Orange Pi5 kernel

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * PPP async serial channel driver for Linux.
 *
 * Copyright 1999 Paul Mackerras.
 *
 * This driver provides the encapsulation and framing for sending
 * and receiving PPP frames over async serial lines.  It relies on
 * the generic PPP layer to give it frames to send and to process
 * received frames.  It implements the PPP line discipline.
 *
 * Part of the code in this driver was inspired by the old async-only
 * PPP driver, written by Michael Callahan and Al Longyear, and
 * subsequently hacked by Paul Mackerras.
 */
 
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/tty.h>
#include <linux/netdevice.h>
#include <linux/poll.h>
#include <linux/crc-ccitt.h>
#include <linux/ppp_defs.h>
#include <linux/ppp-ioctl.h>
#include <linux/ppp_channel.h>
#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/slab.h>
#include <asm/unaligned.h>
#include <linux/uaccess.h>
#include <asm/string.h>
 
#define PPP_VERSION	"2.4.2"
 
#define OBUFSIZE	4096
 
/* Structure for storing local state. */
struct asyncppp {
<------>struct tty_struct *tty;
<------>unsigned int	flags;
<------>unsigned int	state;
<------>unsigned int	rbits;
<------>int		mru;
<------>spinlock_t	xmit_lock;
<------>spinlock_t	recv_lock;
<------>unsigned long	xmit_flags;
<------>u32		xaccm[8];
<------>u32		raccm;
<------>unsigned int	bytes_sent;
<------>unsigned int	bytes_rcvd;
 
<------>struct sk_buff	*tpkt;
<------>int		tpkt_pos;
<------>u16		tfcs;
<------>unsigned char	*optr;
<------>unsigned char	*olim;
<------>unsigned long	last_xmit;
 
<------>struct sk_buff	*rpkt;
<------>int		lcp_fcs;
<------>struct sk_buff_head rqueue;
 
<------>struct tasklet_struct tsk;
 
<------>refcount_t	refcnt;
<------>struct completion dead;
<------>struct ppp_channel chan;	/* interface to generic ppp layer */
<------>unsigned char	obuf[OBUFSIZE];
};
 
/* Bit numbers in xmit_flags */
#define XMIT_WAKEUP	0
#define XMIT_FULL	1
#define XMIT_BUSY	2
 
/* State bits */
#define SC_TOSS		1
#define SC_ESCAPE	2
#define SC_PREV_ERROR	4
 
/* Bits in rbits */
#define SC_RCV_BITS	(SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
 
static int flag_time = HZ;
module_param(flag_time, int, 0);
MODULE_PARM_DESC(flag_time, "ppp_async: interval between flagged packets (in clock ticks)");
MODULE_LICENSE("GPL");
MODULE_ALIAS_LDISC(N_PPP);
 
/*
 * Prototypes.
 */
static int ppp_async_encode(struct asyncppp *ap);
static int ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb);
static int ppp_async_push(struct asyncppp *ap);
static void ppp_async_flush_output(struct asyncppp *ap);
static void ppp_async_input(struct asyncppp *ap, const unsigned char *buf,
<------><------><------>    char *flags, int count);
static int ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd,
<------><------><------>   unsigned long arg);
static void ppp_async_process(unsigned long arg);
 
static void async_lcp_peek(struct asyncppp *ap, unsigned char *data,
<------><------><------>   int len, int inbound);
 
static const struct ppp_channel_ops async_ops = {
<------>.start_xmit = ppp_async_send,
<------>.ioctl      = ppp_async_ioctl,
};
 
/*
 * Routines implementing the PPP line discipline.
 */
 
/*
 * We have a potential race on dereferencing tty->disc_data,
 * because the tty layer provides no locking at all - thus one
 * cpu could be running ppp_asynctty_receive while another
 * calls ppp_asynctty_close, which zeroes tty->disc_data and
 * frees the memory that ppp_asynctty_receive is using.  The best
 * way to fix this is to use a rwlock in the tty struct, but for now
 * we use a single global rwlock for all ttys in ppp line discipline.
 *
 * FIXME: this is no longer true. The _close path for the ldisc is
 * now guaranteed to be sane.
 */
static DEFINE_RWLOCK(disc_data_lock);
 
static struct asyncppp *ap_get(struct tty_struct *tty)
{
<------>struct asyncppp *ap;
 
<------>read_lock(&disc_data_lock);
<------>ap = tty->disc_data;
<------>if (ap != NULL)
<------><------>refcount_inc(&ap->refcnt);
<------>read_unlock(&disc_data_lock);
<------>return ap;
}
 
static void ap_put(struct asyncppp *ap)
{
<------>if (refcount_dec_and_test(&ap->refcnt))
<------><------>complete(&ap->dead);
}
 
/*
 * Called when a tty is put into PPP line discipline. Called in process
 * context.
 */
static int
ppp_asynctty_open(struct tty_struct *tty)
{
<------>struct asyncppp *ap;
<------>int err;
<------>int speed;
 
<------>if (tty->ops->write == NULL)
<------><------>return -EOPNOTSUPP;
 
<------>err = -ENOMEM;
<------>ap = kzalloc(sizeof(*ap), GFP_KERNEL);
<------>if (!ap)
<------><------>goto out;
 
<------>/* initialize the asyncppp structure */
<------>ap->tty = tty;
<------>ap->mru = PPP_MRU;
<------>spin_lock_init(&ap->xmit_lock);
<------>spin_lock_init(&ap->recv_lock);
<------>ap->xaccm[0] = ~0U;
<------>ap->xaccm[3] = 0x60000000U;
<------>ap->raccm = ~0U;
<------>ap->optr = ap->obuf;
<------>ap->olim = ap->obuf;
<------>ap->lcp_fcs = -1;
 
<------>skb_queue_head_init(&ap->rqueue);
<------>tasklet_init(&ap->tsk, ppp_async_process, (unsigned long) ap);
 
<------>refcount_set(&ap->refcnt, 1);
<------>init_completion(&ap->dead);
 
<------>ap->chan.private = ap;
<------>ap->chan.ops = &async_ops;
<------>ap->chan.mtu = PPP_MRU;
<------>speed = tty_get_baud_rate(tty);
<------>ap->chan.speed = speed;
<------>err = ppp_register_channel(&ap->chan);
<------>if (err)
<------><------>goto out_free;
 
<------>tty->disc_data = ap;
<------>tty->receive_room = 65536;
<------>return 0;
 
 out_free:
<------>kfree(ap);
 out:
<------>return err;
}
 
/*
 * Called when the tty is put into another line discipline
 * or it hangs up.  We have to wait for any cpu currently
 * executing in any of the other ppp_asynctty_* routines to
 * finish before we can call ppp_unregister_channel and free
 * the asyncppp struct.  This routine must be called from
 * process context, not interrupt or softirq context.
 */
static void
ppp_asynctty_close(struct tty_struct *tty)
{
<------>struct asyncppp *ap;
 
<------>write_lock_irq(&disc_data_lock);
<------>ap = tty->disc_data;
<------>tty->disc_data = NULL;
<------>write_unlock_irq(&disc_data_lock);
<------>if (!ap)
<------><------>return;
 
<------>/*
<------> * We have now ensured that nobody can start using ap from now
<------> * on, but we have to wait for all existing users to finish.
<------> * Note that ppp_unregister_channel ensures that no calls to
<------> * our channel ops (i.e. ppp_async_send/ioctl) are in progress
<------> * by the time it returns.
<------> */
<------>if (!refcount_dec_and_test(&ap->refcnt))
<------><------>wait_for_completion(&ap->dead);
<------>tasklet_kill(&ap->tsk);
 
<------>ppp_unregister_channel(&ap->chan);
<------>kfree_skb(ap->rpkt);
<------>skb_queue_purge(&ap->rqueue);
<------>kfree_skb(ap->tpkt);
<------>kfree(ap);
}
 
/*
 * Called on tty hangup in process context.
 *
 * Wait for I/O to driver to complete and unregister PPP channel.
 * This is already done by the close routine, so just call that.
 */
static int ppp_asynctty_hangup(struct tty_struct *tty)
{
<------>ppp_asynctty_close(tty);
<------>return 0;
}
 
/*
 * Read does nothing - no data is ever available this way.
 * Pppd reads and writes packets via /dev/ppp instead.
 */
static ssize_t
ppp_asynctty_read(struct tty_struct *tty, struct file *file,
<------><------>  unsigned char *buf, size_t count,
<------><------>  void **cookie, unsigned long offset)
{
<------>return -EAGAIN;
}
 
/*
 * Write on the tty does nothing, the packets all come in
 * from the ppp generic stuff.
 */
static ssize_t
ppp_asynctty_write(struct tty_struct *tty, struct file *file,
<------><------>   const unsigned char *buf, size_t count)
{
<------>return -EAGAIN;
}
 
/*
 * Called in process context only. May be re-entered by multiple
 * ioctl calling threads.
 */
 
static int
ppp_asynctty_ioctl(struct tty_struct *tty, struct file *file,
<------><------>   unsigned int cmd, unsigned long arg)
{
<------>struct asyncppp *ap = ap_get(tty);
<------>int err, val;
<------>int __user *p = (int __user *)arg;
 
<------>if (!ap)
<------><------>return -ENXIO;
<------>err = -EFAULT;
<------>switch (cmd) {
<------>case PPPIOCGCHAN:
<------><------>err = -EFAULT;
<------><------>if (put_user(ppp_channel_index(&ap->chan), p))
<------><------><------>break;
<------><------>err = 0;
<------><------>break;
 
<------>case PPPIOCGUNIT:
<------><------>err = -EFAULT;
<------><------>if (put_user(ppp_unit_number(&ap->chan), p))
<------><------><------>break;
<------><------>err = 0;
<------><------>break;
 
<------>case TCFLSH:
<------><------>/* flush our buffers and the serial port's buffer */
<------><------>if (arg == TCIOFLUSH || arg == TCOFLUSH)
<------><------><------>ppp_async_flush_output(ap);
<------><------>err = n_tty_ioctl_helper(tty, file, cmd, arg);
<------><------>break;
 
<------>case FIONREAD:
<------><------>val = 0;
<------><------>if (put_user(val, p))
<------><------><------>break;
<------><------>err = 0;
<------><------>break;
 
<------>default:
<------><------>/* Try the various mode ioctls */
<------><------>err = tty_mode_ioctl(tty, file, cmd, arg);
<------>}
 
<------>ap_put(ap);
<------>return err;
}
 
/* No kernel lock - fine */
static __poll_t
ppp_asynctty_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
{
<------>return 0;
}
 
/* May sleep, don't call from interrupt level or with interrupts disabled */
static void
ppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf,
<------><------>  char *cflags, int count)
{
<------>struct asyncppp *ap = ap_get(tty);
<------>unsigned long flags;
 
<------>if (!ap)
<------><------>return;
<------>spin_lock_irqsave(&ap->recv_lock, flags);
<------>ppp_async_input(ap, buf, cflags, count);
<------>spin_unlock_irqrestore(&ap->recv_lock, flags);
<------>if (!skb_queue_empty(&ap->rqueue))
<------><------>tasklet_schedule(&ap->tsk);
<------>ap_put(ap);
<------>tty_unthrottle(tty);
}
 
static void
ppp_asynctty_wakeup(struct tty_struct *tty)
{
<------>struct asyncppp *ap = ap_get(tty);
 
<------>clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
<------>if (!ap)
<------><------>return;
<------>set_bit(XMIT_WAKEUP, &ap->xmit_flags);
<------>tasklet_schedule(&ap->tsk);
<------>ap_put(ap);
}
 
 
static struct tty_ldisc_ops ppp_ldisc = {
<------>.owner  = THIS_MODULE,
<------>.magic	= TTY_LDISC_MAGIC,
<------>.name	= "ppp",
<------>.open	= ppp_asynctty_open,
<------>.close	= ppp_asynctty_close,
<------>.hangup	= ppp_asynctty_hangup,
<------>.read	= ppp_asynctty_read,
<------>.write	= ppp_asynctty_write,
<------>.ioctl	= ppp_asynctty_ioctl,
<------>.poll	= ppp_asynctty_poll,
<------>.receive_buf = ppp_asynctty_receive,
<------>.write_wakeup = ppp_asynctty_wakeup,
};
 
static int __init
ppp_async_init(void)
{
<------>int err;
 
<------>err = tty_register_ldisc(N_PPP, &ppp_ldisc);
<------>if (err != 0)
<------><------>printk(KERN_ERR "PPP_async: error %d registering line disc.\n",
<------><------>       err);
<------>return err;
}
 
/*
 * The following routines provide the PPP channel interface.
 */
static int
ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg)
{
<------>struct asyncppp *ap = chan->private;
<------>void __user *argp = (void __user *)arg;
<------>int __user *p = argp;
<------>int err, val;
<------>u32 accm[8];
 
<------>err = -EFAULT;
<------>switch (cmd) {
<------>case PPPIOCGFLAGS:
<------><------>val = ap->flags | ap->rbits;
<------><------>if (put_user(val, p))
<------><------><------>break;
<------><------>err = 0;
<------><------>break;
<------>case PPPIOCSFLAGS:
<------><------>if (get_user(val, p))
<------><------><------>break;
<------><------>ap->flags = val & ~SC_RCV_BITS;
<------><------>spin_lock_irq(&ap->recv_lock);
<------><------>ap->rbits = val & SC_RCV_BITS;
<------><------>spin_unlock_irq(&ap->recv_lock);
<------><------>err = 0;
<------><------>break;
 
<------>case PPPIOCGASYNCMAP:
<------><------>if (put_user(ap->xaccm[0], (u32 __user *)argp))
<------><------><------>break;
<------><------>err = 0;
<------><------>break;
<------>case PPPIOCSASYNCMAP:
<------><------>if (get_user(ap->xaccm[0], (u32 __user *)argp))
<------><------><------>break;
<------><------>err = 0;
<------><------>break;
 
<------>case PPPIOCGRASYNCMAP:
<------><------>if (put_user(ap->raccm, (u32 __user *)argp))
<------><------><------>break;
<------><------>err = 0;
<------><------>break;
<------>case PPPIOCSRASYNCMAP:
<------><------>if (get_user(ap->raccm, (u32 __user *)argp))
<------><------><------>break;
<------><------>err = 0;
<------><------>break;
 
<------>case PPPIOCGXASYNCMAP:
<------><------>if (copy_to_user(argp, ap->xaccm, sizeof(ap->xaccm)))
<------><------><------>break;
<------><------>err = 0;
<------><------>break;
<------>case PPPIOCSXASYNCMAP:
<------><------>if (copy_from_user(accm, argp, sizeof(accm)))
<------><------><------>break;
<------><------>accm[2] &= ~0x40000000U;	/* can't escape 0x5e */
<------><------>accm[3] |= 0x60000000U;		/* must escape 0x7d, 0x7e */
<------><------>memcpy(ap->xaccm, accm, sizeof(ap->xaccm));
<------><------>err = 0;
<------><------>break;
 
<------>case PPPIOCGMRU:
<------><------>if (put_user(ap->mru, p))
<------><------><------>break;
<------><------>err = 0;
<------><------>break;
<------>case PPPIOCSMRU:
<------><------>if (get_user(val, p))
<------><------><------>break;
<------><------>if (val < PPP_MRU)
<------><------><------>val = PPP_MRU;
<------><------>ap->mru = val;
<------><------>err = 0;
<------><------>break;
 
<------>default:
<------><------>err = -ENOTTY;
<------>}
 
<------>return err;
}
 
/*
 * This is called at softirq level to deliver received packets
 * to the ppp_generic code, and to tell the ppp_generic code
 * if we can accept more output now.
 */
static void ppp_async_process(unsigned long arg)
{
<------>struct asyncppp *ap = (struct asyncppp *) arg;
<------>struct sk_buff *skb;
 
<------>/* process received packets */
<------>while ((skb = skb_dequeue(&ap->rqueue)) != NULL) {
<------><------>if (skb->cb[0])
<------><------><------>ppp_input_error(&ap->chan, 0);
<------><------>ppp_input(&ap->chan, skb);
<------>}
 
<------>/* try to push more stuff out */
<------>if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_async_push(ap))
<------><------>ppp_output_wakeup(&ap->chan);
}
 
/*
 * Procedures for encapsulation and framing.
 */
 
/*
 * Procedure to encode the data for async serial transmission.
 * Does octet stuffing (escaping), puts the address/control bytes
 * on if A/C compression is disabled, and does protocol compression.
 * Assumes ap->tpkt != 0 on entry.
 * Returns 1 if we finished the current frame, 0 otherwise.
 */
 
#define PUT_BYTE(ap, buf, c, islcp)	do {		\
<------>if ((islcp && c < 0x20) || (ap->xaccm[c >> 5] & (1 << (c & 0x1f)))) {\
<------><------>*buf++ = PPP_ESCAPE;			\
<------><------>*buf++ = c ^ PPP_TRANS;			\
<------>} else						\
<------><------>*buf++ = c;				\
} while (0)
 
static int
ppp_async_encode(struct asyncppp *ap)
{
<------>int fcs, i, count, c, proto;
<------>unsigned char *buf, *buflim;
<------>unsigned char *data;
<------>int islcp;
 
<------>buf = ap->obuf;
<------>ap->olim = buf;
<------>ap->optr = buf;
<------>i = ap->tpkt_pos;
<------>data = ap->tpkt->data;
<------>count = ap->tpkt->len;
<------>fcs = ap->tfcs;
<------>proto = get_unaligned_be16(data);
 
<------>/*
<------> * LCP packets with code values between 1 (configure-reqest)
<------> * and 7 (code-reject) must be sent as though no options
<------> * had been negotiated.
<------> */
<------>islcp = proto == PPP_LCP && 1 <= data[2] && data[2] <= 7;
 
<------>if (i == 0) {
<------><------>if (islcp)
<------><------><------>async_lcp_peek(ap, data, count, 0);
 
<------><------>/*
<------><------> * Start of a new packet - insert the leading FLAG
<------><------> * character if necessary.
<------><------> */
<------><------>if (islcp || flag_time == 0 ||
<------><------>    time_after_eq(jiffies, ap->last_xmit + flag_time))
<------><------><------>*buf++ = PPP_FLAG;
<------><------>ap->last_xmit = jiffies;
<------><------>fcs = PPP_INITFCS;
 
<------><------>/*
<------><------> * Put in the address/control bytes if necessary
<------><------> */
<------><------>if ((ap->flags & SC_COMP_AC) == 0 || islcp) {
<------><------><------>PUT_BYTE(ap, buf, 0xff, islcp);
<------><------><------>fcs = PPP_FCS(fcs, 0xff);
<------><------><------>PUT_BYTE(ap, buf, 0x03, islcp);
<------><------><------>fcs = PPP_FCS(fcs, 0x03);
<------><------>}
<------>}
 
<------>/*
<------> * Once we put in the last byte, we need to put in the FCS
<------> * and closing flag, so make sure there is at least 7 bytes
<------> * of free space in the output buffer.
<------> */
<------>buflim = ap->obuf + OBUFSIZE - 6;
<------>while (i < count && buf < buflim) {
<------><------>c = data[i++];
<------><------>if (i == 1 && c == 0 && (ap->flags & SC_COMP_PROT))
<------><------><------>continue;	/* compress protocol field */
<------><------>fcs = PPP_FCS(fcs, c);
<------><------>PUT_BYTE(ap, buf, c, islcp);
<------>}
 
<------>if (i < count) {
<------><------>/*
<------><------> * Remember where we are up to in this packet.
<------><------> */
<------><------>ap->olim = buf;
<------><------>ap->tpkt_pos = i;
<------><------>ap->tfcs = fcs;
<------><------>return 0;
<------>}
 
<------>/*
<------> * We have finished the packet.  Add the FCS and flag.
<------> */
<------>fcs = ~fcs;
<------>c = fcs & 0xff;
<------>PUT_BYTE(ap, buf, c, islcp);
<------>c = (fcs >> 8) & 0xff;
<------>PUT_BYTE(ap, buf, c, islcp);
<------>*buf++ = PPP_FLAG;
<------>ap->olim = buf;
 
<------>consume_skb(ap->tpkt);
<------>ap->tpkt = NULL;
<------>return 1;
}
 
/*
 * Transmit-side routines.
 */
 
/*
 * Send a packet to the peer over an async tty line.
 * Returns 1 iff the packet was accepted.
 * If the packet was not accepted, we will call ppp_output_wakeup
 * at some later time.
 */
static int
ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb)
{
<------>struct asyncppp *ap = chan->private;
 
<------>ppp_async_push(ap);
 
<------>if (test_and_set_bit(XMIT_FULL, &ap->xmit_flags))
<------><------>return 0;	/* already full */
<------>ap->tpkt = skb;
<------>ap->tpkt_pos = 0;
 
<------>ppp_async_push(ap);
<------>return 1;
}
 
/*
 * Push as much data as possible out to the tty.
 */
static int
ppp_async_push(struct asyncppp *ap)
{
<------>int avail, sent, done = 0;
<------>struct tty_struct *tty = ap->tty;
<------>int tty_stuffed = 0;
 
<------>/*
<------> * We can get called recursively here if the tty write
<------> * function calls our wakeup function.  This can happen
<------> * for example on a pty with both the master and slave
<------> * set to PPP line discipline.
<------> * We use the XMIT_BUSY bit to detect this and get out,
<------> * leaving the XMIT_WAKEUP bit set to tell the other
<------> * instance that it may now be able to write more now.
<------> */
<------>if (test_and_set_bit(XMIT_BUSY, &ap->xmit_flags))
<------><------>return 0;
<------>spin_lock_bh(&ap->xmit_lock);
<------>for (;;) {
<------><------>if (test_and_clear_bit(XMIT_WAKEUP, &ap->xmit_flags))
<------><------><------>tty_stuffed = 0;
<------><------>if (!tty_stuffed && ap->optr < ap->olim) {
<------><------><------>avail = ap->olim - ap->optr;
<------><------><------>set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
<------><------><------>sent = tty->ops->write(tty, ap->optr, avail);
<------><------><------>if (sent < 0)
<------><------><------><------>goto flush;	/* error, e.g. loss of CD */
<------><------><------>ap->optr += sent;
<------><------><------>if (sent < avail)
<------><------><------><------>tty_stuffed = 1;
<------><------><------>continue;
<------><------>}
<------><------>if (ap->optr >= ap->olim && ap->tpkt) {
<------><------><------>if (ppp_async_encode(ap)) {
<------><------><------><------>/* finished processing ap->tpkt */
<------><------><------><------>clear_bit(XMIT_FULL, &ap->xmit_flags);
<------><------><------><------>done = 1;
<------><------><------>}
<------><------><------>continue;
<------><------>}
<------><------>/*
<------><------> * We haven't made any progress this time around.
<------><------> * Clear XMIT_BUSY to let other callers in, but
<------><------> * after doing so we have to check if anyone set
<------><------> * XMIT_WAKEUP since we last checked it.  If they
<------><------> * did, we should try again to set XMIT_BUSY and go
<------><------> * around again in case XMIT_BUSY was still set when
<------><------> * the other caller tried.
<------><------> */
<------><------>clear_bit(XMIT_BUSY, &ap->xmit_flags);
<------><------>/* any more work to do? if not, exit the loop */
<------><------>if (!(test_bit(XMIT_WAKEUP, &ap->xmit_flags) ||
<------><------>      (!tty_stuffed && ap->tpkt)))
<------><------><------>break;
<------><------>/* more work to do, see if we can do it now */
<------><------>if (test_and_set_bit(XMIT_BUSY, &ap->xmit_flags))
<------><------><------>break;
<------>}
<------>spin_unlock_bh(&ap->xmit_lock);
<------>return done;
 
flush:
<------>clear_bit(XMIT_BUSY, &ap->xmit_flags);
<------>if (ap->tpkt) {
<------><------>kfree_skb(ap->tpkt);
<------><------>ap->tpkt = NULL;
<------><------>clear_bit(XMIT_FULL, &ap->xmit_flags);
<------><------>done = 1;
<------>}
<------>ap->optr = ap->olim;
<------>spin_unlock_bh(&ap->xmit_lock);
<------>return done;
}
 
/*
 * Flush output from our internal buffers.
 * Called for the TCFLSH ioctl. Can be entered in parallel
 * but this is covered by the xmit_lock.
 */
static void
ppp_async_flush_output(struct asyncppp *ap)
{
<------>int done = 0;
 
<------>spin_lock_bh(&ap->xmit_lock);
<------>ap->optr = ap->olim;
<------>if (ap->tpkt != NULL) {
<------><------>kfree_skb(ap->tpkt);
<------><------>ap->tpkt = NULL;
<------><------>clear_bit(XMIT_FULL, &ap->xmit_flags);
<------><------>done = 1;
<------>}
<------>spin_unlock_bh(&ap->xmit_lock);
<------>if (done)
<------><------>ppp_output_wakeup(&ap->chan);
}
 
/*
 * Receive-side routines.
 */
 
/* see how many ordinary chars there are at the start of buf */
static inline int
scan_ordinary(struct asyncppp *ap, const unsigned char *buf, int count)
{
<------>int i, c;
 
<------>for (i = 0; i < count; ++i) {
<------><------>c = buf[i];
<------><------>if (c == PPP_ESCAPE || c == PPP_FLAG ||
<------><------>    (c < 0x20 && (ap->raccm & (1 << c)) != 0))
<------><------><------>break;
<------>}
<------>return i;
}
 
/* called when a flag is seen - do end-of-packet processing */
static void
process_input_packet(struct asyncppp *ap)
{
<------>struct sk_buff *skb;
<------>unsigned char *p;
<------>unsigned int len, fcs;
 
<------>skb = ap->rpkt;
<------>if (ap->state & (SC_TOSS | SC_ESCAPE))
<------><------>goto err;
 
<------>if (skb == NULL)
<------><------>return;		/* 0-length packet */
 
<------>/* check the FCS */
<------>p = skb->data;
<------>len = skb->len;
<------>if (len < 3)
<------><------>goto err;	/* too short */
<------>fcs = PPP_INITFCS;
<------>for (; len > 0; --len)
<------><------>fcs = PPP_FCS(fcs, *p++);
<------>if (fcs != PPP_GOODFCS)
<------><------>goto err;	/* bad FCS */
<------>skb_trim(skb, skb->len - 2);
 
<------>/* check for address/control and protocol compression */
<------>p = skb->data;
<------>if (p[0] == PPP_ALLSTATIONS) {
<------><------>/* chop off address/control */
<------><------>if (p[1] != PPP_UI || skb->len < 3)
<------><------><------>goto err;
<------><------>p = skb_pull(skb, 2);
<------>}
 
<------>/* If protocol field is not compressed, it can be LCP packet */
<------>if (!(p[0] & 0x01)) {
<------><------>unsigned int proto;
 
<------><------>if (skb->len < 2)
<------><------><------>goto err;
<------><------>proto = (p[0] << 8) + p[1];
<------><------>if (proto == PPP_LCP)
<------><------><------>async_lcp_peek(ap, p, skb->len, 1);
<------>}
 
<------>/* queue the frame to be processed */
<------>skb->cb[0] = ap->state;
<------>skb_queue_tail(&ap->rqueue, skb);
<------>ap->rpkt = NULL;
<------>ap->state = 0;
<------>return;
 
 err:
<------>/* frame had an error, remember that, reset SC_TOSS & SC_ESCAPE */
<------>ap->state = SC_PREV_ERROR;
<------>if (skb) {
<------><------>/* make skb appear as freshly allocated */
<------><------>skb_trim(skb, 0);
<------><------>skb_reserve(skb, - skb_headroom(skb));
<------>}
}
 
/* Called when the tty driver has data for us. Runs parallel with the
   other ldisc functions but will not be re-entered */
 
static void
ppp_async_input(struct asyncppp *ap, const unsigned char *buf,
<------><------>char *flags, int count)
{
<------>struct sk_buff *skb;
<------>int c, i, j, n, s, f;
<------>unsigned char *sp;
 
<------>/* update bits used for 8-bit cleanness detection */
<------>if (~ap->rbits & SC_RCV_BITS) {
<------><------>s = 0;
<------><------>for (i = 0; i < count; ++i) {
<------><------><------>c = buf[i];
<------><------><------>if (flags && flags[i] != 0)
<------><------><------><------>continue;
<------><------><------>s |= (c & 0x80)? SC_RCV_B7_1: SC_RCV_B7_0;
<------><------><------>c = ((c >> 4) ^ c) & 0xf;
<------><------><------>s |= (0x6996 & (1 << c))? SC_RCV_ODDP: SC_RCV_EVNP;
<------><------>}
<------><------>ap->rbits |= s;
<------>}
 
<------>while (count > 0) {
<------><------>/* scan through and see how many chars we can do in bulk */
<------><------>if ((ap->state & SC_ESCAPE) && buf[0] == PPP_ESCAPE)
<------><------><------>n = 1;
<------><------>else
<------><------><------>n = scan_ordinary(ap, buf, count);
 
<------><------>f = 0;
<------><------>if (flags && (ap->state & SC_TOSS) == 0) {
<------><------><------>/* check the flags to see if any char had an error */
<------><------><------>for (j = 0; j < n; ++j)
<------><------><------><------>if ((f = flags[j]) != 0)
<------><------><------><------><------>break;
<------><------>}
<------><------>if (f != 0) {
<------><------><------>/* start tossing */
<------><------><------>ap->state |= SC_TOSS;
 
<------><------>} else if (n > 0 && (ap->state & SC_TOSS) == 0) {
<------><------><------>/* stuff the chars in the skb */
<------><------><------>skb = ap->rpkt;
<------><------><------>if (!skb) {
<------><------><------><------>skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2);
<------><------><------><------>if (!skb)
<------><------><------><------><------>goto nomem;
<------><------><------><------>ap->rpkt = skb;
<------><------><------>}
<------><------><------>if (skb->len == 0) {
<------><------><------><------>/* Try to get the payload 4-byte aligned.
<------><------><------><------> * This should match the
<------><------><------><------> * PPP_ALLSTATIONS/PPP_UI/compressed tests in
<------><------><------><------> * process_input_packet, but we do not have
<------><------><------><------> * enough chars here to test buf[1] and buf[2].
<------><------><------><------> */
<------><------><------><------>if (buf[0] != PPP_ALLSTATIONS)
<------><------><------><------><------>skb_reserve(skb, 2 + (buf[0] & 1));
<------><------><------>}
<------><------><------>if (n > skb_tailroom(skb)) {
<------><------><------><------>/* packet overflowed MRU */
<------><------><------><------>ap->state |= SC_TOSS;
<------><------><------>} else {
<------><------><------><------>sp = skb_put_data(skb, buf, n);
<------><------><------><------>if (ap->state & SC_ESCAPE) {
<------><------><------><------><------>sp[0] ^= PPP_TRANS;
<------><------><------><------><------>ap->state &= ~SC_ESCAPE;
<------><------><------><------>}
<------><------><------>}
<------><------>}
 
<------><------>if (n >= count)
<------><------><------>break;
 
<------><------>c = buf[n];
<------><------>if (flags != NULL && flags[n] != 0) {
<------><------><------>ap->state |= SC_TOSS;
<------><------>} else if (c == PPP_FLAG) {
<------><------><------>process_input_packet(ap);
<------><------>} else if (c == PPP_ESCAPE) {
<------><------><------>ap->state |= SC_ESCAPE;
<------><------>} else if (I_IXON(ap->tty)) {
<------><------><------>if (c == START_CHAR(ap->tty))
<------><------><------><------>start_tty(ap->tty);
<------><------><------>else if (c == STOP_CHAR(ap->tty))
<------><------><------><------>stop_tty(ap->tty);
<------><------>}
<------><------>/* otherwise it's a char in the recv ACCM */
<------><------>++n;
 
<------><------>buf += n;
<------><------>if (flags)
<------><------><------>flags += n;
<------><------>count -= n;
<------>}
<------>return;
 
 nomem:
<------>printk(KERN_ERR "PPPasync: no memory (input pkt)\n");
<------>ap->state |= SC_TOSS;
}
 
/*
 * We look at LCP frames going past so that we can notice
 * and react to the LCP configure-ack from the peer.
 * In the situation where the peer has been sent a configure-ack
 * already, LCP is up once it has sent its configure-ack
 * so the immediately following packet can be sent with the
 * configured LCP options.  This allows us to process the following
 * packet correctly without pppd needing to respond quickly.
 *
 * We only respond to the received configure-ack if we have just
 * sent a configure-request, and the configure-ack contains the
 * same data (this is checked using a 16-bit crc of the data).
 */
#define CONFREQ		1	/* LCP code field values */
#define CONFACK		2
#define LCP_MRU		1	/* LCP option numbers */
#define LCP_ASYNCMAP	2
 
static void async_lcp_peek(struct asyncppp *ap, unsigned char *data,
<------><------><------>   int len, int inbound)
{
<------>int dlen, fcs, i, code;
<------>u32 val;
 
<------>data += 2;		/* skip protocol bytes */
<------>len -= 2;
<------>if (len < 4)		/* 4 = code, ID, length */
<------><------>return;
<------>code = data[0];
<------>if (code != CONFACK && code != CONFREQ)
<------><------>return;
<------>dlen = get_unaligned_be16(data + 2);
<------>if (len < dlen)
<------><------>return;		/* packet got truncated or length is bogus */
 
<------>if (code == (inbound? CONFACK: CONFREQ)) {
<------><------>/*
<------><------> * sent confreq or received confack:
<------><------> * calculate the crc of the data from the ID field on.
<------><------> */
<------><------>fcs = PPP_INITFCS;
<------><------>for (i = 1; i < dlen; ++i)
<------><------><------>fcs = PPP_FCS(fcs, data[i]);
 
<------><------>if (!inbound) {
<------><------><------>/* outbound confreq - remember the crc for later */
<------><------><------>ap->lcp_fcs = fcs;
<------><------><------>return;
<------><------>}
 
<------><------>/* received confack, check the crc */
<------><------>fcs ^= ap->lcp_fcs;
<------><------>ap->lcp_fcs = -1;
<------><------>if (fcs != 0)
<------><------><------>return;
<------>} else if (inbound)
<------><------>return;	/* not interested in received confreq */
 
<------>/* process the options in the confack */
<------>data += 4;
<------>dlen -= 4;
<------>/* data[0] is code, data[1] is length */
<------>while (dlen >= 2 && dlen >= data[1] && data[1] >= 2) {
<------><------>switch (data[0]) {
<------><------>case LCP_MRU:
<------><------><------>val = get_unaligned_be16(data + 2);
<------><------><------>if (inbound)
<------><------><------><------>ap->mru = val;
<------><------><------>else
<------><------><------><------>ap->chan.mtu = val;
<------><------><------>break;
<------><------>case LCP_ASYNCMAP:
<------><------><------>val = get_unaligned_be32(data + 2);
<------><------><------>if (inbound)
<------><------><------><------>ap->raccm = val;
<------><------><------>else
<------><------><------><------>ap->xaccm[0] = val;
<------><------><------>break;
<------><------>}
<------><------>dlen -= data[1];
<------><------>data += data[1];
<------>}
}
 
static void __exit ppp_async_cleanup(void)
{
<------>if (tty_unregister_ldisc(N_PPP) != 0)
<------><------>printk(KERN_ERR "failed to unregister PPP line discipline\n");
}
 
module_init(ppp_async_init);
module_exit(ppp_async_cleanup);