n_tty: Encapsulate minimum_to_wake within N_TTY
minimum_to_wake is unique to N_TTY processing, and belongs in
per-ldisc data.
Add the ldisc method, ldisc_ops::fasync(), to notify line disciplines
when signal-driven I/O is enabled or disabled. When enabled for N_TTY
(by fcntl(F_SETFL, O_ASYNC)), blocking reader/polls will be woken
for any readable input. When disabled, blocking reader/polls are not
woken until the read buffer is full.
Canonical mode (L_ICANON(tty), n_tty_data::icanon) is not affected by
the minimum_to_wake setting.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index cdcdb0e..f1806de 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -89,6 +89,7 @@
int read_head;
int read_tail;
int read_cnt;
+ int minimum_to_wake;
unsigned char *echo_buf;
unsigned int echo_pos;
@@ -1455,7 +1456,7 @@
n_tty_set_room(tty);
- if ((!ldata->icanon && (ldata->read_cnt >= tty->minimum_to_wake)) ||
+ if ((!ldata->icanon && (ldata->read_cnt >= ldata->minimum_to_wake)) ||
L_EXTPROC(tty)) {
kill_fasync(&tty->fasync, SIGIO, POLL_IN);
if (waitqueue_active(&tty->read_wait))
@@ -1636,7 +1637,7 @@
tty->disc_data = ldata;
reset_buffer_flags(tty->disc_data);
ldata->column = 0;
- tty->minimum_to_wake = 1;
+ ldata->minimum_to_wake = 1;
tty->closing = 0;
/* indicate buffer work may resume */
clear_bit(TTY_LDISC_HALTED, &tty->flags);
@@ -1804,17 +1805,17 @@
minimum = MIN_CHAR(tty);
if (minimum) {
if (time)
- tty->minimum_to_wake = 1;
+ ldata->minimum_to_wake = 1;
else if (!waitqueue_active(&tty->read_wait) ||
- (tty->minimum_to_wake > minimum))
- tty->minimum_to_wake = minimum;
+ (ldata->minimum_to_wake > minimum))
+ ldata->minimum_to_wake = minimum;
} else {
timeout = 0;
if (time) {
timeout = time;
time = 0;
}
- tty->minimum_to_wake = minimum = 1;
+ ldata->minimum_to_wake = minimum = 1;
}
}
@@ -1854,9 +1855,9 @@
TASK_RUNNING. */
set_current_state(TASK_INTERRUPTIBLE);
- if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
+ if (((minimum - (b - buf)) < ldata->minimum_to_wake) &&
((minimum - (b - buf)) >= 1))
- tty->minimum_to_wake = (minimum - (b - buf));
+ ldata->minimum_to_wake = (minimum - (b - buf));
if (!input_available_p(tty, 0)) {
if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
@@ -1973,7 +1974,7 @@
remove_wait_queue(&tty->read_wait, &wait);
if (!waitqueue_active(&tty->read_wait))
- tty->minimum_to_wake = minimum;
+ ldata->minimum_to_wake = minimum;
__set_current_state(TASK_RUNNING);
size = b - buf;
@@ -2105,6 +2106,7 @@
static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
poll_table *wait)
{
+ struct n_tty_data *ldata = tty->disc_data;
unsigned int mask = 0;
poll_wait(file, &tty->read_wait, wait);
@@ -2119,9 +2121,9 @@
mask |= POLLHUP;
if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
if (MIN_CHAR(tty) && !TIME_CHAR(tty))
- tty->minimum_to_wake = MIN_CHAR(tty);
+ ldata->minimum_to_wake = MIN_CHAR(tty);
else
- tty->minimum_to_wake = 1;
+ ldata->minimum_to_wake = 1;
}
if (tty->ops->write && !tty_is_writelocked(tty) &&
tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
@@ -2169,6 +2171,18 @@
}
}
+static void n_tty_fasync(struct tty_struct *tty, int on)
+{
+ struct n_tty_data *ldata = tty->disc_data;
+
+ if (!waitqueue_active(&tty->read_wait)) {
+ if (on)
+ ldata->minimum_to_wake = 1;
+ else if (!tty->fasync)
+ ldata->minimum_to_wake = N_TTY_BUF_SIZE;
+ }
+}
+
struct tty_ldisc_ops tty_ldisc_N_TTY = {
.magic = TTY_LDISC_MAGIC,
.name = "n_tty",
@@ -2182,7 +2196,8 @@
.set_termios = n_tty_set_termios,
.poll = n_tty_poll,
.receive_buf = n_tty_receive_buf,
- .write_wakeup = n_tty_write_wakeup
+ .write_wakeup = n_tty_write_wakeup,
+ .fasync = n_tty_fasync,
};
/**