linux/drivers/usb/serial/console.c

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/*
* USB Serial Console driver
*
* Copyright (C) 2001 - 2002 Greg Kroah-Hartman (greg@kroah.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* Thanks to Randy Dunlap for the original version of this code.
*
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/console.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
static int debug;
struct usbcons_info {
int magic;
int break_flag;
struct usb_serial_port *port;
};
static struct usbcons_info usbcons_info;
static struct console usbcons;
/*
* ------------------------------------------------------------
* USB Serial console driver
*
* Much of the code here is copied from drivers/char/serial.c
* and implements a phony serial console in the same way that
* serial.c does so that in case some software queries it,
* it will get the same results.
*
* Things that are different from the way the serial port code
* does things, is that we call the lower level usb-serial
* driver code to initialize the device, and we set the initial
* console speeds based on the command line arguments.
* ------------------------------------------------------------
*/
/*
* The parsing of the command line works exactly like the
* serial.c code, except that the specifier is "ttyUSB" instead
* of "ttyS".
*/
static int usb_console_setup(struct console *co, char *options)
{
struct usbcons_info *info = &usbcons_info;
int baud = 9600;
int bits = 8;
int parity = 'n';
int doflow = 0;
int cflag = CREAD | HUPCL | CLOCAL;
char *s;
struct usb_serial *serial;
struct usb_serial_port *port;
int retval = 0;
struct tty_struct *tty = NULL;
struct ktermios *termios = NULL, dummy;
dbg("%s", __func__);
if (options) {
baud = simple_strtoul(options, NULL, 10);
s = options;
while (*s >= '0' && *s <= '9')
s++;
if (*s)
parity = *s++;
if (*s)
bits = *s++ - '0';
if (*s)
doflow = (*s++ == 'r');
}
/* Sane default */
if (baud == 0)
baud = 9600;
switch (bits) {
case 7:
cflag |= CS7;
break;
default:
case 8:
cflag |= CS8;
break;
}
switch (parity) {
case 'o': case 'O':
cflag |= PARODD;
break;
case 'e': case 'E':
cflag |= PARENB;
break;
}
co->cflag = cflag;
/*
* no need to check the index here: if the index is wrong, console
* code won't call us
*/
serial = usb_serial_get_by_index(co->index);
if (serial == NULL) {
/* no device is connected yet, sorry :( */
err("No USB device connected to ttyUSB%i", co->index);
return -ENODEV;
}
port = serial->port[0];
port->port.tty = NULL;
info->port = port;
++port->port.count;
if (port->port.count == 1) {
if (serial->type->set_termios) {
/*
* allocate a fake tty so the driver can initialize
* the termios structure, then later call set_termios to
* configure according to command line arguments
*/
tty = kzalloc(sizeof(*tty), GFP_KERNEL);
if (!tty) {
retval = -ENOMEM;
err("no more memory");
goto reset_open_count;
}
termios = kzalloc(sizeof(*termios), GFP_KERNEL);
if (!termios) {
retval = -ENOMEM;
err("no more memory");
goto free_tty;
}
memset(&dummy, 0, sizeof(struct ktermios));
tty->termios = termios;
port->port.tty = tty;
}
/* only call the device specific open if this
* is the first time the port is opened */
if (serial->type->open)
retval = serial->type->open(NULL, port, NULL);
else
retval = usb_serial_generic_open(NULL, port, NULL);
if (retval) {
err("could not open USB console port");
goto free_termios;
}
if (serial->type->set_termios) {
termios->c_cflag = cflag;
tty_termios_encode_baud_rate(termios, baud, baud);
serial->type->set_termios(NULL, port, &dummy);
port->port.tty = NULL;
kfree(termios);
kfree(tty);
}
}
USB: usb_serial: clean tty reference in the last close When a usb serial adapter is used as console, the usb serial console driver bumps the open_count on the port struct used but doesn't attach a real tty to it (only a fake one temporaly). If this port is opened later using the regular character device interface, the open method won't initialize the port, which is the expected, and will receive a brand new tty struct created by tty layer, which will be stored in port->tty. When the last close is issued, open_count won't be 0 because of the console usage and the port->tty will still contain the old tty value. This is the last ttyUSB<n> close so the allocated tty will be freed by the tty layer. The usb_serial and usb_serial_port are still in use by the console, so port_free() won't be called (serial_close() -> usb_serial_put() -> destroy_serial() -> port_free()), so the scheduled work (port->work, usb_serial_port_work()) will still run. And usb_serial_port_work() does: (...) tty = port->tty; if (!tty) return; tty_wakeup(tty); which causes (manually copied): Faulting instruction address: 0x6b6b6b68 Oops: Kernel access of bad area, sig: 11 [#1] PREEMPT PowerMac Modules linked in: binfmt_misc ipv6 nfs lockd nfs_acl sunrpc dm_snapshot dm_mirror dm_mod hfsplus uinput ams input_polldev genrtc cpufreq_powersave i2c_powermac therm_adt746x snd_aoa_codec_tas snd_aoa_fabric_layout snd_aoa joydev snd_aoa_i2sbus snd_pcm_oss snd_mixer_oss snd_pcm snd_timer snd_page_alloc pmac_zilog serial_core evdev ide_cd cdrom snd appletouch soundcore snd_aoa_soundbus bcm43xx firmware_class usbhid ieee80211softmac ff_memless firewire_ohci firewire_core ieee80211 ieee80211_crypt crc_itu_t sungem sungem_phy uninorth_agp agpart ssb NIP: 6b6b6b68 LR: c01b2108 CTR: 6b6b6b6b REGS: c106de80 TRAP: 0400 Not tainted (2.6.24-rc2) MSR: 40009032 <EE,ME,IR,DR> CR: 82004024 XER: 00000000 TASK = c106b4c0[5] 'events/0' THREAD: c106c000 GPR00: 6b6b6b6b c106df30 c106b4c0 c2d613a0 00009032 00000001 00001a00 00000001 GPR08: 00000008 00000000 00000000 c106c000 42004028 00000000 016ffbe0 0171a724 GPR16: 016ffcf4 00240e24 00240e70 016fee68 016ff9a4 c03046c4 c0327f50 c03046fc GPR24: c106b6b9 c106b4c0 c101d610 c106c000 c02160fc c1eac1dc c2d613ac c2d613a0 NIP [6b6b6b68] 0x6b6b6b68 LR [c01b2108] tty_wakeup+0x6c/0x9c Call Trace: [c106df30] [c01b20e8] tty_wakeup+0x4c/0x9c (unreliable) [c106df40] [c0216138] usb_serial_port_work+0x3c/0x78 [c106df50] [c00432e8] run_workqueue+0xc4/0x15c [c106df90] [c0043798] worker_thread+0xa0/0x124 [c106dfd0] [c0048224] kthread+0x48/0x84 [c106dff0] [c00129bc] kernel_thread+0x44/0x60 Instruction dump: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX Slab corruption: size-2048 start=c2d613a0, len=2048 Redzone: 0x9f911029d74e35b/0x9f911029d74e35b. Last user: [<c01b16d8>](release_one_tty+0xbc/0xf4) 050: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b Prev obj: start=c2d60b88, len=2048 Redzone: 0x9f911029d74e35b/0x9f911029d74e35b. Last user: [<c00f30ec>](show_stat+0x410/0x428) 000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b This patch avoids this, clearing port->tty considering if the port is used as serial console or not Signed-off-by: Aristeu Rozanski <arozansk@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-11-12 20:15:02 +00:00
port->console = 1;
retval = 0;
out:
return retval;
free_termios:
kfree(termios);
port->port.tty = NULL;
free_tty:
kfree(tty);
reset_open_count:
port->port.count = 0;
goto out;
}
static void usb_console_write(struct console *co,
const char *buf, unsigned count)
{
static struct usbcons_info *info = &usbcons_info;
struct usb_serial_port *port = info->port;
struct usb_serial *serial;
int retval = -ENODEV;
if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED)
return;
serial = port->serial;
if (count == 0)
return;
dbg("%s - port %d, %d byte(s)", __func__, port->number, count);
if (!port->port.count) {
dbg("%s - port not opened", __func__);
return;
}
while (count) {
unsigned int i;
unsigned int lf;
/* search for LF so we can insert CR if necessary */
for (i = 0, lf = 0 ; i < count ; i++) {
if (*(buf + i) == 10) {
lf = 1;
i++;
break;
}
}
/* pass on to the driver specific version of this function if
it is available */
if (serial->type->write)
retval = serial->type->write(NULL, port, buf, i);
else
retval = usb_serial_generic_write(NULL, port, buf, i);
dbg("%s - return value : %d", __func__, retval);
if (lf) {
/* append CR after LF */
unsigned char cr = 13;
if (serial->type->write)
retval = serial->type->write(NULL,
port, &cr, 1);
else
retval = usb_serial_generic_write(NULL,
port, &cr, 1);
dbg("%s - return value : %d", __func__, retval);
}
buf += i;
count -= i;
}
}
static struct console usbcons = {
.name = "ttyUSB",
.write = usb_console_write,
.setup = usb_console_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
};
void usb_serial_console_disconnect(struct usb_serial *serial)
{
if (serial && serial->port && serial->port[0]
&& serial->port[0] == usbcons_info.port) {
usb_serial_console_exit();
usb_serial_put(serial);
}
}
void usb_serial_console_init(int serial_debug, int minor)
{
debug = serial_debug;
if (minor == 0) {
/*
* Call register_console() if this is the first device plugged
* in. If we call it earlier, then the callback to
* console_setup() will fail, as there is not a device seen by
* the USB subsystem yet.
*/
/*
* Register console.
* NOTES:
* console_setup() is called (back) immediately (from
* register_console). console_write() is called immediately
* from register_console iff CON_PRINTBUFFER is set in flags.
*/
dbg("registering the USB serial console.");
register_console(&usbcons);
}
}
void usb_serial_console_exit(void)
{
if (usbcons_info.port) {
unregister_console(&usbcons);
if (usbcons_info.port->port.count)
usbcons_info.port->port.count--;
usbcons_info.port = NULL;
}
}