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path: root/drivers/tty/n_tty.c
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Diffstat (limited to 'drivers/tty/n_tty.c')
-rw-r--r--drivers/tty/n_tty.c62
1 files changed, 48 insertions, 14 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 95d0a9c2dd13..c3954fbf6ac4 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -81,6 +81,38 @@ static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
return put_user(x, ptr);
}
+/**
+ * n_tty_set__room - receive space
+ * @tty: terminal
+ *
+ * Called by the driver to find out how much data it is
+ * permitted to feed to the line discipline without any being lost
+ * and thus to manage flow control. Not serialized. Answers for the
+ * "instant".
+ */
+
+static void n_tty_set_room(struct tty_struct *tty)
+{
+ /* tty->read_cnt is not read locked ? */
+ int left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
+ int old_left;
+
+ /*
+ * If we are doing input canonicalization, and there are no
+ * pending newlines, let characters through without limit, so
+ * that erase characters will be handled. Other excess
+ * characters will be beeped.
+ */
+ if (left <= 0)
+ left = tty->icanon && !tty->canon_data;
+ old_left = tty->receive_room;
+ tty->receive_room = left;
+
+ /* Did this open up the receive buffer? We may need to flip */
+ if (left && !old_left)
+ schedule_work(&tty->buf.work);
+}
+
static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
{
if (tty->read_cnt < N_TTY_BUF_SIZE) {
@@ -152,6 +184,7 @@ static void reset_buffer_flags(struct tty_struct *tty)
tty->canon_head = tty->canon_data = tty->erasing = 0;
memset(&tty->read_flags, 0, sizeof tty->read_flags);
+ n_tty_set_room(tty);
check_unthrottle(tty);
}
@@ -1327,19 +1360,17 @@ static void n_tty_write_wakeup(struct tty_struct *tty)
* calls one at a time and in order (or using flush_to_ldisc)
*/
-static unsigned int n_tty_receive_buf(struct tty_struct *tty,
- const unsigned char *cp, char *fp, int count)
+static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
+ char *fp, int count)
{
const unsigned char *p;
char *f, flags = TTY_NORMAL;
int i;
char buf[64];
unsigned long cpuflags;
- int left;
- int ret = 0;
if (!tty->read_buf)
- return 0;
+ return;
if (tty->real_raw) {
spin_lock_irqsave(&tty->read_lock, cpuflags);
@@ -1349,7 +1380,6 @@ static unsigned int n_tty_receive_buf(struct tty_struct *tty,
memcpy(tty->read_buf + tty->read_head, cp, i);
tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
tty->read_cnt += i;
- ret += i;
cp += i;
count -= i;
@@ -1359,10 +1389,8 @@ static unsigned int n_tty_receive_buf(struct tty_struct *tty,
memcpy(tty->read_buf + tty->read_head, cp, i);
tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
tty->read_cnt += i;
- ret += i;
spin_unlock_irqrestore(&tty->read_lock, cpuflags);
} else {
- ret = count;
for (i = count, p = cp, f = fp; i; i--, p++) {
if (f)
flags = *f++;
@@ -1390,6 +1418,8 @@ static unsigned int n_tty_receive_buf(struct tty_struct *tty,
tty->ops->flush_chars(tty);
}
+ n_tty_set_room(tty);
+
if ((!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) ||
L_EXTPROC(tty)) {
kill_fasync(&tty->fasync, SIGIO, POLL_IN);
@@ -1402,12 +1432,8 @@ static unsigned int n_tty_receive_buf(struct tty_struct *tty,
* mode. We don't want to throttle the driver if we're in
* canonical mode and don't have a newline yet!
*/
- left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
-
- if (left < TTY_THRESHOLD_THROTTLE)
+ if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
tty_throttle(tty);
-
- return ret;
}
int is_ignored(int sig)
@@ -1451,6 +1477,7 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
tty->raw = 1;
tty->real_raw = 1;
+ n_tty_set_room(tty);
return;
}
if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
@@ -1503,6 +1530,7 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
else
tty->real_raw = 0;
}
+ n_tty_set_room(tty);
/* The termios change make the tty ready for I/O */
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->read_wait);
@@ -1784,7 +1812,10 @@ do_it_again:
retval = -ERESTARTSYS;
break;
}
+ /* FIXME: does n_tty_set_room need locking ? */
+ n_tty_set_room(tty);
timeout = schedule_timeout(timeout);
+ BUG_ON(!tty->read_buf);
continue;
}
__set_current_state(TASK_RUNNING);
@@ -1855,8 +1886,10 @@ do_it_again:
* 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)
+ if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
+ n_tty_set_room(tty);
check_unthrottle(tty);
+ }
if (b - buf >= minimum)
break;
@@ -1878,6 +1911,7 @@ do_it_again:
} else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
goto do_it_again;
+ n_tty_set_room(tty);
return retval;
}