4.19-stable review patch. If anyone has any objections, please let me know.
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From: Johan Hovold johan@kernel.org
commit f51ccf46217c28758b1f3b5bc0ccfc00eca658b2 upstream.
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 stable@vger.kernel.org # 4.18 Cc: Florian Zumbiehl florz@florz.de Reported-by: Jarkko Nikula jarkko.nikula@linux.intel.com Tested-by: Jarkko Nikula jarkko.nikula@linux.intel.com Acked-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Johan Hovold johan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/tty/tty_io.c | 11 +++++++++-- drivers/usb/serial/console.c | 2 +- include/linux/tty.h | 1 + 3 files changed, 11 insertions(+), 3 deletions(-)
--- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -1372,7 +1372,13 @@ 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; @@ -1391,6 +1397,7 @@ static void tty_free_termios(struct tty_ } *tp = tty->termios; } +EXPORT_SYMBOL_GPL(tty_save_termios);
/** * tty_flush_works - flush all works of a tty/pty pair @@ -1490,7 +1497,7 @@ static void release_tty(struct tty_struc 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) --- a/drivers/usb/serial/console.c +++ b/drivers/usb/serial/console.c @@ -101,7 +101,6 @@ static int usb_console_setup(struct cons cflag |= PARENB; break; } - co->cflag = cflag;
/* * no need to check the index here: if the index is wrong, console @@ -164,6 +163,7 @@ static int usb_console_setup(struct cons serial->type->set_termios(tty, port, &dummy);
tty_port_tty_set(&port->port, NULL); + tty_save_termios(tty); tty_kref_put(tty); } tty_port_set_initialized(&port->port, 1); --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -556,6 +556,7 @@ extern struct tty_struct *tty_init_dev(s extern void tty_release_struct(struct tty_struct *tty, int idx); extern int tty_release(struct inode *inode, struct file *filp); extern void tty_init_termios(struct tty_struct *tty); +extern void tty_save_termios(struct tty_struct *tty); extern int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty);