Lockdep: add lockdep_set_class_and_subclass() and lockdep_set_subclass()
This annotation makes it possible to assign a subclass on lock init. This
annotation is meant to reduce the _nested() annotations by assigning a
default subclass.
One could do without this annotation and rely on lockdep_set_class()
exclusively, but that would require a manual stack of struct lock_class_key
objects.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 4c05534..ba7156a 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -1177,7 +1177,7 @@
* itself, so actual lookup of the hash should be once per lock object.
*/
static inline struct lock_class *
-register_lock_class(struct lockdep_map *lock, unsigned int subclass)
+register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
{
struct lockdep_subclass_key *key;
struct list_head *hash_head;
@@ -1249,7 +1249,7 @@
out_unlock_set:
__raw_spin_unlock(&hash_lock);
- if (!subclass)
+ if (!subclass || force)
lock->class_cache = class;
DEBUG_LOCKS_WARN_ON(class->subclass != subclass);
@@ -1937,7 +1937,7 @@
* Initialize a lock instance's lock-class mapping info:
*/
void lockdep_init_map(struct lockdep_map *lock, const char *name,
- struct lock_class_key *key)
+ struct lock_class_key *key, int subclass)
{
if (unlikely(!debug_locks))
return;
@@ -1957,6 +1957,8 @@
lock->name = name;
lock->key = key;
lock->class_cache = NULL;
+ if (subclass)
+ register_lock_class(lock, subclass, 1);
}
EXPORT_SYMBOL_GPL(lockdep_init_map);
@@ -1995,7 +1997,7 @@
* Not cached yet or subclass?
*/
if (unlikely(!class)) {
- class = register_lock_class(lock, subclass);
+ class = register_lock_class(lock, subclass, 0);
if (!class)
return 0;
}