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Subject[PATCH v3 10/24] locking/lockdep: Introduce lock_class_cache_is_registered()
Date
This patch does not change any functionality but makes the
lockdep_reset_lock() function easier to read.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
kernel/locking/lockdep.c | 50 ++++++++++++++++++++++++----------------
1 file changed, 30 insertions(+), 20 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index b5c8fcb6c070..81388d028ac7 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4201,13 +4201,33 @@ 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);

@@ -4227,24 +4247,14 @@ void lockdep_reset_lock(struct lockdep_map *lock)
* 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();
--
2.20.0.rc2.403.gdbc3b29805-goog
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