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Subject[PATCH 1/2] lockdep: lockdep_set_class_and_subclass
Add lockdep_set_class_and_subclass() to the lockdep annotations.

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>
---
include/linux/lockdep.h | 12 ++++++++----
kernel/lockdep.c | 10 ++++++----
kernel/mutex-debug.c | 2 +-
lib/rwsem-spinlock.c | 2 +-
lib/rwsem.c | 2 +-
lib/spinlock_debug.c | 4 ++--
net/core/sock.c | 2 +-
7 files changed, 20 insertions(+), 14 deletions(-)
Index: linux-2.6-mm/include/linux/lockdep.h
===================================================================
--- linux-2.6-mm.orig/include/linux/lockdep.h 2006-09-26 11:05:29.000000000 +0200
+++ linux-2.6-mm/include/linux/lockdep.h 2006-09-26 13:10:40.000000000 +0200
@@ -202,7 +202,7 @@ extern int lockdep_internal(void);
*/

extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
- struct lock_class_key *key);
+ struct lock_class_key *key, int subclass);

/*
* Reinitialize a lock key - for cases where there is special locking or
@@ -211,9 +211,11 @@ extern void lockdep_init_map(struct lock
* or they are too narrow (they suffer from a false class-split):
*/
#define lockdep_set_class(lock, key) \
- lockdep_init_map(&(lock)->dep_map, #key, key)
+ lockdep_init_map(&(lock)->dep_map, #key, key, 0)
#define lockdep_set_class_and_name(lock, key, name) \
- lockdep_init_map(&(lock)->dep_map, name, key)
+ lockdep_init_map(&(lock)->dep_map, name, key, 0)
+#define lockdep_set_class_and_subclass(lock, key, sub) \
+ lockdep_init_map(&(lock)->dep_map, #key, key, sub)

/*
* Acquire a lock.
@@ -257,10 +259,12 @@ static inline int lockdep_internal(void)
# define lock_release(l, n, i) do { } while (0)
# define lockdep_init() do { } while (0)
# define lockdep_info() do { } while (0)
-# define lockdep_init_map(lock, name, key) do { (void)(key); } while (0)
+# define lockdep_init_map(lock, name, key, sub) do { (void)(key); } while (0)
# define lockdep_set_class(lock, key) do { (void)(key); } while (0)
# define lockdep_set_class_and_name(lock, key, name) \
do { (void)(key); } while (0)
+#define lockdep_set_class_and_subclass(lock, key, sub) \
+ do { (void)(key); } while (0)
# define INIT_LOCKDEP
# define lockdep_reset() do { debug_locks = 1; } while (0)
# define lockdep_free_key_range(start, size) do { } while (0)
Index: linux-2.6-mm/kernel/lockdep.c
===================================================================
--- linux-2.6-mm.orig/kernel/lockdep.c 2006-09-26 11:05:29.000000000 +0200
+++ linux-2.6-mm/kernel/lockdep.c 2006-09-26 13:13:09.000000000 +0200
@@ -1177,7 +1177,7 @@ look_up_lock_class(struct lockdep_map *l
* 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 @@ register_lock_class(struct lockdep_map *
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 @@ void trace_softirqs_off(unsigned long ip
* 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 @@ void lockdep_init_map(struct lockdep_map
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 @@ static int __lock_acquire(struct lockdep
* 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;
}
Index: linux-2.6-mm/kernel/mutex-debug.c
===================================================================
--- linux-2.6-mm.orig/kernel/mutex-debug.c 2006-09-26 11:05:29.000000000 +0200
+++ linux-2.6-mm/kernel/mutex-debug.c 2006-09-26 13:10:40.000000000 +0200
@@ -91,7 +91,7 @@ void debug_mutex_init(struct mutex *lock
* Make sure we are not reinitializing a held lock:
*/
debug_check_no_locks_freed((void *)lock, sizeof(*lock));
- lockdep_init_map(&lock->dep_map, name, key);
+ lockdep_init_map(&lock->dep_map, name, key, 0);
#endif
lock->owner = NULL;
lock->magic = lock;
Index: linux-2.6-mm/lib/rwsem-spinlock.c
===================================================================
--- linux-2.6-mm.orig/lib/rwsem-spinlock.c 2006-09-26 11:05:29.000000000 +0200
+++ linux-2.6-mm/lib/rwsem-spinlock.c 2006-09-26 13:10:40.000000000 +0200
@@ -28,7 +28,7 @@ void __init_rwsem(struct rw_semaphore *s
* Make sure we are not reinitializing a held semaphore:
*/
debug_check_no_locks_freed((void *)sem, sizeof(*sem));
- lockdep_init_map(&sem->dep_map, name, key);
+ lockdep_init_map(&sem->dep_map, name, key, 0);
#endif
sem->activity = 0;
spin_lock_init(&sem->wait_lock);
Index: linux-2.6-mm/lib/rwsem.c
===================================================================
--- linux-2.6-mm.orig/lib/rwsem.c 2006-09-26 11:05:29.000000000 +0200
+++ linux-2.6-mm/lib/rwsem.c 2006-09-26 13:10:40.000000000 +0200
@@ -19,7 +19,7 @@ void __init_rwsem(struct rw_semaphore *s
* Make sure we are not reinitializing a held semaphore:
*/
debug_check_no_locks_freed((void *)sem, sizeof(*sem));
- lockdep_init_map(&sem->dep_map, name, key);
+ lockdep_init_map(&sem->dep_map, name, key, 0);
#endif
sem->count = RWSEM_UNLOCKED_VALUE;
spin_lock_init(&sem->wait_lock);
Index: linux-2.6-mm/lib/spinlock_debug.c
===================================================================
--- linux-2.6-mm.orig/lib/spinlock_debug.c 2006-09-26 11:05:29.000000000 +0200
+++ linux-2.6-mm/lib/spinlock_debug.c 2006-09-26 13:10:40.000000000 +0200
@@ -20,7 +20,7 @@ void __spin_lock_init(spinlock_t *lock,
* Make sure we are not reinitializing a held lock:
*/
debug_check_no_locks_freed((void *)lock, sizeof(*lock));
- lockdep_init_map(&lock->dep_map, name, key);
+ lockdep_init_map(&lock->dep_map, name, key, 0);
#endif
lock->raw_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
lock->magic = SPINLOCK_MAGIC;
@@ -38,7 +38,7 @@ void __rwlock_init(rwlock_t *lock, const
* Make sure we are not reinitializing a held lock:
*/
debug_check_no_locks_freed((void *)lock, sizeof(*lock));
- lockdep_init_map(&lock->dep_map, name, key);
+ lockdep_init_map(&lock->dep_map, name, key, 0);
#endif
lock->raw_lock = (raw_rwlock_t) __RAW_RW_LOCK_UNLOCKED;
lock->magic = RWLOCK_MAGIC;
Index: linux-2.6-mm/net/core/sock.c
===================================================================
--- linux-2.6-mm.orig/net/core/sock.c 2006-09-26 11:05:29.000000000 +0200
+++ linux-2.6-mm/net/core/sock.c 2006-09-26 13:10:40.000000000 +0200
@@ -823,7 +823,7 @@ static void inline sock_lock_init(struct
af_family_slock_key_strings[sk->sk_family]);
lockdep_init_map(&sk->sk_lock.dep_map,
af_family_key_strings[sk->sk_family],
- af_family_keys + sk->sk_family);
+ af_family_keys + sk->sk_family, 0);
}

/**
--

-
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