Commit | Line | Data |
---|---|---|
2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1da177e4 LT |
2 | /* |
3 | * PPP synchronous tty channel driver for Linux. | |
4 | * | |
5 | * This is a ppp channel driver that can be used with tty device drivers | |
6 | * that are frame oriented, such as synchronous HDLC devices. | |
7 | * | |
8 | * Complete PPP frames without encoding/decoding are exchanged between | |
9 | * the channel driver and the device driver. | |
6aa20a22 | 10 | * |
1da177e4 LT |
11 | * The async map IOCTL codes are implemented to keep the user mode |
12 | * applications happy if they call them. Synchronous PPP does not use | |
13 | * the async maps. | |
14 | * | |
15 | * Copyright 1999 Paul Mackerras. | |
16 | * | |
17 | * Also touched by the grubby hands of Paul Fulghum paulkf@microgate.com | |
18 | * | |
1da177e4 LT |
19 | * This driver provides the encapsulation and framing for sending |
20 | * and receiving PPP frames over sync serial lines. It relies on | |
21 | * the generic PPP layer to give it frames to send and to process | |
22 | * received frames. It implements the PPP line discipline. | |
23 | * | |
24 | * Part of the code in this driver was inspired by the old async-only | |
25 | * PPP driver, written by Michael Callahan and Al Longyear, and | |
26 | * subsequently hacked by Paul Mackerras. | |
27 | * | |
28 | * ==FILEVERSION 20040616== | |
29 | */ | |
30 | ||
31 | #include <linux/module.h> | |
32 | #include <linux/kernel.h> | |
33 | #include <linux/skbuff.h> | |
34 | #include <linux/tty.h> | |
35 | #include <linux/netdevice.h> | |
36 | #include <linux/poll.h> | |
37 | #include <linux/ppp_defs.h> | |
4b32da2b | 38 | #include <linux/ppp-ioctl.h> |
1da177e4 LT |
39 | #include <linux/ppp_channel.h> |
40 | #include <linux/spinlock.h> | |
5e41fb83 | 41 | #include <linux/completion.h> |
1da177e4 | 42 | #include <linux/init.h> |
a6b7a407 | 43 | #include <linux/interrupt.h> |
5a0e3ad6 | 44 | #include <linux/slab.h> |
709c89b4 | 45 | #include <linux/refcount.h> |
96545aeb | 46 | #include <asm/unaligned.h> |
7c0f6ba6 | 47 | #include <linux/uaccess.h> |
1da177e4 LT |
48 | |
49 | #define PPP_VERSION "2.4.2" | |
50 | ||
51 | /* Structure for storing local state. */ | |
52 | struct syncppp { | |
53 | struct tty_struct *tty; | |
54 | unsigned int flags; | |
55 | unsigned int rbits; | |
56 | int mru; | |
57 | spinlock_t xmit_lock; | |
58 | spinlock_t recv_lock; | |
59 | unsigned long xmit_flags; | |
60 | u32 xaccm[8]; | |
61 | u32 raccm; | |
62 | unsigned int bytes_sent; | |
63 | unsigned int bytes_rcvd; | |
64 | ||
65 | struct sk_buff *tpkt; | |
66 | unsigned long last_xmit; | |
67 | ||
68 | struct sk_buff_head rqueue; | |
69 | ||
70 | struct tasklet_struct tsk; | |
71 | ||
709c89b4 | 72 | refcount_t refcnt; |
5e41fb83 | 73 | struct completion dead_cmp; |
1da177e4 LT |
74 | struct ppp_channel chan; /* interface to generic ppp layer */ |
75 | }; | |
76 | ||
77 | /* Bit numbers in xmit_flags */ | |
78 | #define XMIT_WAKEUP 0 | |
79 | #define XMIT_FULL 1 | |
80 | ||
81 | /* Bits in rbits */ | |
82 | #define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP) | |
83 | ||
84 | #define PPPSYNC_MAX_RQLEN 32 /* arbitrary */ | |
85 | ||
86 | /* | |
87 | * Prototypes. | |
88 | */ | |
89 | static struct sk_buff* ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *); | |
90 | static int ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb); | |
91 | static int ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd, | |
92 | unsigned long arg); | |
64ca5aba | 93 | static void ppp_sync_process(struct tasklet_struct *t); |
1da177e4 LT |
94 | static int ppp_sync_push(struct syncppp *ap); |
95 | static void ppp_sync_flush_output(struct syncppp *ap); | |
892bc209 | 96 | static void ppp_sync_input(struct syncppp *ap, const u8 *buf, const u8 *flags, |
a8d9cd23 | 97 | int count); |
1da177e4 | 98 | |
d7100da0 | 99 | static const struct ppp_channel_ops sync_ops = { |
100 | .start_xmit = ppp_sync_send, | |
101 | .ioctl = ppp_sync_ioctl, | |
1da177e4 LT |
102 | }; |
103 | ||
104 | /* | |
167bfa71 | 105 | * Utility procedure to print a buffer in hex/ascii |
1da177e4 | 106 | */ |
1da177e4 LT |
107 | static void |
108 | ppp_print_buffer (const char *name, const __u8 *buf, int count) | |
109 | { | |
1da177e4 LT |
110 | if (name != NULL) |
111 | printk(KERN_DEBUG "ppp_synctty: %s, count = %d\n", name, count); | |
112 | ||
167bfa71 | 113 | print_hex_dump_bytes("", DUMP_PREFIX_NONE, buf, count); |
1da177e4 LT |
114 | } |
115 | ||
116 | ||
117 | /* | |
118 | * Routines implementing the synchronous PPP line discipline. | |
119 | */ | |
120 | ||
121 | /* | |
122 | * We have a potential race on dereferencing tty->disc_data, | |
123 | * because the tty layer provides no locking at all - thus one | |
124 | * cpu could be running ppp_synctty_receive while another | |
125 | * calls ppp_synctty_close, which zeroes tty->disc_data and | |
126 | * frees the memory that ppp_synctty_receive is using. The best | |
127 | * way to fix this is to use a rwlock in the tty struct, but for now | |
128 | * we use a single global rwlock for all ttys in ppp line discipline. | |
129 | * | |
25985edc | 130 | * FIXME: Fixed in tty_io nowadays. |
1da177e4 LT |
131 | */ |
132 | static DEFINE_RWLOCK(disc_data_lock); | |
133 | ||
134 | static struct syncppp *sp_get(struct tty_struct *tty) | |
135 | { | |
136 | struct syncppp *ap; | |
137 | ||
138 | read_lock(&disc_data_lock); | |
139 | ap = tty->disc_data; | |
140 | if (ap != NULL) | |
709c89b4 | 141 | refcount_inc(&ap->refcnt); |
1da177e4 LT |
142 | read_unlock(&disc_data_lock); |
143 | return ap; | |
144 | } | |
145 | ||
146 | static void sp_put(struct syncppp *ap) | |
147 | { | |
709c89b4 | 148 | if (refcount_dec_and_test(&ap->refcnt)) |
5e41fb83 | 149 | complete(&ap->dead_cmp); |
1da177e4 LT |
150 | } |
151 | ||
152 | /* | |
153 | * Called when a tty is put into sync-PPP line discipline. | |
154 | */ | |
155 | static int | |
156 | ppp_sync_open(struct tty_struct *tty) | |
157 | { | |
158 | struct syncppp *ap; | |
159 | int err; | |
9c705260 | 160 | int speed; |
1da177e4 | 161 | |
f34d7a5b AC |
162 | if (tty->ops->write == NULL) |
163 | return -EOPNOTSUPP; | |
164 | ||
dd00cc48 | 165 | ap = kzalloc(sizeof(*ap), GFP_KERNEL); |
1da177e4 | 166 | err = -ENOMEM; |
cd228d54 | 167 | if (!ap) |
1da177e4 LT |
168 | goto out; |
169 | ||
170 | /* initialize the syncppp structure */ | |
1da177e4 LT |
171 | ap->tty = tty; |
172 | ap->mru = PPP_MRU; | |
173 | spin_lock_init(&ap->xmit_lock); | |
174 | spin_lock_init(&ap->recv_lock); | |
175 | ap->xaccm[0] = ~0U; | |
176 | ap->xaccm[3] = 0x60000000U; | |
177 | ap->raccm = ~0U; | |
178 | ||
179 | skb_queue_head_init(&ap->rqueue); | |
64ca5aba | 180 | tasklet_setup(&ap->tsk, ppp_sync_process); |
1da177e4 | 181 | |
709c89b4 | 182 | refcount_set(&ap->refcnt, 1); |
5e41fb83 | 183 | init_completion(&ap->dead_cmp); |
1da177e4 LT |
184 | |
185 | ap->chan.private = ap; | |
186 | ap->chan.ops = &sync_ops; | |
187 | ap->chan.mtu = PPP_MRU; | |
188 | ap->chan.hdrlen = 2; /* for A/C bytes */ | |
9c705260 GP |
189 | speed = tty_get_baud_rate(tty); |
190 | ap->chan.speed = speed; | |
1da177e4 LT |
191 | err = ppp_register_channel(&ap->chan); |
192 | if (err) | |
193 | goto out_free; | |
194 | ||
195 | tty->disc_data = ap; | |
33f0f88f | 196 | tty->receive_room = 65536; |
1da177e4 LT |
197 | return 0; |
198 | ||
199 | out_free: | |
200 | kfree(ap); | |
201 | out: | |
202 | return err; | |
203 | } | |
204 | ||
205 | /* | |
206 | * Called when the tty is put into another line discipline | |
207 | * or it hangs up. We have to wait for any cpu currently | |
208 | * executing in any of the other ppp_synctty_* routines to | |
209 | * finish before we can call ppp_unregister_channel and free | |
210 | * the syncppp struct. This routine must be called from | |
211 | * process context, not interrupt or softirq context. | |
212 | */ | |
213 | static void | |
214 | ppp_sync_close(struct tty_struct *tty) | |
215 | { | |
216 | struct syncppp *ap; | |
217 | ||
218 | write_lock_irq(&disc_data_lock); | |
219 | ap = tty->disc_data; | |
220 | tty->disc_data = NULL; | |
221 | write_unlock_irq(&disc_data_lock); | |
cd228d54 | 222 | if (!ap) |
1da177e4 LT |
223 | return; |
224 | ||
225 | /* | |
226 | * We have now ensured that nobody can start using ap from now | |
227 | * on, but we have to wait for all existing users to finish. | |
228 | * Note that ppp_unregister_channel ensures that no calls to | |
229 | * our channel ops (i.e. ppp_sync_send/ioctl) are in progress | |
230 | * by the time it returns. | |
231 | */ | |
709c89b4 | 232 | if (!refcount_dec_and_test(&ap->refcnt)) |
5e41fb83 | 233 | wait_for_completion(&ap->dead_cmp); |
1da177e4 LT |
234 | tasklet_kill(&ap->tsk); |
235 | ||
236 | ppp_unregister_channel(&ap->chan); | |
237 | skb_queue_purge(&ap->rqueue); | |
1d2f8c95 | 238 | kfree_skb(ap->tpkt); |
1da177e4 LT |
239 | kfree(ap); |
240 | } | |
241 | ||
242 | /* | |
243 | * Called on tty hangup in process context. | |
244 | * | |
245 | * Wait for I/O to driver to complete and unregister PPP channel. | |
246 | * This is already done by the close routine, so just call that. | |
247 | */ | |
28f194da | 248 | static void ppp_sync_hangup(struct tty_struct *tty) |
1da177e4 LT |
249 | { |
250 | ppp_sync_close(tty); | |
1da177e4 LT |
251 | } |
252 | ||
253 | /* | |
254 | * Read does nothing - no data is ever available this way. | |
255 | * Pppd reads and writes packets via /dev/ppp instead. | |
256 | */ | |
257 | static ssize_t | |
49b8220c | 258 | ppp_sync_read(struct tty_struct *tty, struct file *file, u8 *buf, size_t count, |
3b830a9c | 259 | void **cookie, unsigned long offset) |
1da177e4 LT |
260 | { |
261 | return -EAGAIN; | |
262 | } | |
263 | ||
264 | /* | |
265 | * Write on the tty does nothing, the packets all come in | |
266 | * from the ppp generic stuff. | |
267 | */ | |
268 | static ssize_t | |
49b8220c JSS |
269 | ppp_sync_write(struct tty_struct *tty, struct file *file, const u8 *buf, |
270 | size_t count) | |
1da177e4 LT |
271 | { |
272 | return -EAGAIN; | |
273 | } | |
274 | ||
275 | static int | |
d78328bc | 276 | ppp_synctty_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg) |
1da177e4 LT |
277 | { |
278 | struct syncppp *ap = sp_get(tty); | |
279 | int __user *p = (int __user *)arg; | |
280 | int err, val; | |
281 | ||
cd228d54 | 282 | if (!ap) |
1da177e4 LT |
283 | return -ENXIO; |
284 | err = -EFAULT; | |
285 | switch (cmd) { | |
286 | case PPPIOCGCHAN: | |
1da177e4 LT |
287 | err = -EFAULT; |
288 | if (put_user(ppp_channel_index(&ap->chan), p)) | |
289 | break; | |
290 | err = 0; | |
291 | break; | |
292 | ||
293 | case PPPIOCGUNIT: | |
1da177e4 LT |
294 | err = -EFAULT; |
295 | if (put_user(ppp_unit_number(&ap->chan), p)) | |
296 | break; | |
297 | err = 0; | |
298 | break; | |
299 | ||
1da177e4 LT |
300 | case TCFLSH: |
301 | /* flush our buffers and the serial port's buffer */ | |
302 | if (arg == TCIOFLUSH || arg == TCOFLUSH) | |
303 | ppp_sync_flush_output(ap); | |
7c783601 | 304 | err = n_tty_ioctl_helper(tty, cmd, arg); |
1da177e4 LT |
305 | break; |
306 | ||
307 | case FIONREAD: | |
308 | val = 0; | |
309 | if (put_user(val, p)) | |
310 | break; | |
311 | err = 0; | |
312 | break; | |
313 | ||
314 | default: | |
dcc223e8 | 315 | err = tty_mode_ioctl(tty, cmd, arg); |
d0127539 | 316 | break; |
1da177e4 LT |
317 | } |
318 | ||
319 | sp_put(ap); | |
320 | return err; | |
321 | } | |
322 | ||
92d326f6 | 323 | /* May sleep, don't call from interrupt level or with interrupts disabled */ |
55db4c64 | 324 | static void |
892bc209 | 325 | ppp_sync_receive(struct tty_struct *tty, const u8 *buf, const u8 *cflags, |
a8d9cd23 | 326 | size_t count) |
1da177e4 LT |
327 | { |
328 | struct syncppp *ap = sp_get(tty); | |
329 | unsigned long flags; | |
330 | ||
cd228d54 | 331 | if (!ap) |
55db4c64 | 332 | return; |
1da177e4 LT |
333 | spin_lock_irqsave(&ap->recv_lock, flags); |
334 | ppp_sync_input(ap, buf, cflags, count); | |
335 | spin_unlock_irqrestore(&ap->recv_lock, flags); | |
b03efcfb | 336 | if (!skb_queue_empty(&ap->rqueue)) |
1da177e4 LT |
337 | tasklet_schedule(&ap->tsk); |
338 | sp_put(ap); | |
4a21b8cb | 339 | tty_unthrottle(tty); |
1da177e4 LT |
340 | } |
341 | ||
342 | static void | |
343 | ppp_sync_wakeup(struct tty_struct *tty) | |
344 | { | |
345 | struct syncppp *ap = sp_get(tty); | |
346 | ||
347 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); | |
cd228d54 | 348 | if (!ap) |
1da177e4 LT |
349 | return; |
350 | set_bit(XMIT_WAKEUP, &ap->xmit_flags); | |
351 | tasklet_schedule(&ap->tsk); | |
352 | sp_put(ap); | |
353 | } | |
354 | ||
355 | ||
a352def2 | 356 | static struct tty_ldisc_ops ppp_sync_ldisc = { |
1da177e4 | 357 | .owner = THIS_MODULE, |
fbadf70a | 358 | .num = N_SYNC_PPP, |
1da177e4 LT |
359 | .name = "pppsync", |
360 | .open = ppp_sync_open, | |
361 | .close = ppp_sync_close, | |
362 | .hangup = ppp_sync_hangup, | |
363 | .read = ppp_sync_read, | |
364 | .write = ppp_sync_write, | |
365 | .ioctl = ppp_synctty_ioctl, | |
1da177e4 LT |
366 | .receive_buf = ppp_sync_receive, |
367 | .write_wakeup = ppp_sync_wakeup, | |
368 | }; | |
369 | ||
370 | static int __init | |
371 | ppp_sync_init(void) | |
372 | { | |
373 | int err; | |
374 | ||
fbadf70a | 375 | err = tty_register_ldisc(&ppp_sync_ldisc); |
1da177e4 LT |
376 | if (err != 0) |
377 | printk(KERN_ERR "PPP_sync: error %d registering line disc.\n", | |
378 | err); | |
379 | return err; | |
380 | } | |
381 | ||
382 | /* | |
383 | * The following routines provide the PPP channel interface. | |
384 | */ | |
385 | static int | |
386 | ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg) | |
387 | { | |
388 | struct syncppp *ap = chan->private; | |
389 | int err, val; | |
390 | u32 accm[8]; | |
391 | void __user *argp = (void __user *)arg; | |
392 | u32 __user *p = argp; | |
393 | ||
394 | err = -EFAULT; | |
395 | switch (cmd) { | |
396 | case PPPIOCGFLAGS: | |
397 | val = ap->flags | ap->rbits; | |
398 | if (put_user(val, (int __user *) argp)) | |
399 | break; | |
400 | err = 0; | |
401 | break; | |
402 | case PPPIOCSFLAGS: | |
403 | if (get_user(val, (int __user *) argp)) | |
404 | break; | |
405 | ap->flags = val & ~SC_RCV_BITS; | |
406 | spin_lock_irq(&ap->recv_lock); | |
407 | ap->rbits = val & SC_RCV_BITS; | |
408 | spin_unlock_irq(&ap->recv_lock); | |
409 | err = 0; | |
410 | break; | |
411 | ||
412 | case PPPIOCGASYNCMAP: | |
413 | if (put_user(ap->xaccm[0], p)) | |
414 | break; | |
415 | err = 0; | |
416 | break; | |
417 | case PPPIOCSASYNCMAP: | |
418 | if (get_user(ap->xaccm[0], p)) | |
419 | break; | |
420 | err = 0; | |
421 | break; | |
422 | ||
423 | case PPPIOCGRASYNCMAP: | |
424 | if (put_user(ap->raccm, p)) | |
425 | break; | |
426 | err = 0; | |
427 | break; | |
428 | case PPPIOCSRASYNCMAP: | |
429 | if (get_user(ap->raccm, p)) | |
430 | break; | |
431 | err = 0; | |
432 | break; | |
433 | ||
434 | case PPPIOCGXASYNCMAP: | |
435 | if (copy_to_user(argp, ap->xaccm, sizeof(ap->xaccm))) | |
436 | break; | |
437 | err = 0; | |
438 | break; | |
439 | case PPPIOCSXASYNCMAP: | |
440 | if (copy_from_user(accm, argp, sizeof(accm))) | |
441 | break; | |
442 | accm[2] &= ~0x40000000U; /* can't escape 0x5e */ | |
443 | accm[3] |= 0x60000000U; /* must escape 0x7d, 0x7e */ | |
444 | memcpy(ap->xaccm, accm, sizeof(ap->xaccm)); | |
445 | err = 0; | |
446 | break; | |
447 | ||
448 | case PPPIOCGMRU: | |
449 | if (put_user(ap->mru, (int __user *) argp)) | |
450 | break; | |
451 | err = 0; | |
452 | break; | |
453 | case PPPIOCSMRU: | |
454 | if (get_user(val, (int __user *) argp)) | |
455 | break; | |
c0a2a1b0 WB |
456 | if (val > U16_MAX) { |
457 | err = -EINVAL; | |
458 | break; | |
459 | } | |
1da177e4 LT |
460 | if (val < PPP_MRU) |
461 | val = PPP_MRU; | |
462 | ap->mru = val; | |
463 | err = 0; | |
464 | break; | |
465 | ||
466 | default: | |
467 | err = -ENOTTY; | |
468 | } | |
469 | return err; | |
470 | } | |
471 | ||
472 | /* | |
473 | * This is called at softirq level to deliver received packets | |
474 | * to the ppp_generic code, and to tell the ppp_generic code | |
475 | * if we can accept more output now. | |
476 | */ | |
64ca5aba | 477 | static void ppp_sync_process(struct tasklet_struct *t) |
1da177e4 | 478 | { |
64ca5aba | 479 | struct syncppp *ap = from_tasklet(ap, t, tsk); |
1da177e4 LT |
480 | struct sk_buff *skb; |
481 | ||
482 | /* process received packets */ | |
483 | while ((skb = skb_dequeue(&ap->rqueue)) != NULL) { | |
484 | if (skb->len == 0) { | |
485 | /* zero length buffers indicate error */ | |
486 | ppp_input_error(&ap->chan, 0); | |
487 | kfree_skb(skb); | |
488 | } | |
489 | else | |
490 | ppp_input(&ap->chan, skb); | |
491 | } | |
492 | ||
493 | /* try to push more stuff out */ | |
494 | if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_sync_push(ap)) | |
495 | ppp_output_wakeup(&ap->chan); | |
496 | } | |
497 | ||
498 | /* | |
499 | * Procedures for encapsulation and framing. | |
500 | */ | |
501 | ||
3c582b30 | 502 | static struct sk_buff* |
1da177e4 LT |
503 | ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *skb) |
504 | { | |
505 | int proto; | |
506 | unsigned char *data; | |
507 | int islcp; | |
508 | ||
509 | data = skb->data; | |
96545aeb | 510 | proto = get_unaligned_be16(data); |
1da177e4 LT |
511 | |
512 | /* LCP packets with codes between 1 (configure-request) | |
513 | * and 7 (code-reject) must be sent as though no options | |
514 | * have been negotiated. | |
515 | */ | |
516 | islcp = proto == PPP_LCP && 1 <= data[2] && data[2] <= 7; | |
517 | ||
518 | /* compress protocol field if option enabled */ | |
519 | if (data[0] == 0 && (ap->flags & SC_COMP_PROT) && !islcp) | |
520 | skb_pull(skb,1); | |
521 | ||
522 | /* prepend address/control fields if necessary */ | |
523 | if ((ap->flags & SC_COMP_AC) == 0 || islcp) { | |
524 | if (skb_headroom(skb) < 2) { | |
525 | struct sk_buff *npkt = dev_alloc_skb(skb->len + 2); | |
526 | if (npkt == NULL) { | |
527 | kfree_skb(skb); | |
528 | return NULL; | |
529 | } | |
530 | skb_reserve(npkt,2); | |
d626f62b ACM |
531 | skb_copy_from_linear_data(skb, |
532 | skb_put(npkt, skb->len), skb->len); | |
968d7018 | 533 | consume_skb(skb); |
1da177e4 LT |
534 | skb = npkt; |
535 | } | |
536 | skb_push(skb,2); | |
537 | skb->data[0] = PPP_ALLSTATIONS; | |
538 | skb->data[1] = PPP_UI; | |
539 | } | |
540 | ||
541 | ap->last_xmit = jiffies; | |
542 | ||
543 | if (skb && ap->flags & SC_LOG_OUTPKT) | |
544 | ppp_print_buffer ("send buffer", skb->data, skb->len); | |
545 | ||
546 | return skb; | |
547 | } | |
548 | ||
549 | /* | |
550 | * Transmit-side routines. | |
551 | */ | |
552 | ||
553 | /* | |
554 | * Send a packet to the peer over an sync tty line. | |
555 | * Returns 1 iff the packet was accepted. | |
556 | * If the packet was not accepted, we will call ppp_output_wakeup | |
557 | * at some later time. | |
558 | */ | |
559 | static int | |
560 | ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb) | |
561 | { | |
562 | struct syncppp *ap = chan->private; | |
563 | ||
564 | ppp_sync_push(ap); | |
565 | ||
566 | if (test_and_set_bit(XMIT_FULL, &ap->xmit_flags)) | |
567 | return 0; /* already full */ | |
568 | skb = ppp_sync_txmunge(ap, skb); | |
569 | if (skb != NULL) | |
570 | ap->tpkt = skb; | |
571 | else | |
572 | clear_bit(XMIT_FULL, &ap->xmit_flags); | |
573 | ||
574 | ppp_sync_push(ap); | |
575 | return 1; | |
576 | } | |
577 | ||
578 | /* | |
579 | * Push as much data as possible out to the tty. | |
580 | */ | |
581 | static int | |
582 | ppp_sync_push(struct syncppp *ap) | |
583 | { | |
584 | int sent, done = 0; | |
585 | struct tty_struct *tty = ap->tty; | |
586 | int tty_stuffed = 0; | |
587 | ||
588 | if (!spin_trylock_bh(&ap->xmit_lock)) | |
589 | return 0; | |
590 | for (;;) { | |
591 | if (test_and_clear_bit(XMIT_WAKEUP, &ap->xmit_flags)) | |
592 | tty_stuffed = 0; | |
cd228d54 | 593 | if (!tty_stuffed && ap->tpkt) { |
1da177e4 | 594 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
f34d7a5b | 595 | sent = tty->ops->write(tty, ap->tpkt->data, ap->tpkt->len); |
1da177e4 LT |
596 | if (sent < 0) |
597 | goto flush; /* error, e.g. loss of CD */ | |
598 | if (sent < ap->tpkt->len) { | |
599 | tty_stuffed = 1; | |
600 | } else { | |
968d7018 | 601 | consume_skb(ap->tpkt); |
1da177e4 LT |
602 | ap->tpkt = NULL; |
603 | clear_bit(XMIT_FULL, &ap->xmit_flags); | |
604 | done = 1; | |
605 | } | |
606 | continue; | |
607 | } | |
608 | /* haven't made any progress */ | |
609 | spin_unlock_bh(&ap->xmit_lock); | |
8e95a202 JP |
610 | if (!(test_bit(XMIT_WAKEUP, &ap->xmit_flags) || |
611 | (!tty_stuffed && ap->tpkt))) | |
1da177e4 LT |
612 | break; |
613 | if (!spin_trylock_bh(&ap->xmit_lock)) | |
614 | break; | |
615 | } | |
616 | return done; | |
617 | ||
618 | flush: | |
cd228d54 | 619 | if (ap->tpkt) { |
1da177e4 LT |
620 | kfree_skb(ap->tpkt); |
621 | ap->tpkt = NULL; | |
622 | clear_bit(XMIT_FULL, &ap->xmit_flags); | |
623 | done = 1; | |
624 | } | |
625 | spin_unlock_bh(&ap->xmit_lock); | |
626 | return done; | |
627 | } | |
628 | ||
629 | /* | |
630 | * Flush output from our internal buffers. | |
631 | * Called for the TCFLSH ioctl. | |
632 | */ | |
633 | static void | |
634 | ppp_sync_flush_output(struct syncppp *ap) | |
635 | { | |
636 | int done = 0; | |
637 | ||
638 | spin_lock_bh(&ap->xmit_lock); | |
639 | if (ap->tpkt != NULL) { | |
640 | kfree_skb(ap->tpkt); | |
641 | ap->tpkt = NULL; | |
642 | clear_bit(XMIT_FULL, &ap->xmit_flags); | |
643 | done = 1; | |
644 | } | |
645 | spin_unlock_bh(&ap->xmit_lock); | |
646 | if (done) | |
647 | ppp_output_wakeup(&ap->chan); | |
648 | } | |
649 | ||
650 | /* | |
651 | * Receive-side routines. | |
652 | */ | |
653 | ||
654 | /* called when the tty driver has data for us. | |
655 | * | |
656 | * Data is frame oriented: each call to ppp_sync_input is considered | |
657 | * a whole frame. If the 1st flag byte is non-zero then the whole | |
658 | * frame is considered to be in error and is tossed. | |
659 | */ | |
660 | static void | |
892bc209 | 661 | ppp_sync_input(struct syncppp *ap, const u8 *buf, const u8 *flags, int count) |
1da177e4 LT |
662 | { |
663 | struct sk_buff *skb; | |
664 | unsigned char *p; | |
665 | ||
666 | if (count == 0) | |
667 | return; | |
668 | ||
669 | if (ap->flags & SC_LOG_INPKT) | |
670 | ppp_print_buffer ("receive buffer", buf, count); | |
671 | ||
672 | /* stuff the chars in the skb */ | |
cd228d54 JP |
673 | skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2); |
674 | if (!skb) { | |
1da177e4 LT |
675 | printk(KERN_ERR "PPPsync: no memory (input pkt)\n"); |
676 | goto err; | |
677 | } | |
678 | /* Try to get the payload 4-byte aligned */ | |
679 | if (buf[0] != PPP_ALLSTATIONS) | |
680 | skb_reserve(skb, 2 + (buf[0] & 1)); | |
681 | ||
cd228d54 | 682 | if (flags && *flags) { |
1da177e4 LT |
683 | /* error flag set, ignore frame */ |
684 | goto err; | |
685 | } else if (count > skb_tailroom(skb)) { | |
686 | /* packet overflowed MRU */ | |
687 | goto err; | |
688 | } | |
689 | ||
b952f4df | 690 | skb_put_data(skb, buf, count); |
1da177e4 LT |
691 | |
692 | /* strip address/control field if present */ | |
693 | p = skb->data; | |
71963985 | 694 | if (skb->len >= 2 && p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) { |
1da177e4 LT |
695 | /* chop off address/control */ |
696 | if (skb->len < 3) | |
697 | goto err; | |
698 | p = skb_pull(skb, 2); | |
699 | } | |
700 | ||
7fb1b8ca SP |
701 | /* PPP packet length should be >= 2 bytes when protocol field is not |
702 | * compressed. | |
703 | */ | |
704 | if (!(p[0] & 0x01) && skb->len < 2) | |
1da177e4 LT |
705 | goto err; |
706 | ||
707 | /* queue the frame to be processed */ | |
708 | skb_queue_tail(&ap->rqueue, skb); | |
709 | return; | |
710 | ||
711 | err: | |
712 | /* queue zero length packet as error indication */ | |
713 | if (skb || (skb = dev_alloc_skb(0))) { | |
714 | skb_trim(skb, 0); | |
715 | skb_queue_tail(&ap->rqueue, skb); | |
716 | } | |
717 | } | |
718 | ||
719 | static void __exit | |
720 | ppp_sync_cleanup(void) | |
721 | { | |
357a6a87 | 722 | tty_unregister_ldisc(&ppp_sync_ldisc); |
1da177e4 LT |
723 | } |
724 | ||
725 | module_init(ppp_sync_init); | |
726 | module_exit(ppp_sync_cleanup); | |
e1e5ef2a | 727 | MODULE_DESCRIPTION("PPP synchronous TTY channel module"); |
1da177e4 LT |
728 | MODULE_LICENSE("GPL"); |
729 | MODULE_ALIAS_LDISC(N_SYNC_PPP); |