X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=drivers%2Ftty%2Ftty_mutex.c;h=d09293bc0e041417cc15047f84eec0ccd01298eb;hb=58594a804233d863ee344adf7554571d831f6c23;hp=4486741190c47d52d8079f360081d99085ce82c4;hpb=32c9edc4e356063e0218362d452a269cfa6798ee;p=firefly-linux-kernel-4.4.55.git

diff --git a/drivers/tty/tty_mutex.c b/drivers/tty/tty_mutex.c
index 4486741190c4..d09293bc0e04 100644
--- a/drivers/tty/tty_mutex.c
+++ b/drivers/tty/tty_mutex.c
@@ -4,18 +4,8 @@
 #include <linux/semaphore.h>
 #include <linux/sched.h>
 
-/*
- * Nested tty locks are necessary for releasing pty pairs.
- * The stable lock order is master pty first, then slave pty.
- */
-
 /* Legacy tty mutex glue */
 
-enum {
-	TTY_MUTEX_NORMAL,
-	TTY_MUTEX_SLAVE,
-};
-
 /*
  * Getting the big tty mutex.
  */
@@ -32,6 +22,14 @@ void __lockfunc tty_lock(struct tty_struct *tty)
 }
 EXPORT_SYMBOL(tty_lock);
 
+int tty_lock_interruptible(struct tty_struct *tty)
+{
+	if (WARN(tty->magic != TTY_MAGIC, "L Bad %p\n", tty))
+		return -EIO;
+	tty_kref_get(tty);
+	return mutex_lock_interruptible(&tty->legacy_mutex);
+}
+
 void __lockfunc tty_unlock(struct tty_struct *tty)
 {
 	if (tty->magic != TTY_MAGIC) {
@@ -46,12 +44,8 @@ EXPORT_SYMBOL(tty_unlock);
 
 void __lockfunc tty_lock_slave(struct tty_struct *tty)
 {
-	if (tty && tty != tty->link) {
-		WARN_ON(!mutex_is_locked(&tty->link->legacy_mutex) ||
-			!tty->driver->type == TTY_DRIVER_TYPE_PTY ||
-			!tty->driver->type == PTY_TYPE_SLAVE);
+	if (tty && tty != tty->link)
 		tty_lock(tty);
-	}
 }
 
 void __lockfunc tty_unlock_slave(struct tty_struct *tty)
@@ -62,5 +56,5 @@ void __lockfunc tty_unlock_slave(struct tty_struct *tty)
 
 void tty_set_lock_subclass(struct tty_struct *tty)
 {
-	lockdep_set_subclass(&tty->legacy_mutex, TTY_MUTEX_SLAVE);
+	lockdep_set_subclass(&tty->legacy_mutex, TTY_LOCK_SLAVE);
 }