linux/drivers/net/hamradio/6pack.c

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/*
* 6pack.c This module implements the 6pack protocol for kernel-based
* devices like TTY. It interfaces between a raw TTY and the
* kernel's AX.25 protocol layers.
*
* Authors: Andreas Könsgen <ajk@comnets.uni-bremen.de>
* Ralf Baechle DL5RB <ralf@linux-mips.org>
*
* Quite a lot of stuff "stolen" by Joerg Reuter from slip.c, written by
*
* Laurence Culhane, <loz@holmes.demon.co.uk>
* Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
*/
#include <linux/module.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/timer.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 <net/ax25.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/spinlock.h>
#include <linux/if_arp.h>
#include <linux/init.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/semaphore.h>
#include <linux/compat.h>
#include <linux/atomic.h>
#define SIXPACK_VERSION "Revision: 0.3.0"
/* sixpack priority commands */
#define SIXP_SEOF 0x40 /* start and end of a 6pack frame */
#define SIXP_TX_URUN 0x48 /* transmit overrun */
#define SIXP_RX_ORUN 0x50 /* receive overrun */
#define SIXP_RX_BUF_OVL 0x58 /* receive buffer overflow */
#define SIXP_CHKSUM 0xFF /* valid checksum of a 6pack frame */
/* masks to get certain bits out of the status bytes sent by the TNC */
#define SIXP_CMD_MASK 0xC0
#define SIXP_CHN_MASK 0x07
#define SIXP_PRIO_CMD_MASK 0x80
#define SIXP_STD_CMD_MASK 0x40
#define SIXP_PRIO_DATA_MASK 0x38
#define SIXP_TX_MASK 0x20
#define SIXP_RX_MASK 0x10
#define SIXP_RX_DCD_MASK 0x18
#define SIXP_LEDS_ON 0x78
#define SIXP_LEDS_OFF 0x60
#define SIXP_CON 0x08
#define SIXP_STA 0x10
#define SIXP_FOUND_TNC 0xe9
#define SIXP_CON_ON 0x68
#define SIXP_DCD_MASK 0x08
#define SIXP_DAMA_OFF 0
/* default level 2 parameters */
#define SIXP_TXDELAY (HZ/4) /* in 1 s */
#define SIXP_PERSIST 50 /* in 256ths */
#define SIXP_SLOTTIME (HZ/10) /* in 1 s */
#define SIXP_INIT_RESYNC_TIMEOUT (3*HZ/2) /* in 1 s */
#define SIXP_RESYNC_TIMEOUT 5*HZ /* in 1 s */
/* 6pack configuration. */
#define SIXP_NRUNIT 31 /* MAX number of 6pack channels */
#define SIXP_MTU 256 /* Default MTU */
enum sixpack_flags {
SIXPF_ERROR, /* Parity, etc. error */
};
struct sixpack {
/* Various fields. */
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. */
unsigned char *rbuff; /* receiver buffer */
int rcount; /* received chars counter */
unsigned char *xbuff; /* transmitter buffer */
unsigned char *xhead; /* next byte to XMIT */
int xleft; /* bytes left in XMIT queue */
unsigned char raw_buf[4];
unsigned char cooked_buf[400];
unsigned int rx_count;
unsigned int rx_count_cooked;
int mtu; /* Our mtu (to spot changes!) */
int buffsize; /* Max buffers sizes */
unsigned long flags; /* Flag values/ mode etc */
unsigned char mode; /* 6pack mode */
/* 6pack stuff */
unsigned char tx_delay;
unsigned char persistence;
unsigned char slottime;
unsigned char duplex;
unsigned char led_state;
unsigned char status;
unsigned char status1;
unsigned char status2;
unsigned char tx_enable;
unsigned char tnc_state;
struct timer_list tx_t;
struct timer_list resync_t;
atomic_t refcnt;
struct semaphore dead_sem;
spinlock_t lock;
};
#define AX25_6PACK_HEADER_LEN 0
static void sixpack_decode(struct sixpack *, unsigned char[], int);
static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
/*
* Perform the persistence/slottime algorithm for CSMA access. If the
* persistence check was successful, write the data to the serial driver.
* Note that in case of DAMA operation, the data is not sent here.
*/
static void sp_xmit_on_air(unsigned long channel)
{
struct sixpack *sp = (struct sixpack *) channel;
int actual, when = sp->slottime;
static unsigned char random;
random = random * 17 + 41;
if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {
sp->led_state = 0x70;
sp->tty->ops->write(sp->tty, &sp->led_state, 1);
sp->tx_enable = 1;
actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
sp->xleft -= actual;
sp->xhead += actual;
sp->led_state = 0x60;
sp->tty->ops->write(sp->tty, &sp->led_state, 1);
sp->status2 = 0;
} else
mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
}
/* ----> 6pack timer interrupt handler and friends. <---- */
/* Encapsulate one AX.25 frame and stuff into a TTY queue. */
static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
{
unsigned char *msg, *p = icp;
int actual, count;
if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
msg = "oversized transmit packet!";
goto out_drop;
}
if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
msg = "oversized transmit packet!";
goto out_drop;
}
if (p[0] > 5) {
msg = "invalid KISS command";
goto out_drop;
}
if ((p[0] != 0) && (len > 2)) {
msg = "KISS control packet too long";
goto out_drop;
}
if ((p[0] == 0) && (len < 15)) {
msg = "bad AX.25 packet to transmit";
goto out_drop;
}
count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
switch (p[0]) {
case 1: sp->tx_delay = p[1];
return;
case 2: sp->persistence = p[1];
return;
case 3: sp->slottime = p[1];
return;
case 4: /* ignored */
return;
case 5: sp->duplex = p[1];
return;
}
if (p[0] != 0)
return;
/*
* In case of fullduplex or DAMA operation, we don't take care about the
* state of the DCD or of any timers, as the determination of the
* correct time to send is the job of the AX.25 layer. We send
* immediately after data has arrived.
*/
if (sp->duplex == 1) {
sp->led_state = 0x70;
sp->tty->ops->write(sp->tty, &sp->led_state, 1);
sp->tx_enable = 1;
actual = sp->tty->ops->write(sp->tty, sp->xbuff, count);
sp->xleft = count - actual;
sp->xhead = sp->xbuff + actual;
sp->led_state = 0x60;
sp->tty->ops->write(sp->tty, &sp->led_state, 1);
} else {
sp->xleft = count;
sp->xhead = sp->xbuff;
sp->status2 = count;
sp_xmit_on_air((unsigned long)sp);
}
return;
out_drop:
sp->dev->stats.tx_dropped++;
netif_start_queue(sp->dev);
if (net_ratelimit())
printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
}
/* Encapsulate an IP datagram and kick it into a TTY queue. */
static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct sixpack *sp = netdev_priv(dev);
spin_lock_bh(&sp->lock);
/* We were not busy, so we are now... :-) */
netif_stop_queue(dev);
dev->stats.tx_bytes += skb->len;
sp_encaps(sp, skb->data, skb->len);
spin_unlock_bh(&sp->lock);
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
static int sp_open_dev(struct net_device *dev)
{
struct sixpack *sp = netdev_priv(dev);
if (sp->tty == NULL)
return -ENODEV;
return 0;
}
/* Close the low-level part of the 6pack channel. */
static int sp_close(struct net_device *dev)
{
struct sixpack *sp = netdev_priv(dev);
spin_lock_bh(&sp->lock);
if (sp->tty) {
/* TTY discipline is running. */
clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
}
netif_stop_queue(dev);
spin_unlock_bh(&sp->lock);
return 0;
}
/* Return the frame type ID */
static int sp_header(struct sk_buff *skb, struct net_device *dev,
unsigned short type, const void *daddr,
const void *saddr, unsigned len)
{
#ifdef CONFIG_INET
if (type != ETH_P_AX25)
return ax25_hard_header(skb, dev, type, daddr, saddr, len);
#endif
return 0;
}
static int sp_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 int sp_rebuild_header(struct sk_buff *skb)
{
#ifdef CONFIG_INET
return ax25_rebuild_header(skb);
#else
return 0;
#endif
}
static const struct header_ops sp_header_ops = {
.create = sp_header,
.rebuild = sp_rebuild_header,
};
static const struct net_device_ops sp_netdev_ops = {
.ndo_open = sp_open_dev,
.ndo_stop = sp_close,
.ndo_start_xmit = sp_xmit,
.ndo_set_mac_address = sp_set_mac_address,
};
static void sp_setup(struct net_device *dev)
{
/* Finish setting up the DEVICE info. */
dev->netdev_ops = &sp_netdev_ops;
dev->destructor = free_netdev;
dev->mtu = SIXP_MTU;
dev->hard_header_len = AX25_MAX_HEADER_LEN;
dev->header_ops = &sp_header_ops;
dev->addr_len = AX25_ADDR_LEN;
dev->type = ARPHRD_AX25;
dev->tx_queue_len = 10;
/* Only activated in AX.25 mode */
memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN);
dev->flags = 0;
}
/* Send one completely decapsulated IP datagram to the IP layer. */
/*
* This is the routine that sends the received data to the kernel AX.25.
* 'cmd' is the KISS command. For AX.25 data, it is zero.
*/
static void sp_bump(struct sixpack *sp, char cmd)
{
struct sk_buff *skb;
int count;
unsigned char *ptr;
count = sp->rcount + 1;
sp->dev->stats.rx_bytes += count;
if ((skb = dev_alloc_skb(count)) == NULL)
goto out_mem;
ptr = skb_put(skb, count);
*ptr++ = cmd; /* KISS command */
memcpy(ptr, sp->cooked_buf + 1, count);
skb->protocol = ax25_type_trans(skb, sp->dev);
netif_rx(skb);
sp->dev->stats.rx_packets++;
return;
out_mem:
sp->dev->stats.rx_dropped++;
}
/* ----------------------------------------------------------------------- */
/*
* 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 sixpack *sp_get(struct tty_struct *tty)
{
struct sixpack *sp;
read_lock(&disc_data_lock);
sp = tty->disc_data;
if (sp)
atomic_inc(&sp->refcnt);
read_unlock(&disc_data_lock);
return sp;
}
static void sp_put(struct sixpack *sp)
{
if (atomic_dec_and_test(&sp->refcnt))
up(&sp->dead_sem);
}
/*
* Called by the TTY driver when there's room for more data. If we have
* more packets to send, we send them here.
*/
static void sixpack_write_wakeup(struct tty_struct *tty)
{
struct sixpack *sp = sp_get(tty);
int actual;
if (!sp)
return;
if (sp->xleft <= 0) {
/* Now serial buffer is almost free & we can start
* transmission of another packet */
sp->dev->stats.tx_packets++;
clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
sp->tx_enable = 0;
netif_wake_queue(sp->dev);
goto out;
}
if (sp->tx_enable) {
actual = tty->ops->write(tty, sp->xhead, sp->xleft);
sp->xleft -= actual;
sp->xhead += actual;
}
out:
sp_put(sp);
}
/* ----------------------------------------------------------------------- */
/*
* Handle the 'receiver data ready' interrupt.
* This function is called by the 'tty_io' module in the kernel when
* a block of 6pack data has been received, which can now be decapsulated
* and sent on to some IP 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 sixpack_receive_buf(struct tty_struct *tty,
const unsigned char *cp, char *fp, int count)
{
struct sixpack *sp;
unsigned char buf[512];
int count1;
if (!count)
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;
sp = sp_get(tty);
if (!sp)
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;
memcpy(buf, cp, count < sizeof(buf) ? count : sizeof(buf));
/* Read the characters out of the buffer */
count1 = count;
while (count) {
count--;
if (fp && *fp++) {
if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
sp->dev->stats.rx_errors++;
continue;
}
}
sixpack_decode(sp, buf, count1);
sp_put(sp);
tty_unthrottle(tty);
}
/*
* Try to resync the TNC. Called by the resync timer defined in
* decode_prio_command
*/
#define TNC_UNINITIALIZED 0
#define TNC_UNSYNC_STARTUP 1
#define TNC_UNSYNCED 2
#define TNC_IN_SYNC 3
static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
{
char *msg;
switch (new_tnc_state) {
default: /* gcc oh piece-o-crap ... */
case TNC_UNSYNC_STARTUP:
msg = "Synchronizing with TNC";
break;
case TNC_UNSYNCED:
msg = "Lost synchronization with TNC\n";
break;
case TNC_IN_SYNC:
msg = "Found TNC";
break;
}
sp->tnc_state = new_tnc_state;
printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
}
static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
{
int old_tnc_state = sp->tnc_state;
if (old_tnc_state != new_tnc_state)
__tnc_set_sync_state(sp, new_tnc_state);
}
static void resync_tnc(unsigned long channel)
{
struct sixpack *sp = (struct sixpack *) channel;
static char resync_cmd = 0xe8;
/* clear any data that might have been received */
sp->rx_count = 0;
sp->rx_count_cooked = 0;
/* reset state machine */
sp->status = 1;
sp->status1 = 1;
sp->status2 = 0;
/* resync the TNC */
sp->led_state = 0x60;
sp->tty->ops->write(sp->tty, &sp->led_state, 1);
sp->tty->ops->write(sp->tty, &resync_cmd, 1);
/* Start resync timer again -- the TNC might be still absent */
del_timer(&sp->resync_t);
sp->resync_t.data = (unsigned long) sp;
sp->resync_t.function = resync_tnc;
sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
add_timer(&sp->resync_t);
}
static inline int tnc_init(struct sixpack *sp)
{
unsigned char inbyte = 0xe8;
tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
sp->tty->ops->write(sp->tty, &inbyte, 1);
del_timer(&sp->resync_t);
sp->resync_t.data = (unsigned long) sp;
sp->resync_t.function = resync_tnc;
sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
add_timer(&sp->resync_t);
return 0;
}
/*
* Open the high-level part of the 6pack channel.
* This function is called by the TTY module when the
* 6pack line discipline is called for. Because we are
* sure the tty line exists, we only have to link it to
* a free 6pcack channel...
*/
static int sixpack_open(struct tty_struct *tty)
{
char *rbuff = NULL, *xbuff = NULL;
struct net_device *dev;
struct sixpack *sp;
unsigned long len;
int err = 0;
if (!capable(CAP_NET_ADMIN))
return -EPERM;
if (tty->ops->write == NULL)
return -EOPNOTSUPP;
dev = alloc_netdev(sizeof(struct sixpack), "sp%d", sp_setup);
if (!dev) {
err = -ENOMEM;
goto out;
}
sp = netdev_priv(dev);
sp->dev = dev;
spin_lock_init(&sp->lock);
atomic_set(&sp->refcnt, 1);
sema_init(&sp->dead_sem, 0);
/* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
len = dev->mtu * 2;
rbuff = kmalloc(len + 4, GFP_KERNEL);
xbuff = kmalloc(len + 4, GFP_KERNEL);
if (rbuff == NULL || xbuff == NULL) {
err = -ENOBUFS;
goto out_free;
}
spin_lock_bh(&sp->lock);
sp->tty = tty;
sp->rbuff = rbuff;
sp->xbuff = xbuff;
sp->mtu = AX25_MTU + 73;
sp->buffsize = len;
sp->rcount = 0;
sp->rx_count = 0;
sp->rx_count_cooked = 0;
sp->xleft = 0;
sp->flags = 0; /* Clear ESCAPE & ERROR flags */
sp->duplex = 0;
sp->tx_delay = SIXP_TXDELAY;
sp->persistence = SIXP_PERSIST;
sp->slottime = SIXP_SLOTTIME;
sp->led_state = 0x60;
sp->status = 1;
sp->status1 = 1;
sp->status2 = 0;
sp->tx_enable = 0;
netif_start_queue(dev);
init_timer(&sp->tx_t);
sp->tx_t.function = sp_xmit_on_air;
sp->tx_t.data = (unsigned long) sp;
init_timer(&sp->resync_t);
spin_unlock_bh(&sp->lock);
/* Done. We have linked the TTY line to a channel. */
tty->disc_data = sp;
[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 = 65536;
/* Now we're ready to register. */
err = register_netdev(dev);
if (err)
goto out_free;
tnc_init(sp);
return 0;
out_free:
kfree(xbuff);
kfree(rbuff);
if (dev)
free_netdev(dev);
out:
return err;
}
/*
* Close down a 6pack channel.
* This means flushing out any pending queues, and then restoring the
* TTY line discipline to what it was before it got hooked to 6pack
* (which usually is TTY again).
*/
static void sixpack_close(struct tty_struct *tty)
{
struct sixpack *sp;
write_lock_bh(&disc_data_lock);
sp = tty->disc_data;
tty->disc_data = NULL;
write_unlock_bh(&disc_data_lock);
if (!sp)
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(&sp->refcnt))
down(&sp->dead_sem);
unregister_netdev(sp->dev);
del_timer(&sp->tx_t);
del_timer(&sp->resync_t);
/* Free all 6pack frame buffers. */
kfree(sp->rbuff);
kfree(sp->xbuff);
}
/* Perform I/O control on an active 6pack channel. */
static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg)
{
struct sixpack *sp = sp_get(tty);
struct net_device *dev;
unsigned int tmp, err;
if (!sp)
return -ENXIO;
dev = sp->dev;
switch(cmd) {
case SIOCGIFNAME:
err = copy_to_user((void __user *) arg, dev->name,
strlen(dev->name) + 1) ? -EFAULT : 0;
break;
case SIOCGIFENCAP:
err = put_user(0, (int __user *) arg);
break;
case SIOCSIFENCAP:
if (get_user(tmp, (int __user *) arg)) {
err = -EFAULT;
break;
}
sp->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 = tty_mode_ioctl(tty, file, cmd, arg);
}
sp_put(sp);
return err;
}
#ifdef CONFIG_COMPAT
static long sixpack_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 sixpack_ioctl(tty, file, cmd,
(unsigned long)compat_ptr(arg));
}
return -ENOIOCTLCMD;
}
#endif
static struct tty_ldisc_ops sp_ldisc = {
.owner = THIS_MODULE,
.magic = TTY_LDISC_MAGIC,
.name = "6pack",
.open = sixpack_open,
.close = sixpack_close,
.ioctl = sixpack_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = sixpack_compat_ioctl,
#endif
.receive_buf = sixpack_receive_buf,
.write_wakeup = sixpack_write_wakeup,
};
/* Initialize 6pack control device -- register 6pack line discipline */
static const char msg_banner[] __initconst = KERN_INFO \
"AX.25: 6pack driver, " SIXPACK_VERSION "\n";
static const char msg_regfail[] __initconst = KERN_ERR \
"6pack: can't register line discipline (err = %d)\n";
static int __init sixpack_init_driver(void)
{
int status;
printk(msg_banner);
/* Register the provided line protocol discipline */
if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
printk(msg_regfail, status);
return status;
}
static const char msg_unregfail[] = KERN_ERR \
"6pack: can't unregister line discipline (err = %d)\n";
static void __exit sixpack_exit_driver(void)
{
int ret;
if ((ret = tty_unregister_ldisc(N_6PACK)))
printk(msg_unregfail, ret);
}
/* encode an AX.25 packet into 6pack */
static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
int length, unsigned char tx_delay)
{
int count = 0;
unsigned char checksum = 0, buf[400];
int raw_count = 0;
tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
tx_buf_raw[raw_count++] = SIXP_SEOF;
buf[0] = tx_delay;
for (count = 1; count < length; count++)
buf[count] = tx_buf[count];
for (count = 0; count < length; count++)
checksum += buf[count];
buf[length] = (unsigned char) 0xff - checksum;
for (count = 0; count <= length; count++) {
if ((count % 3) == 0) {
tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
} else if ((count % 3) == 1) {
tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
} else {
tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
tx_buf_raw[raw_count++] = (buf[count] >> 2);
}
}
if ((length % 3) != 2)
raw_count++;
tx_buf_raw[raw_count++] = SIXP_SEOF;
return raw_count;
}
/* decode 4 sixpack-encoded bytes into 3 data bytes */
static void decode_data(struct sixpack *sp, unsigned char inbyte)
{
unsigned char *buf;
if (sp->rx_count != 3) {
sp->raw_buf[sp->rx_count++] = inbyte;
return;
}
buf = sp->raw_buf;
sp->cooked_buf[sp->rx_count_cooked++] =
buf[0] | ((buf[1] << 2) & 0xc0);
sp->cooked_buf[sp->rx_count_cooked++] =
(buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
sp->cooked_buf[sp->rx_count_cooked++] =
(buf[2] & 0x03) | (inbyte << 2);
sp->rx_count = 0;
}
/* identify and execute a 6pack priority command byte */
static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
{
unsigned char channel;
int actual;
channel = cmd & SIXP_CHN_MASK;
if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
/* RX and DCD flags can only be set in the same prio command,
if the DCD flag has been set without the RX flag in the previous
prio command. If DCD has not been set before, something in the
transmission has gone wrong. In this case, RX and DCD are
cleared in order to prevent the decode_data routine from
reading further data that might be corrupt. */
if (((sp->status & SIXP_DCD_MASK) == 0) &&
((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
if (sp->status != 1)
printk(KERN_DEBUG "6pack: protocol violation\n");
else
sp->status = 0;
cmd &= ~SIXP_RX_DCD_MASK;
}
sp->status = cmd & SIXP_PRIO_DATA_MASK;
} else { /* output watchdog char if idle */
if ((sp->status2 != 0) && (sp->duplex == 1)) {
sp->led_state = 0x70;
sp->tty->ops->write(sp->tty, &sp->led_state, 1);
sp->tx_enable = 1;
actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
sp->xleft -= actual;
sp->xhead += actual;
sp->led_state = 0x60;
sp->status2 = 0;
}
}
/* needed to trigger the TNC watchdog */
sp->tty->ops->write(sp->tty, &sp->led_state, 1);
/* if the state byte has been received, the TNC is present,
so the resync timer can be reset. */
if (sp->tnc_state == TNC_IN_SYNC) {
del_timer(&sp->resync_t);
sp->resync_t.data = (unsigned long) sp;
sp->resync_t.function = resync_tnc;
sp->resync_t.expires = jiffies + SIXP_INIT_RESYNC_TIMEOUT;
add_timer(&sp->resync_t);
}
sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
}
/* identify and execute a standard 6pack command byte */
static void decode_std_command(struct sixpack *sp, unsigned char cmd)
{
unsigned char checksum = 0, rest = 0, channel;
short i;
channel = cmd & SIXP_CHN_MASK;
switch (cmd & SIXP_CMD_MASK) { /* normal command */
case SIXP_SEOF:
if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
if ((sp->status & SIXP_RX_DCD_MASK) ==
SIXP_RX_DCD_MASK) {
sp->led_state = 0x68;
sp->tty->ops->write(sp->tty, &sp->led_state, 1);
}
} else {
sp->led_state = 0x60;
/* fill trailing bytes with zeroes */
sp->tty->ops->write(sp->tty, &sp->led_state, 1);
rest = sp->rx_count;
if (rest != 0)
for (i = rest; i <= 3; i++)
decode_data(sp, 0);
if (rest == 2)
sp->rx_count_cooked -= 2;
else if (rest == 3)
sp->rx_count_cooked -= 1;
for (i = 0; i < sp->rx_count_cooked; i++)
checksum += sp->cooked_buf[i];
if (checksum != SIXP_CHKSUM) {
printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
} else {
sp->rcount = sp->rx_count_cooked-2;
sp_bump(sp, 0);
}
sp->rx_count_cooked = 0;
}
break;
case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
break;
case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
break;
case SIXP_RX_BUF_OVL:
printk(KERN_DEBUG "6pack: RX buffer overflow\n");
}
}
/* decode a 6pack packet */
static void
sixpack_decode(struct sixpack *sp, unsigned char *pre_rbuff, int count)
{
unsigned char inbyte;
int count1;
for (count1 = 0; count1 < count; count1++) {
inbyte = pre_rbuff[count1];
if (inbyte == SIXP_FOUND_TNC) {
tnc_set_sync_state(sp, TNC_IN_SYNC);
del_timer(&sp->resync_t);
}
if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
decode_prio_command(sp, inbyte);
else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
decode_std_command(sp, inbyte);
else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
decode_data(sp, inbyte);
}
}
MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
MODULE_DESCRIPTION("6pack driver for AX.25");
MODULE_LICENSE("GPL");
MODULE_ALIAS_LDISC(N_6PACK);
module_init(sixpack_init_driver);
module_exit(sixpack_exit_driver);