TTY: remove tty_locked

We used it really only serial and ami_serial. The rest of the
callsites were BUG/WARN_ONs to check if BTM is held. Now that we
pruned tty_locked from both of the real users, we can get rid of
tty_lock along with __big_tty_mutex_owner.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

4 files changed, 2 insertions, 19 deletions

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 4786232bc532..44c29631b724 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1245,8 +1245,6 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
         struct uart_port *uport;
         unsigned long flags;
 
-        BUG_ON(!tty_locked());
-
         if (!state)
                 return;
 
@@ -1411,7 +1409,6 @@ static void uart_hangup(struct tty_struct *tty)
         struct tty_port *port = &state->port;
         unsigned long flags;
 
-        BUG_ON(!tty_locked());
         pr_debug("uart_hangup(%d)\n", state->uart_port->line);
 
         mutex_lock(&port->mutex);
@@ -1498,7 +1495,6 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
         struct tty_port *port;
         int retval, line = tty->index;
 
-        BUG_ON(!tty_locked());
         pr_debug("uart_open(%d) called\n", line);
 
         /*
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index ef925d581713..512c49f98e85 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -450,7 +450,6 @@ static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld)
         if (ld->ops->open) {
                 int ret;
                 /* BTM here locks versus a hangup event */
-                WARN_ON(!tty_locked());
                 ret = ld->ops->open(tty);
                 if (ret)
                         clear_bit(TTY_LDISC_OPEN, &tty->flags);
diff --git a/drivers/tty/tty_mutex.c b/drivers/tty/tty_mutex.c
index 3b2bb7719442..9ff986c32a21 100644
--- a/drivers/tty/tty_mutex.c
+++ b/drivers/tty/tty_mutex.c
@@ -15,30 +15,18 @@
  * Don't use in new code.
  */
 static DEFINE_MUTEX(big_tty_mutex);
-struct task_struct *__big_tty_mutex_owner;
-EXPORT_SYMBOL_GPL(__big_tty_mutex_owner);
 
 /*
  * Getting the big tty mutex.
  */
 void __lockfunc tty_lock(void)
 {
-        struct task_struct *task = current;
-
-        WARN_ON(__big_tty_mutex_owner == task);
-
         mutex_lock(&big_tty_mutex);
-        __big_tty_mutex_owner = task;
 }
 EXPORT_SYMBOL(tty_lock);
 
 void __lockfunc tty_unlock(void)
 {
-        struct task_struct *task = current;
-
-        WARN_ON(__big_tty_mutex_owner != task);
-        __big_tty_mutex_owner = NULL;
-
         mutex_unlock(&big_tty_mutex);
 }
 EXPORT_SYMBOL(tty_unlock);
diff --git a/drivers/tty/vt/selection.c b/drivers/tty/vt/selection.c
index fb864e7fcd13..7a0a12ae5458 100644
--- a/drivers/tty/vt/selection.c
+++ b/drivers/tty/vt/selection.c
@@ -301,6 +301,8 @@ int set_selection(const struct tiocl_selection __user *sel, struct tty_struct *t
 /* Insert the contents of the selection buffer into the
  * queue of the tty associated with the current console.
  * Invoked by ioctl().
+ *
+ * Locking: always called with BTM from vt_ioctl
  */
 int paste_selection(struct tty_struct *tty)
 {
@@ -310,8 +312,6 @@ int paste_selection(struct tty_struct *tty)
         struct  tty_ldisc *ld;
         DECLARE_WAITQUEUE(wait, current);
 
-        /* always called with BTM from vt_ioctl */
-        WARN_ON(!tty_locked());
 
         console_lock();
         poke_blanked_console();