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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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070048#include <asm/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070049
50#define PPP_VERSION "2.4.2"
51
52/* Structure for storing local state. */
53struct syncppp {
54 struct tty_struct *tty;
55 unsigned int flags;
56 unsigned int rbits;
57 int mru;
58 spinlock_t xmit_lock;
59 spinlock_t recv_lock;
60 unsigned long xmit_flags;
61 u32 xaccm[8];
62 u32 raccm;
63 unsigned int bytes_sent;
64 unsigned int bytes_rcvd;
65
66 struct sk_buff *tpkt;
67 unsigned long last_xmit;
68
69 struct sk_buff_head rqueue;
70
71 struct tasklet_struct tsk;
72
73 atomic_t refcnt;
Matthias Kaehlcke5e41fb82007-12-14 11:32:48 -080074 struct completion dead_cmp;
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 struct ppp_channel chan; /* interface to generic ppp layer */
76};
77
78/* Bit numbers in xmit_flags */
79#define XMIT_WAKEUP 0
80#define XMIT_FULL 1
81
82/* Bits in rbits */
83#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
84
85#define PPPSYNC_MAX_RQLEN 32 /* arbitrary */
86
87/*
88 * Prototypes.
89 */
90static struct sk_buff* ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *);
91static int ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb);
92static int ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd,
93 unsigned long arg);
94static void ppp_sync_process(unsigned long arg);
95static int ppp_sync_push(struct syncppp *ap);
96static void ppp_sync_flush_output(struct syncppp *ap);
97static void ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
98 char *flags, int count);
99
stephen hemmingerd7100da2010-08-04 07:34:36 +0000100static const struct ppp_channel_ops sync_ops = {
101 .start_xmit = ppp_sync_send,
102 .ioctl = ppp_sync_ioctl,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103};
104
105/*
106 * Utility procedures to print a buffer in hex/ascii
107 */
108static void
109ppp_print_hex (register __u8 * out, const __u8 * in, int count)
110{
111 register __u8 next_ch;
Arjan van de Venf71e1302006-03-03 21:33:57 -0500112 static const char hex[] = "0123456789ABCDEF";
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113
114 while (count-- > 0) {
115 next_ch = *in++;
116 *out++ = hex[(next_ch >> 4) & 0x0F];
117 *out++ = hex[next_ch & 0x0F];
118 ++out;
119 }
120}
121
122static void
123ppp_print_char (register __u8 * out, const __u8 * in, int count)
124{
125 register __u8 next_ch;
126
127 while (count-- > 0) {
128 next_ch = *in++;
129
130 if (next_ch < 0x20 || next_ch > 0x7e)
131 *out++ = '.';
132 else {
133 *out++ = next_ch;
134 if (next_ch == '%') /* printk/syslogd has a bug !! */
135 *out++ = '%';
136 }
137 }
138 *out = '\0';
139}
140
141static void
142ppp_print_buffer (const char *name, const __u8 *buf, int count)
143{
144 __u8 line[44];
145
146 if (name != NULL)
147 printk(KERN_DEBUG "ppp_synctty: %s, count = %d\n", name, count);
148
149 while (count > 8) {
150 memset (line, 32, 44);
151 ppp_print_hex (line, buf, 8);
152 ppp_print_char (&line[8 * 3], buf, 8);
153 printk(KERN_DEBUG "%s\n", line);
154 count -= 8;
155 buf += 8;
156 }
157
158 if (count > 0) {
159 memset (line, 32, 44);
160 ppp_print_hex (line, buf, count);
161 ppp_print_char (&line[8 * 3], buf, count);
162 printk(KERN_DEBUG "%s\n", line);
163 }
164}
165
166
167/*
168 * Routines implementing the synchronous PPP line discipline.
169 */
170
171/*
172 * We have a potential race on dereferencing tty->disc_data,
173 * because the tty layer provides no locking at all - thus one
174 * cpu could be running ppp_synctty_receive while another
175 * calls ppp_synctty_close, which zeroes tty->disc_data and
176 * frees the memory that ppp_synctty_receive is using. The best
177 * way to fix this is to use a rwlock in the tty struct, but for now
178 * we use a single global rwlock for all ttys in ppp line discipline.
179 *
180 * FIXME: Fixed in tty_io nowdays.
181 */
182static DEFINE_RWLOCK(disc_data_lock);
183
184static struct syncppp *sp_get(struct tty_struct *tty)
185{
186 struct syncppp *ap;
187
188 read_lock(&disc_data_lock);
189 ap = tty->disc_data;
190 if (ap != NULL)
191 atomic_inc(&ap->refcnt);
192 read_unlock(&disc_data_lock);
193 return ap;
194}
195
196static void sp_put(struct syncppp *ap)
197{
198 if (atomic_dec_and_test(&ap->refcnt))
Matthias Kaehlcke5e41fb82007-12-14 11:32:48 -0800199 complete(&ap->dead_cmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200}
201
202/*
203 * Called when a tty is put into sync-PPP line discipline.
204 */
205static int
206ppp_sync_open(struct tty_struct *tty)
207{
208 struct syncppp *ap;
209 int err;
Gabriele Paoloni9c705262009-03-13 16:09:12 -0700210 int speed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211
Alan Coxf34d7a52008-04-30 00:54:13 -0700212 if (tty->ops->write == NULL)
213 return -EOPNOTSUPP;
214
Yoann Padioleaudd00cc42007-07-19 01:49:03 -0700215 ap = kzalloc(sizeof(*ap), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 err = -ENOMEM;
Joe Perchescd228d52007-11-12 18:07:31 -0800217 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 goto out;
219
220 /* initialize the syncppp structure */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 ap->tty = tty;
222 ap->mru = PPP_MRU;
223 spin_lock_init(&ap->xmit_lock);
224 spin_lock_init(&ap->recv_lock);
225 ap->xaccm[0] = ~0U;
226 ap->xaccm[3] = 0x60000000U;
227 ap->raccm = ~0U;
228
229 skb_queue_head_init(&ap->rqueue);
230 tasklet_init(&ap->tsk, ppp_sync_process, (unsigned long) ap);
231
232 atomic_set(&ap->refcnt, 1);
Matthias Kaehlcke5e41fb82007-12-14 11:32:48 -0800233 init_completion(&ap->dead_cmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234
235 ap->chan.private = ap;
236 ap->chan.ops = &sync_ops;
237 ap->chan.mtu = PPP_MRU;
238 ap->chan.hdrlen = 2; /* for A/C bytes */
Gabriele Paoloni9c705262009-03-13 16:09:12 -0700239 speed = tty_get_baud_rate(tty);
240 ap->chan.speed = speed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241 err = ppp_register_channel(&ap->chan);
242 if (err)
243 goto out_free;
244
245 tty->disc_data = ap;
Alan Cox33f0f882006-01-09 20:54:13 -0800246 tty->receive_room = 65536;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 return 0;
248
249 out_free:
250 kfree(ap);
251 out:
252 return err;
253}
254
255/*
256 * Called when the tty is put into another line discipline
257 * or it hangs up. We have to wait for any cpu currently
258 * executing in any of the other ppp_synctty_* routines to
259 * finish before we can call ppp_unregister_channel and free
260 * the syncppp struct. This routine must be called from
261 * process context, not interrupt or softirq context.
262 */
263static void
264ppp_sync_close(struct tty_struct *tty)
265{
266 struct syncppp *ap;
267
268 write_lock_irq(&disc_data_lock);
269 ap = tty->disc_data;
270 tty->disc_data = NULL;
271 write_unlock_irq(&disc_data_lock);
Joe Perchescd228d52007-11-12 18:07:31 -0800272 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 return;
274
275 /*
276 * We have now ensured that nobody can start using ap from now
277 * on, but we have to wait for all existing users to finish.
278 * Note that ppp_unregister_channel ensures that no calls to
279 * our channel ops (i.e. ppp_sync_send/ioctl) are in progress
280 * by the time it returns.
281 */
282 if (!atomic_dec_and_test(&ap->refcnt))
Matthias Kaehlcke5e41fb82007-12-14 11:32:48 -0800283 wait_for_completion(&ap->dead_cmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 tasklet_kill(&ap->tsk);
285
286 ppp_unregister_channel(&ap->chan);
287 skb_queue_purge(&ap->rqueue);
Wei Yongjun1d2f8c92009-02-25 00:16:08 +0000288 kfree_skb(ap->tpkt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 kfree(ap);
290}
291
292/*
293 * Called on tty hangup in process context.
294 *
295 * Wait for I/O to driver to complete and unregister PPP channel.
296 * This is already done by the close routine, so just call that.
297 */
298static int ppp_sync_hangup(struct tty_struct *tty)
299{
300 ppp_sync_close(tty);
301 return 0;
302}
303
304/*
305 * Read does nothing - no data is ever available this way.
306 * Pppd reads and writes packets via /dev/ppp instead.
307 */
308static ssize_t
309ppp_sync_read(struct tty_struct *tty, struct file *file,
310 unsigned char __user *buf, size_t count)
311{
312 return -EAGAIN;
313}
314
315/*
316 * Write on the tty does nothing, the packets all come in
317 * from the ppp generic stuff.
318 */
319static ssize_t
320ppp_sync_write(struct tty_struct *tty, struct file *file,
321 const unsigned char *buf, size_t count)
322{
323 return -EAGAIN;
324}
325
326static int
327ppp_synctty_ioctl(struct tty_struct *tty, struct file *file,
328 unsigned int cmd, unsigned long arg)
329{
330 struct syncppp *ap = sp_get(tty);
331 int __user *p = (int __user *)arg;
332 int err, val;
333
Joe Perchescd228d52007-11-12 18:07:31 -0800334 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 return -ENXIO;
336 err = -EFAULT;
337 switch (cmd) {
338 case PPPIOCGCHAN:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 err = -EFAULT;
340 if (put_user(ppp_channel_index(&ap->chan), p))
341 break;
342 err = 0;
343 break;
344
345 case PPPIOCGUNIT:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346 err = -EFAULT;
347 if (put_user(ppp_unit_number(&ap->chan), p))
348 break;
349 err = 0;
350 break;
351
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 case TCFLSH:
353 /* flush our buffers and the serial port's buffer */
354 if (arg == TCIOFLUSH || arg == TCOFLUSH)
355 ppp_sync_flush_output(ap);
Alan Coxd0127532007-11-07 01:27:34 -0800356 err = tty_perform_flush(tty, arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 break;
358
359 case FIONREAD:
360 val = 0;
361 if (put_user(val, p))
362 break;
363 err = 0;
364 break;
365
366 default:
Alan Coxd0127532007-11-07 01:27:34 -0800367 err = tty_mode_ioctl(tty, file, cmd, arg);
368 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 }
370
371 sp_put(ap);
372 return err;
373}
374
375/* No kernel lock - fine */
376static unsigned int
377ppp_sync_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
378{
379 return 0;
380}
381
Tilman Schmidt92d326f2009-10-01 04:28:44 +0000382/* May sleep, don't call from interrupt level or with interrupts disabled */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383static void
384ppp_sync_receive(struct tty_struct *tty, const unsigned char *buf,
385 char *cflags, int count)
386{
387 struct syncppp *ap = sp_get(tty);
388 unsigned long flags;
389
Joe Perchescd228d52007-11-12 18:07:31 -0800390 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 return;
392 spin_lock_irqsave(&ap->recv_lock, flags);
393 ppp_sync_input(ap, buf, cflags, count);
394 spin_unlock_irqrestore(&ap->recv_lock, flags);
David S. Millerb03efcf2005-07-08 14:57:23 -0700395 if (!skb_queue_empty(&ap->rqueue))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396 tasklet_schedule(&ap->tsk);
397 sp_put(ap);
Linus Torvalds4a21b8c2009-07-16 09:14:23 -0700398 tty_unthrottle(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399}
400
401static void
402ppp_sync_wakeup(struct tty_struct *tty)
403{
404 struct syncppp *ap = sp_get(tty);
405
406 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
Joe Perchescd228d52007-11-12 18:07:31 -0800407 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 return;
409 set_bit(XMIT_WAKEUP, &ap->xmit_flags);
410 tasklet_schedule(&ap->tsk);
411 sp_put(ap);
412}
413
414
Alan Coxa352def2008-07-16 21:53:12 +0100415static struct tty_ldisc_ops ppp_sync_ldisc = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 .owner = THIS_MODULE,
417 .magic = TTY_LDISC_MAGIC,
418 .name = "pppsync",
419 .open = ppp_sync_open,
420 .close = ppp_sync_close,
421 .hangup = ppp_sync_hangup,
422 .read = ppp_sync_read,
423 .write = ppp_sync_write,
424 .ioctl = ppp_synctty_ioctl,
425 .poll = ppp_sync_poll,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 .receive_buf = ppp_sync_receive,
427 .write_wakeup = ppp_sync_wakeup,
428};
429
430static int __init
431ppp_sync_init(void)
432{
433 int err;
434
435 err = tty_register_ldisc(N_SYNC_PPP, &ppp_sync_ldisc);
436 if (err != 0)
437 printk(KERN_ERR "PPP_sync: error %d registering line disc.\n",
438 err);
439 return err;
440}
441
442/*
443 * The following routines provide the PPP channel interface.
444 */
445static int
446ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg)
447{
448 struct syncppp *ap = chan->private;
449 int err, val;
450 u32 accm[8];
451 void __user *argp = (void __user *)arg;
452 u32 __user *p = argp;
453
454 err = -EFAULT;
455 switch (cmd) {
456 case PPPIOCGFLAGS:
457 val = ap->flags | ap->rbits;
458 if (put_user(val, (int __user *) argp))
459 break;
460 err = 0;
461 break;
462 case PPPIOCSFLAGS:
463 if (get_user(val, (int __user *) argp))
464 break;
465 ap->flags = val & ~SC_RCV_BITS;
466 spin_lock_irq(&ap->recv_lock);
467 ap->rbits = val & SC_RCV_BITS;
468 spin_unlock_irq(&ap->recv_lock);
469 err = 0;
470 break;
471
472 case PPPIOCGASYNCMAP:
473 if (put_user(ap->xaccm[0], p))
474 break;
475 err = 0;
476 break;
477 case PPPIOCSASYNCMAP:
478 if (get_user(ap->xaccm[0], p))
479 break;
480 err = 0;
481 break;
482
483 case PPPIOCGRASYNCMAP:
484 if (put_user(ap->raccm, p))
485 break;
486 err = 0;
487 break;
488 case PPPIOCSRASYNCMAP:
489 if (get_user(ap->raccm, p))
490 break;
491 err = 0;
492 break;
493
494 case PPPIOCGXASYNCMAP:
495 if (copy_to_user(argp, ap->xaccm, sizeof(ap->xaccm)))
496 break;
497 err = 0;
498 break;
499 case PPPIOCSXASYNCMAP:
500 if (copy_from_user(accm, argp, sizeof(accm)))
501 break;
502 accm[2] &= ~0x40000000U; /* can't escape 0x5e */
503 accm[3] |= 0x60000000U; /* must escape 0x7d, 0x7e */
504 memcpy(ap->xaccm, accm, sizeof(ap->xaccm));
505 err = 0;
506 break;
507
508 case PPPIOCGMRU:
509 if (put_user(ap->mru, (int __user *) argp))
510 break;
511 err = 0;
512 break;
513 case PPPIOCSMRU:
514 if (get_user(val, (int __user *) argp))
515 break;
516 if (val < PPP_MRU)
517 val = PPP_MRU;
518 ap->mru = val;
519 err = 0;
520 break;
521
522 default:
523 err = -ENOTTY;
524 }
525 return err;
526}
527
528/*
529 * This is called at softirq level to deliver received packets
530 * to the ppp_generic code, and to tell the ppp_generic code
531 * if we can accept more output now.
532 */
533static void ppp_sync_process(unsigned long arg)
534{
535 struct syncppp *ap = (struct syncppp *) arg;
536 struct sk_buff *skb;
537
538 /* process received packets */
539 while ((skb = skb_dequeue(&ap->rqueue)) != NULL) {
540 if (skb->len == 0) {
541 /* zero length buffers indicate error */
542 ppp_input_error(&ap->chan, 0);
543 kfree_skb(skb);
544 }
545 else
546 ppp_input(&ap->chan, skb);
547 }
548
549 /* try to push more stuff out */
550 if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_sync_push(ap))
551 ppp_output_wakeup(&ap->chan);
552}
553
554/*
555 * Procedures for encapsulation and framing.
556 */
557
Stephen Hemminger3c582b32008-01-23 20:54:07 -0800558static struct sk_buff*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *skb)
560{
561 int proto;
562 unsigned char *data;
563 int islcp;
564
565 data = skb->data;
566 proto = (data[0] << 8) + data[1];
567
568 /* LCP packets with codes between 1 (configure-request)
569 * and 7 (code-reject) must be sent as though no options
570 * have been negotiated.
571 */
572 islcp = proto == PPP_LCP && 1 <= data[2] && data[2] <= 7;
573
574 /* compress protocol field if option enabled */
575 if (data[0] == 0 && (ap->flags & SC_COMP_PROT) && !islcp)
576 skb_pull(skb,1);
577
578 /* prepend address/control fields if necessary */
579 if ((ap->flags & SC_COMP_AC) == 0 || islcp) {
580 if (skb_headroom(skb) < 2) {
581 struct sk_buff *npkt = dev_alloc_skb(skb->len + 2);
582 if (npkt == NULL) {
583 kfree_skb(skb);
584 return NULL;
585 }
586 skb_reserve(npkt,2);
Arnaldo Carvalho de Melod626f622007-03-27 18:55:52 -0300587 skb_copy_from_linear_data(skb,
588 skb_put(npkt, skb->len), skb->len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589 kfree_skb(skb);
590 skb = npkt;
591 }
592 skb_push(skb,2);
593 skb->data[0] = PPP_ALLSTATIONS;
594 skb->data[1] = PPP_UI;
595 }
596
597 ap->last_xmit = jiffies;
598
599 if (skb && ap->flags & SC_LOG_OUTPKT)
600 ppp_print_buffer ("send buffer", skb->data, skb->len);
601
602 return skb;
603}
604
605/*
606 * Transmit-side routines.
607 */
608
609/*
610 * Send a packet to the peer over an sync tty line.
611 * Returns 1 iff the packet was accepted.
612 * If the packet was not accepted, we will call ppp_output_wakeup
613 * at some later time.
614 */
615static int
616ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb)
617{
618 struct syncppp *ap = chan->private;
619
620 ppp_sync_push(ap);
621
622 if (test_and_set_bit(XMIT_FULL, &ap->xmit_flags))
623 return 0; /* already full */
624 skb = ppp_sync_txmunge(ap, skb);
625 if (skb != NULL)
626 ap->tpkt = skb;
627 else
628 clear_bit(XMIT_FULL, &ap->xmit_flags);
629
630 ppp_sync_push(ap);
631 return 1;
632}
633
634/*
635 * Push as much data as possible out to the tty.
636 */
637static int
638ppp_sync_push(struct syncppp *ap)
639{
640 int sent, done = 0;
641 struct tty_struct *tty = ap->tty;
642 int tty_stuffed = 0;
643
644 if (!spin_trylock_bh(&ap->xmit_lock))
645 return 0;
646 for (;;) {
647 if (test_and_clear_bit(XMIT_WAKEUP, &ap->xmit_flags))
648 tty_stuffed = 0;
Joe Perchescd228d52007-11-12 18:07:31 -0800649 if (!tty_stuffed && ap->tpkt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
Alan Coxf34d7a52008-04-30 00:54:13 -0700651 sent = tty->ops->write(tty, ap->tpkt->data, ap->tpkt->len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652 if (sent < 0)
653 goto flush; /* error, e.g. loss of CD */
654 if (sent < ap->tpkt->len) {
655 tty_stuffed = 1;
656 } else {
657 kfree_skb(ap->tpkt);
658 ap->tpkt = NULL;
659 clear_bit(XMIT_FULL, &ap->xmit_flags);
660 done = 1;
661 }
662 continue;
663 }
664 /* haven't made any progress */
665 spin_unlock_bh(&ap->xmit_lock);
Joe Perches8e95a202009-12-03 07:58:21 +0000666 if (!(test_bit(XMIT_WAKEUP, &ap->xmit_flags) ||
667 (!tty_stuffed && ap->tpkt)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668 break;
669 if (!spin_trylock_bh(&ap->xmit_lock))
670 break;
671 }
672 return done;
673
674flush:
Joe Perchescd228d52007-11-12 18:07:31 -0800675 if (ap->tpkt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676 kfree_skb(ap->tpkt);
677 ap->tpkt = NULL;
678 clear_bit(XMIT_FULL, &ap->xmit_flags);
679 done = 1;
680 }
681 spin_unlock_bh(&ap->xmit_lock);
682 return done;
683}
684
685/*
686 * Flush output from our internal buffers.
687 * Called for the TCFLSH ioctl.
688 */
689static void
690ppp_sync_flush_output(struct syncppp *ap)
691{
692 int done = 0;
693
694 spin_lock_bh(&ap->xmit_lock);
695 if (ap->tpkt != NULL) {
696 kfree_skb(ap->tpkt);
697 ap->tpkt = NULL;
698 clear_bit(XMIT_FULL, &ap->xmit_flags);
699 done = 1;
700 }
701 spin_unlock_bh(&ap->xmit_lock);
702 if (done)
703 ppp_output_wakeup(&ap->chan);
704}
705
706/*
707 * Receive-side routines.
708 */
709
710/* called when the tty driver has data for us.
711 *
712 * Data is frame oriented: each call to ppp_sync_input is considered
713 * a whole frame. If the 1st flag byte is non-zero then the whole
714 * frame is considered to be in error and is tossed.
715 */
716static void
717ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
718 char *flags, int count)
719{
720 struct sk_buff *skb;
721 unsigned char *p;
722
723 if (count == 0)
724 return;
725
726 if (ap->flags & SC_LOG_INPKT)
727 ppp_print_buffer ("receive buffer", buf, count);
728
729 /* stuff the chars in the skb */
Joe Perchescd228d52007-11-12 18:07:31 -0800730 skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2);
731 if (!skb) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732 printk(KERN_ERR "PPPsync: no memory (input pkt)\n");
733 goto err;
734 }
735 /* Try to get the payload 4-byte aligned */
736 if (buf[0] != PPP_ALLSTATIONS)
737 skb_reserve(skb, 2 + (buf[0] & 1));
738
Joe Perchescd228d52007-11-12 18:07:31 -0800739 if (flags && *flags) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 /* error flag set, ignore frame */
741 goto err;
742 } else if (count > skb_tailroom(skb)) {
743 /* packet overflowed MRU */
744 goto err;
745 }
746
747 p = skb_put(skb, count);
748 memcpy(p, buf, count);
749
750 /* strip address/control field if present */
751 p = skb->data;
752 if (p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) {
753 /* chop off address/control */
754 if (skb->len < 3)
755 goto err;
756 p = skb_pull(skb, 2);
757 }
758
759 /* decompress protocol field if compressed */
760 if (p[0] & 1) {
761 /* protocol is compressed */
762 skb_push(skb, 1)[0] = 0;
763 } else if (skb->len < 2)
764 goto err;
765
766 /* queue the frame to be processed */
767 skb_queue_tail(&ap->rqueue, skb);
768 return;
769
770err:
771 /* queue zero length packet as error indication */
772 if (skb || (skb = dev_alloc_skb(0))) {
773 skb_trim(skb, 0);
774 skb_queue_tail(&ap->rqueue, skb);
775 }
776}
777
778static void __exit
779ppp_sync_cleanup(void)
780{
Alexey Dobriyan64ccd712005-06-23 00:10:33 -0700781 if (tty_unregister_ldisc(N_SYNC_PPP) != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782 printk(KERN_ERR "failed to unregister Sync PPP line discipline\n");
783}
784
785module_init(ppp_sync_init);
786module_exit(ppp_sync_cleanup);
787MODULE_LICENSE("GPL");
788MODULE_ALIAS_LDISC(N_SYNC_PPP);