Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "The main change in this cycle are initial preparatory bits of dynamic
  lockdep keys support from Bart Van Assche.

  There are also misc changes, a comment cleanup and a data structure
  cleanup"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Clean up comment in nohz_idle_balance()
  locking/lockdep: Stop using RCU primitives to access 'all_lock_classes'
  locking/lockdep: Make concurrent lockdep_reset_lock() calls safe
  locking/lockdep: Remove a superfluous INIT_LIST_HEAD() statement
  locking/lockdep: Introduce lock_class_cache_is_registered()
  locking/lockdep: Inline __lockdep_init_map()
  locking/lockdep: Declare local symbols static
  tools/lib/lockdep/tests: Test the lockdep_reset_lock() implementation
  tools/lib/lockdep: Add dummy print_irqtrace_events() implementation
  tools/lib/lockdep: Rename "trywlock" into "trywrlock"
  tools/lib/lockdep/tests: Run lockdep tests a second time under Valgrind
  tools/lib/lockdep/tests: Improve testing accuracy
  tools/lib/lockdep/tests: Fix shellcheck warnings
  tools/lib/lockdep/tests: Display compiler warning and error messages
  locking/lockdep: Remove ::version from lock_class structure

2 files changed, 44 insertions, 36 deletions

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index ef27f98714c0..95932333a48b 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -138,6 +138,9 @@ static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
  * get freed - this significantly simplifies the debugging code.
  */
 unsigned long nr_lock_classes;
+#ifndef CONFIG_DEBUG_LOCKDEP
+static
+#endif
 struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
 
 static inline struct lock_class *hlock_class(struct held_lock *hlock)
@@ -626,7 +629,8 @@ static int static_obj(void *obj)
 
 /*
  * To make lock name printouts unique, we calculate a unique
- * class->name_version generation counter:
+ * class->name_version generation counter. The caller must hold the graph
+ * lock.
  */
 static int count_matching_names(struct lock_class *new_class)
 {
@@ -636,7 +640,7 @@ static int count_matching_names(struct lock_class *new_class)
         if (!new_class->name)
                 return 0;
 
-        list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
+        list_for_each_entry(class, &all_lock_classes, lock_entry) {
                 if (new_class->key - new_class->subclass == class->key)
                         return class->name_version;
                 if (class->name && !strcmp(class->name, new_class->name))
@@ -789,7 +793,6 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
         class->key = key;
         class->name = lock->name;
         class->subclass = subclass;
-        INIT_LIST_HEAD(&class->lock_entry);
         INIT_LIST_HEAD(&class->locks_before);
         INIT_LIST_HEAD(&class->locks_after);
         class->name_version = count_matching_names(class);
@@ -801,7 +804,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
         /*
          * Add it to the global list of classes:
          */
-        list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
+        list_add_tail(&class->lock_entry, &all_lock_classes);
 
         if (verbose(class)) {
                 graph_unlock();
@@ -3088,7 +3091,7 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
 /*
  * Initialize a lock instance's lock-class mapping info:
  */
-static void __lockdep_init_map(struct lockdep_map *lock, const char *name,
+void lockdep_init_map(struct lockdep_map *lock, const char *name,
                       struct lock_class_key *key, int subclass)
 {
         int i;
@@ -3144,12 +3147,6 @@ static void __lockdep_init_map(struct lockdep_map *lock, const char *name,
                 raw_local_irq_restore(flags);
         }
 }
-
-void lockdep_init_map(struct lockdep_map *lock, const char *name,
-                      struct lock_class_key *key, int subclass)
-{
-        __lockdep_init_map(lock, name, key, subclass);
-}
 EXPORT_SYMBOL_GPL(lockdep_init_map);
 
 struct lock_class_key __lockdep_no_validate__;
@@ -4126,6 +4123,9 @@ void lockdep_reset(void)
         raw_local_irq_restore(flags);
 }
 
+/*
+ * Remove all references to a lock class. The caller must hold the graph lock.
+ */
 static void zap_class(struct lock_class *class)
 {
         int i;
@@ -4142,7 +4142,7 @@ static void zap_class(struct lock_class *class)
          * Unhash the class and remove it from the all_lock_classes list:
          */
         hlist_del_rcu(&class->hash_entry);
-        list_del_rcu(&class->lock_entry);
+        list_del(&class->lock_entry);
 
         RCU_INIT_POINTER(class->key, NULL);
         RCU_INIT_POINTER(class->name, NULL);
@@ -4204,15 +4204,36 @@ void lockdep_free_key_range(void *start, unsigned long size)
          */
 }
 
-void lockdep_reset_lock(struct lockdep_map *lock)
+/*
+ * Check whether any element of the @lock->class_cache[] array refers to a
+ * registered lock class. The caller must hold either the graph lock or the
+ * RCU read lock.
+ */
+static bool lock_class_cache_is_registered(struct lockdep_map *lock)
 {
         struct lock_class *class;
         struct hlist_head *head;
-        unsigned long flags;
         int i, j;
-        int locked;
+
+        for (i = 0; i < CLASSHASH_SIZE; i++) {
+                head = classhash_table + i;
+                hlist_for_each_entry_rcu(class, head, hash_entry) {
+                        for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
+                                if (lock->class_cache[j] == class)
+                                        return true;
+                }
+        }
+        return false;
+}
+
+void lockdep_reset_lock(struct lockdep_map *lock)
+{
+        struct lock_class *class;
+        unsigned long flags;
+        int j, locked;
 
         raw_local_irq_save(flags);
+        locked = graph_lock();
 
         /*
          * Remove all classes this lock might have:
@@ -4229,25 +4250,14 @@ void lockdep_reset_lock(struct lockdep_map *lock)
          * Debug check: in the end all mapped classes should
          * be gone.
          */
-        locked = graph_lock();
-        for (i = 0; i < CLASSHASH_SIZE; i++) {
-                head = classhash_table + i;
-                hlist_for_each_entry_rcu(class, head, hash_entry) {
-                        int match = 0;
-
-                        for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
-                                match |= class == lock->class_cache[j];
-
-                        if (unlikely(match)) {
-                                if (debug_locks_off_graph_unlock()) {
-                                        /*
-                                         * We all just reset everything, how did it match?
-                                         */
-                                        WARN_ON(1);
-                                }
-                                goto out_restore;
-                        }
+        if (unlikely(lock_class_cache_is_registered(lock))) {
+                if (debug_locks_off_graph_unlock()) {
+                        /*
+                         * We all just reset everything, how did it match?
+                         */
+                        WARN_ON(1);
                 }
+                goto out_restore;
         }
         if (locked)
                 graph_unlock();
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ac855b2f4774..db514993565b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9533,9 +9533,7 @@ static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
                 return false;
         }
 
-        /*
-         * barrier, pairs with nohz_balance_enter_idle(), ensures ...
-         */
+        /* could be _relaxed() */
         flags = atomic_fetch_andnot(NOHZ_KICK_MASK, nohz_flags(this_cpu));
         if (!(flags & NOHZ_KICK_MASK))
                 return false;