1 files changed, 31 insertions, 11 deletions

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 509efd49540f..592c576d77a7 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -70,6 +70,9 @@ static int graph_lock(void)
 
 static inline int graph_unlock(void)
 {
+        if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
+                return DEBUG_LOCKS_WARN_ON(1);
+
         __raw_spin_unlock(&lockdep_lock);
         return 0;
 }
@@ -487,7 +490,7 @@ static void print_lock_dependencies(struct lock_class *class, int depth)
  * Add a new dependency to the head of the list:
  */
 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
-                            struct list_head *head, unsigned long ip)
+                            struct list_head *head, unsigned long ip, int distance)
 {
         struct lock_list *entry;
         /*
@@ -499,6 +502,7 @@ static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
                 return 0;
 
         entry->class = this;
+        entry->distance = distance;
         if (!save_trace(&entry->trace))
                 return 0;
 
@@ -712,6 +716,9 @@ find_usage_backwards(struct lock_class *source, unsigned int depth)
         struct lock_list *entry;
         int ret;
 
+        if (!__raw_spin_is_locked(&lockdep_lock))
+                return DEBUG_LOCKS_WARN_ON(1);
+
         if (depth > max_recursion_depth)
                 max_recursion_depth = depth;
         if (depth >= RECURSION_LIMIT)
@@ -900,7 +907,7 @@ check_deadlock(struct task_struct *curr, struct held_lock *next,
  */
 static int
 check_prev_add(struct task_struct *curr, struct held_lock *prev,
-               struct held_lock *next)
+               struct held_lock *next, int distance)
 {
         struct lock_list *entry;
         int ret;
@@ -978,8 +985,11 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
          *  L2 added to its dependency list, due to the first chain.)
          */
         list_for_each_entry(entry, &prev->class->locks_after, entry) {
-                if (entry->class == next->class)
+                if (entry->class == next->class) {
+                        if (distance == 1)
+                                entry->distance = 1;
                         return 2;
+                }
         }
 
         /*
@@ -987,12 +997,13 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
          * to the previous lock's dependency list:
          */
         ret = add_lock_to_list(prev->class, next->class,
-                               &prev->class->locks_after, next->acquire_ip);
+                               &prev->class->locks_after, next->acquire_ip, distance);
+
         if (!ret)
                 return 0;
 
         ret = add_lock_to_list(next->class, prev->class,
-                               &next->class->locks_before, next->acquire_ip);
+                               &next->class->locks_before, next->acquire_ip, distance);
         if (!ret)
                 return 0;
 
@@ -1040,13 +1051,14 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
                 goto out_bug;
 
         for (;;) {
+                int distance = curr->lockdep_depth - depth + 1;
                 hlock = curr->held_locks + depth-1;
                 /*
                  * Only non-recursive-read entries get new dependencies
                  * added:
                  */
                 if (hlock->read != 2) {
-                        if (!check_prev_add(curr, hlock, next))
+                        if (!check_prev_add(curr, hlock, next, distance))
                                 return 0;
                         /*
                          * Stop after the first non-trylock entry,
@@ -1293,7 +1305,8 @@ out_unlock_set:
         if (!subclass || force)
                 lock->class_cache = class;
 
-        DEBUG_LOCKS_WARN_ON(class->subclass != subclass);
+        if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
+                return NULL;
 
         return class;
 }
@@ -1308,7 +1321,8 @@ static inline int lookup_chain_cache(u64 chain_key, struct lock_class *class)
         struct list_head *hash_head = chainhashentry(chain_key);
         struct lock_chain *chain;
 
-        DEBUG_LOCKS_WARN_ON(!irqs_disabled());
+        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+                return 0;
         /*
          * We can walk it lock-free, because entries only get added
          * to the hash:
@@ -1394,7 +1408,9 @@ static void check_chain_key(struct task_struct *curr)
                         return;
                 }
                 id = hlock->class - lock_classes;
-                DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS);
+                if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
+                        return;
+
                 if (prev_hlock && (prev_hlock->irq_context !=
                                                         hlock->irq_context))
                         chain_key = 0;
@@ -2205,7 +2221,11 @@ out_calc_hash:
                         if (!check_prevs_add(curr, hlock))
                                 return 0;
                 graph_unlock();
-        }
+        } else
+                /* after lookup_chain_cache(): */
+                if (unlikely(!debug_locks))
+                        return 0;
+
         curr->lockdep_depth++;
         check_chain_key(curr);
         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
@@ -2214,6 +2234,7 @@ out_calc_hash:
                 printk("turning off the locking correctness validator.\n");
                 return 0;
         }
+
         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
                 max_lockdep_depth = curr->lockdep_depth;
 
@@ -2764,4 +2785,3 @@ void debug_show_held_locks(struct task_struct *task)
 }
 
 EXPORT_SYMBOL_GPL(debug_show_held_locks);
-