[PPP]: remove redundant NULL pointer checks before kfree & vfree
[linux-2.6.git] / drivers / net / ppp_generic.c
1 /*
2  * Generic PPP layer for Linux.
3  *
4  * Copyright 1999-2002 Paul Mackerras.
5  *
6  *  This program is free software; you can redistribute it and/or
7  *  modify it under the terms of the GNU General Public License
8  *  as published by the Free Software Foundation; either version
9  *  2 of the License, or (at your option) any later version.
10  *
11  * The generic PPP layer handles the PPP network interfaces, the
12  * /dev/ppp device, packet and VJ compression, and multilink.
13  * It talks to PPP `channels' via the interface defined in
14  * include/linux/ppp_channel.h.  Channels provide the basic means for
15  * sending and receiving PPP frames on some kind of communications
16  * channel.
17  *
18  * Part of the code in this driver was inspired by the old async-only
19  * PPP driver, written by Michael Callahan and Al Longyear, and
20  * subsequently hacked by Paul Mackerras.
21  *
22  * ==FILEVERSION 20041108==
23  */
24
25 #include <linux/config.h>
26 #include <linux/module.h>
27 #include <linux/kernel.h>
28 #include <linux/kmod.h>
29 #include <linux/init.h>
30 #include <linux/list.h>
31 #include <linux/devfs_fs_kernel.h>
32 #include <linux/netdevice.h>
33 #include <linux/poll.h>
34 #include <linux/ppp_defs.h>
35 #include <linux/filter.h>
36 #include <linux/if_ppp.h>
37 #include <linux/ppp_channel.h>
38 #include <linux/ppp-comp.h>
39 #include <linux/skbuff.h>
40 #include <linux/rtnetlink.h>
41 #include <linux/if_arp.h>
42 #include <linux/ip.h>
43 #include <linux/tcp.h>
44 #include <linux/spinlock.h>
45 #include <linux/smp_lock.h>
46 #include <linux/rwsem.h>
47 #include <linux/stddef.h>
48 #include <linux/device.h>
49 #include <net/slhc_vj.h>
50 #include <asm/atomic.h>
51
52 #define PPP_VERSION     "2.4.2"
53
54 /*
55  * Network protocols we support.
56  */
57 #define NP_IP   0               /* Internet Protocol V4 */
58 #define NP_IPV6 1               /* Internet Protocol V6 */
59 #define NP_IPX  2               /* IPX protocol */
60 #define NP_AT   3               /* Appletalk protocol */
61 #define NP_MPLS_UC 4            /* MPLS unicast */
62 #define NP_MPLS_MC 5            /* MPLS multicast */
63 #define NUM_NP  6               /* Number of NPs. */
64
65 #define MPHDRLEN        6       /* multilink protocol header length */
66 #define MPHDRLEN_SSN    4       /* ditto with short sequence numbers */
67 #define MIN_FRAG_SIZE   64
68
69 /*
70  * An instance of /dev/ppp can be associated with either a ppp
71  * interface unit or a ppp channel.  In both cases, file->private_data
72  * points to one of these.
73  */
74 struct ppp_file {
75         enum {
76                 INTERFACE=1, CHANNEL
77         }               kind;
78         struct sk_buff_head xq;         /* pppd transmit queue */
79         struct sk_buff_head rq;         /* receive queue for pppd */
80         wait_queue_head_t rwait;        /* for poll on reading /dev/ppp */
81         atomic_t        refcnt;         /* # refs (incl /dev/ppp attached) */
82         int             hdrlen;         /* space to leave for headers */
83         int             index;          /* interface unit / channel number */
84         int             dead;           /* unit/channel has been shut down */
85 };
86
87 #define PF_TO_X(pf, X)          ((X *)((char *)(pf) - offsetof(X, file)))
88
89 #define PF_TO_PPP(pf)           PF_TO_X(pf, struct ppp)
90 #define PF_TO_CHANNEL(pf)       PF_TO_X(pf, struct channel)
91
92 #define ROUNDUP(n, x)           (((n) + (x) - 1) / (x))
93
94 /*
95  * Data structure describing one ppp unit.
96  * A ppp unit corresponds to a ppp network interface device
97  * and represents a multilink bundle.
98  * It can have 0 or more ppp channels connected to it.
99  */
100 struct ppp {
101         struct ppp_file file;           /* stuff for read/write/poll 0 */
102         struct file     *owner;         /* file that owns this unit 48 */
103         struct list_head channels;      /* list of attached channels 4c */
104         int             n_channels;     /* how many channels are attached 54 */
105         spinlock_t      rlock;          /* lock for receive side 58 */
106         spinlock_t      wlock;          /* lock for transmit side 5c */
107         int             mru;            /* max receive unit 60 */
108         unsigned int    flags;          /* control bits 64 */
109         unsigned int    xstate;         /* transmit state bits 68 */
110         unsigned int    rstate;         /* receive state bits 6c */
111         int             debug;          /* debug flags 70 */
112         struct slcompress *vj;          /* state for VJ header compression */
113         enum NPmode     npmode[NUM_NP]; /* what to do with each net proto 78 */
114         struct sk_buff  *xmit_pending;  /* a packet ready to go out 88 */
115         struct compressor *xcomp;       /* transmit packet compressor 8c */
116         void            *xc_state;      /* its internal state 90 */
117         struct compressor *rcomp;       /* receive decompressor 94 */
118         void            *rc_state;      /* its internal state 98 */
119         unsigned long   last_xmit;      /* jiffies when last pkt sent 9c */
120         unsigned long   last_recv;      /* jiffies when last pkt rcvd a0 */
121         struct net_device *dev;         /* network interface device a4 */
122 #ifdef CONFIG_PPP_MULTILINK
123         int             nxchan;         /* next channel to send something on */
124         u32             nxseq;          /* next sequence number to send */
125         int             mrru;           /* MP: max reconst. receive unit */
126         u32             nextseq;        /* MP: seq no of next packet */
127         u32             minseq;         /* MP: min of most recent seqnos */
128         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
129 #endif /* CONFIG_PPP_MULTILINK */
130         struct net_device_stats stats;  /* statistics */
131 #ifdef CONFIG_PPP_FILTER
132         struct sock_filter *pass_filter;        /* filter for packets to pass */
133         struct sock_filter *active_filter;/* filter for pkts to reset idle */
134         unsigned pass_len, active_len;
135 #endif /* CONFIG_PPP_FILTER */
136 };
137
138 /*
139  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
140  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP.
141  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
142  * Bits in xstate: SC_COMP_RUN
143  */
144 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
145                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
146                          |SC_COMP_TCP|SC_REJ_COMP_TCP)
147
148 /*
149  * Private data structure for each channel.
150  * This includes the data structure used for multilink.
151  */
152 struct channel {
153         struct ppp_file file;           /* stuff for read/write/poll */
154         struct list_head list;          /* link in all/new_channels list */
155         struct ppp_channel *chan;       /* public channel data structure */
156         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
157         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
158         struct ppp      *ppp;           /* ppp unit we're connected to */
159         struct list_head clist;         /* link in list of channels per unit */
160         rwlock_t        upl;            /* protects `ppp' */
161 #ifdef CONFIG_PPP_MULTILINK
162         u8              avail;          /* flag used in multilink stuff */
163         u8              had_frag;       /* >= 1 fragments have been sent */
164         u32             lastseq;        /* MP: last sequence # received */
165 #endif /* CONFIG_PPP_MULTILINK */
166 };
167
168 /*
169  * SMP locking issues:
170  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
171  * list and the ppp.n_channels field, you need to take both locks
172  * before you modify them.
173  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
174  * channel.downl.
175  */
176
177 /*
178  * A cardmap represents a mapping from unsigned integers to pointers,
179  * and provides a fast "find lowest unused number" operation.
180  * It uses a broad (32-way) tree with a bitmap at each level.
181  * It is designed to be space-efficient for small numbers of entries
182  * and time-efficient for large numbers of entries.
183  */
184 #define CARDMAP_ORDER   5
185 #define CARDMAP_WIDTH   (1U << CARDMAP_ORDER)
186 #define CARDMAP_MASK    (CARDMAP_WIDTH - 1)
187
188 struct cardmap {
189         int shift;
190         unsigned long inuse;
191         struct cardmap *parent;
192         void *ptr[CARDMAP_WIDTH];
193 };
194 static void *cardmap_get(struct cardmap *map, unsigned int nr);
195 static void cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
196 static unsigned int cardmap_find_first_free(struct cardmap *map);
197 static void cardmap_destroy(struct cardmap **map);
198
199 /*
200  * all_ppp_sem protects the all_ppp_units mapping.
201  * It also ensures that finding a ppp unit in the all_ppp_units map
202  * and updating its file.refcnt field is atomic.
203  */
204 static DECLARE_MUTEX(all_ppp_sem);
205 static struct cardmap *all_ppp_units;
206 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
207
208 /*
209  * all_channels_lock protects all_channels and last_channel_index,
210  * and the atomicity of find a channel and updating its file.refcnt
211  * field.
212  */
213 static DEFINE_SPINLOCK(all_channels_lock);
214 static LIST_HEAD(all_channels);
215 static LIST_HEAD(new_channels);
216 static int last_channel_index;
217 static atomic_t channel_count = ATOMIC_INIT(0);
218
219 /* Get the PPP protocol number from a skb */
220 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
221
222 /* We limit the length of ppp->file.rq to this (arbitrary) value */
223 #define PPP_MAX_RQLEN   32
224
225 /*
226  * Maximum number of multilink fragments queued up.
227  * This has to be large enough to cope with the maximum latency of
228  * the slowest channel relative to the others.  Strictly it should
229  * depend on the number of channels and their characteristics.
230  */
231 #define PPP_MP_MAX_QLEN 128
232
233 /* Multilink header bits. */
234 #define B       0x80            /* this fragment begins a packet */
235 #define E       0x40            /* this fragment ends a packet */
236
237 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
238 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
239 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
240
241 /* Prototypes. */
242 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
243                                 unsigned int cmd, unsigned long arg);
244 static void ppp_xmit_process(struct ppp *ppp);
245 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
246 static void ppp_push(struct ppp *ppp);
247 static void ppp_channel_push(struct channel *pch);
248 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
249                               struct channel *pch);
250 static void ppp_receive_error(struct ppp *ppp);
251 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
252 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
253                                             struct sk_buff *skb);
254 #ifdef CONFIG_PPP_MULTILINK
255 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
256                                 struct channel *pch);
257 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
258 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
259 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
260 #endif /* CONFIG_PPP_MULTILINK */
261 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
262 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
263 static void ppp_ccp_closed(struct ppp *ppp);
264 static struct compressor *find_compressor(int type);
265 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
266 static struct ppp *ppp_create_interface(int unit, int *retp);
267 static void init_ppp_file(struct ppp_file *pf, int kind);
268 static void ppp_shutdown_interface(struct ppp *ppp);
269 static void ppp_destroy_interface(struct ppp *ppp);
270 static struct ppp *ppp_find_unit(int unit);
271 static struct channel *ppp_find_channel(int unit);
272 static int ppp_connect_channel(struct channel *pch, int unit);
273 static int ppp_disconnect_channel(struct channel *pch);
274 static void ppp_destroy_channel(struct channel *pch);
275
276 static struct class_simple *ppp_class;
277
278 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
279 static inline int proto_to_npindex(int proto)
280 {
281         switch (proto) {
282         case PPP_IP:
283                 return NP_IP;
284         case PPP_IPV6:
285                 return NP_IPV6;
286         case PPP_IPX:
287                 return NP_IPX;
288         case PPP_AT:
289                 return NP_AT;
290         case PPP_MPLS_UC:
291                 return NP_MPLS_UC;
292         case PPP_MPLS_MC:
293                 return NP_MPLS_MC;
294         }
295         return -EINVAL;
296 }
297
298 /* Translates an NP index into a PPP protocol number */
299 static const int npindex_to_proto[NUM_NP] = {
300         PPP_IP,
301         PPP_IPV6,
302         PPP_IPX,
303         PPP_AT,
304         PPP_MPLS_UC,
305         PPP_MPLS_MC,
306 };
307         
308 /* Translates an ethertype into an NP index */
309 static inline int ethertype_to_npindex(int ethertype)
310 {
311         switch (ethertype) {
312         case ETH_P_IP:
313                 return NP_IP;
314         case ETH_P_IPV6:
315                 return NP_IPV6;
316         case ETH_P_IPX:
317                 return NP_IPX;
318         case ETH_P_PPPTALK:
319         case ETH_P_ATALK:
320                 return NP_AT;
321         case ETH_P_MPLS_UC:
322                 return NP_MPLS_UC;
323         case ETH_P_MPLS_MC:
324                 return NP_MPLS_MC;
325         }
326         return -1;
327 }
328
329 /* Translates an NP index into an ethertype */
330 static const int npindex_to_ethertype[NUM_NP] = {
331         ETH_P_IP,
332         ETH_P_IPV6,
333         ETH_P_IPX,
334         ETH_P_PPPTALK,
335         ETH_P_MPLS_UC,
336         ETH_P_MPLS_MC,
337 };
338
339 /*
340  * Locking shorthand.
341  */
342 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
343 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
344 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
345 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
346 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
347                                      ppp_recv_lock(ppp); } while (0)
348 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
349                                      ppp_xmit_unlock(ppp); } while (0)
350
351 /*
352  * /dev/ppp device routines.
353  * The /dev/ppp device is used by pppd to control the ppp unit.
354  * It supports the read, write, ioctl and poll functions.
355  * Open instances of /dev/ppp can be in one of three states:
356  * unattached, attached to a ppp unit, or attached to a ppp channel.
357  */
358 static int ppp_open(struct inode *inode, struct file *file)
359 {
360         /*
361          * This could (should?) be enforced by the permissions on /dev/ppp.
362          */
363         if (!capable(CAP_NET_ADMIN))
364                 return -EPERM;
365         return 0;
366 }
367
368 static int ppp_release(struct inode *inode, struct file *file)
369 {
370         struct ppp_file *pf = file->private_data;
371         struct ppp *ppp;
372
373         if (pf != 0) {
374                 file->private_data = NULL;
375                 if (pf->kind == INTERFACE) {
376                         ppp = PF_TO_PPP(pf);
377                         if (file == ppp->owner)
378                                 ppp_shutdown_interface(ppp);
379                 }
380                 if (atomic_dec_and_test(&pf->refcnt)) {
381                         switch (pf->kind) {
382                         case INTERFACE:
383                                 ppp_destroy_interface(PF_TO_PPP(pf));
384                                 break;
385                         case CHANNEL:
386                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
387                                 break;
388                         }
389                 }
390         }
391         return 0;
392 }
393
394 static ssize_t ppp_read(struct file *file, char __user *buf,
395                         size_t count, loff_t *ppos)
396 {
397         struct ppp_file *pf = file->private_data;
398         DECLARE_WAITQUEUE(wait, current);
399         ssize_t ret;
400         struct sk_buff *skb = NULL;
401
402         ret = count;
403
404         if (pf == 0)
405                 return -ENXIO;
406         add_wait_queue(&pf->rwait, &wait);
407         for (;;) {
408                 set_current_state(TASK_INTERRUPTIBLE);
409                 skb = skb_dequeue(&pf->rq);
410                 if (skb)
411                         break;
412                 ret = 0;
413                 if (pf->dead)
414                         break;
415                 if (pf->kind == INTERFACE) {
416                         /*
417                          * Return 0 (EOF) on an interface that has no
418                          * channels connected, unless it is looping
419                          * network traffic (demand mode).
420                          */
421                         struct ppp *ppp = PF_TO_PPP(pf);
422                         if (ppp->n_channels == 0
423                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
424                                 break;
425                 }
426                 ret = -EAGAIN;
427                 if (file->f_flags & O_NONBLOCK)
428                         break;
429                 ret = -ERESTARTSYS;
430                 if (signal_pending(current))
431                         break;
432                 schedule();
433         }
434         set_current_state(TASK_RUNNING);
435         remove_wait_queue(&pf->rwait, &wait);
436
437         if (skb == 0)
438                 goto out;
439
440         ret = -EOVERFLOW;
441         if (skb->len > count)
442                 goto outf;
443         ret = -EFAULT;
444         if (copy_to_user(buf, skb->data, skb->len))
445                 goto outf;
446         ret = skb->len;
447
448  outf:
449         kfree_skb(skb);
450  out:
451         return ret;
452 }
453
454 static ssize_t ppp_write(struct file *file, const char __user *buf,
455                          size_t count, loff_t *ppos)
456 {
457         struct ppp_file *pf = file->private_data;
458         struct sk_buff *skb;
459         ssize_t ret;
460
461         if (pf == 0)
462                 return -ENXIO;
463         ret = -ENOMEM;
464         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
465         if (skb == 0)
466                 goto out;
467         skb_reserve(skb, pf->hdrlen);
468         ret = -EFAULT;
469         if (copy_from_user(skb_put(skb, count), buf, count)) {
470                 kfree_skb(skb);
471                 goto out;
472         }
473
474         skb_queue_tail(&pf->xq, skb);
475
476         switch (pf->kind) {
477         case INTERFACE:
478                 ppp_xmit_process(PF_TO_PPP(pf));
479                 break;
480         case CHANNEL:
481                 ppp_channel_push(PF_TO_CHANNEL(pf));
482                 break;
483         }
484
485         ret = count;
486
487  out:
488         return ret;
489 }
490
491 /* No kernel lock - fine */
492 static unsigned int ppp_poll(struct file *file, poll_table *wait)
493 {
494         struct ppp_file *pf = file->private_data;
495         unsigned int mask;
496
497         if (pf == 0)
498                 return 0;
499         poll_wait(file, &pf->rwait, wait);
500         mask = POLLOUT | POLLWRNORM;
501         if (skb_peek(&pf->rq) != 0)
502                 mask |= POLLIN | POLLRDNORM;
503         if (pf->dead)
504                 mask |= POLLHUP;
505         else if (pf->kind == INTERFACE) {
506                 /* see comment in ppp_read */
507                 struct ppp *ppp = PF_TO_PPP(pf);
508                 if (ppp->n_channels == 0
509                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
510                         mask |= POLLIN | POLLRDNORM;
511         }
512
513         return mask;
514 }
515
516 #ifdef CONFIG_PPP_FILTER
517 static int get_filter(void __user *arg, struct sock_filter **p)
518 {
519         struct sock_fprog uprog;
520         struct sock_filter *code = NULL;
521         int len, err;
522
523         if (copy_from_user(&uprog, arg, sizeof(uprog)))
524                 return -EFAULT;
525
526         if (uprog.len > BPF_MAXINSNS)
527                 return -EINVAL;
528
529         if (!uprog.len) {
530                 *p = NULL;
531                 return 0;
532         }
533
534         len = uprog.len * sizeof(struct sock_filter);
535         code = kmalloc(len, GFP_KERNEL);
536         if (code == NULL)
537                 return -ENOMEM;
538
539         if (copy_from_user(code, uprog.filter, len)) {
540                 kfree(code);
541                 return -EFAULT;
542         }
543
544         err = sk_chk_filter(code, uprog.len);
545         if (err) {
546                 kfree(code);
547                 return err;
548         }
549
550         *p = code;
551         return uprog.len;
552 }
553 #endif /* CONFIG_PPP_FILTER */
554
555 static int ppp_ioctl(struct inode *inode, struct file *file,
556                      unsigned int cmd, unsigned long arg)
557 {
558         struct ppp_file *pf = file->private_data;
559         struct ppp *ppp;
560         int err = -EFAULT, val, val2, i;
561         struct ppp_idle idle;
562         struct npioctl npi;
563         int unit, cflags;
564         struct slcompress *vj;
565         void __user *argp = (void __user *)arg;
566         int __user *p = argp;
567
568         if (pf == 0)
569                 return ppp_unattached_ioctl(pf, file, cmd, arg);
570
571         if (cmd == PPPIOCDETACH) {
572                 /*
573                  * We have to be careful here... if the file descriptor
574                  * has been dup'd, we could have another process in the
575                  * middle of a poll using the same file *, so we had
576                  * better not free the interface data structures -
577                  * instead we fail the ioctl.  Even in this case, we
578                  * shut down the interface if we are the owner of it.
579                  * Actually, we should get rid of PPPIOCDETACH, userland
580                  * (i.e. pppd) could achieve the same effect by closing
581                  * this fd and reopening /dev/ppp.
582                  */
583                 err = -EINVAL;
584                 if (pf->kind == INTERFACE) {
585                         ppp = PF_TO_PPP(pf);
586                         if (file == ppp->owner)
587                                 ppp_shutdown_interface(ppp);
588                 }
589                 if (atomic_read(&file->f_count) <= 2) {
590                         ppp_release(inode, file);
591                         err = 0;
592                 } else
593                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%d\n",
594                                atomic_read(&file->f_count));
595                 return err;
596         }
597
598         if (pf->kind == CHANNEL) {
599                 struct channel *pch = PF_TO_CHANNEL(pf);
600                 struct ppp_channel *chan;
601
602                 switch (cmd) {
603                 case PPPIOCCONNECT:
604                         if (get_user(unit, p))
605                                 break;
606                         err = ppp_connect_channel(pch, unit);
607                         break;
608
609                 case PPPIOCDISCONN:
610                         err = ppp_disconnect_channel(pch);
611                         break;
612
613                 default:
614                         down_read(&pch->chan_sem);
615                         chan = pch->chan;
616                         err = -ENOTTY;
617                         if (chan && chan->ops->ioctl)
618                                 err = chan->ops->ioctl(chan, cmd, arg);
619                         up_read(&pch->chan_sem);
620                 }
621                 return err;
622         }
623
624         if (pf->kind != INTERFACE) {
625                 /* can't happen */
626                 printk(KERN_ERR "PPP: not interface or channel??\n");
627                 return -EINVAL;
628         }
629
630         ppp = PF_TO_PPP(pf);
631         switch (cmd) {
632         case PPPIOCSMRU:
633                 if (get_user(val, p))
634                         break;
635                 ppp->mru = val;
636                 err = 0;
637                 break;
638
639         case PPPIOCSFLAGS:
640                 if (get_user(val, p))
641                         break;
642                 ppp_lock(ppp);
643                 cflags = ppp->flags & ~val;
644                 ppp->flags = val & SC_FLAG_BITS;
645                 ppp_unlock(ppp);
646                 if (cflags & SC_CCP_OPEN)
647                         ppp_ccp_closed(ppp);
648                 err = 0;
649                 break;
650
651         case PPPIOCGFLAGS:
652                 val = ppp->flags | ppp->xstate | ppp->rstate;
653                 if (put_user(val, p))
654                         break;
655                 err = 0;
656                 break;
657
658         case PPPIOCSCOMPRESS:
659                 err = ppp_set_compress(ppp, arg);
660                 break;
661
662         case PPPIOCGUNIT:
663                 if (put_user(ppp->file.index, p))
664                         break;
665                 err = 0;
666                 break;
667
668         case PPPIOCSDEBUG:
669                 if (get_user(val, p))
670                         break;
671                 ppp->debug = val;
672                 err = 0;
673                 break;
674
675         case PPPIOCGDEBUG:
676                 if (put_user(ppp->debug, p))
677                         break;
678                 err = 0;
679                 break;
680
681         case PPPIOCGIDLE:
682                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
683                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
684                 if (copy_to_user(argp, &idle, sizeof(idle)))
685                         break;
686                 err = 0;
687                 break;
688
689         case PPPIOCSMAXCID:
690                 if (get_user(val, p))
691                         break;
692                 val2 = 15;
693                 if ((val >> 16) != 0) {
694                         val2 = val >> 16;
695                         val &= 0xffff;
696                 }
697                 vj = slhc_init(val2+1, val+1);
698                 if (vj == 0) {
699                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
700                         err = -ENOMEM;
701                         break;
702                 }
703                 ppp_lock(ppp);
704                 if (ppp->vj != 0)
705                         slhc_free(ppp->vj);
706                 ppp->vj = vj;
707                 ppp_unlock(ppp);
708                 err = 0;
709                 break;
710
711         case PPPIOCGNPMODE:
712         case PPPIOCSNPMODE:
713                 if (copy_from_user(&npi, argp, sizeof(npi)))
714                         break;
715                 err = proto_to_npindex(npi.protocol);
716                 if (err < 0)
717                         break;
718                 i = err;
719                 if (cmd == PPPIOCGNPMODE) {
720                         err = -EFAULT;
721                         npi.mode = ppp->npmode[i];
722                         if (copy_to_user(argp, &npi, sizeof(npi)))
723                                 break;
724                 } else {
725                         ppp->npmode[i] = npi.mode;
726                         /* we may be able to transmit more packets now (??) */
727                         netif_wake_queue(ppp->dev);
728                 }
729                 err = 0;
730                 break;
731
732 #ifdef CONFIG_PPP_FILTER
733         case PPPIOCSPASS:
734         {
735                 struct sock_filter *code;
736                 err = get_filter(argp, &code);
737                 if (err >= 0) {
738                         ppp_lock(ppp);
739                         kfree(ppp->pass_filter);
740                         ppp->pass_filter = code;
741                         ppp->pass_len = err;
742                         ppp_unlock(ppp);
743                         err = 0;
744                 }
745                 break;
746         }
747         case PPPIOCSACTIVE:
748         {
749                 struct sock_filter *code;
750                 err = get_filter(argp, &code);
751                 if (err >= 0) {
752                         ppp_lock(ppp);
753                         kfree(ppp->active_filter);
754                         ppp->active_filter = code;
755                         ppp->active_len = err;
756                         ppp_unlock(ppp);
757                         err = 0;
758                 }
759                 break;
760         }
761 #endif /* CONFIG_PPP_FILTER */
762
763 #ifdef CONFIG_PPP_MULTILINK
764         case PPPIOCSMRRU:
765                 if (get_user(val, p))
766                         break;
767                 ppp_recv_lock(ppp);
768                 ppp->mrru = val;
769                 ppp_recv_unlock(ppp);
770                 err = 0;
771                 break;
772 #endif /* CONFIG_PPP_MULTILINK */
773
774         default:
775                 err = -ENOTTY;
776         }
777
778         return err;
779 }
780
781 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
782                                 unsigned int cmd, unsigned long arg)
783 {
784         int unit, err = -EFAULT;
785         struct ppp *ppp;
786         struct channel *chan;
787         int __user *p = (int __user *)arg;
788
789         switch (cmd) {
790         case PPPIOCNEWUNIT:
791                 /* Create a new ppp unit */
792                 if (get_user(unit, p))
793                         break;
794                 ppp = ppp_create_interface(unit, &err);
795                 if (ppp == 0)
796                         break;
797                 file->private_data = &ppp->file;
798                 ppp->owner = file;
799                 err = -EFAULT;
800                 if (put_user(ppp->file.index, p))
801                         break;
802                 err = 0;
803                 break;
804
805         case PPPIOCATTACH:
806                 /* Attach to an existing ppp unit */
807                 if (get_user(unit, p))
808                         break;
809                 down(&all_ppp_sem);
810                 err = -ENXIO;
811                 ppp = ppp_find_unit(unit);
812                 if (ppp != 0) {
813                         atomic_inc(&ppp->file.refcnt);
814                         file->private_data = &ppp->file;
815                         err = 0;
816                 }
817                 up(&all_ppp_sem);
818                 break;
819
820         case PPPIOCATTCHAN:
821                 if (get_user(unit, p))
822                         break;
823                 spin_lock_bh(&all_channels_lock);
824                 err = -ENXIO;
825                 chan = ppp_find_channel(unit);
826                 if (chan != 0) {
827                         atomic_inc(&chan->file.refcnt);
828                         file->private_data = &chan->file;
829                         err = 0;
830                 }
831                 spin_unlock_bh(&all_channels_lock);
832                 break;
833
834         default:
835                 err = -ENOTTY;
836         }
837         return err;
838 }
839
840 static struct file_operations ppp_device_fops = {
841         .owner          = THIS_MODULE,
842         .read           = ppp_read,
843         .write          = ppp_write,
844         .poll           = ppp_poll,
845         .ioctl          = ppp_ioctl,
846         .open           = ppp_open,
847         .release        = ppp_release
848 };
849
850 #define PPP_MAJOR       108
851
852 /* Called at boot time if ppp is compiled into the kernel,
853    or at module load time (from init_module) if compiled as a module. */
854 static int __init ppp_init(void)
855 {
856         int err;
857
858         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
859         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
860         if (!err) {
861                 ppp_class = class_simple_create(THIS_MODULE, "ppp");
862                 if (IS_ERR(ppp_class)) {
863                         err = PTR_ERR(ppp_class);
864                         goto out_chrdev;
865                 }
866                 class_simple_device_add(ppp_class, MKDEV(PPP_MAJOR, 0), NULL, "ppp");
867                 err = devfs_mk_cdev(MKDEV(PPP_MAJOR, 0),
868                                 S_IFCHR|S_IRUSR|S_IWUSR, "ppp");
869                 if (err)
870                         goto out_class;
871         }
872
873 out:
874         if (err)
875                 printk(KERN_ERR "failed to register PPP device (%d)\n", err);
876         return err;
877
878 out_class:
879         class_simple_device_remove(MKDEV(PPP_MAJOR,0));
880         class_simple_destroy(ppp_class);
881 out_chrdev:
882         unregister_chrdev(PPP_MAJOR, "ppp");
883         goto out;
884 }
885
886 /*
887  * Network interface unit routines.
888  */
889 static int
890 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
891 {
892         struct ppp *ppp = (struct ppp *) dev->priv;
893         int npi, proto;
894         unsigned char *pp;
895
896         npi = ethertype_to_npindex(ntohs(skb->protocol));
897         if (npi < 0)
898                 goto outf;
899
900         /* Drop, accept or reject the packet */
901         switch (ppp->npmode[npi]) {
902         case NPMODE_PASS:
903                 break;
904         case NPMODE_QUEUE:
905                 /* it would be nice to have a way to tell the network
906                    system to queue this one up for later. */
907                 goto outf;
908         case NPMODE_DROP:
909         case NPMODE_ERROR:
910                 goto outf;
911         }
912
913         /* Put the 2-byte PPP protocol number on the front,
914            making sure there is room for the address and control fields. */
915         if (skb_headroom(skb) < PPP_HDRLEN) {
916                 struct sk_buff *ns;
917
918                 ns = alloc_skb(skb->len + dev->hard_header_len, GFP_ATOMIC);
919                 if (ns == 0)
920                         goto outf;
921                 skb_reserve(ns, dev->hard_header_len);
922                 skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
923                 kfree_skb(skb);
924                 skb = ns;
925         }
926         pp = skb_push(skb, 2);
927         proto = npindex_to_proto[npi];
928         pp[0] = proto >> 8;
929         pp[1] = proto;
930
931         netif_stop_queue(dev);
932         skb_queue_tail(&ppp->file.xq, skb);
933         ppp_xmit_process(ppp);
934         return 0;
935
936  outf:
937         kfree_skb(skb);
938         ++ppp->stats.tx_dropped;
939         return 0;
940 }
941
942 static struct net_device_stats *
943 ppp_net_stats(struct net_device *dev)
944 {
945         struct ppp *ppp = (struct ppp *) dev->priv;
946
947         return &ppp->stats;
948 }
949
950 static int
951 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
952 {
953         struct ppp *ppp = dev->priv;
954         int err = -EFAULT;
955         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
956         struct ppp_stats stats;
957         struct ppp_comp_stats cstats;
958         char *vers;
959
960         switch (cmd) {
961         case SIOCGPPPSTATS:
962                 ppp_get_stats(ppp, &stats);
963                 if (copy_to_user(addr, &stats, sizeof(stats)))
964                         break;
965                 err = 0;
966                 break;
967
968         case SIOCGPPPCSTATS:
969                 memset(&cstats, 0, sizeof(cstats));
970                 if (ppp->xc_state != 0)
971                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
972                 if (ppp->rc_state != 0)
973                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
974                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
975                         break;
976                 err = 0;
977                 break;
978
979         case SIOCGPPPVER:
980                 vers = PPP_VERSION;
981                 if (copy_to_user(addr, vers, strlen(vers) + 1))
982                         break;
983                 err = 0;
984                 break;
985
986         default:
987                 err = -EINVAL;
988         }
989
990         return err;
991 }
992
993 static void ppp_setup(struct net_device *dev)
994 {
995         dev->hard_header_len = PPP_HDRLEN;
996         dev->mtu = PPP_MTU;
997         dev->addr_len = 0;
998         dev->tx_queue_len = 3;
999         dev->type = ARPHRD_PPP;
1000         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1001 }
1002
1003 /*
1004  * Transmit-side routines.
1005  */
1006
1007 /*
1008  * Called to do any work queued up on the transmit side
1009  * that can now be done.
1010  */
1011 static void
1012 ppp_xmit_process(struct ppp *ppp)
1013 {
1014         struct sk_buff *skb;
1015
1016         ppp_xmit_lock(ppp);
1017         if (ppp->dev != 0) {
1018                 ppp_push(ppp);
1019                 while (ppp->xmit_pending == 0
1020                        && (skb = skb_dequeue(&ppp->file.xq)) != 0)
1021                         ppp_send_frame(ppp, skb);
1022                 /* If there's no work left to do, tell the core net
1023                    code that we can accept some more. */
1024                 if (ppp->xmit_pending == 0 && skb_peek(&ppp->file.xq) == 0)
1025                         netif_wake_queue(ppp->dev);
1026         }
1027         ppp_xmit_unlock(ppp);
1028 }
1029
1030 /*
1031  * Compress and send a frame.
1032  * The caller should have locked the xmit path,
1033  * and xmit_pending should be 0.
1034  */
1035 static void
1036 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1037 {
1038         int proto = PPP_PROTO(skb);
1039         struct sk_buff *new_skb;
1040         int len;
1041         unsigned char *cp;
1042
1043         if (proto < 0x8000) {
1044 #ifdef CONFIG_PPP_FILTER
1045                 /* check if we should pass this packet */
1046                 /* the filter instructions are constructed assuming
1047                    a four-byte PPP header on each packet */
1048                 *skb_push(skb, 2) = 1;
1049                 if (ppp->pass_filter
1050                     && sk_run_filter(skb, ppp->pass_filter,
1051                                      ppp->pass_len) == 0) {
1052                         if (ppp->debug & 1)
1053                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1054                         kfree_skb(skb);
1055                         return;
1056                 }
1057                 /* if this packet passes the active filter, record the time */
1058                 if (!(ppp->active_filter
1059                       && sk_run_filter(skb, ppp->active_filter,
1060                                        ppp->active_len) == 0))
1061                         ppp->last_xmit = jiffies;
1062                 skb_pull(skb, 2);
1063 #else
1064                 /* for data packets, record the time */
1065                 ppp->last_xmit = jiffies;
1066 #endif /* CONFIG_PPP_FILTER */
1067         }
1068
1069         ++ppp->stats.tx_packets;
1070         ppp->stats.tx_bytes += skb->len - 2;
1071
1072         switch (proto) {
1073         case PPP_IP:
1074                 if (ppp->vj == 0 || (ppp->flags & SC_COMP_TCP) == 0)
1075                         break;
1076                 /* try to do VJ TCP header compression */
1077                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1078                                     GFP_ATOMIC);
1079                 if (new_skb == 0) {
1080                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1081                         goto drop;
1082                 }
1083                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1084                 cp = skb->data + 2;
1085                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1086                                     new_skb->data + 2, &cp,
1087                                     !(ppp->flags & SC_NO_TCP_CCID));
1088                 if (cp == skb->data + 2) {
1089                         /* didn't compress */
1090                         kfree_skb(new_skb);
1091                 } else {
1092                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1093                                 proto = PPP_VJC_COMP;
1094                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1095                         } else {
1096                                 proto = PPP_VJC_UNCOMP;
1097                                 cp[0] = skb->data[2];
1098                         }
1099                         kfree_skb(skb);
1100                         skb = new_skb;
1101                         cp = skb_put(skb, len + 2);
1102                         cp[0] = 0;
1103                         cp[1] = proto;
1104                 }
1105                 break;
1106
1107         case PPP_CCP:
1108                 /* peek at outbound CCP frames */
1109                 ppp_ccp_peek(ppp, skb, 0);
1110                 break;
1111         }
1112
1113         /* try to do packet compression */
1114         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0
1115             && proto != PPP_LCP && proto != PPP_CCP) {
1116                 new_skb = alloc_skb(ppp->dev->mtu + ppp->dev->hard_header_len,
1117                                     GFP_ATOMIC);
1118                 if (new_skb == 0) {
1119                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1120                         goto drop;
1121                 }
1122                 if (ppp->dev->hard_header_len > PPP_HDRLEN)
1123                         skb_reserve(new_skb,
1124                                     ppp->dev->hard_header_len - PPP_HDRLEN);
1125
1126                 /* compressor still expects A/C bytes in hdr */
1127                 len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1128                                            new_skb->data, skb->len + 2,
1129                                            ppp->dev->mtu + PPP_HDRLEN);
1130                 if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1131                         kfree_skb(skb);
1132                         skb = new_skb;
1133                         skb_put(skb, len);
1134                         skb_pull(skb, 2);       /* pull off A/C bytes */
1135                 } else {
1136                         /* didn't compress, or CCP not up yet */
1137                         kfree_skb(new_skb);
1138                 }
1139         }
1140
1141         /*
1142          * If we are waiting for traffic (demand dialling),
1143          * queue it up for pppd to receive.
1144          */
1145         if (ppp->flags & SC_LOOP_TRAFFIC) {
1146                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1147                         goto drop;
1148                 skb_queue_tail(&ppp->file.rq, skb);
1149                 wake_up_interruptible(&ppp->file.rwait);
1150                 return;
1151         }
1152
1153         ppp->xmit_pending = skb;
1154         ppp_push(ppp);
1155         return;
1156
1157  drop:
1158         kfree_skb(skb);
1159         ++ppp->stats.tx_errors;
1160 }
1161
1162 /*
1163  * Try to send the frame in xmit_pending.
1164  * The caller should have the xmit path locked.
1165  */
1166 static void
1167 ppp_push(struct ppp *ppp)
1168 {
1169         struct list_head *list;
1170         struct channel *pch;
1171         struct sk_buff *skb = ppp->xmit_pending;
1172
1173         if (skb == 0)
1174                 return;
1175
1176         list = &ppp->channels;
1177         if (list_empty(list)) {
1178                 /* nowhere to send the packet, just drop it */
1179                 ppp->xmit_pending = NULL;
1180                 kfree_skb(skb);
1181                 return;
1182         }
1183
1184         if ((ppp->flags & SC_MULTILINK) == 0) {
1185                 /* not doing multilink: send it down the first channel */
1186                 list = list->next;
1187                 pch = list_entry(list, struct channel, clist);
1188
1189                 spin_lock_bh(&pch->downl);
1190                 if (pch->chan) {
1191                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1192                                 ppp->xmit_pending = NULL;
1193                 } else {
1194                         /* channel got unregistered */
1195                         kfree_skb(skb);
1196                         ppp->xmit_pending = NULL;
1197                 }
1198                 spin_unlock_bh(&pch->downl);
1199                 return;
1200         }
1201
1202 #ifdef CONFIG_PPP_MULTILINK
1203         /* Multilink: fragment the packet over as many links
1204            as can take the packet at the moment. */
1205         if (!ppp_mp_explode(ppp, skb))
1206                 return;
1207 #endif /* CONFIG_PPP_MULTILINK */
1208
1209         ppp->xmit_pending = NULL;
1210         kfree_skb(skb);
1211 }
1212
1213 #ifdef CONFIG_PPP_MULTILINK
1214 /*
1215  * Divide a packet to be transmitted into fragments and
1216  * send them out the individual links.
1217  */
1218 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1219 {
1220         int nch, len, fragsize;
1221         int i, bits, hdrlen, mtu;
1222         int flen, fnb;
1223         unsigned char *p, *q;
1224         struct list_head *list;
1225         struct channel *pch;
1226         struct sk_buff *frag;
1227         struct ppp_channel *chan;
1228
1229         nch = 0;
1230         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1231         list = &ppp->channels;
1232         while ((list = list->next) != &ppp->channels) {
1233                 pch = list_entry(list, struct channel, clist);
1234                 nch += pch->avail = (skb_queue_len(&pch->file.xq) == 0);
1235                 /*
1236                  * If a channel hasn't had a fragment yet, it has to get
1237                  * one before we send any fragments on later channels.
1238                  * If it can't take a fragment now, don't give any
1239                  * to subsequent channels.
1240                  */
1241                 if (!pch->had_frag && !pch->avail) {
1242                         while ((list = list->next) != &ppp->channels) {
1243                                 pch = list_entry(list, struct channel, clist);
1244                                 pch->avail = 0;
1245                         }
1246                         break;
1247                 }
1248         }
1249         if (nch == 0)
1250                 return 0;       /* can't take now, leave it in xmit_pending */
1251
1252         /* Do protocol field compression (XXX this should be optional) */
1253         p = skb->data;
1254         len = skb->len;
1255         if (*p == 0) {
1256                 ++p;
1257                 --len;
1258         }
1259
1260         /* decide on fragment size */
1261         fragsize = len;
1262         if (nch > 1) {
1263                 int maxch = ROUNDUP(len, MIN_FRAG_SIZE);
1264                 if (nch > maxch)
1265                         nch = maxch;
1266                 fragsize = ROUNDUP(fragsize, nch);
1267         }
1268
1269         /* skip to the channel after the one we last used
1270            and start at that one */
1271         for (i = 0; i < ppp->nxchan; ++i) {
1272                 list = list->next;
1273                 if (list == &ppp->channels) {
1274                         i = 0;
1275                         break;
1276                 }
1277         }
1278
1279         /* create a fragment for each channel */
1280         bits = B;
1281         do {
1282                 list = list->next;
1283                 if (list == &ppp->channels) {
1284                         i = 0;
1285                         continue;
1286                 }
1287                 pch = list_entry(list, struct channel, clist);
1288                 ++i;
1289                 if (!pch->avail)
1290                         continue;
1291
1292                 /* check the channel's mtu and whether it is still attached. */
1293                 spin_lock_bh(&pch->downl);
1294                 if (pch->chan == 0 || (mtu = pch->chan->mtu) < hdrlen) {
1295                         /* can't use this channel */
1296                         spin_unlock_bh(&pch->downl);
1297                         pch->avail = 0;
1298                         if (--nch == 0)
1299                                 break;
1300                         continue;
1301                 }
1302
1303                 /*
1304                  * We have to create multiple fragments for this channel
1305                  * if fragsize is greater than the channel's mtu.
1306                  */
1307                 if (fragsize > len)
1308                         fragsize = len;
1309                 for (flen = fragsize; flen > 0; flen -= fnb) {
1310                         fnb = flen;
1311                         if (fnb > mtu + 2 - hdrlen)
1312                                 fnb = mtu + 2 - hdrlen;
1313                         if (fnb >= len)
1314                                 bits |= E;
1315                         frag = alloc_skb(fnb + hdrlen, GFP_ATOMIC);
1316                         if (frag == 0)
1317                                 goto noskb;
1318                         q = skb_put(frag, fnb + hdrlen);
1319                         /* make the MP header */
1320                         q[0] = PPP_MP >> 8;
1321                         q[1] = PPP_MP;
1322                         if (ppp->flags & SC_MP_XSHORTSEQ) {
1323                                 q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1324                                 q[3] = ppp->nxseq;
1325                         } else {
1326                                 q[2] = bits;
1327                                 q[3] = ppp->nxseq >> 16;
1328                                 q[4] = ppp->nxseq >> 8;
1329                                 q[5] = ppp->nxseq;
1330                         }
1331
1332                         /* copy the data in */
1333                         memcpy(q + hdrlen, p, fnb);
1334
1335                         /* try to send it down the channel */
1336                         chan = pch->chan;
1337                         if (!chan->ops->start_xmit(chan, frag))
1338                                 skb_queue_tail(&pch->file.xq, frag);
1339                         pch->had_frag = 1;
1340                         p += fnb;
1341                         len -= fnb;
1342                         ++ppp->nxseq;
1343                         bits = 0;
1344                 }
1345                 spin_unlock_bh(&pch->downl);
1346         } while (len > 0);
1347         ppp->nxchan = i;
1348
1349         return 1;
1350
1351  noskb:
1352         spin_unlock_bh(&pch->downl);
1353         if (ppp->debug & 1)
1354                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1355         ++ppp->stats.tx_errors;
1356         ++ppp->nxseq;
1357         return 1;       /* abandon the frame */
1358 }
1359 #endif /* CONFIG_PPP_MULTILINK */
1360
1361 /*
1362  * Try to send data out on a channel.
1363  */
1364 static void
1365 ppp_channel_push(struct channel *pch)
1366 {
1367         struct sk_buff *skb;
1368         struct ppp *ppp;
1369
1370         spin_lock_bh(&pch->downl);
1371         if (pch->chan != 0) {
1372                 while (skb_queue_len(&pch->file.xq) > 0) {
1373                         skb = skb_dequeue(&pch->file.xq);
1374                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1375                                 /* put the packet back and try again later */
1376                                 skb_queue_head(&pch->file.xq, skb);
1377                                 break;
1378                         }
1379                 }
1380         } else {
1381                 /* channel got deregistered */
1382                 skb_queue_purge(&pch->file.xq);
1383         }
1384         spin_unlock_bh(&pch->downl);
1385         /* see if there is anything from the attached unit to be sent */
1386         if (skb_queue_len(&pch->file.xq) == 0) {
1387                 read_lock_bh(&pch->upl);
1388                 ppp = pch->ppp;
1389                 if (ppp != 0)
1390                         ppp_xmit_process(ppp);
1391                 read_unlock_bh(&pch->upl);
1392         }
1393 }
1394
1395 /*
1396  * Receive-side routines.
1397  */
1398
1399 /* misuse a few fields of the skb for MP reconstruction */
1400 #define sequence        priority
1401 #define BEbits          cb[0]
1402
1403 static inline void
1404 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1405 {
1406         ppp_recv_lock(ppp);
1407         /* ppp->dev == 0 means interface is closing down */
1408         if (ppp->dev != 0)
1409                 ppp_receive_frame(ppp, skb, pch);
1410         else
1411                 kfree_skb(skb);
1412         ppp_recv_unlock(ppp);
1413 }
1414
1415 void
1416 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1417 {
1418         struct channel *pch = chan->ppp;
1419         int proto;
1420
1421         if (pch == 0 || skb->len == 0) {
1422                 kfree_skb(skb);
1423                 return;
1424         }
1425         
1426         proto = PPP_PROTO(skb);
1427         read_lock_bh(&pch->upl);
1428         if (pch->ppp == 0 || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1429                 /* put it on the channel queue */
1430                 skb_queue_tail(&pch->file.rq, skb);
1431                 /* drop old frames if queue too long */
1432                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1433                        && (skb = skb_dequeue(&pch->file.rq)) != 0)
1434                         kfree_skb(skb);
1435                 wake_up_interruptible(&pch->file.rwait);
1436         } else {
1437                 ppp_do_recv(pch->ppp, skb, pch);
1438         }
1439         read_unlock_bh(&pch->upl);
1440 }
1441
1442 /* Put a 0-length skb in the receive queue as an error indication */
1443 void
1444 ppp_input_error(struct ppp_channel *chan, int code)
1445 {
1446         struct channel *pch = chan->ppp;
1447         struct sk_buff *skb;
1448
1449         if (pch == 0)
1450                 return;
1451
1452         read_lock_bh(&pch->upl);
1453         if (pch->ppp != 0) {
1454                 skb = alloc_skb(0, GFP_ATOMIC);
1455                 if (skb != 0) {
1456                         skb->len = 0;           /* probably unnecessary */
1457                         skb->cb[0] = code;
1458                         ppp_do_recv(pch->ppp, skb, pch);
1459                 }
1460         }
1461         read_unlock_bh(&pch->upl);
1462 }
1463
1464 /*
1465  * We come in here to process a received frame.
1466  * The receive side of the ppp unit is locked.
1467  */
1468 static void
1469 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1470 {
1471         if (skb->len >= 2) {
1472 #ifdef CONFIG_PPP_MULTILINK
1473                 /* XXX do channel-level decompression here */
1474                 if (PPP_PROTO(skb) == PPP_MP)
1475                         ppp_receive_mp_frame(ppp, skb, pch);
1476                 else
1477 #endif /* CONFIG_PPP_MULTILINK */
1478                         ppp_receive_nonmp_frame(ppp, skb);
1479                 return;
1480         }
1481
1482         if (skb->len > 0)
1483                 /* note: a 0-length skb is used as an error indication */
1484                 ++ppp->stats.rx_length_errors;
1485
1486         kfree_skb(skb);
1487         ppp_receive_error(ppp);
1488 }
1489
1490 static void
1491 ppp_receive_error(struct ppp *ppp)
1492 {
1493         ++ppp->stats.rx_errors;
1494         if (ppp->vj != 0)
1495                 slhc_toss(ppp->vj);
1496 }
1497
1498 static void
1499 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1500 {
1501         struct sk_buff *ns;
1502         int proto, len, npi;
1503
1504         /*
1505          * Decompress the frame, if compressed.
1506          * Note that some decompressors need to see uncompressed frames
1507          * that come in as well as compressed frames.
1508          */
1509         if (ppp->rc_state != 0 && (ppp->rstate & SC_DECOMP_RUN)
1510             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1511                 skb = ppp_decompress_frame(ppp, skb);
1512
1513         proto = PPP_PROTO(skb);
1514         switch (proto) {
1515         case PPP_VJC_COMP:
1516                 /* decompress VJ compressed packets */
1517                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1518                         goto err;
1519
1520                 if (skb_tailroom(skb) < 124) {
1521                         /* copy to a new sk_buff with more tailroom */
1522                         ns = dev_alloc_skb(skb->len + 128);
1523                         if (ns == 0) {
1524                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1525                                 goto err;
1526                         }
1527                         skb_reserve(ns, 2);
1528                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1529                         kfree_skb(skb);
1530                         skb = ns;
1531                 }
1532                 else if (!pskb_may_pull(skb, skb->len))
1533                         goto err;
1534
1535                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1536                 if (len <= 0) {
1537                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1538                         goto err;
1539                 }
1540                 len += 2;
1541                 if (len > skb->len)
1542                         skb_put(skb, len - skb->len);
1543                 else if (len < skb->len)
1544                         skb_trim(skb, len);
1545                 proto = PPP_IP;
1546                 break;
1547
1548         case PPP_VJC_UNCOMP:
1549                 if (ppp->vj == 0 || (ppp->flags & SC_REJ_COMP_TCP))
1550                         goto err;
1551                 
1552                 /* Until we fix the decompressor need to make sure
1553                  * data portion is linear.
1554                  */
1555                 if (!pskb_may_pull(skb, skb->len)) 
1556                         goto err;
1557
1558                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1559                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1560                         goto err;
1561                 }
1562                 proto = PPP_IP;
1563                 break;
1564
1565         case PPP_CCP:
1566                 ppp_ccp_peek(ppp, skb, 1);
1567                 break;
1568         }
1569
1570         ++ppp->stats.rx_packets;
1571         ppp->stats.rx_bytes += skb->len - 2;
1572
1573         npi = proto_to_npindex(proto);
1574         if (npi < 0) {
1575                 /* control or unknown frame - pass it to pppd */
1576                 skb_queue_tail(&ppp->file.rq, skb);
1577                 /* limit queue length by dropping old frames */
1578                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1579                        && (skb = skb_dequeue(&ppp->file.rq)) != 0)
1580                         kfree_skb(skb);
1581                 /* wake up any process polling or blocking on read */
1582                 wake_up_interruptible(&ppp->file.rwait);
1583
1584         } else {
1585                 /* network protocol frame - give it to the kernel */
1586
1587 #ifdef CONFIG_PPP_FILTER
1588                 /* check if the packet passes the pass and active filters */
1589                 /* the filter instructions are constructed assuming
1590                    a four-byte PPP header on each packet */
1591                 *skb_push(skb, 2) = 0;
1592                 if (ppp->pass_filter
1593                     && sk_run_filter(skb, ppp->pass_filter,
1594                                      ppp->pass_len) == 0) {
1595                         if (ppp->debug & 1)
1596                                 printk(KERN_DEBUG "PPP: inbound frame not passed\n");
1597                         kfree_skb(skb);
1598                         return;
1599                 }
1600                 if (!(ppp->active_filter
1601                       && sk_run_filter(skb, ppp->active_filter,
1602                                        ppp->active_len) == 0))
1603                         ppp->last_recv = jiffies;
1604                 skb_pull(skb, 2);
1605 #else
1606                 ppp->last_recv = jiffies;
1607 #endif /* CONFIG_PPP_FILTER */
1608
1609                 if ((ppp->dev->flags & IFF_UP) == 0
1610                     || ppp->npmode[npi] != NPMODE_PASS) {
1611                         kfree_skb(skb);
1612                 } else {
1613                         skb_pull(skb, 2);       /* chop off protocol */
1614                         skb->dev = ppp->dev;
1615                         skb->protocol = htons(npindex_to_ethertype[npi]);
1616                         skb->mac.raw = skb->data;
1617                         skb->input_dev = ppp->dev;
1618                         netif_rx(skb);
1619                         ppp->dev->last_rx = jiffies;
1620                 }
1621         }
1622         return;
1623
1624  err:
1625         kfree_skb(skb);
1626         ppp_receive_error(ppp);
1627 }
1628
1629 static struct sk_buff *
1630 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1631 {
1632         int proto = PPP_PROTO(skb);
1633         struct sk_buff *ns;
1634         int len;
1635
1636         /* Until we fix all the decompressor's need to make sure
1637          * data portion is linear.
1638          */
1639         if (!pskb_may_pull(skb, skb->len))
1640                 goto err;
1641
1642         if (proto == PPP_COMP) {
1643                 ns = dev_alloc_skb(ppp->mru + PPP_HDRLEN);
1644                 if (ns == 0) {
1645                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1646                         goto err;
1647                 }
1648                 /* the decompressor still expects the A/C bytes in the hdr */
1649                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1650                                 skb->len + 2, ns->data, ppp->mru + PPP_HDRLEN);
1651                 if (len < 0) {
1652                         /* Pass the compressed frame to pppd as an
1653                            error indication. */
1654                         if (len == DECOMP_FATALERROR)
1655                                 ppp->rstate |= SC_DC_FERROR;
1656                         kfree_skb(ns);
1657                         goto err;
1658                 }
1659
1660                 kfree_skb(skb);
1661                 skb = ns;
1662                 skb_put(skb, len);
1663                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1664
1665         } else {
1666                 /* Uncompressed frame - pass to decompressor so it
1667                    can update its dictionary if necessary. */
1668                 if (ppp->rcomp->incomp)
1669                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1670                                            skb->len + 2);
1671         }
1672
1673         return skb;
1674
1675  err:
1676         ppp->rstate |= SC_DC_ERROR;
1677         ppp_receive_error(ppp);
1678         return skb;
1679 }
1680
1681 #ifdef CONFIG_PPP_MULTILINK
1682 /*
1683  * Receive a multilink frame.
1684  * We put it on the reconstruction queue and then pull off
1685  * as many completed frames as we can.
1686  */
1687 static void
1688 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1689 {
1690         u32 mask, seq;
1691         struct list_head *l;
1692         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1693
1694         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1695                 goto err;               /* no good, throw it away */
1696
1697         /* Decode sequence number and begin/end bits */
1698         if (ppp->flags & SC_MP_SHORTSEQ) {
1699                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1700                 mask = 0xfff;
1701         } else {
1702                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1703                 mask = 0xffffff;
1704         }
1705         skb->BEbits = skb->data[2];
1706         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1707
1708         /*
1709          * Do protocol ID decompression on the first fragment of each packet.
1710          */
1711         if ((skb->BEbits & B) && (skb->data[0] & 1))
1712                 *skb_push(skb, 1) = 0;
1713
1714         /*
1715          * Expand sequence number to 32 bits, making it as close
1716          * as possible to ppp->minseq.
1717          */
1718         seq |= ppp->minseq & ~mask;
1719         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1720                 seq += mask + 1;
1721         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1722                 seq -= mask + 1;        /* should never happen */
1723         skb->sequence = seq;
1724         pch->lastseq = seq;
1725
1726         /*
1727          * If this packet comes before the next one we were expecting,
1728          * drop it.
1729          */
1730         if (seq_before(seq, ppp->nextseq)) {
1731                 kfree_skb(skb);
1732                 ++ppp->stats.rx_dropped;
1733                 ppp_receive_error(ppp);
1734                 return;
1735         }
1736
1737         /*
1738          * Reevaluate minseq, the minimum over all channels of the
1739          * last sequence number received on each channel.  Because of
1740          * the increasing sequence number rule, we know that any fragment
1741          * before `minseq' which hasn't arrived is never going to arrive.
1742          * The list of channels can't change because we have the receive
1743          * side of the ppp unit locked.
1744          */
1745         for (l = ppp->channels.next; l != &ppp->channels; l = l->next) {
1746                 struct channel *ch = list_entry(l, struct channel, clist);
1747                 if (seq_before(ch->lastseq, seq))
1748                         seq = ch->lastseq;
1749         }
1750         if (seq_before(ppp->minseq, seq))
1751                 ppp->minseq = seq;
1752
1753         /* Put the fragment on the reconstruction queue */
1754         ppp_mp_insert(ppp, skb);
1755
1756         /* If the queue is getting long, don't wait any longer for packets
1757            before the start of the queue. */
1758         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN
1759             && seq_before(ppp->minseq, ppp->mrq.next->sequence))
1760                 ppp->minseq = ppp->mrq.next->sequence;
1761
1762         /* Pull completed packets off the queue and receive them. */
1763         while ((skb = ppp_mp_reconstruct(ppp)) != 0)
1764                 ppp_receive_nonmp_frame(ppp, skb);
1765
1766         return;
1767
1768  err:
1769         kfree_skb(skb);
1770         ppp_receive_error(ppp);
1771 }
1772
1773 /*
1774  * Insert a fragment on the MP reconstruction queue.
1775  * The queue is ordered by increasing sequence number.
1776  */
1777 static void
1778 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1779 {
1780         struct sk_buff *p;
1781         struct sk_buff_head *list = &ppp->mrq;
1782         u32 seq = skb->sequence;
1783
1784         /* N.B. we don't need to lock the list lock because we have the
1785            ppp unit receive-side lock. */
1786         for (p = list->next; p != (struct sk_buff *)list; p = p->next)
1787                 if (seq_before(seq, p->sequence))
1788                         break;
1789         __skb_insert(skb, p->prev, p, list);
1790 }
1791
1792 /*
1793  * Reconstruct a packet from the MP fragment queue.
1794  * We go through increasing sequence numbers until we find a
1795  * complete packet, or we get to the sequence number for a fragment
1796  * which hasn't arrived but might still do so.
1797  */
1798 struct sk_buff *
1799 ppp_mp_reconstruct(struct ppp *ppp)
1800 {
1801         u32 seq = ppp->nextseq;
1802         u32 minseq = ppp->minseq;
1803         struct sk_buff_head *list = &ppp->mrq;
1804         struct sk_buff *p, *next;
1805         struct sk_buff *head, *tail;
1806         struct sk_buff *skb = NULL;
1807         int lost = 0, len = 0;
1808
1809         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1810                 return NULL;
1811         head = list->next;
1812         tail = NULL;
1813         for (p = head; p != (struct sk_buff *) list; p = next) {
1814                 next = p->next;
1815                 if (seq_before(p->sequence, seq)) {
1816                         /* this can't happen, anyway ignore the skb */
1817                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1818                                p->sequence, seq);
1819                         head = next;
1820                         continue;
1821                 }
1822                 if (p->sequence != seq) {
1823                         /* Fragment `seq' is missing.  If it is after
1824                            minseq, it might arrive later, so stop here. */
1825                         if (seq_after(seq, minseq))
1826                                 break;
1827                         /* Fragment `seq' is lost, keep going. */
1828                         lost = 1;
1829                         seq = seq_before(minseq, p->sequence)?
1830                                 minseq + 1: p->sequence;
1831                         next = p;
1832                         continue;
1833                 }
1834
1835                 /*
1836                  * At this point we know that all the fragments from
1837                  * ppp->nextseq to seq are either present or lost.
1838                  * Also, there are no complete packets in the queue
1839                  * that have no missing fragments and end before this
1840                  * fragment.
1841                  */
1842
1843                 /* B bit set indicates this fragment starts a packet */
1844                 if (p->BEbits & B) {
1845                         head = p;
1846                         lost = 0;
1847                         len = 0;
1848                 }
1849
1850                 len += p->len;
1851
1852                 /* Got a complete packet yet? */
1853                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1854                         if (len > ppp->mrru + 2) {
1855                                 ++ppp->stats.rx_length_errors;
1856                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1857                                        " is too long (%d)\n", len);
1858                         } else if (p == head) {
1859                                 /* fragment is complete packet - reuse skb */
1860                                 tail = p;
1861                                 skb = skb_get(p);
1862                                 break;
1863                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1864                                 ++ppp->stats.rx_missed_errors;
1865                                 printk(KERN_DEBUG "PPP: no memory for "
1866                                        "reconstructed packet");
1867                         } else {
1868                                 tail = p;
1869                                 break;
1870                         }
1871                         ppp->nextseq = seq + 1;
1872                 }
1873
1874                 /*
1875                  * If this is the ending fragment of a packet,
1876                  * and we haven't found a complete valid packet yet,
1877                  * we can discard up to and including this fragment.
1878                  */
1879                 if (p->BEbits & E)
1880                         head = next;
1881
1882                 ++seq;
1883         }
1884
1885         /* If we have a complete packet, copy it all into one skb. */
1886         if (tail != NULL) {
1887                 /* If we have discarded any fragments,
1888                    signal a receive error. */
1889                 if (head->sequence != ppp->nextseq) {
1890                         if (ppp->debug & 1)
1891                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1892                                        ppp->nextseq, head->sequence-1);
1893                         ++ppp->stats.rx_dropped;
1894                         ppp_receive_error(ppp);
1895                 }
1896
1897                 if (head != tail)
1898                         /* copy to a single skb */
1899                         for (p = head; p != tail->next; p = p->next)
1900                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1901                 ppp->nextseq = tail->sequence + 1;
1902                 head = tail->next;
1903         }
1904
1905         /* Discard all the skbuffs that we have copied the data out of
1906            or that we can't use. */
1907         while ((p = list->next) != head) {
1908                 __skb_unlink(p, list);
1909                 kfree_skb(p);
1910         }
1911
1912         return skb;
1913 }
1914 #endif /* CONFIG_PPP_MULTILINK */
1915
1916 /*
1917  * Channel interface.
1918  */
1919
1920 /*
1921  * Create a new, unattached ppp channel.
1922  */
1923 int
1924 ppp_register_channel(struct ppp_channel *chan)
1925 {
1926         struct channel *pch;
1927
1928         pch = kmalloc(sizeof(struct channel), GFP_KERNEL);
1929         if (pch == 0)
1930                 return -ENOMEM;
1931         memset(pch, 0, sizeof(struct channel));
1932         pch->ppp = NULL;
1933         pch->chan = chan;
1934         chan->ppp = pch;
1935         init_ppp_file(&pch->file, CHANNEL);
1936         pch->file.hdrlen = chan->hdrlen;
1937 #ifdef CONFIG_PPP_MULTILINK
1938         pch->lastseq = -1;
1939 #endif /* CONFIG_PPP_MULTILINK */
1940         init_rwsem(&pch->chan_sem);
1941         spin_lock_init(&pch->downl);
1942         rwlock_init(&pch->upl);
1943         spin_lock_bh(&all_channels_lock);
1944         pch->file.index = ++last_channel_index;
1945         list_add(&pch->list, &new_channels);
1946         atomic_inc(&channel_count);
1947         spin_unlock_bh(&all_channels_lock);
1948         return 0;
1949 }
1950
1951 /*
1952  * Return the index of a channel.
1953  */
1954 int ppp_channel_index(struct ppp_channel *chan)
1955 {
1956         struct channel *pch = chan->ppp;
1957
1958         if (pch != 0)
1959                 return pch->file.index;
1960         return -1;
1961 }
1962
1963 /*
1964  * Return the PPP unit number to which a channel is connected.
1965  */
1966 int ppp_unit_number(struct ppp_channel *chan)
1967 {
1968         struct channel *pch = chan->ppp;
1969         int unit = -1;
1970
1971         if (pch != 0) {
1972                 read_lock_bh(&pch->upl);
1973                 if (pch->ppp != 0)
1974                         unit = pch->ppp->file.index;
1975                 read_unlock_bh(&pch->upl);
1976         }
1977         return unit;
1978 }
1979
1980 /*
1981  * Disconnect a channel from the generic layer.
1982  * This must be called in process context.
1983  */
1984 void
1985 ppp_unregister_channel(struct ppp_channel *chan)
1986 {
1987         struct channel *pch = chan->ppp;
1988
1989         if (pch == 0)
1990                 return;         /* should never happen */
1991         chan->ppp = NULL;
1992
1993         /*
1994          * This ensures that we have returned from any calls into the
1995          * the channel's start_xmit or ioctl routine before we proceed.
1996          */
1997         down_write(&pch->chan_sem);
1998         spin_lock_bh(&pch->downl);
1999         pch->chan = NULL;
2000         spin_unlock_bh(&pch->downl);
2001         up_write(&pch->chan_sem);
2002         ppp_disconnect_channel(pch);
2003         spin_lock_bh(&all_channels_lock);
2004         list_del(&pch->list);
2005         spin_unlock_bh(&all_channels_lock);
2006         pch->file.dead = 1;
2007         wake_up_interruptible(&pch->file.rwait);
2008         if (atomic_dec_and_test(&pch->file.refcnt))
2009                 ppp_destroy_channel(pch);
2010 }
2011
2012 /*
2013  * Callback from a channel when it can accept more to transmit.
2014  * This should be called at BH/softirq level, not interrupt level.
2015  */
2016 void
2017 ppp_output_wakeup(struct ppp_channel *chan)
2018 {
2019         struct channel *pch = chan->ppp;
2020
2021         if (pch == 0)
2022                 return;
2023         ppp_channel_push(pch);
2024 }
2025
2026 /*
2027  * Compression control.
2028  */
2029
2030 /* Process the PPPIOCSCOMPRESS ioctl. */
2031 static int
2032 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2033 {
2034         int err;
2035         struct compressor *cp, *ocomp;
2036         struct ppp_option_data data;
2037         void *state, *ostate;
2038         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2039
2040         err = -EFAULT;
2041         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2042             || (data.length <= CCP_MAX_OPTION_LENGTH
2043                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2044                 goto out;
2045         err = -EINVAL;
2046         if (data.length > CCP_MAX_OPTION_LENGTH
2047             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2048                 goto out;
2049
2050         cp = find_compressor(ccp_option[0]);
2051 #ifdef CONFIG_KMOD
2052         if (cp == 0) {
2053                 request_module("ppp-compress-%d", ccp_option[0]);
2054                 cp = find_compressor(ccp_option[0]);
2055         }
2056 #endif /* CONFIG_KMOD */
2057         if (cp == 0)
2058                 goto out;
2059
2060         err = -ENOBUFS;
2061         if (data.transmit) {
2062                 state = cp->comp_alloc(ccp_option, data.length);
2063                 if (state != 0) {
2064                         ppp_xmit_lock(ppp);
2065                         ppp->xstate &= ~SC_COMP_RUN;
2066                         ocomp = ppp->xcomp;
2067                         ostate = ppp->xc_state;
2068                         ppp->xcomp = cp;
2069                         ppp->xc_state = state;
2070                         ppp_xmit_unlock(ppp);
2071                         if (ostate != 0) {
2072                                 ocomp->comp_free(ostate);
2073                                 module_put(ocomp->owner);
2074                         }
2075                         err = 0;
2076                 } else
2077                         module_put(cp->owner);
2078
2079         } else {
2080                 state = cp->decomp_alloc(ccp_option, data.length);
2081                 if (state != 0) {
2082                         ppp_recv_lock(ppp);
2083                         ppp->rstate &= ~SC_DECOMP_RUN;
2084                         ocomp = ppp->rcomp;
2085                         ostate = ppp->rc_state;
2086                         ppp->rcomp = cp;
2087                         ppp->rc_state = state;
2088                         ppp_recv_unlock(ppp);
2089                         if (ostate != 0) {
2090                                 ocomp->decomp_free(ostate);
2091                                 module_put(ocomp->owner);
2092                         }
2093                         err = 0;
2094                 } else
2095                         module_put(cp->owner);
2096         }
2097
2098  out:
2099         return err;
2100 }
2101
2102 /*
2103  * Look at a CCP packet and update our state accordingly.
2104  * We assume the caller has the xmit or recv path locked.
2105  */
2106 static void
2107 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2108 {
2109         unsigned char *dp;
2110         int len;
2111
2112         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2113                 return; /* no header */
2114         dp = skb->data + 2;
2115
2116         switch (CCP_CODE(dp)) {
2117         case CCP_CONFREQ:
2118
2119                 /* A ConfReq starts negotiation of compression 
2120                  * in one direction of transmission,
2121                  * and hence brings it down...but which way?
2122                  *
2123                  * Remember:
2124                  * A ConfReq indicates what the sender would like to receive
2125                  */
2126                 if(inbound)
2127                         /* He is proposing what I should send */
2128                         ppp->xstate &= ~SC_COMP_RUN;
2129                 else    
2130                         /* I am proposing to what he should send */
2131                         ppp->rstate &= ~SC_DECOMP_RUN;
2132                 
2133                 break;
2134                 
2135         case CCP_TERMREQ:
2136         case CCP_TERMACK:
2137                 /*
2138                  * CCP is going down, both directions of transmission 
2139                  */
2140                 ppp->rstate &= ~SC_DECOMP_RUN;
2141                 ppp->xstate &= ~SC_COMP_RUN;
2142                 break;
2143
2144         case CCP_CONFACK:
2145                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2146                         break;
2147                 len = CCP_LENGTH(dp);
2148                 if (!pskb_may_pull(skb, len + 2))
2149                         return;         /* too short */
2150                 dp += CCP_HDRLEN;
2151                 len -= CCP_HDRLEN;
2152                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2153                         break;
2154                 if (inbound) {
2155                         /* we will start receiving compressed packets */
2156                         if (ppp->rc_state == 0)
2157                                 break;
2158                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2159                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2160                                 ppp->rstate |= SC_DECOMP_RUN;
2161                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2162                         }
2163                 } else {
2164                         /* we will soon start sending compressed packets */
2165                         if (ppp->xc_state == 0)
2166                                 break;
2167                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2168                                         ppp->file.index, 0, ppp->debug))
2169                                 ppp->xstate |= SC_COMP_RUN;
2170                 }
2171                 break;
2172
2173         case CCP_RESETACK:
2174                 /* reset the [de]compressor */
2175                 if ((ppp->flags & SC_CCP_UP) == 0)
2176                         break;
2177                 if (inbound) {
2178                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2179                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2180                                 ppp->rstate &= ~SC_DC_ERROR;
2181                         }
2182                 } else {
2183                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2184                                 ppp->xcomp->comp_reset(ppp->xc_state);
2185                 }
2186                 break;
2187         }
2188 }
2189
2190 /* Free up compression resources. */
2191 static void
2192 ppp_ccp_closed(struct ppp *ppp)
2193 {
2194         void *xstate, *rstate;
2195         struct compressor *xcomp, *rcomp;
2196
2197         ppp_lock(ppp);
2198         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2199         ppp->xstate = 0;
2200         xcomp = ppp->xcomp;
2201         xstate = ppp->xc_state;
2202         ppp->xc_state = NULL;
2203         ppp->rstate = 0;
2204         rcomp = ppp->rcomp;
2205         rstate = ppp->rc_state;
2206         ppp->rc_state = NULL;
2207         ppp_unlock(ppp);
2208
2209         if (xstate) {
2210                 xcomp->comp_free(xstate);
2211                 module_put(xcomp->owner);
2212         }
2213         if (rstate) {
2214                 rcomp->decomp_free(rstate);
2215                 module_put(rcomp->owner);
2216         }
2217 }
2218
2219 /* List of compressors. */
2220 static LIST_HEAD(compressor_list);
2221 static DEFINE_SPINLOCK(compressor_list_lock);
2222
2223 struct compressor_entry {
2224         struct list_head list;
2225         struct compressor *comp;
2226 };
2227
2228 static struct compressor_entry *
2229 find_comp_entry(int proto)
2230 {
2231         struct compressor_entry *ce;
2232         struct list_head *list = &compressor_list;
2233
2234         while ((list = list->next) != &compressor_list) {
2235                 ce = list_entry(list, struct compressor_entry, list);
2236                 if (ce->comp->compress_proto == proto)
2237                         return ce;
2238         }
2239         return NULL;
2240 }
2241
2242 /* Register a compressor */
2243 int
2244 ppp_register_compressor(struct compressor *cp)
2245 {
2246         struct compressor_entry *ce;
2247         int ret;
2248         spin_lock(&compressor_list_lock);
2249         ret = -EEXIST;
2250         if (find_comp_entry(cp->compress_proto) != 0)
2251                 goto out;
2252         ret = -ENOMEM;
2253         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2254         if (ce == 0)
2255                 goto out;
2256         ret = 0;
2257         ce->comp = cp;
2258         list_add(&ce->list, &compressor_list);
2259  out:
2260         spin_unlock(&compressor_list_lock);
2261         return ret;
2262 }
2263
2264 /* Unregister a compressor */
2265 void
2266 ppp_unregister_compressor(struct compressor *cp)
2267 {
2268         struct compressor_entry *ce;
2269
2270         spin_lock(&compressor_list_lock);
2271         ce = find_comp_entry(cp->compress_proto);
2272         if (ce != 0 && ce->comp == cp) {
2273                 list_del(&ce->list);
2274                 kfree(ce);
2275         }
2276         spin_unlock(&compressor_list_lock);
2277 }
2278
2279 /* Find a compressor. */
2280 static struct compressor *
2281 find_compressor(int type)
2282 {
2283         struct compressor_entry *ce;
2284         struct compressor *cp = NULL;
2285
2286         spin_lock(&compressor_list_lock);
2287         ce = find_comp_entry(type);
2288         if (ce != 0) {
2289                 cp = ce->comp;
2290                 if (!try_module_get(cp->owner))
2291                         cp = NULL;
2292         }
2293         spin_unlock(&compressor_list_lock);
2294         return cp;
2295 }
2296
2297 /*
2298  * Miscelleneous stuff.
2299  */
2300
2301 static void
2302 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2303 {
2304         struct slcompress *vj = ppp->vj;
2305
2306         memset(st, 0, sizeof(*st));
2307         st->p.ppp_ipackets = ppp->stats.rx_packets;
2308         st->p.ppp_ierrors = ppp->stats.rx_errors;
2309         st->p.ppp_ibytes = ppp->stats.rx_bytes;
2310         st->p.ppp_opackets = ppp->stats.tx_packets;
2311         st->p.ppp_oerrors = ppp->stats.tx_errors;
2312         st->p.ppp_obytes = ppp->stats.tx_bytes;
2313         if (vj == 0)
2314                 return;
2315         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2316         st->vj.vjs_compressed = vj->sls_o_compressed;
2317         st->vj.vjs_searches = vj->sls_o_searches;
2318         st->vj.vjs_misses = vj->sls_o_misses;
2319         st->vj.vjs_errorin = vj->sls_i_error;
2320         st->vj.vjs_tossed = vj->sls_i_tossed;
2321         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2322         st->vj.vjs_compressedin = vj->sls_i_compressed;
2323 }
2324
2325 /*
2326  * Stuff for handling the lists of ppp units and channels
2327  * and for initialization.
2328  */
2329
2330 /*
2331  * Create a new ppp interface unit.  Fails if it can't allocate memory
2332  * or if there is already a unit with the requested number.
2333  * unit == -1 means allocate a new number.
2334  */
2335 static struct ppp *
2336 ppp_create_interface(int unit, int *retp)
2337 {
2338         struct ppp *ppp;
2339         struct net_device *dev = NULL;
2340         int ret = -ENOMEM;
2341         int i;
2342
2343         ppp = kmalloc(sizeof(struct ppp), GFP_KERNEL);
2344         if (!ppp)
2345                 goto out;
2346         dev = alloc_netdev(0, "", ppp_setup);
2347         if (!dev)
2348                 goto out1;
2349         memset(ppp, 0, sizeof(struct ppp));
2350
2351         ppp->mru = PPP_MRU;
2352         init_ppp_file(&ppp->file, INTERFACE);
2353         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2354         for (i = 0; i < NUM_NP; ++i)
2355                 ppp->npmode[i] = NPMODE_PASS;
2356         INIT_LIST_HEAD(&ppp->channels);
2357         spin_lock_init(&ppp->rlock);
2358         spin_lock_init(&ppp->wlock);
2359 #ifdef CONFIG_PPP_MULTILINK
2360         ppp->minseq = -1;
2361         skb_queue_head_init(&ppp->mrq);
2362 #endif /* CONFIG_PPP_MULTILINK */
2363         ppp->dev = dev;
2364         dev->priv = ppp;
2365
2366         dev->hard_start_xmit = ppp_start_xmit;
2367         dev->get_stats = ppp_net_stats;
2368         dev->do_ioctl = ppp_net_ioctl;
2369
2370         ret = -EEXIST;
2371         down(&all_ppp_sem);
2372         if (unit < 0)
2373                 unit = cardmap_find_first_free(all_ppp_units);
2374         else if (cardmap_get(all_ppp_units, unit) != NULL)
2375                 goto out2;      /* unit already exists */
2376
2377         /* Initialize the new ppp unit */
2378         ppp->file.index = unit;
2379         sprintf(dev->name, "ppp%d", unit);
2380
2381         ret = register_netdev(dev);
2382         if (ret != 0) {
2383                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2384                        dev->name, ret);
2385                 goto out2;
2386         }
2387
2388         atomic_inc(&ppp_unit_count);
2389         cardmap_set(&all_ppp_units, unit, ppp);
2390         up(&all_ppp_sem);
2391         *retp = 0;
2392         return ppp;
2393
2394 out2:
2395         up(&all_ppp_sem);
2396         free_netdev(dev);
2397 out1:
2398         kfree(ppp);
2399 out:
2400         *retp = ret;
2401         return NULL;
2402 }
2403
2404 /*
2405  * Initialize a ppp_file structure.
2406  */
2407 static void
2408 init_ppp_file(struct ppp_file *pf, int kind)
2409 {
2410         pf->kind = kind;
2411         skb_queue_head_init(&pf->xq);
2412         skb_queue_head_init(&pf->rq);
2413         atomic_set(&pf->refcnt, 1);
2414         init_waitqueue_head(&pf->rwait);
2415 }
2416
2417 /*
2418  * Take down a ppp interface unit - called when the owning file
2419  * (the one that created the unit) is closed or detached.
2420  */
2421 static void ppp_shutdown_interface(struct ppp *ppp)
2422 {
2423         struct net_device *dev;
2424
2425         down(&all_ppp_sem);
2426         ppp_lock(ppp);
2427         dev = ppp->dev;
2428         ppp->dev = NULL;
2429         ppp_unlock(ppp);
2430         /* This will call dev_close() for us. */
2431         if (dev) {
2432                 unregister_netdev(dev);
2433                 free_netdev(dev);
2434         }
2435         cardmap_set(&all_ppp_units, ppp->file.index, NULL);
2436         ppp->file.dead = 1;
2437         ppp->owner = NULL;
2438         wake_up_interruptible(&ppp->file.rwait);
2439         up(&all_ppp_sem);
2440 }
2441
2442 /*
2443  * Free the memory used by a ppp unit.  This is only called once
2444  * there are no channels connected to the unit and no file structs
2445  * that reference the unit.
2446  */
2447 static void ppp_destroy_interface(struct ppp *ppp)
2448 {
2449         atomic_dec(&ppp_unit_count);
2450
2451         if (!ppp->file.dead || ppp->n_channels) {
2452                 /* "can't happen" */
2453                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2454                        "n_channels=%d !\n", ppp, ppp->file.dead,
2455                        ppp->n_channels);
2456                 return;
2457         }
2458
2459         ppp_ccp_closed(ppp);
2460         if (ppp->vj) {
2461                 slhc_free(ppp->vj);
2462                 ppp->vj = NULL;
2463         }
2464         skb_queue_purge(&ppp->file.xq);
2465         skb_queue_purge(&ppp->file.rq);
2466 #ifdef CONFIG_PPP_MULTILINK
2467         skb_queue_purge(&ppp->mrq);
2468 #endif /* CONFIG_PPP_MULTILINK */
2469 #ifdef CONFIG_PPP_FILTER
2470         kfree(ppp->pass_filter);
2471         ppp->pass_filter = NULL;
2472         kfree(ppp->active_filter);
2473         ppp->active_filter = NULL;
2474 #endif /* CONFIG_PPP_FILTER */
2475
2476         kfree(ppp);
2477 }
2478
2479 /*
2480  * Locate an existing ppp unit.
2481  * The caller should have locked the all_ppp_sem.
2482  */
2483 static struct ppp *
2484 ppp_find_unit(int unit)
2485 {
2486         return cardmap_get(all_ppp_units, unit);
2487 }
2488
2489 /*
2490  * Locate an existing ppp channel.
2491  * The caller should have locked the all_channels_lock.
2492  * First we look in the new_channels list, then in the
2493  * all_channels list.  If found in the new_channels list,
2494  * we move it to the all_channels list.  This is for speed
2495  * when we have a lot of channels in use.
2496  */
2497 static struct channel *
2498 ppp_find_channel(int unit)
2499 {
2500         struct channel *pch;
2501         struct list_head *list;
2502
2503         list = &new_channels;
2504         while ((list = list->next) != &new_channels) {
2505                 pch = list_entry(list, struct channel, list);
2506                 if (pch->file.index == unit) {
2507                         list_del(&pch->list);
2508                         list_add(&pch->list, &all_channels);
2509                         return pch;
2510                 }
2511         }
2512         list = &all_channels;
2513         while ((list = list->next) != &all_channels) {
2514                 pch = list_entry(list, struct channel, list);
2515                 if (pch->file.index == unit)
2516                         return pch;
2517         }
2518         return NULL;
2519 }
2520
2521 /*
2522  * Connect a PPP channel to a PPP interface unit.
2523  */
2524 static int
2525 ppp_connect_channel(struct channel *pch, int unit)
2526 {
2527         struct ppp *ppp;
2528         int ret = -ENXIO;
2529         int hdrlen;
2530
2531         down(&all_ppp_sem);
2532         ppp = ppp_find_unit(unit);
2533         if (ppp == 0)
2534                 goto out;
2535         write_lock_bh(&pch->upl);
2536         ret = -EINVAL;
2537         if (pch->ppp != 0)
2538                 goto outl;
2539
2540         ppp_lock(ppp);
2541         if (pch->file.hdrlen > ppp->file.hdrlen)
2542                 ppp->file.hdrlen = pch->file.hdrlen;
2543         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2544         if (ppp->dev && hdrlen > ppp->dev->hard_header_len)
2545                 ppp->dev->hard_header_len = hdrlen;
2546         list_add_tail(&pch->clist, &ppp->channels);
2547         ++ppp->n_channels;
2548         pch->ppp = ppp;
2549         atomic_inc(&ppp->file.refcnt);
2550         ppp_unlock(ppp);
2551         ret = 0;
2552
2553  outl:
2554         write_unlock_bh(&pch->upl);
2555  out:
2556         up(&all_ppp_sem);
2557         return ret;
2558 }
2559
2560 /*
2561  * Disconnect a channel from its ppp unit.
2562  */
2563 static int
2564 ppp_disconnect_channel(struct channel *pch)
2565 {
2566         struct ppp *ppp;
2567         int err = -EINVAL;
2568
2569         write_lock_bh(&pch->upl);
2570         ppp = pch->ppp;
2571         pch->ppp = NULL;
2572         write_unlock_bh(&pch->upl);
2573         if (ppp != 0) {
2574                 /* remove it from the ppp unit's list */
2575                 ppp_lock(ppp);
2576                 list_del(&pch->clist);
2577                 if (--ppp->n_channels == 0)
2578                         wake_up_interruptible(&ppp->file.rwait);
2579                 ppp_unlock(ppp);
2580                 if (atomic_dec_and_test(&ppp->file.refcnt))
2581                         ppp_destroy_interface(ppp);
2582                 err = 0;
2583         }
2584         return err;
2585 }
2586
2587 /*
2588  * Free up the resources used by a ppp channel.
2589  */
2590 static void ppp_destroy_channel(struct channel *pch)
2591 {
2592         atomic_dec(&channel_count);
2593
2594         if (!pch->file.dead) {
2595                 /* "can't happen" */
2596                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2597                        pch);
2598                 return;
2599         }
2600         skb_queue_purge(&pch->file.xq);
2601         skb_queue_purge(&pch->file.rq);
2602         kfree(pch);
2603 }
2604
2605 static void __exit ppp_cleanup(void)
2606 {
2607         /* should never happen */
2608         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2609                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2610         cardmap_destroy(&all_ppp_units);
2611         if (unregister_chrdev(PPP_MAJOR, "ppp") != 0)
2612                 printk(KERN_ERR "PPP: failed to unregister PPP device\n");
2613         devfs_remove("ppp");
2614         class_simple_device_remove(MKDEV(PPP_MAJOR, 0));
2615         class_simple_destroy(ppp_class);
2616 }
2617
2618 /*
2619  * Cardmap implementation.
2620  */
2621 static void *cardmap_get(struct cardmap *map, unsigned int nr)
2622 {
2623         struct cardmap *p;
2624         int i;
2625
2626         for (p = map; p != NULL; ) {
2627                 if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
2628                         return NULL;
2629                 if (p->shift == 0)
2630                         return p->ptr[i];
2631                 nr &= ~(CARDMAP_MASK << p->shift);
2632                 p = p->ptr[i];
2633         }
2634         return NULL;
2635 }
2636
2637 static void cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
2638 {
2639         struct cardmap *p;
2640         int i;
2641
2642         p = *pmap;
2643         if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
2644                 do {
2645                         /* need a new top level */
2646                         struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
2647                         memset(np, 0, sizeof(*np));
2648                         np->ptr[0] = p;
2649                         if (p != NULL) {
2650                                 np->shift = p->shift + CARDMAP_ORDER;
2651                                 p->parent = np;
2652                         } else
2653                                 np->shift = 0;
2654                         p = np;
2655                 } while ((nr >> p->shift) >= CARDMAP_WIDTH);
2656                 *pmap = p;
2657         }
2658         while (p->shift > 0) {
2659                 i = (nr >> p->shift) & CARDMAP_MASK;
2660                 if (p->ptr[i] == NULL) {
2661                         struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
2662                         memset(np, 0, sizeof(*np));
2663                         np->shift = p->shift - CARDMAP_ORDER;
2664                         np->parent = p;
2665                         p->ptr[i] = np;
2666                 }
2667                 if (ptr == NULL)
2668                         clear_bit(i, &p->inuse);
2669                 p = p->ptr[i];
2670         }
2671         i = nr & CARDMAP_MASK;
2672         p->ptr[i] = ptr;
2673         if (ptr != NULL)
2674                 set_bit(i, &p->inuse);
2675         else
2676                 clear_bit(i, &p->inuse);
2677 }
2678
2679 static unsigned int cardmap_find_first_free(struct cardmap *map)
2680 {
2681         struct cardmap *p;
2682         unsigned int nr = 0;
2683         int i;
2684
2685         if ((p = map) == NULL)
2686                 return 0;
2687         for (;;) {
2688                 i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
2689                 if (i >= CARDMAP_WIDTH) {
2690                         if (p->parent == NULL)
2691                                 return CARDMAP_WIDTH << p->shift;
2692                         p = p->parent;
2693                         i = (nr >> p->shift) & CARDMAP_MASK;
2694                         set_bit(i, &p->inuse);
2695                         continue;
2696                 }
2697                 nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
2698                 if (p->shift == 0 || p->ptr[i] == NULL)
2699                         return nr;
2700                 p = p->ptr[i];
2701         }
2702 }
2703
2704 static void cardmap_destroy(struct cardmap **pmap)
2705 {
2706         struct cardmap *p, *np;
2707         int i;
2708
2709         for (p = *pmap; p != NULL; p = np) {
2710                 if (p->shift != 0) {
2711                         for (i = 0; i < CARDMAP_WIDTH; ++i)
2712                                 if (p->ptr[i] != NULL)
2713                                         break;
2714                         if (i < CARDMAP_WIDTH) {
2715                                 np = p->ptr[i];
2716                                 p->ptr[i] = NULL;
2717                                 continue;
2718                         }
2719                 }
2720                 np = p->parent;
2721                 kfree(p);
2722         }
2723         *pmap = NULL;
2724 }
2725
2726 /* Module/initialization stuff */
2727
2728 module_init(ppp_init);
2729 module_exit(ppp_cleanup);
2730
2731 EXPORT_SYMBOL(ppp_register_channel);
2732 EXPORT_SYMBOL(ppp_unregister_channel);
2733 EXPORT_SYMBOL(ppp_channel_index);
2734 EXPORT_SYMBOL(ppp_unit_number);
2735 EXPORT_SYMBOL(ppp_input);
2736 EXPORT_SYMBOL(ppp_input_error);
2737 EXPORT_SYMBOL(ppp_output_wakeup);
2738 EXPORT_SYMBOL(ppp_register_compressor);
2739 EXPORT_SYMBOL(ppp_unregister_compressor);
2740 MODULE_LICENSE("GPL");
2741 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2742 MODULE_ALIAS("/dev/ppp");