TTY: move ldisc data from tty_struct: locks

atomic_write_lock is not n_tty specific, so move it up in the
tty_struct.

And since these are the last ones to move, remove also the comment
saying there are some ldisc' members. There are none now.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/tty_io.c

@@ -2939,11 +2939,7 @@ void initialize_tty_struct(struct tty_struct *tty,
 	init_waitqueue_head(&tty->write_wait);
 	init_waitqueue_head(&tty->read_wait);
 	INIT_WORK(&tty->hangup_work, do_tty_hangup);
-	mutex_init(&tty->atomic_read_lock);
 	mutex_init(&tty->atomic_write_lock);
-	mutex_init(&tty->output_lock);
-	mutex_init(&tty->echo_lock);
-	spin_lock_init(&tty->read_lock);
 	spin_lock_init(&tty->ctrl_lock);
 	INIT_LIST_HEAD(&tty->tty_files);
 	INIT_WORK(&tty->SAK_work, do_SAK_work);

include/linux/tty.h

@@ -235,6 +235,7 @@ struct tty_struct {
 	struct mutex ldisc_mutex;
 	struct tty_ldisc *ldisc;
 
+	struct mutex atomic_write_lock;
 	struct mutex legacy_mutex;
 	struct mutex termios_mutex;
 	spinlock_t ctrl_lock;
@@ -265,20 +266,10 @@ struct tty_struct {
 
 #define N_TTY_BUF_SIZE 4096
 
-	/*
-	 * The following is data for the N_TTY line discipline.  For
-	 * historical reasons, this is included in the tty structure.
-	 * Mostly locked by the BKL.
-	 */
 	unsigned char closing:1;
 	unsigned short minimum_to_wake;
-	struct mutex atomic_read_lock;
-	struct mutex atomic_write_lock;
-	struct mutex output_lock;
-	struct mutex echo_lock;
 	unsigned char *write_buf;
 	int write_cnt;
-	spinlock_t read_lock;
 	/* If the tty has a pending do_SAK, queue it here - akpm */
 	struct work_struct SAK_work;
 	struct tty_port *port;