Merge branch 'locking/core'

4 files changed, 187 insertions, 112 deletions

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index a95e5d1f4a9c..98dd6231d43b 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -660,6 +660,7 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
 	struct lockdep_subclass_key *key;
 	struct hlist_head *hash_head;
 	struct lock_class *class;
+	bool is_static = false;
 
 	if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
 		debug_locks_off();
@@ -673,10 +674,23 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
 
 	/*
 	 * Static locks do not have their class-keys yet - for them the key
-	 * is the lock object itself:
+	 * is the lock object itself. If the lock is in the per cpu area,
+	 * the canonical address of the lock (per cpu offset removed) is
+	 * used.
 	 */
-	if (unlikely(!lock->key))
-		lock->key = (void *)lock;
+	if (unlikely(!lock->key)) {
+		unsigned long can_addr, addr = (unsigned long)lock;
+
+		if (__is_kernel_percpu_address(addr, &can_addr))
+			lock->key = (void *)can_addr;
+		else if (__is_module_percpu_address(addr, &can_addr))
+			lock->key = (void *)can_addr;
+		else if (static_obj(lock))
+			lock->key = (void *)lock;
+		else
+			return ERR_PTR(-EINVAL);
+		is_static = true;
+	}
 
 	/*
 	 * NOTE: the class-key must be unique. For dynamic locks, a static
@@ -708,7 +722,7 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
 		}
 	}
 
-	return NULL;
+	return is_static || static_obj(lock->key) ? NULL : ERR_PTR(-EINVAL);
 }
 
 /*
@@ -726,19 +740,18 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 	DEBUG_LOCKS_WARN_ON(!irqs_disabled());
 
 	class = look_up_lock_class(lock, subclass);
-	if (likely(class))
+	if (likely(!IS_ERR_OR_NULL(class)))
 		goto out_set_class_cache;
 
 	/*
 	 * Debug-check: all keys must be persistent!
- 	 */
-	if (!static_obj(lock->key)) {
+	 */
+	if (IS_ERR(class)) {
 		debug_locks_off();
 		printk("INFO: trying to register non-static key.\n");
 		printk("the code is fine but needs lockdep annotation.\n");
 		printk("turning off the locking correctness validator.\n");
 		dump_stack();
-
 		return NULL;
 	}
 
@@ -3419,7 +3432,7 @@ static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
 		 * Clearly if the lock hasn't been acquired _ever_, we're not
 		 * holding it either, so report failure.
 		 */
-		if (!class)
+		if (IS_ERR_OR_NULL(class))
 			return 0;
 
 		/*
@@ -3437,13 +3450,67 @@ static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
 	return 0;
 }
 
+/* @depth must not be zero */
+static struct held_lock *find_held_lock(struct task_struct *curr,
+					struct lockdep_map *lock,
+					unsigned int depth, int *idx)
+{
+	struct held_lock *ret, *hlock, *prev_hlock;
+	int i;
+
+	i = depth - 1;
+	hlock = curr->held_locks + i;
+	ret = hlock;
+	if (match_held_lock(hlock, lock))
+		goto out;
+
+	ret = NULL;
+	for (i--, prev_hlock = hlock--;
+	     i >= 0;
+	     i--, prev_hlock = hlock--) {
+		/*
+		 * We must not cross into another context:
+		 */
+		if (prev_hlock->irq_context != hlock->irq_context) {
+			ret = NULL;
+			break;
+		}
+		if (match_held_lock(hlock, lock)) {
+			ret = hlock;
+			break;
+		}
+	}
+
+out:
+	*idx = i;
+	return ret;
+}
+
+static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
+			      int idx)
+{
+	struct held_lock *hlock;
+
+	for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
+		if (!__lock_acquire(hlock->instance,
+				    hlock_class(hlock)->subclass,
+				    hlock->trylock,
+				    hlock->read, hlock->check,
+				    hlock->hardirqs_off,
+				    hlock->nest_lock, hlock->acquire_ip,
+				    hlock->references, hlock->pin_count))
+			return 1;
+	}
+	return 0;
+}
+
 static int
 __lock_set_class(struct lockdep_map *lock, const char *name,
 		 struct lock_class_key *key, unsigned int subclass,
 		 unsigned long ip)
 {
 	struct task_struct *curr = current;
-	struct held_lock *hlock, *prev_hlock;
+	struct held_lock *hlock;
 	struct lock_class *class;
 	unsigned int depth;
 	int i;
@@ -3456,21 +3523,10 @@ __lock_set_class(struct lockdep_map *lock, const char *name,
 	if (DEBUG_LOCKS_WARN_ON(!depth))
 		return 0;
 
-	prev_hlock = NULL;
-	for (i = depth-1; i >= 0; i--) {
-		hlock = curr->held_locks + i;
-		/*
-		 * We must not cross into another context:
-		 */
-		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
-			break;
-		if (match_held_lock(hlock, lock))
-			goto found_it;
-		prev_hlock = hlock;
-	}
-	return print_unlock_imbalance_bug(curr, lock, ip);
+	hlock = find_held_lock(curr, lock, depth, &i);
+	if (!hlock)
+		return print_unlock_imbalance_bug(curr, lock, ip);
 
-found_it:
 	lockdep_init_map(lock, name, key, 0);
 	class = register_lock_class(lock, subclass, 0);
 	hlock->class_idx = class - lock_classes + 1;
@@ -3478,15 +3534,46 @@ found_it:
 	curr->lockdep_depth = i;
 	curr->curr_chain_key = hlock->prev_chain_key;
 
-	for (; i < depth; i++) {
-		hlock = curr->held_locks + i;
-		if (!__lock_acquire(hlock->instance,
-			hlock_class(hlock)->subclass, hlock->trylock,
-				hlock->read, hlock->check, hlock->hardirqs_off,
-				hlock->nest_lock, hlock->acquire_ip,
-				hlock->references, hlock->pin_count))
-			return 0;
-	}
+	if (reacquire_held_locks(curr, depth, i))
+		return 0;
+
+	/*
+	 * I took it apart and put it back together again, except now I have
+	 * these 'spare' parts.. where shall I put them.
+	 */
+	if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
+		return 0;
+	return 1;
+}
+
+static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
+{
+	struct task_struct *curr = current;
+	struct held_lock *hlock;
+	unsigned int depth;
+	int i;
+
+	depth = curr->lockdep_depth;
+	/*
+	 * This function is about (re)setting the class of a held lock,
+	 * yet we're not actually holding any locks. Naughty user!
+	 */
+	if (DEBUG_LOCKS_WARN_ON(!depth))
+		return 0;
+
+	hlock = find_held_lock(curr, lock, depth, &i);
+	if (!hlock)
+		return print_unlock_imbalance_bug(curr, lock, ip);
+
+	curr->lockdep_depth = i;
+	curr->curr_chain_key = hlock->prev_chain_key;
+
+	WARN(hlock->read, "downgrading a read lock");
+	hlock->read = 1;
+	hlock->acquire_ip = ip;
+
+	if (reacquire_held_locks(curr, depth, i))
+		return 0;
 
 	/*
 	 * I took it apart and put it back together again, except now I have
@@ -3508,7 +3595,7 @@ static int
 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
 {
 	struct task_struct *curr = current;
-	struct held_lock *hlock, *prev_hlock;
+	struct held_lock *hlock;
 	unsigned int depth;
 	int i;
 
@@ -3527,21 +3614,10 @@ __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
 	 * Check whether the lock exists in the current stack
 	 * of held locks:
 	 */
-	prev_hlock = NULL;
-	for (i = depth-1; i >= 0; i--) {
-		hlock = curr->held_locks + i;
-		/*
-		 * We must not cross into another context:
-		 */
-		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
-			break;
-		if (match_held_lock(hlock, lock))
-			goto found_it;
-		prev_hlock = hlock;
-	}
-	return print_unlock_imbalance_bug(curr, lock, ip);
+	hlock = find_held_lock(curr, lock, depth, &i);
+	if (!hlock)
+		return print_unlock_imbalance_bug(curr, lock, ip);
 
-found_it:
 	if (hlock->instance == lock)
 		lock_release_holdtime(hlock);
 
@@ -3568,15 +3644,8 @@ found_it:
 	curr->lockdep_depth = i;
 	curr->curr_chain_key = hlock->prev_chain_key;
 
-	for (i++; i < depth; i++) {
-		hlock = curr->held_locks + i;
-		if (!__lock_acquire(hlock->instance,
-			hlock_class(hlock)->subclass, hlock->trylock,
-				hlock->read, hlock->check, hlock->hardirqs_off,
-				hlock->nest_lock, hlock->acquire_ip,
-				hlock->references, hlock->pin_count))
-			return 0;
-	}
+	if (reacquire_held_locks(curr, depth, i + 1))
+		return 0;
 
 	/*
 	 * We had N bottles of beer on the wall, we drank one, but now
@@ -3741,6 +3810,23 @@ void lock_set_class(struct lockdep_map *lock, const char *name,
 }
 EXPORT_SYMBOL_GPL(lock_set_class);
 
+void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
+{
+	unsigned long flags;
+
+	if (unlikely(current->lockdep_recursion))
+		return;
+
+	raw_local_irq_save(flags);
+	current->lockdep_recursion = 1;
+	check_flags(flags);
+	if (__lock_downgrade(lock, ip))
+		check_chain_key(current);
+	current->lockdep_recursion = 0;
+	raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lock_downgrade);
+
 /*
  * We are not always called with irqs disabled - do that here,
  * and also avoid lockdep recursion:
@@ -3903,7 +3989,7 @@ static void
 __lock_contended(struct lockdep_map *lock, unsigned long ip)
 {
 	struct task_struct *curr = current;
-	struct held_lock *hlock, *prev_hlock;
+	struct held_lock *hlock;
 	struct lock_class_stats *stats;
 	unsigned int depth;
 	int i, contention_point, contending_point;
@@ -3916,22 +4002,12 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip)
 	if (DEBUG_LOCKS_WARN_ON(!depth))
 		return;
 
-	prev_hlock = NULL;
-	for (i = depth-1; i >= 0; i--) {
-		hlock = curr->held_locks + i;
-		/*
-		 * We must not cross into another context:
-		 */
-		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
-			break;
-		if (match_held_lock(hlock, lock))
-			goto found_it;
-		prev_hlock = hlock;
+	hlock = find_held_lock(curr, lock, depth, &i);
+	if (!hlock) {
+		print_lock_contention_bug(curr, lock, ip);
+		return;
 	}
-	print_lock_contention_bug(curr, lock, ip);
-	return;
 
-found_it:
 	if (hlock->instance != lock)
 		return;
 
@@ -3955,7 +4031,7 @@ static void
 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
 {
 	struct task_struct *curr = current;
-	struct held_lock *hlock, *prev_hlock;
+	struct held_lock *hlock;
 	struct lock_class_stats *stats;
 	unsigned int depth;
 	u64 now, waittime = 0;
@@ -3969,22 +4045,12 @@ __lock_acquired(struct lockdep_map *lock, unsigned long ip)
 	if (DEBUG_LOCKS_WARN_ON(!depth))
 		return;
 
-	prev_hlock = NULL;
-	for (i = depth-1; i >= 0; i--) {
-		hlock = curr->held_locks + i;
-		/*
-		 * We must not cross into another context:
-		 */
-		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
-			break;
-		if (match_held_lock(hlock, lock))
-			goto found_it;
-		prev_hlock = hlock;
+	hlock = find_held_lock(curr, lock, depth, &i);
+	if (!hlock) {
+		print_lock_contention_bug(curr, lock, _RET_IP_);
+		return;
 	}
-	print_lock_contention_bug(curr, lock, _RET_IP_);
-	return;
 
-found_it:
 	if (hlock->instance != lock)
 		return;
 
@@ -4172,7 +4238,7 @@ void lockdep_reset_lock(struct lockdep_map *lock)
 		 * If the class exists we look it up and zap it:
 		 */
 		class = look_up_lock_class(lock, j);
-		if (class)
+		if (!IS_ERR_OR_NULL(class))
 			zap_class(class);
 	}
 	/*
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index 90a74ccd85a4..4d48b1c4870d 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -124,10 +124,8 @@ EXPORT_SYMBOL(up_write);
  */
 void downgrade_write(struct rw_semaphore *sem)
 {
-	/*
-	 * lockdep: a downgraded write will live on as a write
-	 * dependency.
-	 */
+	lock_downgrade(&sem->dep_map, _RET_IP_);
+
 	rwsem_set_reader_owned(sem);
 	__downgrade_write(sem);
 }
diff --git a/kernel/locking/test-ww_mutex.c b/kernel/locking/test-ww_mutex.c
index 6b7abb334ca6..90d8d8879969 100644
--- a/kernel/locking/test-ww_mutex.c
+++ b/kernel/locking/test-ww_mutex.c
@@ -398,12 +398,11 @@ static void stress_inorder_work(struct work_struct *work)
 	if (!order)
 		return;
 
-	ww_acquire_init(&ctx, &ww_class);
-
 	do {
 		int contended = -1;
 		int n, err;
 
+		ww_acquire_init(&ctx, &ww_class);
 retry:
 		err = 0;
 		for (n = 0; n < nlocks; n++) {
@@ -433,9 +432,9 @@ retry:
 				    __func__, err);
 			break;
 		}
-	} while (--stress->nloops);
 
-	ww_acquire_fini(&ctx);
+		ww_acquire_fini(&ctx);
+	} while (--stress->nloops);
 
 	kfree(order);
 	kfree(stress);
@@ -470,9 +469,9 @@ static void stress_reorder_work(struct work_struct *work)
 	kfree(order);
 	order = NULL;
 
-	ww_acquire_init(&ctx, &ww_class);
-
 	do {
+		ww_acquire_init(&ctx, &ww_class);
+
 		list_for_each_entry(ll, &locks, link) {
 			err = ww_mutex_lock(ll->lock, &ctx);
 			if (!err)
@@ -495,9 +494,9 @@ static void stress_reorder_work(struct work_struct *work)
 		dummy_load(stress);
 		list_for_each_entry(ll, &locks, link)
 			ww_mutex_unlock(ll->lock);
-	} while (--stress->nloops);
 
-	ww_acquire_fini(&ctx);
+		ww_acquire_fini(&ctx);
+	} while (--stress->nloops);
 
 out:
 	list_for_each_entry_safe(ll, ln, &locks, link)
diff --git a/kernel/module.c b/kernel/module.c
index 7eba6dea4f41..5ef618133849 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -665,16 +665,7 @@ static void percpu_modcopy(struct module *mod,
 		memcpy(per_cpu_ptr(mod->percpu, cpu), from, size);
 }
 
-/**
- * is_module_percpu_address - test whether address is from module static percpu
- * @addr: address to test
- *
- * Test whether @addr belongs to module static percpu area.
- *
- * RETURNS:
- * %true if @addr is from module static percpu area
- */
-bool is_module_percpu_address(unsigned long addr)
+bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
 {
 	struct module *mod;
 	unsigned int cpu;
@@ -688,9 +679,11 @@ bool is_module_percpu_address(unsigned long addr)
 			continue;
 		for_each_possible_cpu(cpu) {
 			void *start = per_cpu_ptr(mod->percpu, cpu);
+			void *va = (void *)addr;
 
-			if ((void *)addr >= start &&
-			    (void *)addr < start + mod->percpu_size) {
+			if (va >= start && va < start + mod->percpu_size) {
+				if (can_addr)
+					*can_addr = (unsigned long) (va - start);
 				preempt_enable();
 				return true;
 			}
@@ -701,6 +694,20 @@ bool is_module_percpu_address(unsigned long addr)
 	return false;
 }
 
+/**
+ * is_module_percpu_address - test whether address is from module static percpu
+ * @addr: address to test
+ *
+ * Test whether @addr belongs to module static percpu area.
+ *
+ * RETURNS:
+ * %true if @addr is from module static percpu area
+ */
+bool is_module_percpu_address(unsigned long addr)
+{
+	return __is_module_percpu_address(addr, NULL);
+}
+
 #else /* ... !CONFIG_SMP */
 
 static inline void __percpu *mod_percpu(struct module *mod)
@@ -732,6 +739,11 @@ bool is_module_percpu_address(unsigned long addr)
 	return false;
 }
 
+bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
+{
+	return false;
+}
+
 #endif /* CONFIG_SMP */
 
 #define MODINFO_ATTR(field)	\