From 987af9903337f085046abe32bebccc47c9f0ba21 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <srostedt@redhat.com>
Date: Wed, 20 Apr 2011 21:41:56 -0400
Subject: [PATCH] --- yaml --- r: 245403 b: refs/heads/master c:
 48702ecf308e53f176c1f6fdc193d622ded54ac0 h: refs/heads/master i:   245401:
 01b31980886b4d440683d4c30942962521ab692b   245399:
 923960db21001001709a64bb9c86d80c9f18f0f7 v: v3

---
 [refs]                 |  2 +-
 trunk/kernel/lockdep.c | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 391c62f0a112..80c06c1857e6 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f4185812aa046ecb97e8817e10148cacdd7a6baa
+refs/heads/master: 48702ecf308e53f176c1f6fdc193d622ded54ac0
diff --git a/trunk/kernel/lockdep.c b/trunk/kernel/lockdep.c
index 73cebd7aa719..c4cc5d1acf48 100644
--- a/trunk/kernel/lockdep.c
+++ b/trunk/kernel/lockdep.c
@@ -1664,6 +1664,26 @@ static inline void inc_chains(void)
 
 #endif
 
+static void
+print_deadlock_scenario(struct held_lock *nxt,
+			     struct held_lock *prv)
+{
+	struct lock_class *next = hlock_class(nxt);
+	struct lock_class *prev = hlock_class(prv);
+
+	printk(" Possible unsafe locking scenario:\n\n");
+	printk("       CPU0\n");
+	printk("       ----\n");
+	printk("  lock(");
+	__print_lock_name(prev);
+	printk(");\n");
+	printk("  lock(");
+	__print_lock_name(next);
+	printk(");\n");
+	printk("\n *** DEADLOCK ***\n\n");
+	printk(" May be due to missing lock nesting notation\n\n");
+}
+
 static int
 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
 		   struct held_lock *next)
@@ -1682,6 +1702,7 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
 	print_lock(prev);
 
 	printk("\nother info that might help us debug this:\n");
+	print_deadlock_scenario(next, prev);
 	lockdep_print_held_locks(curr);
 
 	printk("\nstack backtrace:\n");