X-Git-Url: http://git.rot13.org/?a=blobdiff_plain;f=kernel%2Flockdep.c;h=8dc24c92dc6d2c1e867c8ce381caec43c9408583;hb=de74f70360353929009f8611f3bb8fbb4f030527;hp=b02032476dc2e88967940060a84b5bc5742f1a5e;hpb=ea14fad0d416354a4e9bb1a04f32acba706f9548;p=powerpc.git

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index b02032476d..8dc24c92dc 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -43,13 +43,52 @@
 #include "lockdep_internals.h"
 
 /*
- * hash_lock: protects the lockdep hashes and class/list/hash allocators.
+ * lockdep_lock: protects the lockdep graph, the hashes and the
+ *               class/list/hash allocators.
  *
  * This is one of the rare exceptions where it's justified
  * to use a raw spinlock - we really dont want the spinlock
- * code to recurse back into the lockdep code.
+ * code to recurse back into the lockdep code...
  */
-static raw_spinlock_t hash_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
+static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
+
+static int graph_lock(void)
+{
+	__raw_spin_lock(&lockdep_lock);
+	/*
+	 * Make sure that if another CPU detected a bug while
+	 * walking the graph we dont change it (while the other
+	 * CPU is busy printing out stuff with the graph lock
+	 * dropped already)
+	 */
+	if (!debug_locks) {
+		__raw_spin_unlock(&lockdep_lock);
+		return 0;
+	}
+	return 1;
+}
+
+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;
+}
+
+/*
+ * Turn lock debugging off and return with 0 if it was off already,
+ * and also release the graph lock:
+ */
+static inline int debug_locks_off_graph_unlock(void)
+{
+	int ret = debug_locks_off();
+
+	__raw_spin_unlock(&lockdep_lock);
+
+	return ret;
+}
 
 static int lockdep_initialized;
 
@@ -57,14 +96,15 @@ unsigned long nr_list_entries;
 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
 
 /*
- * Allocate a lockdep entry. (assumes hash_lock held, returns
+ * Allocate a lockdep entry. (assumes the graph_lock held, returns
  * with NULL on failure)
  */
 static struct lock_list *alloc_list_entry(void)
 {
 	if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
-		__raw_spin_unlock(&hash_lock);
-		debug_locks_off();
+		if (!debug_locks_off_graph_unlock())
+			return NULL;
+
 		printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
 		printk("turning off the locking correctness validator.\n");
 		return NULL;
@@ -145,9 +185,7 @@ EXPORT_SYMBOL(lockdep_on);
  */
 
 #define VERBOSE			0
-#ifdef VERBOSE
-# define VERY_VERBOSE		0
-#endif
+#define VERY_VERBOSE		0
 
 #if VERBOSE
 # define HARDIRQ_VERBOSE	1
@@ -172,8 +210,8 @@ static int class_filter(struct lock_class *class)
 			!strcmp(class->name, "&struct->lockfield"))
 		return 1;
 #endif
-	/* Allow everything else. 0 would be filter everything else */
-	return 1;
+	/* Filter everything else. 1 would be to allow everything else */
+	return 0;
 }
 #endif
 
@@ -207,7 +245,7 @@ static int softirq_verbose(struct lock_class *class)
 
 /*
  * Stack-trace: tightly packed array of stack backtrace
- * addresses. Protected by the hash_lock.
+ * addresses. Protected by the graph_lock.
  */
 unsigned long nr_stack_trace_entries;
 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
@@ -226,18 +264,15 @@ static int save_trace(struct stack_trace *trace)
 	trace->max_entries = trace->nr_entries;
 
 	nr_stack_trace_entries += trace->nr_entries;
-	if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries > MAX_STACK_TRACE_ENTRIES)) {
-		__raw_spin_unlock(&hash_lock);
-		return 0;
-	}
 
 	if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
-		__raw_spin_unlock(&hash_lock);
-		if (debug_locks_off()) {
-			printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
-			printk("turning off the locking correctness validator.\n");
-			dump_stack();
-		}
+		if (!debug_locks_off_graph_unlock())
+			return 0;
+
+		printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
+		printk("turning off the locking correctness validator.\n");
+		dump_stack();
+
 		return 0;
 	}
 
@@ -455,7 +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;
 	/*
@@ -467,6 +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;
 
@@ -526,9 +562,7 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth)
 {
 	struct task_struct *curr = current;
 
-	__raw_spin_unlock(&hash_lock);
-	debug_locks_off();
-	if (debug_locks_silent)
+	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
 		return 0;
 
 	printk("\n=======================================================\n");
@@ -556,12 +590,10 @@ static noinline int print_circular_bug_tail(void)
 	if (debug_locks_silent)
 		return 0;
 
-	/* hash_lock unlocked by the header */
-	__raw_spin_lock(&hash_lock);
 	this.class = check_source->class;
 	if (!save_trace(&this.trace))
 		return 0;
-	__raw_spin_unlock(&hash_lock);
+
 	print_circular_bug_entry(&this, 0);
 
 	printk("\nother info that might help us debug this:\n\n");
@@ -577,8 +609,10 @@ static noinline int print_circular_bug_tail(void)
 
 static int noinline print_infinite_recursion_bug(void)
 {
-	__raw_spin_unlock(&hash_lock);
-	DEBUG_LOCKS_WARN_ON(1);
+	if (!debug_locks_off_graph_unlock())
+		return 0;
+
+	WARN_ON(1);
 
 	return 0;
 }
@@ -682,6 +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)
@@ -713,9 +750,7 @@ print_bad_irq_dependency(struct task_struct *curr,
 			 enum lock_usage_bit bit2,
 			 const char *irqclass)
 {
-	__raw_spin_unlock(&hash_lock);
-	debug_locks_off();
-	if (debug_locks_silent)
+	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
 		return 0;
 
 	printk("\n======================================================\n");
@@ -796,9 +831,7 @@ static int
 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
 		   struct held_lock *next)
 {
-	debug_locks_off();
-	__raw_spin_unlock(&hash_lock);
-	if (debug_locks_silent)
+	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
 		return 0;
 
 	printk("\n=============================================\n");
@@ -874,7 +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;
@@ -952,8 +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;
+		}
 	}
 
 	/*
@@ -961,12 +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;
 
@@ -974,14 +1011,14 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
 	 * Debugging printouts:
 	 */
 	if (verbose(prev->class) || verbose(next->class)) {
-		__raw_spin_unlock(&hash_lock);
+		graph_unlock();
 		printk("\n new dependency: ");
 		print_lock_name(prev->class);
 		printk(" => ");
 		print_lock_name(next->class);
 		printk("\n");
 		dump_stack();
-		__raw_spin_lock(&hash_lock);
+		return graph_lock();
 	}
 	return 1;
 }
@@ -1014,13 +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,
@@ -1046,8 +1084,10 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
 	}
 	return 1;
 out_bug:
-	__raw_spin_unlock(&hash_lock);
-	DEBUG_LOCKS_WARN_ON(1);
+	if (!debug_locks_off_graph_unlock())
+		return 0;
+
+	WARN_ON(1);
 
 	return 0;
 }
@@ -1201,7 +1241,10 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 	hash_head = classhashentry(key);
 
 	raw_local_irq_save(flags);
-	__raw_spin_lock(&hash_lock);
+	if (!graph_lock()) {
+		raw_local_irq_restore(flags);
+		return NULL;
+	}
 	/*
 	 * We have to do the hash-walk again, to avoid races
 	 * with another CPU:
@@ -1214,9 +1257,12 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 	 * the hash:
 	 */
 	if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
-		__raw_spin_unlock(&hash_lock);
+		if (!debug_locks_off_graph_unlock()) {
+			raw_local_irq_restore(flags);
+			return NULL;
+		}
 		raw_local_irq_restore(flags);
-		debug_locks_off();
+
 		printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
 		printk("turning off the locking correctness validator.\n");
 		return NULL;
@@ -1237,24 +1283,30 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 	list_add_tail_rcu(&class->hash_entry, hash_head);
 
 	if (verbose(class)) {
-		__raw_spin_unlock(&hash_lock);
+		graph_unlock();
 		raw_local_irq_restore(flags);
+
 		printk("\nnew class %p: %s", class->key, class->name);
 		if (class->name_version > 1)
 			printk("#%d", class->name_version);
 		printk("\n");
 		dump_stack();
+
 		raw_local_irq_save(flags);
-		__raw_spin_lock(&hash_lock);
+		if (!graph_lock()) {
+			raw_local_irq_restore(flags);
+			return NULL;
+		}
 	}
 out_unlock_set:
-	__raw_spin_unlock(&hash_lock);
+	graph_unlock();
 	raw_local_irq_restore(flags);
 
 	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;
 }
@@ -1264,12 +1316,13 @@ out_unlock_set:
  * add it and return 0 - in this case the new dependency chain is
  * validated. If the key is already hashed, return 1.
  */
-static inline int lookup_chain_cache(u64 chain_key)
+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:
@@ -1278,34 +1331,36 @@ static inline int lookup_chain_cache(u64 chain_key)
 		if (chain->chain_key == chain_key) {
 cache_hit:
 			debug_atomic_inc(&chain_lookup_hits);
-			/*
-			 * In the debugging case, force redundant checking
-			 * by returning 1:
-			 */
-#ifdef CONFIG_DEBUG_LOCKDEP
-			__raw_spin_lock(&hash_lock);
-			return 1;
-#endif
+			if (very_verbose(class))
+				printk("\nhash chain already cached, key: "
+					"%016Lx tail class: [%p] %s\n",
+					(unsigned long long)chain_key,
+					class->key, class->name);
 			return 0;
 		}
 	}
+	if (very_verbose(class))
+		printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
+			(unsigned long long)chain_key, class->key, class->name);
 	/*
 	 * Allocate a new chain entry from the static array, and add
 	 * it to the hash:
 	 */
-	__raw_spin_lock(&hash_lock);
+	if (!graph_lock())
+		return 0;
 	/*
 	 * We have to walk the chain again locked - to avoid duplicates:
 	 */
 	list_for_each_entry(chain, hash_head, entry) {
 		if (chain->chain_key == chain_key) {
-			__raw_spin_unlock(&hash_lock);
+			graph_unlock();
 			goto cache_hit;
 		}
 	}
 	if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
-		__raw_spin_unlock(&hash_lock);
-		debug_locks_off();
+		if (!debug_locks_off_graph_unlock())
+			return 0;
+
 		printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
 		printk("turning off the locking correctness validator.\n");
 		return 0;
@@ -1353,7 +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;
@@ -1381,9 +1438,7 @@ print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
 			struct held_lock *this, int forwards,
 			const char *irqclass)
 {
-	__raw_spin_unlock(&hash_lock);
-	debug_locks_off();
-	if (debug_locks_silent)
+	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
 		return 0;
 
 	printk("\n=========================================================\n");
@@ -1453,7 +1508,7 @@ check_usage_backwards(struct task_struct *curr, struct held_lock *this,
 	return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
 }
 
-static inline void print_irqtrace_events(struct task_struct *curr)
+void print_irqtrace_events(struct task_struct *curr)
 {
 	printk("irq event stamp: %u\n", curr->irq_events);
 	printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
@@ -1466,19 +1521,13 @@ static inline void print_irqtrace_events(struct task_struct *curr)
 	print_ip_sym(curr->softirq_disable_ip);
 }
 
-#else
-static inline void print_irqtrace_events(struct task_struct *curr)
-{
-}
 #endif
 
 static int
 print_usage_bug(struct task_struct *curr, struct held_lock *this,
 		enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
 {
-	__raw_spin_unlock(&hash_lock);
-	debug_locks_off();
-	if (debug_locks_silent)
+	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
 		return 0;
 
 	printk("\n=================================\n");
@@ -1539,12 +1588,13 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
 	if (likely(this->class->usage_mask & new_mask))
 		return 1;
 
-	__raw_spin_lock(&hash_lock);
+	if (!graph_lock())
+		return 0;
 	/*
 	 * Make sure we didnt race:
 	 */
 	if (unlikely(this->class->usage_mask & new_mask)) {
-		__raw_spin_unlock(&hash_lock);
+		graph_unlock();
 		return 1;
 	}
 
@@ -1730,16 +1780,16 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
 		debug_atomic_dec(&nr_unused_locks);
 		break;
 	default:
-		__raw_spin_unlock(&hash_lock);
-		debug_locks_off();
+		if (!debug_locks_off_graph_unlock())
+			return 0;
 		WARN_ON(1);
 		return 0;
 	}
 
-	__raw_spin_unlock(&hash_lock);
+	graph_unlock();
 
 	/*
-	 * We must printk outside of the hash_lock:
+	 * We must printk outside of the graph_lock:
 	 */
 	if (ret == 2) {
 		printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
@@ -2137,9 +2187,9 @@ out_calc_hash:
 	 * We look up the chain_key and do the O(N^2) check and update of
 	 * the dependencies only if this is a new dependency chain.
 	 * (If lookup_chain_cache() returns with 1 it acquires
-	 * hash_lock for us)
+	 * graph_lock for us)
 	 */
-	if (!trylock && (check == 2) && lookup_chain_cache(chain_key)) {
+	if (!trylock && (check == 2) && lookup_chain_cache(chain_key, class)) {
 		/*
 		 * Check whether last held lock:
 		 *
@@ -2170,16 +2220,25 @@ out_calc_hash:
 		if (!chain_head && ret != 2)
 			if (!check_prevs_add(curr, hlock))
 				return 0;
-		__raw_spin_unlock(&hash_lock);
-	}
+		graph_unlock();
+	} else
+		/* after lookup_chain_cache(): */
+		if (unlikely(!debug_locks))
+			return 0;
+
 	curr->lockdep_depth++;
 	check_chain_key(curr);
+#ifdef CONFIG_DEBUG_LOCKDEP
+	if (unlikely(!debug_locks))
+		return 0;
+#endif
 	if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
 		debug_locks_off();
 		printk("BUG: MAX_LOCK_DEPTH too low!\n");
 		printk("turning off the locking correctness validator.\n");
 		return 0;
 	}
+
 	if (unlikely(curr->lockdep_depth > max_lockdep_depth))
 		max_lockdep_depth = curr->lockdep_depth;
 
@@ -2433,6 +2492,7 @@ EXPORT_SYMBOL_GPL(lock_release);
 void lockdep_reset(void)
 {
 	unsigned long flags;
+	int i;
 
 	raw_local_irq_save(flags);
 	current->curr_chain_key = 0;
@@ -2443,6 +2503,8 @@ void lockdep_reset(void)
 	nr_softirq_chains = 0;
 	nr_process_chains = 0;
 	debug_locks = 1;
+	for (i = 0; i < CHAINHASH_SIZE; i++)
+		INIT_LIST_HEAD(chainhash_table + i);
 	raw_local_irq_restore(flags);
 }
 
@@ -2479,7 +2541,7 @@ void lockdep_free_key_range(void *start, unsigned long size)
 	int i;
 
 	raw_local_irq_save(flags);
-	__raw_spin_lock(&hash_lock);
+	graph_lock();
 
 	/*
 	 * Unhash all classes that were created by this module:
@@ -2493,7 +2555,7 @@ void lockdep_free_key_range(void *start, unsigned long size)
 				zap_class(class);
 	}
 
-	__raw_spin_unlock(&hash_lock);
+	graph_unlock();
 	raw_local_irq_restore(flags);
 }
 
@@ -2521,26 +2583,26 @@ void lockdep_reset_lock(struct lockdep_map *lock)
 	 * Debug check: in the end all mapped classes should
 	 * be gone.
 	 */
-	__raw_spin_lock(&hash_lock);
+	graph_lock();
 	for (i = 0; i < CLASSHASH_SIZE; i++) {
 		head = classhash_table + i;
 		if (list_empty(head))
 			continue;
 		list_for_each_entry_safe(class, next, head, hash_entry) {
 			if (unlikely(class == lock->class_cache)) {
-				__raw_spin_unlock(&hash_lock);
-				DEBUG_LOCKS_WARN_ON(1);
+				if (debug_locks_off_graph_unlock())
+					WARN_ON(1);
 				goto out_restore;
 			}
 		}
 	}
-	__raw_spin_unlock(&hash_lock);
+	graph_unlock();
 
 out_restore:
 	raw_local_irq_restore(flags);
 }
 
-void __init lockdep_init(void)
+void lockdep_init(void)
 {
 	int i;
 
@@ -2727,4 +2789,3 @@ void debug_show_held_locks(struct task_struct *task)
 }
 
 EXPORT_SYMBOL_GPL(debug_show_held_locks);
-