diff options
Diffstat (limited to 'drivers/tty/n_tty.c')
| -rw-r--r-- | drivers/tty/n_tty.c | 29 |
1 files changed, 24 insertions, 5 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index ee1c268f5f9d..8c0b7b42319c 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -92,10 +92,18 @@ static inline int tty_put_user(struct tty_struct *tty, unsigned char x, 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 left; int old_left; + /* tty->read_cnt is not read locked ? */ + if (I_PARMRK(tty)) { + /* Multiply read_cnt by 3, since each byte might take up to + * three times as many spaces when PARMRK is set (depending on + * its flags, e.g. parity error). */ + left = N_TTY_BUF_SIZE - tty->read_cnt * 3 - 1; + } else + left = N_TTY_BUF_SIZE - tty->read_cnt - 1; + /* * If we are doing input canonicalization, and there are no * pending newlines, let characters through without limit, so @@ -1432,6 +1440,12 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp, */ if (tty->receive_room < TTY_THRESHOLD_THROTTLE) tty_throttle(tty); + + /* FIXME: there is a tiny race here if the receive room check runs + before the other work executes and empties the buffer (upping + the receiving room and unthrottling. We then throttle and get + stuck. This has been observed and traced down by Vincent Pillet/ + We need to address this when we sort out out the rx path locking */ } int is_ignored(int sig) @@ -1460,7 +1474,7 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old) BUG_ON(!tty); if (old) - canon_change = (old->c_lflag ^ tty->termios->c_lflag) & ICANON; + canon_change = (old->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; @@ -1728,7 +1742,8 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, do_it_again: - BUG_ON(!tty->read_buf); + if (WARN_ON(!tty->read_buf)) + return -EAGAIN; c = job_control(tty, file); if (c < 0) @@ -1832,13 +1847,13 @@ do_it_again: if (tty->icanon && !L_EXTPROC(tty)) { /* N.B. avoid overrun if nr == 0 */ + spin_lock_irqsave(&tty->read_lock, flags); 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--; @@ -1856,15 +1871,19 @@ do_it_again: if (tty_put_user(tty, c, b++)) { retval = -EFAULT; b--; + spin_lock_irqsave(&tty->read_lock, flags); break; } nr--; } if (eol) { tty_audit_push(tty); + spin_lock_irqsave(&tty->read_lock, flags); break; } + spin_lock_irqsave(&tty->read_lock, flags); } + spin_unlock_irqrestore(&tty->read_lock, flags); if (retval) break; } else { |