blob: 2573f525f11c31ced737e750fefc66807bbbfc65 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * PPP synchronous tty channel driver for Linux.
3 *
4 * This is a ppp channel driver that can be used with tty device drivers
5 * that are frame oriented, such as synchronous HDLC devices.
6 *
7 * Complete PPP frames without encoding/decoding are exchanged between
8 * the channel driver and the device driver.
Jeff Garzik6aa20a22006-09-13 13:24:59 -04009 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 * The async map IOCTL codes are implemented to keep the user mode
11 * applications happy if they call them. Synchronous PPP does not use
12 * the async maps.
13 *
14 * Copyright 1999 Paul Mackerras.
15 *
16 * Also touched by the grubby hands of Paul Fulghum paulkf@microgate.com
17 *
18 * This program is free software; you can redistribute it and/or
19 * modify it under the terms of the GNU General Public License
20 * as published by the Free Software Foundation; either version
21 * 2 of the License, or (at your option) any later version.
22 *
23 * This driver provides the encapsulation and framing for sending
24 * and receiving PPP frames over sync serial lines. It relies on
25 * the generic PPP layer to give it frames to send and to process
26 * received frames. It implements the PPP line discipline.
27 *
28 * Part of the code in this driver was inspired by the old async-only
29 * PPP driver, written by Michael Callahan and Al Longyear, and
30 * subsequently hacked by Paul Mackerras.
31 *
32 * ==FILEVERSION 20040616==
33 */
34
35#include <linux/module.h>
36#include <linux/kernel.h>
37#include <linux/skbuff.h>
38#include <linux/tty.h>
39#include <linux/netdevice.h>
40#include <linux/poll.h>
41#include <linux/ppp_defs.h>
42#include <linux/if_ppp.h>
43#include <linux/ppp_channel.h>
44#include <linux/spinlock.h>
Matthias Kaehlcke5e41fb82007-12-14 11:32:48 -080045#include <linux/completion.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070046#include <linux/init.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090047#include <linux/slab.h>
Changli Gao96545ae2011-01-06 13:37:36 +000048#include <asm/unaligned.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070049#include <asm/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
51#define PPP_VERSION "2.4.2"
52
53/* Structure for storing local state. */
54struct syncppp {
55 struct tty_struct *tty;
56 unsigned int flags;
57 unsigned int rbits;
58 int mru;
59 spinlock_t xmit_lock;
60 spinlock_t recv_lock;
61 unsigned long xmit_flags;
62 u32 xaccm[8];
63 u32 raccm;
64 unsigned int bytes_sent;
65 unsigned int bytes_rcvd;
66
67 struct sk_buff *tpkt;
68 unsigned long last_xmit;
69
70 struct sk_buff_head rqueue;
71
72 struct tasklet_struct tsk;
73
74 atomic_t refcnt;
Matthias Kaehlcke5e41fb82007-12-14 11:32:48 -080075 struct completion dead_cmp;
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 struct ppp_channel chan; /* interface to generic ppp layer */
77};
78
79/* Bit numbers in xmit_flags */
80#define XMIT_WAKEUP 0
81#define XMIT_FULL 1
82
83/* Bits in rbits */
84#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
85
86#define PPPSYNC_MAX_RQLEN 32 /* arbitrary */
87
88/*
89 * Prototypes.
90 */
91static struct sk_buff* ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *);
92static int ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb);
93static int ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd,
94 unsigned long arg);
95static void ppp_sync_process(unsigned long arg);
96static int ppp_sync_push(struct syncppp *ap);
97static void ppp_sync_flush_output(struct syncppp *ap);
98static void ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
99 char *flags, int count);
100
stephen hemmingerd7100da2010-08-04 07:34:36 +0000101static const struct ppp_channel_ops sync_ops = {
102 .start_xmit = ppp_sync_send,
103 .ioctl = ppp_sync_ioctl,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104};
105
106/*
107 * Utility procedures to print a buffer in hex/ascii
108 */
109static void
110ppp_print_hex (register __u8 * out, const __u8 * in, int count)
111{
112 register __u8 next_ch;
Arjan van de Venf71e1302006-03-03 21:33:57 -0500113 static const char hex[] = "0123456789ABCDEF";
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114
115 while (count-- > 0) {
116 next_ch = *in++;
117 *out++ = hex[(next_ch >> 4) & 0x0F];
118 *out++ = hex[next_ch & 0x0F];
119 ++out;
120 }
121}
122
123static void
124ppp_print_char (register __u8 * out, const __u8 * in, int count)
125{
126 register __u8 next_ch;
127
128 while (count-- > 0) {
129 next_ch = *in++;
130
131 if (next_ch < 0x20 || next_ch > 0x7e)
132 *out++ = '.';
133 else {
134 *out++ = next_ch;
135 if (next_ch == '%') /* printk/syslogd has a bug !! */
136 *out++ = '%';
137 }
138 }
139 *out = '\0';
140}
141
142static void
143ppp_print_buffer (const char *name, const __u8 *buf, int count)
144{
145 __u8 line[44];
146
147 if (name != NULL)
148 printk(KERN_DEBUG "ppp_synctty: %s, count = %d\n", name, count);
149
150 while (count > 8) {
151 memset (line, 32, 44);
152 ppp_print_hex (line, buf, 8);
153 ppp_print_char (&line[8 * 3], buf, 8);
154 printk(KERN_DEBUG "%s\n", line);
155 count -= 8;
156 buf += 8;
157 }
158
159 if (count > 0) {
160 memset (line, 32, 44);
161 ppp_print_hex (line, buf, count);
162 ppp_print_char (&line[8 * 3], buf, count);
163 printk(KERN_DEBUG "%s\n", line);
164 }
165}
166
167
168/*
169 * Routines implementing the synchronous PPP line discipline.
170 */
171
172/*
173 * We have a potential race on dereferencing tty->disc_data,
174 * because the tty layer provides no locking at all - thus one
175 * cpu could be running ppp_synctty_receive while another
176 * calls ppp_synctty_close, which zeroes tty->disc_data and
177 * frees the memory that ppp_synctty_receive is using. The best
178 * way to fix this is to use a rwlock in the tty struct, but for now
179 * we use a single global rwlock for all ttys in ppp line discipline.
180 *
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300181 * FIXME: Fixed in tty_io nowadays.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 */
183static DEFINE_RWLOCK(disc_data_lock);
184
185static struct syncppp *sp_get(struct tty_struct *tty)
186{
187 struct syncppp *ap;
188
189 read_lock(&disc_data_lock);
190 ap = tty->disc_data;
191 if (ap != NULL)
192 atomic_inc(&ap->refcnt);
193 read_unlock(&disc_data_lock);
194 return ap;
195}
196
197static void sp_put(struct syncppp *ap)
198{
199 if (atomic_dec_and_test(&ap->refcnt))
Matthias Kaehlcke5e41fb82007-12-14 11:32:48 -0800200 complete(&ap->dead_cmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201}
202
203/*
204 * Called when a tty is put into sync-PPP line discipline.
205 */
206static int
207ppp_sync_open(struct tty_struct *tty)
208{
209 struct syncppp *ap;
210 int err;
Gabriele Paoloni9c705262009-03-13 16:09:12 -0700211 int speed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212
Alan Coxf34d7a52008-04-30 00:54:13 -0700213 if (tty->ops->write == NULL)
214 return -EOPNOTSUPP;
215
Yoann Padioleaudd00cc42007-07-19 01:49:03 -0700216 ap = kzalloc(sizeof(*ap), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 err = -ENOMEM;
Joe Perchescd228d52007-11-12 18:07:31 -0800218 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 goto out;
220
221 /* initialize the syncppp structure */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 ap->tty = tty;
223 ap->mru = PPP_MRU;
224 spin_lock_init(&ap->xmit_lock);
225 spin_lock_init(&ap->recv_lock);
226 ap->xaccm[0] = ~0U;
227 ap->xaccm[3] = 0x60000000U;
228 ap->raccm = ~0U;
229
230 skb_queue_head_init(&ap->rqueue);
231 tasklet_init(&ap->tsk, ppp_sync_process, (unsigned long) ap);
232
233 atomic_set(&ap->refcnt, 1);
Matthias Kaehlcke5e41fb82007-12-14 11:32:48 -0800234 init_completion(&ap->dead_cmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235
236 ap->chan.private = ap;
237 ap->chan.ops = &sync_ops;
238 ap->chan.mtu = PPP_MRU;
239 ap->chan.hdrlen = 2; /* for A/C bytes */
Gabriele Paoloni9c705262009-03-13 16:09:12 -0700240 speed = tty_get_baud_rate(tty);
241 ap->chan.speed = speed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 err = ppp_register_channel(&ap->chan);
243 if (err)
244 goto out_free;
245
246 tty->disc_data = ap;
Alan Cox33f0f882006-01-09 20:54:13 -0800247 tty->receive_room = 65536;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248 return 0;
249
250 out_free:
251 kfree(ap);
252 out:
253 return err;
254}
255
256/*
257 * Called when the tty is put into another line discipline
258 * or it hangs up. We have to wait for any cpu currently
259 * executing in any of the other ppp_synctty_* routines to
260 * finish before we can call ppp_unregister_channel and free
261 * the syncppp struct. This routine must be called from
262 * process context, not interrupt or softirq context.
263 */
264static void
265ppp_sync_close(struct tty_struct *tty)
266{
267 struct syncppp *ap;
268
269 write_lock_irq(&disc_data_lock);
270 ap = tty->disc_data;
271 tty->disc_data = NULL;
272 write_unlock_irq(&disc_data_lock);
Joe Perchescd228d52007-11-12 18:07:31 -0800273 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 return;
275
276 /*
277 * We have now ensured that nobody can start using ap from now
278 * on, but we have to wait for all existing users to finish.
279 * Note that ppp_unregister_channel ensures that no calls to
280 * our channel ops (i.e. ppp_sync_send/ioctl) are in progress
281 * by the time it returns.
282 */
283 if (!atomic_dec_and_test(&ap->refcnt))
Matthias Kaehlcke5e41fb82007-12-14 11:32:48 -0800284 wait_for_completion(&ap->dead_cmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 tasklet_kill(&ap->tsk);
286
287 ppp_unregister_channel(&ap->chan);
288 skb_queue_purge(&ap->rqueue);
Wei Yongjun1d2f8c92009-02-25 00:16:08 +0000289 kfree_skb(ap->tpkt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 kfree(ap);
291}
292
293/*
294 * Called on tty hangup in process context.
295 *
296 * Wait for I/O to driver to complete and unregister PPP channel.
297 * This is already done by the close routine, so just call that.
298 */
299static int ppp_sync_hangup(struct tty_struct *tty)
300{
301 ppp_sync_close(tty);
302 return 0;
303}
304
305/*
306 * Read does nothing - no data is ever available this way.
307 * Pppd reads and writes packets via /dev/ppp instead.
308 */
309static ssize_t
310ppp_sync_read(struct tty_struct *tty, struct file *file,
311 unsigned char __user *buf, size_t count)
312{
313 return -EAGAIN;
314}
315
316/*
317 * Write on the tty does nothing, the packets all come in
318 * from the ppp generic stuff.
319 */
320static ssize_t
321ppp_sync_write(struct tty_struct *tty, struct file *file,
322 const unsigned char *buf, size_t count)
323{
324 return -EAGAIN;
325}
326
327static int
328ppp_synctty_ioctl(struct tty_struct *tty, struct file *file,
329 unsigned int cmd, unsigned long arg)
330{
331 struct syncppp *ap = sp_get(tty);
332 int __user *p = (int __user *)arg;
333 int err, val;
334
Joe Perchescd228d52007-11-12 18:07:31 -0800335 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 return -ENXIO;
337 err = -EFAULT;
338 switch (cmd) {
339 case PPPIOCGCHAN:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 err = -EFAULT;
341 if (put_user(ppp_channel_index(&ap->chan), p))
342 break;
343 err = 0;
344 break;
345
346 case PPPIOCGUNIT:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 err = -EFAULT;
348 if (put_user(ppp_unit_number(&ap->chan), p))
349 break;
350 err = 0;
351 break;
352
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353 case TCFLSH:
354 /* flush our buffers and the serial port's buffer */
355 if (arg == TCIOFLUSH || arg == TCOFLUSH)
356 ppp_sync_flush_output(ap);
Alan Coxd0127532007-11-07 01:27:34 -0800357 err = tty_perform_flush(tty, arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 break;
359
360 case FIONREAD:
361 val = 0;
362 if (put_user(val, p))
363 break;
364 err = 0;
365 break;
366
367 default:
Alan Coxd0127532007-11-07 01:27:34 -0800368 err = tty_mode_ioctl(tty, file, cmd, arg);
369 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370 }
371
372 sp_put(ap);
373 return err;
374}
375
376/* No kernel lock - fine */
377static unsigned int
378ppp_sync_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
379{
380 return 0;
381}
382
Tilman Schmidt92d326f2009-10-01 04:28:44 +0000383/* May sleep, don't call from interrupt level or with interrupts disabled */
Linus Torvalds55db4c62011-06-04 06:33:24 +0900384static void
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385ppp_sync_receive(struct tty_struct *tty, const unsigned char *buf,
386 char *cflags, int count)
387{
388 struct syncppp *ap = sp_get(tty);
389 unsigned long flags;
390
Joe Perchescd228d52007-11-12 18:07:31 -0800391 if (!ap)
Linus Torvalds55db4c62011-06-04 06:33:24 +0900392 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393 spin_lock_irqsave(&ap->recv_lock, flags);
394 ppp_sync_input(ap, buf, cflags, count);
395 spin_unlock_irqrestore(&ap->recv_lock, flags);
David S. Millerb03efcf2005-07-08 14:57:23 -0700396 if (!skb_queue_empty(&ap->rqueue))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 tasklet_schedule(&ap->tsk);
398 sp_put(ap);
Linus Torvalds4a21b8c2009-07-16 09:14:23 -0700399 tty_unthrottle(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400}
401
402static void
403ppp_sync_wakeup(struct tty_struct *tty)
404{
405 struct syncppp *ap = sp_get(tty);
406
407 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
Joe Perchescd228d52007-11-12 18:07:31 -0800408 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 return;
410 set_bit(XMIT_WAKEUP, &ap->xmit_flags);
411 tasklet_schedule(&ap->tsk);
412 sp_put(ap);
413}
414
415
Alan Coxa352def2008-07-16 21:53:12 +0100416static struct tty_ldisc_ops ppp_sync_ldisc = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 .owner = THIS_MODULE,
418 .magic = TTY_LDISC_MAGIC,
419 .name = "pppsync",
420 .open = ppp_sync_open,
421 .close = ppp_sync_close,
422 .hangup = ppp_sync_hangup,
423 .read = ppp_sync_read,
424 .write = ppp_sync_write,
425 .ioctl = ppp_synctty_ioctl,
426 .poll = ppp_sync_poll,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 .receive_buf = ppp_sync_receive,
428 .write_wakeup = ppp_sync_wakeup,
429};
430
431static int __init
432ppp_sync_init(void)
433{
434 int err;
435
436 err = tty_register_ldisc(N_SYNC_PPP, &ppp_sync_ldisc);
437 if (err != 0)
438 printk(KERN_ERR "PPP_sync: error %d registering line disc.\n",
439 err);
440 return err;
441}
442
443/*
444 * The following routines provide the PPP channel interface.
445 */
446static int
447ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg)
448{
449 struct syncppp *ap = chan->private;
450 int err, val;
451 u32 accm[8];
452 void __user *argp = (void __user *)arg;
453 u32 __user *p = argp;
454
455 err = -EFAULT;
456 switch (cmd) {
457 case PPPIOCGFLAGS:
458 val = ap->flags | ap->rbits;
459 if (put_user(val, (int __user *) argp))
460 break;
461 err = 0;
462 break;
463 case PPPIOCSFLAGS:
464 if (get_user(val, (int __user *) argp))
465 break;
466 ap->flags = val & ~SC_RCV_BITS;
467 spin_lock_irq(&ap->recv_lock);
468 ap->rbits = val & SC_RCV_BITS;
469 spin_unlock_irq(&ap->recv_lock);
470 err = 0;
471 break;
472
473 case PPPIOCGASYNCMAP:
474 if (put_user(ap->xaccm[0], p))
475 break;
476 err = 0;
477 break;
478 case PPPIOCSASYNCMAP:
479 if (get_user(ap->xaccm[0], p))
480 break;
481 err = 0;
482 break;
483
484 case PPPIOCGRASYNCMAP:
485 if (put_user(ap->raccm, p))
486 break;
487 err = 0;
488 break;
489 case PPPIOCSRASYNCMAP:
490 if (get_user(ap->raccm, p))
491 break;
492 err = 0;
493 break;
494
495 case PPPIOCGXASYNCMAP:
496 if (copy_to_user(argp, ap->xaccm, sizeof(ap->xaccm)))
497 break;
498 err = 0;
499 break;
500 case PPPIOCSXASYNCMAP:
501 if (copy_from_user(accm, argp, sizeof(accm)))
502 break;
503 accm[2] &= ~0x40000000U; /* can't escape 0x5e */
504 accm[3] |= 0x60000000U; /* must escape 0x7d, 0x7e */
505 memcpy(ap->xaccm, accm, sizeof(ap->xaccm));
506 err = 0;
507 break;
508
509 case PPPIOCGMRU:
510 if (put_user(ap->mru, (int __user *) argp))
511 break;
512 err = 0;
513 break;
514 case PPPIOCSMRU:
515 if (get_user(val, (int __user *) argp))
516 break;
517 if (val < PPP_MRU)
518 val = PPP_MRU;
519 ap->mru = val;
520 err = 0;
521 break;
522
523 default:
524 err = -ENOTTY;
525 }
526 return err;
527}
528
529/*
530 * This is called at softirq level to deliver received packets
531 * to the ppp_generic code, and to tell the ppp_generic code
532 * if we can accept more output now.
533 */
534static void ppp_sync_process(unsigned long arg)
535{
536 struct syncppp *ap = (struct syncppp *) arg;
537 struct sk_buff *skb;
538
539 /* process received packets */
540 while ((skb = skb_dequeue(&ap->rqueue)) != NULL) {
541 if (skb->len == 0) {
542 /* zero length buffers indicate error */
543 ppp_input_error(&ap->chan, 0);
544 kfree_skb(skb);
545 }
546 else
547 ppp_input(&ap->chan, skb);
548 }
549
550 /* try to push more stuff out */
551 if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_sync_push(ap))
552 ppp_output_wakeup(&ap->chan);
553}
554
555/*
556 * Procedures for encapsulation and framing.
557 */
558
Stephen Hemminger3c582b32008-01-23 20:54:07 -0800559static struct sk_buff*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *skb)
561{
562 int proto;
563 unsigned char *data;
564 int islcp;
565
566 data = skb->data;
Changli Gao96545ae2011-01-06 13:37:36 +0000567 proto = get_unaligned_be16(data);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568
569 /* LCP packets with codes between 1 (configure-request)
570 * and 7 (code-reject) must be sent as though no options
571 * have been negotiated.
572 */
573 islcp = proto == PPP_LCP && 1 <= data[2] && data[2] <= 7;
574
575 /* compress protocol field if option enabled */
576 if (data[0] == 0 && (ap->flags & SC_COMP_PROT) && !islcp)
577 skb_pull(skb,1);
578
579 /* prepend address/control fields if necessary */
580 if ((ap->flags & SC_COMP_AC) == 0 || islcp) {
581 if (skb_headroom(skb) < 2) {
582 struct sk_buff *npkt = dev_alloc_skb(skb->len + 2);
583 if (npkt == NULL) {
584 kfree_skb(skb);
585 return NULL;
586 }
587 skb_reserve(npkt,2);
Arnaldo Carvalho de Melod626f622007-03-27 18:55:52 -0300588 skb_copy_from_linear_data(skb,
589 skb_put(npkt, skb->len), skb->len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590 kfree_skb(skb);
591 skb = npkt;
592 }
593 skb_push(skb,2);
594 skb->data[0] = PPP_ALLSTATIONS;
595 skb->data[1] = PPP_UI;
596 }
597
598 ap->last_xmit = jiffies;
599
600 if (skb && ap->flags & SC_LOG_OUTPKT)
601 ppp_print_buffer ("send buffer", skb->data, skb->len);
602
603 return skb;
604}
605
606/*
607 * Transmit-side routines.
608 */
609
610/*
611 * Send a packet to the peer over an sync tty line.
612 * Returns 1 iff the packet was accepted.
613 * If the packet was not accepted, we will call ppp_output_wakeup
614 * at some later time.
615 */
616static int
617ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb)
618{
619 struct syncppp *ap = chan->private;
620
621 ppp_sync_push(ap);
622
623 if (test_and_set_bit(XMIT_FULL, &ap->xmit_flags))
624 return 0; /* already full */
625 skb = ppp_sync_txmunge(ap, skb);
626 if (skb != NULL)
627 ap->tpkt = skb;
628 else
629 clear_bit(XMIT_FULL, &ap->xmit_flags);
630
631 ppp_sync_push(ap);
632 return 1;
633}
634
635/*
636 * Push as much data as possible out to the tty.
637 */
638static int
639ppp_sync_push(struct syncppp *ap)
640{
641 int sent, done = 0;
642 struct tty_struct *tty = ap->tty;
643 int tty_stuffed = 0;
644
645 if (!spin_trylock_bh(&ap->xmit_lock))
646 return 0;
647 for (;;) {
648 if (test_and_clear_bit(XMIT_WAKEUP, &ap->xmit_flags))
649 tty_stuffed = 0;
Joe Perchescd228d52007-11-12 18:07:31 -0800650 if (!tty_stuffed && ap->tpkt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
Alan Coxf34d7a52008-04-30 00:54:13 -0700652 sent = tty->ops->write(tty, ap->tpkt->data, ap->tpkt->len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 if (sent < 0)
654 goto flush; /* error, e.g. loss of CD */
655 if (sent < ap->tpkt->len) {
656 tty_stuffed = 1;
657 } else {
658 kfree_skb(ap->tpkt);
659 ap->tpkt = NULL;
660 clear_bit(XMIT_FULL, &ap->xmit_flags);
661 done = 1;
662 }
663 continue;
664 }
665 /* haven't made any progress */
666 spin_unlock_bh(&ap->xmit_lock);
Joe Perches8e95a202009-12-03 07:58:21 +0000667 if (!(test_bit(XMIT_WAKEUP, &ap->xmit_flags) ||
668 (!tty_stuffed && ap->tpkt)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669 break;
670 if (!spin_trylock_bh(&ap->xmit_lock))
671 break;
672 }
673 return done;
674
675flush:
Joe Perchescd228d52007-11-12 18:07:31 -0800676 if (ap->tpkt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677 kfree_skb(ap->tpkt);
678 ap->tpkt = NULL;
679 clear_bit(XMIT_FULL, &ap->xmit_flags);
680 done = 1;
681 }
682 spin_unlock_bh(&ap->xmit_lock);
683 return done;
684}
685
686/*
687 * Flush output from our internal buffers.
688 * Called for the TCFLSH ioctl.
689 */
690static void
691ppp_sync_flush_output(struct syncppp *ap)
692{
693 int done = 0;
694
695 spin_lock_bh(&ap->xmit_lock);
696 if (ap->tpkt != NULL) {
697 kfree_skb(ap->tpkt);
698 ap->tpkt = NULL;
699 clear_bit(XMIT_FULL, &ap->xmit_flags);
700 done = 1;
701 }
702 spin_unlock_bh(&ap->xmit_lock);
703 if (done)
704 ppp_output_wakeup(&ap->chan);
705}
706
707/*
708 * Receive-side routines.
709 */
710
711/* called when the tty driver has data for us.
712 *
713 * Data is frame oriented: each call to ppp_sync_input is considered
714 * a whole frame. If the 1st flag byte is non-zero then the whole
715 * frame is considered to be in error and is tossed.
716 */
717static void
718ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
719 char *flags, int count)
720{
721 struct sk_buff *skb;
722 unsigned char *p;
723
724 if (count == 0)
725 return;
726
727 if (ap->flags & SC_LOG_INPKT)
728 ppp_print_buffer ("receive buffer", buf, count);
729
730 /* stuff the chars in the skb */
Joe Perchescd228d52007-11-12 18:07:31 -0800731 skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2);
732 if (!skb) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733 printk(KERN_ERR "PPPsync: no memory (input pkt)\n");
734 goto err;
735 }
736 /* Try to get the payload 4-byte aligned */
737 if (buf[0] != PPP_ALLSTATIONS)
738 skb_reserve(skb, 2 + (buf[0] & 1));
739
Joe Perchescd228d52007-11-12 18:07:31 -0800740 if (flags && *flags) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741 /* error flag set, ignore frame */
742 goto err;
743 } else if (count > skb_tailroom(skb)) {
744 /* packet overflowed MRU */
745 goto err;
746 }
747
748 p = skb_put(skb, count);
749 memcpy(p, buf, count);
750
751 /* strip address/control field if present */
752 p = skb->data;
753 if (p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) {
754 /* chop off address/control */
755 if (skb->len < 3)
756 goto err;
757 p = skb_pull(skb, 2);
758 }
759
760 /* decompress protocol field if compressed */
761 if (p[0] & 1) {
762 /* protocol is compressed */
763 skb_push(skb, 1)[0] = 0;
764 } else if (skb->len < 2)
765 goto err;
766
767 /* queue the frame to be processed */
768 skb_queue_tail(&ap->rqueue, skb);
769 return;
770
771err:
772 /* queue zero length packet as error indication */
773 if (skb || (skb = dev_alloc_skb(0))) {
774 skb_trim(skb, 0);
775 skb_queue_tail(&ap->rqueue, skb);
776 }
777}
778
779static void __exit
780ppp_sync_cleanup(void)
781{
Alexey Dobriyan64ccd712005-06-23 00:10:33 -0700782 if (tty_unregister_ldisc(N_SYNC_PPP) != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783 printk(KERN_ERR "failed to unregister Sync PPP line discipline\n");
784}
785
786module_init(ppp_sync_init);
787module_exit(ppp_sync_cleanup);
788MODULE_LICENSE("GPL");
789MODULE_ALIAS_LDISC(N_SYNC_PPP);