diff options
Diffstat (limited to 'drivers/tty/n_tty.c')
| -rw-r--r-- | drivers/tty/n_tty.c | 62 |
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; } |