vt: Grab console_lock around con_is_bound in show_bind

Not really harmful not to, but also not harm in grabbing the lock. And
this shuts up a new WARNING I introduced in commit ddde3c1 ("vt:
More locking checks").

Reported-by: Jens Remus <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Nicolas Pitre <[email protected]>
Cc: Martin Hostettler <[email protected]>
Cc: Adam Borowski <[email protected]>
Cc: Mikulas Patocka <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Fixes: ddde3c1 ("vt: More locking checks")
Signed-off-by: Daniel Vetter <[email protected]>
Tested-by: Jens Remus <[email protected]>
Acked-by: Sam Ravnborg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: danvet

drivers/tty/vt/vt.c

@@ -3771,7 +3771,11 @@ static ssize_t show_bind(struct device *dev, struct device_attribute *attr,
 			 char *buf)
 {
 	struct con_driver *con = dev_get_drvdata(dev);
-	int bind = con_is_bound(con->con);
+	int bind;
+
+	console_lock();
+	bind = con_is_bound(con->con);
+	console_unlock();
 
 	return snprintf(buf, PAGE_SIZE, "%i\n", bind);
 }