diff options
| author | Peter Hurley <peter@hurleysoftware.com> | 2014-11-05 12:13:05 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-11-05 18:50:42 -0800 |
| commit | 52bce7f8d4fc633c9a9d0646eef58ba6ae9a3b73 (patch) | |
| tree | 8d6586f5e62fcd0dbb4c54a64fe687939c79d1b6 /drivers/tty | |
| parent | 1bb954153aa97702db4363c6746794d097d9c707 (diff) | |
pty, n_tty: Simplify input processing on final close
When releasing one end of a pty pair, that end may just have written
to the other, which the input processing worker, flush_to_ldisc(), is
still working on but has not completed the copy to the other end's
read buffer. So input may not appear to be available to a waiting
reader but yet TTY_OTHER_CLOSED is now observed. The n_tty line
discipline has worked around this by waiting for input processing
to complete and then re-checking if input is available before
exiting with -EIO.
Since the tty/ldisc lock reordering, the wait for input processing
to complete can now occur during final close before setting
TTY_OTHER_CLOSED. In this way, a waiting reader is guaranteed to
see input available (if any) before observing TTY_OTHER_CLOSED.
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/n_tty.c | 46 | ||||
| -rw-r--r-- | drivers/tty/pty.c | 1 |
2 files changed, 21 insertions, 26 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 0cb0e12f87c7..112eda7c56bc 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -2197,34 +2197,28 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, if (!input_available_p(tty, 0)) { if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { - up_read(&tty->termios_rwsem); - tty_flush_to_ldisc(tty); - down_read(&tty->termios_rwsem); - if (!input_available_p(tty, 0)) { - retval = -EIO; - break; - } - } else { - 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); - up_read(&tty->termios_rwsem); + 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); + up_read(&tty->termios_rwsem); - timeout = schedule_timeout(timeout); + timeout = schedule_timeout(timeout); - down_read(&tty->termios_rwsem); - continue; - } + down_read(&tty->termios_rwsem); + continue; } __set_current_state(TASK_RUNNING); diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c index bee9776730fd..a9d256d6e909 100644 --- a/drivers/tty/pty.c +++ b/drivers/tty/pty.c @@ -53,6 +53,7 @@ static void pty_close(struct tty_struct *tty, struct file *filp) /* Review - krefs on tty_link ?? */ if (!tty->link) return; + tty_flush_to_ldisc(tty->link); set_bit(TTY_OTHER_CLOSED, &tty->link->flags); wake_up_interruptible(&tty->link->read_wait); wake_up_interruptible(&tty->link->write_wait); |