tty: Convert termios_mutex to termios_rwsem
termios is commonly accessed unsafely (especially by N_TTY)
because the existing mutex forces exclusive access.
Convert existing usage.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index e52d6157..6458e11 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -415,14 +415,14 @@
* they are not on hot paths so a little discipline won't do
* any harm.
*
- * Locking: takes termios_mutex
+ * Locking: takes termios_rwsem
*/
static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
{
- mutex_lock(&tty->termios_mutex);
+ down_write(&tty->termios_rwsem);
tty->termios.c_line = num;
- mutex_unlock(&tty->termios_mutex);
+ up_write(&tty->termios_rwsem);
}
/**
@@ -602,11 +602,11 @@
static void tty_reset_termios(struct tty_struct *tty)
{
- mutex_lock(&tty->termios_mutex);
+ down_write(&tty->termios_rwsem);
tty->termios = tty->driver->init_termios;
tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
- mutex_unlock(&tty->termios_mutex);
+ up_write(&tty->termios_rwsem);
}