• Peter Hurley's avatar
    pty, n_tty: Simplify input processing on final close · 52bce7f8
    Peter Hurley authored
    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: default avatarAlan Cox <alan@linux.intel.com>
    Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    52bce7f8
pty.c 22 KB