_channel(struct channel *pch)
2632 {
2633         struct ppp *ppp;
2634         int err = -EINVAL;
2635
2636         write_lock_bh(&pch->upl);
2637         ppp = pch->ppp;
2638         pch->ppp = NULL;
2639         write_unlock_bh(&pch->upl);
2640         if (ppp) {
2641                 /* remove it from the ppp unit's list */
2642                 ppp_lock(ppp);
2643                 list_del(&pch->clist);
2644                 if (--ppp->n_channels == 0)
2645                         wake_up_interruptible(&ppp->file.rwait);
2646                 ppp_unlock(ppp);
2647                 if (atomic_dec_and_test(&ppp->file.refcnt))
2648                         ppp_destroy_interface(ppp);
2649                 err = 0;
2650         }
2651         return err;
2652 }
2653
2654 /*
2655  * Free up the resources used by a ppp channel.
2656  */
2657 static void ppp_destroy_channel(struct channel *pch)
2658 {
2659         atomic_dec(&channel_count);
2660
2661         if (!pch->file.dead) {
2662                 /* "can't happen" */
2663                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2664                        pch);
2665                 return;
2666         }
2667         skb_queue_purge(&pch->file.xq);
2668         skb_queue_purge(&pch->file.rq);
2669         kfree(pch);
2670 }
2671
2672 static void __exit ppp_cleanup(void)
2673 {
2674         /* should never happen */
2675         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2676                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2677         unregister_chrdev(PPP_MAJOR, "ppp");
2678         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2679         class_destroy(ppp_class);
2680         idr_destroy(&ppp_units_idr);
2681 }
2682
2683 /*
2684  * Units handling. Caller must protect concurrent access
2685  * by holding all_ppp_mutex
2686  */
2687
2688 /* associate pointer with specified number */
2689 static int unit_set(struct idr *p, void *ptr, int n)
2690 {
2691         int unit, err;
2692
2693 again:
2694         if (!idr_pre_get(p, GFP_KERNEL)) {
2695                 printk(KERN_ERR "PPP: No free memory for idr\n");
2696                 return -ENOMEM;
2697         }
2698
2699         err = idr_get_new_above(p, ptr, n, &unit);
2700         if (err == -EAGAIN)
2701                 goto again;
2702
2703         if (unit != n) {
2704                 idr_remove(p, unit);
2705                 return -EINVAL;
2706         }
2707
2708         return unit;
2709 }
2710
2711 /* get new free unit number and associate pointer with it */
2712 static int unit_get(struct idr *p, void *ptr)
2713 {
2714         int unit, err;
2715
2716 again:
2717         if (!idr_pre_get(p, GFP_KERNEL)) {
2718                 printk(KERN_ERR "PPP: No free memory for idr\n");
2719                 return -ENOMEM;
2720         }
2721
2722         err = idr_get_new_above(p, ptr, 0, &unit);
2723         if (err == -EAGAIN)
2724                 goto again;
2725
2726         return unit;
2727 }
2728
2729 /* put unit number back to a pool */
2730 static void unit_put(struct idr *p, int n)
2731 {
2732         idr_remove(p, n);
2733 }
2734
2735 /* get pointer associated with the number */
2736 static void *unit_find(struct idr *p, int n)
2737 {
2738         return idr_find(p, n);
2739 }
2740
2741 /* Module/initialization stuff */
2742
2743 module_init(ppp_init);
2744 module_exit(ppp_cleanup);
2745
2746 EXPORT_SYMBOL(ppp_register_channel);
2747 EXPORT_SYMBOL(ppp_unregister_channel);
2748 EXPORT_SYMBOL(ppp_channel_index);
2749 EXPORT_SYMBOL(ppp_unit_number);
2750 EXPORT_SYMBOL(ppp_input);
2751 EXPORT_SYMBOL(ppp_input_error);
2752 EXPORT_SYMBOL(ppp_output_wakeup);
2753 EXPORT_SYMBOL(ppp_register_compressor);
2754 EXPORT_SYMBOL(ppp_unregister_compressor);
2755 MODULE_LICENSE("GPL");
2756 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2757 MODULE_ALIAS("/dev/ppp");