From 9563dc59809550202301e588c88fcecf91191d3f Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Thu, 31 May 2012 11:35:18 +0200
Subject: [PATCH] --- yaml --- r: 309607 b: refs/heads/master c:
 fde86d310886372a377213251e72fb87aaa406c9 h: refs/heads/master i:   309605:
 39f8d65fc704d4a8e03cad9eba464ef0b5e39386   309603:
 dbabaf299138b40064e76efa445af0ddd6cdbfb1   309599:
 5f4b9ff7c551cdd735f7164342204d6ca4afc2e3 v: v3

---
 [refs]                        |  2 +-
 trunk/drivers/tty/tty_mutex.c | 19 +++++++++++++++----
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/[refs] b/[refs]
index 972cf5b689b4..2bb1c064cd1e 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 1d59d61f606547f0712aa6971f91f71154071c99
+refs/heads/master: fde86d310886372a377213251e72fb87aaa406c9
diff --git a/trunk/drivers/tty/tty_mutex.c b/trunk/drivers/tty/tty_mutex.c
index 69adc80c98cd..67feac9e6ebb 100644
--- a/trunk/drivers/tty/tty_mutex.c
+++ b/trunk/drivers/tty/tty_mutex.c
@@ -6,11 +6,17 @@
 
 /* Legacy tty mutex glue */
 
+enum {
+	TTY_MUTEX_NORMAL,
+	TTY_MUTEX_NESTED,
+};
+
 /*
  * Getting the big tty mutex.
  */
 
-void __lockfunc tty_lock(struct tty_struct *tty)
+static void __lockfunc tty_lock_nested(struct tty_struct *tty,
+				       unsigned int subclass)
 {
 	if (tty->magic != TTY_MAGIC) {
 		printk(KERN_ERR "L Bad %p\n", tty);
@@ -18,7 +24,12 @@ void __lockfunc tty_lock(struct tty_struct *tty)
 		return;
 	}
 	tty_kref_get(tty);
-	mutex_lock(&tty->legacy_mutex);
+	mutex_lock_nested(&tty->legacy_mutex, subclass);
+}
+
+void __lockfunc tty_lock(struct tty_struct *tty)
+{
+	return tty_lock_nested(tty, TTY_MUTEX_NORMAL);
 }
 EXPORT_SYMBOL(tty_lock);
 
@@ -43,11 +54,11 @@ void __lockfunc tty_lock_pair(struct tty_struct *tty,
 {
 	if (tty < tty2) {
 		tty_lock(tty);
-		tty_lock(tty2);
+		tty_lock_nested(tty2, TTY_MUTEX_NESTED);
 	} else {
 		if (tty2 && tty2 != tty)
 			tty_lock(tty2);
-		tty_lock(tty);
+		tty_lock_nested(tty, TTY_MUTEX_NESTED);
 	}
 }
 EXPORT_SYMBOL(tty_lock_pair);