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slip.c
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/*
* slip.c This module implements the SLIP protocol for kernel-based
* devices like TTY. It interfaces between a raw TTY, and the
* kernel's INET protocol layers.
*
* Version: @(#)slip.c 0.8.3 12/24/94
*
* Authors: Laurence Culhane, <[email protected]>
* Fred N. van Kempen, <[email protected]>
*
* Fixes:
* Alan Cox : Sanity checks and avoid tx overruns.
* Has a new sl->mtu field.
* Alan Cox : Found cause of overrun. ifconfig sl0 mtu upwards.
* Driver now spots this and grows/shrinks its buffers(hack!).
* Memory leak if you run out of memory setting up a slip driver fixed.
* Matt Dillon : Printable slip (borrowed from NET2E)
* Pauline Middelink : Slip driver fixes.
* Alan Cox : Honours the old SL_COMPRESSED flag
* Alan Cox : KISS AX.25 and AXUI IP support
* Michael Riepe : Automatic CSLIP recognition added
* Charles Hedrick : CSLIP header length problem fix.
* Alan Cox : Corrected non-IP cases of the above.
* Alan Cox : Now uses hardware type as per FvK.
* Alan Cox : Default to 192.168.0.0 (RFC 1597)
* A.N.Kuznetsov : dev_tint() recursion fix.
* Dmitry Gorodchanin : SLIP memory leaks
* Dmitry Gorodchanin : Code cleanup. Reduce tty driver
* buffering from 4096 to 256 bytes.
* Improving SLIP response time.
* CONFIG_SLIP_MODE_SLIP6.
* ifconfig sl? up & down now works correctly.
* Modularization.
* Alan Cox : Oops - fix AX.25 buffer lengths
* Dmitry Gorodchanin : Even more cleanups. Preserve CSLIP
* statistics. Include CSLIP code only
* if it really needed.
* Alan Cox : Free slhc buffers in the right place.
* Alan Cox : Allow for digipeated IP over AX.25
* Matti Aarnio : Dynamic SLIP devices, with ideas taken
* from Jim Freeman's <[email protected]>
* dynamic PPP devices. We do NOT kfree()
* device entries, just reg./unreg. them
* as they are needed. We kfree() them
* at module cleanup.
* With MODULE-loading ``insmod'', user can
* issue parameter: slip_maxdev=1024
* (Or how much he/she wants.. Default is 256)
* * Stanislav Voronyi : Slip line checking, with ideas taken
* from multislip BSDI driver which was written
* by Igor Chechik, RELCOM Corp. Only algorithms
* have been ported to Linux SLIP driver.
* Vitaly E. Lavrov : Sane behaviour on tty hangup.
* Alexey Kuznetsov : Cleanup interfaces to tty&netdevice modules.
*/
#define SL_CHECK_TRANSMIT
#include <linux/config.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <linux/bitops.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/in.h>
#include <linux/tty.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/if_arp.h>
#include <linux/if_slip.h>
#include <linux/delay.h>
#include <linux/init.h>
#include "slip.h"
#ifdef CONFIG_INET
#include <linux/ip.h>
#include <linux/tcp.h>
#include <net/slhc_vj.h>
#endif
#define SLIP_VERSION "0.8.4-NET3.019-NEWTTY"
static struct net_device **slip_devs;
static int slip_maxdev = SL_NRUNIT;
module_param(slip_maxdev, int, 0);
MODULE_PARM_DESC(slip_maxdev, "Maximum number of slip devices");
static int slip_esc(unsigned char *p, unsigned char *d, int len);
static void slip_unesc(struct slip *sl, unsigned char c);
#ifdef CONFIG_SLIP_MODE_SLIP6
static int slip_esc6(unsigned char *p, unsigned char *d, int len);
static void slip_unesc6(struct slip *sl, unsigned char c);
#endif
#ifdef CONFIG_SLIP_SMART
static void sl_keepalive(unsigned long sls);
static void sl_outfill(unsigned long sls);
static int sl_ioctl(struct net_device *dev,struct ifreq *rq,int cmd);
#endif
/********************************
* Buffer administration routines:
* sl_alloc_bufs()
* sl_free_bufs()
* sl_realloc_bufs()
*
* NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because
* sl_realloc_bufs provides strong atomicity and reallocation
* on actively running device.
*********************************/
/*
Allocate channel buffers.
*/
static int
sl_alloc_bufs(struct slip *sl, int mtu)
{
int err = -ENOBUFS;
unsigned long len;
char * rbuff = NULL;
char * xbuff = NULL;
#ifdef SL_INCLUDE_CSLIP
char * cbuff = NULL;
struct slcompress *slcomp = NULL;
#endif
/*
* Allocate the SLIP frame buffers:
*
* rbuff Receive buffer.
* xbuff Transmit buffer.
* cbuff Temporary compression buffer.
*/
len = mtu * 2;
/*
* allow for arrival of larger UDP packets, even if we say not to
* also fixes a bug in which SunOS sends 512-byte packets even with
* an MSS of 128
*/
if (len < 576 * 2)
len = 576 * 2;
rbuff = kmalloc(len + 4, GFP_KERNEL);
if (rbuff == NULL)
goto err_exit;
xbuff = kmalloc(len + 4, GFP_KERNEL);
if (xbuff == NULL)
goto err_exit;
#ifdef SL_INCLUDE_CSLIP
cbuff = kmalloc(len + 4, GFP_KERNEL);
if (cbuff == NULL)
goto err_exit;
slcomp = slhc_init(16, 16);
if (slcomp == NULL)
goto err_exit;
#endif
spin_lock_bh(&sl->lock);
if (sl->tty == NULL) {
spin_unlock_bh(&sl->lock);
err = -ENODEV;
goto err_exit;
}
sl->mtu = mtu;
sl->buffsize = len;
sl->rcount = 0;
sl->xleft = 0;
rbuff = xchg(&sl->rbuff, rbuff);
xbuff = xchg(&sl->xbuff, xbuff);
#ifdef SL_INCLUDE_CSLIP
cbuff = xchg(&sl->cbuff, cbuff);
slcomp = xchg(&sl->slcomp, slcomp);
#ifdef CONFIG_SLIP_MODE_SLIP6
sl->xdata = 0;
sl->xbits = 0;
#endif
#endif
spin_unlock_bh(&sl->lock);
err = 0;
/* Cleanup */
err_exit:
#ifdef SL_INCLUDE_CSLIP
kfree(cbuff);
if (slcomp)
slhc_free(slcomp);
#endif
kfree(xbuff);
kfree(rbuff);
return err;
}
/* Free a SLIP channel buffers. */
static void
sl_free_bufs(struct slip *sl)
{
/* Free all SLIP frame buffers. */
kfree(xchg(&sl->rbuff, NULL));
kfree(xchg(&sl->xbuff, NULL));
#ifdef SL_INCLUDE_CSLIP
kfree(xchg(&sl->cbuff, NULL));
slhc_free(xchg(&sl->slcomp, NULL));
#endif
}
/*
Reallocate slip channel buffers.
*/
static int sl_realloc_bufs(struct slip *sl, int mtu)
{
int err = 0;
struct net_device *dev = sl->dev;
unsigned char *xbuff, *rbuff;
#ifdef SL_INCLUDE_CSLIP
unsigned char *cbuff;
#endif
int len = mtu * 2;
/*
* allow for arrival of larger UDP packets, even if we say not to
* also fixes a bug in which SunOS sends 512-byte packets even with
* an MSS of 128
*/
if (len < 576 * 2)
len = 576 * 2;
xbuff = (unsigned char *) kmalloc (len + 4, GFP_ATOMIC);
rbuff = (unsigned char *) kmalloc (len + 4, GFP_ATOMIC);
#ifdef SL_INCLUDE_CSLIP
cbuff = (unsigned char *) kmalloc (len + 4, GFP_ATOMIC);
#endif
#ifdef SL_INCLUDE_CSLIP
if (xbuff == NULL || rbuff == NULL || cbuff == NULL) {
#else
if (xbuff == NULL || rbuff == NULL) {
#endif
if (mtu >= sl->mtu) {
printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n",
dev->name);
err = -ENOBUFS;
}
goto done;
}
spin_lock_bh(&sl->lock);
err = -ENODEV;
if (sl->tty == NULL)
goto done_on_bh;
xbuff = xchg(&sl->xbuff, xbuff);
rbuff = xchg(&sl->rbuff, rbuff);
#ifdef SL_INCLUDE_CSLIP
cbuff = xchg(&sl->cbuff, cbuff);
#endif
if (sl->xleft) {
if (sl->xleft <= len) {
memcpy(sl->xbuff, sl->xhead, sl->xleft);
} else {
sl->xleft = 0;
sl->tx_dropped++;
}
}
sl->xhead = sl->xbuff;
if (sl->rcount) {
if (sl->rcount <= len) {
memcpy(sl->rbuff, rbuff, sl->rcount);
} else {
sl->rcount = 0;
sl->rx_over_errors++;
set_bit(SLF_ERROR, &sl->flags);
}
}
sl->mtu = mtu;
dev->mtu = mtu;
sl->buffsize = len;
err = 0;
done_on_bh:
spin_unlock_bh(&sl->lock);
done:
kfree(xbuff);
kfree(rbuff);
#ifdef SL_INCLUDE_CSLIP
kfree(cbuff);
#endif
return err;
}
/* Set the "sending" flag. This must be atomic hence the set_bit. */
static inline void
sl_lock(struct slip *sl)
{
netif_stop_queue(sl->dev);
}
/* Clear the "sending" flag. This must be atomic, hence the ASM. */
static inline void
sl_unlock(struct slip *sl)
{
netif_wake_queue(sl->dev);
}
/* Send one completely decapsulated IP datagram to the IP layer. */
static void
sl_bump(struct slip *sl)
{
struct sk_buff *skb;
int count;
count = sl->rcount;
#ifdef SL_INCLUDE_CSLIP
if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) {
unsigned char c;
if ((c = sl->rbuff[0]) & SL_TYPE_COMPRESSED_TCP) {
/* ignore compressed packets when CSLIP is off */
if (!(sl->mode & SL_MODE_CSLIP)) {
printk(KERN_WARNING "%s: compressed packet ignored\n", sl->dev->name);
return;
}
/* make sure we've reserved enough space for uncompress to use */
if (count + 80 > sl->buffsize) {
sl->rx_over_errors++;
return;
}
count = slhc_uncompress(sl->slcomp, sl->rbuff, count);
if (count <= 0) {
return;
}
} else if (c >= SL_TYPE_UNCOMPRESSED_TCP) {
if (!(sl->mode & SL_MODE_CSLIP)) {
/* turn on header compression */
sl->mode |= SL_MODE_CSLIP;
sl->mode &= ~SL_MODE_ADAPTIVE;
printk(KERN_INFO "%s: header compression turned on\n", sl->dev->name);
}
sl->rbuff[0] &= 0x4f;
if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0) {
return;
}
}
}
#endif /* SL_INCLUDE_CSLIP */
sl->rx_bytes+=count;
skb = dev_alloc_skb(count);
if (skb == NULL) {
printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", sl->dev->name);
sl->rx_dropped++;
return;
}
skb->dev = sl->dev;
memcpy(skb_put(skb,count), sl->rbuff, count);
skb->mac.raw=skb->data;
skb->protocol=htons(ETH_P_IP);
netif_rx(skb);
sl->dev->last_rx = jiffies;
sl->rx_packets++;
}
/* Encapsulate one IP datagram and stuff into a TTY queue. */
static void
sl_encaps(struct slip *sl, unsigned char *icp, int len)
{
unsigned char *p;
int actual, count;
if (len > sl->mtu) { /* Sigh, shouldn't occur BUT ... */
printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name);
sl->tx_dropped++;
sl_unlock(sl);
return;
}
p = icp;
#ifdef SL_INCLUDE_CSLIP
if (sl->mode & SL_MODE_CSLIP) {
len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1);
}
#endif
#ifdef CONFIG_SLIP_MODE_SLIP6
if(sl->mode & SL_MODE_SLIP6)
count = slip_esc6(p, (unsigned char *) sl->xbuff, len);
else
#endif
count = slip_esc(p, (unsigned char *) sl->xbuff, len);
/* Order of next two lines is *very* important.
* When we are sending a little amount of data,
* the transfer may be completed inside driver.write()
* routine, because it's running with interrupts enabled.
* In this case we *never* got WRITE_WAKEUP event,
* if we did not request it before write operation.
* 14 Oct 1994 Dmitry Gorodchanin.
*/
sl->tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
actual = sl->tty->driver->write(sl->tty, sl->xbuff, count);
#ifdef SL_CHECK_TRANSMIT
sl->dev->trans_start = jiffies;
#endif
sl->xleft = count - actual;
sl->xhead = sl->xbuff + actual;
#ifdef CONFIG_SLIP_SMART
/* VSV */
clear_bit(SLF_OUTWAIT, &sl->flags); /* reset outfill flag */
#endif
}
/*
* Called by the driver when there's room for more data. If we have
* more packets to send, we send them here.
*/
static void slip_write_wakeup(struct tty_struct *tty)
{
int actual;
struct slip *sl = (struct slip *) tty->disc_data;
/* First make sure we're connected. */
if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev)) {
return;
}
if (sl->xleft <= 0) {
/* Now serial buffer is almost free & we can start
* transmission of another packet */
sl->tx_packets++;
tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
sl_unlock(sl);
return;
}
actual = tty->driver->write(tty, sl->xhead, sl->xleft);
sl->xleft -= actual;
sl->xhead += actual;
}
static void sl_tx_timeout(struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
spin_lock(&sl->lock);
if (netif_queue_stopped(dev)) {
if (!netif_running(dev))
goto out;
/* May be we must check transmitter timeout here ?
* 14 Oct 1994 Dmitry Gorodchanin.
*/
#ifdef SL_CHECK_TRANSMIT
if (time_before(jiffies, dev->trans_start + 20 * HZ)) {
/* 20 sec timeout not reached */
goto out;
}
printk(KERN_WARNING "%s: transmit timed out, %s?\n", dev->name,
(sl->tty->driver->chars_in_buffer(sl->tty) || sl->xleft) ?
"bad line quality" : "driver error");
sl->xleft = 0;
sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
sl_unlock(sl);
#endif
}
out:
spin_unlock(&sl->lock);
}
/* Encapsulate an IP datagram and kick it into a TTY queue. */
static int
sl_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
spin_lock(&sl->lock);
if (!netif_running(dev)) {
spin_unlock(&sl->lock);
printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
dev_kfree_skb(skb);
return 0;
}
if (sl->tty == NULL) {
spin_unlock(&sl->lock);
dev_kfree_skb(skb);
return 0;
}
sl_lock(sl);
sl->tx_bytes+=skb->len;
sl_encaps(sl, skb->data, skb->len);
spin_unlock(&sl->lock);
dev_kfree_skb(skb);
return 0;
}
/******************************************
* Routines looking at netdevice side.
******************************************/
/* Netdevice UP -> DOWN routine */
static int
sl_close(struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
spin_lock_bh(&sl->lock);
if (sl->tty) {
/* TTY discipline is running. */
sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
}
netif_stop_queue(dev);
sl->rcount = 0;
sl->xleft = 0;
spin_unlock_bh(&sl->lock);
return 0;
}
/* Netdevice DOWN -> UP routine */
static int sl_open(struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
if (sl->tty==NULL)
return -ENODEV;
sl->flags &= (1 << SLF_INUSE);
netif_start_queue(dev);
return 0;
}
/* Netdevice change MTU request */
static int sl_change_mtu(struct net_device *dev, int new_mtu)
{
struct slip *sl = netdev_priv(dev);
if (new_mtu < 68 || new_mtu > 65534)
return -EINVAL;
if (new_mtu != dev->mtu)
return sl_realloc_bufs(sl, new_mtu);
return 0;
}
/* Netdevice get statistics request */
static struct net_device_stats *
sl_get_stats(struct net_device *dev)
{
static struct net_device_stats stats;
struct slip *sl = netdev_priv(dev);
#ifdef SL_INCLUDE_CSLIP
struct slcompress *comp;
#endif
memset(&stats, 0, sizeof(struct net_device_stats));
stats.rx_packets = sl->rx_packets;
stats.tx_packets = sl->tx_packets;
stats.rx_bytes = sl->rx_bytes;
stats.tx_bytes = sl->tx_bytes;
stats.rx_dropped = sl->rx_dropped;
stats.tx_dropped = sl->tx_dropped;
stats.tx_errors = sl->tx_errors;
stats.rx_errors = sl->rx_errors;
stats.rx_over_errors = sl->rx_over_errors;
#ifdef SL_INCLUDE_CSLIP
stats.rx_fifo_errors = sl->rx_compressed;
stats.tx_fifo_errors = sl->tx_compressed;
stats.collisions = sl->tx_misses;
comp = sl->slcomp;
if (comp) {
stats.rx_fifo_errors += comp->sls_i_compressed;
stats.rx_dropped += comp->sls_i_tossed;
stats.tx_fifo_errors += comp->sls_o_compressed;
stats.collisions += comp->sls_o_misses;
}
#endif /* CONFIG_INET */
return (&stats);
}
/* Netdevice register callback */
static int sl_init(struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
/*
* Finish setting up the DEVICE info.
*/
dev->mtu = sl->mtu;
dev->type = ARPHRD_SLIP + sl->mode;
#ifdef SL_CHECK_TRANSMIT
dev->tx_timeout = sl_tx_timeout;
dev->watchdog_timeo = 20*HZ;
#endif
return 0;
}
static void sl_uninit(struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
sl_free_bufs(sl);
}
static void sl_setup(struct net_device *dev)
{
dev->init = sl_init;
dev->uninit = sl_uninit;
dev->open = sl_open;
dev->destructor = free_netdev;
dev->stop = sl_close;
dev->get_stats = sl_get_stats;
dev->change_mtu = sl_change_mtu;
dev->hard_start_xmit = sl_xmit;
#ifdef CONFIG_SLIP_SMART
dev->do_ioctl = sl_ioctl;
#endif
dev->hard_header_len = 0;
dev->addr_len = 0;
dev->tx_queue_len = 10;
SET_MODULE_OWNER(dev);
/* New-style flags. */
dev->flags = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST;
}
/******************************************
Routines looking at TTY side.
******************************************/
static int slip_receive_room(struct tty_struct *tty)
{
return 65536; /* We can handle an infinite amount of data. :-) */
}
/*
* Handle the 'receiver data ready' interrupt.
* This function is called by the 'tty_io' module in the kernel when
* a block of SLIP data has been received, which can now be decapsulated
* and sent on to some IP layer for further processing. This will not
* be re-entered while running but other ldisc functions may be called
* in parallel
*/
static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
{
struct slip *sl = (struct slip *) tty->disc_data;
if (!sl || sl->magic != SLIP_MAGIC ||
!netif_running(sl->dev))
return;
/* Read the characters out of the buffer */
while (count--) {
if (fp && *fp++) {
if (!test_and_set_bit(SLF_ERROR, &sl->flags)) {
sl->rx_errors++;
}
cp++;
continue;
}
#ifdef CONFIG_SLIP_MODE_SLIP6
if (sl->mode & SL_MODE_SLIP6)
slip_unesc6(sl, *cp++);
else
#endif
slip_unesc(sl, *cp++);
}
}
/************************************
* slip_open helper routines.
************************************/
/* Collect hanged up channels */
static void sl_sync(void)
{
int i;
struct net_device *dev;
struct slip *sl;
for (i = 0; i < slip_maxdev; i++) {
if ((dev = slip_devs[i]) == NULL)
break;
sl = netdev_priv(dev);
if (sl->tty || sl->leased)
continue;
if (dev->flags&IFF_UP)
dev_close(dev);
}
}
/* Find a free SLIP channel, and link in this `tty' line. */
static struct slip *
sl_alloc(dev_t line)
{
int i;
int sel = -1;
int score = -1;
struct net_device *dev = NULL;
struct slip *sl;
if (slip_devs == NULL)
return NULL; /* Master array missing ! */
for (i = 0; i < slip_maxdev; i++) {
dev = slip_devs[i];
if (dev == NULL)
break;
sl = netdev_priv(dev);
if (sl->leased) {
if (sl->line != line)
continue;
if (sl->tty)
return NULL;
/* Clear ESCAPE & ERROR flags */
sl->flags &= (1 << SLF_INUSE);
return sl;
}
if (sl->tty)
continue;
if (current->pid == sl->pid) {
if (sl->line == line && score < 3) {
sel = i;
score = 3;
continue;
}
if (score < 2) {
sel = i;
score = 2;
}
continue;
}
if (sl->line == line && score < 1) {
sel = i;
score = 1;
continue;
}
if (score < 0) {
sel = i;
score = 0;
}
}
if (sel >= 0) {
i = sel;
dev = slip_devs[i];
if (score > 1) {
sl = netdev_priv(dev);
sl->flags &= (1 << SLF_INUSE);
return sl;
}
}
/* Sorry, too many, all slots in use */
if (i >= slip_maxdev)
return NULL;
if (dev) {
sl = netdev_priv(dev);
if (test_bit(SLF_INUSE, &sl->flags)) {
unregister_netdevice(dev);
dev = NULL;
slip_devs[i] = NULL;
}
}
if (!dev) {
char name[IFNAMSIZ];
sprintf(name, "sl%d", i);
dev = alloc_netdev(sizeof(*sl), name, sl_setup);
if (!dev)
return NULL;
dev->base_addr = i;
}
sl = netdev_priv(dev);
/* Initialize channel control data */
sl->magic = SLIP_MAGIC;
sl->dev = dev;
spin_lock_init(&sl->lock);
sl->mode = SL_MODE_DEFAULT;
#ifdef CONFIG_SLIP_SMART
init_timer(&sl->keepalive_timer); /* initialize timer_list struct */
sl->keepalive_timer.data=(unsigned long)sl;
sl->keepalive_timer.function=sl_keepalive;
init_timer(&sl->outfill_timer);
sl->outfill_timer.data=(unsigned long)sl;
sl->outfill_timer.function=sl_outfill;
#endif
slip_devs[i] = dev;
return sl;
}
/*
* Open the high-level part of the SLIP channel.
* This function is called by the TTY module when the
* SLIP line discipline is called for. Because we are
* sure the tty line exists, we only have to link it to
* a free SLIP channel...
*
* Called in process context serialized from other ldisc calls.
*/
static int slip_open(struct tty_struct *tty)
{
struct slip *sl;
int err;
if(!capable(CAP_NET_ADMIN))
return -EPERM;
/* RTnetlink lock is misused here to serialize concurrent
opens of slip channels. There are better ways, but it is
the simplest one.
*/
rtnl_lock();
/* Collect hanged up channels. */
sl_sync();
sl = (struct slip *) tty->disc_data;
err = -EEXIST;
/* First make sure we're not already connected. */
if (sl && sl->magic == SLIP_MAGIC)
goto err_exit;
/* OK. Find a free SLIP channel to use. */
err = -ENFILE;
if ((sl = sl_alloc(tty_devnum(tty))) == NULL)
goto err_exit;
sl->tty = tty;
tty->disc_data = sl;
sl->line = tty_devnum(tty);
sl->pid = current->pid;
/* FIXME: already done before we were called - seems this can go */
if (tty->driver->flush_buffer)
tty->driver->flush_buffer(tty);
if (!test_bit(SLF_INUSE, &sl->flags)) {
/* Perform the low-level SLIP initialization. */
if ((err = sl_alloc_bufs(sl, SL_MTU)) != 0)
goto err_free_chan;
set_bit(SLF_INUSE, &sl->flags);
if ((err = register_netdevice(sl->dev)))
goto err_free_bufs;
}
#ifdef CONFIG_SLIP_SMART
if (sl->keepalive) {
sl->keepalive_timer.expires=jiffies+sl->keepalive*HZ;
add_timer (&sl->keepalive_timer);
}
if (sl->outfill) {
sl->outfill_timer.expires=jiffies+sl->outfill*HZ;
add_timer (&sl->outfill_timer);
}
#endif
/* Done. We have linked the TTY line to a channel. */
rtnl_unlock();
return sl->dev->base_addr;
err_free_bufs:
sl_free_bufs(sl);
err_free_chan:
sl->tty = NULL;
tty->disc_data = NULL;
clear_bit(SLF_INUSE, &sl->flags);
err_exit:
rtnl_unlock();
/* Count references from TTY module */
return err;
}
/*
FIXME: 1,2 are fixed 3 was never true anyway.
Let me to blame a bit.
1. TTY module calls this funstion on soft interrupt.
2. TTY module calls this function WITH MASKED INTERRUPTS!
3. TTY module does not notify us about line discipline
shutdown,
Seems, now it is clean. The solution is to consider netdevice and
line discipline sides as two independent threads.
By-product (not desired): sl? does not feel hangups and remains open.
It is supposed, that user level program (dip, diald, slattach...)
will catch SIGHUP and make the rest of work.
I see no way to make more with current tty code. --ANK
*/
/*
* Close down a SLIP channel.
* This means flushing out any pending queues, and then returning. This
* call is serialized against other ldisc functions.
*/
static void
slip_close(struct tty_struct *tty)
{
struct slip *sl = (struct slip *) tty->disc_data;
/* First make sure we're connected. */
if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
return;
tty->disc_data = NULL;
sl->tty = NULL;
if (!sl->leased)
sl->line = 0;
/* VSV = very important to remove timers */
#ifdef CONFIG_SLIP_SMART
del_timer_sync(&sl->keepalive_timer);
del_timer_sync(&sl->outfill_timer);
#endif
/* Count references from TTY module */
}
/************************************************************************
* STANDARD SLIP ENCAPSULATION *
************************************************************************/
int
slip_esc(unsigned char *s, unsigned char *d, int len)
{
unsigned char *ptr = d;
unsigned char c;
/*
* Send an initial END character to flush out any
* data that may have accumulated in the receiver
* due to line noise.
*/
*ptr++ = END;
/*
* For each byte in the packet, send the appropriate
* character sequence, according to the SLIP protocol.
*/
while (len-- > 0) {
switch(c = *s++) {
case END:
*ptr++ = ESC;
*ptr++ = ESC_END;
break;
case ESC:
*ptr++ = ESC;
*ptr++ = ESC_ESC;
break;
default:
*ptr++ = c;
break;