linux/drivers/net/hamradio/mkiss.c

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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, see <http://www.gnu.org/licenses/>.
*
* 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/module.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 cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 08:04:11 +00:00
#include <linux/slab.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 <linux/compat.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 */
/* 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->dev->stats.rx_errors++;
spin_unlock_bh(&ax->buflock);
return;
}
if (ax->crcmode != CRC_MODE_SMACK && ax->crcauto) {
printk(KERN_INFO
"mkiss: %s: Switching 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->dev->stats.rx_errors++;
spin_unlock_bh(&ax->buflock);
return;
}
if (ax->crcmode != CRC_MODE_FLEX && ax->crcauto) {
printk(KERN_INFO
"mkiss: %s: Switching 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;
}
}
count = ax->rcount;
if ((skb = dev_alloc_skb(count)) == NULL) {
printk(KERN_ERR "mkiss: %s: memory squeeze, dropping packet.\n",
ax->dev->name);
ax->dev->stats.rx_dropped++;
spin_unlock_bh(&ax->buflock);
return;
}
memcpy(skb_put(skb,count), ax->rbuff, count);
skb->protocol = ax25_type_trans(skb, ax->dev);
netif_rx(skb);
ax->dev->stats.rx_packets++;
ax->dev->stats.rx_bytes += count;
spin_unlock_bh(&ax->buflock);
}
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->dev->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;
[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>
2006-06-09 19:20:56 +00:00
netif_tx_lock_bh(dev);
netif_addr_lock(dev);
memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
netif_addr_unlock(dev);
[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>
2006-06-09 19:20:56 +00:00
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;
dev->stats.tx_dropped++;
}
}
ax->xhead = ax->xbuff;
if (ax->rcount) {
if (ax->rcount <= len) {
memcpy(ax->rbuff, orbuff, ax->rcount);
} else {
ax->rcount = 0;
dev->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);
dev->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, 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, 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, ax->xbuff, crc, len+2);
break;
default:
count = kiss_esc(p, ax->xbuff, len);
}
}
spin_unlock_bh(&ax->buflock);
set_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags);
actual = ax->tty->ops->write(ax->tty, ax->xbuff, count);
dev->stats.tx_packets++;
dev->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 netdev_tx_t ax_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct mkiss *ax = netdev_priv(dev);
if (skb->protocol == htons(ETH_P_IP))
return ax25_ip_xmit(skb);
if (!netif_running(dev)) {
printk(KERN_ERR "mkiss: %s: xmit call when iface is down\n", dev->name);
return NETDEV_TX_BUSY;
}
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 NETDEV_TX_BUSY;
}
printk(KERN_ERR "mkiss: %s: transmit timed out, %s?\n", dev->name,
(tty_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... :-) */
netif_stop_queue(dev);
ax_encaps(dev, skb->data, skb->len);
kfree_skb(skb);
return NETDEV_TX_OK;
}
static int ax_open_dev(struct net_device *dev)
{
struct mkiss *ax = netdev_priv(dev);
if (ax->tty == NULL)
return -ENODEV;
return 0;
}
/* 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 const struct net_device_ops ax_netdev_ops = {
.ndo_open = ax_open_dev,
.ndo_stop = ax_close,
.ndo_start_xmit = ax_xmit,
.ndo_set_mac_address = ax_set_mac_address,
};
static void ax_setup(struct net_device *dev)
{
/* Finish setting up the DEVICE info. */
dev->mtu = AX_MTU;
dev->hard_header_len = 0;
dev->addr_len = 0;
dev->type = ARPHRD_AX25;
dev->tx_queue_len = 10;
dev->header_ops = &ax25_header_ops;
dev->netdev_ops = &ax_netdev_ops;
memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
memcpy(dev->dev_addr, &ax25_defaddr, 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;
if (tty->ops->write == NULL)
return -EOPNOTSUPP;
dev = alloc_netdev(sizeof(struct mkiss), "ax%d", NET_NAME_UNKNOWN,
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);
sema_init(&ax->dead_sem, 0);
ax->tty = tty;
tty->disc_data = ax;
[PATCH] TTY layer buffering revamp The API and code have been through various bits of initial review by serial driver people but they definitely need to live somewhere for a while so the unconverted drivers can get knocked into shape, existing drivers that have been updated can be better tuned and bugs whacked out. This replaces the tty flip buffers with kmalloc objects in rings. In the normal situation for an IRQ driven serial port at typical speeds the behaviour is pretty much the same, two buffers end up allocated and the kernel cycles between them as before. When there are delays or at high speed we now behave far better as the buffer pool can grow a bit rather than lose characters. This also means that we can operate at higher speeds reliably. For drivers that receive characters in blocks (DMA based, USB and especially virtualisation) the layer allows a lot of driver specific code that works around the tty layer with private secondary queues to be removed. The IBM folks need this sort of layer, the smart serial port people do, the virtualisers do (because a virtualised tty typically operates at infinite speed rather than emulating 9600 baud). Finally many drivers had invalid and unsafe attempts to avoid buffer overflows by directly invoking tty methods extracted out of the innards of work queue structs. These are no longer needed and all go away. That fixes various random hangs with serial ports on overflow. The other change in here is to optimise the receive_room path that is used by some callers. It turns out that only one ldisc uses receive room except asa constant and it updates it far far less than the value is read. We thus make it a variable not a function call. I expect the code to contain bugs due to the size alone but I'll be watching and squashing them and feeding out new patches as it goes. Because the buffers now dynamically expand you should only run out of buffering when the kernel runs out of memory for real. That means a lot of the horrible hacks high performance drivers used to do just aren't needed any more. Description: tty_insert_flip_char is an old API and continues to work as before, as does tty_flip_buffer_push() [this is why many drivers dont need modification]. It does now also return the number of chars inserted There are also tty_buffer_request_room(tty, len) which asks for a buffer block of the length requested and returns the space found. This improves efficiency with hardware that knows how much to transfer. and tty_insert_flip_string_flags(tty, str, flags, len) to insert a string of characters and flags For a smart interface the usual code is len = tty_request_buffer_room(tty, amount_hardware_says); tty_insert_flip_string(tty, buffer_from_card, len); More description! At the moment tty buffers are attached directly to the tty. This is causing a lot of the problems related to tty layer locking, also problems at high speed and also with bursty data (such as occurs in virtualised environments) I'm working on ripping out the flip buffers and replacing them with a pool of dynamically allocated buffers. This allows both for old style "byte I/O" devices and also helps virtualisation and smart devices where large blocks of data suddenely materialise and need storing. So far so good. Lots of drivers reference tty->flip.*. Several of them also call directly and unsafely into function pointers it provides. This will all break. Most drivers can use tty_insert_flip_char which can be kept as an API but others need more. At the moment I've added the following interfaces, if people think more will be needed now is a good time to say int tty_buffer_request_room(tty, size) Try and ensure at least size bytes are available, returns actual room (may be zero). At the moment it just uses the flipbuf space but that will change. Repeated calls without characters being added are not cumulative. (ie if you call it with 1, 1, 1, and then 4 you'll have four characters of space. The other functions will also try and grow buffers in future but this will be a more efficient way when you know block sizes. int tty_insert_flip_char(tty, ch, flag) As before insert a character if there is room. Now returns 1 for success, 0 for failure. int tty_insert_flip_string(tty, str, len) Insert a block of non error characters. Returns the number inserted. int tty_prepare_flip_string(tty, strptr, len) Adjust the buffer to allow len characters to be added. Returns a buffer pointer in strptr and the length available. This allows for hardware that needs to use functions like insl or mencpy_fromio. Signed-off-by: Alan Cox <alan@redhat.com> Cc: Paul Fulghum <paulkf@microgate.com> Signed-off-by: Hirokazu Takata <takata@linux-m32r.org> Signed-off-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: John Hawkes <hawkes@sgi.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-10 04:54:13 +00:00
tty->receive_room = 65535;
tty_driver_flush_buffer(tty);
/* Restore default settings */
dev->type = ARPHRD_AX25;
/* Perform the low-level AX25 initialization. */
err = ax_open(ax->dev);
if (err)
goto out_free_netdev;
err = register_netdev(dev);
if (err)
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_bh(&disc_data_lock);
ax = tty->disc_data;
tty->disc_data = NULL;
write_unlock_bh(&disc_data_lock);
if (!ax)
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);
/*
* Halt the transmit queue so that a new transmit cannot scribble
* on our buffers
*/
netif_stop_queue(ax->dev);
/* Free all AX25 frame buffers. */
kfree(ax->rbuff);
kfree(ax->xbuff);
ax->tty = NULL;
unregister_netdev(ax->dev);
}
/* 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;
unsigned int tmp, err;
/* First make sure we're connected. */
if (ax == NULL)
return -ENXIO;
dev = ax->dev;
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;
}
[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>
2006-06-09 19:20:56 +00:00
netif_tx_lock_bh(dev);
memcpy(dev->dev_addr, addr, AX25_ADDR_LEN);
[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>
2006-06-09 19:20:56 +00:00
netif_tx_unlock_bh(dev);
err = 0;
break;
}
default:
err = -ENOIOCTLCMD;
}
mkiss_put(ax);
return err;
}
#ifdef CONFIG_COMPAT
static long mkiss_compat_ioctl(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg)
{
switch (cmd) {
case SIOCGIFNAME:
case SIOCGIFENCAP:
case SIOCSIFENCAP:
case SIOCSIFHWADDR:
return mkiss_ioctl(tty, file, cmd,
(unsigned long)compat_ptr(arg));
}
return -ENOIOCTLCMD;
}
#endif
/*
* 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.
*/
Revert "tty: make receive_buf() return the amout of bytes received" This reverts commit b1c43f82c5aa265442f82dba31ce985ebb7aa71c. It was broken in so many ways, and results in random odd pty issues. It re-introduced the buggy schedule_work() in flush_to_ldisc() that can cause endless work-loops (see commit a5660b41af6a: "tty: fix endless work loop when the buffer fills up"). It also used an "unsigned int" return value fo the ->receive_buf() function, but then made multiple functions return a negative error code, and didn't actually check for the error in the caller. And it didn't actually work at all. BenH bisected down odd tty behavior to it: "It looks like the patch is causing some major malfunctions of the X server for me, possibly related to PTYs. For example, cat'ing a large file in a gnome terminal hangs the kernel for -minutes- in a loop of what looks like flush_to_ldisc/workqueue code, (some ftrace data in the quoted bits further down). ... Some more data: It -looks- like what happens is that the flush_to_ldisc work queue entry constantly re-queues itself (because the PTY is full ?) and the workqueue thread will basically loop forver calling it without ever scheduling, thus starving the consumer process that could have emptied the PTY." which is pretty much exactly the problem we fixed in a5660b41af6a. Milton Miller pointed out the 'unsigned int' issue. Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reported-by: Milton Miller <miltonm@bga.com> Cc: Stefan Bigler <stefan.bigler@keymile.com> Cc: Toby Gray <toby.gray@realvnc.com> Cc: Felipe Balbi <balbi@ti.com> Cc: Greg Kroah-Hartman <gregkh@suse.de> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-06-03 21:33:24 +00:00
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)
Revert "tty: make receive_buf() return the amout of bytes received" This reverts commit b1c43f82c5aa265442f82dba31ce985ebb7aa71c. It was broken in so many ways, and results in random odd pty issues. It re-introduced the buggy schedule_work() in flush_to_ldisc() that can cause endless work-loops (see commit a5660b41af6a: "tty: fix endless work loop when the buffer fills up"). It also used an "unsigned int" return value fo the ->receive_buf() function, but then made multiple functions return a negative error code, and didn't actually check for the error in the caller. And it didn't actually work at all. BenH bisected down odd tty behavior to it: "It looks like the patch is causing some major malfunctions of the X server for me, possibly related to PTYs. For example, cat'ing a large file in a gnome terminal hangs the kernel for -minutes- in a loop of what looks like flush_to_ldisc/workqueue code, (some ftrace data in the quoted bits further down). ... Some more data: It -looks- like what happens is that the flush_to_ldisc work queue entry constantly re-queues itself (because the PTY is full ?) and the workqueue thread will basically loop forver calling it without ever scheduling, thus starving the consumer process that could have emptied the PTY." which is pretty much exactly the problem we fixed in a5660b41af6a. Milton Miller pointed out the 'unsigned int' issue. Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reported-by: Milton Miller <miltonm@bga.com> Cc: Stefan Bigler <stefan.bigler@keymile.com> Cc: Toby Gray <toby.gray@realvnc.com> Cc: Felipe Balbi <balbi@ti.com> Cc: Greg Kroah-Hartman <gregkh@suse.de> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-06-03 21:33:24 +00:00
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 */
Revert "tty: make receive_buf() return the amout of bytes received" This reverts commit b1c43f82c5aa265442f82dba31ce985ebb7aa71c. It was broken in so many ways, and results in random odd pty issues. It re-introduced the buggy schedule_work() in flush_to_ldisc() that can cause endless work-loops (see commit a5660b41af6a: "tty: fix endless work loop when the buffer fills up"). It also used an "unsigned int" return value fo the ->receive_buf() function, but then made multiple functions return a negative error code, and didn't actually check for the error in the caller. And it didn't actually work at all. BenH bisected down odd tty behavior to it: "It looks like the patch is causing some major malfunctions of the X server for me, possibly related to PTYs. For example, cat'ing a large file in a gnome terminal hangs the kernel for -minutes- in a loop of what looks like flush_to_ldisc/workqueue code, (some ftrace data in the quoted bits further down). ... Some more data: It -looks- like what happens is that the flush_to_ldisc work queue entry constantly re-queues itself (because the PTY is full ?) and the workqueue thread will basically loop forver calling it without ever scheduling, thus starving the consumer process that could have emptied the PTY." which is pretty much exactly the problem we fixed in a5660b41af6a. Milton Miller pointed out the 'unsigned int' issue. Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reported-by: Milton Miller <miltonm@bga.com> Cc: Stefan Bigler <stefan.bigler@keymile.com> Cc: Toby Gray <toby.gray@realvnc.com> Cc: Felipe Balbi <balbi@ti.com> Cc: Greg Kroah-Hartman <gregkh@suse.de> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-06-03 21:33:24 +00:00
while (count--) {
if (fp != NULL && *fp++) {
if (!test_and_set_bit(AXF_ERROR, &ax->flags))
ax->dev->stats.rx_errors++;
cp++;
continue;
}
kiss_unesc(ax, *cp++);
}
mkiss_put(ax);
tty_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->ops->write(tty, ax->xhead, ax->xleft);
ax->xleft -= actual;
ax->xhead += actual;
out:
mkiss_put(ax);
}
static struct tty_ldisc_ops ax_ldisc = {
.owner = THIS_MODULE,
.magic = TTY_LDISC_MAGIC,
.name = "mkiss",
.open = mkiss_open,
.close = mkiss_close,
.ioctl = mkiss_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = mkiss_compat_ioctl,
#endif
.receive_buf = mkiss_receive_buf,
.write_wakeup = mkiss_write_wakeup
};
static const char banner[] __initconst = KERN_INFO \
"mkiss: AX.25 Multikiss, Hans Albas PE1AYX\n";
static const char msg_regfail[] __initconst = KERN_ERR \
"mkiss: can't register line discipline (err = %d)\n";
static int __init mkiss_init_driver(void)
{
int status;
printk(banner);
status = tty_register_ldisc(N_AX25, &ax_ldisc);
if (status != 0)
printk(msg_regfail, status);
return status;
}
static const char msg_unregfail[] = 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);