tty: Only guarantee termios read safety for throttle/unthrottle
No tty driver modifies termios during throttle() or unthrottle().
Therefore, only read safety is required.
However, tty_throttle_safe and tty_unthrottle_safe must still be
mutually exclusive; introduce throttle_mutex for that purpose.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/tty.h b/include/linux/tty.h
index d304207..57a70d1 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -244,6 +244,7 @@
struct mutex atomic_write_lock;
struct mutex legacy_mutex;
+ struct mutex throttle_mutex;
struct rw_semaphore termios_rwsem;
spinlock_t ctrl_lock;
/* Termios values are protected by the termios rwsem */