linux_dsm_epyc7002/drivers/net/slip/slip.c

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/*
* slip.c This module implements the SLIP protocol for kernel-based
* devices like TTY. It interfaces between a raw TTY, and the
* kernel's INET protocol layers.
*
* Version: @(#)slip.c 0.8.3 12/24/94
*
* Authors: Laurence Culhane, <loz@holmes.demon.co.uk>
* Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
*
* Fixes:
* Alan Cox : Sanity checks and avoid tx overruns.
* Has a new sl->mtu field.
* Alan Cox : Found cause of overrun. ifconfig sl0
* mtu upwards. Driver now spots this
* and grows/shrinks its buffers(hack!).
* Memory leak if you run out of memory
* setting up a slip driver fixed.
* Matt Dillon : Printable slip (borrowed from NET2E)
* Pauline Middelink : Slip driver fixes.
* Alan Cox : Honours the old SL_COMPRESSED flag
* Alan Cox : KISS AX.25 and AXUI IP support
* Michael Riepe : Automatic CSLIP recognition added
* Charles Hedrick : CSLIP header length problem fix.
* Alan Cox : Corrected non-IP cases of the above.
* Alan Cox : Now uses hardware type as per FvK.
* Alan Cox : Default to 192.168.0.0 (RFC 1597)
* A.N.Kuznetsov : dev_tint() recursion fix.
* Dmitry Gorodchanin : SLIP memory leaks
* Dmitry Gorodchanin : Code cleanup. Reduce tty driver
* buffering from 4096 to 256 bytes.
* Improving SLIP response time.
* CONFIG_SLIP_MODE_SLIP6.
* ifconfig sl? up & down now works
* correctly.
* Modularization.
* Alan Cox : Oops - fix AX.25 buffer lengths
* Dmitry Gorodchanin : Even more cleanups. Preserve CSLIP
* statistics. Include CSLIP code only
* if it really needed.
* Alan Cox : Free slhc buffers in the right place.
* Alan Cox : Allow for digipeated IP over AX.25
* Matti Aarnio : Dynamic SLIP devices, with ideas taken
* from Jim Freeman's <jfree@caldera.com>
* dynamic PPP devices. We do NOT kfree()
* device entries, just reg./unreg. them
* as they are needed. We kfree() them
* at module cleanup.
* With MODULE-loading ``insmod'', user
* can issue parameter: slip_maxdev=1024
* (Or how much he/she wants.. Default
* is 256)
* Stanislav Voronyi : Slip line checking, with ideas taken
* from multislip BSDI driver which was
* written by Igor Chechik, RELCOM Corp.
* Only algorithms have been ported to
* Linux SLIP driver.
* Vitaly E. Lavrov : Sane behaviour on tty hangup.
* Alexey Kuznetsov : Cleanup interfaces to tty & netdevice
* modules.
*/
#define SL_CHECK_TRANSMIT
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <asm/uaccess.h>
#include <linux/bitops.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/in.h>
#include <linux/tty.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/if_arp.h>
#include <linux/if_slip.h>
#include <linux/compat.h>
#include <linux/delay.h>
#include <linux/init.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 15:04:11 +07:00
#include <linux/slab.h>
slip: Fix deadlock in write_wakeup Use schedule_work() to avoid potentially taking the spinlock in interrupt context. Commit cc9fa74e2a ("slip/slcan: added locking in wakeup function") added necessary locking to the wakeup function and 367525c8c2/ddcde142be ("can: slcan: Fix spinlock variant") converted it to spin_lock_bh() because the lock is also taken in timers. Disabling softirqs is not sufficient, however, as tty drivers may call write_wakeup from interrupt context. This driver calls tty->ops->write() with its spinlock held, which may immediately cause an interrupt on the same CPU and subsequent spin_bug(). Simply converting to spin_lock_irq/irqsave() prevents this deadlock, but causes lockdep to point out a possible circular locking dependency between these locks: (&(&sl->lock)->rlock){-.....}, at: slip_write_wakeup (&port_lock_key){-.....}, at: serial8250_handle_irq.part.13 The slip transmit is holding the slip spinlock when calling the tty write. This grabs the port lock. On an interrupt, the handler grabs the port lock and calls write_wakeup which grabs the slip lock. This could be a problem if a serial interrupt occurs on another CPU during the slip transmit. To deal with these issues, don't grab the lock in the wakeup function by deferring the writeout to a workqueue. Also hold the lock during close when de-assigning the tty pointer to safely disarm the worker and timers. This bug is easily reproducible on the first transmit when slip is used with the standard 8250 serial driver. [<c0410b7c>] (spin_bug+0x0/0x38) from [<c006109c>] (do_raw_spin_lock+0x60/0x1d0) r5:eab27000 r4:ec02754c [<c006103c>] (do_raw_spin_lock+0x0/0x1d0) from [<c04185c0>] (_raw_spin_lock+0x28/0x2c) r10:0000001f r9:eabb814c r8:eabb8140 r7:40070193 r6:ec02754c r5:eab27000 r4:ec02754c r3:00000000 [<c0418598>] (_raw_spin_lock+0x0/0x2c) from [<bf3a0220>] (slip_write_wakeup+0x50/0xe0 [slip]) r4:ec027540 r3:00000003 [<bf3a01d0>] (slip_write_wakeup+0x0/0xe0 [slip]) from [<c026e420>] (tty_wakeup+0x48/0x68) r6:00000000 r5:ea80c480 r4:eab27000 r3:bf3a01d0 [<c026e3d8>] (tty_wakeup+0x0/0x68) from [<c028a8ec>] (uart_write_wakeup+0x2c/0x30) r5:ed68ea90 r4:c06790d8 [<c028a8c0>] (uart_write_wakeup+0x0/0x30) from [<c028dc44>] (serial8250_tx_chars+0x114/0x170) [<c028db30>] (serial8250_tx_chars+0x0/0x170) from [<c028dffc>] (serial8250_handle_irq+0xa0/0xbc) r6:000000c2 r5:00000060 r4:c06790d8 r3:00000000 [<c028df5c>] (serial8250_handle_irq+0x0/0xbc) from [<c02933a4>] (dw8250_handle_irq+0x38/0x64) r7:00000000 r6:edd2f390 r5:000000c2 r4:c06790d8 [<c029336c>] (dw8250_handle_irq+0x0/0x64) from [<c028d2f4>] (serial8250_interrupt+0x44/0xc4) r6:00000000 r5:00000000 r4:c06791c4 r3:c029336c [<c028d2b0>] (serial8250_interrupt+0x0/0xc4) from [<c0067fe4>] (handle_irq_event_percpu+0xb4/0x2b0) r10:c06790d8 r9:eab27000 r8:00000000 r7:00000000 r6:0000001f r5:edd52980 r4:ec53b6c0 r3:c028d2b0 [<c0067f30>] (handle_irq_event_percpu+0x0/0x2b0) from [<c006822c>] (handle_irq_event+0x4c/0x6c) r10:c06790d8 r9:eab27000 r8:c0673ae0 r7:c05c2020 r6:ec53b6c0 r5:edd529d4 r4:edd52980 [<c00681e0>] (handle_irq_event+0x0/0x6c) from [<c006b140>] (handle_level_irq+0xe8/0x100) r6:00000000 r5:edd529d4 r4:edd52980 r3:00022000 [<c006b058>] (handle_level_irq+0x0/0x100) from [<c00676f8>] (generic_handle_irq+0x30/0x40) r5:0000001f r4:0000001f [<c00676c8>] (generic_handle_irq+0x0/0x40) from [<c000f57c>] (handle_IRQ+0xd0/0x13c) r4:ea997b18 r3:000000e0 [<c000f4ac>] (handle_IRQ+0x0/0x13c) from [<c00086c4>] (armada_370_xp_handle_irq+0x4c/0x118) r8:000003ff r7:ea997b18 r6:ffffffff r5:60070013 r4:c0674dc0 [<c0008678>] (armada_370_xp_handle_irq+0x0/0x118) from [<c0013840>] (__irq_svc+0x40/0x70) Exception stack(0xea997b18 to 0xea997b60) 7b00: 00000001 20070013 7b20: 00000000 0000000b 20070013 eab27000 20070013 00000000 ed10103e eab27000 7b40: c06790d8 ea997b74 ea997b60 ea997b60 c04186c0 c04186c8 60070013 ffffffff r9:eab27000 r8:ed10103e r7:ea997b4c r6:ffffffff r5:60070013 r4:c04186c8 [<c04186a4>] (_raw_spin_unlock_irqrestore+0x0/0x54) from [<c0288fc0>] (uart_start+0x40/0x44) r4:c06790d8 r3:c028ddd8 [<c0288f80>] (uart_start+0x0/0x44) from [<c028982c>] (uart_write+0xe4/0xf4) r6:0000003e r5:00000000 r4:ed68ea90 r3:0000003e [<c0289748>] (uart_write+0x0/0xf4) from [<bf3a0d20>] (sl_xmit+0x1c4/0x228 [slip]) r10:ed388e60 r9:0000003c r8:ffffffdd r7:0000003e r6:ec02754c r5:ea717eb8 r4:ec027000 [<bf3a0b5c>] (sl_xmit+0x0/0x228 [slip]) from [<c0368d74>] (dev_hard_start_xmit+0x39c/0x6d0) r8:eaf163c0 r7:ec027000 r6:ea717eb8 r5:00000000 r4:00000000 Signed-off-by: Tyler Hall <tylerwhall@gmail.com> Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: Andre Naujoks <nautsch2@gmail.com> Cc: David S. Miller <davem@davemloft.net> Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-16 09:23:16 +07:00
#include <linux/workqueue.h>
#include "slip.h"
#ifdef CONFIG_INET
#include <linux/ip.h>
#include <linux/tcp.h>
#include <net/slhc_vj.h>
#endif
#define SLIP_VERSION "0.8.4-NET3.019-NEWTTY"
static struct net_device **slip_devs;
static int slip_maxdev = SL_NRUNIT;
module_param(slip_maxdev, int, 0);
MODULE_PARM_DESC(slip_maxdev, "Maximum number of slip devices");
static int slip_esc(unsigned char *p, unsigned char *d, int len);
static void slip_unesc(struct slip *sl, unsigned char c);
#ifdef CONFIG_SLIP_MODE_SLIP6
static int slip_esc6(unsigned char *p, unsigned char *d, int len);
static void slip_unesc6(struct slip *sl, unsigned char c);
#endif
#ifdef CONFIG_SLIP_SMART
static void sl_keepalive(unsigned long sls);
static void sl_outfill(unsigned long sls);
static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
#endif
/********************************
* Buffer administration routines:
* sl_alloc_bufs()
* sl_free_bufs()
* sl_realloc_bufs()
*
* NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because
* sl_realloc_bufs provides strong atomicity and reallocation
* on actively running device.
*********************************/
/*
Allocate channel buffers.
*/
static int sl_alloc_bufs(struct slip *sl, int mtu)
{
int err = -ENOBUFS;
unsigned long len;
char *rbuff = NULL;
char *xbuff = NULL;
#ifdef SL_INCLUDE_CSLIP
char *cbuff = NULL;
struct slcompress *slcomp = NULL;
#endif
/*
* Allocate the SLIP frame buffers:
*
* rbuff Receive buffer.
* xbuff Transmit buffer.
* cbuff Temporary compression buffer.
*/
len = mtu * 2;
/*
* allow for arrival of larger UDP packets, even if we say not to
* also fixes a bug in which SunOS sends 512-byte packets even with
* an MSS of 128
*/
if (len < 576 * 2)
len = 576 * 2;
rbuff = kmalloc(len + 4, GFP_KERNEL);
if (rbuff == NULL)
goto err_exit;
xbuff = kmalloc(len + 4, GFP_KERNEL);
if (xbuff == NULL)
goto err_exit;
#ifdef SL_INCLUDE_CSLIP
cbuff = kmalloc(len + 4, GFP_KERNEL);
if (cbuff == NULL)
goto err_exit;
slcomp = slhc_init(16, 16);
if (slcomp == NULL)
goto err_exit;
#endif
spin_lock_bh(&sl->lock);
if (sl->tty == NULL) {
spin_unlock_bh(&sl->lock);
err = -ENODEV;
goto err_exit;
}
sl->mtu = mtu;
sl->buffsize = len;
sl->rcount = 0;
sl->xleft = 0;
rbuff = xchg(&sl->rbuff, rbuff);
xbuff = xchg(&sl->xbuff, xbuff);
#ifdef SL_INCLUDE_CSLIP
cbuff = xchg(&sl->cbuff, cbuff);
slcomp = xchg(&sl->slcomp, slcomp);
#endif
#ifdef CONFIG_SLIP_MODE_SLIP6
sl->xdata = 0;
sl->xbits = 0;
#endif
spin_unlock_bh(&sl->lock);
err = 0;
/* Cleanup */
err_exit:
#ifdef SL_INCLUDE_CSLIP
kfree(cbuff);
slhc_free(slcomp);
#endif
kfree(xbuff);
kfree(rbuff);
return err;
}
/* Free a SLIP channel buffers. */
static void sl_free_bufs(struct slip *sl)
{
/* Free all SLIP frame buffers. */
kfree(xchg(&sl->rbuff, NULL));
kfree(xchg(&sl->xbuff, NULL));
#ifdef SL_INCLUDE_CSLIP
kfree(xchg(&sl->cbuff, NULL));
slhc_free(xchg(&sl->slcomp, NULL));
#endif
}
/*
Reallocate slip channel buffers.
*/
static int sl_realloc_bufs(struct slip *sl, int mtu)
{
int err = 0;
struct net_device *dev = sl->dev;
unsigned char *xbuff, *rbuff;
#ifdef SL_INCLUDE_CSLIP
unsigned char *cbuff;
#endif
int len = mtu * 2;
/*
* allow for arrival of larger UDP packets, even if we say not to
* also fixes a bug in which SunOS sends 512-byte packets even with
* an MSS of 128
*/
if (len < 576 * 2)
len = 576 * 2;
[PATCH] getting rid of all casts of k[cmz]alloc() calls Run this: #!/bin/sh for f in $(grep -Erl "\([^\)]*\) *k[cmz]alloc" *) ; do echo "De-casting $f..." perl -pi -e "s/ ?= ?\([^\)]*\) *(k[cmz]alloc) *\(/ = \1\(/" $f done And then go through and reinstate those cases where code is casting pointers to non-pointers. And then drop a few hunks which conflicted with outstanding work. Cc: Russell King <rmk@arm.linux.org.uk>, Ian Molton <spyro@f2s.com> Cc: Mikael Starvik <starvik@axis.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Greg KH <greg@kroah.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Paul Fulghum <paulkf@microgate.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Karsten Keil <kkeil@suse.de> Cc: Mauro Carvalho Chehab <mchehab@infradead.org> Cc: Jeff Garzik <jeff@garzik.org> Cc: James Bottomley <James.Bottomley@steeleye.com> Cc: Ian Kent <raven@themaw.net> Cc: Steven French <sfrench@us.ibm.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Neil Brown <neilb@cse.unsw.edu.au> Cc: Jaroslav Kysela <perex@suse.cz> Cc: Takashi Iwai <tiwai@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-13 15:35:56 +07:00
xbuff = kmalloc(len + 4, GFP_ATOMIC);
rbuff = kmalloc(len + 4, GFP_ATOMIC);
#ifdef SL_INCLUDE_CSLIP
[PATCH] getting rid of all casts of k[cmz]alloc() calls Run this: #!/bin/sh for f in $(grep -Erl "\([^\)]*\) *k[cmz]alloc" *) ; do echo "De-casting $f..." perl -pi -e "s/ ?= ?\([^\)]*\) *(k[cmz]alloc) *\(/ = \1\(/" $f done And then go through and reinstate those cases where code is casting pointers to non-pointers. And then drop a few hunks which conflicted with outstanding work. Cc: Russell King <rmk@arm.linux.org.uk>, Ian Molton <spyro@f2s.com> Cc: Mikael Starvik <starvik@axis.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Greg KH <greg@kroah.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Paul Fulghum <paulkf@microgate.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Karsten Keil <kkeil@suse.de> Cc: Mauro Carvalho Chehab <mchehab@infradead.org> Cc: Jeff Garzik <jeff@garzik.org> Cc: James Bottomley <James.Bottomley@steeleye.com> Cc: Ian Kent <raven@themaw.net> Cc: Steven French <sfrench@us.ibm.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Neil Brown <neilb@cse.unsw.edu.au> Cc: Jaroslav Kysela <perex@suse.cz> Cc: Takashi Iwai <tiwai@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-13 15:35:56 +07:00
cbuff = kmalloc(len + 4, GFP_ATOMIC);
#endif
#ifdef SL_INCLUDE_CSLIP
if (xbuff == NULL || rbuff == NULL || cbuff == NULL) {
#else
if (xbuff == NULL || rbuff == NULL) {
#endif
if (mtu > sl->mtu) {
printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n",
dev->name);
err = -ENOBUFS;
}
goto done;
}
spin_lock_bh(&sl->lock);
err = -ENODEV;
if (sl->tty == NULL)
goto done_on_bh;
xbuff = xchg(&sl->xbuff, xbuff);
rbuff = xchg(&sl->rbuff, rbuff);
#ifdef SL_INCLUDE_CSLIP
cbuff = xchg(&sl->cbuff, cbuff);
#endif
if (sl->xleft) {
if (sl->xleft <= len) {
memcpy(sl->xbuff, sl->xhead, sl->xleft);
} else {
sl->xleft = 0;
dev->stats.tx_dropped++;
}
}
sl->xhead = sl->xbuff;
if (sl->rcount) {
if (sl->rcount <= len) {
memcpy(sl->rbuff, rbuff, sl->rcount);
} else {
sl->rcount = 0;
dev->stats.rx_over_errors++;
set_bit(SLF_ERROR, &sl->flags);
}
}
sl->mtu = mtu;
dev->mtu = mtu;
sl->buffsize = len;
err = 0;
done_on_bh:
spin_unlock_bh(&sl->lock);
done:
kfree(xbuff);
kfree(rbuff);
#ifdef SL_INCLUDE_CSLIP
kfree(cbuff);
#endif
return err;
}
/* Set the "sending" flag. This must be atomic hence the set_bit. */
static inline void sl_lock(struct slip *sl)
{
netif_stop_queue(sl->dev);
}
/* Clear the "sending" flag. This must be atomic, hence the ASM. */
static inline void sl_unlock(struct slip *sl)
{
netif_wake_queue(sl->dev);
}
/* Send one completely decapsulated IP datagram to the IP layer. */
static void sl_bump(struct slip *sl)
{
struct net_device *dev = sl->dev;
struct sk_buff *skb;
int count;
count = sl->rcount;
#ifdef SL_INCLUDE_CSLIP
if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) {
unsigned char c = sl->rbuff[0];
if (c & SL_TYPE_COMPRESSED_TCP) {
/* ignore compressed packets when CSLIP is off */
if (!(sl->mode & SL_MODE_CSLIP)) {
printk(KERN_WARNING "%s: compressed packet ignored\n", dev->name);
return;
}
/* make sure we've reserved enough space for uncompress
to use */
if (count + 80 > sl->buffsize) {
dev->stats.rx_over_errors++;
return;
}
count = slhc_uncompress(sl->slcomp, sl->rbuff, count);
if (count <= 0)
return;
} else if (c >= SL_TYPE_UNCOMPRESSED_TCP) {
if (!(sl->mode & SL_MODE_CSLIP)) {
/* turn on header compression */
sl->mode |= SL_MODE_CSLIP;
sl->mode &= ~SL_MODE_ADAPTIVE;
printk(KERN_INFO "%s: header compression turned on\n", dev->name);
}
sl->rbuff[0] &= 0x4f;
if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0)
return;
}
}
#endif /* SL_INCLUDE_CSLIP */
dev->stats.rx_bytes += count;
skb = dev_alloc_skb(count);
if (skb == NULL) {
printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", dev->name);
dev->stats.rx_dropped++;
return;
}
skb->dev = dev;
memcpy(skb_put(skb, count), sl->rbuff, count);
skb_reset_mac_header(skb);
skb->protocol = htons(ETH_P_IP);
netif_rx_ni(skb);
dev->stats.rx_packets++;
}
/* Encapsulate one IP datagram and stuff into a TTY queue. */
static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
{
unsigned char *p;
int actual, count;
if (len > sl->mtu) { /* Sigh, shouldn't occur BUT ... */
printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name);
sl->dev->stats.tx_dropped++;
sl_unlock(sl);
return;
}
p = icp;
#ifdef SL_INCLUDE_CSLIP
if (sl->mode & SL_MODE_CSLIP)
len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1);
#endif
#ifdef CONFIG_SLIP_MODE_SLIP6
if (sl->mode & SL_MODE_SLIP6)
count = slip_esc6(p, sl->xbuff, len);
else
#endif
count = slip_esc(p, sl->xbuff, len);
/* Order of next two lines is *very* important.
* When we are sending a little amount of data,
* the transfer may be completed inside the ops->write()
* routine, because it's running with interrupts enabled.
* In this case we *never* got WRITE_WAKEUP event,
* if we did not request it before write operation.
* 14 Oct 1994 Dmitry Gorodchanin.
*/
set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
#ifdef SL_CHECK_TRANSMIT
sl->dev->trans_start = jiffies;
#endif
sl->xleft = count - actual;
sl->xhead = sl->xbuff + actual;
#ifdef CONFIG_SLIP_SMART
/* VSV */
clear_bit(SLF_OUTWAIT, &sl->flags); /* reset outfill flag */
#endif
}
slip: Fix deadlock in write_wakeup Use schedule_work() to avoid potentially taking the spinlock in interrupt context. Commit cc9fa74e2a ("slip/slcan: added locking in wakeup function") added necessary locking to the wakeup function and 367525c8c2/ddcde142be ("can: slcan: Fix spinlock variant") converted it to spin_lock_bh() because the lock is also taken in timers. Disabling softirqs is not sufficient, however, as tty drivers may call write_wakeup from interrupt context. This driver calls tty->ops->write() with its spinlock held, which may immediately cause an interrupt on the same CPU and subsequent spin_bug(). Simply converting to spin_lock_irq/irqsave() prevents this deadlock, but causes lockdep to point out a possible circular locking dependency between these locks: (&(&sl->lock)->rlock){-.....}, at: slip_write_wakeup (&port_lock_key){-.....}, at: serial8250_handle_irq.part.13 The slip transmit is holding the slip spinlock when calling the tty write. This grabs the port lock. On an interrupt, the handler grabs the port lock and calls write_wakeup which grabs the slip lock. This could be a problem if a serial interrupt occurs on another CPU during the slip transmit. To deal with these issues, don't grab the lock in the wakeup function by deferring the writeout to a workqueue. Also hold the lock during close when de-assigning the tty pointer to safely disarm the worker and timers. This bug is easily reproducible on the first transmit when slip is used with the standard 8250 serial driver. [<c0410b7c>] (spin_bug+0x0/0x38) from [<c006109c>] (do_raw_spin_lock+0x60/0x1d0) r5:eab27000 r4:ec02754c [<c006103c>] (do_raw_spin_lock+0x0/0x1d0) from [<c04185c0>] (_raw_spin_lock+0x28/0x2c) r10:0000001f r9:eabb814c r8:eabb8140 r7:40070193 r6:ec02754c r5:eab27000 r4:ec02754c r3:00000000 [<c0418598>] (_raw_spin_lock+0x0/0x2c) from [<bf3a0220>] (slip_write_wakeup+0x50/0xe0 [slip]) r4:ec027540 r3:00000003 [<bf3a01d0>] (slip_write_wakeup+0x0/0xe0 [slip]) from [<c026e420>] (tty_wakeup+0x48/0x68) r6:00000000 r5:ea80c480 r4:eab27000 r3:bf3a01d0 [<c026e3d8>] (tty_wakeup+0x0/0x68) from [<c028a8ec>] (uart_write_wakeup+0x2c/0x30) r5:ed68ea90 r4:c06790d8 [<c028a8c0>] (uart_write_wakeup+0x0/0x30) from [<c028dc44>] (serial8250_tx_chars+0x114/0x170) [<c028db30>] (serial8250_tx_chars+0x0/0x170) from [<c028dffc>] (serial8250_handle_irq+0xa0/0xbc) r6:000000c2 r5:00000060 r4:c06790d8 r3:00000000 [<c028df5c>] (serial8250_handle_irq+0x0/0xbc) from [<c02933a4>] (dw8250_handle_irq+0x38/0x64) r7:00000000 r6:edd2f390 r5:000000c2 r4:c06790d8 [<c029336c>] (dw8250_handle_irq+0x0/0x64) from [<c028d2f4>] (serial8250_interrupt+0x44/0xc4) r6:00000000 r5:00000000 r4:c06791c4 r3:c029336c [<c028d2b0>] (serial8250_interrupt+0x0/0xc4) from [<c0067fe4>] (handle_irq_event_percpu+0xb4/0x2b0) r10:c06790d8 r9:eab27000 r8:00000000 r7:00000000 r6:0000001f r5:edd52980 r4:ec53b6c0 r3:c028d2b0 [<c0067f30>] (handle_irq_event_percpu+0x0/0x2b0) from [<c006822c>] (handle_irq_event+0x4c/0x6c) r10:c06790d8 r9:eab27000 r8:c0673ae0 r7:c05c2020 r6:ec53b6c0 r5:edd529d4 r4:edd52980 [<c00681e0>] (handle_irq_event+0x0/0x6c) from [<c006b140>] (handle_level_irq+0xe8/0x100) r6:00000000 r5:edd529d4 r4:edd52980 r3:00022000 [<c006b058>] (handle_level_irq+0x0/0x100) from [<c00676f8>] (generic_handle_irq+0x30/0x40) r5:0000001f r4:0000001f [<c00676c8>] (generic_handle_irq+0x0/0x40) from [<c000f57c>] (handle_IRQ+0xd0/0x13c) r4:ea997b18 r3:000000e0 [<c000f4ac>] (handle_IRQ+0x0/0x13c) from [<c00086c4>] (armada_370_xp_handle_irq+0x4c/0x118) r8:000003ff r7:ea997b18 r6:ffffffff r5:60070013 r4:c0674dc0 [<c0008678>] (armada_370_xp_handle_irq+0x0/0x118) from [<c0013840>] (__irq_svc+0x40/0x70) Exception stack(0xea997b18 to 0xea997b60) 7b00: 00000001 20070013 7b20: 00000000 0000000b 20070013 eab27000 20070013 00000000 ed10103e eab27000 7b40: c06790d8 ea997b74 ea997b60 ea997b60 c04186c0 c04186c8 60070013 ffffffff r9:eab27000 r8:ed10103e r7:ea997b4c r6:ffffffff r5:60070013 r4:c04186c8 [<c04186a4>] (_raw_spin_unlock_irqrestore+0x0/0x54) from [<c0288fc0>] (uart_start+0x40/0x44) r4:c06790d8 r3:c028ddd8 [<c0288f80>] (uart_start+0x0/0x44) from [<c028982c>] (uart_write+0xe4/0xf4) r6:0000003e r5:00000000 r4:ed68ea90 r3:0000003e [<c0289748>] (uart_write+0x0/0xf4) from [<bf3a0d20>] (sl_xmit+0x1c4/0x228 [slip]) r10:ed388e60 r9:0000003c r8:ffffffdd r7:0000003e r6:ec02754c r5:ea717eb8 r4:ec027000 [<bf3a0b5c>] (sl_xmit+0x0/0x228 [slip]) from [<c0368d74>] (dev_hard_start_xmit+0x39c/0x6d0) r8:eaf163c0 r7:ec027000 r6:ea717eb8 r5:00000000 r4:00000000 Signed-off-by: Tyler Hall <tylerwhall@gmail.com> Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: Andre Naujoks <nautsch2@gmail.com> Cc: David S. Miller <davem@davemloft.net> Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-16 09:23:16 +07:00
/* Write out any remaining transmit buffer. Scheduled when tty is writable */
static void slip_transmit(struct work_struct *work)
{
slip: Fix deadlock in write_wakeup Use schedule_work() to avoid potentially taking the spinlock in interrupt context. Commit cc9fa74e2a ("slip/slcan: added locking in wakeup function") added necessary locking to the wakeup function and 367525c8c2/ddcde142be ("can: slcan: Fix spinlock variant") converted it to spin_lock_bh() because the lock is also taken in timers. Disabling softirqs is not sufficient, however, as tty drivers may call write_wakeup from interrupt context. This driver calls tty->ops->write() with its spinlock held, which may immediately cause an interrupt on the same CPU and subsequent spin_bug(). Simply converting to spin_lock_irq/irqsave() prevents this deadlock, but causes lockdep to point out a possible circular locking dependency between these locks: (&(&sl->lock)->rlock){-.....}, at: slip_write_wakeup (&port_lock_key){-.....}, at: serial8250_handle_irq.part.13 The slip transmit is holding the slip spinlock when calling the tty write. This grabs the port lock. On an interrupt, the handler grabs the port lock and calls write_wakeup which grabs the slip lock. This could be a problem if a serial interrupt occurs on another CPU during the slip transmit. To deal with these issues, don't grab the lock in the wakeup function by deferring the writeout to a workqueue. Also hold the lock during close when de-assigning the tty pointer to safely disarm the worker and timers. This bug is easily reproducible on the first transmit when slip is used with the standard 8250 serial driver. [<c0410b7c>] (spin_bug+0x0/0x38) from [<c006109c>] (do_raw_spin_lock+0x60/0x1d0) r5:eab27000 r4:ec02754c [<c006103c>] (do_raw_spin_lock+0x0/0x1d0) from [<c04185c0>] (_raw_spin_lock+0x28/0x2c) r10:0000001f r9:eabb814c r8:eabb8140 r7:40070193 r6:ec02754c r5:eab27000 r4:ec02754c r3:00000000 [<c0418598>] (_raw_spin_lock+0x0/0x2c) from [<bf3a0220>] (slip_write_wakeup+0x50/0xe0 [slip]) r4:ec027540 r3:00000003 [<bf3a01d0>] (slip_write_wakeup+0x0/0xe0 [slip]) from [<c026e420>] (tty_wakeup+0x48/0x68) r6:00000000 r5:ea80c480 r4:eab27000 r3:bf3a01d0 [<c026e3d8>] (tty_wakeup+0x0/0x68) from [<c028a8ec>] (uart_write_wakeup+0x2c/0x30) r5:ed68ea90 r4:c06790d8 [<c028a8c0>] (uart_write_wakeup+0x0/0x30) from [<c028dc44>] (serial8250_tx_chars+0x114/0x170) [<c028db30>] (serial8250_tx_chars+0x0/0x170) from [<c028dffc>] (serial8250_handle_irq+0xa0/0xbc) r6:000000c2 r5:00000060 r4:c06790d8 r3:00000000 [<c028df5c>] (serial8250_handle_irq+0x0/0xbc) from [<c02933a4>] (dw8250_handle_irq+0x38/0x64) r7:00000000 r6:edd2f390 r5:000000c2 r4:c06790d8 [<c029336c>] (dw8250_handle_irq+0x0/0x64) from [<c028d2f4>] (serial8250_interrupt+0x44/0xc4) r6:00000000 r5:00000000 r4:c06791c4 r3:c029336c [<c028d2b0>] (serial8250_interrupt+0x0/0xc4) from [<c0067fe4>] (handle_irq_event_percpu+0xb4/0x2b0) r10:c06790d8 r9:eab27000 r8:00000000 r7:00000000 r6:0000001f r5:edd52980 r4:ec53b6c0 r3:c028d2b0 [<c0067f30>] (handle_irq_event_percpu+0x0/0x2b0) from [<c006822c>] (handle_irq_event+0x4c/0x6c) r10:c06790d8 r9:eab27000 r8:c0673ae0 r7:c05c2020 r6:ec53b6c0 r5:edd529d4 r4:edd52980 [<c00681e0>] (handle_irq_event+0x0/0x6c) from [<c006b140>] (handle_level_irq+0xe8/0x100) r6:00000000 r5:edd529d4 r4:edd52980 r3:00022000 [<c006b058>] (handle_level_irq+0x0/0x100) from [<c00676f8>] (generic_handle_irq+0x30/0x40) r5:0000001f r4:0000001f [<c00676c8>] (generic_handle_irq+0x0/0x40) from [<c000f57c>] (handle_IRQ+0xd0/0x13c) r4:ea997b18 r3:000000e0 [<c000f4ac>] (handle_IRQ+0x0/0x13c) from [<c00086c4>] (armada_370_xp_handle_irq+0x4c/0x118) r8:000003ff r7:ea997b18 r6:ffffffff r5:60070013 r4:c0674dc0 [<c0008678>] (armada_370_xp_handle_irq+0x0/0x118) from [<c0013840>] (__irq_svc+0x40/0x70) Exception stack(0xea997b18 to 0xea997b60) 7b00: 00000001 20070013 7b20: 00000000 0000000b 20070013 eab27000 20070013 00000000 ed10103e eab27000 7b40: c06790d8 ea997b74 ea997b60 ea997b60 c04186c0 c04186c8 60070013 ffffffff r9:eab27000 r8:ed10103e r7:ea997b4c r6:ffffffff r5:60070013 r4:c04186c8 [<c04186a4>] (_raw_spin_unlock_irqrestore+0x0/0x54) from [<c0288fc0>] (uart_start+0x40/0x44) r4:c06790d8 r3:c028ddd8 [<c0288f80>] (uart_start+0x0/0x44) from [<c028982c>] (uart_write+0xe4/0xf4) r6:0000003e r5:00000000 r4:ed68ea90 r3:0000003e [<c0289748>] (uart_write+0x0/0xf4) from [<bf3a0d20>] (sl_xmit+0x1c4/0x228 [slip]) r10:ed388e60 r9:0000003c r8:ffffffdd r7:0000003e r6:ec02754c r5:ea717eb8 r4:ec027000 [<bf3a0b5c>] (sl_xmit+0x0/0x228 [slip]) from [<c0368d74>] (dev_hard_start_xmit+0x39c/0x6d0) r8:eaf163c0 r7:ec027000 r6:ea717eb8 r5:00000000 r4:00000000 Signed-off-by: Tyler Hall <tylerwhall@gmail.com> Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: Andre Naujoks <nautsch2@gmail.com> Cc: David S. Miller <davem@davemloft.net> Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-16 09:23:16 +07:00
struct slip *sl = container_of(work, struct slip, tx_work);
int actual;
slip: Fix deadlock in write_wakeup Use schedule_work() to avoid potentially taking the spinlock in interrupt context. Commit cc9fa74e2a ("slip/slcan: added locking in wakeup function") added necessary locking to the wakeup function and 367525c8c2/ddcde142be ("can: slcan: Fix spinlock variant") converted it to spin_lock_bh() because the lock is also taken in timers. Disabling softirqs is not sufficient, however, as tty drivers may call write_wakeup from interrupt context. This driver calls tty->ops->write() with its spinlock held, which may immediately cause an interrupt on the same CPU and subsequent spin_bug(). Simply converting to spin_lock_irq/irqsave() prevents this deadlock, but causes lockdep to point out a possible circular locking dependency between these locks: (&(&sl->lock)->rlock){-.....}, at: slip_write_wakeup (&port_lock_key){-.....}, at: serial8250_handle_irq.part.13 The slip transmit is holding the slip spinlock when calling the tty write. This grabs the port lock. On an interrupt, the handler grabs the port lock and calls write_wakeup which grabs the slip lock. This could be a problem if a serial interrupt occurs on another CPU during the slip transmit. To deal with these issues, don't grab the lock in the wakeup function by deferring the writeout to a workqueue. Also hold the lock during close when de-assigning the tty pointer to safely disarm the worker and timers. This bug is easily reproducible on the first transmit when slip is used with the standard 8250 serial driver. [<c0410b7c>] (spin_bug+0x0/0x38) from [<c006109c>] (do_raw_spin_lock+0x60/0x1d0) r5:eab27000 r4:ec02754c [<c006103c>] (do_raw_spin_lock+0x0/0x1d0) from [<c04185c0>] (_raw_spin_lock+0x28/0x2c) r10:0000001f r9:eabb814c r8:eabb8140 r7:40070193 r6:ec02754c r5:eab27000 r4:ec02754c r3:00000000 [<c0418598>] (_raw_spin_lock+0x0/0x2c) from [<bf3a0220>] (slip_write_wakeup+0x50/0xe0 [slip]) r4:ec027540 r3:00000003 [<bf3a01d0>] (slip_write_wakeup+0x0/0xe0 [slip]) from [<c026e420>] (tty_wakeup+0x48/0x68) r6:00000000 r5:ea80c480 r4:eab27000 r3:bf3a01d0 [<c026e3d8>] (tty_wakeup+0x0/0x68) from [<c028a8ec>] (uart_write_wakeup+0x2c/0x30) r5:ed68ea90 r4:c06790d8 [<c028a8c0>] (uart_write_wakeup+0x0/0x30) from [<c028dc44>] (serial8250_tx_chars+0x114/0x170) [<c028db30>] (serial8250_tx_chars+0x0/0x170) from [<c028dffc>] (serial8250_handle_irq+0xa0/0xbc) r6:000000c2 r5:00000060 r4:c06790d8 r3:00000000 [<c028df5c>] (serial8250_handle_irq+0x0/0xbc) from [<c02933a4>] (dw8250_handle_irq+0x38/0x64) r7:00000000 r6:edd2f390 r5:000000c2 r4:c06790d8 [<c029336c>] (dw8250_handle_irq+0x0/0x64) from [<c028d2f4>] (serial8250_interrupt+0x44/0xc4) r6:00000000 r5:00000000 r4:c06791c4 r3:c029336c [<c028d2b0>] (serial8250_interrupt+0x0/0xc4) from [<c0067fe4>] (handle_irq_event_percpu+0xb4/0x2b0) r10:c06790d8 r9:eab27000 r8:00000000 r7:00000000 r6:0000001f r5:edd52980 r4:ec53b6c0 r3:c028d2b0 [<c0067f30>] (handle_irq_event_percpu+0x0/0x2b0) from [<c006822c>] (handle_irq_event+0x4c/0x6c) r10:c06790d8 r9:eab27000 r8:c0673ae0 r7:c05c2020 r6:ec53b6c0 r5:edd529d4 r4:edd52980 [<c00681e0>] (handle_irq_event+0x0/0x6c) from [<c006b140>] (handle_level_irq+0xe8/0x100) r6:00000000 r5:edd529d4 r4:edd52980 r3:00022000 [<c006b058>] (handle_level_irq+0x0/0x100) from [<c00676f8>] (generic_handle_irq+0x30/0x40) r5:0000001f r4:0000001f [<c00676c8>] (generic_handle_irq+0x0/0x40) from [<c000f57c>] (handle_IRQ+0xd0/0x13c) r4:ea997b18 r3:000000e0 [<c000f4ac>] (handle_IRQ+0x0/0x13c) from [<c00086c4>] (armada_370_xp_handle_irq+0x4c/0x118) r8:000003ff r7:ea997b18 r6:ffffffff r5:60070013 r4:c0674dc0 [<c0008678>] (armada_370_xp_handle_irq+0x0/0x118) from [<c0013840>] (__irq_svc+0x40/0x70) Exception stack(0xea997b18 to 0xea997b60) 7b00: 00000001 20070013 7b20: 00000000 0000000b 20070013 eab27000 20070013 00000000 ed10103e eab27000 7b40: c06790d8 ea997b74 ea997b60 ea997b60 c04186c0 c04186c8 60070013 ffffffff r9:eab27000 r8:ed10103e r7:ea997b4c r6:ffffffff r5:60070013 r4:c04186c8 [<c04186a4>] (_raw_spin_unlock_irqrestore+0x0/0x54) from [<c0288fc0>] (uart_start+0x40/0x44) r4:c06790d8 r3:c028ddd8 [<c0288f80>] (uart_start+0x0/0x44) from [<c028982c>] (uart_write+0xe4/0xf4) r6:0000003e r5:00000000 r4:ed68ea90 r3:0000003e [<c0289748>] (uart_write+0x0/0xf4) from [<bf3a0d20>] (sl_xmit+0x1c4/0x228 [slip]) r10:ed388e60 r9:0000003c r8:ffffffdd r7:0000003e r6:ec02754c r5:ea717eb8 r4:ec027000 [<bf3a0b5c>] (sl_xmit+0x0/0x228 [slip]) from [<c0368d74>] (dev_hard_start_xmit+0x39c/0x6d0) r8:eaf163c0 r7:ec027000 r6:ea717eb8 r5:00000000 r4:00000000 Signed-off-by: Tyler Hall <tylerwhall@gmail.com> Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: Andre Naujoks <nautsch2@gmail.com> Cc: David S. Miller <davem@davemloft.net> Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-16 09:23:16 +07:00
spin_lock_bh(&sl->lock);
/* First make sure we're connected. */
slip: Fix deadlock in write_wakeup Use schedule_work() to avoid potentially taking the spinlock in interrupt context. Commit cc9fa74e2a ("slip/slcan: added locking in wakeup function") added necessary locking to the wakeup function and 367525c8c2/ddcde142be ("can: slcan: Fix spinlock variant") converted it to spin_lock_bh() because the lock is also taken in timers. Disabling softirqs is not sufficient, however, as tty drivers may call write_wakeup from interrupt context. This driver calls tty->ops->write() with its spinlock held, which may immediately cause an interrupt on the same CPU and subsequent spin_bug(). Simply converting to spin_lock_irq/irqsave() prevents this deadlock, but causes lockdep to point out a possible circular locking dependency between these locks: (&(&sl->lock)->rlock){-.....}, at: slip_write_wakeup (&port_lock_key){-.....}, at: serial8250_handle_irq.part.13 The slip transmit is holding the slip spinlock when calling the tty write. This grabs the port lock. On an interrupt, the handler grabs the port lock and calls write_wakeup which grabs the slip lock. This could be a problem if a serial interrupt occurs on another CPU during the slip transmit. To deal with these issues, don't grab the lock in the wakeup function by deferring the writeout to a workqueue. Also hold the lock during close when de-assigning the tty pointer to safely disarm the worker and timers. This bug is easily reproducible on the first transmit when slip is used with the standard 8250 serial driver. [<c0410b7c>] (spin_bug+0x0/0x38) from [<c006109c>] (do_raw_spin_lock+0x60/0x1d0) r5:eab27000 r4:ec02754c [<c006103c>] (do_raw_spin_lock+0x0/0x1d0) from [<c04185c0>] (_raw_spin_lock+0x28/0x2c) r10:0000001f r9:eabb814c r8:eabb8140 r7:40070193 r6:ec02754c r5:eab27000 r4:ec02754c r3:00000000 [<c0418598>] (_raw_spin_lock+0x0/0x2c) from [<bf3a0220>] (slip_write_wakeup+0x50/0xe0 [slip]) r4:ec027540 r3:00000003 [<bf3a01d0>] (slip_write_wakeup+0x0/0xe0 [slip]) from [<c026e420>] (tty_wakeup+0x48/0x68) r6:00000000 r5:ea80c480 r4:eab27000 r3:bf3a01d0 [<c026e3d8>] (tty_wakeup+0x0/0x68) from [<c028a8ec>] (uart_write_wakeup+0x2c/0x30) r5:ed68ea90 r4:c06790d8 [<c028a8c0>] (uart_write_wakeup+0x0/0x30) from [<c028dc44>] (serial8250_tx_chars+0x114/0x170) [<c028db30>] (serial8250_tx_chars+0x0/0x170) from [<c028dffc>] (serial8250_handle_irq+0xa0/0xbc) r6:000000c2 r5:00000060 r4:c06790d8 r3:00000000 [<c028df5c>] (serial8250_handle_irq+0x0/0xbc) from [<c02933a4>] (dw8250_handle_irq+0x38/0x64) r7:00000000 r6:edd2f390 r5:000000c2 r4:c06790d8 [<c029336c>] (dw8250_handle_irq+0x0/0x64) from [<c028d2f4>] (serial8250_interrupt+0x44/0xc4) r6:00000000 r5:00000000 r4:c06791c4 r3:c029336c [<c028d2b0>] (serial8250_interrupt+0x0/0xc4) from [<c0067fe4>] (handle_irq_event_percpu+0xb4/0x2b0) r10:c06790d8 r9:eab27000 r8:00000000 r7:00000000 r6:0000001f r5:edd52980 r4:ec53b6c0 r3:c028d2b0 [<c0067f30>] (handle_irq_event_percpu+0x0/0x2b0) from [<c006822c>] (handle_irq_event+0x4c/0x6c) r10:c06790d8 r9:eab27000 r8:c0673ae0 r7:c05c2020 r6:ec53b6c0 r5:edd529d4 r4:edd52980 [<c00681e0>] (handle_irq_event+0x0/0x6c) from [<c006b140>] (handle_level_irq+0xe8/0x100) r6:00000000 r5:edd529d4 r4:edd52980 r3:00022000 [<c006b058>] (handle_level_irq+0x0/0x100) from [<c00676f8>] (generic_handle_irq+0x30/0x40) r5:0000001f r4:0000001f [<c00676c8>] (generic_handle_irq+0x0/0x40) from [<c000f57c>] (handle_IRQ+0xd0/0x13c) r4:ea997b18 r3:000000e0 [<c000f4ac>] (handle_IRQ+0x0/0x13c) from [<c00086c4>] (armada_370_xp_handle_irq+0x4c/0x118) r8:000003ff r7:ea997b18 r6:ffffffff r5:60070013 r4:c0674dc0 [<c0008678>] (armada_370_xp_handle_irq+0x0/0x118) from [<c0013840>] (__irq_svc+0x40/0x70) Exception stack(0xea997b18 to 0xea997b60) 7b00: 00000001 20070013 7b20: 00000000 0000000b 20070013 eab27000 20070013 00000000 ed10103e eab27000 7b40: c06790d8 ea997b74 ea997b60 ea997b60 c04186c0 c04186c8 60070013 ffffffff r9:eab27000 r8:ed10103e r7:ea997b4c r6:ffffffff r5:60070013 r4:c04186c8 [<c04186a4>] (_raw_spin_unlock_irqrestore+0x0/0x54) from [<c0288fc0>] (uart_start+0x40/0x44) r4:c06790d8 r3:c028ddd8 [<c0288f80>] (uart_start+0x0/0x44) from [<c028982c>] (uart_write+0xe4/0xf4) r6:0000003e r5:00000000 r4:ed68ea90 r3:0000003e [<c0289748>] (uart_write+0x0/0xf4) from [<bf3a0d20>] (sl_xmit+0x1c4/0x228 [slip]) r10:ed388e60 r9:0000003c r8:ffffffdd r7:0000003e r6:ec02754c r5:ea717eb8 r4:ec027000 [<bf3a0b5c>] (sl_xmit+0x0/0x228 [slip]) from [<c0368d74>] (dev_hard_start_xmit+0x39c/0x6d0) r8:eaf163c0 r7:ec027000 r6:ea717eb8 r5:00000000 r4:00000000 Signed-off-by: Tyler Hall <tylerwhall@gmail.com> Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: Andre Naujoks <nautsch2@gmail.com> Cc: David S. Miller <davem@davemloft.net> Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-16 09:23:16 +07:00
if (!sl->tty || sl->magic != SLIP_MAGIC || !netif_running(sl->dev)) {
spin_unlock_bh(&sl->lock);
return;
slip: Fix deadlock in write_wakeup Use schedule_work() to avoid potentially taking the spinlock in interrupt context. Commit cc9fa74e2a ("slip/slcan: added locking in wakeup function") added necessary locking to the wakeup function and 367525c8c2/ddcde142be ("can: slcan: Fix spinlock variant") converted it to spin_lock_bh() because the lock is also taken in timers. Disabling softirqs is not sufficient, however, as tty drivers may call write_wakeup from interrupt context. This driver calls tty->ops->write() with its spinlock held, which may immediately cause an interrupt on the same CPU and subsequent spin_bug(). Simply converting to spin_lock_irq/irqsave() prevents this deadlock, but causes lockdep to point out a possible circular locking dependency between these locks: (&(&sl->lock)->rlock){-.....}, at: slip_write_wakeup (&port_lock_key){-.....}, at: serial8250_handle_irq.part.13 The slip transmit is holding the slip spinlock when calling the tty write. This grabs the port lock. On an interrupt, the handler grabs the port lock and calls write_wakeup which grabs the slip lock. This could be a problem if a serial interrupt occurs on another CPU during the slip transmit. To deal with these issues, don't grab the lock in the wakeup function by deferring the writeout to a workqueue. Also hold the lock during close when de-assigning the tty pointer to safely disarm the worker and timers. This bug is easily reproducible on the first transmit when slip is used with the standard 8250 serial driver. [<c0410b7c>] (spin_bug+0x0/0x38) from [<c006109c>] (do_raw_spin_lock+0x60/0x1d0) r5:eab27000 r4:ec02754c [<c006103c>] (do_raw_spin_lock+0x0/0x1d0) from [<c04185c0>] (_raw_spin_lock+0x28/0x2c) r10:0000001f r9:eabb814c r8:eabb8140 r7:40070193 r6:ec02754c r5:eab27000 r4:ec02754c r3:00000000 [<c0418598>] (_raw_spin_lock+0x0/0x2c) from [<bf3a0220>] (slip_write_wakeup+0x50/0xe0 [slip]) r4:ec027540 r3:00000003 [<bf3a01d0>] (slip_write_wakeup+0x0/0xe0 [slip]) from [<c026e420>] (tty_wakeup+0x48/0x68) r6:00000000 r5:ea80c480 r4:eab27000 r3:bf3a01d0 [<c026e3d8>] (tty_wakeup+0x0/0x68) from [<c028a8ec>] (uart_write_wakeup+0x2c/0x30) r5:ed68ea90 r4:c06790d8 [<c028a8c0>] (uart_write_wakeup+0x0/0x30) from [<c028dc44>] (serial8250_tx_chars+0x114/0x170) [<c028db30>] (serial8250_tx_chars+0x0/0x170) from [<c028dffc>] (serial8250_handle_irq+0xa0/0xbc) r6:000000c2 r5:00000060 r4:c06790d8 r3:00000000 [<c028df5c>] (serial8250_handle_irq+0x0/0xbc) from [<c02933a4>] (dw8250_handle_irq+0x38/0x64) r7:00000000 r6:edd2f390 r5:000000c2 r4:c06790d8 [<c029336c>] (dw8250_handle_irq+0x0/0x64) from [<c028d2f4>] (serial8250_interrupt+0x44/0xc4) r6:00000000 r5:00000000 r4:c06791c4 r3:c029336c [<c028d2b0>] (serial8250_interrupt+0x0/0xc4) from [<c0067fe4>] (handle_irq_event_percpu+0xb4/0x2b0) r10:c06790d8 r9:eab27000 r8:00000000 r7:00000000 r6:0000001f r5:edd52980 r4:ec53b6c0 r3:c028d2b0 [<c0067f30>] (handle_irq_event_percpu+0x0/0x2b0) from [<c006822c>] (handle_irq_event+0x4c/0x6c) r10:c06790d8 r9:eab27000 r8:c0673ae0 r7:c05c2020 r6:ec53b6c0 r5:edd529d4 r4:edd52980 [<c00681e0>] (handle_irq_event+0x0/0x6c) from [<c006b140>] (handle_level_irq+0xe8/0x100) r6:00000000 r5:edd529d4 r4:edd52980 r3:00022000 [<c006b058>] (handle_level_irq+0x0/0x100) from [<c00676f8>] (generic_handle_irq+0x30/0x40) r5:0000001f r4:0000001f [<c00676c8>] (generic_handle_irq+0x0/0x40) from [<c000f57c>] (handle_IRQ+0xd0/0x13c) r4:ea997b18 r3:000000e0 [<c000f4ac>] (handle_IRQ+0x0/0x13c) from [<c00086c4>] (armada_370_xp_handle_irq+0x4c/0x118) r8:000003ff r7:ea997b18 r6:ffffffff r5:60070013 r4:c0674dc0 [<c0008678>] (armada_370_xp_handle_irq+0x0/0x118) from [<c0013840>] (__irq_svc+0x40/0x70) Exception stack(0xea997b18 to 0xea997b60) 7b00: 00000001 20070013 7b20: 00000000 0000000b 20070013 eab27000 20070013 00000000 ed10103e eab27000 7b40: c06790d8 ea997b74 ea997b60 ea997b60 c04186c0 c04186c8 60070013 ffffffff r9:eab27000 r8:ed10103e r7:ea997b4c r6:ffffffff r5:60070013 r4:c04186c8 [<c04186a4>] (_raw_spin_unlock_irqrestore+0x0/0x54) from [<c0288fc0>] (uart_start+0x40/0x44) r4:c06790d8 r3:c028ddd8 [<c0288f80>] (uart_start+0x0/0x44) from [<c028982c>] (uart_write+0xe4/0xf4) r6:0000003e r5:00000000 r4:ed68ea90 r3:0000003e [<c0289748>] (uart_write+0x0/0xf4) from [<bf3a0d20>] (sl_xmit+0x1c4/0x228 [slip]) r10:ed388e60 r9:0000003c r8:ffffffdd r7:0000003e r6:ec02754c r5:ea717eb8 r4:ec027000 [<bf3a0b5c>] (sl_xmit+0x0/0x228 [slip]) from [<c0368d74>] (dev_hard_start_xmit+0x39c/0x6d0) r8:eaf163c0 r7:ec027000 r6:ea717eb8 r5:00000000 r4:00000000 Signed-off-by: Tyler Hall <tylerwhall@gmail.com> Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: Andre Naujoks <nautsch2@gmail.com> Cc: David S. Miller <davem@davemloft.net> Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-16 09:23:16 +07:00
}
if (sl->xleft <= 0) {
/* Now serial buffer is almost free & we can start
* transmission of another packet */
sl->dev->stats.tx_packets++;
slip: Fix deadlock in write_wakeup Use schedule_work() to avoid potentially taking the spinlock in interrupt context. Commit cc9fa74e2a ("slip/slcan: added locking in wakeup function") added necessary locking to the wakeup function and 367525c8c2/ddcde142be ("can: slcan: Fix spinlock variant") converted it to spin_lock_bh() because the lock is also taken in timers. Disabling softirqs is not sufficient, however, as tty drivers may call write_wakeup from interrupt context. This driver calls tty->ops->write() with its spinlock held, which may immediately cause an interrupt on the same CPU and subsequent spin_bug(). Simply converting to spin_lock_irq/irqsave() prevents this deadlock, but causes lockdep to point out a possible circular locking dependency between these locks: (&(&sl->lock)->rlock){-.....}, at: slip_write_wakeup (&port_lock_key){-.....}, at: serial8250_handle_irq.part.13 The slip transmit is holding the slip spinlock when calling the tty write. This grabs the port lock. On an interrupt, the handler grabs the port lock and calls write_wakeup which grabs the slip lock. This could be a problem if a serial interrupt occurs on another CPU during the slip transmit. To deal with these issues, don't grab the lock in the wakeup function by deferring the writeout to a workqueue. Also hold the lock during close when de-assigning the tty pointer to safely disarm the worker and timers. This bug is easily reproducible on the first transmit when slip is used with the standard 8250 serial driver. [<c0410b7c>] (spin_bug+0x0/0x38) from [<c006109c>] (do_raw_spin_lock+0x60/0x1d0) r5:eab27000 r4:ec02754c [<c006103c>] (do_raw_spin_lock+0x0/0x1d0) from [<c04185c0>] (_raw_spin_lock+0x28/0x2c) r10:0000001f r9:eabb814c r8:eabb8140 r7:40070193 r6:ec02754c r5:eab27000 r4:ec02754c r3:00000000 [<c0418598>] (_raw_spin_lock+0x0/0x2c) from [<bf3a0220>] (slip_write_wakeup+0x50/0xe0 [slip]) r4:ec027540 r3:00000003 [<bf3a01d0>] (slip_write_wakeup+0x0/0xe0 [slip]) from [<c026e420>] (tty_wakeup+0x48/0x68) r6:00000000 r5:ea80c480 r4:eab27000 r3:bf3a01d0 [<c026e3d8>] (tty_wakeup+0x0/0x68) from [<c028a8ec>] (uart_write_wakeup+0x2c/0x30) r5:ed68ea90 r4:c06790d8 [<c028a8c0>] (uart_write_wakeup+0x0/0x30) from [<c028dc44>] (serial8250_tx_chars+0x114/0x170) [<c028db30>] (serial8250_tx_chars+0x0/0x170) from [<c028dffc>] (serial8250_handle_irq+0xa0/0xbc) r6:000000c2 r5:00000060 r4:c06790d8 r3:00000000 [<c028df5c>] (serial8250_handle_irq+0x0/0xbc) from [<c02933a4>] (dw8250_handle_irq+0x38/0x64) r7:00000000 r6:edd2f390 r5:000000c2 r4:c06790d8 [<c029336c>] (dw8250_handle_irq+0x0/0x64) from [<c028d2f4>] (serial8250_interrupt+0x44/0xc4) r6:00000000 r5:00000000 r4:c06791c4 r3:c029336c [<c028d2b0>] (serial8250_interrupt+0x0/0xc4) from [<c0067fe4>] (handle_irq_event_percpu+0xb4/0x2b0) r10:c06790d8 r9:eab27000 r8:00000000 r7:00000000 r6:0000001f r5:edd52980 r4:ec53b6c0 r3:c028d2b0 [<c0067f30>] (handle_irq_event_percpu+0x0/0x2b0) from [<c006822c>] (handle_irq_event+0x4c/0x6c) r10:c06790d8 r9:eab27000 r8:c0673ae0 r7:c05c2020 r6:ec53b6c0 r5:edd529d4 r4:edd52980 [<c00681e0>] (handle_irq_event+0x0/0x6c) from [<c006b140>] (handle_level_irq+0xe8/0x100) r6:00000000 r5:edd529d4 r4:edd52980 r3:00022000 [<c006b058>] (handle_level_irq+0x0/0x100) from [<c00676f8>] (generic_handle_irq+0x30/0x40) r5:0000001f r4:0000001f [<c00676c8>] (generic_handle_irq+0x0/0x40) from [<c000f57c>] (handle_IRQ+0xd0/0x13c) r4:ea997b18 r3:000000e0 [<c000f4ac>] (handle_IRQ+0x0/0x13c) from [<c00086c4>] (armada_370_xp_handle_irq+0x4c/0x118) r8:000003ff r7:ea997b18 r6:ffffffff r5:60070013 r4:c0674dc0 [<c0008678>] (armada_370_xp_handle_irq+0x0/0x118) from [<c0013840>] (__irq_svc+0x40/0x70) Exception stack(0xea997b18 to 0xea997b60) 7b00: 00000001 20070013 7b20: 00000000 0000000b 20070013 eab27000 20070013 00000000 ed10103e eab27000 7b40: c06790d8 ea997b74 ea997b60 ea997b60 c04186c0 c04186c8 60070013 ffffffff r9:eab27000 r8:ed10103e r7:ea997b4c r6:ffffffff r5:60070013 r4:c04186c8 [<c04186a4>] (_raw_spin_unlock_irqrestore+0x0/0x54) from [<c0288fc0>] (uart_start+0x40/0x44) r4:c06790d8 r3:c028ddd8 [<c0288f80>] (uart_start+0x0/0x44) from [<c028982c>] (uart_write+0xe4/0xf4) r6:0000003e r5:00000000 r4:ed68ea90 r3:0000003e [<c0289748>] (uart_write+0x0/0xf4) from [<bf3a0d20>] (sl_xmit+0x1c4/0x228 [slip]) r10:ed388e60 r9:0000003c r8:ffffffdd r7:0000003e r6:ec02754c r5:ea717eb8 r4:ec027000 [<bf3a0b5c>] (sl_xmit+0x0/0x228 [slip]) from [<c0368d74>] (dev_hard_start_xmit+0x39c/0x6d0) r8:eaf163c0 r7:ec027000 r6:ea717eb8 r5:00000000 r4:00000000 Signed-off-by: Tyler Hall <tylerwhall@gmail.com> Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: Andre Naujoks <nautsch2@gmail.com> Cc: David S. Miller <davem@davemloft.net> Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-16 09:23:16 +07:00
clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
spin_unlock_bh(&sl->lock);
sl_unlock(sl);
return;
}
slip: Fix deadlock in write_wakeup Use schedule_work() to avoid potentially taking the spinlock in interrupt context. Commit cc9fa74e2a ("slip/slcan: added locking in wakeup function") added necessary locking to the wakeup function and 367525c8c2/ddcde142be ("can: slcan: Fix spinlock variant") converted it to spin_lock_bh() because the lock is also taken in timers. Disabling softirqs is not sufficient, however, as tty drivers may call write_wakeup from interrupt context. This driver calls tty->ops->write() with its spinlock held, which may immediately cause an interrupt on the same CPU and subsequent spin_bug(). Simply converting to spin_lock_irq/irqsave() prevents this deadlock, but causes lockdep to point out a possible circular locking dependency between these locks: (&(&sl->lock)->rlock){-.....}, at: slip_write_wakeup (&port_lock_key){-.....}, at: serial8250_handle_irq.part.13 The slip transmit is holding the slip spinlock when calling the tty write. This grabs the port lock. On an interrupt, the handler grabs the port lock and calls write_wakeup which grabs the slip lock. This could be a problem if a serial interrupt occurs on another CPU during the slip transmit. To deal with these issues, don't grab the lock in the wakeup function by deferring the writeout to a workqueue. Also hold the lock during close when de-assigning the tty pointer to safely disarm the worker and timers. This bug is easily reproducible on the first transmit when slip is used with the standard 8250 serial driver. [<c0410b7c>] (spin_bug+0x0/0x38) from [<c006109c>] (do_raw_spin_lock+0x60/0x1d0) r5:eab27000 r4:ec02754c [<c006103c>] (do_raw_spin_lock+0x0/0x1d0) from [<c04185c0>] (_raw_spin_lock+0x28/0x2c) r10:0000001f r9:eabb814c r8:eabb8140 r7:40070193 r6:ec02754c r5:eab27000 r4:ec02754c r3:00000000 [<c0418598>] (_raw_spin_lock+0x0/0x2c) from [<bf3a0220>] (slip_write_wakeup+0x50/0xe0 [slip]) r4:ec027540 r3:00000003 [<bf3a01d0>] (slip_write_wakeup+0x0/0xe0 [slip]) from [<c026e420>] (tty_wakeup+0x48/0x68) r6:00000000 r5:ea80c480 r4:eab27000 r3:bf3a01d0 [<c026e3d8>] (tty_wakeup+0x0/0x68) from [<c028a8ec>] (uart_write_wakeup+0x2c/0x30) r5:ed68ea90 r4:c06790d8 [<c028a8c0>] (uart_write_wakeup+0x0/0x30) from [<c028dc44>] (serial8250_tx_chars+0x114/0x170) [<c028db30>] (serial8250_tx_chars+0x0/0x170) from [<c028dffc>] (serial8250_handle_irq+0xa0/0xbc) r6:000000c2 r5:00000060 r4:c06790d8 r3:00000000 [<c028df5c>] (serial8250_handle_irq+0x0/0xbc) from [<c02933a4>] (dw8250_handle_irq+0x38/0x64) r7:00000000 r6:edd2f390 r5:000000c2 r4:c06790d8 [<c029336c>] (dw8250_handle_irq+0x0/0x64) from [<c028d2f4>] (serial8250_interrupt+0x44/0xc4) r6:00000000 r5:00000000 r4:c06791c4 r3:c029336c [<c028d2b0>] (serial8250_interrupt+0x0/0xc4) from [<c0067fe4>] (handle_irq_event_percpu+0xb4/0x2b0) r10:c06790d8 r9:eab27000 r8:00000000 r7:00000000 r6:0000001f r5:edd52980 r4:ec53b6c0 r3:c028d2b0 [<c0067f30>] (handle_irq_event_percpu+0x0/0x2b0) from [<c006822c>] (handle_irq_event+0x4c/0x6c) r10:c06790d8 r9:eab27000 r8:c0673ae0 r7:c05c2020 r6:ec53b6c0 r5:edd529d4 r4:edd52980 [<c00681e0>] (handle_irq_event+0x0/0x6c) from [<c006b140>] (handle_level_irq+0xe8/0x100) r6:00000000 r5:edd529d4 r4:edd52980 r3:00022000 [<c006b058>] (handle_level_irq+0x0/0x100) from [<c00676f8>] (generic_handle_irq+0x30/0x40) r5:0000001f r4:0000001f [<c00676c8>] (generic_handle_irq+0x0/0x40) from [<c000f57c>] (handle_IRQ+0xd0/0x13c) r4:ea997b18 r3:000000e0 [<c000f4ac>] (handle_IRQ+0x0/0x13c) from [<c00086c4>] (armada_370_xp_handle_irq+0x4c/0x118) r8:000003ff r7:ea997b18 r6:ffffffff r5:60070013 r4:c0674dc0 [<c0008678>] (armada_370_xp_handle_irq+0x0/0x118) from [<c0013840>] (__irq_svc+0x40/0x70) Exception stack(0xea997b18 to 0xea997b60) 7b00: 00000001 20070013 7b20: 00000000 0000000b 20070013 eab27000 20070013 00000000 ed10103e eab27000 7b40: c06790d8 ea997b74 ea997b60 ea997b60 c04186c0 c04186c8 60070013 ffffffff r9:eab27000 r8:ed10103e r7:ea997b4c r6:ffffffff r5:60070013 r4:c04186c8 [<c04186a4>] (_raw_spin_unlock_irqrestore+0x0/0x54) from [<c0288fc0>] (uart_start+0x40/0x44) r4:c06790d8 r3:c028ddd8 [<c0288f80>] (uart_start+0x0/0x44) from [<c028982c>] (uart_write+0xe4/0xf4) r6:0000003e r5:00000000 r4:ed68ea90 r3:0000003e [<c0289748>] (uart_write+0x0/0xf4) from [<bf3a0d20>] (sl_xmit+0x1c4/0x228 [slip]) r10:ed388e60 r9:0000003c r8:ffffffdd r7:0000003e r6:ec02754c r5:ea717eb8 r4:ec027000 [<bf3a0b5c>] (sl_xmit+0x0/0x228 [slip]) from [<c0368d74>] (dev_hard_start_xmit+0x39c/0x6d0) r8:eaf163c0 r7:ec027000 r6:ea717eb8 r5:00000000 r4:00000000 Signed-off-by: Tyler Hall <tylerwhall@gmail.com> Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: Andre Naujoks <nautsch2@gmail.com> Cc: David S. Miller <davem@davemloft.net> Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-16 09:23:16 +07:00
actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
sl->xleft -= actual;
sl->xhead += actual;
spin_unlock_bh(&sl->lock);
}
slip: Fix deadlock in write_wakeup Use schedule_work() to avoid potentially taking the spinlock in interrupt context. Commit cc9fa74e2a ("slip/slcan: added locking in wakeup function") added necessary locking to the wakeup function and 367525c8c2/ddcde142be ("can: slcan: Fix spinlock variant") converted it to spin_lock_bh() because the lock is also taken in timers. Disabling softirqs is not sufficient, however, as tty drivers may call write_wakeup from interrupt context. This driver calls tty->ops->write() with its spinlock held, which may immediately cause an interrupt on the same CPU and subsequent spin_bug(). Simply converting to spin_lock_irq/irqsave() prevents this deadlock, but causes lockdep to point out a possible circular locking dependency between these locks: (&(&sl->lock)->rlock){-.....}, at: slip_write_wakeup (&port_lock_key){-.....}, at: serial8250_handle_irq.part.13 The slip transmit is holding the slip spinlock when calling the tty write. This grabs the port lock. On an interrupt, the handler grabs the port lock and calls write_wakeup which grabs the slip lock. This could be a problem if a serial interrupt occurs on another CPU during the slip transmit. To deal with these issues, don't grab the lock in the wakeup function by deferring the writeout to a workqueue. Also hold the lock during close when de-assigning the tty pointer to safely disarm the worker and timers. This bug is easily reproducible on the first transmit when slip is used with the standard 8250 serial driver. [<c0410b7c>] (spin_bug+0x0/0x38) from [<c006109c>] (do_raw_spin_lock+0x60/0x1d0) r5:eab27000 r4:ec02754c [<c006103c>] (do_raw_spin_lock+0x0/0x1d0) from [<c04185c0>] (_raw_spin_lock+0x28/0x2c) r10:0000001f r9:eabb814c r8:eabb8140 r7:40070193 r6:ec02754c r5:eab27000 r4:ec02754c r3:00000000 [<c0418598>] (_raw_spin_lock+0x0/0x2c) from [<bf3a0220>] (slip_write_wakeup+0x50/0xe0 [slip]) r4:ec027540 r3:00000003 [<bf3a01d0>] (slip_write_wakeup+0x0/0xe0 [slip]) from [<c026e420>] (tty_wakeup+0x48/0x68) r6:00000000 r5:ea80c480 r4:eab27000 r3:bf3a01d0 [<c026e3d8>] (tty_wakeup+0x0/0x68) from [<c028a8ec>] (uart_write_wakeup+0x2c/0x30) r5:ed68ea90 r4:c06790d8 [<c028a8c0>] (uart_write_wakeup+0x0/0x30) from [<c028dc44>] (serial8250_tx_chars+0x114/0x170) [<c028db30>] (serial8250_tx_chars+0x0/0x170) from [<c028dffc>] (serial8250_handle_irq+0xa0/0xbc) r6:000000c2 r5:00000060 r4:c06790d8 r3:00000000 [<c028df5c>] (serial8250_handle_irq+0x0/0xbc) from [<c02933a4>] (dw8250_handle_irq+0x38/0x64) r7:00000000 r6:edd2f390 r5:000000c2 r4:c06790d8 [<c029336c>] (dw8250_handle_irq+0x0/0x64) from [<c028d2f4>] (serial8250_interrupt+0x44/0xc4) r6:00000000 r5:00000000 r4:c06791c4 r3:c029336c [<c028d2b0>] (serial8250_interrupt+0x0/0xc4) from [<c0067fe4>] (handle_irq_event_percpu+0xb4/0x2b0) r10:c06790d8 r9:eab27000 r8:00000000 r7:00000000 r6:0000001f r5:edd52980 r4:ec53b6c0 r3:c028d2b0 [<c0067f30>] (handle_irq_event_percpu+0x0/0x2b0) from [<c006822c>] (handle_irq_event+0x4c/0x6c) r10:c06790d8 r9:eab27000 r8:c0673ae0 r7:c05c2020 r6:ec53b6c0 r5:edd529d4 r4:edd52980 [<c00681e0>] (handle_irq_event+0x0/0x6c) from [<c006b140>] (handle_level_irq+0xe8/0x100) r6:00000000 r5:edd529d4 r4:edd52980 r3:00022000 [<c006b058>] (handle_level_irq+0x0/0x100) from [<c00676f8>] (generic_handle_irq+0x30/0x40) r5:0000001f r4:0000001f [<c00676c8>] (generic_handle_irq+0x0/0x40) from [<c000f57c>] (handle_IRQ+0xd0/0x13c) r4:ea997b18 r3:000000e0 [<c000f4ac>] (handle_IRQ+0x0/0x13c) from [<c00086c4>] (armada_370_xp_handle_irq+0x4c/0x118) r8:000003ff r7:ea997b18 r6:ffffffff r5:60070013 r4:c0674dc0 [<c0008678>] (armada_370_xp_handle_irq+0x0/0x118) from [<c0013840>] (__irq_svc+0x40/0x70) Exception stack(0xea997b18 to 0xea997b60) 7b00: 00000001 20070013 7b20: 00000000 0000000b 20070013 eab27000 20070013 00000000 ed10103e eab27000 7b40: c06790d8 ea997b74 ea997b60 ea997b60 c04186c0 c04186c8 60070013 ffffffff r9:eab27000 r8:ed10103e r7:ea997b4c r6:ffffffff r5:60070013 r4:c04186c8 [<c04186a4>] (_raw_spin_unlock_irqrestore+0x0/0x54) from [<c0288fc0>] (uart_start+0x40/0x44) r4:c06790d8 r3:c028ddd8 [<c0288f80>] (uart_start+0x0/0x44) from [<c028982c>] (uart_write+0xe4/0xf4) r6:0000003e r5:00000000 r4:ed68ea90 r3:0000003e [<c0289748>] (uart_write+0x0/0xf4) from [<bf3a0d20>] (sl_xmit+0x1c4/0x228 [slip]) r10:ed388e60 r9:0000003c r8:ffffffdd r7:0000003e r6:ec02754c r5:ea717eb8 r4:ec027000 [<bf3a0b5c>] (sl_xmit+0x0/0x228 [slip]) from [<c0368d74>] (dev_hard_start_xmit+0x39c/0x6d0) r8:eaf163c0 r7:ec027000 r6:ea717eb8 r5:00000000 r4:00000000 Signed-off-by: Tyler Hall <tylerwhall@gmail.com> Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: Andre Naujoks <nautsch2@gmail.com> Cc: David S. Miller <davem@davemloft.net> Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-16 09:23:16 +07:00
/*
* Called by the driver when there's room for more data.
* Schedule the transmit.
*/
static void slip_write_wakeup(struct tty_struct *tty)
{
struct slip *sl = tty->disc_data;
schedule_work(&sl->tx_work);
}
static void sl_tx_timeout(struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
spin_lock(&sl->lock);
if (netif_queue_stopped(dev)) {
if (!netif_running(dev))
goto out;
/* May be we must check transmitter timeout here ?
* 14 Oct 1994 Dmitry Gorodchanin.
*/
#ifdef SL_CHECK_TRANSMIT
if (time_before(jiffies, dev_trans_start(dev) + 20 * HZ)) {
/* 20 sec timeout not reached */
goto out;
}
printk(KERN_WARNING "%s: transmit timed out, %s?\n",
dev->name,
(tty_chars_in_buffer(sl->tty) || sl->xleft) ?
"bad line quality" : "driver error");
sl->xleft = 0;
clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
sl_unlock(sl);
#endif
}
out:
spin_unlock(&sl->lock);
}
/* Encapsulate an IP datagram and kick it into a TTY queue. */
static netdev_tx_t
sl_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
spin_lock(&sl->lock);
if (!netif_running(dev)) {
spin_unlock(&sl->lock);
printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
if (sl->tty == NULL) {
spin_unlock(&sl->lock);
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
sl_lock(sl);
dev->stats.tx_bytes += skb->len;
sl_encaps(sl, skb->data, skb->len);
spin_unlock(&sl->lock);
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
/******************************************
* Routines looking at netdevice side.
******************************************/
/* Netdevice UP -> DOWN routine */
static int
sl_close(struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
spin_lock_bh(&sl->lock);
if (sl->tty)
/* TTY discipline is running. */
clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
netif_stop_queue(dev);
sl->rcount = 0;
sl->xleft = 0;
spin_unlock_bh(&sl->lock);
return 0;
}
/* Netdevice DOWN -> UP routine */
static int sl_open(struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
if (sl->tty == NULL)
return -ENODEV;
sl->flags &= (1 << SLF_INUSE);
netif_start_queue(dev);
return 0;
}
/* Netdevice change MTU request */
static int sl_change_mtu(struct net_device *dev, int new_mtu)
{
struct slip *sl = netdev_priv(dev);
if (new_mtu < 68 || new_mtu > 65534)
return -EINVAL;
if (new_mtu != dev->mtu)
return sl_realloc_bufs(sl, new_mtu);
return 0;
}
/* Netdevice get statistics request */
static struct rtnl_link_stats64 *
sl_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
{
struct net_device_stats *devstats = &dev->stats;
#ifdef SL_INCLUDE_CSLIP
struct slip *sl = netdev_priv(dev);
struct slcompress *comp = sl->slcomp;
#endif
stats->rx_packets = devstats->rx_packets;
stats->tx_packets = devstats->tx_packets;
stats->rx_bytes = devstats->rx_bytes;
stats->tx_bytes = devstats->tx_bytes;
stats->rx_dropped = devstats->rx_dropped;
stats->tx_dropped = devstats->tx_dropped;
stats->tx_errors = devstats->tx_errors;
stats->rx_errors = devstats->rx_errors;
stats->rx_over_errors = devstats->rx_over_errors;
#ifdef SL_INCLUDE_CSLIP
if (comp) {
/* Generic compressed statistics */
stats->rx_compressed = comp->sls_i_compressed;
stats->tx_compressed = comp->sls_o_compressed;
/* Are we really still needs this? */
stats->rx_fifo_errors += comp->sls_i_compressed;
stats->rx_dropped += comp->sls_i_tossed;
stats->tx_fifo_errors += comp->sls_o_compressed;
stats->collisions += comp->sls_o_misses;
}
#endif
return stats;
}
/* Netdevice register callback */
static int sl_init(struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
/*
* Finish setting up the DEVICE info.
*/
dev->mtu = sl->mtu;
dev->type = ARPHRD_SLIP + sl->mode;
#ifdef SL_CHECK_TRANSMIT
dev->watchdog_timeo = 20*HZ;
#endif
return 0;
}
static void sl_uninit(struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
sl_free_bufs(sl);
}
/* Hook the destructor so we can free slip devices at the right point in time */
static void sl_free_netdev(struct net_device *dev)
{
int i = dev->base_addr;
free_netdev(dev);
slip_devs[i] = NULL;
}
static const struct net_device_ops sl_netdev_ops = {
.ndo_init = sl_init,
.ndo_uninit = sl_uninit,
.ndo_open = sl_open,
.ndo_stop = sl_close,
.ndo_start_xmit = sl_xmit,
.ndo_get_stats64 = sl_get_stats64,
.ndo_change_mtu = sl_change_mtu,
.ndo_tx_timeout = sl_tx_timeout,
#ifdef CONFIG_SLIP_SMART
.ndo_do_ioctl = sl_ioctl,
#endif
};
static void sl_setup(struct net_device *dev)
{
dev->netdev_ops = &sl_netdev_ops;
dev->destructor = sl_free_netdev;
dev->hard_header_len = 0;
dev->addr_len = 0;
dev->tx_queue_len = 10;
/* New-style flags. */
dev->flags = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST;
}
/******************************************
Routines looking at TTY side.
******************************************/
/*
* Handle the 'receiver data ready' interrupt.
* This function is called by the 'tty_io' module in the kernel when
* a block of SLIP data has been received, which can now be decapsulated
* and sent on to some IP layer for further processing. This will not
* be re-entered while running but other ldisc functions may be called
* in parallel
*/
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>
2011-06-04 04:33:24 +07:00
static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
char *fp, int count)
{
struct slip *sl = tty->disc_data;
if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
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>
2011-06-04 04:33:24 +07:00
return;
/* 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>
2011-06-04 04:33:24 +07:00
while (count--) {
if (fp && *fp++) {
if (!test_and_set_bit(SLF_ERROR, &sl->flags))
sl->dev->stats.rx_errors++;
cp++;
continue;
}
#ifdef CONFIG_SLIP_MODE_SLIP6
if (sl->mode & SL_MODE_SLIP6)
slip_unesc6(sl, *cp++);
else
#endif
slip_unesc(sl, *cp++);
}
}
/************************************
* slip_open helper routines.
************************************/
/* Collect hanged up channels */
static void sl_sync(void)
{
int i;
struct net_device *dev;
struct slip *sl;
for (i = 0; i < slip_maxdev; i++) {
dev = slip_devs[i];
if (dev == NULL)
break;
sl = netdev_priv(dev);
if (sl->tty || sl->leased)
continue;
if (dev->flags & IFF_UP)
dev_close(dev);
}
}
/* Find a free SLIP channel, and link in this `tty' line. */
static struct slip *sl_alloc(dev_t line)
{
int i;
char name[IFNAMSIZ];
struct net_device *dev = NULL;
struct slip *sl;
for (i = 0; i < slip_maxdev; i++) {
dev = slip_devs[i];
if (dev == NULL)
break;
}
/* Sorry, too many, all slots in use */
if (i >= slip_maxdev)
return NULL;
sprintf(name, "sl%d", i);
dev = alloc_netdev(sizeof(*sl), name, NET_NAME_UNKNOWN, sl_setup);
if (!dev)
return NULL;
dev->base_addr = i;
sl = netdev_priv(dev);
/* Initialize channel control data */
sl->magic = SLIP_MAGIC;
sl->dev = dev;
spin_lock_init(&sl->lock);
slip: Fix deadlock in write_wakeup Use schedule_work() to avoid potentially taking the spinlock in interrupt context. Commit cc9fa74e2a ("slip/slcan: added locking in wakeup function") added necessary locking to the wakeup function and 367525c8c2/ddcde142be ("can: slcan: Fix spinlock variant") converted it to spin_lock_bh() because the lock is also taken in timers. Disabling softirqs is not sufficient, however, as tty drivers may call write_wakeup from interrupt context. This driver calls tty->ops->write() with its spinlock held, which may immediately cause an interrupt on the same CPU and subsequent spin_bug(). Simply converting to spin_lock_irq/irqsave() prevents this deadlock, but causes lockdep to point out a possible circular locking dependency between these locks: (&(&sl->lock)->rlock){-.....}, at: slip_write_wakeup (&port_lock_key){-.....}, at: serial8250_handle_irq.part.13 The slip transmit is holding the slip spinlock when calling the tty write. This grabs the port lock. On an interrupt, the handler grabs the port lock and calls write_wakeup which grabs the slip lock. This could be a problem if a serial interrupt occurs on another CPU during the slip transmit. To deal with these issues, don't grab the lock in the wakeup function by deferring the writeout to a workqueue. Also hold the lock during close when de-assigning the tty pointer to safely disarm the worker and timers. This bug is easily reproducible on the first transmit when slip is used with the standard 8250 serial driver. [<c0410b7c>] (spin_bug+0x0/0x38) from [<c006109c>] (do_raw_spin_lock+0x60/0x1d0) r5:eab27000 r4:ec02754c [<c006103c>] (do_raw_spin_lock+0x0/0x1d0) from [<c04185c0>] (_raw_spin_lock+0x28/0x2c) r10:0000001f r9:eabb814c r8:eabb8140 r7:40070193 r6:ec02754c r5:eab27000 r4:ec02754c r3:00000000 [<c0418598>] (_raw_spin_lock+0x0/0x2c) from [<bf3a0220>] (slip_write_wakeup+0x50/0xe0 [slip]) r4:ec027540 r3:00000003 [<bf3a01d0>] (slip_write_wakeup+0x0/0xe0 [slip]) from [<c026e420>] (tty_wakeup+0x48/0x68) r6:00000000 r5:ea80c480 r4:eab27000 r3:bf3a01d0 [<c026e3d8>] (tty_wakeup+0x0/0x68) from [<c028a8ec>] (uart_write_wakeup+0x2c/0x30) r5:ed68ea90 r4:c06790d8 [<c028a8c0>] (uart_write_wakeup+0x0/0x30) from [<c028dc44>] (serial8250_tx_chars+0x114/0x170) [<c028db30>] (serial8250_tx_chars+0x0/0x170) from [<c028dffc>] (serial8250_handle_irq+0xa0/0xbc) r6:000000c2 r5:00000060 r4:c06790d8 r3:00000000 [<c028df5c>] (serial8250_handle_irq+0x0/0xbc) from [<c02933a4>] (dw8250_handle_irq+0x38/0x64) r7:00000000 r6:edd2f390 r5:000000c2 r4:c06790d8 [<c029336c>] (dw8250_handle_irq+0x0/0x64) from [<c028d2f4>] (serial8250_interrupt+0x44/0xc4) r6:00000000 r5:00000000 r4:c06791c4 r3:c029336c [<c028d2b0>] (serial8250_interrupt+0x0/0xc4) from [<c0067fe4>] (handle_irq_event_percpu+0xb4/0x2b0) r10:c06790d8 r9:eab27000 r8:00000000 r7:00000000 r6:0000001f r5:edd52980 r4:ec53b6c0 r3:c028d2b0 [<c0067f30>] (handle_irq_event_percpu+0x0/0x2b0) from [<c006822c>] (handle_irq_event+0x4c/0x6c) r10:c06790d8 r9:eab27000 r8:c0673ae0 r7:c05c2020 r6:ec53b6c0 r5:edd529d4 r4:edd52980 [<c00681e0>] (handle_irq_event+0x0/0x6c) from [<c006b140>] (handle_level_irq+0xe8/0x100) r6:00000000 r5:edd529d4 r4:edd52980 r3:00022000 [<c006b058>] (handle_level_irq+0x0/0x100) from [<c00676f8>] (generic_handle_irq+0x30/0x40) r5:0000001f r4:0000001f [<c00676c8>] (generic_handle_irq+0x0/0x40) from [<c000f57c>] (handle_IRQ+0xd0/0x13c) r4:ea997b18 r3:000000e0 [<c000f4ac>] (handle_IRQ+0x0/0x13c) from [<c00086c4>] (armada_370_xp_handle_irq+0x4c/0x118) r8:000003ff r7:ea997b18 r6:ffffffff r5:60070013 r4:c0674dc0 [<c0008678>] (armada_370_xp_handle_irq+0x0/0x118) from [<c0013840>] (__irq_svc+0x40/0x70) Exception stack(0xea997b18 to 0xea997b60) 7b00: 00000001 20070013 7b20: 00000000 0000000b 20070013 eab27000 20070013 00000000 ed10103e eab27000 7b40: c06790d8 ea997b74 ea997b60 ea997b60 c04186c0 c04186c8 60070013 ffffffff r9:eab27000 r8:ed10103e r7:ea997b4c r6:ffffffff r5:60070013 r4:c04186c8 [<c04186a4>] (_raw_spin_unlock_irqrestore+0x0/0x54) from [<c0288fc0>] (uart_start+0x40/0x44) r4:c06790d8 r3:c028ddd8 [<c0288f80>] (uart_start+0x0/0x44) from [<c028982c>] (uart_write+0xe4/0xf4) r6:0000003e r5:00000000 r4:ed68ea90 r3:0000003e [<c0289748>] (uart_write+0x0/0xf4) from [<bf3a0d20>] (sl_xmit+0x1c4/0x228 [slip]) r10:ed388e60 r9:0000003c r8:ffffffdd r7:0000003e r6:ec02754c r5:ea717eb8 r4:ec027000 [<bf3a0b5c>] (sl_xmit+0x0/0x228 [slip]) from [<c0368d74>] (dev_hard_start_xmit+0x39c/0x6d0) r8:eaf163c0 r7:ec027000 r6:ea717eb8 r5:00000000 r4:00000000 Signed-off-by: Tyler Hall <tylerwhall@gmail.com> Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: Andre Naujoks <nautsch2@gmail.com> Cc: David S. Miller <davem@davemloft.net> Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-16 09:23:16 +07:00
INIT_WORK(&sl->tx_work, slip_transmit);
sl->mode = SL_MODE_DEFAULT;
#ifdef CONFIG_SLIP_SMART
/* initialize timer_list struct */
init_timer(&sl->keepalive_timer);
sl->keepalive_timer.data = (unsigned long)sl;
sl->keepalive_timer.function = sl_keepalive;
init_timer(&sl->outfill_timer);
sl->outfill_timer.data = (unsigned long)sl;
sl->outfill_timer.function = sl_outfill;
#endif
slip_devs[i] = dev;
return sl;
}
/*
* Open the high-level part of the SLIP channel.
* This function is called by the TTY module when the
* SLIP line discipline is called for. Because we are
* sure the tty line exists, we only have to link it to
* a free SLIP channel...
*
* Called in process context serialized from other ldisc calls.
*/
static int slip_open(struct tty_struct *tty)
{
struct slip *sl;
int err;
if (!capable(CAP_NET_ADMIN))
return -EPERM;
if (tty->ops->write == NULL)
return -EOPNOTSUPP;
/* RTnetlink lock is misused here to serialize concurrent
opens of slip channels. There are better ways, but it is
the simplest one.
*/
rtnl_lock();
/* Collect hanged up channels. */
sl_sync();
sl = tty->disc_data;
err = -EEXIST;
/* First make sure we're not already connected. */
if (sl && sl->magic == SLIP_MAGIC)
goto err_exit;
/* OK. Find a free SLIP channel to use. */
err = -ENFILE;
sl = sl_alloc(tty_devnum(tty));
if (sl == NULL)
goto err_exit;
sl->tty = tty;
tty->disc_data = sl;
sl->pid = current->pid;
if (!test_bit(SLF_INUSE, &sl->flags)) {
/* Perform the low-level SLIP initialization. */
err = sl_alloc_bufs(sl, SL_MTU);
if (err)
goto err_free_chan;
set_bit(SLF_INUSE, &sl->flags);
err = register_netdevice(sl->dev);
if (err)
goto err_free_bufs;
}
#ifdef CONFIG_SLIP_SMART
if (sl->keepalive) {
sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ;
add_timer(&sl->keepalive_timer);
}
if (sl->outfill) {
sl->outfill_timer.expires = jiffies + sl->outfill * HZ;
add_timer(&sl->outfill_timer);
}
#endif
/* Done. We have linked the TTY line to a channel. */
rtnl_unlock();
[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 11:54:13 +07:00
tty->receive_room = 65536; /* We don't flow control */
/* TTY layer expects 0 on success */
return 0;
err_free_bufs:
sl_free_bufs(sl);
err_free_chan:
sl->tty = NULL;
tty->disc_data = NULL;
clear_bit(SLF_INUSE, &sl->flags);
err_exit:
rtnl_unlock();
/* Count references from TTY module */
return err;
}
/*
* Close down a SLIP channel.
* This means flushing out any pending queues, and then returning. This
* call is serialized against other ldisc functions.
*
* We also use this method fo a hangup event
*/
static void slip_close(struct tty_struct *tty)
{
struct slip *sl = tty->disc_data;
/* First make sure we're connected. */
if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
return;
slip: Fix deadlock in write_wakeup Use schedule_work() to avoid potentially taking the spinlock in interrupt context. Commit cc9fa74e2a ("slip/slcan: added locking in wakeup function") added necessary locking to the wakeup function and 367525c8c2/ddcde142be ("can: slcan: Fix spinlock variant") converted it to spin_lock_bh() because the lock is also taken in timers. Disabling softirqs is not sufficient, however, as tty drivers may call write_wakeup from interrupt context. This driver calls tty->ops->write() with its spinlock held, which may immediately cause an interrupt on the same CPU and subsequent spin_bug(). Simply converting to spin_lock_irq/irqsave() prevents this deadlock, but causes lockdep to point out a possible circular locking dependency between these locks: (&(&sl->lock)->rlock){-.....}, at: slip_write_wakeup (&port_lock_key){-.....}, at: serial8250_handle_irq.part.13 The slip transmit is holding the slip spinlock when calling the tty write. This grabs the port lock. On an interrupt, the handler grabs the port lock and calls write_wakeup which grabs the slip lock. This could be a problem if a serial interrupt occurs on another CPU during the slip transmit. To deal with these issues, don't grab the lock in the wakeup function by deferring the writeout to a workqueue. Also hold the lock during close when de-assigning the tty pointer to safely disarm the worker and timers. This bug is easily reproducible on the first transmit when slip is used with the standard 8250 serial driver. [<c0410b7c>] (spin_bug+0x0/0x38) from [<c006109c>] (do_raw_spin_lock+0x60/0x1d0) r5:eab27000 r4:ec02754c [<c006103c>] (do_raw_spin_lock+0x0/0x1d0) from [<c04185c0>] (_raw_spin_lock+0x28/0x2c) r10:0000001f r9:eabb814c r8:eabb8140 r7:40070193 r6:ec02754c r5:eab27000 r4:ec02754c r3:00000000 [<c0418598>] (_raw_spin_lock+0x0/0x2c) from [<bf3a0220>] (slip_write_wakeup+0x50/0xe0 [slip]) r4:ec027540 r3:00000003 [<bf3a01d0>] (slip_write_wakeup+0x0/0xe0 [slip]) from [<c026e420>] (tty_wakeup+0x48/0x68) r6:00000000 r5:ea80c480 r4:eab27000 r3:bf3a01d0 [<c026e3d8>] (tty_wakeup+0x0/0x68) from [<c028a8ec>] (uart_write_wakeup+0x2c/0x30) r5:ed68ea90 r4:c06790d8 [<c028a8c0>] (uart_write_wakeup+0x0/0x30) from [<c028dc44>] (serial8250_tx_chars+0x114/0x170) [<c028db30>] (serial8250_tx_chars+0x0/0x170) from [<c028dffc>] (serial8250_handle_irq+0xa0/0xbc) r6:000000c2 r5:00000060 r4:c06790d8 r3:00000000 [<c028df5c>] (serial8250_handle_irq+0x0/0xbc) from [<c02933a4>] (dw8250_handle_irq+0x38/0x64) r7:00000000 r6:edd2f390 r5:000000c2 r4:c06790d8 [<c029336c>] (dw8250_handle_irq+0x0/0x64) from [<c028d2f4>] (serial8250_interrupt+0x44/0xc4) r6:00000000 r5:00000000 r4:c06791c4 r3:c029336c [<c028d2b0>] (serial8250_interrupt+0x0/0xc4) from [<c0067fe4>] (handle_irq_event_percpu+0xb4/0x2b0) r10:c06790d8 r9:eab27000 r8:00000000 r7:00000000 r6:0000001f r5:edd52980 r4:ec53b6c0 r3:c028d2b0 [<c0067f30>] (handle_irq_event_percpu+0x0/0x2b0) from [<c006822c>] (handle_irq_event+0x4c/0x6c) r10:c06790d8 r9:eab27000 r8:c0673ae0 r7:c05c2020 r6:ec53b6c0 r5:edd529d4 r4:edd52980 [<c00681e0>] (handle_irq_event+0x0/0x6c) from [<c006b140>] (handle_level_irq+0xe8/0x100) r6:00000000 r5:edd529d4 r4:edd52980 r3:00022000 [<c006b058>] (handle_level_irq+0x0/0x100) from [<c00676f8>] (generic_handle_irq+0x30/0x40) r5:0000001f r4:0000001f [<c00676c8>] (generic_handle_irq+0x0/0x40) from [<c000f57c>] (handle_IRQ+0xd0/0x13c) r4:ea997b18 r3:000000e0 [<c000f4ac>] (handle_IRQ+0x0/0x13c) from [<c00086c4>] (armada_370_xp_handle_irq+0x4c/0x118) r8:000003ff r7:ea997b18 r6:ffffffff r5:60070013 r4:c0674dc0 [<c0008678>] (armada_370_xp_handle_irq+0x0/0x118) from [<c0013840>] (__irq_svc+0x40/0x70) Exception stack(0xea997b18 to 0xea997b60) 7b00: 00000001 20070013 7b20: 00000000 0000000b 20070013 eab27000 20070013 00000000 ed10103e eab27000 7b40: c06790d8 ea997b74 ea997b60 ea997b60 c04186c0 c04186c8 60070013 ffffffff r9:eab27000 r8:ed10103e r7:ea997b4c r6:ffffffff r5:60070013 r4:c04186c8 [<c04186a4>] (_raw_spin_unlock_irqrestore+0x0/0x54) from [<c0288fc0>] (uart_start+0x40/0x44) r4:c06790d8 r3:c028ddd8 [<c0288f80>] (uart_start+0x0/0x44) from [<c028982c>] (uart_write+0xe4/0xf4) r6:0000003e r5:00000000 r4:ed68ea90 r3:0000003e [<c0289748>] (uart_write+0x0/0xf4) from [<bf3a0d20>] (sl_xmit+0x1c4/0x228 [slip]) r10:ed388e60 r9:0000003c r8:ffffffdd r7:0000003e r6:ec02754c r5:ea717eb8 r4:ec027000 [<bf3a0b5c>] (sl_xmit+0x0/0x228 [slip]) from [<c0368d74>] (dev_hard_start_xmit+0x39c/0x6d0) r8:eaf163c0 r7:ec027000 r6:ea717eb8 r5:00000000 r4:00000000 Signed-off-by: Tyler Hall <tylerwhall@gmail.com> Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: Andre Naujoks <nautsch2@gmail.com> Cc: David S. Miller <davem@davemloft.net> Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-16 09:23:16 +07:00
spin_lock_bh(&sl->lock);
tty->disc_data = NULL;
sl->tty = NULL;
slip: Fix deadlock in write_wakeup Use schedule_work() to avoid potentially taking the spinlock in interrupt context. Commit cc9fa74e2a ("slip/slcan: added locking in wakeup function") added necessary locking to the wakeup function and 367525c8c2/ddcde142be ("can: slcan: Fix spinlock variant") converted it to spin_lock_bh() because the lock is also taken in timers. Disabling softirqs is not sufficient, however, as tty drivers may call write_wakeup from interrupt context. This driver calls tty->ops->write() with its spinlock held, which may immediately cause an interrupt on the same CPU and subsequent spin_bug(). Simply converting to spin_lock_irq/irqsave() prevents this deadlock, but causes lockdep to point out a possible circular locking dependency between these locks: (&(&sl->lock)->rlock){-.....}, at: slip_write_wakeup (&port_lock_key){-.....}, at: serial8250_handle_irq.part.13 The slip transmit is holding the slip spinlock when calling the tty write. This grabs the port lock. On an interrupt, the handler grabs the port lock and calls write_wakeup which grabs the slip lock. This could be a problem if a serial interrupt occurs on another CPU during the slip transmit. To deal with these issues, don't grab the lock in the wakeup function by deferring the writeout to a workqueue. Also hold the lock during close when de-assigning the tty pointer to safely disarm the worker and timers. This bug is easily reproducible on the first transmit when slip is used with the standard 8250 serial driver. [<c0410b7c>] (spin_bug+0x0/0x38) from [<c006109c>] (do_raw_spin_lock+0x60/0x1d0) r5:eab27000 r4:ec02754c [<c006103c>] (do_raw_spin_lock+0x0/0x1d0) from [<c04185c0>] (_raw_spin_lock+0x28/0x2c) r10:0000001f r9:eabb814c r8:eabb8140 r7:40070193 r6:ec02754c r5:eab27000 r4:ec02754c r3:00000000 [<c0418598>] (_raw_spin_lock+0x0/0x2c) from [<bf3a0220>] (slip_write_wakeup+0x50/0xe0 [slip]) r4:ec027540 r3:00000003 [<bf3a01d0>] (slip_write_wakeup+0x0/0xe0 [slip]) from [<c026e420>] (tty_wakeup+0x48/0x68) r6:00000000 r5:ea80c480 r4:eab27000 r3:bf3a01d0 [<c026e3d8>] (tty_wakeup+0x0/0x68) from [<c028a8ec>] (uart_write_wakeup+0x2c/0x30) r5:ed68ea90 r4:c06790d8 [<c028a8c0>] (uart_write_wakeup+0x0/0x30) from [<c028dc44>] (serial8250_tx_chars+0x114/0x170) [<c028db30>] (serial8250_tx_chars+0x0/0x170) from [<c028dffc>] (serial8250_handle_irq+0xa0/0xbc) r6:000000c2 r5:00000060 r4:c06790d8 r3:00000000 [<c028df5c>] (serial8250_handle_irq+0x0/0xbc) from [<c02933a4>] (dw8250_handle_irq+0x38/0x64) r7:00000000 r6:edd2f390 r5:000000c2 r4:c06790d8 [<c029336c>] (dw8250_handle_irq+0x0/0x64) from [<c028d2f4>] (serial8250_interrupt+0x44/0xc4) r6:00000000 r5:00000000 r4:c06791c4 r3:c029336c [<c028d2b0>] (serial8250_interrupt+0x0/0xc4) from [<c0067fe4>] (handle_irq_event_percpu+0xb4/0x2b0) r10:c06790d8 r9:eab27000 r8:00000000 r7:00000000 r6:0000001f r5:edd52980 r4:ec53b6c0 r3:c028d2b0 [<c0067f30>] (handle_irq_event_percpu+0x0/0x2b0) from [<c006822c>] (handle_irq_event+0x4c/0x6c) r10:c06790d8 r9:eab27000 r8:c0673ae0 r7:c05c2020 r6:ec53b6c0 r5:edd529d4 r4:edd52980 [<c00681e0>] (handle_irq_event+0x0/0x6c) from [<c006b140>] (handle_level_irq+0xe8/0x100) r6:00000000 r5:edd529d4 r4:edd52980 r3:00022000 [<c006b058>] (handle_level_irq+0x0/0x100) from [<c00676f8>] (generic_handle_irq+0x30/0x40) r5:0000001f r4:0000001f [<c00676c8>] (generic_handle_irq+0x0/0x40) from [<c000f57c>] (handle_IRQ+0xd0/0x13c) r4:ea997b18 r3:000000e0 [<c000f4ac>] (handle_IRQ+0x0/0x13c) from [<c00086c4>] (armada_370_xp_handle_irq+0x4c/0x118) r8:000003ff r7:ea997b18 r6:ffffffff r5:60070013 r4:c0674dc0 [<c0008678>] (armada_370_xp_handle_irq+0x0/0x118) from [<c0013840>] (__irq_svc+0x40/0x70) Exception stack(0xea997b18 to 0xea997b60) 7b00: 00000001 20070013 7b20: 00000000 0000000b 20070013 eab27000 20070013 00000000 ed10103e eab27000 7b40: c06790d8 ea997b74 ea997b60 ea997b60 c04186c0 c04186c8 60070013 ffffffff r9:eab27000 r8:ed10103e r7:ea997b4c r6:ffffffff r5:60070013 r4:c04186c8 [<c04186a4>] (_raw_spin_unlock_irqrestore+0x0/0x54) from [<c0288fc0>] (uart_start+0x40/0x44) r4:c06790d8 r3:c028ddd8 [<c0288f80>] (uart_start+0x0/0x44) from [<c028982c>] (uart_write+0xe4/0xf4) r6:0000003e r5:00000000 r4:ed68ea90 r3:0000003e [<c0289748>] (uart_write+0x0/0xf4) from [<bf3a0d20>] (sl_xmit+0x1c4/0x228 [slip]) r10:ed388e60 r9:0000003c r8:ffffffdd r7:0000003e r6:ec02754c r5:ea717eb8 r4:ec027000 [<bf3a0b5c>] (sl_xmit+0x0/0x228 [slip]) from [<c0368d74>] (dev_hard_start_xmit+0x39c/0x6d0) r8:eaf163c0 r7:ec027000 r6:ea717eb8 r5:00000000 r4:00000000 Signed-off-by: Tyler Hall <tylerwhall@gmail.com> Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: Andre Naujoks <nautsch2@gmail.com> Cc: David S. Miller <davem@davemloft.net> Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-16 09:23:16 +07:00
spin_unlock_bh(&sl->lock);
flush_work(&sl->tx_work);
/* VSV = very important to remove timers */
#ifdef CONFIG_SLIP_SMART
del_timer_sync(&sl->keepalive_timer);
del_timer_sync(&sl->outfill_timer);
#endif
/* Flush network side */
unregister_netdev(sl->dev);
/* This will complete via sl_free_netdev */
}
static int slip_hangup(struct tty_struct *tty)
{
slip_close(tty);
return 0;
}
/************************************************************************
* STANDARD SLIP ENCAPSULATION *
************************************************************************/
static int slip_esc(unsigned char *s, unsigned char *d, int len)
{
unsigned char *ptr = d;
unsigned char c;
/*
* Send an initial END character to flush out any
* data that may have accumulated in the receiver
* due to line noise.
*/
*ptr++ = END;
/*
* For each byte in the packet, send the appropriate
* character sequence, according to the SLIP protocol.
*/
while (len-- > 0) {
switch (c = *s++) {
case END:
*ptr++ = ESC;
*ptr++ = ESC_END;
break;
case ESC:
*ptr++ = ESC;
*ptr++ = ESC_ESC;
break;
default:
*ptr++ = c;
break;
}
}
*ptr++ = END;
return ptr - d;
}
static void slip_unesc(struct slip *sl, unsigned char s)
{
switch (s) {
case END:
#ifdef CONFIG_SLIP_SMART
/* drop keeptest bit = VSV */
if (test_bit(SLF_KEEPTEST, &sl->flags))
clear_bit(SLF_KEEPTEST, &sl->flags);
#endif
if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
(sl->rcount > 2))
sl_bump(sl);
clear_bit(SLF_ESCAPE, &sl->flags);
sl->rcount = 0;
return;
case ESC:
set_bit(SLF_ESCAPE, &sl->flags);
return;
case ESC_ESC:
if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
s = ESC;
break;
case ESC_END:
if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
s = END;
break;
}
if (!test_bit(SLF_ERROR, &sl->flags)) {
if (sl->rcount < sl->buffsize) {
sl->rbuff[sl->rcount++] = s;
return;
}
sl->dev->stats.rx_over_errors++;
set_bit(SLF_ERROR, &sl->flags);
}
}
#ifdef CONFIG_SLIP_MODE_SLIP6
/************************************************************************
* 6 BIT SLIP ENCAPSULATION *
************************************************************************/
static int slip_esc6(unsigned char *s, unsigned char *d, int len)
{
unsigned char *ptr = d;
unsigned char c;
int i;
unsigned short v = 0;
short bits = 0;
/*
* Send an initial END character to flush out any
* data that may have accumulated in the receiver
* due to line noise.
*/
*ptr++ = 0x70;
/*
* Encode the packet into printable ascii characters
*/
for (i = 0; i < len; ++i) {
v = (v << 8) | s[i];
bits += 8;
while (bits >= 6) {
bits -= 6;
c = 0x30 + ((v >> bits) & 0x3F);
*ptr++ = c;
}
}
if (bits) {
c = 0x30 + ((v << (6 - bits)) & 0x3F);
*ptr++ = c;
}
*ptr++ = 0x70;
return ptr - d;
}
static void slip_unesc6(struct slip *sl, unsigned char s)
{
unsigned char c;
if (s == 0x70) {
#ifdef CONFIG_SLIP_SMART
/* drop keeptest bit = VSV */
if (test_bit(SLF_KEEPTEST, &sl->flags))
clear_bit(SLF_KEEPTEST, &sl->flags);
#endif
if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
(sl->rcount > 2))
sl_bump(sl);
sl->rcount = 0;
sl->xbits = 0;
sl->xdata = 0;
} else if (s >= 0x30 && s < 0x70) {
sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F);
sl->xbits += 6;
if (sl->xbits >= 8) {
sl->xbits -= 8;
c = (unsigned char)(sl->xdata >> sl->xbits);
if (!test_bit(SLF_ERROR, &sl->flags)) {
if (sl->rcount < sl->buffsize) {
sl->rbuff[sl->rcount++] = c;
return;
}
sl->dev->stats.rx_over_errors++;
set_bit(SLF_ERROR, &sl->flags);
}
}
}
}
#endif /* CONFIG_SLIP_MODE_SLIP6 */
/* Perform I/O control on an active SLIP channel. */
static int slip_ioctl(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg)
{
struct slip *sl = tty->disc_data;
unsigned int tmp;
int __user *p = (int __user *)arg;
/* First make sure we're connected. */
if (!sl || sl->magic != SLIP_MAGIC)
return -EINVAL;
switch (cmd) {
case SIOCGIFNAME:
tmp = strlen(sl->dev->name) + 1;
if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
return -EFAULT;
return 0;
case SIOCGIFENCAP:
if (put_user(sl->mode, p))
return -EFAULT;
return 0;
case SIOCSIFENCAP:
if (get_user(tmp, p))
return -EFAULT;
#ifndef SL_INCLUDE_CSLIP
if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE))
return -EINVAL;
#else
if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) ==
(SL_MODE_ADAPTIVE | SL_MODE_CSLIP))
/* return -EINVAL; */
tmp &= ~SL_MODE_ADAPTIVE;
#endif
#ifndef CONFIG_SLIP_MODE_SLIP6
if (tmp & SL_MODE_SLIP6)
return -EINVAL;
#endif
sl->mode = tmp;
sl->dev->type = ARPHRD_SLIP + sl->mode;
return 0;
case SIOCSIFHWADDR:
return -EINVAL;
#ifdef CONFIG_SLIP_SMART
/* VSV changes start here */
case SIOCSKEEPALIVE:
if (get_user(tmp, p))
return -EFAULT;
if (tmp > 255) /* max for unchar */
return -EINVAL;
spin_lock_bh(&sl->lock);
if (!sl->tty) {
spin_unlock_bh(&sl->lock);
return -ENODEV;
}
sl->keepalive = (u8)tmp;
if (sl->keepalive != 0) {
mod_timer(&sl->keepalive_timer,
jiffies + sl->keepalive * HZ);
set_bit(SLF_KEEPTEST, &sl->flags);
} else
del_timer(&sl->keepalive_timer);
spin_unlock_bh(&sl->lock);
return 0;
case SIOCGKEEPALIVE:
if (put_user(sl->keepalive, p))
return -EFAULT;
return 0;
case SIOCSOUTFILL:
if (get_user(tmp, p))
return -EFAULT;
if (tmp > 255) /* max for unchar */
return -EINVAL;
spin_lock_bh(&sl->lock);
if (!sl->tty) {
spin_unlock_bh(&sl->lock);
return -ENODEV;
}
sl->outfill = (u8)tmp;
if (sl->outfill != 0) {
mod_timer(&sl->outfill_timer,
jiffies + sl->outfill * HZ);
set_bit(SLF_OUTWAIT, &sl->flags);
} else
del_timer(&sl->outfill_timer);
spin_unlock_bh(&sl->lock);
return 0;
case SIOCGOUTFILL:
if (put_user(sl->outfill, p))
return -EFAULT;
return 0;
/* VSV changes end */
#endif
default:
return tty_mode_ioctl(tty, file, cmd, arg);
}
}
#ifdef CONFIG_COMPAT
static long slip_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:
case SIOCSKEEPALIVE:
case SIOCGKEEPALIVE:
case SIOCSOUTFILL:
case SIOCGOUTFILL:
return slip_ioctl(tty, file, cmd,
(unsigned long)compat_ptr(arg));
}
return -ENOIOCTLCMD;
}
#endif
/* VSV changes start here */
#ifdef CONFIG_SLIP_SMART
/* function do_ioctl called from net/core/dev.c
to allow get/set outfill/keepalive parameter
by ifconfig */
static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
{
struct slip *sl = netdev_priv(dev);
unsigned long *p = (unsigned long *)&rq->ifr_ifru;
if (sl == NULL) /* Allocation failed ?? */
return -ENODEV;
spin_lock_bh(&sl->lock);
if (!sl->tty) {
spin_unlock_bh(&sl->lock);
return -ENODEV;
}
switch (cmd) {
case SIOCSKEEPALIVE:
/* max for unchar */
if ((unsigned)*p > 255) {
spin_unlock_bh(&sl->lock);
return -EINVAL;
}
sl->keepalive = (u8)*p;
if (sl->keepalive != 0) {
sl->keepalive_timer.expires =
jiffies + sl->keepalive * HZ;
mod_timer(&sl->keepalive_timer,
jiffies + sl->keepalive * HZ);
set_bit(SLF_KEEPTEST, &sl->flags);
} else
del_timer(&sl->keepalive_timer);
break;
case SIOCGKEEPALIVE:
*p = sl->keepalive;
break;
case SIOCSOUTFILL:
if ((unsigned)*p > 255) { /* max for unchar */
spin_unlock_bh(&sl->lock);
return -EINVAL;
}
sl->outfill = (u8)*p;
if (sl->outfill != 0) {
mod_timer(&sl->outfill_timer,
jiffies + sl->outfill * HZ);
set_bit(SLF_OUTWAIT, &sl->flags);
} else
del_timer(&sl->outfill_timer);
break;
case SIOCGOUTFILL:
*p = sl->outfill;
break;
case SIOCSLEASE:
/* Resolve race condition, when ioctl'ing hanged up
and opened by another process device.
*/
if (sl->tty != current->signal->tty &&
sl->pid != current->pid) {
spin_unlock_bh(&sl->lock);
return -EPERM;
}
sl->leased = 0;
if (*p)
sl->leased = 1;
break;
case SIOCGLEASE:
*p = sl->leased;
}
spin_unlock_bh(&sl->lock);
return 0;
}
#endif
/* VSV changes end */
static struct tty_ldisc_ops sl_ldisc = {
.owner = THIS_MODULE,
.magic = TTY_LDISC_MAGIC,
.name = "slip",
.open = slip_open,
.close = slip_close,
.hangup = slip_hangup,
.ioctl = slip_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = slip_compat_ioctl,
#endif
.receive_buf = slip_receive_buf,
.write_wakeup = slip_write_wakeup,
};
static int __init slip_init(void)
{
int status;
if (slip_maxdev < 4)
slip_maxdev = 4; /* Sanity */
printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
#ifdef CONFIG_SLIP_MODE_SLIP6
" (6 bit encapsulation enabled)"
#endif
".\n",
SLIP_VERSION, slip_maxdev);
#if defined(SL_INCLUDE_CSLIP)
printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n");
#endif
#ifdef CONFIG_SLIP_SMART
printk(KERN_INFO "SLIP linefill/keepalive option.\n");
#endif
slip_devs = kzalloc(sizeof(struct net_device *)*slip_maxdev,
GFP_KERNEL);
if (!slip_devs)
return -ENOMEM;
/* Fill in our line protocol discipline, and register it */
status = tty_register_ldisc(N_SLIP, &sl_ldisc);
if (status != 0) {
printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
kfree(slip_devs);
}
return status;
}
static void __exit slip_exit(void)
{
int i;
struct net_device *dev;
struct slip *sl;
unsigned long timeout = jiffies + HZ;
int busy = 0;
if (slip_devs == NULL)
return;
/* First of all: check for active disciplines and hangup them.
*/
do {
if (busy)
msleep_interruptible(100);
busy = 0;
for (i = 0; i < slip_maxdev; i++) {
dev = slip_devs[i];
if (!dev)
continue;
sl = netdev_priv(dev);
spin_lock_bh(&sl->lock);
if (sl->tty) {
busy++;
tty_hangup(sl->tty);
}
spin_unlock_bh(&sl->lock);
}
} while (busy && time_before(jiffies, timeout));
/* FIXME: hangup is async so we should wait when doing this second
phase */
for (i = 0; i < slip_maxdev; i++) {
dev = slip_devs[i];
if (!dev)
continue;
slip_devs[i] = NULL;
sl = netdev_priv(dev);
if (sl->tty) {
printk(KERN_ERR "%s: tty discipline still running\n",
dev->name);
/* Intentionally leak the control block. */
dev->destructor = NULL;
}
unregister_netdev(dev);
}
kfree(slip_devs);
slip_devs = NULL;
i = tty_unregister_ldisc(N_SLIP);
if (i != 0)
printk(KERN_ERR "SLIP: can't unregister line discipline (err = %d)\n", i);
}
module_init(slip_init);
module_exit(slip_exit);
#ifdef CONFIG_SLIP_SMART
/*
* This is start of the code for multislip style line checking
* added by Stanislav Voronyi. All changes before marked VSV
*/
static void sl_outfill(unsigned long sls)
{
struct slip *sl = (struct slip *)sls;
spin_lock(&sl->lock);
if (sl->tty == NULL)
goto out;
if (sl->outfill) {
if (test_bit(SLF_OUTWAIT, &sl->flags)) {
/* no packets were transmitted, do outfill */
#ifdef CONFIG_SLIP_MODE_SLIP6
unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
#else
unsigned char s = END;
#endif
/* put END into tty queue. Is it right ??? */
if (!netif_queue_stopped(sl->dev)) {
/* if device busy no outfill */
sl->tty->ops->write(sl->tty, &s, 1);
}
} else
set_bit(SLF_OUTWAIT, &sl->flags);
mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
}
out:
spin_unlock(&sl->lock);
}
static void sl_keepalive(unsigned long sls)
{
struct slip *sl = (struct slip *)sls;
spin_lock(&sl->lock);
if (sl->tty == NULL)
goto out;
if (sl->keepalive) {
if (test_bit(SLF_KEEPTEST, &sl->flags)) {
/* keepalive still high :(, we must hangup */
if (sl->outfill)
/* outfill timer must be deleted too */
(void)del_timer(&sl->outfill_timer);
printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
/* this must hangup tty & close slip */
tty_hangup(sl->tty);
/* I think we need not something else */
goto out;
} else
set_bit(SLF_KEEPTEST, &sl->flags);
mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
}
out:
spin_unlock(&sl->lock);
}
#endif
MODULE_LICENSE("GPL");
MODULE_ALIAS_LDISC(N_SLIP);