static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
unsigned char __user *buf, size_t nr)
{
unsigned char __user *b = buf;
DECLARE_WAITQUEUE(wait, current);
int c;
int minimum, time;
ssize_t retval = 0;
ssize_t size;
long timeout;
unsigned long flags;
int packet;
do_it_again:
BUG_ON(!tty->read_buf);
c = job_control(tty, file);
if (c < 0)
return c;
minimum = time = 0;
timeout = MAX_SCHEDULE_TIMEOUT;
if (!tty->icanon) {
time = (HZ / 10) * TIME_CHAR(tty);
minimum = MIN_CHAR(tty);
if (minimum) {
if (time)
tty->minimum_to_wake = 1;
else if (!waitqueue_active(&tty->read_wait) ||
(tty->minimum_to_wake > minimum))
tty->minimum_to_wake = minimum;
} else {
timeout = 0;
if (time) {
timeout = time;
time = 0;
}
tty->minimum_to_wake = minimum = 1;
}
}
if (file->f_flags & O_NONBLOCK) {
if (!mutex_trylock(&tty->atomic_read_lock))
return -EAGAIN;
} else {
if (mutex_lock_interruptible(&tty->atomic_read_lock))
return -ERESTARTSYS;
}
packet = tty->packet;
add_wait_queue(&tty->read_wait, &wait);
while (nr) {
if (packet && tty->link->ctrl_status) {
unsigned char cs;
if (b != buf)
break;
spin_lock_irqsave(&tty->link->ctrl_lock, flags);
cs = tty->link->ctrl_status;
tty->link->ctrl_status = 0;
spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
if (tty_put_user(tty, cs, b++)) {
retval = -EFAULT;
b--;
break;
}
nr--;
break;
}
set_current_state(TASK_INTERRUPTIBLE);
if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
((minimum - (b - buf)) >= 1))
tty->minimum_to_wake = (minimum - (b - buf));
if (!input_available_p(tty, 0)) {
if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
retval = -EIO;
break;
}
if (tty_hung_up_p(file))
break;
if (!timeout)
break;
if (file->f_flags & O_NONBLOCK) {
retval = -EAGAIN;
break;
}
if (signal_pending(current)) {
retval = -ERESTARTSYS;
break;
}
n_tty_set_room(tty);
timeout = schedule_timeout(timeout);
BUG_ON(!tty->read_buf);
continue;
}
__set_current_state(TASK_RUNNING);
if (packet && b == buf) {
if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
retval = -EFAULT;
b--;
break;
}
nr--;
}
if (tty->icanon && !L_EXTPROC(tty)) {
while (nr && tty->read_cnt) {
int eol;
eol = test_and_clear_bit(tty->read_tail,
tty->read_flags);
c = tty->read_buf[tty->read_tail];
spin_lock_irqsave(&tty->read_lock, flags);
tty->read_tail = ((tty->read_tail+1) &
(N_TTY_BUF_SIZE-1));
tty->read_cnt--;
if (eol) {
if (--tty->canon_data < 0)
tty->canon_data = 0;
}
spin_unlock_irqrestore(&tty->read_lock, flags);
if (!eol || (c != __DISABLED_CHAR)) {
if (tty_put_user(tty, c, b++)) {
retval = -EFAULT;
b--;
break;
}
nr--;
}
if (eol) {
tty_audit_push(tty);
break;
}
}
if (retval)
break;
} else {
int uncopied;
uncopied = copy_from_read_buf(tty, &b, &nr);
uncopied += copy_from_read_buf(tty, &b, &nr);
if (uncopied) {
retval = -EFAULT;
break;
}
}
if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
n_tty_set_room(tty);
check_unthrottle(tty);
}
if (b - buf >= minimum)
break;
if (time)
timeout = time;
}
mutex_unlock(&tty->atomic_read_lock);
remove_wait_queue(&tty->read_wait, &wait);
if (!waitqueue_active(&tty->read_wait))
tty->minimum_to_wake = minimum;
__set_current_state(TASK_RUNNING);
size = b - buf;
if (size) {
retval = size;
if (nr)
clear_bit(TTY_PUSH, &tty->flags);
} else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
goto do_it_again;
n_tty_set_room(tty);
return retval;
}
static ssize_t read_chan(struct tty_struct *tty, struct file *file,
unsigned char __user *buf, size_t nr)
{
unsigned char __user *b = buf;
DECLARE_WAITQUEUE(wait, current);
int c;
int minimum, time;
ssize_t retval = 0;
ssize_t size;
long timeout;
unsigned long flags;
do_it_again:
if (!tty->read_buf) {
printk("n_tty_read_chan: called with read_buf == NULL?!?\n");
return -EIO;
}
c = job_control(tty, file);
if(c < 0)
return c;
minimum = time = 0;
timeout = MAX_SCHEDULE_TIMEOUT;
if (!tty->icanon) {
time = (HZ / 10) * TIME_CHAR(tty);
minimum = MIN_CHAR(tty);
if (minimum) {
if (time)
tty->minimum_to_wake = 1;
else if (!waitqueue_active(&tty->read_wait) ||
(tty->minimum_to_wake > minimum))
tty->minimum_to_wake = minimum;
} else {
timeout = 0;
if (time) {
timeout = time;
time = 0;
}
tty->minimum_to_wake = minimum = 1;
}
}
/*
* Internal serialization of reads.
*/
if (tx_cache_get_file_ro(file)->f_flags & O_NONBLOCK) {
if (!mutex_trylock(&tty->atomic_read_lock))
return -EAGAIN;
}
else {
if (mutex_lock_interruptible(&tty->atomic_read_lock))
return -ERESTARTSYS;
}
add_wait_queue(&tty->read_wait, &wait);
while (nr) {
/* First test for status change. */
if (tty->packet && tty->link->ctrl_status) {
unsigned char cs;
if (b != buf)
break;
cs = tty->link->ctrl_status;
tty->link->ctrl_status = 0;
if (put_user(cs, b++)) {
retval = -EFAULT;
b--;
break;
}
nr--;
break;
}
/* This statement must be first before checking for input
so that any interrupt will set the state back to
TASK_RUNNING. */
set_current_state(TASK_INTERRUPTIBLE);
if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
((minimum - (b - buf)) >= 1))
tty->minimum_to_wake = (minimum - (b - buf));
if (!input_available_p(tty, 0)) {
if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
retval = -EIO;
break;
}
if (tty_hung_up_p(file))
break;
if (!timeout)
break;
if (tx_cache_get_file_ro(file)->f_flags & O_NONBLOCK) {
retval = -EAGAIN;
break;
}
if (signal_pending(current)) {
retval = -ERESTARTSYS;
break;
}
n_tty_set_room(tty);
timeout = schedule_timeout(timeout);
continue;
}
__set_current_state(TASK_RUNNING);
/* Deal with packet mode. */
if (tty->packet && b == buf) {
if (put_user(TIOCPKT_DATA, b++)) {
retval = -EFAULT;
b--;
break;
}
nr--;
}
if (tty->icanon) {
/* N.B. avoid overrun if nr == 0 */
while (nr && tty->read_cnt) {
int eol;
eol = test_and_clear_bit(tty->read_tail,
tty->read_flags);
c = tty->read_buf[tty->read_tail];
spin_lock_irqsave(&tty->read_lock, flags);
tty->read_tail = ((tty->read_tail+1) &
(N_TTY_BUF_SIZE-1));
tty->read_cnt--;
if (eol) {
/* this test should be redundant:
* we shouldn't be reading data if
* canon_data is 0
*/
if (--tty->canon_data < 0)
tty->canon_data = 0;
}
spin_unlock_irqrestore(&tty->read_lock, flags);
if (!eol || (c != __DISABLED_CHAR)) {
if (put_user(c, b++)) {
retval = -EFAULT;
b--;
break;
}
nr--;
}
if (eol)
break;
}
if (retval)
break;
} else {
int uncopied;
uncopied = copy_from_read_buf(tty, &b, &nr);
uncopied += copy_from_read_buf(tty, &b, &nr);
if (uncopied) {
retval = -EFAULT;
break;
}
}
/* If there is enough space in the read buffer now, let the
* low-level driver know. We use n_tty_chars_in_buffer() to
* check the buffer, as it now knows about canonical mode.
* Otherwise, if the driver is throttled and the line is
* longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
* we won't get any more characters.
*/
if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
n_tty_set_room(tty);
check_unthrottle(tty);
}
if (b - buf >= minimum)
break;
if (time)
timeout = time;
}
mutex_unlock(&tty->atomic_read_lock);
remove_wait_queue(&tty->read_wait, &wait);
if (!waitqueue_active(&tty->read_wait))
tty->minimum_to_wake = minimum;
__set_current_state(TASK_RUNNING);
size = b - buf;
if (size) {
retval = size;
if (nr)
clear_bit(TTY_PUSH, &tty->flags);
} else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
goto do_it_again;
n_tty_set_room(tty);
return retval;
}
