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/include/linux/lockdep.h b/include/linux/lockdep.h
index 1314ca0..14fec2a 100644 (file)
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -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 +211,14 @@ extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
  * 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)
+#define lockdep_set_subclass(lock, sub)        \
+               lockdep_init_map(&(lock)->dep_map, #lock, \
+                                (lock)->dep_map.key, sub)
 
 /*
  * Acquire a lock.
@@ -257,10 +262,12 @@ 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)

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 4c05534..ba7156a 100644 (file)
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -1177,7 +1177,7 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
  * 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 *lock, unsigned int subclass)
 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, const char *name,
        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_map *lock, unsigned int subclass,
         * 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;
        }

diff --git a/kernel/mutex-debug.c b/kernel/mutex-debug.c
index e3203c6..1865164 100644 (file)
--- a/kernel/mutex-debug.c
+++ b/kernel/mutex-debug.c
@@ -91,7 +91,7 @@ void debug_mutex_init(struct mutex *lock, const char *name,
         * 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;

diff --git a/lib/rwsem-spinlock.c b/lib/rwsem-spinlock.c
index db4fed7..c4cfd6c 100644 (file)
--- a/lib/rwsem-spinlock.c
+++ b/lib/rwsem-spinlock.c
@@ -28,7 +28,7 @@ void __init_rwsem(struct rw_semaphore *sem, const char *name,
         * 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);

diff --git a/lib/rwsem.c b/lib/rwsem.c
index 901d0e7..cdb4e3d 100644 (file)
--- a/lib/rwsem.c
+++ b/lib/rwsem.c
@@ -19,7 +19,7 @@ void __init_rwsem(struct rw_semaphore *sem, const char *name,
         * 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);

diff --git a/lib/spinlock_debug.c b/lib/spinlock_debug.c
index dafaf1d..b6c4f89 100644 (file)
--- a/lib/spinlock_debug.c
+++ b/lib/spinlock_debug.c
@@ -20,7 +20,7 @@ void __spin_lock_init(spinlock_t *lock, const char *name,
         * 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 char *name,
         * 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;

diff --git a/net/core/sock.c b/net/core/sock.c
index b77e155..d472db4 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -823,7 +823,7 @@ static void inline sock_lock_init(struct sock *sk)
                                   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);
 }
 
 /**