From f51ccf46217c28758b1f3b5bc0ccfc00eca658b2 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Tue, 4 Dec 2018 17:00:36 +0100 Subject: USB: serial: console: fix reported terminal settings The USB-serial console implementation has never reported the actual terminal settings used. Despite storing the corresponding cflags in its struct console, these were never honoured on later tty open() where the tty termios would be left initialised to the driver defaults. Unlike the serial console implementation, the USB-serial code calls subdriver open() already at console setup. While calling set_termios() and write() before open() looks like it could work for some USB-serial drivers, others definitely do not expect this, so modelling this after serial core is going to be intrusive, if at all possible. Instead, use a (renamed) tty helper to save the termios data used at console setup so that the tty termios reflects the actual terminal settings after a subsequent tty open(). Note that the calls to tty_init_termios() (tty_driver_install()) and tty_save_termios() are serialised using the disconnect mutex. This specifically fixes a regression that was triggered by a recent change adding software flow control to the pl2303 driver: a getty trying to disable flow control while leaving the baud rate unchanged would now also set the baud rate to the driver default (prior to the flow-control change this had been a noop). Fixes: 7041d9c3f01b ("USB: serial: pl2303: add support for tx xon/xoff flow control") Cc: stable # 4.18 Cc: Florian Zumbiehl Reported-by: Jarkko Nikula Tested-by: Jarkko Nikula Acked-by: Greg Kroah-Hartman Signed-off-by: Johan Hovold --- drivers/tty/tty_io.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'drivers/tty') diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index ee80dfbd5442..687250ec8032 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -1373,7 +1373,13 @@ err_release_lock: return ERR_PTR(retval); } -static void tty_free_termios(struct tty_struct *tty) +/** + * tty_save_termios() - save tty termios data in driver table + * @tty: tty whose termios data to save + * + * Locking: Caller guarantees serialisation with tty_init_termios(). + */ +void tty_save_termios(struct tty_struct *tty) { struct ktermios *tp; int idx = tty->index; @@ -1392,6 +1398,7 @@ static void tty_free_termios(struct tty_struct *tty) } *tp = tty->termios; } +EXPORT_SYMBOL_GPL(tty_save_termios); /** * tty_flush_works - flush all works of a tty/pty pair @@ -1491,7 +1498,7 @@ static void release_tty(struct tty_struct *tty, int idx) WARN_ON(!mutex_is_locked(&tty_mutex)); if (tty->ops->shutdown) tty->ops->shutdown(tty); - tty_free_termios(tty); + tty_save_termios(tty); tty_driver_remove_tty(tty->driver, tty); tty->port->itty = NULL; if (tty->link) -- cgit v1.2.3