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linux_dsm_epyc7002/drivers/net/hamradio/mkiss.c
Herbert Xu 932ff279a4 [NET]: Add netif_tx_lock 
Various drivers use xmit_lock internally to synchronise with their
transmission routines.  They do so without setting xmit_lock_owner.
This is fine as long as netpoll is not in use.

With netpoll it is possible for deadlocks to occur if xmit_lock_owner
isn't set.  This is because if a printk occurs while xmit_lock is held
and xmit_lock_owner is not set can cause netpoll to attempt to take
xmit_lock recursively.

While it is possible to resolve this by getting netpoll to use
trylock, it is suboptimal because netpoll's sole objective is to
maximise the chance of getting the printk out on the wire.  So
delaying or dropping the message is to be avoided as much as possible.

So the only alternative is to always set xmit_lock_owner.  The
following patch does this by introducing the netif_tx_lock family of
functions that take care of setting/unsetting xmit_lock_owner.

I renamed xmit_lock to _xmit_lock to indicate that it should not be
used directly.  I didn't provide irq versions of the netif_tx_lock
functions since xmit_lock is meant to be a BH-disabling lock.

This is pretty much a straight text substitution except for a small
bug fix in winbond.  It currently uses
netif_stop_queue/spin_unlock_wait to stop transmission.  This is
unsafe as an IRQ can potentially wake up the queue.  So it is safer to
use netif_tx_disable.

The hamradio bits used spin_lock_irq but it is unnecessary as
xmit_lock must never be taken in an IRQ handler.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-06-17 21:30:14 -07:00

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/*
* This program is free software; you can distribute it and/or modify it
* under the terms of the GNU General Public License (Version 2) as
* published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
*
* Copyright (C) Hans Alblas PE1AYX <hans@esrac.ele.tue.nl>
* Copyright (C) 2004, 05 Ralf Baechle DL5RB <ralf@linux-mips.org>
* Copyright (C) 2004, 05 Thomas Osterried DL9SAU <thomas@x-berg.in-berlin.de>
*/
#include <linux/config.h>
#include <linux/module.h>
#include <asm/system.h>
#include <linux/bitops.h>
#include <asm/uaccess.h>
#include <linux/crc16.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/tty.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/major.h>
#include <linux/init.h>
#include <linux/rtnetlink.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/jiffies.h>
#include <net/ax25.h>
#define AX_MTU 236
/* SLIP/KISS protocol characters. */
#define END 0300 /* indicates end of frame */
#define ESC 0333 /* indicates byte stuffing */
#define ESC_END 0334 /* ESC ESC_END means END 'data' */
#define ESC_ESC 0335 /* ESC ESC_ESC means ESC 'data' */
struct mkiss {
struct tty_struct *tty; /* ptr to TTY structure */
struct net_device *dev; /* easy for intr handling */
/* These are pointers to the malloc()ed frame buffers. */
spinlock_t buflock;/* lock for rbuf and xbuf */
unsigned char *rbuff; /* receiver buffer */
int rcount; /* received chars counter */
unsigned char *xbuff; /* transmitter buffer */
unsigned char *xhead; /* pointer to next byte to XMIT */
int xleft; /* bytes left in XMIT queue */
struct net_device_stats stats;
/* Detailed SLIP statistics. */
int mtu; /* Our mtu (to spot changes!) */
int buffsize; /* Max buffers sizes */
unsigned long flags; /* Flag values/ mode etc */
/* long req'd: used by set_bit --RR */
#define AXF_INUSE 0 /* Channel in use */
#define AXF_ESCAPE 1 /* ESC received */
#define AXF_ERROR 2 /* Parity, etc. error */
#define AXF_KEEPTEST 3 /* Keepalive test flag */
#define AXF_OUTWAIT 4 /* is outpacket was flag */
int mode;
int crcmode; /* MW: for FlexNet, SMACK etc. */
int crcauto; /* CRC auto mode */
#define CRC_MODE_NONE 0
#define CRC_MODE_FLEX 1
#define CRC_MODE_SMACK 2
#define CRC_MODE_FLEX_TEST 3
#define CRC_MODE_SMACK_TEST 4
atomic_t refcnt;
struct semaphore dead_sem;
};
/*---------------------------------------------------------------------------*/
static const unsigned short crc_flex_table[] = {
0x0f87, 0x1e0e, 0x2c95, 0x3d1c, 0x49a3, 0x582a, 0x6ab1, 0x7b38,
0x83cf, 0x9246, 0xa0dd, 0xb154, 0xc5eb, 0xd462, 0xe6f9, 0xf770,
0x1f06, 0x0e8f, 0x3c14, 0x2d9d, 0x5922, 0x48ab, 0x7a30, 0x6bb9,
0x934e, 0x82c7, 0xb05c, 0xa1d5, 0xd56a, 0xc4e3, 0xf678, 0xe7f1,
0x2e85, 0x3f0c, 0x0d97, 0x1c1e, 0x68a1, 0x7928, 0x4bb3, 0x5a3a,
0xa2cd, 0xb344, 0x81df, 0x9056, 0xe4e9, 0xf560, 0xc7fb, 0xd672,
0x3e04, 0x2f8d, 0x1d16, 0x0c9f, 0x7820, 0x69a9, 0x5b32, 0x4abb,
0xb24c, 0xa3c5, 0x915e, 0x80d7, 0xf468, 0xe5e1, 0xd77a, 0xc6f3,
0x4d83, 0x5c0a, 0x6e91, 0x7f18, 0x0ba7, 0x1a2e, 0x28b5, 0x393c,
0xc1cb, 0xd042, 0xe2d9, 0xf350, 0x87ef, 0x9666, 0xa4fd, 0xb574,
0x5d02, 0x4c8b, 0x7e10, 0x6f99, 0x1b26, 0x0aaf, 0x3834, 0x29bd,
0xd14a, 0xc0c3, 0xf258, 0xe3d1, 0x976e, 0x86e7, 0xb47c, 0xa5f5,
0x6c81, 0x7d08, 0x4f93, 0x5e1a, 0x2aa5, 0x3b2c, 0x09b7, 0x183e,
0xe0c9, 0xf140, 0xc3db, 0xd252, 0xa6ed, 0xb764, 0x85ff, 0x9476,
0x7c00, 0x6d89, 0x5f12, 0x4e9b, 0x3a24, 0x2bad, 0x1936, 0x08bf,
0xf048, 0xe1c1, 0xd35a, 0xc2d3, 0xb66c, 0xa7e5, 0x957e, 0x84f7,
0x8b8f, 0x9a06, 0xa89d, 0xb914, 0xcdab, 0xdc22, 0xeeb9, 0xff30,
0x07c7, 0x164e, 0x24d5, 0x355c, 0x41e3, 0x506a, 0x62f1, 0x7378,
0x9b0e, 0x8a87, 0xb81c, 0xa995, 0xdd2a, 0xcca3, 0xfe38, 0xefb1,
0x1746, 0x06cf, 0x3454, 0x25dd, 0x5162, 0x40eb, 0x7270, 0x63f9,
0xaa8d, 0xbb04, 0x899f, 0x9816, 0xeca9, 0xfd20, 0xcfbb, 0xde32,
0x26c5, 0x374c, 0x05d7, 0x145e, 0x60e1, 0x7168, 0x43f3, 0x527a,
0xba0c, 0xab85, 0x991e, 0x8897, 0xfc28, 0xeda1, 0xdf3a, 0xceb3,
0x3644, 0x27cd, 0x1556, 0x04df, 0x7060, 0x61e9, 0x5372, 0x42fb,
0xc98b, 0xd802, 0xea99, 0xfb10, 0x8faf, 0x9e26, 0xacbd, 0xbd34,
0x45c3, 0x544a, 0x66d1, 0x7758, 0x03e7, 0x126e, 0x20f5, 0x317c,
0xd90a, 0xc883, 0xfa18, 0xeb91, 0x9f2e, 0x8ea7, 0xbc3c, 0xadb5,
0x5542, 0x44cb, 0x7650, 0x67d9, 0x1366, 0x02ef, 0x3074, 0x21fd,
0xe889, 0xf900, 0xcb9b, 0xda12, 0xaead, 0xbf24, 0x8dbf, 0x9c36,
0x64c1, 0x7548, 0x47d3, 0x565a, 0x22e5, 0x336c, 0x01f7, 0x107e,
0xf808, 0xe981, 0xdb1a, 0xca93, 0xbe2c, 0xafa5, 0x9d3e, 0x8cb7,
0x7440, 0x65c9, 0x5752, 0x46db, 0x3264, 0x23ed, 0x1176, 0x00ff
};
static unsigned short calc_crc_flex(unsigned char *cp, int size)
{
unsigned short crc = 0xffff;
while (size--)
crc = (crc << 8) ^ crc_flex_table[((crc >> 8) ^ *cp++) & 0xff];
return crc;
}
static int check_crc_flex(unsigned char *cp, int size)
{
unsigned short crc = 0xffff;
if (size < 3)
return -1;
while (size--)
crc = (crc << 8) ^ crc_flex_table[((crc >> 8) ^ *cp++) & 0xff];
if ((crc & 0xffff) != 0x7070)
return -1;
return 0;
}
static int check_crc_16(unsigned char *cp, int size)
{
unsigned short crc = 0x0000;
if (size < 3)
return -1;
crc = crc16(0, cp, size);
if (crc != 0x0000)
return -1;
return 0;
}
/*
* Standard encapsulation
*/
static int kiss_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;
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;
}
}
*ptr++ = END;
return ptr - d;
}
/*
* MW:
* OK its ugly, but tell me a better solution without copying the
* packet to a temporary buffer :-)
*/
static int kiss_esc_crc(unsigned char *s, unsigned char *d, unsigned short crc,
int len)
{
unsigned char *ptr = d;
unsigned char c=0;
*ptr++ = END;
while (len > 0) {
if (len > 2)
c = *s++;
else if (len > 1)
c = crc >> 8;
else if (len > 0)
c = crc & 0xff;
len--;
switch (c) {
case END:
*ptr++ = ESC;
*ptr++ = ESC_END;
break;
case ESC:
*ptr++ = ESC;
*ptr++ = ESC_ESC;
break;
default:
*ptr++ = c;
break;
}
}
*ptr++ = END;
return ptr - d;
}
/* Send one completely decapsulated AX.25 packet to the AX.25 layer. */
static void ax_bump(struct mkiss *ax)
{
struct sk_buff *skb;
int count;
spin_lock_bh(&ax->buflock);
if (ax->rbuff[0] > 0x0f) {
if (ax->rbuff[0] & 0x80) {
if (check_crc_16(ax->rbuff, ax->rcount) < 0) {
ax->stats.rx_errors++;
spin_unlock_bh(&ax->buflock);
return;
}
if (ax->crcmode != CRC_MODE_SMACK && ax->crcauto) {
printk(KERN_INFO
"mkiss: %s: Switchting to crc-smack\n",
ax->dev->name);
ax->crcmode = CRC_MODE_SMACK;
}
ax->rcount -= 2;
*ax->rbuff &= ~0x80;
} else if (ax->rbuff[0] & 0x20) {
if (check_crc_flex(ax->rbuff, ax->rcount) < 0) {
ax->stats.rx_errors++;
spin_unlock_bh(&ax->buflock);
return;
}
if (ax->crcmode != CRC_MODE_FLEX && ax->crcauto) {
printk(KERN_INFO
"mkiss: %s: Switchting to crc-flexnet\n",
ax->dev->name);
ax->crcmode = CRC_MODE_FLEX;
}
ax->rcount -= 2;
/*
* dl9sau bugfix: the trailling two bytes flexnet crc
* will not be passed to the kernel. thus we have to
* correct the kissparm signature, because it indicates
* a crc but there's none
*/
*ax->rbuff &= ~0x20;
}
}
spin_unlock_bh(&ax->buflock);
count = ax->rcount;
if ((skb = dev_alloc_skb(count)) == NULL) {
printk(KERN_ERR "mkiss: %s: memory squeeze, dropping packet.\n",
ax->dev->name);
ax->stats.rx_dropped++;
return;
}
spin_lock_bh(&ax->buflock);
memcpy(skb_put(skb,count), ax->rbuff, count);
spin_unlock_bh(&ax->buflock);
skb->protocol = ax25_type_trans(skb, ax->dev);
netif_rx(skb);
ax->dev->last_rx = jiffies;
ax->stats.rx_packets++;
ax->stats.rx_bytes += count;
}
static void kiss_unesc(struct mkiss *ax, unsigned char s)
{
switch (s) {
case END:
/* drop keeptest bit = VSV */
if (test_bit(AXF_KEEPTEST, &ax->flags))
clear_bit(AXF_KEEPTEST, &ax->flags);
if (!test_and_clear_bit(AXF_ERROR, &ax->flags) && (ax->rcount > 2))
ax_bump(ax);
clear_bit(AXF_ESCAPE, &ax->flags);
ax->rcount = 0;
return;
case ESC:
set_bit(AXF_ESCAPE, &ax->flags);
return;
case ESC_ESC:
if (test_and_clear_bit(AXF_ESCAPE, &ax->flags))
s = ESC;
break;
case ESC_END:
if (test_and_clear_bit(AXF_ESCAPE, &ax->flags))
s = END;
break;
}
spin_lock_bh(&ax->buflock);
if (!test_bit(AXF_ERROR, &ax->flags)) {
if (ax->rcount < ax->buffsize) {
ax->rbuff[ax->rcount++] = s;
spin_unlock_bh(&ax->buflock);
return;
}
ax->stats.rx_over_errors++;
set_bit(AXF_ERROR, &ax->flags);
}
spin_unlock_bh(&ax->buflock);
}
static int ax_set_mac_address(struct net_device *dev, void *addr)
{
struct sockaddr_ax25 *sa = addr;
netif_tx_lock_bh(dev);
memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
netif_tx_unlock_bh(dev);
return 0;
}
/*---------------------------------------------------------------------------*/
static void ax_changedmtu(struct mkiss *ax)
{
struct net_device *dev = ax->dev;
unsigned char *xbuff, *rbuff, *oxbuff, *orbuff;
int len;
len = dev->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 = kmalloc(len + 4, GFP_ATOMIC);
rbuff = kmalloc(len + 4, GFP_ATOMIC);
if (xbuff == NULL || rbuff == NULL) {
printk(KERN_ERR "mkiss: %s: unable to grow ax25 buffers, "
"MTU change cancelled.\n",
ax->dev->name);
dev->mtu = ax->mtu;
kfree(xbuff);
kfree(rbuff);
return;
}
spin_lock_bh(&ax->buflock);
oxbuff = ax->xbuff;
ax->xbuff = xbuff;
orbuff = ax->rbuff;
ax->rbuff = rbuff;
if (ax->xleft) {
if (ax->xleft <= len) {
memcpy(ax->xbuff, ax->xhead, ax->xleft);
} else {
ax->xleft = 0;
ax->stats.tx_dropped++;
}
}
ax->xhead = ax->xbuff;
if (ax->rcount) {
if (ax->rcount <= len) {
memcpy(ax->rbuff, orbuff, ax->rcount);
} else {
ax->rcount = 0;
ax->stats.rx_over_errors++;
set_bit(AXF_ERROR, &ax->flags);
}
}
ax->mtu = dev->mtu + 73;
ax->buffsize = len;
spin_unlock_bh(&ax->buflock);
kfree(oxbuff);
kfree(orbuff);
}
/* Encapsulate one AX.25 packet and stuff into a TTY queue. */
static void ax_encaps(struct net_device *dev, unsigned char *icp, int len)
{
struct mkiss *ax = netdev_priv(dev);
unsigned char *p;
int actual, count;
if (ax->mtu != ax->dev->mtu + 73) /* Someone has been ifconfigging */
ax_changedmtu(ax);
if (len > ax->mtu) { /* Sigh, shouldn't occur BUT ... */
len = ax->mtu;
printk(KERN_ERR "mkiss: %s: truncating oversized transmit packet!\n", ax->dev->name);
ax->stats.tx_dropped++;
netif_start_queue(dev);
return;
}
p = icp;
spin_lock_bh(&ax->buflock);
if ((*p & 0x0f) != 0) {
/* Configuration Command (kissparms(1).
* Protocol spec says: never append CRC.
* This fixes a very old bug in the linux
* kiss driver. -- dl9sau */
switch (*p & 0xff) {
case 0x85:
/* command from userspace especially for us,
* not for delivery to the tnc */
if (len > 1) {
int cmd = (p[1] & 0xff);
switch(cmd) {
case 3:
ax->crcmode = CRC_MODE_SMACK;
break;
case 2:
ax->crcmode = CRC_MODE_FLEX;
break;
case 1:
ax->crcmode = CRC_MODE_NONE;
break;
case 0:
default:
ax->crcmode = CRC_MODE_SMACK_TEST;
cmd = 0;
}
ax->crcauto = (cmd ? 0 : 1);
printk(KERN_INFO "mkiss: %s: crc mode %s %d\n", ax->dev->name, (len) ? "set to" : "is", cmd);
}
spin_unlock_bh(&ax->buflock);
netif_start_queue(dev);
return;
default:
count = kiss_esc(p, (unsigned char *)ax->xbuff, len);
}
} else {
unsigned short crc;
switch (ax->crcmode) {
case CRC_MODE_SMACK_TEST:
ax->crcmode = CRC_MODE_FLEX_TEST;
printk(KERN_INFO "mkiss: %s: Trying crc-smack\n", ax->dev->name);
// fall through
case CRC_MODE_SMACK:
*p |= 0x80;
crc = swab16(crc16(0, p, len));
count = kiss_esc_crc(p, (unsigned char *)ax->xbuff, crc, len+2);
break;
case CRC_MODE_FLEX_TEST:
ax->crcmode = CRC_MODE_NONE;
printk(KERN_INFO "mkiss: %s: Trying crc-flexnet\n", ax->dev->name);
// fall through
case CRC_MODE_FLEX:
*p |= 0x20;
crc = calc_crc_flex(p, len);
count = kiss_esc_crc(p, (unsigned char *)ax->xbuff, crc, len+2);
break;
default:
count = kiss_esc(p, (unsigned char *)ax->xbuff, len);
}
}
spin_unlock_bh(&ax->buflock);
set_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags);
actual = ax->tty->driver->write(ax->tty, ax->xbuff, count);
ax->stats.tx_packets++;
ax->stats.tx_bytes += actual;
ax->dev->trans_start = jiffies;
ax->xleft = count - actual;
ax->xhead = ax->xbuff + actual;
}
/* Encapsulate an AX.25 packet and kick it into a TTY queue. */
static int ax_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct mkiss *ax = netdev_priv(dev);
if (!netif_running(dev)) {
printk(KERN_ERR "mkiss: %s: xmit call when iface is down\n", dev->name);
return 1;
}
if (netif_queue_stopped(dev)) {
/*
* May be we must check transmitter timeout here ?
* 14 Oct 1994 Dmitry Gorodchanin.
*/
if (time_before(jiffies, dev->trans_start + 20 * HZ)) {
/* 20 sec timeout not reached */
return 1;
}
printk(KERN_ERR "mkiss: %s: transmit timed out, %s?\n", dev->name,
(ax->tty->driver->chars_in_buffer(ax->tty) || ax->xleft) ?
"bad line quality" : "driver error");
ax->xleft = 0;
clear_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags);
netif_start_queue(dev);
}
/* We were not busy, so we are now... :-) */
if (skb != NULL) {
netif_stop_queue(dev);
ax_encaps(dev, skb->data, skb->len);
kfree_skb(skb);
}
return 0;
}
static int ax_open_dev(struct net_device *dev)
{
struct mkiss *ax = netdev_priv(dev);
if (ax->tty == NULL)
return -ENODEV;
return 0;
}
#if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
/* Return the frame type ID */
static int ax_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
void *daddr, void *saddr, unsigned len)
{
#ifdef CONFIG_INET
if (type != htons(ETH_P_AX25))
return ax25_hard_header(skb, dev, type, daddr, saddr, len);
#endif
return 0;
}
static int ax_rebuild_header(struct sk_buff *skb)
{
#ifdef CONFIG_INET
return ax25_rebuild_header(skb);
#else
return 0;
#endif
}
#endif /* CONFIG_{AX25,AX25_MODULE} */
/* Open the low-level part of the AX25 channel. Easy! */
static int ax_open(struct net_device *dev)
{
struct mkiss *ax = netdev_priv(dev);
unsigned long len;
if (ax->tty == NULL)
return -ENODEV;
/*
* Allocate the frame buffers:
*
* rbuff Receive buffer.
* xbuff Transmit buffer.
*/
len = dev->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;
if ((ax->rbuff = kmalloc(len + 4, GFP_KERNEL)) == NULL)
goto norbuff;
if ((ax->xbuff = kmalloc(len + 4, GFP_KERNEL)) == NULL)
goto noxbuff;
ax->mtu = dev->mtu + 73;
ax->buffsize = len;
ax->rcount = 0;
ax->xleft = 0;
ax->flags &= (1 << AXF_INUSE); /* Clear ESCAPE & ERROR flags */
spin_lock_init(&ax->buflock);
return 0;
noxbuff:
kfree(ax->rbuff);
norbuff:
return -ENOMEM;
}
/* Close the low-level part of the AX25 channel. Easy! */
static int ax_close(struct net_device *dev)
{
struct mkiss *ax = netdev_priv(dev);
if (ax->tty)
clear_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags);
netif_stop_queue(dev);
return 0;
}
static struct net_device_stats *ax_get_stats(struct net_device *dev)
{
struct mkiss *ax = netdev_priv(dev);
return &ax->stats;
}
static void ax_setup(struct net_device *dev)
{
static char ax25_bcast[AX25_ADDR_LEN] =
{'Q'<<1,'S'<<1,'T'<<1,' '<<1,' '<<1,' '<<1,'0'<<1};
static char ax25_test[AX25_ADDR_LEN] =
{'L'<<1,'I'<<1,'N'<<1,'U'<<1,'X'<<1,' '<<1,'1'<<1};
/* Finish setting up the DEVICE info. */
dev->mtu = AX_MTU;
dev->hard_start_xmit = ax_xmit;
dev->open = ax_open_dev;
dev->stop = ax_close;
dev->get_stats = ax_get_stats;
dev->set_mac_address = ax_set_mac_address;
dev->hard_header_len = 0;
dev->addr_len = 0;
dev->type = ARPHRD_AX25;
dev->tx_queue_len = 10;
dev->hard_header = ax_header;
dev->rebuild_header = ax_rebuild_header;
memcpy(dev->broadcast, ax25_bcast, AX25_ADDR_LEN);
memcpy(dev->dev_addr, ax25_test, AX25_ADDR_LEN);
dev->flags = IFF_BROADCAST | IFF_MULTICAST;
}
/*
* 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
* sixpack_receive_buf while another calls sixpack_close, which zeroes
* tty->disc_data and frees the memory that sixpack_receive_buf 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.
*/
static DEFINE_RWLOCK(disc_data_lock);
static struct mkiss *mkiss_get(struct tty_struct *tty)
{
struct mkiss *ax;
read_lock(&disc_data_lock);
ax = tty->disc_data;
if (ax)
atomic_inc(&ax->refcnt);
read_unlock(&disc_data_lock);
return ax;
}
static void mkiss_put(struct mkiss *ax)
{
if (atomic_dec_and_test(&ax->refcnt))
up(&ax->dead_sem);
}
static int crc_force = 0; /* Can be overridden with insmod */
static int mkiss_open(struct tty_struct *tty)
{
struct net_device *dev;
struct mkiss *ax;
int err;
if (!capable(CAP_NET_ADMIN))
return -EPERM;
dev = alloc_netdev(sizeof(struct mkiss), "ax%d", ax_setup);
if (!dev) {
err = -ENOMEM;
goto out;
}
ax = netdev_priv(dev);
ax->dev = dev;
spin_lock_init(&ax->buflock);
atomic_set(&ax->refcnt, 1);
init_MUTEX_LOCKED(&ax->dead_sem);
ax->tty = tty;
tty->disc_data = ax;
tty->receive_room = 65535;
if (tty->driver->flush_buffer)
tty->driver->flush_buffer(tty);
/* Restore default settings */
dev->type = ARPHRD_AX25;
/* Perform the low-level AX25 initialization. */
if ((err = ax_open(ax->dev))) {
goto out_free_netdev;
}
if (register_netdev(dev))
goto out_free_buffers;
/* after register_netdev() - because else printk smashes the kernel */
switch (crc_force) {
case 3:
ax->crcmode = CRC_MODE_SMACK;
printk(KERN_INFO "mkiss: %s: crc mode smack forced.\n",
ax->dev->name);
break;
case 2:
ax->crcmode = CRC_MODE_FLEX;
printk(KERN_INFO "mkiss: %s: crc mode flexnet forced.\n",
ax->dev->name);
break;
case 1:
ax->crcmode = CRC_MODE_NONE;
printk(KERN_INFO "mkiss: %s: crc mode disabled.\n",
ax->dev->name);
break;
case 0:
/* fall through */
default:
crc_force = 0;
printk(KERN_INFO "mkiss: %s: crc mode is auto.\n",
ax->dev->name);
ax->crcmode = CRC_MODE_SMACK_TEST;
}
ax->crcauto = (crc_force ? 0 : 1);
netif_start_queue(dev);
/* Done. We have linked the TTY line to a channel. */
return 0;
out_free_buffers:
kfree(ax->rbuff);
kfree(ax->xbuff);
out_free_netdev:
free_netdev(dev);
out:
return err;
}
static void mkiss_close(struct tty_struct *tty)
{
struct mkiss *ax;
write_lock(&disc_data_lock);
ax = tty->disc_data;
tty->disc_data = NULL;
write_unlock(&disc_data_lock);
if (ax == 0)
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.
*/
if (!atomic_dec_and_test(&ax->refcnt))
down(&ax->dead_sem);
unregister_netdev(ax->dev);
/* Free all AX25 frame buffers. */
kfree(ax->rbuff);
kfree(ax->xbuff);
ax->tty = NULL;
}
/* Perform I/O control on an active ax25 channel. */
static int mkiss_ioctl(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg)
{
struct mkiss *ax = mkiss_get(tty);
struct net_device *dev = ax->dev;
unsigned int tmp, err;
/* First make sure we're connected. */
if (ax == NULL)
return -ENXIO;
switch (cmd) {
case SIOCGIFNAME:
err = copy_to_user((void __user *) arg, ax->dev->name,
strlen(ax->dev->name) + 1) ? -EFAULT : 0;
break;
case SIOCGIFENCAP:
err = put_user(4, (int __user *) arg);
break;
case SIOCSIFENCAP:
if (get_user(tmp, (int __user *) arg)) {
err = -EFAULT;
break;
}
ax->mode = tmp;
dev->addr_len = AX25_ADDR_LEN;
dev->hard_header_len = AX25_KISS_HEADER_LEN +
AX25_MAX_HEADER_LEN + 3;
dev->type = ARPHRD_AX25;
err = 0;
break;
case SIOCSIFHWADDR: {
char addr[AX25_ADDR_LEN];
if (copy_from_user(&addr,
(void __user *) arg, AX25_ADDR_LEN)) {
err = -EFAULT;
break;
}
netif_tx_lock_bh(dev);
memcpy(dev->dev_addr, addr, AX25_ADDR_LEN);
netif_tx_unlock_bh(dev);
err = 0;
break;
}
default:
err = -ENOIOCTLCMD;
}
mkiss_put(ax);
return err;
}
/*
* Handle the 'receiver data ready' interrupt.
* This function is called by the 'tty_io' module in the kernel when
* a block of data has been received, which can now be decapsulated
* and sent on to the AX.25 layer for further processing.
*/
static void mkiss_receive_buf(struct tty_struct *tty, const unsigned char *cp,
char *fp, int count)
{
struct mkiss *ax = mkiss_get(tty);
if (!ax)
return;
/*
* Argh! mtu change time! - costs us the packet part received
* at the change
*/
if (ax->mtu != ax->dev->mtu + 73)
ax_changedmtu(ax);
/* Read the characters out of the buffer */
while (count--) {
if (fp != NULL && *fp++) {
if (!test_and_set_bit(AXF_ERROR, &ax->flags))
ax->stats.rx_errors++;
cp++;
continue;
}
kiss_unesc(ax, *cp++);
}
mkiss_put(ax);
if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
&& tty->driver->unthrottle)
tty->driver->unthrottle(tty);
}
/*
* Called by the driver when there's room for more data. If we have
* more packets to send, we send them here.
*/
static void mkiss_write_wakeup(struct tty_struct *tty)
{
struct mkiss *ax = mkiss_get(tty);
int actual;
if (!ax)
return;
if (ax->xleft <= 0) {
/* Now serial buffer is almost free & we can start
* transmission of another packet
*/
clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
netif_wake_queue(ax->dev);
goto out;
}
actual = tty->driver->write(tty, ax->xhead, ax->xleft);
ax->xleft -= actual;
ax->xhead += actual;
out:
mkiss_put(ax);
}
static struct tty_ldisc ax_ldisc = {
.owner = THIS_MODULE,
.magic = TTY_LDISC_MAGIC,
.name = "mkiss",
.open = mkiss_open,
.close = mkiss_close,
.ioctl = mkiss_ioctl,
.receive_buf = mkiss_receive_buf,
.write_wakeup = mkiss_write_wakeup
};
static char banner[] __initdata = KERN_INFO \
"mkiss: AX.25 Multikiss, Hans Albas PE1AYX\n";
static char msg_regfail[] __initdata = KERN_ERR \
"mkiss: can't register line discipline (err = %d)\n";
static int __init mkiss_init_driver(void)
{
int status;
printk(banner);
if ((status = tty_register_ldisc(N_AX25, &ax_ldisc)) != 0)
printk(msg_regfail);
return status;
}
static const char msg_unregfail[] __exitdata = KERN_ERR \
"mkiss: can't unregister line discipline (err = %d)\n";
static void __exit mkiss_exit_driver(void)
{
int ret;
if ((ret = tty_unregister_ldisc(N_AX25)))
printk(msg_unregfail, ret);
}
MODULE_AUTHOR("Ralf Baechle DL5RB <ralf@linux-mips.org>");
MODULE_DESCRIPTION("KISS driver for AX.25 over TTYs");
module_param(crc_force, int, 0);
MODULE_PARM_DESC(crc_force, "crc [0 = auto | 1 = none | 2 = flexnet | 3 = smack]");
MODULE_LICENSE("GPL");
MODULE_ALIAS_LDISC(N_AX25);
module_init(mkiss_init_driver);
module_exit(mkiss_exit_driver);
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