[PATCH] f_count may wrap around
[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/module.h>
26 #include <linux/kernel.h>
27 #include <linux/kmod.h>
28 #include <linux/init.h>
29 #include <linux/list.h>
30 #include <linux/netdevice.h>
31 #include <linux/poll.h>
32 #include <linux/ppp_defs.h>
33 #include <linux/filter.h>
34 #include <linux/if_ppp.h>
35 #include <linux/ppp_channel.h>
36 #include <linux/ppp-comp.h>
37 #include <linux/skbuff.h>
38 #include <linux/rtnetlink.h>
39 #include <linux/if_arp.h>
40 #include <linux/ip.h>
41 #include <linux/tcp.h>
42 #include <linux/smp_lock.h>
43 #include <linux/spinlock.h>
44 #include <linux/rwsem.h>
45 #include <linux/stddef.h>
46 #include <linux/device.h>
47 #include <linux/mutex.h>
48 #include <net/slhc_vj.h>
49 #include <asm/atomic.h>
50
51 #define PPP_VERSION     "2.4.2"
52
53 /*
54  * Network protocols we support.
55  */
56 #define NP_IP   0               /* Internet Protocol V4 */
57 #define NP_IPV6 1               /* Internet Protocol V6 */
58 #define NP_IPX  2               /* IPX protocol */
59 #define NP_AT   3               /* Appletalk protocol */
60 #define NP_MPLS_UC 4            /* MPLS unicast */
61 #define NP_MPLS_MC 5            /* MPLS multicast */
62 #define NUM_NP  6               /* Number of NPs. */
63
64 #define MPHDRLEN        6       /* multilink protocol header length */
65 #define MPHDRLEN_SSN    4       /* ditto with short sequence numbers */
66 #define MIN_FRAG_SIZE   64
67
68 /*
69  * An instance of /dev/ppp can be associated with either a ppp
70  * interface unit or a ppp channel.  In both cases, file->private_data
71  * points to one of these.
72  */
73 struct ppp_file {
74         enum {
75                 INTERFACE=1, CHANNEL
76         }               kind;
77         struct sk_buff_head xq;         /* pppd transmit queue */
78         struct sk_buff_head rq;         /* receive queue for pppd */
79         wait_queue_head_t rwait;        /* for poll on reading /dev/ppp */
80         atomic_t        refcnt;         /* # refs (incl /dev/ppp attached) */
81         int             hdrlen;         /* space to leave for headers */
82         int             index;          /* interface unit / channel number */
83         int             dead;           /* unit/channel has been shut down */
84 };
85
86 #define PF_TO_X(pf, X)          container_of(pf, X, file)
87
88 #define PF_TO_PPP(pf)           PF_TO_X(pf, struct ppp)
89 #define PF_TO_CHANNEL(pf)       PF_TO_X(pf, struct channel)
90
91 /*
92  * Data structure describing one ppp unit.
93  * A ppp unit corresponds to a ppp network interface device
94  * and represents a multilink bundle.
95  * It can have 0 or more ppp channels connected to it.
96  */
97 struct ppp {
98         struct ppp_file file;           /* stuff for read/write/poll 0 */
99         struct file     *owner;         /* file that owns this unit 48 */
100         struct list_head channels;      /* list of attached channels 4c */
101         int             n_channels;     /* how many channels are attached 54 */
102         spinlock_t      rlock;          /* lock for receive side 58 */
103         spinlock_t      wlock;          /* lock for transmit side 5c */
104         int             mru;            /* max receive unit 60 */
105         unsigned int    flags;          /* control bits 64 */
106         unsigned int    xstate;         /* transmit state bits 68 */
107         unsigned int    rstate;         /* receive state bits 6c */
108         int             debug;          /* debug flags 70 */
109         struct slcompress *vj;          /* state for VJ header compression */
110         enum NPmode     npmode[NUM_NP]; /* what to do with each net proto 78 */
111         struct sk_buff  *xmit_pending;  /* a packet ready to go out 88 */
112         struct compressor *xcomp;       /* transmit packet compressor 8c */
113         void            *xc_state;      /* its internal state 90 */
114         struct compressor *rcomp;       /* receive decompressor 94 */
115         void            *rc_state;      /* its internal state 98 */
116         unsigned long   last_xmit;      /* jiffies when last pkt sent 9c */
117         unsigned long   last_recv;      /* jiffies when last pkt rcvd a0 */
118         struct net_device *dev;         /* network interface device a4 */
119 #ifdef CONFIG_PPP_MULTILINK
120         int             nxchan;         /* next channel to send something on */
121         u32             nxseq;          /* next sequence number to send */
122         int             mrru;           /* MP: max reconst. receive unit */
123         u32             nextseq;        /* MP: seq no of next packet */
124         u32             minseq;         /* MP: min of most recent seqnos */
125         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
126 #endif /* CONFIG_PPP_MULTILINK */
127 #ifdef CONFIG_PPP_FILTER
128         struct sock_filter *pass_filter;        /* filter for packets to pass */
129         struct sock_filter *active_filter;/* filter for pkts to reset idle */
130         unsigned pass_len, active_len;
131 #endif /* CONFIG_PPP_FILTER */
132 };
133
134 /*
135  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
136  * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
137  * SC_MUST_COMP
138  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
139  * Bits in xstate: SC_COMP_RUN
140  */
141 #define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
142                          |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
143                          |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
144
145 /*
146  * Private data structure for each channel.
147  * This includes the data structure used for multilink.
148  */
149 struct channel {
150         struct ppp_file file;           /* stuff for read/write/poll */
151         struct list_head list;          /* link in all/new_channels list */
152         struct ppp_channel *chan;       /* public channel data structure */
153         struct rw_semaphore chan_sem;   /* protects `chan' during chan ioctl */
154         spinlock_t      downl;          /* protects `chan', file.xq dequeue */
155         struct ppp      *ppp;           /* ppp unit we're connected to */
156         struct list_head clist;         /* link in list of channels per unit */
157         rwlock_t        upl;            /* protects `ppp' */
158 #ifdef CONFIG_PPP_MULTILINK
159         u8              avail;          /* flag used in multilink stuff */
160         u8              had_frag;       /* >= 1 fragments have been sent */
161         u32             lastseq;        /* MP: last sequence # received */
162 #endif /* CONFIG_PPP_MULTILINK */
163 };
164
165 /*
166  * SMP locking issues:
167  * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
168  * list and the ppp.n_channels field, you need to take both locks
169  * before you modify them.
170  * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
171  * channel.downl.
172  */
173
174 /*
175  * A cardmap represents a mapping from unsigned integers to pointers,
176  * and provides a fast "find lowest unused number" operation.
177  * It uses a broad (32-way) tree with a bitmap at each level.
178  * It is designed to be space-efficient for small numbers of entries
179  * and time-efficient for large numbers of entries.
180  */
181 #define CARDMAP_ORDER   5
182 #define CARDMAP_WIDTH   (1U << CARDMAP_ORDER)
183 #define CARDMAP_MASK    (CARDMAP_WIDTH - 1)
184
185 struct cardmap {
186         int shift;
187         unsigned long inuse;
188         struct cardmap *parent;
189         void *ptr[CARDMAP_WIDTH];
190 };
191 static void *cardmap_get(struct cardmap *map, unsigned int nr);
192 static int cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
193 static unsigned int cardmap_find_first_free(struct cardmap *map);
194 static void cardmap_destroy(struct cardmap **map);
195
196 /*
197  * all_ppp_mutex protects the all_ppp_units mapping.
198  * It also ensures that finding a ppp unit in the all_ppp_units map
199  * and updating its file.refcnt field is atomic.
200  */
201 static DEFINE_MUTEX(all_ppp_mutex);
202 static struct cardmap *all_ppp_units;
203 static atomic_t ppp_unit_count = ATOMIC_INIT(0);
204
205 /*
206  * all_channels_lock protects all_channels and last_channel_index,
207  * and the atomicity of find a channel and updating its file.refcnt
208  * field.
209  */
210 static DEFINE_SPINLOCK(all_channels_lock);
211 static LIST_HEAD(all_channels);
212 static LIST_HEAD(new_channels);
213 static int last_channel_index;
214 static atomic_t channel_count = ATOMIC_INIT(0);
215
216 /* Get the PPP protocol number from a skb */
217 #define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])
218
219 /* We limit the length of ppp->file.rq to this (arbitrary) value */
220 #define PPP_MAX_RQLEN   32
221
222 /*
223  * Maximum number of multilink fragments queued up.
224  * This has to be large enough to cope with the maximum latency of
225  * the slowest channel relative to the others.  Strictly it should
226  * depend on the number of channels and their characteristics.
227  */
228 #define PPP_MP_MAX_QLEN 128
229
230 /* Multilink header bits. */
231 #define B       0x80            /* this fragment begins a packet */
232 #define E       0x40            /* this fragment ends a packet */
233
234 /* Compare multilink sequence numbers (assumed to be 32 bits wide) */
235 #define seq_before(a, b)        ((s32)((a) - (b)) < 0)
236 #define seq_after(a, b)         ((s32)((a) - (b)) > 0)
237
238 /* Prototypes. */
239 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
240                                 unsigned int cmd, unsigned long arg);
241 static void ppp_xmit_process(struct ppp *ppp);
242 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
243 static void ppp_push(struct ppp *ppp);
244 static void ppp_channel_push(struct channel *pch);
245 static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
246                               struct channel *pch);
247 static void ppp_receive_error(struct ppp *ppp);
248 static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
249 static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
250                                             struct sk_buff *skb);
251 #ifdef CONFIG_PPP_MULTILINK
252 static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
253                                 struct channel *pch);
254 static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
255 static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
256 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
257 #endif /* CONFIG_PPP_MULTILINK */
258 static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
259 static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
260 static void ppp_ccp_closed(struct ppp *ppp);
261 static struct compressor *find_compressor(int type);
262 static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
263 static struct ppp *ppp_create_interface(int unit, int *retp);
264 static void init_ppp_file(struct ppp_file *pf, int kind);
265 static void ppp_shutdown_interface(struct ppp *ppp);
266 static void ppp_destroy_interface(struct ppp *ppp);
267 static struct ppp *ppp_find_unit(int unit);
268 static struct channel *ppp_find_channel(int unit);
269 static int ppp_connect_channel(struct channel *pch, int unit);
270 static int ppp_disconnect_channel(struct channel *pch);
271 static void ppp_destroy_channel(struct channel *pch);
272
273 static struct class *ppp_class;
274
275 /* Translates a PPP protocol number to a NP index (NP == network protocol) */
276 static inline int proto_to_npindex(int proto)
277 {
278         switch (proto) {
279         case PPP_IP:
280                 return NP_IP;
281         case PPP_IPV6:
282                 return NP_IPV6;
283         case PPP_IPX:
284                 return NP_IPX;
285         case PPP_AT:
286                 return NP_AT;
287         case PPP_MPLS_UC:
288                 return NP_MPLS_UC;
289         case PPP_MPLS_MC:
290                 return NP_MPLS_MC;
291         }
292         return -EINVAL;
293 }
294
295 /* Translates an NP index into a PPP protocol number */
296 static const int npindex_to_proto[NUM_NP] = {
297         PPP_IP,
298         PPP_IPV6,
299         PPP_IPX,
300         PPP_AT,
301         PPP_MPLS_UC,
302         PPP_MPLS_MC,
303 };
304
305 /* Translates an ethertype into an NP index */
306 static inline int ethertype_to_npindex(int ethertype)
307 {
308         switch (ethertype) {
309         case ETH_P_IP:
310                 return NP_IP;
311         case ETH_P_IPV6:
312                 return NP_IPV6;
313         case ETH_P_IPX:
314                 return NP_IPX;
315         case ETH_P_PPPTALK:
316         case ETH_P_ATALK:
317                 return NP_AT;
318         case ETH_P_MPLS_UC:
319                 return NP_MPLS_UC;
320         case ETH_P_MPLS_MC:
321                 return NP_MPLS_MC;
322         }
323         return -1;
324 }
325
326 /* Translates an NP index into an ethertype */
327 static const int npindex_to_ethertype[NUM_NP] = {
328         ETH_P_IP,
329         ETH_P_IPV6,
330         ETH_P_IPX,
331         ETH_P_PPPTALK,
332         ETH_P_MPLS_UC,
333         ETH_P_MPLS_MC,
334 };
335
336 /*
337  * Locking shorthand.
338  */
339 #define ppp_xmit_lock(ppp)      spin_lock_bh(&(ppp)->wlock)
340 #define ppp_xmit_unlock(ppp)    spin_unlock_bh(&(ppp)->wlock)
341 #define ppp_recv_lock(ppp)      spin_lock_bh(&(ppp)->rlock)
342 #define ppp_recv_unlock(ppp)    spin_unlock_bh(&(ppp)->rlock)
343 #define ppp_lock(ppp)           do { ppp_xmit_lock(ppp); \
344                                      ppp_recv_lock(ppp); } while (0)
345 #define ppp_unlock(ppp)         do { ppp_recv_unlock(ppp); \
346                                      ppp_xmit_unlock(ppp); } while (0)
347
348 /*
349  * /dev/ppp device routines.
350  * The /dev/ppp device is used by pppd to control the ppp unit.
351  * It supports the read, write, ioctl and poll functions.
352  * Open instances of /dev/ppp can be in one of three states:
353  * unattached, attached to a ppp unit, or attached to a ppp channel.
354  */
355 static int ppp_open(struct inode *inode, struct file *file)
356 {
357         cycle_kernel_lock();
358         /*
359          * This could (should?) be enforced by the permissions on /dev/ppp.
360          */
361         if (!capable(CAP_NET_ADMIN))
362                 return -EPERM;
363         return 0;
364 }
365
366 static int ppp_release(struct inode *unused, struct file *file)
367 {
368         struct ppp_file *pf = file->private_data;
369         struct ppp *ppp;
370
371         if (pf) {
372                 file->private_data = NULL;
373                 if (pf->kind == INTERFACE) {
374                         ppp = PF_TO_PPP(pf);
375                         if (file == ppp->owner)
376                                 ppp_shutdown_interface(ppp);
377                 }
378                 if (atomic_dec_and_test(&pf->refcnt)) {
379                         switch (pf->kind) {
380                         case INTERFACE:
381                                 ppp_destroy_interface(PF_TO_PPP(pf));
382                                 break;
383                         case CHANNEL:
384                                 ppp_destroy_channel(PF_TO_CHANNEL(pf));
385                                 break;
386                         }
387                 }
388         }
389         return 0;
390 }
391
392 static ssize_t ppp_read(struct file *file, char __user *buf,
393                         size_t count, loff_t *ppos)
394 {
395         struct ppp_file *pf = file->private_data;
396         DECLARE_WAITQUEUE(wait, current);
397         ssize_t ret;
398         struct sk_buff *skb = NULL;
399
400         ret = count;
401
402         if (!pf)
403                 return -ENXIO;
404         add_wait_queue(&pf->rwait, &wait);
405         for (;;) {
406                 set_current_state(TASK_INTERRUPTIBLE);
407                 skb = skb_dequeue(&pf->rq);
408                 if (skb)
409                         break;
410                 ret = 0;
411                 if (pf->dead)
412                         break;
413                 if (pf->kind == INTERFACE) {
414                         /*
415                          * Return 0 (EOF) on an interface that has no
416                          * channels connected, unless it is looping
417                          * network traffic (demand mode).
418                          */
419                         struct ppp *ppp = PF_TO_PPP(pf);
420                         if (ppp->n_channels == 0
421                             && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
422                                 break;
423                 }
424                 ret = -EAGAIN;
425                 if (file->f_flags & O_NONBLOCK)
426                         break;
427                 ret = -ERESTARTSYS;
428                 if (signal_pending(current))
429                         break;
430                 schedule();
431         }
432         set_current_state(TASK_RUNNING);
433         remove_wait_queue(&pf->rwait, &wait);
434
435         if (!skb)
436                 goto out;
437
438         ret = -EOVERFLOW;
439         if (skb->len > count)
440                 goto outf;
441         ret = -EFAULT;
442         if (copy_to_user(buf, skb->data, skb->len))
443                 goto outf;
444         ret = skb->len;
445
446  outf:
447         kfree_skb(skb);
448  out:
449         return ret;
450 }
451
452 static ssize_t ppp_write(struct file *file, const char __user *buf,
453                          size_t count, loff_t *ppos)
454 {
455         struct ppp_file *pf = file->private_data;
456         struct sk_buff *skb;
457         ssize_t ret;
458
459         if (!pf)
460                 return -ENXIO;
461         ret = -ENOMEM;
462         skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
463         if (!skb)
464                 goto out;
465         skb_reserve(skb, pf->hdrlen);
466         ret = -EFAULT;
467         if (copy_from_user(skb_put(skb, count), buf, count)) {
468                 kfree_skb(skb);
469                 goto out;
470         }
471
472         skb_queue_tail(&pf->xq, skb);
473
474         switch (pf->kind) {
475         case INTERFACE:
476                 ppp_xmit_process(PF_TO_PPP(pf));
477                 break;
478         case CHANNEL:
479                 ppp_channel_push(PF_TO_CHANNEL(pf));
480                 break;
481         }
482
483         ret = count;
484
485  out:
486         return ret;
487 }
488
489 /* No kernel lock - fine */
490 static unsigned int ppp_poll(struct file *file, poll_table *wait)
491 {
492         struct ppp_file *pf = file->private_data;
493         unsigned int mask;
494
495         if (!pf)
496                 return 0;
497         poll_wait(file, &pf->rwait, wait);
498         mask = POLLOUT | POLLWRNORM;
499         if (skb_peek(&pf->rq))
500                 mask |= POLLIN | POLLRDNORM;
501         if (pf->dead)
502                 mask |= POLLHUP;
503         else if (pf->kind == INTERFACE) {
504                 /* see comment in ppp_read */
505                 struct ppp *ppp = PF_TO_PPP(pf);
506                 if (ppp->n_channels == 0
507                     && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
508                         mask |= POLLIN | POLLRDNORM;
509         }
510
511         return mask;
512 }
513
514 #ifdef CONFIG_PPP_FILTER
515 static int get_filter(void __user *arg, struct sock_filter **p)
516 {
517         struct sock_fprog uprog;
518         struct sock_filter *code = NULL;
519         int len, err;
520
521         if (copy_from_user(&uprog, arg, sizeof(uprog)))
522                 return -EFAULT;
523
524         if (!uprog.len) {
525                 *p = NULL;
526                 return 0;
527         }
528
529         len = uprog.len * sizeof(struct sock_filter);
530         code = kmalloc(len, GFP_KERNEL);
531         if (code == NULL)
532                 return -ENOMEM;
533
534         if (copy_from_user(code, uprog.filter, len)) {
535                 kfree(code);
536                 return -EFAULT;
537         }
538
539         err = sk_chk_filter(code, uprog.len);
540         if (err) {
541                 kfree(code);
542                 return err;
543         }
544
545         *p = code;
546         return uprog.len;
547 }
548 #endif /* CONFIG_PPP_FILTER */
549
550 static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
551 {
552         struct ppp_file *pf = file->private_data;
553         struct ppp *ppp;
554         int err = -EFAULT, val, val2, i;
555         struct ppp_idle idle;
556         struct npioctl npi;
557         int unit, cflags;
558         struct slcompress *vj;
559         void __user *argp = (void __user *)arg;
560         int __user *p = argp;
561
562         if (!pf)
563                 return ppp_unattached_ioctl(pf, file, cmd, arg);
564
565         if (cmd == PPPIOCDETACH) {
566                 /*
567                  * We have to be careful here... if the file descriptor
568                  * has been dup'd, we could have another process in the
569                  * middle of a poll using the same file *, so we had
570                  * better not free the interface data structures -
571                  * instead we fail the ioctl.  Even in this case, we
572                  * shut down the interface if we are the owner of it.
573                  * Actually, we should get rid of PPPIOCDETACH, userland
574                  * (i.e. pppd) could achieve the same effect by closing
575                  * this fd and reopening /dev/ppp.
576                  */
577                 err = -EINVAL;
578                 lock_kernel();
579                 if (pf->kind == INTERFACE) {
580                         ppp = PF_TO_PPP(pf);
581                         if (file == ppp->owner)
582                                 ppp_shutdown_interface(ppp);
583                 }
584                 if (atomic_long_read(&file->f_count) <= 2) {
585                         ppp_release(NULL, file);
586                         err = 0;
587                 } else
588                         printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%ld\n",
589                                atomic_long_read(&file->f_count));
590                 unlock_kernel();
591                 return err;
592         }
593
594         if (pf->kind == CHANNEL) {
595                 struct channel *pch;
596                 struct ppp_channel *chan;
597
598                 lock_kernel();
599                 pch = PF_TO_CHANNEL(pf);
600
601                 switch (cmd) {
602                 case PPPIOCCONNECT:
603                         if (get_user(unit, p))
604                                 break;
605                         err = ppp_connect_channel(pch, unit);
606                         break;
607
608                 case PPPIOCDISCONN:
609                         err = ppp_disconnect_channel(pch);
610                         break;
611
612                 default:
613                         down_read(&pch->chan_sem);
614                         chan = pch->chan;
615                         err = -ENOTTY;
616                         if (chan && chan->ops->ioctl)
617                                 err = chan->ops->ioctl(chan, cmd, arg);
618                         up_read(&pch->chan_sem);
619                 }
620                 unlock_kernel();
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         lock_kernel();
631         ppp = PF_TO_PPP(pf);
632         switch (cmd) {
633         case PPPIOCSMRU:
634                 if (get_user(val, p))
635                         break;
636                 ppp->mru = val;
637                 err = 0;
638                 break;
639
640         case PPPIOCSFLAGS:
641                 if (get_user(val, p))
642                         break;
643                 ppp_lock(ppp);
644                 cflags = ppp->flags & ~val;
645                 ppp->flags = val & SC_FLAG_BITS;
646                 ppp_unlock(ppp);
647                 if (cflags & SC_CCP_OPEN)
648                         ppp_ccp_closed(ppp);
649                 err = 0;
650                 break;
651
652         case PPPIOCGFLAGS:
653                 val = ppp->flags | ppp->xstate | ppp->rstate;
654                 if (put_user(val, p))
655                         break;
656                 err = 0;
657                 break;
658
659         case PPPIOCSCOMPRESS:
660                 err = ppp_set_compress(ppp, arg);
661                 break;
662
663         case PPPIOCGUNIT:
664                 if (put_user(ppp->file.index, p))
665                         break;
666                 err = 0;
667                 break;
668
669         case PPPIOCSDEBUG:
670                 if (get_user(val, p))
671                         break;
672                 ppp->debug = val;
673                 err = 0;
674                 break;
675
676         case PPPIOCGDEBUG:
677                 if (put_user(ppp->debug, p))
678                         break;
679                 err = 0;
680                 break;
681
682         case PPPIOCGIDLE:
683                 idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
684                 idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
685                 if (copy_to_user(argp, &idle, sizeof(idle)))
686                         break;
687                 err = 0;
688                 break;
689
690         case PPPIOCSMAXCID:
691                 if (get_user(val, p))
692                         break;
693                 val2 = 15;
694                 if ((val >> 16) != 0) {
695                         val2 = val >> 16;
696                         val &= 0xffff;
697                 }
698                 vj = slhc_init(val2+1, val+1);
699                 if (!vj) {
700                         printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
701                         err = -ENOMEM;
702                         break;
703                 }
704                 ppp_lock(ppp);
705                 if (ppp->vj)
706                         slhc_free(ppp->vj);
707                 ppp->vj = vj;
708                 ppp_unlock(ppp);
709                 err = 0;
710                 break;
711
712         case PPPIOCGNPMODE:
713         case PPPIOCSNPMODE:
714                 if (copy_from_user(&npi, argp, sizeof(npi)))
715                         break;
716                 err = proto_to_npindex(npi.protocol);
717                 if (err < 0)
718                         break;
719                 i = err;
720                 if (cmd == PPPIOCGNPMODE) {
721                         err = -EFAULT;
722                         npi.mode = ppp->npmode[i];
723                         if (copy_to_user(argp, &npi, sizeof(npi)))
724                                 break;
725                 } else {
726                         ppp->npmode[i] = npi.mode;
727                         /* we may be able to transmit more packets now (??) */
728                         netif_wake_queue(ppp->dev);
729                 }
730                 err = 0;
731                 break;
732
733 #ifdef CONFIG_PPP_FILTER
734         case PPPIOCSPASS:
735         {
736                 struct sock_filter *code;
737                 err = get_filter(argp, &code);
738                 if (err >= 0) {
739                         ppp_lock(ppp);
740                         kfree(ppp->pass_filter);
741                         ppp->pass_filter = code;
742                         ppp->pass_len = err;
743                         ppp_unlock(ppp);
744                         err = 0;
745                 }
746                 break;
747         }
748         case PPPIOCSACTIVE:
749         {
750                 struct sock_filter *code;
751                 err = get_filter(argp, &code);
752                 if (err >= 0) {
753                         ppp_lock(ppp);
754                         kfree(ppp->active_filter);
755                         ppp->active_filter = code;
756                         ppp->active_len = err;
757                         ppp_unlock(ppp);
758                         err = 0;
759                 }
760                 break;
761         }
762 #endif /* CONFIG_PPP_FILTER */
763
764 #ifdef CONFIG_PPP_MULTILINK
765         case PPPIOCSMRRU:
766                 if (get_user(val, p))
767                         break;
768                 ppp_recv_lock(ppp);
769                 ppp->mrru = val;
770                 ppp_recv_unlock(ppp);
771                 err = 0;
772                 break;
773 #endif /* CONFIG_PPP_MULTILINK */
774
775         default:
776                 err = -ENOTTY;
777         }
778         unlock_kernel();
779         return err;
780 }
781
782 static int ppp_unattached_ioctl(struct ppp_file *pf, struct file *file,
783                                 unsigned int cmd, unsigned long arg)
784 {
785         int unit, err = -EFAULT;
786         struct ppp *ppp;
787         struct channel *chan;
788         int __user *p = (int __user *)arg;
789
790         lock_kernel();
791         switch (cmd) {
792         case PPPIOCNEWUNIT:
793                 /* Create a new ppp unit */
794                 if (get_user(unit, p))
795                         break;
796                 ppp = ppp_create_interface(unit, &err);
797                 if (!ppp)
798                         break;
799                 file->private_data = &ppp->file;
800                 ppp->owner = file;
801                 err = -EFAULT;
802                 if (put_user(ppp->file.index, p))
803                         break;
804                 err = 0;
805                 break;
806
807         case PPPIOCATTACH:
808                 /* Attach to an existing ppp unit */
809                 if (get_user(unit, p))
810                         break;
811                 mutex_lock(&all_ppp_mutex);
812                 err = -ENXIO;
813                 ppp = ppp_find_unit(unit);
814                 if (ppp) {
815                         atomic_inc(&ppp->file.refcnt);
816                         file->private_data = &ppp->file;
817                         err = 0;
818                 }
819                 mutex_unlock(&all_ppp_mutex);
820                 break;
821
822         case PPPIOCATTCHAN:
823                 if (get_user(unit, p))
824                         break;
825                 spin_lock_bh(&all_channels_lock);
826                 err = -ENXIO;
827                 chan = ppp_find_channel(unit);
828                 if (chan) {
829                         atomic_inc(&chan->file.refcnt);
830                         file->private_data = &chan->file;
831                         err = 0;
832                 }
833                 spin_unlock_bh(&all_channels_lock);
834                 break;
835
836         default:
837                 err = -ENOTTY;
838         }
839         unlock_kernel();
840         return err;
841 }
842
843 static const struct file_operations ppp_device_fops = {
844         .owner          = THIS_MODULE,
845         .read           = ppp_read,
846         .write          = ppp_write,
847         .poll           = ppp_poll,
848         .unlocked_ioctl = ppp_ioctl,
849         .open           = ppp_open,
850         .release        = ppp_release
851 };
852
853 #define PPP_MAJOR       108
854
855 /* Called at boot time if ppp is compiled into the kernel,
856    or at module load time (from init_module) if compiled as a module. */
857 static int __init ppp_init(void)
858 {
859         int err;
860
861         printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");
862         err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
863         if (!err) {
864                 ppp_class = class_create(THIS_MODULE, "ppp");
865                 if (IS_ERR(ppp_class)) {
866                         err = PTR_ERR(ppp_class);
867                         goto out_chrdev;
868                 }
869                 device_create_drvdata(ppp_class, NULL, MKDEV(PPP_MAJOR, 0),
870                                       NULL, "ppp");
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_chrdev:
879         unregister_chrdev(PPP_MAJOR, "ppp");
880         goto out;
881 }
882
883 /*
884  * Network interface unit routines.
885  */
886 static int
887 ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
888 {
889         struct ppp *ppp = (struct ppp *) dev->priv;
890         int npi, proto;
891         unsigned char *pp;
892
893         npi = ethertype_to_npindex(ntohs(skb->protocol));
894         if (npi < 0)
895                 goto outf;
896
897         /* Drop, accept or reject the packet */
898         switch (ppp->npmode[npi]) {
899         case NPMODE_PASS:
900                 break;
901         case NPMODE_QUEUE:
902                 /* it would be nice to have a way to tell the network
903                    system to queue this one up for later. */
904                 goto outf;
905         case NPMODE_DROP:
906         case NPMODE_ERROR:
907                 goto outf;
908         }
909
910         /* Put the 2-byte PPP protocol number on the front,
911            making sure there is room for the address and control fields. */
912         if (skb_cow_head(skb, PPP_HDRLEN))
913                 goto outf;
914
915         pp = skb_push(skb, 2);
916         proto = npindex_to_proto[npi];
917         pp[0] = proto >> 8;
918         pp[1] = proto;
919
920         netif_stop_queue(dev);
921         skb_queue_tail(&ppp->file.xq, skb);
922         ppp_xmit_process(ppp);
923         return 0;
924
925  outf:
926         kfree_skb(skb);
927         ++ppp->dev->stats.tx_dropped;
928         return 0;
929 }
930
931 static int
932 ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
933 {
934         struct ppp *ppp = dev->priv;
935         int err = -EFAULT;
936         void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
937         struct ppp_stats stats;
938         struct ppp_comp_stats cstats;
939         char *vers;
940
941         switch (cmd) {
942         case SIOCGPPPSTATS:
943                 ppp_get_stats(ppp, &stats);
944                 if (copy_to_user(addr, &stats, sizeof(stats)))
945                         break;
946                 err = 0;
947                 break;
948
949         case SIOCGPPPCSTATS:
950                 memset(&cstats, 0, sizeof(cstats));
951                 if (ppp->xc_state)
952                         ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
953                 if (ppp->rc_state)
954                         ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
955                 if (copy_to_user(addr, &cstats, sizeof(cstats)))
956                         break;
957                 err = 0;
958                 break;
959
960         case SIOCGPPPVER:
961                 vers = PPP_VERSION;
962                 if (copy_to_user(addr, vers, strlen(vers) + 1))
963                         break;
964                 err = 0;
965                 break;
966
967         default:
968                 err = -EINVAL;
969         }
970
971         return err;
972 }
973
974 static void ppp_setup(struct net_device *dev)
975 {
976         dev->hard_header_len = PPP_HDRLEN;
977         dev->mtu = PPP_MTU;
978         dev->addr_len = 0;
979         dev->tx_queue_len = 3;
980         dev->type = ARPHRD_PPP;
981         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
982 }
983
984 /*
985  * Transmit-side routines.
986  */
987
988 /*
989  * Called to do any work queued up on the transmit side
990  * that can now be done.
991  */
992 static void
993 ppp_xmit_process(struct ppp *ppp)
994 {
995         struct sk_buff *skb;
996
997         ppp_xmit_lock(ppp);
998         if (ppp->dev) {
999                 ppp_push(ppp);
1000                 while (!ppp->xmit_pending
1001                        && (skb = skb_dequeue(&ppp->file.xq)))
1002                         ppp_send_frame(ppp, skb);
1003                 /* If there's no work left to do, tell the core net
1004                    code that we can accept some more. */
1005                 if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
1006                         netif_wake_queue(ppp->dev);
1007         }
1008         ppp_xmit_unlock(ppp);
1009 }
1010
1011 static inline struct sk_buff *
1012 pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
1013 {
1014         struct sk_buff *new_skb;
1015         int len;
1016         int new_skb_size = ppp->dev->mtu +
1017                 ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
1018         int compressor_skb_size = ppp->dev->mtu +
1019                 ppp->xcomp->comp_extra + PPP_HDRLEN;
1020         new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
1021         if (!new_skb) {
1022                 if (net_ratelimit())
1023                         printk(KERN_ERR "PPP: no memory (comp pkt)\n");
1024                 return NULL;
1025         }
1026         if (ppp->dev->hard_header_len > PPP_HDRLEN)
1027                 skb_reserve(new_skb,
1028                             ppp->dev->hard_header_len - PPP_HDRLEN);
1029
1030         /* compressor still expects A/C bytes in hdr */
1031         len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
1032                                    new_skb->data, skb->len + 2,
1033                                    compressor_skb_size);
1034         if (len > 0 && (ppp->flags & SC_CCP_UP)) {
1035                 kfree_skb(skb);
1036                 skb = new_skb;
1037                 skb_put(skb, len);
1038                 skb_pull(skb, 2);       /* pull off A/C bytes */
1039         } else if (len == 0) {
1040                 /* didn't compress, or CCP not up yet */
1041                 kfree_skb(new_skb);
1042                 new_skb = skb;
1043         } else {
1044                 /*
1045                  * (len < 0)
1046                  * MPPE requires that we do not send unencrypted
1047                  * frames.  The compressor will return -1 if we
1048                  * should drop the frame.  We cannot simply test
1049                  * the compress_proto because MPPE and MPPC share
1050                  * the same number.
1051                  */
1052                 if (net_ratelimit())
1053                         printk(KERN_ERR "ppp: compressor dropped pkt\n");
1054                 kfree_skb(skb);
1055                 kfree_skb(new_skb);
1056                 new_skb = NULL;
1057         }
1058         return new_skb;
1059 }
1060
1061 /*
1062  * Compress and send a frame.
1063  * The caller should have locked the xmit path,
1064  * and xmit_pending should be 0.
1065  */
1066 static void
1067 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
1068 {
1069         int proto = PPP_PROTO(skb);
1070         struct sk_buff *new_skb;
1071         int len;
1072         unsigned char *cp;
1073
1074         if (proto < 0x8000) {
1075 #ifdef CONFIG_PPP_FILTER
1076                 /* check if we should pass this packet */
1077                 /* the filter instructions are constructed assuming
1078                    a four-byte PPP header on each packet */
1079                 *skb_push(skb, 2) = 1;
1080                 if (ppp->pass_filter
1081                     && sk_run_filter(skb, ppp->pass_filter,
1082                                      ppp->pass_len) == 0) {
1083                         if (ppp->debug & 1)
1084                                 printk(KERN_DEBUG "PPP: outbound frame not passed\n");
1085                         kfree_skb(skb);
1086                         return;
1087                 }
1088                 /* if this packet passes the active filter, record the time */
1089                 if (!(ppp->active_filter
1090                       && sk_run_filter(skb, ppp->active_filter,
1091                                        ppp->active_len) == 0))
1092                         ppp->last_xmit = jiffies;
1093                 skb_pull(skb, 2);
1094 #else
1095                 /* for data packets, record the time */
1096                 ppp->last_xmit = jiffies;
1097 #endif /* CONFIG_PPP_FILTER */
1098         }
1099
1100         ++ppp->dev->stats.tx_packets;
1101         ppp->dev->stats.tx_bytes += skb->len - 2;
1102
1103         switch (proto) {
1104         case PPP_IP:
1105                 if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
1106                         break;
1107                 /* try to do VJ TCP header compression */
1108                 new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
1109                                     GFP_ATOMIC);
1110                 if (!new_skb) {
1111                         printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
1112                         goto drop;
1113                 }
1114                 skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
1115                 cp = skb->data + 2;
1116                 len = slhc_compress(ppp->vj, cp, skb->len - 2,
1117                                     new_skb->data + 2, &cp,
1118                                     !(ppp->flags & SC_NO_TCP_CCID));
1119                 if (cp == skb->data + 2) {
1120                         /* didn't compress */
1121                         kfree_skb(new_skb);
1122                 } else {
1123                         if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
1124                                 proto = PPP_VJC_COMP;
1125                                 cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
1126                         } else {
1127                                 proto = PPP_VJC_UNCOMP;
1128                                 cp[0] = skb->data[2];
1129                         }
1130                         kfree_skb(skb);
1131                         skb = new_skb;
1132                         cp = skb_put(skb, len + 2);
1133                         cp[0] = 0;
1134                         cp[1] = proto;
1135                 }
1136                 break;
1137
1138         case PPP_CCP:
1139                 /* peek at outbound CCP frames */
1140                 ppp_ccp_peek(ppp, skb, 0);
1141                 break;
1142         }
1143
1144         /* try to do packet compression */
1145         if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state
1146             && proto != PPP_LCP && proto != PPP_CCP) {
1147                 if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
1148                         if (net_ratelimit())
1149                                 printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
1150                         goto drop;
1151                 }
1152                 skb = pad_compress_skb(ppp, skb);
1153                 if (!skb)
1154                         goto drop;
1155         }
1156
1157         /*
1158          * If we are waiting for traffic (demand dialling),
1159          * queue it up for pppd to receive.
1160          */
1161         if (ppp->flags & SC_LOOP_TRAFFIC) {
1162                 if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
1163                         goto drop;
1164                 skb_queue_tail(&ppp->file.rq, skb);
1165                 wake_up_interruptible(&ppp->file.rwait);
1166                 return;
1167         }
1168
1169         ppp->xmit_pending = skb;
1170         ppp_push(ppp);
1171         return;
1172
1173  drop:
1174         if (skb)
1175                 kfree_skb(skb);
1176         ++ppp->dev->stats.tx_errors;
1177 }
1178
1179 /*
1180  * Try to send the frame in xmit_pending.
1181  * The caller should have the xmit path locked.
1182  */
1183 static void
1184 ppp_push(struct ppp *ppp)
1185 {
1186         struct list_head *list;
1187         struct channel *pch;
1188         struct sk_buff *skb = ppp->xmit_pending;
1189
1190         if (!skb)
1191                 return;
1192
1193         list = &ppp->channels;
1194         if (list_empty(list)) {
1195                 /* nowhere to send the packet, just drop it */
1196                 ppp->xmit_pending = NULL;
1197                 kfree_skb(skb);
1198                 return;
1199         }
1200
1201         if ((ppp->flags & SC_MULTILINK) == 0) {
1202                 /* not doing multilink: send it down the first channel */
1203                 list = list->next;
1204                 pch = list_entry(list, struct channel, clist);
1205
1206                 spin_lock_bh(&pch->downl);
1207                 if (pch->chan) {
1208                         if (pch->chan->ops->start_xmit(pch->chan, skb))
1209                                 ppp->xmit_pending = NULL;
1210                 } else {
1211                         /* channel got unregistered */
1212                         kfree_skb(skb);
1213                         ppp->xmit_pending = NULL;
1214                 }
1215                 spin_unlock_bh(&pch->downl);
1216                 return;
1217         }
1218
1219 #ifdef CONFIG_PPP_MULTILINK
1220         /* Multilink: fragment the packet over as many links
1221            as can take the packet at the moment. */
1222         if (!ppp_mp_explode(ppp, skb))
1223                 return;
1224 #endif /* CONFIG_PPP_MULTILINK */
1225
1226         ppp->xmit_pending = NULL;
1227         kfree_skb(skb);
1228 }
1229
1230 #ifdef CONFIG_PPP_MULTILINK
1231 /*
1232  * Divide a packet to be transmitted into fragments and
1233  * send them out the individual links.
1234  */
1235 static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1236 {
1237         int len, fragsize;
1238         int i, bits, hdrlen, mtu;
1239         int flen;
1240         int navail, nfree;
1241         int nbigger;
1242         unsigned char *p, *q;
1243         struct list_head *list;
1244         struct channel *pch;
1245         struct sk_buff *frag;
1246         struct ppp_channel *chan;
1247
1248         nfree = 0;      /* # channels which have no packet already queued */
1249         navail = 0;     /* total # of usable channels (not deregistered) */
1250         hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1251         i = 0;
1252         list_for_each_entry(pch, &ppp->channels, clist) {
1253                 navail += pch->avail = (pch->chan != NULL);
1254                 if (pch->avail) {
1255                         if (skb_queue_empty(&pch->file.xq) ||
1256                             !pch->had_frag) {
1257                                 pch->avail = 2;
1258                                 ++nfree;
1259                         }
1260                         if (!pch->had_frag && i < ppp->nxchan)
1261                                 ppp->nxchan = i;
1262                 }
1263                 ++i;
1264         }
1265
1266         /*
1267          * Don't start sending this packet unless at least half of
1268          * the channels are free.  This gives much better TCP
1269          * performance if we have a lot of channels.
1270          */
1271         if (nfree == 0 || nfree < navail / 2)
1272                 return 0;       /* can't take now, leave it in xmit_pending */
1273
1274         /* Do protocol field compression (XXX this should be optional) */
1275         p = skb->data;
1276         len = skb->len;
1277         if (*p == 0) {
1278                 ++p;
1279                 --len;
1280         }
1281
1282         /*
1283          * Decide on fragment size.
1284          * We create a fragment for each free channel regardless of
1285          * how small they are (i.e. even 0 length) in order to minimize
1286          * the time that it will take to detect when a channel drops
1287          * a fragment.
1288          */
1289         fragsize = len;
1290         if (nfree > 1)
1291                 fragsize = DIV_ROUND_UP(fragsize, nfree);
1292         /* nbigger channels get fragsize bytes, the rest get fragsize-1,
1293            except if nbigger==0, then they all get fragsize. */
1294         nbigger = len % nfree;
1295
1296         /* skip to the channel after the one we last used
1297            and start at that one */
1298         list = &ppp->channels;
1299         for (i = 0; i < ppp->nxchan; ++i) {
1300                 list = list->next;
1301                 if (list == &ppp->channels) {
1302                         i = 0;
1303                         break;
1304                 }
1305         }
1306
1307         /* create a fragment for each channel */
1308         bits = B;
1309         while (nfree > 0 || len > 0) {
1310                 list = list->next;
1311                 if (list == &ppp->channels) {
1312                         i = 0;
1313                         continue;
1314                 }
1315                 pch = list_entry(list, struct channel, clist);
1316                 ++i;
1317                 if (!pch->avail)
1318                         continue;
1319
1320                 /*
1321                  * Skip this channel if it has a fragment pending already and
1322                  * we haven't given a fragment to all of the free channels.
1323                  */
1324                 if (pch->avail == 1) {
1325                         if (nfree > 0)
1326                                 continue;
1327                 } else {
1328                         --nfree;
1329                         pch->avail = 1;
1330                 }
1331
1332                 /* check the channel's mtu and whether it is still attached. */
1333                 spin_lock_bh(&pch->downl);
1334                 if (pch->chan == NULL) {
1335                         /* can't use this channel, it's being deregistered */
1336                         spin_unlock_bh(&pch->downl);
1337                         pch->avail = 0;
1338                         if (--navail == 0)
1339                                 break;
1340                         continue;
1341                 }
1342
1343                 /*
1344                  * Create a fragment for this channel of
1345                  * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
1346                  * If mtu+2-hdrlen < 4, that is a ridiculously small
1347                  * MTU, so we use mtu = 2 + hdrlen.
1348                  */
1349                 if (fragsize > len)
1350                         fragsize = len;
1351                 flen = fragsize;
1352                 mtu = pch->chan->mtu + 2 - hdrlen;
1353                 if (mtu < 4)
1354                         mtu = 4;
1355                 if (flen > mtu)
1356                         flen = mtu;
1357                 if (flen == len && nfree == 0)
1358                         bits |= E;
1359                 frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
1360                 if (!frag)
1361                         goto noskb;
1362                 q = skb_put(frag, flen + hdrlen);
1363
1364                 /* make the MP header */
1365                 q[0] = PPP_MP >> 8;
1366                 q[1] = PPP_MP;
1367                 if (ppp->flags & SC_MP_XSHORTSEQ) {
1368                         q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
1369                         q[3] = ppp->nxseq;
1370                 } else {
1371                         q[2] = bits;
1372                         q[3] = ppp->nxseq >> 16;
1373                         q[4] = ppp->nxseq >> 8;
1374                         q[5] = ppp->nxseq;
1375                 }
1376
1377                 /*
1378                  * Copy the data in.
1379                  * Unfortunately there is a bug in older versions of
1380                  * the Linux PPP multilink reconstruction code where it
1381                  * drops 0-length fragments.  Therefore we make sure the
1382                  * fragment has at least one byte of data.  Any bytes
1383                  * we add in this situation will end up as padding on the
1384                  * end of the reconstructed packet.
1385                  */
1386                 if (flen == 0)
1387                         *skb_put(frag, 1) = 0;
1388                 else
1389                         memcpy(q + hdrlen, p, flen);
1390
1391                 /* try to send it down the channel */
1392                 chan = pch->chan;
1393                 if (!skb_queue_empty(&pch->file.xq) ||
1394                     !chan->ops->start_xmit(chan, frag))
1395                         skb_queue_tail(&pch->file.xq, frag);
1396                 pch->had_frag = 1;
1397                 p += flen;
1398                 len -= flen;
1399                 ++ppp->nxseq;
1400                 bits = 0;
1401                 spin_unlock_bh(&pch->downl);
1402
1403                 if (--nbigger == 0 && fragsize > 0)
1404                         --fragsize;
1405         }
1406         ppp->nxchan = i;
1407
1408         return 1;
1409
1410  noskb:
1411         spin_unlock_bh(&pch->downl);
1412         if (ppp->debug & 1)
1413                 printk(KERN_ERR "PPP: no memory (fragment)\n");
1414         ++ppp->dev->stats.tx_errors;
1415         ++ppp->nxseq;
1416         return 1;       /* abandon the frame */
1417 }
1418 #endif /* CONFIG_PPP_MULTILINK */
1419
1420 /*
1421  * Try to send data out on a channel.
1422  */
1423 static void
1424 ppp_channel_push(struct channel *pch)
1425 {
1426         struct sk_buff *skb;
1427         struct ppp *ppp;
1428
1429         spin_lock_bh(&pch->downl);
1430         if (pch->chan) {
1431                 while (!skb_queue_empty(&pch->file.xq)) {
1432                         skb = skb_dequeue(&pch->file.xq);
1433                         if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
1434                                 /* put the packet back and try again later */
1435                                 skb_queue_head(&pch->file.xq, skb);
1436                                 break;
1437                         }
1438                 }
1439         } else {
1440                 /* channel got deregistered */
1441                 skb_queue_purge(&pch->file.xq);
1442         }
1443         spin_unlock_bh(&pch->downl);
1444         /* see if there is anything from the attached unit to be sent */
1445         if (skb_queue_empty(&pch->file.xq)) {
1446                 read_lock_bh(&pch->upl);
1447                 ppp = pch->ppp;
1448                 if (ppp)
1449                         ppp_xmit_process(ppp);
1450                 read_unlock_bh(&pch->upl);
1451         }
1452 }
1453
1454 /*
1455  * Receive-side routines.
1456  */
1457
1458 /* misuse a few fields of the skb for MP reconstruction */
1459 #define sequence        priority
1460 #define BEbits          cb[0]
1461
1462 static inline void
1463 ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1464 {
1465         ppp_recv_lock(ppp);
1466         /* ppp->dev == 0 means interface is closing down */
1467         if (ppp->dev)
1468                 ppp_receive_frame(ppp, skb, pch);
1469         else
1470                 kfree_skb(skb);
1471         ppp_recv_unlock(ppp);
1472 }
1473
1474 void
1475 ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
1476 {
1477         struct channel *pch = chan->ppp;
1478         int proto;
1479
1480         if (!pch || skb->len == 0) {
1481                 kfree_skb(skb);
1482                 return;
1483         }
1484
1485         proto = PPP_PROTO(skb);
1486         read_lock_bh(&pch->upl);
1487         if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
1488                 /* put it on the channel queue */
1489                 skb_queue_tail(&pch->file.rq, skb);
1490                 /* drop old frames if queue too long */
1491                 while (pch->file.rq.qlen > PPP_MAX_RQLEN
1492                        && (skb = skb_dequeue(&pch->file.rq)))
1493                         kfree_skb(skb);
1494                 wake_up_interruptible(&pch->file.rwait);
1495         } else {
1496                 ppp_do_recv(pch->ppp, skb, pch);
1497         }
1498         read_unlock_bh(&pch->upl);
1499 }
1500
1501 /* Put a 0-length skb in the receive queue as an error indication */
1502 void
1503 ppp_input_error(struct ppp_channel *chan, int code)
1504 {
1505         struct channel *pch = chan->ppp;
1506         struct sk_buff *skb;
1507
1508         if (!pch)
1509                 return;
1510
1511         read_lock_bh(&pch->upl);
1512         if (pch->ppp) {
1513                 skb = alloc_skb(0, GFP_ATOMIC);
1514                 if (skb) {
1515                         skb->len = 0;           /* probably unnecessary */
1516                         skb->cb[0] = code;
1517                         ppp_do_recv(pch->ppp, skb, pch);
1518                 }
1519         }
1520         read_unlock_bh(&pch->upl);
1521 }
1522
1523 /*
1524  * We come in here to process a received frame.
1525  * The receive side of the ppp unit is locked.
1526  */
1527 static void
1528 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1529 {
1530         if (pskb_may_pull(skb, 2)) {
1531 #ifdef CONFIG_PPP_MULTILINK
1532                 /* XXX do channel-level decompression here */
1533                 if (PPP_PROTO(skb) == PPP_MP)
1534                         ppp_receive_mp_frame(ppp, skb, pch);
1535                 else
1536 #endif /* CONFIG_PPP_MULTILINK */
1537                         ppp_receive_nonmp_frame(ppp, skb);
1538                 return;
1539         }
1540
1541         if (skb->len > 0)
1542                 /* note: a 0-length skb is used as an error indication */
1543                 ++ppp->dev->stats.rx_length_errors;
1544
1545         kfree_skb(skb);
1546         ppp_receive_error(ppp);
1547 }
1548
1549 static void
1550 ppp_receive_error(struct ppp *ppp)
1551 {
1552         ++ppp->dev->stats.rx_errors;
1553         if (ppp->vj)
1554                 slhc_toss(ppp->vj);
1555 }
1556
1557 static void
1558 ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
1559 {
1560         struct sk_buff *ns;
1561         int proto, len, npi;
1562
1563         /*
1564          * Decompress the frame, if compressed.
1565          * Note that some decompressors need to see uncompressed frames
1566          * that come in as well as compressed frames.
1567          */
1568         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)
1569             && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
1570                 skb = ppp_decompress_frame(ppp, skb);
1571
1572         if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
1573                 goto err;
1574
1575         proto = PPP_PROTO(skb);
1576         switch (proto) {
1577         case PPP_VJC_COMP:
1578                 /* decompress VJ compressed packets */
1579                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1580                         goto err;
1581
1582                 if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
1583                         /* copy to a new sk_buff with more tailroom */
1584                         ns = dev_alloc_skb(skb->len + 128);
1585                         if (!ns) {
1586                                 printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
1587                                 goto err;
1588                         }
1589                         skb_reserve(ns, 2);
1590                         skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
1591                         kfree_skb(skb);
1592                         skb = ns;
1593                 }
1594                 else
1595                         skb->ip_summed = CHECKSUM_NONE;
1596
1597                 len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
1598                 if (len <= 0) {
1599                         printk(KERN_DEBUG "PPP: VJ decompression error\n");
1600                         goto err;
1601                 }
1602                 len += 2;
1603                 if (len > skb->len)
1604                         skb_put(skb, len - skb->len);
1605                 else if (len < skb->len)
1606                         skb_trim(skb, len);
1607                 proto = PPP_IP;
1608                 break;
1609
1610         case PPP_VJC_UNCOMP:
1611                 if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
1612                         goto err;
1613
1614                 /* Until we fix the decompressor need to make sure
1615                  * data portion is linear.
1616                  */
1617                 if (!pskb_may_pull(skb, skb->len))
1618                         goto err;
1619
1620                 if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
1621                         printk(KERN_ERR "PPP: VJ uncompressed error\n");
1622                         goto err;
1623                 }
1624                 proto = PPP_IP;
1625                 break;
1626
1627         case PPP_CCP:
1628                 ppp_ccp_peek(ppp, skb, 1);
1629                 break;
1630         }
1631
1632         ++ppp->dev->stats.rx_packets;
1633         ppp->dev->stats.rx_bytes += skb->len - 2;
1634
1635         npi = proto_to_npindex(proto);
1636         if (npi < 0) {
1637                 /* control or unknown frame - pass it to pppd */
1638                 skb_queue_tail(&ppp->file.rq, skb);
1639                 /* limit queue length by dropping old frames */
1640                 while (ppp->file.rq.qlen > PPP_MAX_RQLEN
1641                        && (skb = skb_dequeue(&ppp->file.rq)))
1642                         kfree_skb(skb);
1643                 /* wake up any process polling or blocking on read */
1644                 wake_up_interruptible(&ppp->file.rwait);
1645
1646         } else {
1647                 /* network protocol frame - give it to the kernel */
1648
1649 #ifdef CONFIG_PPP_FILTER
1650                 /* check if the packet passes the pass and active filters */
1651                 /* the filter instructions are constructed assuming
1652                    a four-byte PPP header on each packet */
1653                 if (ppp->pass_filter || ppp->active_filter) {
1654                         if (skb_cloned(skb) &&
1655                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
1656                                 goto err;
1657
1658                         *skb_push(skb, 2) = 0;
1659                         if (ppp->pass_filter
1660                             && sk_run_filter(skb, ppp->pass_filter,
1661                                              ppp->pass_len) == 0) {
1662                                 if (ppp->debug & 1)
1663                                         printk(KERN_DEBUG "PPP: inbound frame "
1664                                                "not passed\n");
1665                                 kfree_skb(skb);
1666                                 return;
1667                         }
1668                         if (!(ppp->active_filter
1669                               && sk_run_filter(skb, ppp->active_filter,
1670                                                ppp->active_len) == 0))
1671                                 ppp->last_recv = jiffies;
1672                         __skb_pull(skb, 2);
1673                 } else
1674 #endif /* CONFIG_PPP_FILTER */
1675                         ppp->last_recv = jiffies;
1676
1677                 if ((ppp->dev->flags & IFF_UP) == 0
1678                     || ppp->npmode[npi] != NPMODE_PASS) {
1679                         kfree_skb(skb);
1680                 } else {
1681                         /* chop off protocol */
1682                         skb_pull_rcsum(skb, 2);
1683                         skb->dev = ppp->dev;
1684                         skb->protocol = htons(npindex_to_ethertype[npi]);
1685                         skb_reset_mac_header(skb);
1686                         netif_rx(skb);
1687                         ppp->dev->last_rx = jiffies;
1688                 }
1689         }
1690         return;
1691
1692  err:
1693         kfree_skb(skb);
1694         ppp_receive_error(ppp);
1695 }
1696
1697 static struct sk_buff *
1698 ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
1699 {
1700         int proto = PPP_PROTO(skb);
1701         struct sk_buff *ns;
1702         int len;
1703
1704         /* Until we fix all the decompressor's need to make sure
1705          * data portion is linear.
1706          */
1707         if (!pskb_may_pull(skb, skb->len))
1708                 goto err;
1709
1710         if (proto == PPP_COMP) {
1711                 int obuff_size;
1712
1713                 switch(ppp->rcomp->compress_proto) {
1714                 case CI_MPPE:
1715                         obuff_size = ppp->mru + PPP_HDRLEN + 1;
1716                         break;
1717                 default:
1718                         obuff_size = ppp->mru + PPP_HDRLEN;
1719                         break;
1720                 }
1721
1722                 ns = dev_alloc_skb(obuff_size);
1723                 if (!ns) {
1724                         printk(KERN_ERR "ppp_decompress_frame: no memory\n");
1725                         goto err;
1726                 }
1727                 /* the decompressor still expects the A/C bytes in the hdr */
1728                 len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
1729                                 skb->len + 2, ns->data, obuff_size);
1730                 if (len < 0) {
1731                         /* Pass the compressed frame to pppd as an
1732                            error indication. */
1733                         if (len == DECOMP_FATALERROR)
1734                                 ppp->rstate |= SC_DC_FERROR;
1735                         kfree_skb(ns);
1736                         goto err;
1737                 }
1738
1739                 kfree_skb(skb);
1740                 skb = ns;
1741                 skb_put(skb, len);
1742                 skb_pull(skb, 2);       /* pull off the A/C bytes */
1743
1744         } else {
1745                 /* Uncompressed frame - pass to decompressor so it
1746                    can update its dictionary if necessary. */
1747                 if (ppp->rcomp->incomp)
1748                         ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
1749                                            skb->len + 2);
1750         }
1751
1752         return skb;
1753
1754  err:
1755         ppp->rstate |= SC_DC_ERROR;
1756         ppp_receive_error(ppp);
1757         return skb;
1758 }
1759
1760 #ifdef CONFIG_PPP_MULTILINK
1761 /*
1762  * Receive a multilink frame.
1763  * We put it on the reconstruction queue and then pull off
1764  * as many completed frames as we can.
1765  */
1766 static void
1767 ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
1768 {
1769         u32 mask, seq;
1770         struct channel *ch;
1771         int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
1772
1773         if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
1774                 goto err;               /* no good, throw it away */
1775
1776         /* Decode sequence number and begin/end bits */
1777         if (ppp->flags & SC_MP_SHORTSEQ) {
1778                 seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
1779                 mask = 0xfff;
1780         } else {
1781                 seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
1782                 mask = 0xffffff;
1783         }
1784         skb->BEbits = skb->data[2];
1785         skb_pull(skb, mphdrlen);        /* pull off PPP and MP headers */
1786
1787         /*
1788          * Do protocol ID decompression on the first fragment of each packet.
1789          */
1790         if ((skb->BEbits & B) && (skb->data[0] & 1))
1791                 *skb_push(skb, 1) = 0;
1792
1793         /*
1794          * Expand sequence number to 32 bits, making it as close
1795          * as possible to ppp->minseq.
1796          */
1797         seq |= ppp->minseq & ~mask;
1798         if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
1799                 seq += mask + 1;
1800         else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
1801                 seq -= mask + 1;        /* should never happen */
1802         skb->sequence = seq;
1803         pch->lastseq = seq;
1804
1805         /*
1806          * If this packet comes before the next one we were expecting,
1807          * drop it.
1808          */
1809         if (seq_before(seq, ppp->nextseq)) {
1810                 kfree_skb(skb);
1811                 ++ppp->dev->stats.rx_dropped;
1812                 ppp_receive_error(ppp);
1813                 return;
1814         }
1815
1816         /*
1817          * Reevaluate minseq, the minimum over all channels of the
1818          * last sequence number received on each channel.  Because of
1819          * the increasing sequence number rule, we know that any fragment
1820          * before `minseq' which hasn't arrived is never going to arrive.
1821          * The list of channels can't change because we have the receive
1822          * side of the ppp unit locked.
1823          */
1824         list_for_each_entry(ch, &ppp->channels, clist) {
1825                 if (seq_before(ch->lastseq, seq))
1826                         seq = ch->lastseq;
1827         }
1828         if (seq_before(ppp->minseq, seq))
1829                 ppp->minseq = seq;
1830
1831         /* Put the fragment on the reconstruction queue */
1832         ppp_mp_insert(ppp, skb);
1833
1834         /* If the queue is getting long, don't wait any longer for packets
1835            before the start of the queue. */
1836         if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN
1837             && seq_before(ppp->minseq, ppp->mrq.next->sequence))
1838                 ppp->minseq = ppp->mrq.next->sequence;
1839
1840         /* Pull completed packets off the queue and receive them. */
1841         while ((skb = ppp_mp_reconstruct(ppp)))
1842                 ppp_receive_nonmp_frame(ppp, skb);
1843
1844         return;
1845
1846  err:
1847         kfree_skb(skb);
1848         ppp_receive_error(ppp);
1849 }
1850
1851 /*
1852  * Insert a fragment on the MP reconstruction queue.
1853  * The queue is ordered by increasing sequence number.
1854  */
1855 static void
1856 ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
1857 {
1858         struct sk_buff *p;
1859         struct sk_buff_head *list = &ppp->mrq;
1860         u32 seq = skb->sequence;
1861
1862         /* N.B. we don't need to lock the list lock because we have the
1863            ppp unit receive-side lock. */
1864         for (p = list->next; p != (struct sk_buff *)list; p = p->next)
1865                 if (seq_before(seq, p->sequence))
1866                         break;
1867         __skb_insert(skb, p->prev, p, list);
1868 }
1869
1870 /*
1871  * Reconstruct a packet from the MP fragment queue.
1872  * We go through increasing sequence numbers until we find a
1873  * complete packet, or we get to the sequence number for a fragment
1874  * which hasn't arrived but might still do so.
1875  */
1876 static struct sk_buff *
1877 ppp_mp_reconstruct(struct ppp *ppp)
1878 {
1879         u32 seq = ppp->nextseq;
1880         u32 minseq = ppp->minseq;
1881         struct sk_buff_head *list = &ppp->mrq;
1882         struct sk_buff *p, *next;
1883         struct sk_buff *head, *tail;
1884         struct sk_buff *skb = NULL;
1885         int lost = 0, len = 0;
1886
1887         if (ppp->mrru == 0)     /* do nothing until mrru is set */
1888                 return NULL;
1889         head = list->next;
1890         tail = NULL;
1891         for (p = head; p != (struct sk_buff *) list; p = next) {
1892                 next = p->next;
1893                 if (seq_before(p->sequence, seq)) {
1894                         /* this can't happen, anyway ignore the skb */
1895                         printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
1896                                p->sequence, seq);
1897                         head = next;
1898                         continue;
1899                 }
1900                 if (p->sequence != seq) {
1901                         /* Fragment `seq' is missing.  If it is after
1902                            minseq, it might arrive later, so stop here. */
1903                         if (seq_after(seq, minseq))
1904                                 break;
1905                         /* Fragment `seq' is lost, keep going. */
1906                         lost = 1;
1907                         seq = seq_before(minseq, p->sequence)?
1908                                 minseq + 1: p->sequence;
1909                         next = p;
1910                         continue;
1911                 }
1912
1913                 /*
1914                  * At this point we know that all the fragments from
1915                  * ppp->nextseq to seq are either present or lost.
1916                  * Also, there are no complete packets in the queue
1917                  * that have no missing fragments and end before this
1918                  * fragment.
1919                  */
1920
1921                 /* B bit set indicates this fragment starts a packet */
1922                 if (p->BEbits & B) {
1923                         head = p;
1924                         lost = 0;
1925                         len = 0;
1926                 }
1927
1928                 len += p->len;
1929
1930                 /* Got a complete packet yet? */
1931                 if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
1932                         if (len > ppp->mrru + 2) {
1933                                 ++ppp->dev->stats.rx_length_errors;
1934                                 printk(KERN_DEBUG "PPP: reconstructed packet"
1935                                        " is too long (%d)\n", len);
1936                         } else if (p == head) {
1937                                 /* fragment is complete packet - reuse skb */
1938                                 tail = p;
1939                                 skb = skb_get(p);
1940                                 break;
1941                         } else if ((skb = dev_alloc_skb(len)) == NULL) {
1942                                 ++ppp->dev->stats.rx_missed_errors;
1943                                 printk(KERN_DEBUG "PPP: no memory for "
1944                                        "reconstructed packet");
1945                         } else {
1946                                 tail = p;
1947                                 break;
1948                         }
1949                         ppp->nextseq = seq + 1;
1950                 }
1951
1952                 /*
1953                  * If this is the ending fragment of a packet,
1954                  * and we haven't found a complete valid packet yet,
1955                  * we can discard up to and including this fragment.
1956                  */
1957                 if (p->BEbits & E)
1958                         head = next;
1959
1960                 ++seq;
1961         }
1962
1963         /* If we have a complete packet, copy it all into one skb. */
1964         if (tail != NULL) {
1965                 /* If we have discarded any fragments,
1966                    signal a receive error. */
1967                 if (head->sequence != ppp->nextseq) {
1968                         if (ppp->debug & 1)
1969                                 printk(KERN_DEBUG "  missed pkts %u..%u\n",
1970                                        ppp->nextseq, head->sequence-1);
1971                         ++ppp->dev->stats.rx_dropped;
1972                         ppp_receive_error(ppp);
1973                 }
1974
1975                 if (head != tail)
1976                         /* copy to a single skb */
1977                         for (p = head; p != tail->next; p = p->next)
1978                                 skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
1979                 ppp->nextseq = tail->sequence + 1;
1980                 head = tail->next;
1981         }
1982
1983         /* Discard all the skbuffs that we have copied the data out of
1984            or that we can't use. */
1985         while ((p = list->next) != head) {
1986                 __skb_unlink(p, list);
1987                 kfree_skb(p);
1988         }
1989
1990         return skb;
1991 }
1992 #endif /* CONFIG_PPP_MULTILINK */
1993
1994 /*
1995  * Channel interface.
1996  */
1997
1998 /*
1999  * Create a new, unattached ppp channel.
2000  */
2001 int
2002 ppp_register_channel(struct ppp_channel *chan)
2003 {
2004         struct channel *pch;
2005
2006         pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
2007         if (!pch)
2008                 return -ENOMEM;
2009         pch->ppp = NULL;
2010         pch->chan = chan;
2011         chan->ppp = pch;
2012         init_ppp_file(&pch->file, CHANNEL);
2013         pch->file.hdrlen = chan->hdrlen;
2014 #ifdef CONFIG_PPP_MULTILINK
2015         pch->lastseq = -1;
2016 #endif /* CONFIG_PPP_MULTILINK */
2017         init_rwsem(&pch->chan_sem);
2018         spin_lock_init(&pch->downl);
2019         rwlock_init(&pch->upl);
2020         spin_lock_bh(&all_channels_lock);
2021         pch->file.index = ++last_channel_index;
2022         list_add(&pch->list, &new_channels);
2023         atomic_inc(&channel_count);
2024         spin_unlock_bh(&all_channels_lock);
2025         return 0;
2026 }
2027
2028 /*
2029  * Return the index of a channel.
2030  */
2031 int ppp_channel_index(struct ppp_channel *chan)
2032 {
2033         struct channel *pch = chan->ppp;
2034
2035         if (pch)
2036                 return pch->file.index;
2037         return -1;
2038 }
2039
2040 /*
2041  * Return the PPP unit number to which a channel is connected.
2042  */
2043 int ppp_unit_number(struct ppp_channel *chan)
2044 {
2045         struct channel *pch = chan->ppp;
2046         int unit = -1;
2047
2048         if (pch) {
2049                 read_lock_bh(&pch->upl);
2050                 if (pch->ppp)
2051                         unit = pch->ppp->file.index;
2052                 read_unlock_bh(&pch->upl);
2053         }
2054         return unit;
2055 }
2056
2057 /*
2058  * Disconnect a channel from the generic layer.
2059  * This must be called in process context.
2060  */
2061 void
2062 ppp_unregister_channel(struct ppp_channel *chan)
2063 {
2064         struct channel *pch = chan->ppp;
2065
2066         if (!pch)
2067                 return;         /* should never happen */
2068         chan->ppp = NULL;
2069
2070         /*
2071          * This ensures that we have returned from any calls into the
2072          * the channel's start_xmit or ioctl routine before we proceed.
2073          */
2074         down_write(&pch->chan_sem);
2075         spin_lock_bh(&pch->downl);
2076         pch->chan = NULL;
2077         spin_unlock_bh(&pch->downl);
2078         up_write(&pch->chan_sem);
2079         ppp_disconnect_channel(pch);
2080         spin_lock_bh(&all_channels_lock);
2081         list_del(&pch->list);
2082         spin_unlock_bh(&all_channels_lock);
2083         pch->file.dead = 1;
2084         wake_up_interruptible(&pch->file.rwait);
2085         if (atomic_dec_and_test(&pch->file.refcnt))
2086                 ppp_destroy_channel(pch);
2087 }
2088
2089 /*
2090  * Callback from a channel when it can accept more to transmit.
2091  * This should be called at BH/softirq level, not interrupt level.
2092  */
2093 void
2094 ppp_output_wakeup(struct ppp_channel *chan)
2095 {
2096         struct channel *pch = chan->ppp;
2097
2098         if (!pch)
2099                 return;
2100         ppp_channel_push(pch);
2101 }
2102
2103 /*
2104  * Compression control.
2105  */
2106
2107 /* Process the PPPIOCSCOMPRESS ioctl. */
2108 static int
2109 ppp_set_compress(struct ppp *ppp, unsigned long arg)
2110 {
2111         int err;
2112         struct compressor *cp, *ocomp;
2113         struct ppp_option_data data;
2114         void *state, *ostate;
2115         unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];
2116
2117         err = -EFAULT;
2118         if (copy_from_user(&data, (void __user *) arg, sizeof(data))
2119             || (data.length <= CCP_MAX_OPTION_LENGTH
2120                 && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
2121                 goto out;
2122         err = -EINVAL;
2123         if (data.length > CCP_MAX_OPTION_LENGTH
2124             || ccp_option[1] < 2 || ccp_option[1] > data.length)
2125                 goto out;
2126
2127         cp = find_compressor(ccp_option[0]);
2128 #ifdef CONFIG_KMOD
2129         if (!cp) {
2130                 request_module("ppp-compress-%d", ccp_option[0]);
2131                 cp = find_compressor(ccp_option[0]);
2132         }
2133 #endif /* CONFIG_KMOD */
2134         if (!cp)
2135                 goto out;
2136
2137         err = -ENOBUFS;
2138         if (data.transmit) {
2139                 state = cp->comp_alloc(ccp_option, data.length);
2140                 if (state) {
2141                         ppp_xmit_lock(ppp);
2142                         ppp->xstate &= ~SC_COMP_RUN;
2143                         ocomp = ppp->xcomp;
2144                         ostate = ppp->xc_state;
2145                         ppp->xcomp = cp;
2146                         ppp->xc_state = state;
2147                         ppp_xmit_unlock(ppp);
2148                         if (ostate) {
2149                                 ocomp->comp_free(ostate);
2150                                 module_put(ocomp->owner);
2151                         }
2152                         err = 0;
2153                 } else
2154                         module_put(cp->owner);
2155
2156         } else {
2157                 state = cp->decomp_alloc(ccp_option, data.length);
2158                 if (state) {
2159                         ppp_recv_lock(ppp);
2160                         ppp->rstate &= ~SC_DECOMP_RUN;
2161                         ocomp = ppp->rcomp;
2162                         ostate = ppp->rc_state;
2163                         ppp->rcomp = cp;
2164                         ppp->rc_state = state;
2165                         ppp_recv_unlock(ppp);
2166                         if (ostate) {
2167                                 ocomp->decomp_free(ostate);
2168                                 module_put(ocomp->owner);
2169                         }
2170                         err = 0;
2171                 } else
2172                         module_put(cp->owner);
2173         }
2174
2175  out:
2176         return err;
2177 }
2178
2179 /*
2180  * Look at a CCP packet and update our state accordingly.
2181  * We assume the caller has the xmit or recv path locked.
2182  */
2183 static void
2184 ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
2185 {
2186         unsigned char *dp;
2187         int len;
2188
2189         if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
2190                 return; /* no header */
2191         dp = skb->data + 2;
2192
2193         switch (CCP_CODE(dp)) {
2194         case CCP_CONFREQ:
2195
2196                 /* A ConfReq starts negotiation of compression
2197                  * in one direction of transmission,
2198                  * and hence brings it down...but which way?
2199                  *
2200                  * Remember:
2201                  * A ConfReq indicates what the sender would like to receive
2202                  */
2203                 if(inbound)
2204                         /* He is proposing what I should send */
2205                         ppp->xstate &= ~SC_COMP_RUN;
2206                 else
2207                         /* I am proposing to what he should send */
2208                         ppp->rstate &= ~SC_DECOMP_RUN;
2209
2210                 break;
2211
2212         case CCP_TERMREQ:
2213         case CCP_TERMACK:
2214                 /*
2215                  * CCP is going down, both directions of transmission
2216                  */
2217                 ppp->rstate &= ~SC_DECOMP_RUN;
2218                 ppp->xstate &= ~SC_COMP_RUN;
2219                 break;
2220
2221         case CCP_CONFACK:
2222                 if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
2223                         break;
2224                 len = CCP_LENGTH(dp);
2225                 if (!pskb_may_pull(skb, len + 2))
2226                         return;         /* too short */
2227                 dp += CCP_HDRLEN;
2228                 len -= CCP_HDRLEN;
2229                 if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
2230                         break;
2231                 if (inbound) {
2232                         /* we will start receiving compressed packets */
2233                         if (!ppp->rc_state)
2234                                 break;
2235                         if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
2236                                         ppp->file.index, 0, ppp->mru, ppp->debug)) {
2237                                 ppp->rstate |= SC_DECOMP_RUN;
2238                                 ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
2239                         }
2240                 } else {
2241                         /* we will soon start sending compressed packets */
2242                         if (!ppp->xc_state)
2243                                 break;
2244                         if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
2245                                         ppp->file.index, 0, ppp->debug))
2246                                 ppp->xstate |= SC_COMP_RUN;
2247                 }
2248                 break;
2249
2250         case CCP_RESETACK:
2251                 /* reset the [de]compressor */
2252                 if ((ppp->flags & SC_CCP_UP) == 0)
2253                         break;
2254                 if (inbound) {
2255                         if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
2256                                 ppp->rcomp->decomp_reset(ppp->rc_state);
2257                                 ppp->rstate &= ~SC_DC_ERROR;
2258                         }
2259                 } else {
2260                         if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
2261                                 ppp->xcomp->comp_reset(ppp->xc_state);
2262                 }
2263                 break;
2264         }
2265 }
2266
2267 /* Free up compression resources. */
2268 static void
2269 ppp_ccp_closed(struct ppp *ppp)
2270 {
2271         void *xstate, *rstate;
2272         struct compressor *xcomp, *rcomp;
2273
2274         ppp_lock(ppp);
2275         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
2276         ppp->xstate = 0;
2277         xcomp = ppp->xcomp;
2278         xstate = ppp->xc_state;
2279         ppp->xc_state = NULL;
2280         ppp->rstate = 0;
2281         rcomp = ppp->rcomp;
2282         rstate = ppp->rc_state;
2283         ppp->rc_state = NULL;
2284         ppp_unlock(ppp);
2285
2286         if (xstate) {
2287                 xcomp->comp_free(xstate);
2288                 module_put(xcomp->owner);
2289         }
2290         if (rstate) {
2291                 rcomp->decomp_free(rstate);
2292                 module_put(rcomp->owner);
2293         }
2294 }
2295
2296 /* List of compressors. */
2297 static LIST_HEAD(compressor_list);
2298 static DEFINE_SPINLOCK(compressor_list_lock);
2299
2300 struct compressor_entry {
2301         struct list_head list;
2302         struct compressor *comp;
2303 };
2304
2305 static struct compressor_entry *
2306 find_comp_entry(int proto)
2307 {
2308         struct compressor_entry *ce;
2309
2310         list_for_each_entry(ce, &compressor_list, list) {
2311                 if (ce->comp->compress_proto == proto)
2312                         return ce;
2313         }
2314         return NULL;
2315 }
2316
2317 /* Register a compressor */
2318 int
2319 ppp_register_compressor(struct compressor *cp)
2320 {
2321         struct compressor_entry *ce;
2322         int ret;
2323         spin_lock(&compressor_list_lock);
2324         ret = -EEXIST;
2325         if (find_comp_entry(cp->compress_proto))
2326                 goto out;
2327         ret = -ENOMEM;
2328         ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
2329         if (!ce)
2330                 goto out;
2331         ret = 0;
2332         ce->comp = cp;
2333         list_add(&ce->list, &compressor_list);
2334  out:
2335         spin_unlock(&compressor_list_lock);
2336         return ret;
2337 }
2338
2339 /* Unregister a compressor */
2340 void
2341 ppp_unregister_compressor(struct compressor *cp)
2342 {
2343         struct compressor_entry *ce;
2344
2345         spin_lock(&compressor_list_lock);
2346         ce = find_comp_entry(cp->compress_proto);
2347         if (ce && ce->comp == cp) {
2348                 list_del(&ce->list);
2349                 kfree(ce);
2350         }
2351         spin_unlock(&compressor_list_lock);
2352 }
2353
2354 /* Find a compressor. */
2355 static struct compressor *
2356 find_compressor(int type)
2357 {
2358         struct compressor_entry *ce;
2359         struct compressor *cp = NULL;
2360
2361         spin_lock(&compressor_list_lock);
2362         ce = find_comp_entry(type);
2363         if (ce) {
2364                 cp = ce->comp;
2365                 if (!try_module_get(cp->owner))
2366                         cp = NULL;
2367         }
2368         spin_unlock(&compressor_list_lock);
2369         return cp;
2370 }
2371
2372 /*
2373  * Miscelleneous stuff.
2374  */
2375
2376 static void
2377 ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
2378 {
2379         struct slcompress *vj = ppp->vj;
2380
2381         memset(st, 0, sizeof(*st));
2382         st->p.ppp_ipackets = ppp->dev->stats.rx_packets;
2383         st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
2384         st->p.ppp_ibytes = ppp->dev->stats.rx_bytes;
2385         st->p.ppp_opackets = ppp->dev->stats.tx_packets;
2386         st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
2387         st->p.ppp_obytes = ppp->dev->stats.tx_bytes;
2388         if (!vj)
2389                 return;
2390         st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
2391         st->vj.vjs_compressed = vj->sls_o_compressed;
2392         st->vj.vjs_searches = vj->sls_o_searches;
2393         st->vj.vjs_misses = vj->sls_o_misses;
2394         st->vj.vjs_errorin = vj->sls_i_error;
2395         st->vj.vjs_tossed = vj->sls_i_tossed;
2396         st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
2397         st->vj.vjs_compressedin = vj->sls_i_compressed;
2398 }
2399
2400 /*
2401  * Stuff for handling the lists of ppp units and channels
2402  * and for initialization.
2403  */
2404
2405 /*
2406  * Create a new ppp interface unit.  Fails if it can't allocate memory
2407  * or if there is already a unit with the requested number.
2408  * unit == -1 means allocate a new number.
2409  */
2410 static struct ppp *
2411 ppp_create_interface(int unit, int *retp)
2412 {
2413         struct ppp *ppp;
2414         struct net_device *dev = NULL;
2415         int ret = -ENOMEM;
2416         int i;
2417
2418         ppp = kzalloc(sizeof(struct ppp), GFP_KERNEL);
2419         if (!ppp)
2420                 goto out;
2421         dev = alloc_netdev(0, "", ppp_setup);
2422         if (!dev)
2423                 goto out1;
2424
2425         ppp->mru = PPP_MRU;
2426         init_ppp_file(&ppp->file, INTERFACE);
2427         ppp->file.hdrlen = PPP_HDRLEN - 2;      /* don't count proto bytes */
2428         for (i = 0; i < NUM_NP; ++i)
2429                 ppp->npmode[i] = NPMODE_PASS;
2430         INIT_LIST_HEAD(&ppp->channels);
2431         spin_lock_init(&ppp->rlock);
2432         spin_lock_init(&ppp->wlock);
2433 #ifdef CONFIG_PPP_MULTILINK
2434         ppp->minseq = -1;
2435         skb_queue_head_init(&ppp->mrq);
2436 #endif /* CONFIG_PPP_MULTILINK */
2437         ppp->dev = dev;
2438         dev->priv = ppp;
2439
2440         dev->hard_start_xmit = ppp_start_xmit;
2441         dev->do_ioctl = ppp_net_ioctl;
2442
2443         ret = -EEXIST;
2444         mutex_lock(&all_ppp_mutex);
2445         if (unit < 0)
2446                 unit = cardmap_find_first_free(all_ppp_units);
2447         else if (cardmap_get(all_ppp_units, unit) != NULL)
2448                 goto out2;      /* unit already exists */
2449
2450         /* Initialize the new ppp unit */
2451         ppp->file.index = unit;
2452         sprintf(dev->name, "ppp%d", unit);
2453
2454         ret = register_netdev(dev);
2455         if (ret != 0) {
2456                 printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
2457                        dev->name, ret);
2458                 goto out2;
2459         }
2460
2461         atomic_inc(&ppp_unit_count);
2462         ret = cardmap_set(&all_ppp_units, unit, ppp);
2463         if (ret != 0)
2464                 goto out3;
2465
2466         mutex_unlock(&all_ppp_mutex);
2467         *retp = 0;
2468         return ppp;
2469
2470 out3:
2471         atomic_dec(&ppp_unit_count);
2472         unregister_netdev(dev);
2473 out2:
2474         mutex_unlock(&all_ppp_mutex);
2475         free_netdev(dev);
2476 out1:
2477         kfree(ppp);
2478 out:
2479         *retp = ret;
2480         return NULL;
2481 }
2482
2483 /*
2484  * Initialize a ppp_file structure.
2485  */
2486 static void
2487 init_ppp_file(struct ppp_file *pf, int kind)
2488 {
2489         pf->kind = kind;
2490         skb_queue_head_init(&pf->xq);
2491         skb_queue_head_init(&pf->rq);
2492         atomic_set(&pf->refcnt, 1);
2493         init_waitqueue_head(&pf->rwait);
2494 }
2495
2496 /*
2497  * Take down a ppp interface unit - called when the owning file
2498  * (the one that created the unit) is closed or detached.
2499  */
2500 static void ppp_shutdown_interface(struct ppp *ppp)
2501 {
2502         struct net_device *dev;
2503
2504         mutex_lock(&all_ppp_mutex);
2505         ppp_lock(ppp);
2506         dev = ppp->dev;
2507         ppp->dev = NULL;
2508         ppp_unlock(ppp);
2509         /* This will call dev_close() for us. */
2510         if (dev) {
2511                 unregister_netdev(dev);
2512                 free_netdev(dev);
2513         }
2514         cardmap_set(&all_ppp_units, ppp->file.index, NULL);
2515         ppp->file.dead = 1;
2516         ppp->owner = NULL;
2517         wake_up_interruptible(&ppp->file.rwait);
2518         mutex_unlock(&all_ppp_mutex);
2519 }
2520
2521 /*
2522  * Free the memory used by a ppp unit.  This is only called once
2523  * there are no channels connected to the unit and no file structs
2524  * that reference the unit.
2525  */
2526 static void ppp_destroy_interface(struct ppp *ppp)
2527 {
2528         atomic_dec(&ppp_unit_count);
2529
2530         if (!ppp->file.dead || ppp->n_channels) {
2531                 /* "can't happen" */
2532                 printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
2533                        "n_channels=%d !\n", ppp, ppp->file.dead,
2534                        ppp->n_channels);
2535                 return;
2536         }
2537
2538         ppp_ccp_closed(ppp);
2539         if (ppp->vj) {
2540                 slhc_free(ppp->vj);
2541                 ppp->vj = NULL;
2542         }
2543         skb_queue_purge(&ppp->file.xq);
2544         skb_queue_purge(&ppp->file.rq);
2545 #ifdef CONFIG_PPP_MULTILINK
2546         skb_queue_purge(&ppp->mrq);
2547 #endif /* CONFIG_PPP_MULTILINK */
2548 #ifdef CONFIG_PPP_FILTER
2549         kfree(ppp->pass_filter);
2550         ppp->pass_filter = NULL;
2551         kfree(ppp->active_filter);
2552         ppp->active_filter = NULL;
2553 #endif /* CONFIG_PPP_FILTER */
2554
2555         if (ppp->xmit_pending)
2556                 kfree_skb(ppp->xmit_pending);
2557
2558         kfree(ppp);
2559 }
2560
2561 /*
2562  * Locate an existing ppp unit.
2563  * The caller should have locked the all_ppp_mutex.
2564  */
2565 static struct ppp *
2566 ppp_find_unit(int unit)
2567 {
2568         return cardmap_get(all_ppp_units, unit);
2569 }
2570
2571 /*
2572  * Locate an existing ppp channel.
2573  * The caller should have locked the all_channels_lock.
2574  * First we look in the new_channels list, then in the
2575  * all_channels list.  If found in the new_channels list,
2576  * we move it to the all_channels list.  This is for speed
2577  * when we have a lot of channels in use.
2578  */
2579 static struct channel *
2580 ppp_find_channel(int unit)
2581 {
2582         struct channel *pch;
2583
2584         list_for_each_entry(pch, &new_channels, list) {
2585                 if (pch->file.index == unit) {
2586                         list_move(&pch->list, &all_channels);
2587                         return pch;
2588                 }
2589         }
2590         list_for_each_entry(pch, &all_channels, list) {
2591                 if (pch->file.index == unit)
2592                         return pch;
2593         }
2594         return NULL;
2595 }
2596
2597 /*
2598  * Connect a PPP channel to a PPP interface unit.
2599  */
2600 static int
2601 ppp_connect_channel(struct channel *pch, int unit)
2602 {
2603         struct ppp *ppp;
2604         int ret = -ENXIO;
2605         int hdrlen;
2606
2607         mutex_lock(&all_ppp_mutex);
2608         ppp = ppp_find_unit(unit);
2609         if (!ppp)
2610                 goto out;
2611         write_lock_bh(&pch->upl);
2612         ret = -EINVAL;
2613         if (pch->ppp)
2614                 goto outl;
2615
2616         ppp_lock(ppp);
2617         if (pch->file.hdrlen > ppp->file.hdrlen)
2618                 ppp->file.hdrlen = pch->file.hdrlen;
2619         hdrlen = pch->file.hdrlen + 2;  /* for protocol bytes */
2620         if (ppp->dev && hdrlen > ppp->dev->hard_header_len)
2621                 ppp->dev->hard_header_len = hdrlen;
2622         list_add_tail(&pch->clist, &ppp->channels);
2623         ++ppp->n_channels;
2624         pch->ppp = ppp;
2625         atomic_inc(&ppp->file.refcnt);
2626         ppp_unlock(ppp);
2627         ret = 0;
2628
2629  outl:
2630         write_unlock_bh(&pch->upl);
2631  out:
2632         mutex_unlock(&all_ppp_mutex);
2633         return ret;
2634 }
2635
2636 /*
2637  * Disconnect a channel from its ppp unit.
2638  */
2639 static int
2640 ppp_disconnect_channel(struct channel *pch)
2641 {
2642         struct ppp *ppp;
2643         int err = -EINVAL;
2644
2645         write_lock_bh(&pch->upl);
2646         ppp = pch->ppp;
2647         pch->ppp = NULL;
2648         write_unlock_bh(&pch->upl);
2649         if (ppp) {
2650                 /* remove it from the ppp unit's list */
2651                 ppp_lock(ppp);
2652                 list_del(&pch->clist);
2653                 if (--ppp->n_channels == 0)
2654                         wake_up_interruptible(&ppp->file.rwait);
2655                 ppp_unlock(ppp);
2656                 if (atomic_dec_and_test(&ppp->file.refcnt))
2657                         ppp_destroy_interface(ppp);
2658                 err = 0;
2659         }
2660         return err;
2661 }
2662
2663 /*
2664  * Free up the resources used by a ppp channel.
2665  */
2666 static void ppp_destroy_channel(struct channel *pch)
2667 {
2668         atomic_dec(&channel_count);
2669
2670         if (!pch->file.dead) {
2671                 /* "can't happen" */
2672                 printk(KERN_ERR "ppp: destroying undead channel %p !\n",
2673                        pch);
2674                 return;
2675         }
2676         skb_queue_purge(&pch->file.xq);
2677         skb_queue_purge(&pch->file.rq);
2678         kfree(pch);
2679 }
2680
2681 static void __exit ppp_cleanup(void)
2682 {
2683         /* should never happen */
2684         if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
2685                 printk(KERN_ERR "PPP: removing module but units remain!\n");
2686         cardmap_destroy(&all_ppp_units);
2687         unregister_chrdev(PPP_MAJOR, "ppp");
2688         device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
2689         class_destroy(ppp_class);
2690 }
2691
2692 /*
2693  * Cardmap implementation.
2694  */
2695 static void *cardmap_get(struct cardmap *map, unsigned int nr)
2696 {
2697         struct cardmap *p;
2698         int i;
2699
2700         for (p = map; p != NULL; ) {
2701                 if ((i = nr >> p->shift) >= CARDMAP_WIDTH)
2702                         return NULL;
2703                 if (p->shift == 0)
2704                         return p->ptr[i];
2705                 nr &= ~(CARDMAP_MASK << p->shift);
2706                 p = p->ptr[i];
2707         }
2708         return NULL;
2709 }
2710
2711 static int cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
2712 {
2713         struct cardmap *p;
2714         int i;
2715
2716         p = *pmap;
2717         if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
2718                 do {
2719                         /* need a new top level */
2720                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2721                         if (!np)
2722                                 goto enomem;
2723                         np->ptr[0] = p;
2724                         if (p != NULL) {
2725                                 np->shift = p->shift + CARDMAP_ORDER;
2726                                 p->parent = np;
2727                         } else
2728                                 np->shift = 0;
2729                         p = np;
2730                 } while ((nr >> p->shift) >= CARDMAP_WIDTH);
2731                 *pmap = p;
2732         }
2733         while (p->shift > 0) {
2734                 i = (nr >> p->shift) & CARDMAP_MASK;
2735                 if (p->ptr[i] == NULL) {
2736                         struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
2737                         if (!np)
2738                                 goto enomem;
2739                         np->shift = p->shift - CARDMAP_ORDER;
2740                         np->parent = p;
2741                         p->ptr[i] = np;
2742                 }
2743                 if (ptr == NULL)
2744                         clear_bit(i, &p->inuse);
2745                 p = p->ptr[i];
2746         }
2747         i = nr & CARDMAP_MASK;
2748         p->ptr[i] = ptr;
2749         if (ptr != NULL)
2750                 set_bit(i, &p->inuse);
2751         else
2752                 clear_bit(i, &p->inuse);
2753         return 0;
2754  enomem:
2755         return -ENOMEM;
2756 }
2757
2758 static unsigned int cardmap_find_first_free(struct cardmap *map)
2759 {
2760         struct cardmap *p;
2761         unsigned int nr = 0;
2762         int i;
2763
2764         if ((p = map) == NULL)
2765                 return 0;
2766         for (;;) {
2767                 i = find_first_zero_bit(&p->inuse, CARDMAP_WIDTH);
2768                 if (i >= CARDMAP_WIDTH) {
2769                         if (p->parent == NULL)
2770                                 return CARDMAP_WIDTH << p->shift;
2771                         p = p->parent;
2772                         i = (nr >> p->shift) & CARDMAP_MASK;
2773                         set_bit(i, &p->inuse);
2774                         continue;
2775                 }
2776                 nr = (nr & (~CARDMAP_MASK << p->shift)) | (i << p->shift);
2777                 if (p->shift == 0 || p->ptr[i] == NULL)
2778                         return nr;
2779                 p = p->ptr[i];
2780         }
2781 }
2782
2783 static void cardmap_destroy(struct cardmap **pmap)
2784 {
2785         struct cardmap *p, *np;
2786         int i;
2787
2788         for (p = *pmap; p != NULL; p = np) {
2789                 if (p->shift != 0) {
2790                         for (i = 0; i < CARDMAP_WIDTH; ++i)
2791                                 if (p->ptr[i] != NULL)
2792                                         break;
2793                         if (i < CARDMAP_WIDTH) {
2794                                 np = p->ptr[i];
2795                                 p->ptr[i] = NULL;
2796                                 continue;
2797                         }
2798                 }
2799                 np = p->parent;
2800                 kfree(p);
2801         }
2802         *pmap = NULL;
2803 }
2804
2805 /* Module/initialization stuff */
2806
2807 module_init(ppp_init);
2808 module_exit(ppp_cleanup);
2809
2810 EXPORT_SYMBOL(ppp_register_channel);
2811 EXPORT_SYMBOL(ppp_unregister_channel);
2812 EXPORT_SYMBOL(ppp_channel_index);
2813 EXPORT_SYMBOL(ppp_unit_number);
2814 EXPORT_SYMBOL(ppp_input);
2815 EXPORT_SYMBOL(ppp_input_error);
2816 EXPORT_SYMBOL(ppp_output_wakeup);
2817 EXPORT_SYMBOL(ppp_register_compressor);
2818 EXPORT_SYMBOL(ppp_unregister_compressor);
2819 MODULE_LICENSE("GPL");
2820 MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
2821 MODULE_ALIAS("/dev/ppp");