2 * PPP async serial channel driver for Linux.
4 * Copyright 1999 Paul Mackerras.
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.
11 * This driver provides the encapsulation and framing for sending
12 * and receiving PPP frames over async serial lines. It relies on
13 * the generic PPP layer to give it frames to send and to process
14 * received frames. It implements the PPP line discipline.
16 * Part of the code in this driver was inspired by the old async-only
17 * PPP driver, written by Michael Callahan and Al Longyear, and
18 * subsequently hacked by Paul Mackerras.
21 #include <linux/module.h>
22 #include <linux/kernel.h>
23 #include <linux/skbuff.h>
24 #include <linux/tty.h>
25 #include <linux/netdevice.h>
26 #include <linux/poll.h>
27 #include <linux/crc-ccitt.h>
28 #include <linux/ppp_defs.h>
29 #include <linux/if_ppp.h>
30 #include <linux/ppp_channel.h>
31 #include <linux/spinlock.h>
32 #include <linux/init.h>
33 #include <linux/jiffies.h>
34 #include <asm/uaccess.h>
35 #include <asm/string.h>
37 #define PPP_VERSION "2.4.2"
41 /* Structure for storing local state. */
43 struct tty_struct
*tty
;
50 unsigned long xmit_flags
;
53 unsigned int bytes_sent
;
54 unsigned int bytes_rcvd
;
61 unsigned long last_xmit
;
65 struct sk_buff_head rqueue
;
67 struct tasklet_struct tsk
;
70 struct semaphore dead_sem
;
71 struct ppp_channel chan
; /* interface to generic ppp layer */
72 unsigned char obuf
[OBUFSIZE
];
75 /* Bit numbers in xmit_flags */
83 #define SC_PREV_ERROR 4
86 #define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
88 static int flag_time
= HZ
;
89 module_param(flag_time
, int, 0);
90 MODULE_PARM_DESC(flag_time
, "ppp_async: interval between flagged packets (in clock ticks)");
91 MODULE_LICENSE("GPL");
92 MODULE_ALIAS_LDISC(N_PPP
);
97 static int ppp_async_encode(struct asyncppp
*ap
);
98 static int ppp_async_send(struct ppp_channel
*chan
, struct sk_buff
*skb
);
99 static int ppp_async_push(struct asyncppp
*ap
);
100 static void ppp_async_flush_output(struct asyncppp
*ap
);
101 static void ppp_async_input(struct asyncppp
*ap
, const unsigned char *buf
,
102 char *flags
, int count
);
103 static int ppp_async_ioctl(struct ppp_channel
*chan
, unsigned int cmd
,
105 static void ppp_async_process(unsigned long arg
);
107 static void async_lcp_peek(struct asyncppp
*ap
, unsigned char *data
,
108 int len
, int inbound
);
110 static struct ppp_channel_ops async_ops
= {
116 * Routines implementing the PPP line discipline.
120 * We have a potential race on dereferencing tty->disc_data,
121 * because the tty layer provides no locking at all - thus one
122 * cpu could be running ppp_asynctty_receive while another
123 * calls ppp_asynctty_close, which zeroes tty->disc_data and
124 * frees the memory that ppp_asynctty_receive is using. The best
125 * way to fix this is to use a rwlock in the tty struct, but for now
126 * we use a single global rwlock for all ttys in ppp line discipline.
128 * FIXME: this is no longer true. The _close path for the ldisc is
129 * now guaranteed to be sane.
131 static DEFINE_RWLOCK(disc_data_lock
);
133 static struct asyncppp
*ap_get(struct tty_struct
*tty
)
137 read_lock(&disc_data_lock
);
140 atomic_inc(&ap
->refcnt
);
141 read_unlock(&disc_data_lock
);
145 static void ap_put(struct asyncppp
*ap
)
147 if (atomic_dec_and_test(&ap
->refcnt
))
152 * Called when a tty is put into PPP line discipline. Called in process
156 ppp_asynctty_open(struct tty_struct
*tty
)
161 if (tty
->ops
->write
== NULL
)
165 ap
= kzalloc(sizeof(*ap
), GFP_KERNEL
);
169 /* initialize the asyncppp structure */
172 spin_lock_init(&ap
->xmit_lock
);
173 spin_lock_init(&ap
->recv_lock
);
175 ap
->xaccm
[3] = 0x60000000U
;
181 skb_queue_head_init(&ap
->rqueue
);
182 tasklet_init(&ap
->tsk
, ppp_async_process
, (unsigned long) ap
);
184 atomic_set(&ap
->refcnt
, 1);
185 init_MUTEX_LOCKED(&ap
->dead_sem
);
187 ap
->chan
.private = ap
;
188 ap
->chan
.ops
= &async_ops
;
189 ap
->chan
.mtu
= PPP_MRU
;
190 err
= ppp_register_channel(&ap
->chan
);
195 tty
->receive_room
= 65536;
205 * Called when the tty is put into another line discipline
206 * or it hangs up. We have to wait for any cpu currently
207 * executing in any of the other ppp_asynctty_* routines to
208 * finish before we can call ppp_unregister_channel and free
209 * the asyncppp struct. This routine must be called from
210 * process context, not interrupt or softirq context.
213 ppp_asynctty_close(struct tty_struct
*tty
)
217 write_lock_irq(&disc_data_lock
);
219 tty
->disc_data
= NULL
;
220 write_unlock_irq(&disc_data_lock
);
225 * We have now ensured that nobody can start using ap from now
226 * on, but we have to wait for all existing users to finish.
227 * Note that ppp_unregister_channel ensures that no calls to
228 * our channel ops (i.e. ppp_async_send/ioctl) are in progress
229 * by the time it returns.
231 if (!atomic_dec_and_test(&ap
->refcnt
))
233 tasklet_kill(&ap
->tsk
);
235 ppp_unregister_channel(&ap
->chan
);
238 skb_queue_purge(&ap
->rqueue
);
245 * Called on tty hangup in process context.
247 * Wait for I/O to driver to complete and unregister PPP channel.
248 * This is already done by the close routine, so just call that.
250 static int ppp_asynctty_hangup(struct tty_struct
*tty
)
252 ppp_asynctty_close(tty
);
257 * Read does nothing - no data is ever available this way.
258 * Pppd reads and writes packets via /dev/ppp instead.
261 ppp_asynctty_read(struct tty_struct
*tty
, struct file
*file
,
262 unsigned char __user
*buf
, size_t count
)
268 * Write on the tty does nothing, the packets all come in
269 * from the ppp generic stuff.
272 ppp_asynctty_write(struct tty_struct
*tty
, struct file
*file
,
273 const unsigned char *buf
, size_t count
)
279 * Called in process context only. May be re-entered by multiple
280 * ioctl calling threads.
284 ppp_asynctty_ioctl(struct tty_struct
*tty
, struct file
*file
,
285 unsigned int cmd
, unsigned long arg
)
287 struct asyncppp
*ap
= ap_get(tty
);
289 int __user
*p
= (int __user
*)arg
;
300 if (put_user(ppp_channel_index(&ap
->chan
), p
))
310 if (put_user(ppp_unit_number(&ap
->chan
), p
))
316 /* flush our buffers and the serial port's buffer */
317 if (arg
== TCIOFLUSH
|| arg
== TCOFLUSH
)
318 ppp_async_flush_output(ap
);
319 err
= tty_perform_flush(tty
, arg
);
324 if (put_user(val
, p
))
330 /* Try the various mode ioctls */
331 err
= tty_mode_ioctl(tty
, file
, cmd
, arg
);
338 /* No kernel lock - fine */
340 ppp_asynctty_poll(struct tty_struct
*tty
, struct file
*file
, poll_table
*wait
)
346 * This can now be called from hard interrupt level as well
347 * as soft interrupt level or mainline.
350 ppp_asynctty_receive(struct tty_struct
*tty
, const unsigned char *buf
,
351 char *cflags
, int count
)
353 struct asyncppp
*ap
= ap_get(tty
);
358 spin_lock_irqsave(&ap
->recv_lock
, flags
);
359 ppp_async_input(ap
, buf
, cflags
, count
);
360 spin_unlock_irqrestore(&ap
->recv_lock
, flags
);
361 if (!skb_queue_empty(&ap
->rqueue
))
362 tasklet_schedule(&ap
->tsk
);
364 if (test_and_clear_bit(TTY_THROTTLED
, &tty
->flags
)
365 && tty
->ops
->unthrottle
)
366 tty
->ops
->unthrottle(tty
);
370 ppp_asynctty_wakeup(struct tty_struct
*tty
)
372 struct asyncppp
*ap
= ap_get(tty
);
374 clear_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
377 set_bit(XMIT_WAKEUP
, &ap
->xmit_flags
);
378 tasklet_schedule(&ap
->tsk
);
383 static struct tty_ldisc ppp_ldisc
= {
384 .owner
= THIS_MODULE
,
385 .magic
= TTY_LDISC_MAGIC
,
387 .open
= ppp_asynctty_open
,
388 .close
= ppp_asynctty_close
,
389 .hangup
= ppp_asynctty_hangup
,
390 .read
= ppp_asynctty_read
,
391 .write
= ppp_asynctty_write
,
392 .ioctl
= ppp_asynctty_ioctl
,
393 .poll
= ppp_asynctty_poll
,
394 .receive_buf
= ppp_asynctty_receive
,
395 .write_wakeup
= ppp_asynctty_wakeup
,
403 err
= tty_register_ldisc(N_PPP
, &ppp_ldisc
);
405 printk(KERN_ERR
"PPP_async: error %d registering line disc.\n",
411 * The following routines provide the PPP channel interface.
414 ppp_async_ioctl(struct ppp_channel
*chan
, unsigned int cmd
, unsigned long arg
)
416 struct asyncppp
*ap
= chan
->private;
417 void __user
*argp
= (void __user
*)arg
;
418 int __user
*p
= argp
;
425 val
= ap
->flags
| ap
->rbits
;
426 if (put_user(val
, p
))
431 if (get_user(val
, p
))
433 ap
->flags
= val
& ~SC_RCV_BITS
;
434 spin_lock_irq(&ap
->recv_lock
);
435 ap
->rbits
= val
& SC_RCV_BITS
;
436 spin_unlock_irq(&ap
->recv_lock
);
440 case PPPIOCGASYNCMAP
:
441 if (put_user(ap
->xaccm
[0], (u32 __user
*)argp
))
445 case PPPIOCSASYNCMAP
:
446 if (get_user(ap
->xaccm
[0], (u32 __user
*)argp
))
451 case PPPIOCGRASYNCMAP
:
452 if (put_user(ap
->raccm
, (u32 __user
*)argp
))
456 case PPPIOCSRASYNCMAP
:
457 if (get_user(ap
->raccm
, (u32 __user
*)argp
))
462 case PPPIOCGXASYNCMAP
:
463 if (copy_to_user(argp
, ap
->xaccm
, sizeof(ap
->xaccm
)))
467 case PPPIOCSXASYNCMAP
:
468 if (copy_from_user(accm
, argp
, sizeof(accm
)))
470 accm
[2] &= ~0x40000000U
; /* can't escape 0x5e */
471 accm
[3] |= 0x60000000U
; /* must escape 0x7d, 0x7e */
472 memcpy(ap
->xaccm
, accm
, sizeof(ap
->xaccm
));
477 if (put_user(ap
->mru
, p
))
482 if (get_user(val
, p
))
498 * This is called at softirq level to deliver received packets
499 * to the ppp_generic code, and to tell the ppp_generic code
500 * if we can accept more output now.
502 static void ppp_async_process(unsigned long arg
)
504 struct asyncppp
*ap
= (struct asyncppp
*) arg
;
507 /* process received packets */
508 while ((skb
= skb_dequeue(&ap
->rqueue
)) != NULL
) {
510 ppp_input_error(&ap
->chan
, 0);
511 ppp_input(&ap
->chan
, skb
);
514 /* try to push more stuff out */
515 if (test_bit(XMIT_WAKEUP
, &ap
->xmit_flags
) && ppp_async_push(ap
))
516 ppp_output_wakeup(&ap
->chan
);
520 * Procedures for encapsulation and framing.
524 * Procedure to encode the data for async serial transmission.
525 * Does octet stuffing (escaping), puts the address/control bytes
526 * on if A/C compression is disabled, and does protocol compression.
527 * Assumes ap->tpkt != 0 on entry.
528 * Returns 1 if we finished the current frame, 0 otherwise.
531 #define PUT_BYTE(ap, buf, c, islcp) do { \
532 if ((islcp && c < 0x20) || (ap->xaccm[c >> 5] & (1 << (c & 0x1f)))) {\
533 *buf++ = PPP_ESCAPE; \
540 ppp_async_encode(struct asyncppp
*ap
)
542 int fcs
, i
, count
, c
, proto
;
543 unsigned char *buf
, *buflim
;
551 data
= ap
->tpkt
->data
;
552 count
= ap
->tpkt
->len
;
554 proto
= (data
[0] << 8) + data
[1];
557 * LCP packets with code values between 1 (configure-reqest)
558 * and 7 (code-reject) must be sent as though no options
559 * had been negotiated.
561 islcp
= proto
== PPP_LCP
&& 1 <= data
[2] && data
[2] <= 7;
565 async_lcp_peek(ap
, data
, count
, 0);
568 * Start of a new packet - insert the leading FLAG
569 * character if necessary.
571 if (islcp
|| flag_time
== 0
572 || time_after_eq(jiffies
, ap
->last_xmit
+ flag_time
))
574 ap
->last_xmit
= jiffies
;
578 * Put in the address/control bytes if necessary
580 if ((ap
->flags
& SC_COMP_AC
) == 0 || islcp
) {
581 PUT_BYTE(ap
, buf
, 0xff, islcp
);
582 fcs
= PPP_FCS(fcs
, 0xff);
583 PUT_BYTE(ap
, buf
, 0x03, islcp
);
584 fcs
= PPP_FCS(fcs
, 0x03);
589 * Once we put in the last byte, we need to put in the FCS
590 * and closing flag, so make sure there is at least 7 bytes
591 * of free space in the output buffer.
593 buflim
= ap
->obuf
+ OBUFSIZE
- 6;
594 while (i
< count
&& buf
< buflim
) {
596 if (i
== 1 && c
== 0 && (ap
->flags
& SC_COMP_PROT
))
597 continue; /* compress protocol field */
598 fcs
= PPP_FCS(fcs
, c
);
599 PUT_BYTE(ap
, buf
, c
, islcp
);
604 * Remember where we are up to in this packet.
613 * We have finished the packet. Add the FCS and flag.
617 PUT_BYTE(ap
, buf
, c
, islcp
);
618 c
= (fcs
>> 8) & 0xff;
619 PUT_BYTE(ap
, buf
, c
, islcp
);
629 * Transmit-side routines.
633 * Send a packet to the peer over an async tty line.
634 * Returns 1 iff the packet was accepted.
635 * If the packet was not accepted, we will call ppp_output_wakeup
636 * at some later time.
639 ppp_async_send(struct ppp_channel
*chan
, struct sk_buff
*skb
)
641 struct asyncppp
*ap
= chan
->private;
645 if (test_and_set_bit(XMIT_FULL
, &ap
->xmit_flags
))
646 return 0; /* already full */
655 * Push as much data as possible out to the tty.
658 ppp_async_push(struct asyncppp
*ap
)
660 int avail
, sent
, done
= 0;
661 struct tty_struct
*tty
= ap
->tty
;
665 * We can get called recursively here if the tty write
666 * function calls our wakeup function. This can happen
667 * for example on a pty with both the master and slave
668 * set to PPP line discipline.
669 * We use the XMIT_BUSY bit to detect this and get out,
670 * leaving the XMIT_WAKEUP bit set to tell the other
671 * instance that it may now be able to write more now.
673 if (test_and_set_bit(XMIT_BUSY
, &ap
->xmit_flags
))
675 spin_lock_bh(&ap
->xmit_lock
);
677 if (test_and_clear_bit(XMIT_WAKEUP
, &ap
->xmit_flags
))
679 if (!tty_stuffed
&& ap
->optr
< ap
->olim
) {
680 avail
= ap
->olim
- ap
->optr
;
681 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
682 sent
= tty
->ops
->write(tty
, ap
->optr
, avail
);
684 goto flush
; /* error, e.g. loss of CD */
690 if (ap
->optr
>= ap
->olim
&& ap
->tpkt
) {
691 if (ppp_async_encode(ap
)) {
692 /* finished processing ap->tpkt */
693 clear_bit(XMIT_FULL
, &ap
->xmit_flags
);
699 * We haven't made any progress this time around.
700 * Clear XMIT_BUSY to let other callers in, but
701 * after doing so we have to check if anyone set
702 * XMIT_WAKEUP since we last checked it. If they
703 * did, we should try again to set XMIT_BUSY and go
704 * around again in case XMIT_BUSY was still set when
705 * the other caller tried.
707 clear_bit(XMIT_BUSY
, &ap
->xmit_flags
);
708 /* any more work to do? if not, exit the loop */
709 if (!(test_bit(XMIT_WAKEUP
, &ap
->xmit_flags
)
710 || (!tty_stuffed
&& ap
->tpkt
)))
712 /* more work to do, see if we can do it now */
713 if (test_and_set_bit(XMIT_BUSY
, &ap
->xmit_flags
))
716 spin_unlock_bh(&ap
->xmit_lock
);
720 clear_bit(XMIT_BUSY
, &ap
->xmit_flags
);
724 clear_bit(XMIT_FULL
, &ap
->xmit_flags
);
728 spin_unlock_bh(&ap
->xmit_lock
);
733 * Flush output from our internal buffers.
734 * Called for the TCFLSH ioctl. Can be entered in parallel
735 * but this is covered by the xmit_lock.
738 ppp_async_flush_output(struct asyncppp
*ap
)
742 spin_lock_bh(&ap
->xmit_lock
);
744 if (ap
->tpkt
!= NULL
) {
747 clear_bit(XMIT_FULL
, &ap
->xmit_flags
);
750 spin_unlock_bh(&ap
->xmit_lock
);
752 ppp_output_wakeup(&ap
->chan
);
756 * Receive-side routines.
759 /* see how many ordinary chars there are at the start of buf */
761 scan_ordinary(struct asyncppp
*ap
, const unsigned char *buf
, int count
)
765 for (i
= 0; i
< count
; ++i
) {
767 if (c
== PPP_ESCAPE
|| c
== PPP_FLAG
768 || (c
< 0x20 && (ap
->raccm
& (1 << c
)) != 0))
774 /* called when a flag is seen - do end-of-packet processing */
776 process_input_packet(struct asyncppp
*ap
)
780 unsigned int len
, fcs
, proto
;
783 if (ap
->state
& (SC_TOSS
| SC_ESCAPE
))
787 return; /* 0-length packet */
793 goto err
; /* too short */
795 for (; len
> 0; --len
)
796 fcs
= PPP_FCS(fcs
, *p
++);
797 if (fcs
!= PPP_GOODFCS
)
798 goto err
; /* bad FCS */
799 skb_trim(skb
, skb
->len
- 2);
801 /* check for address/control and protocol compression */
803 if (p
[0] == PPP_ALLSTATIONS
) {
804 /* chop off address/control */
805 if (p
[1] != PPP_UI
|| skb
->len
< 3)
807 p
= skb_pull(skb
, 2);
811 /* protocol is compressed */
812 skb_push(skb
, 1)[0] = 0;
816 proto
= (proto
<< 8) + p
[1];
817 if (proto
== PPP_LCP
)
818 async_lcp_peek(ap
, p
, skb
->len
, 1);
821 /* queue the frame to be processed */
822 skb
->cb
[0] = ap
->state
;
823 skb_queue_tail(&ap
->rqueue
, skb
);
829 /* frame had an error, remember that, reset SC_TOSS & SC_ESCAPE */
830 ap
->state
= SC_PREV_ERROR
;
832 /* make skb appear as freshly allocated */
834 skb_reserve(skb
, - skb_headroom(skb
));
838 /* Called when the tty driver has data for us. Runs parallel with the
839 other ldisc functions but will not be re-entered */
842 ppp_async_input(struct asyncppp
*ap
, const unsigned char *buf
,
843 char *flags
, int count
)
846 int c
, i
, j
, n
, s
, f
;
849 /* update bits used for 8-bit cleanness detection */
850 if (~ap
->rbits
& SC_RCV_BITS
) {
852 for (i
= 0; i
< count
; ++i
) {
854 if (flags
&& flags
[i
] != 0)
856 s
|= (c
& 0x80)? SC_RCV_B7_1
: SC_RCV_B7_0
;
857 c
= ((c
>> 4) ^ c
) & 0xf;
858 s
|= (0x6996 & (1 << c
))? SC_RCV_ODDP
: SC_RCV_EVNP
;
864 /* scan through and see how many chars we can do in bulk */
865 if ((ap
->state
& SC_ESCAPE
) && buf
[0] == PPP_ESCAPE
)
868 n
= scan_ordinary(ap
, buf
, count
);
871 if (flags
&& (ap
->state
& SC_TOSS
) == 0) {
872 /* check the flags to see if any char had an error */
873 for (j
= 0; j
< n
; ++j
)
874 if ((f
= flags
[j
]) != 0)
879 ap
->state
|= SC_TOSS
;
881 } else if (n
> 0 && (ap
->state
& SC_TOSS
) == 0) {
882 /* stuff the chars in the skb */
885 skb
= dev_alloc_skb(ap
->mru
+ PPP_HDRLEN
+ 2);
891 /* Try to get the payload 4-byte aligned.
892 * This should match the
893 * PPP_ALLSTATIONS/PPP_UI/compressed tests in
894 * process_input_packet, but we do not have
895 * enough chars here to test buf[1] and buf[2].
897 if (buf
[0] != PPP_ALLSTATIONS
)
898 skb_reserve(skb
, 2 + (buf
[0] & 1));
900 if (n
> skb_tailroom(skb
)) {
901 /* packet overflowed MRU */
902 ap
->state
|= SC_TOSS
;
904 sp
= skb_put(skb
, n
);
906 if (ap
->state
& SC_ESCAPE
) {
908 ap
->state
&= ~SC_ESCAPE
;
917 if (flags
!= NULL
&& flags
[n
] != 0) {
918 ap
->state
|= SC_TOSS
;
919 } else if (c
== PPP_FLAG
) {
920 process_input_packet(ap
);
921 } else if (c
== PPP_ESCAPE
) {
922 ap
->state
|= SC_ESCAPE
;
923 } else if (I_IXON(ap
->tty
)) {
924 if (c
== START_CHAR(ap
->tty
))
926 else if (c
== STOP_CHAR(ap
->tty
))
929 /* otherwise it's a char in the recv ACCM */
940 printk(KERN_ERR
"PPPasync: no memory (input pkt)\n");
941 ap
->state
|= SC_TOSS
;
945 * We look at LCP frames going past so that we can notice
946 * and react to the LCP configure-ack from the peer.
947 * In the situation where the peer has been sent a configure-ack
948 * already, LCP is up once it has sent its configure-ack
949 * so the immediately following packet can be sent with the
950 * configured LCP options. This allows us to process the following
951 * packet correctly without pppd needing to respond quickly.
953 * We only respond to the received configure-ack if we have just
954 * sent a configure-request, and the configure-ack contains the
955 * same data (this is checked using a 16-bit crc of the data).
957 #define CONFREQ 1 /* LCP code field values */
959 #define LCP_MRU 1 /* LCP option numbers */
960 #define LCP_ASYNCMAP 2
962 static void async_lcp_peek(struct asyncppp
*ap
, unsigned char *data
,
963 int len
, int inbound
)
965 int dlen
, fcs
, i
, code
;
968 data
+= 2; /* skip protocol bytes */
970 if (len
< 4) /* 4 = code, ID, length */
973 if (code
!= CONFACK
&& code
!= CONFREQ
)
975 dlen
= (data
[2] << 8) + data
[3];
977 return; /* packet got truncated or length is bogus */
979 if (code
== (inbound
? CONFACK
: CONFREQ
)) {
981 * sent confreq or received confack:
982 * calculate the crc of the data from the ID field on.
985 for (i
= 1; i
< dlen
; ++i
)
986 fcs
= PPP_FCS(fcs
, data
[i
]);
989 /* outbound confreq - remember the crc for later */
994 /* received confack, check the crc */
1000 return; /* not interested in received confreq */
1002 /* process the options in the confack */
1005 /* data[0] is code, data[1] is length */
1006 while (dlen
>= 2 && dlen
>= data
[1] && data
[1] >= 2) {
1009 val
= (data
[2] << 8) + data
[3];
1016 val
= (data
[2] << 24) + (data
[3] << 16)
1017 + (data
[4] << 8) + data
[5];
1029 static void __exit
ppp_async_cleanup(void)
1031 if (tty_unregister_ldisc(N_PPP
) != 0)
1032 printk(KERN_ERR
"failed to unregister PPP line discipline\n");
1035 module_init(ppp_async_init
);
1036 module_exit(ppp_async_cleanup
);