1 files changed, 57 insertions, 75 deletions

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 716547f..f894a2c 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -123,8 +123,6 @@ static inline int debug_locks_off_graph_unlock(void)
 	return ret;
 }
 
-static int lockdep_initialized;
-
 unsigned long nr_list_entries;
 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
 
@@ -434,19 +432,6 @@ unsigned int max_lockdep_depth;
 
 #ifdef CONFIG_DEBUG_LOCKDEP
 /*
- * We cannot printk in early bootup code. Not even early_printk()
- * might work. So we mark any initialization errors and printk
- * about it later on, in lockdep_info().
- */
-static int lockdep_init_error;
-static const char *lock_init_error;
-static unsigned long lockdep_init_trace_data[20];
-static struct stack_trace lockdep_init_trace = {
-	.max_entries = ARRAY_SIZE(lockdep_init_trace_data),
-	.entries = lockdep_init_trace_data,
-};
-
-/*
  * Various lockdep statistics:
  */
 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
@@ -669,20 +654,6 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
 	struct hlist_head *hash_head;
 	struct lock_class *class;
 
-#ifdef CONFIG_DEBUG_LOCKDEP
-	/*
-	 * If the architecture calls into lockdep before initializing
-	 * the hashes then we'll warn about it later. (we cannot printk
-	 * right now)
-	 */
-	if (unlikely(!lockdep_initialized)) {
-		lockdep_init();
-		lockdep_init_error = 1;
-		lock_init_error = lock->name;
-		save_stack_trace(&lockdep_init_trace);
-	}
-#endif
-
 	if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
 		debug_locks_off();
 		printk(KERN_ERR
@@ -2011,6 +1982,53 @@ struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
 }
 
 /*
+ * Returns the index of the first held_lock of the current chain
+ */
+static inline int get_first_held_lock(struct task_struct *curr,
+					struct held_lock *hlock)
+{
+	int i;
+	struct held_lock *hlock_curr;
+
+	for (i = curr->lockdep_depth - 1; i >= 0; i--) {
+		hlock_curr = curr->held_locks + i;
+		if (hlock_curr->irq_context != hlock->irq_context)
+			break;
+
+	}
+
+	return ++i;
+}
+
+/*
+ * Checks whether the chain and the current held locks are consistent
+ * in depth and also in content. If they are not it most likely means
+ * that there was a collision during the calculation of the chain_key.
+ * Returns: 0 not passed, 1 passed
+ */
+static int check_no_collision(struct task_struct *curr,
+			struct held_lock *hlock,
+			struct lock_chain *chain)
+{
+#ifdef CONFIG_DEBUG_LOCKDEP
+	int i, j, id;
+
+	i = get_first_held_lock(curr, hlock);
+
+	if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1)))
+		return 0;
+
+	for (j = 0; j < chain->depth - 1; j++, i++) {
+		id = curr->held_locks[i].class_idx - 1;
+
+		if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id))
+			return 0;
+	}
+#endif
+	return 1;
+}
+
+/*
  * Look up a dependency chain. If the key is not present yet then
  * add it and return 1 - in this case the new dependency chain is
  * validated. If the key is already hashed, return 0.
@@ -2023,7 +2041,6 @@ static inline int lookup_chain_cache(struct task_struct *curr,
 	struct lock_class *class = hlock_class(hlock);
 	struct hlist_head *hash_head = chainhashentry(chain_key);
 	struct lock_chain *chain;
-	struct held_lock *hlock_curr;
 	int i, j;
 
 	/*
@@ -2041,6 +2058,9 @@ static inline int lookup_chain_cache(struct task_struct *curr,
 		if (chain->chain_key == chain_key) {
 cache_hit:
 			debug_atomic_inc(chain_lookup_hits);
+			if (!check_no_collision(curr, hlock, chain))
+				return 0;
+
 			if (very_verbose(class))
 				printk("\nhash chain already cached, key: "
 					"%016Lx tail class: [%p] %s\n",
@@ -2078,13 +2098,7 @@ cache_hit:
 	chain = lock_chains + nr_lock_chains++;
 	chain->chain_key = chain_key;
 	chain->irq_context = hlock->irq_context;
-	/* Find the first held_lock of current chain */
-	for (i = curr->lockdep_depth - 1; i >= 0; i--) {
-		hlock_curr = curr->held_locks + i;
-		if (hlock_curr->irq_context != hlock->irq_context)
-			break;
-	}
-	i++;
+	i = get_first_held_lock(curr, hlock);
 	chain->depth = curr->lockdep_depth + 1 - i;
 	if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
 		chain->base = nr_chain_hlocks;
@@ -2172,7 +2186,7 @@ static void check_chain_key(struct task_struct *curr)
 {
 #ifdef CONFIG_DEBUG_LOCKDEP
 	struct held_lock *hlock, *prev_hlock = NULL;
-	unsigned int i, id;
+	unsigned int i;
 	u64 chain_key = 0;
 
 	for (i = 0; i < curr->lockdep_depth; i++) {
@@ -2189,17 +2203,16 @@ static void check_chain_key(struct task_struct *curr)
 				(unsigned long long)hlock->prev_chain_key);
 			return;
 		}
-		id = hlock->class_idx - 1;
 		/*
 		 * Whoops ran out of static storage again?
 		 */
-		if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
+		if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
 			return;
 
 		if (prev_hlock && (prev_hlock->irq_context !=
 							hlock->irq_context))
 			chain_key = 0;
-		chain_key = iterate_chain_key(chain_key, id);
+		chain_key = iterate_chain_key(chain_key, hlock->class_idx);
 		prev_hlock = hlock;
 	}
 	if (chain_key != curr->curr_chain_key) {
@@ -3077,7 +3090,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 	struct task_struct *curr = current;
 	struct lock_class *class = NULL;
 	struct held_lock *hlock;
-	unsigned int depth, id;
+	unsigned int depth;
 	int chain_head = 0;
 	int class_idx;
 	u64 chain_key;
@@ -3180,11 +3193,10 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 	 * The 'key ID' is what is the most compact key value to drive
 	 * the hash, not class->key.
 	 */
-	id = class - lock_classes;
 	/*
 	 * Whoops, we did it again.. ran straight out of our static allocation.
 	 */
-	if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
+	if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
 		return 0;
 
 	chain_key = curr->curr_chain_key;
@@ -3202,7 +3214,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 		chain_key = 0;
 		chain_head = 1;
 	}
-	chain_key = iterate_chain_key(chain_key, id);
+	chain_key = iterate_chain_key(chain_key, class_idx);
 
 	if (nest_lock && !__lock_is_held(nest_lock))
 		return print_lock_nested_lock_not_held(curr, hlock, ip);
@@ -4013,28 +4025,6 @@ out_restore:
 	raw_local_irq_restore(flags);
 }
 
-void lockdep_init(void)
-{
-	int i;
-
-	/*
-	 * Some architectures have their own start_kernel()
-	 * code which calls lockdep_init(), while we also
-	 * call lockdep_init() from the start_kernel() itself,
-	 * and we want to initialize the hashes only once:
-	 */
-	if (lockdep_initialized)
-		return;
-
-	for (i = 0; i < CLASSHASH_SIZE; i++)
-		INIT_HLIST_HEAD(classhash_table + i);
-
-	for (i = 0; i < CHAINHASH_SIZE; i++)
-		INIT_HLIST_HEAD(chainhash_table + i);
-
-	lockdep_initialized = 1;
-}
-
 void __init lockdep_info(void)
 {
 	printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
@@ -4061,14 +4051,6 @@ void __init lockdep_info(void)
 
 	printk(" per task-struct memory footprint: %lu bytes\n",
 		sizeof(struct held_lock) * MAX_LOCK_DEPTH);
-
-#ifdef CONFIG_DEBUG_LOCKDEP
-	if (lockdep_init_error) {
-		printk("WARNING: lockdep init error: lock '%s' was acquired before lockdep_init().\n", lock_init_error);
-		printk("Call stack leading to lockdep invocation was:\n");
-		print_stack_trace(&lockdep_init_trace, 0);
-	}
-#endif
 }
 
 static void