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

include/linux/lockdep.h

···
 	 * Generation counter, when doing certain classes of graph walking,
 	 * to ensure that we check one node only once:
 	 */
-	unsigned int			version;
-
 	int				name_version;
 	const char			*name;
 

kernel/locking/lockdep.c

···
  * 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)
···
 
 /*
  * 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)
 {
···
 	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))
···
 	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);
···
 	/*
 	 * 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();
···
 /*
  * 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;
···
 		current->lockdep_recursion = 0;
 		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);
 
···
 	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;
···
 	 * 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);
···
 	 */
 }
 
-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:
···
 	 * 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();

kernel/sched/fair.c

···
 		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;

tools/lib/lockdep/include/liblockdep/common.h

···
 			struct lockdep_map *nest_lock, unsigned long ip);
 void lock_release(struct lockdep_map *lock, int nested,
 			unsigned long ip);
+void lockdep_reset_lock(struct lockdep_map *lock);
 extern void debug_check_no_locks_freed(const void *from, unsigned long len);
 
 #define STATIC_LOCKDEP_MAP_INIT(_name, _key) \

tools/lib/lockdep/include/liblockdep/mutex.h

···
 
 static inline int liblockdep_pthread_mutex_destroy(liblockdep_pthread_mutex_t *lock)
 {
+	lockdep_reset_lock(&lock->dep_map);
 	return pthread_mutex_destroy(&lock->mutex);
 }
 

tools/lib/lockdep/include/liblockdep/rwlock.h

···
 	return pthread_rwlock_tryrdlock(&lock->rwlock) == 0 ? 1 : 0;
 }
 
-static inline int liblockdep_pthread_rwlock_trywlock(liblockdep_pthread_rwlock_t *lock)
+static inline int liblockdep_pthread_rwlock_trywrlock(liblockdep_pthread_rwlock_t *lock)
 {
 	lock_acquire(&lock->dep_map, 0, 1, 0, 1, NULL, (unsigned long)_RET_IP_);
-	return pthread_rwlock_trywlock(&lock->rwlock) == 0 ? 1 : 0;
+	return pthread_rwlock_trywrlock(&lock->rwlock) == 0 ? 1 : 0;
 }
 
 static inline int liblockdep_rwlock_destroy(liblockdep_pthread_rwlock_t *lock)
···
 #define pthread_rwlock_unlock		liblockdep_pthread_rwlock_unlock
 #define pthread_rwlock_wrlock		liblockdep_pthread_rwlock_wrlock
 #define pthread_rwlock_tryrdlock	liblockdep_pthread_rwlock_tryrdlock
-#define pthread_rwlock_trywlock		liblockdep_pthread_rwlock_trywlock
+#define pthread_rwlock_trywrlock	liblockdep_pthread_rwlock_trywrlock
 #define pthread_rwlock_destroy		liblockdep_rwlock_destroy
 
 #endif

tools/lib/lockdep/lockdep.c

···
 	abort();
 }
 
+void print_irqtrace_events(struct task_struct *curr)
+{
+	abort();
+}
+
 static struct new_utsname *init_utsname(void)
 {
 	static struct new_utsname n = (struct new_utsname) {

tools/lib/lockdep/run_tests.sh

···
 #! /bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
-make &> /dev/null
+if ! make >/dev/null; then
+    echo "Building liblockdep failed."
+    echo "FAILED!"
+    exit 1
+fi
 
-for i in `ls tests/*.c`; do
+find tests -name '*.c' | sort | while read -r i; do
 	testname=$(basename "$i" .c)
-	gcc -o tests/$testname -pthread $i liblockdep.a -Iinclude -D__USE_LIBLOCKDEP &> /dev/null
 	echo -ne "$testname... "
-	if [ $(timeout 1 ./tests/$testname 2>&1 | wc -l) -gt 0 ]; then
+	if gcc -o "tests/$testname" -pthread "$i" liblockdep.a -Iinclude -D__USE_LIBLOCKDEP &&
+		timeout 1 "tests/$testname" 2>&1 | "tests/${testname}.sh"; then
 		echo "PASSED!"
 	else
 		echo "FAILED!"
 	fi
-	if [ -f "tests/$testname" ]; then
-		rm tests/$testname
-	fi
+	rm -f "tests/$testname"
 done
 
-for i in `ls tests/*.c`; do
+find tests -name '*.c' | sort | while read -r i; do
 	testname=$(basename "$i" .c)
-	gcc -o tests/$testname -pthread -Iinclude $i &> /dev/null
 	echo -ne "(PRELOAD) $testname... "
-	if [ $(timeout 1 ./lockdep ./tests/$testname 2>&1 | wc -l) -gt 0 ]; then
+	if gcc -o "tests/$testname" -pthread -Iinclude "$i" &&
+		timeout 1 ./lockdep "tests/$testname" 2>&1 |
+		"tests/${testname}.sh"; then
 		echo "PASSED!"
 	else
 		echo "FAILED!"
 	fi
-	if [ -f "tests/$testname" ]; then
-		rm tests/$testname
+	rm -f "tests/$testname"
+done
+
+find tests -name '*.c' | sort | while read -r i; do
+	testname=$(basename "$i" .c)
+	echo -ne "(PRELOAD + Valgrind) $testname... "
+	if gcc -o "tests/$testname" -pthread -Iinclude "$i" &&
+		{ timeout 10 valgrind --read-var-info=yes ./lockdep "./tests/$testname" >& "tests/${testname}.vg.out"; true; } &&
+		"tests/${testname}.sh" < "tests/${testname}.vg.out" &&
+		! grep -Eq '(^==[0-9]*== (Invalid |Uninitialised ))|Mismatched free|Source and destination overlap| UME ' "tests/${testname}.vg.out"; then
+		echo "PASSED!"
+	else
+		echo "FAILED!"
 	fi
+	rm -f "tests/$testname"
 done

tools/lib/lockdep/tests/AA.sh

···
+#!/bin/bash
+grep -q 'WARNING: possible recursive locking detected'

tools/lib/lockdep/tests/ABA.sh

···
+#!/bin/bash
+grep -q 'WARNING: possible recursive locking detected'

tools/lib/lockdep/tests/ABBA.c

···
 
 	LOCK_UNLOCK_2(a, b);
 	LOCK_UNLOCK_2(b, a);
+
+	pthread_mutex_destroy(&b);
+	pthread_mutex_destroy(&a);
 }

tools/lib/lockdep/tests/ABBA.sh

···
+#!/bin/bash
+grep -q 'WARNING: possible circular locking dependency detected'

tools/lib/lockdep/tests/ABBA_2threads.sh

···
+#!/bin/bash
+grep -q 'WARNING: possible circular locking dependency detected'

tools/lib/lockdep/tests/ABBCCA.c

···
 	LOCK_UNLOCK_2(a, b);
 	LOCK_UNLOCK_2(b, c);
 	LOCK_UNLOCK_2(c, a);
+
+	pthread_mutex_destroy(&c);
+	pthread_mutex_destroy(&b);
+	pthread_mutex_destroy(&a);
 }

tools/lib/lockdep/tests/ABBCCA.sh

···
+#!/bin/bash
+grep -q 'WARNING: possible circular locking dependency detected'

tools/lib/lockdep/tests/ABBCCDDA.c

···
 	LOCK_UNLOCK_2(b, c);
 	LOCK_UNLOCK_2(c, d);
 	LOCK_UNLOCK_2(d, a);
+
+	pthread_mutex_destroy(&d);
+	pthread_mutex_destroy(&c);
+	pthread_mutex_destroy(&b);
+	pthread_mutex_destroy(&a);
 }

tools/lib/lockdep/tests/ABBCCDDA.sh

···
+#!/bin/bash
+grep -q 'WARNING: possible circular locking dependency detected'

tools/lib/lockdep/tests/ABCABC.c

···
 	LOCK_UNLOCK_2(a, b);
 	LOCK_UNLOCK_2(c, a);
 	LOCK_UNLOCK_2(b, c);
+
+	pthread_mutex_destroy(&c);
+	pthread_mutex_destroy(&b);
+	pthread_mutex_destroy(&a);
 }

tools/lib/lockdep/tests/ABCABC.sh

···
+#!/bin/bash
+grep -q 'WARNING: possible circular locking dependency detected'

tools/lib/lockdep/tests/ABCDBCDA.c

···
 	LOCK_UNLOCK_2(c, d);
 	LOCK_UNLOCK_2(b, c);
 	LOCK_UNLOCK_2(d, a);
+
+	pthread_mutex_destroy(&d);
+	pthread_mutex_destroy(&c);
+	pthread_mutex_destroy(&b);
+	pthread_mutex_destroy(&a);
 }

tools/lib/lockdep/tests/ABCDBCDA.sh

···
+#!/bin/bash
+grep -q 'WARNING: possible circular locking dependency detected'

tools/lib/lockdep/tests/ABCDBDDA.c

···
 	LOCK_UNLOCK_2(c, d);
 	LOCK_UNLOCK_2(b, d);
 	LOCK_UNLOCK_2(d, a);
+
+	pthread_mutex_destroy(&d);
+	pthread_mutex_destroy(&c);
+	pthread_mutex_destroy(&b);
+	pthread_mutex_destroy(&a);
 }

tools/lib/lockdep/tests/ABCDBDDA.sh

···
+#!/bin/bash
+grep -q 'WARNING: possible circular locking dependency detected'

tools/lib/lockdep/tests/WW.sh

···
+#!/bin/bash
+grep -q 'WARNING: possible recursive locking detected'

tools/lib/lockdep/tests/unlock_balance.c

···
 	pthread_mutex_lock(&a);
 	pthread_mutex_unlock(&a);
 	pthread_mutex_unlock(&a);
+
+	pthread_mutex_destroy(&a);
 }

tools/lib/lockdep/tests/unlock_balance.sh

···
+#!/bin/bash
+grep -q 'WARNING: bad unlock balance detected'