[PATCH 2/4] locking/lockdep: Use hashtable.h for classhash_table

[Sasha Levin <sashal@kernel.org>]

Convert classhash_table in lockdep.c to use the generic hashtable
implementation from hashtable.h instead of the manual hlist_head array
implementation.

This simplifies the code and makes it more maintainable by using the
standard hashtable API and removes the need for custom hash lookup
functions.

Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/locking/lockdep.c | 69 ++++++++++++++--------------------------
 1 file changed, 24 insertions(+), 45 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 160cf8310eda0..b071bbf0d955c 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -404,12 +404,8 @@ static struct delayed_free {
 /*
  * The lockdep classes are in a hash-table as well, for fast lookup:
  */
-#define CLASSHASH_BITS		(MAX_LOCKDEP_KEYS_BITS - 1)
-#define CLASSHASH_SIZE		(1UL << CLASSHASH_BITS)
-#define __classhashfn(key)	hash_long((unsigned long)key, CLASSHASH_BITS)
-#define classhashentry(key)	(classhash_table + __classhashfn((key)))
-
-static struct hlist_head classhash_table[CLASSHASH_SIZE];
+#define CLASSHASH_BITS		(MAX_LOCKDEP_KEYS_BITS-1)
+static DEFINE_HASHTABLE(classhash_table, CLASSHASH_BITS);
 
 /*
  * We put the lock dependency chains into a hash-table as well, to cache
@@ -886,8 +882,8 @@ static noinstr struct lock_class *
 look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
 {
 	struct lockdep_subclass_key *key;
-	struct hlist_head *hash_head;
 	struct lock_class *class;
+	unsigned long hash;
 
 	if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
 		instrumentation_begin();
@@ -920,8 +916,7 @@ look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
 			sizeof(struct lockdep_map));
 
 	key = lock->key->subkeys + subclass;
-
-	hash_head = classhashentry(key);
+	hash = (unsigned long)key;
 
 	/*
 	 * We do an RCU walk of the hash, see lockdep_free_key_range().
@@ -929,7 +924,7 @@ look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
 	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
 		return NULL;
 
-	hlist_for_each_entry_rcu_notrace(class, hash_head, hash_entry) {
+	hash_for_each_possible_rcu_notrace(classhash_table, class, hash_entry, hash) {
 		if (class->key == key) {
 			/*
 			 * Huh! same key, different name? Did someone trample
@@ -1084,7 +1079,6 @@ static bool __check_data_structures(void)
 {
 	struct lock_class *class;
 	struct lock_chain *chain;
-	struct hlist_head *head;
 	struct lock_list *e;
 	int i;
 
@@ -1110,12 +1104,9 @@ static bool __check_data_structures(void)
 	}
 
 	/* Check the chain_key of all lock chains. */
-	for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
-		head = chainhash_table + i;
-		hlist_for_each_entry_rcu(chain, head, entry) {
-			if (!check_lock_chain_key(chain))
-				return false;
-		}
+	hash_for_each_rcu(chainhash_table, i, chain, entry) {
+		if (!check_lock_chain_key(chain))
+			return false;
 	}
 
 	/*
@@ -1279,8 +1270,8 @@ static struct lock_class *
 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 {
 	struct lockdep_subclass_key *key;
-	struct hlist_head *hash_head;
 	struct lock_class *class;
+	unsigned long hash;
 	int idx;
 
 	DEBUG_LOCKS_WARN_ON(!irqs_disabled());
@@ -1297,7 +1288,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 	}
 
 	key = lock->key->subkeys + subclass;
-	hash_head = classhashentry(key);
+	hash = (unsigned long)key;
 
 	if (!graph_lock()) {
 		return NULL;
@@ -1306,7 +1297,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 	 * We have to do the hash-walk again, to avoid races
 	 * with another CPU:
 	 */
-	hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
+	hash_for_each_possible_rcu(classhash_table, class, hash_entry, hash) {
 		if (class->key == key)
 			goto out_unlock_set;
 	}
@@ -1343,7 +1334,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 	 * We use RCU's safe list-add method to make
 	 * parallel walking of the hash-list safe:
 	 */
-	hlist_add_head_rcu(&class->hash_entry, hash_head);
+	hash_add_rcu(classhash_table, &class->hash_entry, hash);
 	/*
 	 * Remove the class from the free list and add it to the global list
 	 * of classes.
@@ -6206,14 +6197,10 @@ static void remove_class_from_lock_chains(struct pending_free *pf,
 					  struct lock_class *class)
 {
 	struct lock_chain *chain;
-	struct hlist_head *head;
 	int i;
 
-	for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
-		head = chainhash_table + i;
-		hlist_for_each_entry_rcu(chain, head, entry) {
-			remove_class_from_lock_chain(pf, chain, class);
-		}
+	hash_for_each_rcu(chainhash_table, i, chain, entry) {
+		remove_class_from_lock_chain(pf, chain, class);
 	}
 }
 
@@ -6370,18 +6357,14 @@ static void __lockdep_free_key_range(struct pending_free *pf, void *start,
 				     unsigned long size)
 {
 	struct lock_class *class;
-	struct hlist_head *head;
 	int i;
 
 	/* Unhash all classes that were created by a module. */
-	for (i = 0; i < CLASSHASH_SIZE; i++) {
-		head = classhash_table + i;
-		hlist_for_each_entry_rcu(class, head, hash_entry) {
-			if (!within(class->key, start, size) &&
-			    !within(class->name, start, size))
-				continue;
-			zap_class(pf, class);
-		}
+	hash_for_each_rcu(classhash_table, i, class, hash_entry) {
+		if (!within(class->key, start, size) &&
+		    !within(class->name, start, size))
+			continue;
+		zap_class(pf, class);
 	}
 }
 
@@ -6454,16 +6437,12 @@ void lockdep_free_key_range(void *start, unsigned long size)
 static bool lock_class_cache_is_registered(struct lockdep_map *lock)
 {
 	struct lock_class *class;
-	struct hlist_head *head;
 	int i, j;
 
-	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;
-		}
+	hash_for_each_rcu(classhash_table, i, class, hash_entry) {
+		for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
+			if (lock->class_cache[j] == class)
+				return true;
 	}
 	return false;
 }
@@ -6605,7 +6584,7 @@ void __init lockdep_init(void)
 	pr_info("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
 	pr_info("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
 	pr_info("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
-	pr_info("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
+	pr_info("... CLASSHASH_SIZE:          %lu\n", HASH_SIZE(classhash_table));
 	pr_info("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
 	pr_info("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
 	pr_info("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
-- 
2.39.5