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kernel_optimize_test/drivers/char/tty_ioctl.c
Alan Cox af9b897ee6 [PATCH] tty layer comment the locking assumptions and functions somewhat 
Doesn't fix them but does show up some interesting areas that need review
and fixing.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-08-27 11:01:34 -07:00

607 lines
15 KiB
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/*
* linux/drivers/char/tty_ioctl.c
*
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
*
* Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
* which can be dynamically activated and de-activated by the line
* discipline handling modules (like SLIP).
*/
#include <linux/types.h>
#include <linux/termios.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/tty.h>
#include <linux/fcntl.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/bitops.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#undef TTY_DEBUG_WAIT_UNTIL_SENT
#undef DEBUG
/*
* Internal flag options for termios setting behavior
*/
#define TERMIOS_FLUSH 1
#define TERMIOS_WAIT 2
#define TERMIOS_TERMIO 4
/**
* tty_wait_until_sent - wait for I/O to finish
* @tty: tty we are waiting for
* @timeout: how long we will wait
*
* Wait for characters pending in a tty driver to hit the wire, or
* for a timeout to occur (eg due to flow control)
*
* Locking: none
*/
void tty_wait_until_sent(struct tty_struct * tty, long timeout)
{
DECLARE_WAITQUEUE(wait, current);
#ifdef TTY_DEBUG_WAIT_UNTIL_SENT
char buf[64];
printk(KERN_DEBUG "%s wait until sent...\n", tty_name(tty, buf));
#endif
if (!tty->driver->chars_in_buffer)
return;
add_wait_queue(&tty->write_wait, &wait);
if (!timeout)
timeout = MAX_SCHEDULE_TIMEOUT;
do {
#ifdef TTY_DEBUG_WAIT_UNTIL_SENT
printk(KERN_DEBUG "waiting %s...(%d)\n", tty_name(tty, buf),
tty->driver->chars_in_buffer(tty));
#endif
set_current_state(TASK_INTERRUPTIBLE);
if (signal_pending(current))
goto stop_waiting;
if (!tty->driver->chars_in_buffer(tty))
break;
timeout = schedule_timeout(timeout);
} while (timeout);
if (tty->driver->wait_until_sent)
tty->driver->wait_until_sent(tty, timeout);
stop_waiting:
set_current_state(TASK_RUNNING);
remove_wait_queue(&tty->write_wait, &wait);
}
EXPORT_SYMBOL(tty_wait_until_sent);
static void unset_locked_termios(struct termios *termios,
struct termios *old,
struct termios *locked)
{
int i;
#define NOSET_MASK(x,y,z) (x = ((x) & ~(z)) | ((y) & (z)))
if (!locked) {
printk(KERN_WARNING "Warning?!? termios_locked is NULL.\n");
return;
}
NOSET_MASK(termios->c_iflag, old->c_iflag, locked->c_iflag);
NOSET_MASK(termios->c_oflag, old->c_oflag, locked->c_oflag);
NOSET_MASK(termios->c_cflag, old->c_cflag, locked->c_cflag);
NOSET_MASK(termios->c_lflag, old->c_lflag, locked->c_lflag);
termios->c_line = locked->c_line ? old->c_line : termios->c_line;
for (i=0; i < NCCS; i++)
termios->c_cc[i] = locked->c_cc[i] ?
old->c_cc[i] : termios->c_cc[i];
}
/**
* change_termios - update termios values
* @tty: tty to update
* @new_termios: desired new value
*
* Perform updates to the termios values set on this terminal. There
* is a bit of layering violation here with n_tty in terms of the
* internal knowledge of this function.
*
* Locking: termios_sem
*/
static void change_termios(struct tty_struct * tty, struct termios * new_termios)
{
int canon_change;
struct termios old_termios = *tty->termios;
struct tty_ldisc *ld;
/*
* Perform the actual termios internal changes under lock.
*/
/* FIXME: we need to decide on some locking/ordering semantics
for the set_termios notification eventually */
down(&tty->termios_sem);
*tty->termios = *new_termios;
unset_locked_termios(tty->termios, &old_termios, tty->termios_locked);
canon_change = (old_termios.c_lflag ^ tty->termios->c_lflag) & ICANON;
if (canon_change) {
memset(&tty->read_flags, 0, sizeof tty->read_flags);
tty->canon_head = tty->read_tail;
tty->canon_data = 0;
tty->erasing = 0;
}
if (canon_change && !L_ICANON(tty) && tty->read_cnt)
/* Get characters left over from canonical mode. */
wake_up_interruptible(&tty->read_wait);
/* See if packet mode change of state. */
if (tty->link && tty->link->packet) {
int old_flow = ((old_termios.c_iflag & IXON) &&
(old_termios.c_cc[VSTOP] == '\023') &&
(old_termios.c_cc[VSTART] == '\021'));
int new_flow = (I_IXON(tty) &&
STOP_CHAR(tty) == '\023' &&
START_CHAR(tty) == '\021');
if (old_flow != new_flow) {
tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP);
if (new_flow)
tty->ctrl_status |= TIOCPKT_DOSTOP;
else
tty->ctrl_status |= TIOCPKT_NOSTOP;
wake_up_interruptible(&tty->link->read_wait);
}
}
if (tty->driver->set_termios)
(*tty->driver->set_termios)(tty, &old_termios);
ld = tty_ldisc_ref(tty);
if (ld != NULL) {
if (ld->set_termios)
(ld->set_termios)(tty, &old_termios);
tty_ldisc_deref(ld);
}
up(&tty->termios_sem);
}
/**
* set_termios - set termios values for a tty
* @tty: terminal device
* @arg: user data
* @opt: option information
*
* Helper function to prepare termios data and run neccessary other
* functions before using change_termios to do the actual changes.
*
* Locking:
* Called functions take ldisc and termios_sem locks
*/
static int set_termios(struct tty_struct * tty, void __user *arg, int opt)
{
struct termios tmp_termios;
struct tty_ldisc *ld;
int retval = tty_check_change(tty);
if (retval)
return retval;
if (opt & TERMIOS_TERMIO) {
memcpy(&tmp_termios, tty->termios, sizeof(struct termios));
if (user_termio_to_kernel_termios(&tmp_termios,
(struct termio __user *)arg))
return -EFAULT;
} else {
if (user_termios_to_kernel_termios(&tmp_termios,
(struct termios __user *)arg))
return -EFAULT;
}
ld = tty_ldisc_ref(tty);
if (ld != NULL) {
if ((opt & TERMIOS_FLUSH) && ld->flush_buffer)
ld->flush_buffer(tty);
tty_ldisc_deref(ld);
}
if (opt & TERMIOS_WAIT) {
tty_wait_until_sent(tty, 0);
if (signal_pending(current))
return -EINTR;
}
change_termios(tty, &tmp_termios);
return 0;
}
static int get_termio(struct tty_struct * tty, struct termio __user * termio)
{
if (kernel_termios_to_user_termio(termio, tty->termios))
return -EFAULT;
return 0;
}
static unsigned long inq_canon(struct tty_struct * tty)
{
int nr, head, tail;
if (!tty->canon_data || !tty->read_buf)
return 0;
head = tty->canon_head;
tail = tty->read_tail;
nr = (head - tail) & (N_TTY_BUF_SIZE-1);
/* Skip EOF-chars.. */
while (head != tail) {
if (test_bit(tail, tty->read_flags) &&
tty->read_buf[tail] == __DISABLED_CHAR)
nr--;
tail = (tail+1) & (N_TTY_BUF_SIZE-1);
}
return nr;
}
#ifdef TIOCGETP
/*
* These are deprecated, but there is limited support..
*
* The "sg_flags" translation is a joke..
*/
static int get_sgflags(struct tty_struct * tty)
{
int flags = 0;
if (!(tty->termios->c_lflag & ICANON)) {
if (tty->termios->c_lflag & ISIG)
flags |= 0x02; /* cbreak */
else
flags |= 0x20; /* raw */
}
if (tty->termios->c_lflag & ECHO)
flags |= 0x08; /* echo */
if (tty->termios->c_oflag & OPOST)
if (tty->termios->c_oflag & ONLCR)
flags |= 0x10; /* crmod */
return flags;
}
static int get_sgttyb(struct tty_struct * tty, struct sgttyb __user * sgttyb)
{
struct sgttyb tmp;
down(&tty->termios_sem);
tmp.sg_ispeed = 0;
tmp.sg_ospeed = 0;
tmp.sg_erase = tty->termios->c_cc[VERASE];
tmp.sg_kill = tty->termios->c_cc[VKILL];
tmp.sg_flags = get_sgflags(tty);
up(&tty->termios_sem);
return copy_to_user(sgttyb, &tmp, sizeof(tmp)) ? -EFAULT : 0;
}
static void set_sgflags(struct termios * termios, int flags)
{
termios->c_iflag = ICRNL | IXON;
termios->c_oflag = 0;
termios->c_lflag = ISIG | ICANON;
if (flags & 0x02) { /* cbreak */
termios->c_iflag = 0;
termios->c_lflag &= ~ICANON;
}
if (flags & 0x08) { /* echo */
termios->c_lflag |= ECHO | ECHOE | ECHOK |
ECHOCTL | ECHOKE | IEXTEN;
}
if (flags & 0x10) { /* crmod */
termios->c_oflag |= OPOST | ONLCR;
}
if (flags & 0x20) { /* raw */
termios->c_iflag = 0;
termios->c_lflag &= ~(ISIG | ICANON);
}
if (!(termios->c_lflag & ICANON)) {
termios->c_cc[VMIN] = 1;
termios->c_cc[VTIME] = 0;
}
}
/**
* set_sgttyb - set legacy terminal values
* @tty: tty structure
* @sgttyb: pointer to old style terminal structure
*
* Updates a terminal from the legacy BSD style terminal information
* structure.
*
* Locking: termios_sem
*/
static int set_sgttyb(struct tty_struct * tty, struct sgttyb __user * sgttyb)
{
int retval;
struct sgttyb tmp;
struct termios termios;
retval = tty_check_change(tty);
if (retval)
return retval;
if (copy_from_user(&tmp, sgttyb, sizeof(tmp)))
return -EFAULT;
down(&tty->termios_sem);
termios = *tty->termios;
termios.c_cc[VERASE] = tmp.sg_erase;
termios.c_cc[VKILL] = tmp.sg_kill;
set_sgflags(&termios, tmp.sg_flags);
up(&tty->termios_sem);
change_termios(tty, &termios);
return 0;
}
#endif
#ifdef TIOCGETC
static int get_tchars(struct tty_struct * tty, struct tchars __user * tchars)
{
struct tchars tmp;
tmp.t_intrc = tty->termios->c_cc[VINTR];
tmp.t_quitc = tty->termios->c_cc[VQUIT];
tmp.t_startc = tty->termios->c_cc[VSTART];
tmp.t_stopc = tty->termios->c_cc[VSTOP];
tmp.t_eofc = tty->termios->c_cc[VEOF];
tmp.t_brkc = tty->termios->c_cc[VEOL2]; /* what is brkc anyway? */
return copy_to_user(tchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
}
static int set_tchars(struct tty_struct * tty, struct tchars __user * tchars)
{
struct tchars tmp;
if (copy_from_user(&tmp, tchars, sizeof(tmp)))
return -EFAULT;
tty->termios->c_cc[VINTR] = tmp.t_intrc;
tty->termios->c_cc[VQUIT] = tmp.t_quitc;
tty->termios->c_cc[VSTART] = tmp.t_startc;
tty->termios->c_cc[VSTOP] = tmp.t_stopc;
tty->termios->c_cc[VEOF] = tmp.t_eofc;
tty->termios->c_cc[VEOL2] = tmp.t_brkc; /* what is brkc anyway? */
return 0;
}
#endif
#ifdef TIOCGLTC
static int get_ltchars(struct tty_struct * tty, struct ltchars __user * ltchars)
{
struct ltchars tmp;
tmp.t_suspc = tty->termios->c_cc[VSUSP];
tmp.t_dsuspc = tty->termios->c_cc[VSUSP]; /* what is dsuspc anyway? */
tmp.t_rprntc = tty->termios->c_cc[VREPRINT];
tmp.t_flushc = tty->termios->c_cc[VEOL2]; /* what is flushc anyway? */
tmp.t_werasc = tty->termios->c_cc[VWERASE];
tmp.t_lnextc = tty->termios->c_cc[VLNEXT];
return copy_to_user(ltchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
}
static int set_ltchars(struct tty_struct * tty, struct ltchars __user * ltchars)
{
struct ltchars tmp;
if (copy_from_user(&tmp, ltchars, sizeof(tmp)))
return -EFAULT;
tty->termios->c_cc[VSUSP] = tmp.t_suspc;
tty->termios->c_cc[VEOL2] = tmp.t_dsuspc; /* what is dsuspc anyway? */
tty->termios->c_cc[VREPRINT] = tmp.t_rprntc;
tty->termios->c_cc[VEOL2] = tmp.t_flushc; /* what is flushc anyway? */
tty->termios->c_cc[VWERASE] = tmp.t_werasc;
tty->termios->c_cc[VLNEXT] = tmp.t_lnextc;
return 0;
}
#endif
/**
* send_prio_char - send priority character
*
* Send a high priority character to the tty even if stopped
*
* Locking: none
*
* FIXME: overlapping calls with start/stop tty lose state of tty
*/
static void send_prio_char(struct tty_struct *tty, char ch)
{
int was_stopped = tty->stopped;
if (tty->driver->send_xchar) {
tty->driver->send_xchar(tty, ch);
return;
}
if (was_stopped)
start_tty(tty);
tty->driver->write(tty, &ch, 1);
if (was_stopped)
stop_tty(tty);
}
int n_tty_ioctl(struct tty_struct * tty, struct file * file,
unsigned int cmd, unsigned long arg)
{
struct tty_struct * real_tty;
void __user *p = (void __user *)arg;
int retval;
struct tty_ldisc *ld;
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
real_tty = tty->link;
else
real_tty = tty;
switch (cmd) {
#ifdef TIOCGETP
case TIOCGETP:
return get_sgttyb(real_tty, (struct sgttyb __user *) arg);
case TIOCSETP:
case TIOCSETN:
return set_sgttyb(real_tty, (struct sgttyb __user *) arg);
#endif
#ifdef TIOCGETC
case TIOCGETC:
return get_tchars(real_tty, p);
case TIOCSETC:
return set_tchars(real_tty, p);
#endif
#ifdef TIOCGLTC
case TIOCGLTC:
return get_ltchars(real_tty, p);
case TIOCSLTC:
return set_ltchars(real_tty, p);
#endif
case TCGETS:
if (kernel_termios_to_user_termios((struct termios __user *)arg, real_tty->termios))
return -EFAULT;
return 0;
case TCSETSF:
return set_termios(real_tty, p, TERMIOS_FLUSH | TERMIOS_WAIT);
case TCSETSW:
return set_termios(real_tty, p, TERMIOS_WAIT);
case TCSETS:
return set_termios(real_tty, p, 0);
case TCGETA:
return get_termio(real_tty, p);
case TCSETAF:
return set_termios(real_tty, p, TERMIOS_FLUSH | TERMIOS_WAIT | TERMIOS_TERMIO);
case TCSETAW:
return set_termios(real_tty, p, TERMIOS_WAIT | TERMIOS_TERMIO);
case TCSETA:
return set_termios(real_tty, p, TERMIOS_TERMIO);
case TCXONC:
retval = tty_check_change(tty);
if (retval)
return retval;
switch (arg) {
case TCOOFF:
if (!tty->flow_stopped) {
tty->flow_stopped = 1;
stop_tty(tty);
}
break;
case TCOON:
if (tty->flow_stopped) {
tty->flow_stopped = 0;
start_tty(tty);
}
break;
case TCIOFF:
if (STOP_CHAR(tty) != __DISABLED_CHAR)
send_prio_char(tty, STOP_CHAR(tty));
break;
case TCION:
if (START_CHAR(tty) != __DISABLED_CHAR)
send_prio_char(tty, START_CHAR(tty));
break;
default:
return -EINVAL;
}
return 0;
case TCFLSH:
retval = tty_check_change(tty);
if (retval)
return retval;
ld = tty_ldisc_ref(tty);
switch (arg) {
case TCIFLUSH:
if (ld && ld->flush_buffer)
ld->flush_buffer(tty);
break;
case TCIOFLUSH:
if (ld && ld->flush_buffer)
ld->flush_buffer(tty);
/* fall through */
case TCOFLUSH:
if (tty->driver->flush_buffer)
tty->driver->flush_buffer(tty);
break;
default:
tty_ldisc_deref(ld);
return -EINVAL;
}
tty_ldisc_deref(ld);
return 0;
case TIOCOUTQ:
return put_user(tty->driver->chars_in_buffer ?
tty->driver->chars_in_buffer(tty) : 0,
(int __user *) arg);
case TIOCINQ:
retval = tty->read_cnt;
if (L_ICANON(tty))
retval = inq_canon(tty);
return put_user(retval, (unsigned int __user *) arg);
case TIOCGLCKTRMIOS:
if (kernel_termios_to_user_termios((struct termios __user *)arg, real_tty->termios_locked))
return -EFAULT;
return 0;
case TIOCSLCKTRMIOS:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (user_termios_to_kernel_termios(real_tty->termios_locked, (struct termios __user *) arg))
return -EFAULT;
return 0;
case TIOCPKT:
{
int pktmode;
if (tty->driver->type != TTY_DRIVER_TYPE_PTY ||
tty->driver->subtype != PTY_TYPE_MASTER)
return -ENOTTY;
if (get_user(pktmode, (int __user *) arg))
return -EFAULT;
if (pktmode) {
if (!tty->packet) {
tty->packet = 1;
tty->link->ctrl_status = 0;
}
} else
tty->packet = 0;
return 0;
}
case TIOCGSOFTCAR:
return put_user(C_CLOCAL(tty) ? 1 : 0, (int __user *)arg);
case TIOCSSOFTCAR:
if (get_user(arg, (unsigned int __user *) arg))
return -EFAULT;
down(&tty->termios_sem);
tty->termios->c_cflag =
((tty->termios->c_cflag & ~CLOCAL) |
(arg ? CLOCAL : 0));
up(&tty->termios_sem);
return 0;
default:
return -ENOIOCTLCMD;
}
}
EXPORT_SYMBOL(n_tty_ioctl);
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